Parimad Eesti Flakes toolid

Index Scriptorium Estoniae

2007-01-01

ELKE Mööbli, Eesti Sisearhitektide Liidu ja Piiroinen OY korraldatud Flakes toolide Eesti kujunduskonkursi tulemused: I preemia - Heino Prunsvelt, II - Kadi Hektor, III - Andres Labi. Piironen OÜ eripreemiad - Andres Lember, Gerly Grünbaum, Kaarin Kokk

Coupling of the FLake model to the Surfex externalized surface model

Energy Technology Data Exchange (ETDEWEB)

Salgado, R. (Univ. of Evora, Centro de Geofisica de Evora (Portugal)); Le Moigne, P. (CNRM/GAME, Meteo-France/CNRS, Toulouse (France))

2010-07-01

The FLake model parameterizes the local-scale energy exchanges between lake surfaces and the atmosphere. FLake simulates the temperature profile as well as the budgets of heat and turbulent kinetic energy in water. Its implementation into the Surfex system, the externalized surface scheme devoted to research and operational forecasts, is presented here. The paper describes a validation of the coupled system Surfex-FLake based on measurements carried out on the Alqueva reservoir in southern Portugal. This paper shows how the use of FLake in the Surfex system improves surface temperature and turbulent fluxes at the water-atmosphere interface and explains the minor changes made in the computation of the shape function in order to adapt the FLake model to warm lakes, like the one used for this study. (orig.)

Flaking of co-deposited hydrogenated carbon layers on the TFTR limiter

International Nuclear Information System (INIS)

Skinner, C.H.; Gentile, C.A.; Menon, M.M.; Barry, R.E.

1999-01-01

Flaking of co-deposited layers on the inner limiter tiles was recently observed in TFTR. This phenomenon was unexpected and has occurred since the termination of plasma operations on 4 April 1997. Flaking affects approximately 15% of the observable tiles and appears on isotropic graphite but not on carbon fibre composite tiles. Photographic images of the flakes and precise measurements of the limiter geometry are reported. The mobilizability of tritium retained in co-deposited layers is an important factor in safety analyses of future DT reactors. A programme to analyse the flakes and tiles is underway. (author). Letter-to-the-editor

The cholesterol-lowering effect of coconut flakes in humans with moderately raised serum cholesterol.

Science.gov (United States)

Trinidad, Trinidad P; Loyola, Anacleta S; Mallillin, Aida C; Valdez, Divinagracia H; Askali, Faridah C; Castillo, Joan C; Resaba, Rosario L; Masa, Dina B

2004-01-01

This study investigated the effect of coconut flakes on serum cholesterol levels of humans with moderately raised serum cholesterol in 21 subjects. The serum total cholesterol of subjects differed and ranged from 259 to 283 mg/dL. The study was conducted in a double-blind randomized crossover design on a 14-week period, consisting of four 2-week experimental periods, with each experimental period separated by a 2-week washout period. The test foods were as follows: corn flakes as the control food, oat bran flakes as the reference food, and corn flakes with 15% and 25% dietary fiber from coconut flakes (made from coconut flour production). Results showed a significant percent reduction in serum total and low-density lipoprotein (LDL) cholesterol (in mg/dL) for all test foods, except for corn flakes, as follows: oat bran flakes, 8.4 +/- 1.4 and 8.8 +/- 6.0, respectively; 15% coconut flakes, 6.9 +/- 1.1 and 11.0 +/- 4.0, respectively; and 25% coconut flakes, 10.8 +/- 1.3 and 9.2 +/- 5.4, respectively. Serum triglycerides were significantly reduced for all test foods: corn flakes, 14.5 +/- 6.3%; oat bran flakes, 22.7 +/- 2.9%; 15% coconut flakes, 19.3 +/- 5.7%; and 25% coconut flakes, 21.8 +/- 6.0%. Only 60% of the subjects were considered for serum triglycerides reduction (serum triglycerides >170 mg/dL). In conclusion, both 15% and 25% coconut flakes reduced serum total and LDL cholesterol and serum triglycerides of humans with moderately raised serum cholesterol levels. Coconut flour is a good source of both soluble and insoluble dietary fiber, and both types of fiber may have significant role in the reduction of the above lipid biomarker. To our knowledge, this is the first study conducted to show a relationship between dietary fiber from a coconut by-product and a lipid biomarker. Results from this study serves as a good basis in the development of coconut flakes/flour as a functional food, justifying the increased production of coconut and coconut by-products.

9 CFR 590.546 - Albumen flake process drying facilities.

Science.gov (United States)

2010-01-01

... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Albumen flake process drying facilities. 590.546 Section 590.546 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE... INSPECTION ACT) Sanitary, Processing, and Facility Requirements § 590.546 Albumen flake process drying...

Flaking and blistering on He and Ne bombardments

International Nuclear Information System (INIS)

Kamada, K.; Naramoto, H.

1979-01-01

Large scale exfoliation formed by 300 keV He + bombardment of niobium without any preceding blistering is investigated, in comparison with the blistering due to 450 and 850 keV Ne + bombardments. In-situ observations of the erosion processes were performed in a scanning electron microscope connected to the Van de Graaff. Critical doses of 7.2 x 10 17 He + /cm 2 , 2.4 x 10 17 Ne + /cm 2 and 4.0 x 10 17 Ne + /cm 2 were obtained for the 300 keV He flaking, 450 keV Ne blistering and 850 keV Ne blistering, respectively. The He flaking was presumed to be due to brittle fashion peeling-off of the surface layer by the bending moment driven by the internal gas pressure. The blistering, on the other hand, was presumed to be the result of the ductile fashion spreading of the lenticular bubble in the sub-surface layer. The necessary pressure for the peeling-off of the cover was calculated, and was speculated to be able to work as the driving force for the flaking from its unexpectedly low values. Fractographies under the exfoliations were discussed for both flaking and blistering. (author)

Improving the nutritive characteristics of corn flakes enriched with functional components

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Košutić Milenko B.

2017-01-01

Full Text Available This paper investigates the effects of simultaneous addition of sunflower (3, 6 or 9 g/100 g of sample and dry residue of wild oregano (0.5 or 1 g/100 g of sample on the essential amino acids pattern and antioxidant potential of flake products. The accepted experimental design plan was 34. Data point that Score and PDCAAS values in flake products increase with increasing share of sunflower. Maximum value of phenolic compounds and antioxidant activity were experienced of TPC 2.84 mg/g, DPPH 0.75 mg/ml, FRAP 1.57 mg/g with the product having maximum shares of sunflower and dry residue of wild oregano. Tukey’s HSD test showed statistically significant differences between most of the mean values of amino acids content and antioxidant activity in the observed corn flakes. The response surface method has been applied for evaluation of amino acid content and antioxidative potential of corn flakes. Sunflower in flake products positively contributed to the protein nutritive value and dry residues of wild oregano elevated antioxidant potential of flake products and also contributed to the food waste valorisation in the food industry. Corn flakes are new products with improved essential amino acid pattern, antioxidant activity and functional properties due to added dry residue of wild oregano and sunflower. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 46005 and Grant no. TR 31027

FEM analysis of magnetic flake composites

Science.gov (United States)

Claassen, J. H.

2009-07-01

A composite comprised of layered flake-like magnetic particles embedded in an insulating medium has been proposed as a low permeability, low loss core material. This would be an alternative to "distributed air gap" compressed powder cores that are widely used for inductors in power applications. Since the lowest loss metallic materials are manufactured in the form of very thin sheets, the particles after pulverizing would be in the form of flakes. The effective permeability and average core loss have been computed for model systems of flake composites in a two-dimensional approximation. The core loss is modeled by eddy current dissipation in the low-frequency limit, where the conductor thickness is much less than the skin depth. It is found that useful values of permeability should be obtained for a modest filling fraction of magnetic material, in contrast to the powder cores which require a value close to unity. The core loss will scale as the inverse of filling fraction, with a small additional enhancement due to perpendicular field components. It is thus expected that useful core materials may be attainable without the necessity of large compaction forces.

High-quality graphene flakes exfoliated on a flat hydrophobic polymer

DEFF Research Database (Denmark)

Pedrinazzi, Paolo; Caridad, José M.; Mackenzie, David M. A.

2018-01-01

the environment of the graphene flake is completely changed, by encapsulating preselected flakes between hexagonal boron nitride layers. The exfoliation of clean, pristine graphene layers directly on flat polymer substrates enables high performance, supported, and non-encapsulated graphene devices for flexible...

Flaking behavior and microstructure evolution of nickel and copper powder during mechanical milling in liquid environment

International Nuclear Information System (INIS)

Xiao Xiao; Zeng Zigao; Zhao Zhongwei; Xiao Songwen

2008-01-01

To prepare metal flakes with a high flaking level and investigate the microstructure of metal flakes, nickel and copper powder were mechanically milled in liquid environment and the microstructure of powders was investigated by X-ray diffraction. The milling process can be divided into flaking and broken stages. At the flaking stage, milled metal powders exhibited high flaking level and flaky microshape, and became preferred orientation. While at the broken stage, the milled powders presented a low flaking level and irregular microshape, and was not preferred orientation any longer. The grain size, microstrain and dislocation density along direction varied with milling time differently from that along direction. The flaking level of the milled powders was related to the preferred orientation, and more closely to the deformation mechanism. We can strengthen the formation of preferred orientation to obtain metal powders with a high flaking level

Effect of overlap length on the mechanical properties of flake reinforced thermoplastic composites

NARCIS (Netherlands)

Abdul Rasheed, M. I.; van Hattum, F.W.J.; Rietman, B.; Visser, H. A.; Akkerman, R.

2015-01-01

The in-plane mechanical properties of laminates with two dimensional planar reinforcing elements (flakes in this case) are investigated. A woven structure for the flakes is considered in this study, comprising of fiber bundles in both warp and weft direction. Failure of the flake or the interface

Environmental and health effects review for obscurant graphite flakes. Final report, 1991 July--1993 May

Energy Technology Data Exchange (ETDEWEB)

Driver, C.J.; Ligotke, M.W.; Landis, W.G.; Downs, J.L.; Tiller, B.L.; Moore, E.B. Jr.; Cataldo, D.A.

1993-07-01

The health and environmental effects of obscurant graphite flakes were reviewed and compared to predicted levels of graphite flake material in the field during typical testing and training scenarios. Graphite flake dispersion and deposition for simulated mechanical and pyrotechnic releases were determined using a modified Gaussian atmospheric plume-dispersion model. The potential for wind resuspension of graphite flakes is controlled by weathering processes and incorporation rates in soil. Chemically, graphite flakes pose little risk to aquatic or terrestrial systems. Mechanical damage to plants and invertebrate and vertebrate organisms from the flakes is also minimal. In humans, the pathological and physiological response to inhaled graphite flake is similar to that induced by nuisance dusts and cause only transient pulmonary changes. Repeated exposure to very high concentrations (such as those near the source generator) may overwhelm the clearance mechanisms of the lung and result in pulmonary damage from the retained particles in unprotected individuals. However, these lesions either resolve with time or are of limited severity. Health effects of mixed aerosols of mixed aerosols of graphite and fog oil are similar to those produced by graphite flakes alone. Environmental impacts of fog oil-coated graphite flakes are not well known.

Research on metal-plated cellulose nitrate flakes and their infrared / millimeter wave characteristics

Science.gov (United States)

Ye, Shu-qin; Zhu, Chen-guang; Wang, Li-hong; Ou'yang, De-hua; Pan, Gong-pei

2016-10-01

Copper-plated and silver-plated cellulose nitrate flakes, which were prepared by using chemical plating technology, were used to jam infrared detector and millimeter-wave radar. It was tested for the conductivity and infrared jamming performance of plating and also the RCS (Radar Cross Section) performance of millimeter-wave radar. Test results showed that the prepared metal-plated cellulose nitrate flakes have obvious conductivity, and infrared total radiation energy of silver plating and copper plating had approximately increased 32% and 21% respectively. Through determination, the millimeter-wave reflecting property and RCS of silver-plated cellulose nitrate flakes were higher than that of copper-plated cellulose nitrate flakes. Therefore, silver-plated cellulose nitrate flakes can be used as an effective infrared / millimeter wave composite jamming material.

The performance of FLake in the Met Office Unified Model

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Gabriel Gerard Rooney

2013-12-01

Full Text Available We present results from the coupling of FLake to the Met Office Unified Model (MetUM. The coupling and initialisation are first described, and the results of testing the coupled model in local and global model configurations are presented. These show that FLake has a small statistical impact on screen temperature, but has the potential to modify the weather in the vicinity of areas of significant inland water. Examination of FLake lake ice has revealed that the behaviour of lakes in the coupled model is unrealistic in some areas of significant sub-grid orography. Tests of various modifications to ameliorate this behaviour are presented. The results indicate which of the possible model changes best improve the annual cycle of lake ice. As FLake has been developed and tuned entirely outside the Unified Model system, these results can be interpreted as a useful objective measure of the performance of the Unified Model in terms of its near-surface characteristics.

Exfoliation of non-oxidized graphene flakes for scalable conductive film.

Science.gov (United States)

Park, Kwang Hyun; Kim, Bo Hyun; Song, Sung Ho; Kwon, Jiyoung; Kong, Byung Seon; Kang, Kisuk; Jeon, Seokwoo

2012-06-13

The increasing demand for graphene has required a new route for its mass production without causing extreme damages. Here we demonstrate a simple and cost-effective intercalation based exfoliation method for preparing high quality graphene flakes, which form a stable dispersion in organic solvents without any functionalization and surfactant. Successful intercalation of alkali metal between graphite interlayers through liquid-state diffusion from ternary KCl-NaCl-ZnCl(2) eutectic system is confirmed by X-ray diffraction and X-ray photoelectric spectroscopy. Chemical composition and morphology analyses prove that the graphene flakes preserve their intrinsic properties without any degradation. The graphene flakes remain dispersed in a mixture of pyridine and salts for more than 6 months. We apply these results to produce transparent conducting (∼930 Ω/□ at ∼75% transmission) graphene films using the modified Langmuir-Blodgett method. The overall results suggest that our method can be a scalable (>1 g/batch) and economical route for the synthesis of nonoxidized graphene flakes.

Flaking behavior and microstructure evolution of nickel and copper powder during mechanical milling in liquid environment

Energy Technology Data Exchange (ETDEWEB)

Xiao Xiao [College of Metallurgical Science and Engineering, Central South University, Changsha 410083, Hunan (China); Changsha Research Institute of Mining and Metallurgy, Changsha 410012, Hunan (China); Zeng Zigao [Changsha Research Institute of Mining and Metallurgy, Changsha 410012, Hunan (China); Zhao Zhongwei [College of Metallurgical Science and Engineering, Central South University, Changsha 410083, Hunan (China); Xiao Songwen [Changsha Research Institute of Mining and Metallurgy, Changsha 410012, Hunan (China)], E-mail: swinxiao@yahoo.com.cn

2008-02-25

To prepare metal flakes with a high flaking level and investigate the microstructure of metal flakes, nickel and copper powder were mechanically milled in liquid environment and the microstructure of powders was investigated by X-ray diffraction. The milling process can be divided into flaking and broken stages. At the flaking stage, milled metal powders exhibited high flaking level and flaky microshape, and <2 0 0> became preferred orientation. While at the broken stage, the milled powders presented a low flaking level and irregular microshape, and <2 0 0> was not preferred orientation any longer. The grain size, microstrain and dislocation density along <2 0 0> direction varied with milling time differently from that along <1 1 1> direction. The flaking level of the milled powders was related to the <2 0 0> preferred orientation, and more closely to the deformation mechanism. We can strengthen the formation of <2 0 0> preferred orientation to obtain metal powders with a high flaking level.

Influence of cooling rate on microstructure of NdFeB strip casting flakes

Energy Technology Data Exchange (ETDEWEB)

Binglin Guo; Bo Li; Dongling Wang; Xiaojun Yu [Central Iron and Steel Research Inst., Beijing, BJ (China); Jifan Hu [Shandong Univ., Jinan (China)

2005-07-01

In this paper, flakes of NdFeB cast alloys were prepared by using the strip casting technique. Microstructure and composition of phases in NdFeB SC flakes were studied by SEM and energy spectra. Especially, the influences of cooling rate on the microstructure of SC flakes were discussed, helping us to master strip casting technology. The results show that the cooling rate plays an important role in obtaining the perfect microstructure of SC flakes, which thickness is supposed not less than 0.32mm in these studies. (orig.)

Shape-dependent electronic properties of blue phosphorene nano-flakes

Energy Technology Data Exchange (ETDEWEB)

Bhatia, Pradeep; Swaroop, Ram; Kumar, Ashok, E-mail: ashok@cup.ac.in [Center for Physical Sciences, School of Basic and Applied Sciences, Central University of Punjab, Bathinda-151001 (India)

2016-05-06

In recent year’s considerable attention has been given to the first principles method for modifying and controlling electronic properties of nano-materials. We performed DFT-based calculations on the electronic properties of zigzag-edged nano-flakes of blue phosphorene with three possible shapes namely rectangular, triangular and hexagonal. We observed that HOMO-LUMO gap of zigzag phosphorene nano-flakes with different shapes is ∼2.9 eV with H-passivations and ∼0.7 – 1.2 eV in pristine cases. Electronic properties of blue phosphorene nano-flakes show the strong dependence on their shape. We observed that distributions of molecular orbitals were strongly affected by the different shapes. Zigzag edged considered nanostructures are non-magnetic and semiconducting in nature. The shape dependent electronic properties may find applications in tunable nano-electronics.

The repetitive flaking of Inconel 625 by 100 keV helium bombardment

International Nuclear Information System (INIS)

Whitton, J.L.; Chen, H.M.; Littmark, U.

1981-01-01

Repetitive flaking of Inconel 625 occurs with ion bombardment doses of > than 10 18 100 keV helium ions cm -2 , with up to 39 exfoliations being observed after bombardment with 3 x 10 19 ions cm -2 . The thickness of the flakes, measured by scanning electron microscopy, is some 30% greater than when measured by Rutherford backscattering (RBS) of 1.8 MeV helium ions. These RBS measurements compare well with the thickness of the remaining layers in the resultant craters and to the most probable range of the 100 keV helium. The area of the flakes is dictated by the grain boundaries, and when one flake is ejected, the adjacent grains are prevented from doing so since there now exists an escape route for the injected helium. A strong dose rate dependence is observed; decreasing the beam current from 640 μA cm -2 to 64 μA cm -2 results in a factor 20 fewer flakes being exfoliated (for the same total dose of 3 x 10 19 ions cm -2 ). Successive flakes decrease in area, suggesting that eventually a cratered, but stable, surface will result with the only erosion being by the much less effective mechanism of sputtering. (orig.)

Fire effects on flaked stone, ground stone, and other stone artifacts [Chapter 4

Science.gov (United States)

Krista Deal

2012-01-01

Lithic artifacts can be divided into two broad classes, flaked stone and ground stone, that overlap depending on the defining criteria. For this discussion, flaked stone is used to describe objects that cut, scrape, pierce, saw, hack, etch, drill, or perforate, and the debris (debitage) created when these items are manufactured. Objects made of flaked stone include...

Substitution of Acetylene Black by Using Modified Flake Graphite Applied in Activated Carbon Supercapacitors

Directory of Open Access Journals (Sweden)

Zhao Peng

2018-01-01

Full Text Available Flake graphite was mechanically modified at different times in N-methyl pyrrolidone under normal pressure. The results of the scanning electron microscopy, X-ray diffraction, and transmission electron microscopy suggested that the structure of the flake graphite was modified. The crystallinity of the flake graphite, and many defects were introduced into the material. The evaluation of capacitor performance by cyclic voltammetry, galvanostatic charge/discharge tests, and electrochemical impedance spectroscopy was also performed. Results showed that the electrochemical performance of flake graphite was strongly enhanced, particularly when it was exfoliated for 6 h. Moreover, the electrochemical capacitive properties of activated carbon were obviously enhanced through the substitution of acetylene black by flake graphite modified for 6 h.

Flexural properties and impact strength of denture base resins reinforced with micronized glass flakes

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Ronak H Choksi

2016-01-01

Conclusion: Flexural strength of unmodified PMMA denture base resin decreases with increase in the concentration of glass flakes. Impact strength does not show any significant change at 5% concentration of glass flakes and impact strength significantly reduces with the addition of glass flakes in 10% and 20%.

Chaotic behavior appearing in dynamic motions of nanoscale particles

Energy Technology Data Exchange (ETDEWEB)

Ishikawa, M [Innovation Plaza Tokai, Japan Science and Technology Agency, 23-1 Ahara-cho, Minami-ku, Nagoya 457-0063 (Japan); Harada, R [Department of Physics, Aichi University of Education, Hirosawa 1, Igaya-cho, Kariya 448-8542 (Japan); Kato, M [Innovation Plaza Tokai, Japan Science and Technology Agency, 23-1 Ahara-cho, Minami-ku, Nagoya 457-0063 (Japan); Sasaki, N [Department of Applied Physics, Faculty of Science and Engineering, Seikei University, 3-3-1 Kichijoji Kitamachi, Musashino-shi, Tokyo 180-8633 (Japan); Miura, K [Innovation Plaza Tokai, Japan Science and Technology Agency, 23-1 Ahara-cho, Minami-ku, Nagoya 457-0063 (Japan)

2007-11-15

The case of one-directional motion, under which graphite and mica flakes are driven on an octamethylcyclotetrasiloxane (OMCTS) liquid surface, is presented. The dynamical forces needed to move these bodies increase linearly with the logarithm of scanning velocity, which are typical energy dissipation process. A transition from quasi-periodic to chaotic motions occurs in the dynamics of a graphite flake when its velocity is increased. The dynamics of graphite flakes pulled by the nanotip on an OMCTS liquid surface can be treated as that of a nanobody on a liquid. On the other hand, there do not appear chaotic motions in the dynamics of a mica flake because the contact area between a mica flake and an OMCTS liquid surface is larger than that between a graphite flake and an OMCTS liquid surface.

Chaotic behavior appearing in dynamic motions of nanoscale particles

International Nuclear Information System (INIS)

Ishikawa, M; Harada, R; Kato, M; Sasaki, N; Miura, K

2007-01-01

The case of one-directional motion, under which graphite and mica flakes are driven on an octamethylcyclotetrasiloxane (OMCTS) liquid surface, is presented. The dynamical forces needed to move these bodies increase linearly with the logarithm of scanning velocity, which are typical energy dissipation process. A transition from quasi-periodic to chaotic motions occurs in the dynamics of a graphite flake when its velocity is increased. The dynamics of graphite flakes pulled by the nanotip on an OMCTS liquid surface can be treated as that of a nanobody on a liquid. On the other hand, there do not appear chaotic motions in the dynamics of a mica flake because the contact area between a mica flake and an OMCTS liquid surface is larger than that between a graphite flake and an OMCTS liquid surface

Chaotic behavior appearing in dynamic motions of nanoscale particles

Science.gov (United States)

Ishikawa, M.; Harada, R.; Kato, M.; Sasaki, N.; Miura, K.

2007-11-01

The case of one-directional motion, under which graphite and mica flakes are driven on an octamethylcyclotetrasiloxane (OMCTS) liquid surface, is presented. The dynamical forces needed to move these bodies increase linearly with the logarithm of scanning velocity, which are typical energy dissipation process. A transition from quasi-periodic to chaotic motions occurs in the dynamics of a graphite flake when its velocity is increased. The dynamics of graphite flakes pulled by the nanotip on an OMCTS liquid surface can be treated as that of a nanobody on a liquid. On the other hand, there do not appear chaotic motions in the dynamics of a mica flake because the contact area between a mica flake and an OMCTS liquid surface is larger than that between a graphite flake and an OMCTS liquid surface.

Significance of antifouling paint flakes to the distribution of dichlorodiphenyltrichloroethanes (DDTs) in estuarine sediment

International Nuclear Information System (INIS)

Wu, Chen-Chou; Bao, Lian-Jun; Tao, Shu; Zeng, Eddy Y.

2016-01-01

Recently published literature indicated that dichlorodiphenyltrichloroethane (DDT)-containing antifouling paint flakes were heterogeneously distributed within estuarine sediments. However, the significance of antifouling paint flakes in the fate and transport of DDT compounds and other organic pollutants in estuarine sediment is yet to be adequately addressed. To fill this knowledge gap, estuarine sediment and paint flakes from cabin and boat surfaces were collected from a fishery base in Guangdong Province of South China and analyzed for DDT compounds. Coarse fractioned samples collected from the vicinity of boat maintenance facilities contained appreciable amounts of colorful particles, which were identified as paint flakes by Fourier transform infrared spectroscopy. The highest concentrations of DDXs (sum of DDTs and its metabolites) occurred in the heavy-density (>1.7 g cm"−"3) fraction of coarse-size (200–2000 μm) sediments from near the boat maintenance facilities, suggesting the importance of paint flakes in the distribution pattern of “hot spots” in estuarine sediment. Moreover, the desorption rates of DDT compounds from paint flakes and the heavy-density fraction of coarse-size sediment were both extremely slow. Apparently, unevenly distributed paint flakes in sediment can artificially inflate the sorption capacity of heavy-density sediment for DDT compounds, and therefore can substantially change the environmental fate and behavior of hydrophobic organic chemicals in estuarine sediment. Finally, commonly used source diagnostic indices of DDT compounds were mostly grain-size and density dependent in sediment, as a result of the occurrence of paint flakes, which may strongly compromise the outcome of any source diagnostics efforts. - Highlights: • Concentrations of DDTs were elevated in coarse and high-density fractions. • The desorption rates of DDTs from coarse and high-density fraction were extreme slow. • DDTs-containing antifouling

Oxidative fabrication of patterned, large, non-flaking CuO nanowire arrays

International Nuclear Information System (INIS)

Mumm, F; Sikorski, P

2011-01-01

We report a simple and fast approach to fabricate large, non-flaking arrays of CuO nanowires by oxidizing thin copper substrates in air. Oxidative CuO nanowire growth is commonly accompanied by oxide layer flaking due to stress at the copper-copper oxide interface. Using thin substrates is shown to prevent this flaking by introducing favourable material thickness ratios in the samples after oxidation. Additionally, thin foils allow larger scale topographic patterns to be transferred from an underlying mould to realize non-flat, nanowire-decorated surfaces. Further patterning is possible by electrodeposition of a nickel layer, which restricts nanowire growth to specific areas of the sample.

Ab initio study of friction of graphene flake on graphene/graphite or SiC surface

Science.gov (United States)

Gulseren, Oguz; Tayran, Ceren; Sayin, Ceren Sibel

Recently, the rich dynamics of graphene flake on graphite or SiC surfaces are revealed from atomic force microcopy experiments. The studies toward to the understanding of microscopic origin of friction are getting a lot of attention. Despite the several studies of these systems using molecular dynamics methods, density functional theory based investigations are limited because of the huge system sizes. In this study, we investigated the frictional force on graphene flake on graphite or SiC surfaces from pseudopotential planewave calculations based on density functional theory. In both cases, graphene flake (24 C) on graphite or SiC surface, bilayer flake is introduced by freezing the top layer as well as the bottom layer of the surface slab. After fixing the load with these frozen layers, we checked the relative motion of the flake over the surface. A minimum energy is reached when the flake is moved on graphene to attain AB stacking. We also conclude that edge reconstruction because of the finite size of the flake is very critical for frictional properties of the flake; therefore the saturation of dangling bonds with hydrogen is also addressed. Not only the symmetric configurations remaining parameter space is extensively studied. Supported by TUBITAK Project No: 114F162. This work is supported by TUBITAK Project No: 114F162.

Rumen undegradable protein (RUP) and its intestinal digestibility after steam flaking of cereal grains

DEFF Research Database (Denmark)

Chrenková, M; Formelová, Z; Ceresnáková, Z

2018-01-01

While it is known that heat treatment of cereal grains generally improves the nutritional value for ruminants, simultaneous information on rumen degradability and intestinal digestibility of the rumen by-pass is scarce, especially for non-starch constituents. The effect of steam flaking at 90°C...... flaking on chemical composition of cereal grains (crude protein, acid detergent fibre, neutral detergent fibre, and starch) were observed. The protein fractions that are relevant to rumen degradability were significantly influenced by the steam flaking: the non-protein nitrogen fraction (A) was reduced (P...... hand, steam flaking markedly increased buffer insoluble but neutral detergent soluble protein fraction (B2) by 15–25% for all three cereal grains, whereas effects on B3 fraction were not significant. Steam flaking was also associated with an increase of the rumen undegradable protein fraction (C...

Graphene interfaced perovskite solar cells: Role of graphene flake size

Science.gov (United States)

Sakorikar, Tushar; Kavitha, M. K.; Tong, Shi Wun; Vayalamkuzhi, Pramitha; Loh, Kian Ping; Jaiswal, Manu

2018-04-01

Graphene interfaced inverted planar heterojunction perovskite solar cells are fabricated by facile solution method and studied its potential as hole conducting layer. Reduced graphene oxide (rGO) with small and large flake size and Polyethylenedioxythiophene:polystyrene sulfonate (PEDOT:PSS) are utilized as hole conducting layers in different devices. For the solar cell employing PEDOT:PSS as hole conducting layer, 3.8 % photoconversion efficiency is achieved. In case of solar cells fabricated with rGO as hole conducting layer, the efficiency of the device is strongly dependent on flake size. With all other fabrication conditions kept constant, the efficiency of graphene-interfaced solar cell improves by a factor of 6, by changing the flake size of graphene oxide. We attribute this effect to uniform coverage of graphene layer and improved electrical percolation network.

Dating simple flakes: Early Bronze Age flake production technology on the Middle Euphrates Steppe, Syria

Directory of Open Access Journals (Sweden)

Yoshihiro Nishiaki

2014-03-01

Full Text Available Aceramic flint scatters, comprising very crude cores or flakes and no formalised tools, are frequently found on the Middle Euphrates steppe of northern Syria. Previous studies suggest that many of them are residues of short-term activities by the nomads or shepherds of the Early Bronze Age. In order to verify this interpretation, a more precise chronological framework needs to be established for the Early Bronze Age lithic industry. This paper analyses stratified flake assemblages of the Early Bronze Age at Tell Ghanem al-Ali, a securely radiocarbon-dated settlement on the Middle Euphrates, and examines which occupation level yields assemblages most similar to those of the steppe. Results demonstrate that the lithic industry of this period underwent significant diachronic changes in terms of core reduction technology. Based on the chronological framework developed at Tell Ghanem al-Ali, the steppe assemblages in question can be assigned to different phases of the Early Bronze Age. This finding will help identify processes at the beginning of the extensive exploitation of the steppe, which is regarded as one of the most important socioeconomic changes that occurred among Early Bronze Age communities of the Middle Euphrates.

Numerical study of friction of flake and adsorbed monolayer on atomically clean substrate

International Nuclear Information System (INIS)

Matsukawa, Hiroshi; Haraguchi, Kazuhiro; Ozaki, Shinsuke

2007-01-01

Frictional behaviors of flake and adsorbed monolayer on substrate can be observed by Frictional force microscope and Quartz crystal microbalance experiments and are typical problems in nano-friction. Computer simulations had been played important roles in understanding those behaviors, but in most of them the driving direction coincides with one of the crystal axes of the substrate. Here we report our numerical results of direction dependence of friction of flake and adsorbed monolayer. We found a new kind of dynamical phase transition in which flake and adsorbed monlayer change their structure relative to the substrate and make incommensurae structure to reduce kinetic frictional force after certain transition time. When the driving velocity is decreased the transition time tends to diverge at certain critical velocity for the flake. For the adsorbed monlayer the transition time tends to diverge at certain critical magnitudes of the external force or the interaction strength between adsorbates when they are decreased

Electromagnetic microwave absorption of Fe–Si flakes with different mixtures

International Nuclear Information System (INIS)

Tian, N.; You, C.Y.; Liu, J.; Qu, F.; Wang, C.H.; Lu, Z.X.

2013-01-01

Flakes of Fe–Si alloy were fabricated to get a relatively high permeability. Additives of graphene, TiO 2 and ZnO were mixed with the Fe–Si flakes. The magnetic properties of the Fe–Si alloy flakes were slightly affected by mixing, causing little decrease of the complex permeability. But the complex permittivity was significantly reduced due to the enhanced interfacial resistivity after mixing with graphene, TiO 2 or ZnO, resulting in a better electromagnetic impedance matching. The best microwave absorption performance was achieved by mixing TiO 2 : for an absorber thickness of 1.5 mm, a minimum reflection loss (RL) of −14.1 dB was obtained at 7.1 GHz with a large width of 3.6 GHz in which the RL is lower than −10 dB; with the absorber thickness of 2.4 mm, the minimum RL reaches −35.3 dB at 4.2 GHz. The different effects among graphene, TiO 2 and ZnO additives on the electromagnetic properties are mainly related to the morphology of the additives rather than their intrinsic characteristics. - Highlights: ► The relative permittivity of pure Fe–Si flakes was reduced by mixing graphene, TiO 2 and ZnO. ► Microwave absorption was improved by physically mixing without permeability loss. ► Sample with TiO 2 shows good microwave absorption with a minimum RL of −35.3 dB at 4.2 GHz

Thermophysical properties and microstructure of graphite flake/copper composites processed by electroless copper coating

International Nuclear Information System (INIS)

Liu, Qian; He, Xin-Bo; Ren, Shu-Bin; Zhang, Chen; Ting-Ting, Liu; Qu, Xuan-Hui

2014-01-01

Highlights: • GF–copper composites were fabricated using a sparking plasma sintering, which involves coating GF with copper, using electroless plating technique. • The oriented graphite flake distributed homogeneously in matrix. • With the increase of flake graphite from 44 to 71 vol.%, the basal plane thermal conductivity of composites increases from 445 to 565 W m −1 K −1 and the thermal expansion of composites decreases from 8.1 to 5.0. • The obtained composites are suitable for electronic packaging materials. -- Abstract: This study focuses on the fabrication of thermal management material for power electronics applications using graphite flake reinforced copper composites. The manufacturing route involved electroless plating of copper on the graphite flake and further spark plasma sintering of composite powders. The relative density of the composites with 44–71 vol.% flakes achieved up to 98%. Measured thermal conductivities and coefficients of thermal expansion of composites ranged from 455–565 W m −1 K −1 and 8 to 5 ppm K −1 , respectively. Obtained graphite flake–copper composites exhibit excellent thermophysical properties to meet the heat dispersion and matching requirements of power electronic devices to the packaging materials

Low-temperature synthesis of nanocrystalline ZrC coatings on flake graphite by molten salts

Energy Technology Data Exchange (ETDEWEB)

Ding, Jun, E-mail: dingjun@wust.edu.cn; Guo, Ding; Deng, Chengji; Zhu, Hongxi; Yu, Chao

2017-06-15

Highlights: • Uniform ZrC coatings are prepared on flake graphite at 900 °C. • ZrC coatings are composed of nanosized (30–50 nm) particles. • The template growth mechanism is believed to be dominant in the molten salt synthesis process. - Abstract: A novel molten salt synthetic route has been developed to prepare nanocrystalline zirconium carbide (ZrC) coatings on flake graphite at 900 °C, using Zr powder and flake graphite as the source materials in a static argon atmosphere, along with molten salts as the media. The effects of different molten salt media, the sintered temperature, and the heat preservation time on the phase and microstructure of the synthetic materials were investigated. The ZrC coatings formed on the flake graphite were uniform and composed of nanosized particles (30–50 nm). With an increase in the reaction temperature, the ZrC nanosized particles were more denser, and the heat preservation time and thickness of the ZrC coating also increased accordingly. Electron microscopy was used to observe the ZrC coatings on the flake graphite, indicating that a “template mechanism” played an important role during the molten salt synthesis.

Use of Kelvin probe force microscopy for identification of CVD grown graphene flakes on copper foil

Science.gov (United States)

Kumar, Rakesh; Mehta, B. R.; Kanjilal, D.

2017-05-01

Graphene flakes have been grown by chemical vapour deposition (CVD) method on Cu foils. The obtained graphene flakes have been characterized by optical microscopy, field emission scanning electron microscopy, Kelvin probe force microscopy (KPFM) and Raman spectroscopy. The graphene flakes grown on Cu foil comprise mainly single layer graphene and confirm that the nucleation for graphene growth starts very quickly. Moreover, KPFM has been found to be a valuable technique to differentiate between covered and uncovered portion of Cu foil by graphene flakes deposited for shorter duration. The results show that KPFM can be a very useful technique in understanding the mechanism of graphene growth.

Molecular beam epitaxy of graphene on mica

International Nuclear Information System (INIS)

Lippert, G.; Dabrowski, J.; Yamamoto, Y.; Mehr, W.; Lupina, G.; Herziger, F.; Maultzsch, J.; Baringhaus, J.; Tegenkamp, C.; Lemme, M.C.

2012-01-01

Realization of graphene devices is often hindered by the fact that the known layer growth methods do not meet the requirements of the device fabrication in silicon mainstream technology. For example, the relatively straightforward method of decomposition of hexagonal SiC is not CMOS-compatible due to the high-thermal budget it requires [Moon et al., IEEE Electron Device Lett. 31, 260 (2010)]. Techniques based on layer transfer are restricted because of the uncertainty of residual metal contaminants, particles, and structural defects. Of interest is thus a method that would allow one to grow a graphene film directly in the device area where graphene is needed. Production of large area graphene is not necessarily required in this case, but high quality of the film and metal-free growth on an insulating substrate at temperatures below 1000 C are important requirements. We demonstrate direct growth of defect-free graphene on insulators at moderate temperatures by molecular beam epitaxy. The quality of the graphene was probed by high-resolution Raman spectroscopy, indicating a negligible density of defects. The spectra are compared with those from graphene flakes mechanically exfoliated from native graphite onto mica. These results are combined with insights from density functional theory calculations. A model of graphene growth on mica and similar substrates is proposed. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Sputtering ultra-small Pt on nanographitic flakes deposited by electrophoresis for ethanol electro oxidation

Science.gov (United States)

Daryakenari, Ahmad Ahmadi; Daryakenari, Mohammad Ahmadi; Omidvar, Hamid

2018-01-01

To acquire highly efficient and cost-effective fuel cells, numerous research works have been carried out to the development low cost and excellent performance of electrocatalysts. In this paper, a solution-based electrophoretic deposition (EPD) technique for fabrication of Pt-based catalyst layers is studied. Nanographitic flake coatings used as catalyst support for sputtered platinium (Pt) were fabricated via the electrophoretic deposition (EPD) of dispersed nanographitic flakes in isopropyl alcohol. Magnesium nitrate hexahydrate (MNH) was used as an additive binder in the EPD process. Subsequently, the platinium particles were deposited by a direct sputtering on the fabricated nanographitic flake coatings.

Thermophysical properties and microstructure of graphite flake/copper composites processed by electroless copper coating

Energy Technology Data Exchange (ETDEWEB)

Liu, Qian; He, Xin-Bo; Ren, Shu-Bin; Zhang, Chen; Ting-Ting, Liu; Qu, Xuan-Hui, E-mail: quxh@ustb.edu.cn

2014-02-25

Highlights: • GF–copper composites were fabricated using a sparking plasma sintering, which involves coating GF with copper, using electroless plating technique. • The oriented graphite flake distributed homogeneously in matrix. • With the increase of flake graphite from 44 to 71 vol.%, the basal plane thermal conductivity of composites increases from 445 to 565 W m{sup −1} K{sup −1} and the thermal expansion of composites decreases from 8.1 to 5.0. • The obtained composites are suitable for electronic packaging materials. -- Abstract: This study focuses on the fabrication of thermal management material for power electronics applications using graphite flake reinforced copper composites. The manufacturing route involved electroless plating of copper on the graphite flake and further spark plasma sintering of composite powders. The relative density of the composites with 44–71 vol.% flakes achieved up to 98%. Measured thermal conductivities and coefficients of thermal expansion of composites ranged from 455–565 W m{sup −1} K{sup −1} and 8 to 5 ppm K{sup −1}, respectively. Obtained graphite flake–copper composites exhibit excellent thermophysical properties to meet the heat dispersion and matching requirements of power electronic devices to the packaging materials.

Nanoscale Characterization of Glass Flake Filled Vinyl Ester Anti-Corrosion Coatings

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Salim Barbhuiya

2017-08-01

Full Text Available Vinyl ester is a thermoset matrix resin that is widely used in the coating industry. The presence of glass flakes further enhances the anti-corrosion performance of this coating. This paper reports the nanoscaled characterization of glass flake filled vinyl ester anti-corrosion coatings on mild steel. Bond strength properties of one uncoated and four coated samples with different thicknesses (300, 600, 900 and 1200 μm were studied using nanoscratch technique and ASTM Standard Test. It was found that the bond strength of coating with thickness 900 μm was the highest. The frequency distributions of elastic modulus on coating with 900 μm thickness determined using nanoindentation indicated that only 20–25% of the coating is composed of glass flakes and the balance is vinyl ester matrix. The critical depth at which the material is subject to failure due to external load and abrasion, was found to be around 100 nm.

Production of High-quality Few-layer Graphene Flakes by Intercalation and Exfoliation

KAUST Repository

Alzahrani, Areej A.

2017-11-30

Graphene, a two-dimensional nanomaterial, has been given much attention since it was first isolated in 2004. Driving this intensive research effort are the unique properties of this one atom thick sheet of carbon, in particular its electrical, thermal and mechanical properties. While the technological applications proposed for graphene abound, its low-cost production in large scales is still a matter of interrogation. Simple methods to obtain few-layered graphene flakes of high structural quality are being investigated with the exfoliation of graphite taking a prominent place in this arena. From the many suggested approaches, the most promising involve the use of liquid media assisted by intercalants and shear forces acting on the basal layers of graphite. In this thesis, it is discussed how a novel method was developed to produce flakes with consistent lateral dimensions that are also few-layered and retain the expected structural and chemical characteristics of graphene. Here, the source material was a commercially available graphiteintercalated compound, also known as expandable graphite. Several exfoliation-inducing tools were investigated including the use of blenders, homogenizers, and ultrasonic processors. To aid in this process, various solvents and intercalants were explored under different reactive conditions. The more efficient approach in yielding defect-free thin flakes was the use of thermally expanded graphite in boiling dimethylformamide followed by ultrasonic processing and centrifugation. In parallel, a method to fraction the flakes as a function of their lateral size was developed. Ultimately, it was possible to obtain samples of graphene flakes with a lateral dimension of a few micrometers (<5 μm) and thickness of 1-3 nm (i.e. <10 layers).

40 CFR 417.60 - Applicability; description of the manufacture of soap flakes and powders subcategory.

Science.gov (United States)

2010-07-01

... manufacture of soap flakes and powders subcategory. 417.60 Section 417.60 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS SOAP AND DETERGENT MANUFACTURING POINT SOURCE CATEGORY Manufacture of Soap Flakes and Powders Subcategory § 417.60 Applicability...

The different adsorption mechanism of methane molecule onto a boron nitride and a graphene flakes

International Nuclear Information System (INIS)

Seyed-Talebi, Seyedeh Mozhgan; Neek-Amal, M.

2014-01-01

Graphene and single layer hexagonal boron-nitride are two newly discovered 2D materials with wonderful physical properties. Using density functional theory, we study the adsorption mechanism of a methane molecule over a hexagonal flake of single layer hexagonal boron-nitride (h-BN) and compare the results with those of graphene. We found that independent of the used functional in our ab-initio calculations, the adsorption energy in the h-BN flake is larger than that for graphene. Despite of the adsorption energy profile of methane over a graphene flake, we show that there is a long range behavior beyond minimum energy in the adsorption energy of methane over h-BN flake. This result reveals the higher sensitivity of h-BN sheet to the adsorption of a typical closed shell molecule with respect to graphene. The latter gives insight in the recent experiments of graphene over hexagonal boron nitride.

The different adsorption mechanism of methane molecule onto a boron nitride and a graphene flakes

Energy Technology Data Exchange (ETDEWEB)

Seyed-Talebi, Seyedeh Mozhgan [Shahid Chamran University, Golestan boulevard, Ahvaz, Khouzestan (Iran, Islamic Republic of); Neek-Amal, M., E-mail: neekamal@srttu.edu [Shahid Rajaee Teacher Training University, Lavizan, Tehran (Iran, Islamic Republic of)

2014-10-21

Graphene and single layer hexagonal boron-nitride are two newly discovered 2D materials with wonderful physical properties. Using density functional theory, we study the adsorption mechanism of a methane molecule over a hexagonal flake of single layer hexagonal boron-nitride (h-BN) and compare the results with those of graphene. We found that independent of the used functional in our ab-initio calculations, the adsorption energy in the h-BN flake is larger than that for graphene. Despite of the adsorption energy profile of methane over a graphene flake, we show that there is a long range behavior beyond minimum energy in the adsorption energy of methane over h-BN flake. This result reveals the higher sensitivity of h-BN sheet to the adsorption of a typical closed shell molecule with respect to graphene. The latter gives insight in the recent experiments of graphene over hexagonal boron nitride.

Reliable Exfoliation of Large-Area High-Quality Flakes of Graphene and Other Two-Dimensional Materials.

Science.gov (United States)

Huang, Yuan; Sutter, Eli; Shi, Norman N; Zheng, Jiabao; Yang, Tianzhong; Englund, Dirk; Gao, Hong-Jun; Sutter, Peter

2015-11-24

Mechanical exfoliation has been a key enabler of the exploration of the properties of two-dimensional materials, such as graphene, by providing routine access to high-quality material. The original exfoliation method, which remained largely unchanged during the past decade, provides relatively small flakes with moderate yield. Here, we report a modified approach for exfoliating thin monolayer and few-layer flakes from layered crystals. Our method introduces two process steps that enhance and homogenize the adhesion force between the outermost sheet in contact with a substrate: Prior to exfoliation, ambient adsorbates are effectively removed from the substrate by oxygen plasma cleaning, and an additional heat treatment maximizes the uniform contact area at the interface between the source crystal and the substrate. For graphene exfoliation, these simple process steps increased the yield and the area of the transferred flakes by more than 50 times compared to the established exfoliation methods. Raman and AFM characterization shows that the graphene flakes are of similar high quality as those obtained in previous reports. Graphene field-effect devices were fabricated and measured with back-gating and solution top-gating, yielding mobilities of ∼4000 and 12,000 cm(2)/(V s), respectively, and thus demonstrating excellent electrical properties. Experiments with other layered crystals, e.g., a bismuth strontium calcium copper oxide (BSCCO) superconductor, show enhancements in exfoliation yield and flake area similar to those for graphene, suggesting that our modified exfoliation method provides an effective way for producing large area, high-quality flakes of a wide range of 2D materials.

Sorption isotherms for oat flakes (Avena sativa L.

Directory of Open Access Journals (Sweden)

José Edgar Zapata M.

2014-04-01

Full Text Available Moisture sorption isotherms of oat flakes were determined at temperatures of 5, 25 and 37°C, using a gravimetric technique in an a w range of between 0.107 and 0.855. These curves were modeled using six equations commonly applied in food. The quality of the fit was assessed with the regression coefficient (r² and the mean relative percentage error (MRPE. The best fit were obtained with the Caurie model with r² of 0.996, 0.901 and 0.870, and MRPE of 7.190, 17.878 and 16.206, at 5, 25 and 37°C, respectively. The equilibrium moisture presented a dependence on temperature in the studied a w range, as did the security moisture (X S. These results suggest that the recommended storage conditions of oat flakes include: a relative air humidity of 50% between 5 and 25°C and of 38% up to 37°C.

Physical and sensory properties of corn flakes with added dry residue of wild oregano distillation

Directory of Open Access Journals (Sweden)

Košutić Milenko

2016-01-01

Full Text Available According to the modern nutritionist opinions, cereal products such as flakes and snacks are the most common foods in the daily diet. Extrusion technology makes it possible to apply different sources of ingredients for the enrichment of cereal-based flakes or snack products. Substances with strong antioxidant properties such as wild oregano have a positive impact on human health. Therefore, they attract the attention of scientists, consumers and food industry experts. This paper investigates the effects of the simultaneous addition of dry residue from wild oregano distillation (0.5 g / 100g of sample and 1 g / 100g of sample, on the physical-textural and color properties of corn flakes in order to create a new product with improved nutritional properties. The addition of dry residue of wild oregano positively influenced physical characteristics (decreased bulk density 30.2 %, increased expansion rate 44.9 %, as well as texture hardness and the work of compression, 38.1 % and 40.3 %, respectively. Also, oregano significantly changed the color of flakes. Tukey’s HSD test showed statistically significant differences between most of the mean values of physical-textural, color and sensory attributes in the oregano-added corn flakes compared to the control sample. Principal component analysis has been applied to classify the samples according to differences in the studied parameters. The data pointed out that investigated corn flakes with the addition of wild oregano are new food products with good physical-textural and sensory properties due to a higher level of antioxidant activity. Moreover, it may contribute to the valorization of edible industrial waste in food production. [Projekat Ministarstva nauke Republike Srbije, br. III 46005 i br. TR 31027

Study of hot corrosion of flakes of non purified graphite and of purified graphite

International Nuclear Information System (INIS)

Boule, Michel

1967-01-01

The author reports the study of hot corrosion of the Ticonderoga graphite. He reports the study of the defects of graphite flakes (structure defects due to impurities), the dosing of these impurities, and then their removal by purification. Flakes have then been oxidised by means of a specially designed apparatus. Based on photographs taken by optical and electronic microscopy, the author compares the oxidation features obtained in dry air and in humid air, between purified and non purified flakes. He also reports the study of the evolution of oxidation with respect to the initial rate of impurities, and the study of the evolution of oxidation features in humid air during oxidation. All these comparisons are made while taking the oxidation rate into account [fr

FORMULASI FLAKES TEPUNG KOMPOSIT PATI GARUT DAN TEPUNG SINGKONG DENGAN PENAMBAHAN PEGAGAN SEBAGAI PANGAN FUNGSIONAL SARAPAN ANAK SEKOLAH DASAR

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Daniel Pratama Sianturi

2014-08-01

Full Text Available ABSTRACTGotu Kola is a herbal plant that can improve cognitive ability. This study aims to find a flakes formulas of composite flour of arrowroot starch and cassava flour with addition of gotu kola as a functional food for elementary school children’s breakfast. The tests show that the final selected formula flakes (FTA are the flakes made of 60% arrowroot starch, 40% of cassava flour, with 2.5% addition of gotu kola. Acceptance test show that 91.67% of consumer target accept FTA. The results of physical analysis show that FTA have 51.04 g/mmof hardness, 273.79% of water absorption, and 0.13 g/ml of bulk density. The results of nutrition content analysis show that FTA contained 3.28% of water, 1.35% of ash, 0.43% of fat, 3.09% of protein, 91.86% of carbohydrate, and 384 kcal of energy, 11.33 mg/100 g of Ca, 5.93 mg/100 g of Fe, and 52.45 mg/100 g of P. Nutrient contributions of flakes FTA against RDA of children aged elementary school are 6.39—8.39% for energy, 1.80—3.09% for protein, 0.21—0.24% for fat, 11.13—14.61% for carbohydrate, 0.33—0.40% for Ca, 14.83—25.95% for Fe, and 1.47—3.67% for P.Keywords: arrowroot starch, breakfast, cassava flour, flakes, gotu kolaABSTRAKPegagan merupakan tanaman herbal yang dapat meningkatkan kemampuan kognitif. Tujuan dari penelitian ini adalah mendapatkan formula flakes dari tepung komposit pati garut dan tepung singkong dengan penambahan pegagan sebagai pangan fungsional untuk sarapan anak sekolah dasar. Hasil pengujian menunjukkan bahwa flakes formula terpilih akhir (FTA adalah flakes yang terbuat dari 60% pati garut, 40% tepung singkong, dan dengan penambahan pegagan sebesar 2.5%. Uji penerimaan juga dilakukan terhadap flakes FTA, dan sebanyak 91.67% konsumen sasaran dapat menerima flakes FTA. Hasil analisis sifat fisik menunjukkan bahwa flakes FTA memiliki kekerasan sebesar 51.04 g/mm, daya serap air sebesar 273.79%, dan densitas kamba sebesar 0.13 g/ml. Hasil analisis kandungan gizi

Large-scale synthesis of hierarchical-structured weissite (Cu2−xTe) flake arrays and their catalytic properties

International Nuclear Information System (INIS)

Cao, Xinjiang; Yan, Shancheng; Ortiz, Lazarus Santiago; Liang, Gaofeng; Sun, Bo; Huang, Ningping; Xiao, Zhongdang

2014-01-01

Graphical abstract: - Highlights: • Large-scale Cu 2−x Te flake arrays grown on copper foam were synthesized. • They possess superior catalytic efficiency on methylene blue with the assistance of H 2 O 2 . • The effects of preparing conditions on the growth of Cu 2−x Te flake arrays were investigated. - Abstract: Large-scale weissite (Cu 2−x Te) flake arrays with three-dimensional (3D) hierarchical structure have been successfully fabricated via a facile one-step solution-phase strategy through the reaction of tellurium powder and copper foam. At the end of the reaction Cu 2−x Te flakes were distributed evenly on the surface of a porous solid copper substrate. Field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analysis showed the abundance of flakes grown on the 3D porous copper architecture, while X-ray diffraction (XRD) and energy-dispersive X-ray spectra (EDS) were used to determine the crystal structure and phase composition of these products. A series of experiments discovered that the size and morphology of the products could be affected by some reactive parameters including the reaction time, synthesis temperature and volume ratio of absolute ethanol/deionized water. Catalysis experiments using the in situ synthesized of Cu 2−x Te flakes to catalyze the degradation of methylene blue (MB) demonstrated the strong catalytic ability of these flakes

Quantifying lithic microwear with load variation on experimental basalt flakes using LSCM and area-scale fractal complexity (Asfc)

International Nuclear Information System (INIS)

Stemp, W James; Morozov, Mikhail; Key, Alastair J M

2015-01-01

Working load is one factor that affects wear on stone tools. Despite the recognition of the importance of the relationship between working load and the development of microwear on stone tools, there have been few attempts to quantify differences in wear due to changes in load. In a controlled experiment, we used 30 basalt flakes knapped from raw material collected in Olduvai Gorge, Tanzania, Africa, to cut oak branches for the same number of strokes. For each flake, a different loading level was applied starting at 150 g and increasing by increments of 150 g to a maximum load of 4.5 kg. A laser scanning confocal microscope was used to mathematically document the surface texture of the flakes. The worn surface data were compared using area-scale fractal complexity (Asfc), calculated from relative areas, to determine the degree to which variation in loading significantly affected the amount of wear on the flake surfaces. Our results indicate that working load does play a role in the development of lithic microwear on these flakes and that discrimination of two worn flake surfaces, using mean square ratios of Asfc, based on variable load is consistently possible with load differences between ∼100 g and 4.5 kg. However, discrimination of microwear on flake surfaces was not consistent for all load level differences and discrimination became less consistent when working load differences were below ∼100 g. (paper)

Preparation and characterization of flake graphite/silicon/carbon spherical composite as anode materials for lithium-ion batteries

International Nuclear Information System (INIS)

Lai Jun; Guo Huajun; Wang Zhixing; Li Xinhai; Zhang Xiaoping; Wu Feixiang; Yue Peng

2012-01-01

Highlights: ► Flake graphite/silicon/carbon composite is synthesized via spray drying. ► Flake graphite of ∼0.5 μm and glucose are used to prepare the composite. ► The as-prepared composite shows spherical and porous appearance. ► The composite shows nearly the same cycleability as commercial graphite in 20 cycles. ► The composite shows a reversible capacity of 552 mAh/g at the 20th cycle. - Abstract: Using nano-Si, glucose and flake graphite of ∼0.5 μm as raw materials, flake graphite/silicon/carbon composite is successfully synthesized via spray drying and subsequent pyrolysis. The samples are characterized by XRD, SEM, TEM and electrochemical measurements. The composite is composed of flake graphite, nano-Si and amorphous glucose-pyrolyzed carbon and presents good spherical appearance. Some micron pores arising from the decomposition of glucose exist on the surface of the composite particles. The composite has a high reversible capacity of 602.7 mAh/g with an initial coulombic efficiency of 69.71%, and shows nearly the same cycleability as the commercial graphite in 20 cycles. Both the glucose-pyrolyzed carbon and the micron pores play important roles in improving the cycleability of the composite. The flake graphite/silicon/carbon composite electrode is a potential alternative to graphite for high energy-density lithium ion batteries.

Karakteristik Kimia dan Organoleptik Flakes Kacang Hijau dengan Penambahan Bahan Pengisi dan Air

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Maya Indra Rasyid

2016-04-01

Full Text Available (Chemical and Organoleptic Characteristics of Mung Bean Flakes with The Addition of Fillers and Water  ABSTRACT. The objective of this research was to determine the chemical and organoleptic characteristics of mung bean flakes with the addition of fillers and water. The study was conducted using completely randomized design with two factors namely the addition of fillers and water. The results showed that the addition of fillers and water has significant (P≤0,01 effect on the water absorption ratio and protein levels of mung bean flakes. The best treatment was obtained by the mung bean flour without the addition of fillers with 150% of addition water with water absorption ratio of 204%, water content of 5,7%, protein of 22,01%, starch levels of 61,76%, organoleptic values of aroma of 2,61, color of 2,42, crispness of 2,72 and flavor of 2,83.

METABOLIC AND BIOCHEMICAL CHARACTERISTICS OF PROBIOTIC CULTURE IN MILK SUPPLEMENTED WITH RYE FLAKES AND MALT EXTRACT

Directory of Open Access Journals (Sweden)

Elena Bărăscu

2010-01-01

Full Text Available Rye flakes and malt extract were added to milk in order to stimulate growth and fermentative activity of probioticbacteria and to obtain a probiotic product with pleasant sensory attributes. Probiotic culture used in this study containsbifidobacteria, Lb. acidophilus, Lactobacilus lactis and Streptococcus thermophilus.Rye flakes have a stimulating effect more pronounced than malt extract on acidification capacity of the probioticculture, and to achieve an increase of the milk acidity of 7g lactic acid /dm3 (in 6h at 39oC the two ingredients must beadded in concentration of 2% and, respectively, 0.2%..The probiotic culture reach the greatest proteolytic activity when rye flakes are added in the proportion of 3% andmalt extract in the proportion of 0.1% and the amino acids released rate was 764.6 μg%. The lactose bioconversionrate was greater in the milk supplemented with rye flakes 3% and malt extract 0.1% and residual lactose was 3.84%.

Preparation and characterization of flake graphite/silicon/carbon spherical composite as anode materials for lithium-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Lai Jun [School of Metallurgical Science and Engineering, Central South University, Changsha 410083 (China); Guo Huajun, E-mail: Lai_jun_@126.com [School of Metallurgical Science and Engineering, Central South University, Changsha 410083 (China); Wang Zhixing; Li Xinhai; Zhang Xiaoping; Wu Feixiang; Yue Peng [School of Metallurgical Science and Engineering, Central South University, Changsha 410083 (China)

2012-07-25

Highlights: Black-Right-Pointing-Pointer Flake graphite/silicon/carbon composite is synthesized via spray drying. Black-Right-Pointing-Pointer Flake graphite of {approx}0.5 {mu}m and glucose are used to prepare the composite. Black-Right-Pointing-Pointer The as-prepared composite shows spherical and porous appearance. Black-Right-Pointing-Pointer The composite shows nearly the same cycleability as commercial graphite in 20 cycles. Black-Right-Pointing-Pointer The composite shows a reversible capacity of 552 mAh/g at the 20th cycle. - Abstract: Using nano-Si, glucose and flake graphite of {approx}0.5 {mu}m as raw materials, flake graphite/silicon/carbon composite is successfully synthesized via spray drying and subsequent pyrolysis. The samples are characterized by XRD, SEM, TEM and electrochemical measurements. The composite is composed of flake graphite, nano-Si and amorphous glucose-pyrolyzed carbon and presents good spherical appearance. Some micron pores arising from the decomposition of glucose exist on the surface of the composite particles. The composite has a high reversible capacity of 602.7 mAh/g with an initial coulombic efficiency of 69.71%, and shows nearly the same cycleability as the commercial graphite in 20 cycles. Both the glucose-pyrolyzed carbon and the micron pores play important roles in improving the cycleability of the composite. The flake graphite/silicon/carbon composite electrode is a potential alternative to graphite for high energy-density lithium ion batteries.

Large-scale synthesis of hierarchical-structured weissite (Cu{sub 2−x}Te) flake arrays and their catalytic properties

Energy Technology Data Exchange (ETDEWEB)

Cao, Xinjiang [State Key Laboratory of Bioelectronics (Chien-Shiung Wu Lab), School of Biological Science and Medical Engineering, Southeast University, Si Pai Lou 2#, Nanjing 210096 (China); Yan, Shancheng [School of Geography and Biological Information, Nanjing University of Posts and Telecommunications, Nanjing 210046 (China); Ortiz, Lazarus Santiago; Liang, Gaofeng; Sun, Bo; Huang, Ningping [State Key Laboratory of Bioelectronics (Chien-Shiung Wu Lab), School of Biological Science and Medical Engineering, Southeast University, Si Pai Lou 2#, Nanjing 210096 (China); Xiao, Zhongdang, E-mail: zdxiao@seu.edu.cn [State Key Laboratory of Bioelectronics (Chien-Shiung Wu Lab), School of Biological Science and Medical Engineering, Southeast University, Si Pai Lou 2#, Nanjing 210096 (China)

2014-03-01

Graphical abstract: - Highlights: • Large-scale Cu{sub 2−x}Te flake arrays grown on copper foam were synthesized. • They possess superior catalytic efficiency on methylene blue with the assistance of H{sub 2}O{sub 2}. • The effects of preparing conditions on the growth of Cu{sub 2−x}Te flake arrays were investigated. - Abstract: Large-scale weissite (Cu{sub 2−x}Te) flake arrays with three-dimensional (3D) hierarchical structure have been successfully fabricated via a facile one-step solution-phase strategy through the reaction of tellurium powder and copper foam. At the end of the reaction Cu{sub 2−x}Te flakes were distributed evenly on the surface of a porous solid copper substrate. Field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analysis showed the abundance of flakes grown on the 3D porous copper architecture, while X-ray diffraction (XRD) and energy-dispersive X-ray spectra (EDS) were used to determine the crystal structure and phase composition of these products. A series of experiments discovered that the size and morphology of the products could be affected by some reactive parameters including the reaction time, synthesis temperature and volume ratio of absolute ethanol/deionized water. Catalysis experiments using the in situ synthesized of Cu{sub 2−x}Te flakes to catalyze the degradation of methylene blue (MB) demonstrated the strong catalytic ability of these flakes.

Coating of graphite flakes with MgO/carbon nanocomposite via gas state reaction

International Nuclear Information System (INIS)

Sharif, M.; Faghihi-Sani, M.A.; Golestani-Fard, F.; Saberi, A.; Soltani, Ali Khalife

2010-01-01

Coating of graphite flakes with MgO/carbon nanocomposite was carried out via gaseous state reaction between mixture of Mg metal, CO gas and graphite flakes at 1000 o C. XRD and FE-SEM analysis of coating showed that the coating was comprised of MgO nano particles and amorphous carbon distributed smoothly and covered the graphite surface evenly. Thermodynamic calculations were employed to predict the reaction sequences as well as phase stability. The effect of coating on water wettability and oxidation resistance of graphite was studied using contact angle measurement and TG analysis, respectively. It was demonstrated that the reaction between Mg and CO could result in MgO/C nanocomposite deposition. The coating improved water wettability of graphite and also enhanced the oxidation resistance of graphite flakes significantly. Also the graphite coating showed significant phenolic resin-wettabilty owing to high surface area of such hydrophilic nano composite coating. The importance of graphite coating is explained with emphasis on its potential application in graphite containing refractories.

Determination of the lateral size and thickness of solution-processed graphene flakes

Science.gov (United States)

Lin, Li-Shang; Bin-Tay, Wei; Aslam, Zabeada; Westwood, A. V. K.; Brydson, R.

2017-09-01

We present a method to determine the lateral size distribution of solution…processed graphene via direct image analysis techniques. Initially transmission electron microscopy (TEM) and optical microscopy (OM) were correlated and used to provide a reliable benchmark. A rapid, automated OM method was then developed to obtain the distribution from thousands of flakes, avoiding statistical uncertainties and providing high accuracy. Dynamic light scattering (DLS) was further employed to develop an in-situ method to derive the number particle size distribution (PSD) for a dispersion, with a deviation lower than 22% in the sub-micron regime. Methods for determining flake thickness are also discussed.

Basic properties of full-size st ructural flakeboards fabricated with flakes on a shaping lathe

Science.gov (United States)

Eddie W. Prie

1977-01-01

Structural exterior flakeboards manufactured in 4 by 8 ft (1.22 by 2.44 m ) size with phenolic resin and flakes produced on a shaping-lathe headrig were evaluated for plate shear modulus, internal bond, bending properties, and 24-hour water soak stability. Both mixed and single species flakeboards were produced. Panels with mixed flakes had 20% by weight of hickory,...

Formation and filtration of flakes from coal slurries

Energy Technology Data Exchange (ETDEWEB)

Sing, B K; Clement, M; Juentgen, H

1977-06-01

Size and size distribution of flakes are much influenced by the type and concentration of the flocculation agent. The coal particles show different behaviour to that of the dirt particles. The ph-value and the concentration of electrolytes also influence flocculation. They change the surface properties of the solid material as well as the flocculability of the flocculant.

An excellent performance anode of ZnFe2O4/flake graphite composite for lithium ion battery

International Nuclear Information System (INIS)

Yao, Lingmin; Hou, Xianhua; Hu, Shejun; Tang, Xiaoqin; Liu, Xiang; Ru, Qiang

2014-01-01

Highlights: • ZnFe 2 O 4 /flake graphite composite was synthesized by hydrothermal method. • The ZnFe 2 O 4 /flake graphite anode demonstrated high initial coulombic efficiency of 87.7%. • The initial discharge /charge capacity was 848 mA h g −1 and 744 mA h g −1 . • The high capacity retention of 98% was obtained for the ZnFe 2 O 4 /flake graphite anode. -- Abstract: An approach of hydrothermal reaction for lithium ion battery was adopted, by which ZnFe 2 O 4 /flake graphite composites with excellent performance could be prepared as anode materials for lithium ion batteries. With nano-sized ZnFe 2 O 4 particles coating on the electrochemical active matrix of flake graphite, the special composites allowed improved electronic conductivity and constructed an expressway for the transport of charges and lithium ions. Thus the ZnFe 2 O 4 /flake graphite anode became a compromise between capacity and cycle ability. The initial discharge–charge capacity was 848 mA h g −1 and 744 mA h g −1 at a constant current density of 100 mA g −1 , respectively. As high as 87.7% of the initial coulombic efficiency was obtained. Additionally, the charge capacity maintained constantly in the range of 720–735 mA h g −1 in following cycles. And a high reversible charge capacity of 730 mA h g −1 could be attained after 100 cycles, with the reversible capacity retention of 98%

Investigation of surface potentials in reduced graphene oxide flake by Kelvin probe force microscopy

Science.gov (United States)

Negishi, Ryota; Takashima, Kai; Kobayashi, Yoshihiro

2018-06-01

The surface potential (SP) of reduced graphene oxide (rGO) flakes prepared by thermal treatments of GO under several conditions was analyzed by Kelvin probe force microscopy. The low-crystalline rGO flakes in which a significant amount of oxygen functional groups and structural defects remain have a much lower SP than mechanically exfoliated graphene free from oxygen and defects. On the other hand, the highly crystalline rGO flake after a thermal treatment for the efficient removal of oxygen functional groups and healing of structural defects except for domain boundary shows SP equivalent to that of the mechanically exfoliated graphene. These results indicate that the work function of rGO is sensitively modulated by oxygen functional groups and structural defects remaining after the thermal reduction process, but is not affected significantly by the domain boundary remaining after the healing of structural defects through the thermal treatment at high temperature.

Morphology and magnetic properties of CeCo5 submicron flakes prepared by surfactant-assisted high-energy ball milling

International Nuclear Information System (INIS)

Zhang, J.J.; Gao, H.M.; Yan, Y.; Bai, X.; Su, F.; Wang, W.Q.; Du, X.B.

2012-01-01

CeCo 5 permanent magnetic alloy has been processed by surfactant assisted high energy ball milling. Heptane and oleic acid were used as the solvent and surfactant, respectively. The amount of surfactant used was 50% by weight of the starting powder. The produced particles were deposited on a piece of copper (4 mm in length and width) under a magnetic field of 27 kOe applied along the copper surface and immobilized by ethyl α-cyanoacrylate. Scanning electron microscope pictures show that the particles are flakes, several μm in length and width and tens of nm in thickness. X-ray diffraction patterns and magnetic measurements prove that the flakes are crystalline with c-axes magnetic anisotropy. The easy magnetization axis is oriented perpendicular to the surface of the flake. A maximum coercivity of 3.3 kOe was obtained for the sample milled for 40 min. - Highlights: ► CeCo 5 permanent magnetic alloy has been processed by surfactant assisted high energy ball milling (HEBM). ► The particles show a flake-like morphology with several μm in length and width and tens nm in thickness. ► The flakes are crystallographic and magnetic anisotropic and the c-axes, also the easy magnetization directions are oriented perpendicular to the surface of the flake. ► Maximum coercivity of 3.3 kOe has been obtained for the sample milled for 40 min.

Magnetisation oscillations, boundary conditions and the Hofstadter butterfly in graphene flakes

Energy Technology Data Exchange (ETDEWEB)

Liu, Yang; Brada, Matej; Kusmartsev, Feodor V. [Department of Physics, Loughborough University (United Kingdom); Mele, Eugene J. [Department of Physics, Loughborough University (United Kingdom); Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA (United States)

2014-10-15

New quantum oscillations in the magnetization of graphene flakes induced by magnetic fields, which depend on the shape of the flake, are described. At small values of the field they are due to the Aharonov-Bohm effect and with increasing field they are transformed into dHvA oscillations. The specific form of the dHvA oscillations is analyzed in terms of their energy spectrum, which has a form of Hofstadter's butterfly. Numerical results using a lattice tight-binding model and a continuum Dirac equation are presented and compared. Possible experiments to investigate the quantum oscillations in Moire and graphene anti-dot superlattices are discussed. (copyright 2014 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Coating of graphite flakes with MgO/carbon nanocomposite via gas state reaction

Energy Technology Data Exchange (ETDEWEB)

Sharif, M., E-mail: Sharif_m@metaleng.iust.ac.i [Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Faghihi-Sani, M.A. [Sharif University of Technology, Tehran (Iran, Islamic Republic of); Golestani-Fard, F. [Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Saberi, A. [Tabriz University (Iran, Islamic Republic of); Soltani, Ali Khalife [Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)

2010-06-18

Coating of graphite flakes with MgO/carbon nanocomposite was carried out via gaseous state reaction between mixture of Mg metal, CO gas and graphite flakes at 1000 {sup o}C. XRD and FE-SEM analysis of coating showed that the coating was comprised of MgO nano particles and amorphous carbon distributed smoothly and covered the graphite surface evenly. Thermodynamic calculations were employed to predict the reaction sequences as well as phase stability. The effect of coating on water wettability and oxidation resistance of graphite was studied using contact angle measurement and TG analysis, respectively. It was demonstrated that the reaction between Mg and CO could result in MgO/C nanocomposite deposition. The coating improved water wettability of graphite and also enhanced the oxidation resistance of graphite flakes significantly. Also the graphite coating showed significant phenolic resin-wettabilty owing to high surface area of such hydrophilic nano composite coating. The importance of graphite coating is explained with emphasis on its potential application in graphite containing refractories.

9 CFR 590.547 - Albumen flake process drying operations.

Science.gov (United States)

2010-01-01

... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Albumen flake process drying operations. 590.547 Section 590.547 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE... free of flies, insects, and rodents. (b) Drying units, racks, and trucks shall be kept in a clean and...

FORMULASI FLAKES TEPUNG KOMPOSIT PATI GARUT DAN TEPUNG SINGKONG DENGAN PENAMBAHAN PEGAGAN SEBAGAI PANGAN FUNGSIONAL SARAPAN ANAK SEKOLAH DASAR

OpenAIRE

Daniel Pratama Sianturi; Sri Anna Marliyati

2014-01-01

ABSTRACTGotu Kola is a herbal plant that can improve cognitive ability. This study aims to find a flakes formulas of composite flour of arrowroot starch and cassava flour with addition of gotu kola as a functional food for elementary school children’s breakfast. The tests show that the final selected formula flakes (FTA) are the flakes made of 60% arrowroot starch, 40% of cassava flour, with 2.5% addition of gotu kola. Acceptance test show that 91.67% of consumer target accept FTA. The result...

Techniques for tritium recovery from carbon flakes and dust at the JET active gas handling system

International Nuclear Information System (INIS)

Gruenhagen, S.; Perevezentsev, A.; Brennan, P. D.; Camp, P.; Knipe, S.; Miller, A.; Yorkshades, J.

2008-01-01

Detritiation of highly tritium contaminated carbon and metal material used as first wall armour is a key issue for fusion machines like JET and ITER. Re-deposited carbon and hydrogen in the form of flakes and dust can lead to a build-up of the tritium inventory and therefore this material must be removed and processed. The high tritium concentration of the flake and dust material collected from the JET vacuum vessel makes it unsuitable for direct waste disposal without detritiation. A dedicated facility to process the tritiated carbon flake material and recover the tritium has been designed and built. In several test runs active material was successfully processed and de-tritiated in the new facility. Samples containing only carbon and hydrogen isotopes have been completely oxidized without any residue. Samples containing metallic impurities, e.g. beryllium, require longer processing times, adjusted processing parameters and yield an oxide residue. The detritiation factor was 2x10 4 . In order to simulate in-vessel and ex-vessel detritiation techniques, the detritiation of a carbon flake sample by isotopic exchange in a hydrogen atmosphere was investigated. 2.8% of tritium was recovered by this means. (authors)

Life history of a large flake biface

Science.gov (United States)

Baena Preysler, Javier; Torres Navas, Concepción; Sharon, Gonen

2018-06-01

Bifaces, primarily handaxes and cleavers, are the hallmark of the Acheulian techno-complex lithic industry. They spread across Africa and Eurasia during the Early to Middle Pleistocene. While many attempts have been made to define and describe the typology and technology of these tools, most focus on a single stage in their manufacture and usage, from quarry to discard. These attempts are fragmented, primarily due to the fact that at no single site are all stages of biface manufacture and use represented. An additional factor that appears to impede attempts to present the full "life cycle" of bifaces is the view of all Acheulian assemblages as belonging to a single cultural entity. While all assemblages belong to the same techno-complex, distinct stages and phases should be recognized, each different in typology, technology, and probably also in chronology. This research focuses on the large flake stage of the Acheulian. Data accumulated over many years of research from different regions are analyzed together in an attempt to present a holistic view of the life cycle of a biface. The study of particular Acheulian sites from the Levant and Western Europe enables us to reconstruct all stages of the biface, from raw material exploitation to final discard. The result is a model more comprehensive and precise than those suggested previously for understanding the Large Flake Acheulian.

Catalyst-Free Growth of Three-Dimensional Graphene Flakes and Graphene/g-C₃N₄ Composite for Hydrocarbon Oxidation.

Science.gov (United States)

Chen, Ke; Chai, Zhigang; Li, Cong; Shi, Liurong; Liu, Mengxi; Xie, Qin; Zhang, Yanfeng; Xu, Dongsheng; Manivannan, Ayyakkannu; Liu, Zhongfan

2016-03-22

Mass production of high-quality graphene flakes is important for commercial applications. Graphene microsheets have been produced on an industrial scale by chemical and liquid-phase exfoliation of graphite. However, strong-interaction-induced interlayer aggregation usually leads to the degradation of their intrinsic properties. Moreover, the crystallinity or layer-thickness controllability is not so perfect to fulfill the requirement for advanced technologies. Herein, we report a quartz-powder-derived chemical vapor deposition growth of three-dimensional (3D) high-quality graphene flakes and demonstrate the fabrication and application of graphene/g-C3N4 composites. The graphene flakes obtained after the removal of growth substrates exhibit the 3D curved microstructure, controllable layer thickness, good crystallinity, as well as weak interlayer interactions suitable for preventing the interlayer stacking. Benefiting from this, we achieved the direct synthesis of g-C3N4 on purified graphene flakes to form the uniform graphene/g-C3N4 composite, which provides efficient electron transfer interfaces to boost its catalytic oxidation activity of cycloalkane with relatively high yield, good selectivity, and reliable stability.

Morphology and magnetic properties of CeCo{sub 5} submicron flakes prepared by surfactant-assisted high-energy ball milling

Energy Technology Data Exchange (ETDEWEB)

Zhang, J.J.; Gao, H.M.; Yan, Y.; Bai, X.; Su, F.; Wang, W.Q. [State key Laboratory for Superhard Materials and Department of Physics, Jilin University, Changchun 130012 (China); Du, X.B., E-mail: duxb@jlu.edu.cn [State key Laboratory for Superhard Materials and Department of Physics, Jilin University, Changchun 130012 (China)

2012-10-15

CeCo{sub 5} permanent magnetic alloy has been processed by surfactant assisted high energy ball milling. Heptane and oleic acid were used as the solvent and surfactant, respectively. The amount of surfactant used was 50% by weight of the starting powder. The produced particles were deposited on a piece of copper (4 mm in length and width) under a magnetic field of 27 kOe applied along the copper surface and immobilized by ethyl {alpha}-cyanoacrylate. Scanning electron microscope pictures show that the particles are flakes, several {mu}m in length and width and tens of nm in thickness. X-ray diffraction patterns and magnetic measurements prove that the flakes are crystalline with c-axes magnetic anisotropy. The easy magnetization axis is oriented perpendicular to the surface of the flake. A maximum coercivity of 3.3 kOe was obtained for the sample milled for 40 min. - Highlights: Black-Right-Pointing-Pointer CeCo{sub 5} permanent magnetic alloy has been processed by surfactant assisted high energy ball milling (HEBM). Black-Right-Pointing-Pointer The particles show a flake-like morphology with several {mu}m in length and width and tens nm in thickness. Black-Right-Pointing-Pointer The flakes are crystallographic and magnetic anisotropic and the c-axes, also the easy magnetization directions are oriented perpendicular to the surface of the flake. Black-Right-Pointing-Pointer Maximum coercivity of 3.3 kOe has been obtained for the sample milled for 40 min.

How similar are nut-cracking and stone-flaking? A functional approach to percussive technology.

Science.gov (United States)

Bril, Blandine; Parry, Ross; Dietrich, Gilles

2015-11-19

Various authors have suggested similarities between tool use in early hominins and chimpanzees. This has been particularly evident in studies of nut-cracking which is considered to be the most complex skill exhibited by wild apes, and has also been interpreted as a precursor of more complex stone-flaking abilities. It has been argued that there is no major qualitative difference between what the chimpanzee does when he cracks a nut and what early hominins did when they detached a flake from a core. In this paper, similarities and differences between skills involved in stone-flaking and nut-cracking are explored through an experimental protocol with human subjects performing both tasks. We suggest that a 'functional' approach to percussive action, based on the distinction between functional parameters that characterize each task and parameters that characterize the agent's actions and movements, is a fruitful method for understanding those constraints which need to be mastered to perform each task successfully, and subsequently, the nature of skill involved in both tasks. © 2015 The Author(s).

Erosion and Soil Contamination Control Using Coconut Flakes And Plantation Of Centella Asiatica And Chrysopogon Zizanioides

Science.gov (United States)

Roslan, Rasyikin; Che Omar, Rohayu; Nor Zuliana Baharuddin, Intan; Zulkarnain, M. S.; Hanafiah, M. I. M.

2016-11-01

Land degradation in Malaysia due to water erosion and water logging cause of loss of organic matter, biodiversity and slope instability but also land are contaminated with heavy metals. Various alternative such as physical remediation are use but it not showing the sustainability in term of environmental sustainable. Due to that, erosion and soil contamination control using coconut flakes and plantation of Centella asiatica and Chrysopogon zizanioides are use as alternative approach for aid of sophisticated green technology known as phytoremediation and mycoremediation. Soil from cabonaceous phyllite located near to Equine Park, Sri Kembangan are use for monitoring the effect of phytoremediation and mycoremediation in reducing soil contamination and biotechnology for erosion control. Five laboratory scale prototypes were designed to monitor the effect of different proportion of coconut flakes i.e. 10%, 25%, 50% & 100% and plantation of Centella asiatica and Chrysopogon zizanioides to reduce the top soil from eroding and reduce the soil contamination. Prototype have been observe started from first week and ends after 12 weeks. Centella asiatica planted on 10% coconut flakes with 90% soil and Chrysopogon zizanioides planted on 25% coconut flakes with 75% soil are selected proportion to be used as phytoremediation and mycoremediation in reducing soil contamination and biotechnology for erosion control.

Flaking and wave-like structure on metallic glasses induced by MeV-energy helium ions

International Nuclear Information System (INIS)

Paszti, F.; Fried, M.; Pogany, L.; Manuaba, A.; Mezey, G.; Kotai, E.; Lovas, I.; Lohner, T.; Pocs, L.

1982-11-01

Ten samples prepared from different kinds of metallic glasses (different in composition and manufacturing technology) were bombarded by 2 or 1 MeV helium ions with high fluence under different experimental circumstances. During bombardment the temperature increase of the samples caused by irradiation heating was estimated and kept below the temperature needed for the investigated metallic glass to be crystallized. In all cases the surface deformation processes were dominated by flaking i.e. nearly from the whole implanted area a layer suddenly flaked off with a uniform thickness of the applied ion projected range. The surface left behind the flaked layer can be characterized by a wave-like structure i.e. by a regular series of asymmetrical elevations. These elevations, which did not appear on the annealed samples, are caused by a mechanism developed during the bombardment of the amorphous structure (of metallic glasses) by high energy helium ions. Details of this unusual phenomenon are discussed. (author)

[Study of enzymes of xenobiotic metabolism in the evaluation of quality of protein-containing wheat germ flakes and wallpaper flour].

Science.gov (United States)

Martinchuk, A N; E En Gyn; Safronova, A M; Peskova, E V

1991-01-01

Intake of wheat upholstery meal by growing rats was attended by a sharp decrease in the content and activity of xenobiotic metabolism enzymes in the hepatic microsomes, that was caused by the low biological value of the meal proteins. Hepatic microsomes of the rats that were fed with wheat germ flakes showed increased specific content of cytochromes P-450 and b5, but the total blood protein content per 100 g of body mass was lower than during casein consumption. No significant changes were detected in hydroxylation rate of benz(a)pyrene, aniline and ethylmorphine. During consumption of wheat germ flakes induction of UDP-glucuronide-transferase was detected in hepatic microsomes. Wheat germ flakes induced a 5-fold increase of Se-dependent glutathione peroxidase activity. Wheat germ flakes produced no significant effect on glutathione-S-aryltransferase and glutathione reductase activity.

Formulation of novel trehalose flakes for storage and delivery of ...

African Journals Online (AJOL)

The findings from the present study showed the vaccine flakes are easily transported and readily released into a fluid phase when mixed with water; they can be administered orally without mixing with feeds and hence suitable for individual or mass vaccination of semi-feral scavenging village chickens. Chickens vaccinated ...

Manufacture and characterization of a yogurt-like beverage made with oat flakes fermented by selected lactic acid bacteria.

Science.gov (United States)

Luana, Nionelli; Rossana, Coda; Curiel, José Antonio; Kaisa, Poutanen; Marco, Gobbetti; Rizzello, Carlo Giuseppe

2014-08-18

This study aimed at investigating the suitability of oat flakes for making functional beverages. Different technological options were assayed, including the amount of flakes, the inoculum of the starter and the addition of enzyme preparations. The beverage containing 25% (wt/wt) of oat flakes and fermented with L. plantarum LP09 was considered optimal on the basis of sensory and technological properties. The enzyme addition favored the growth of the starter, shortened the time needed to reach pH4.2 to ca. 8h, and favored a decrease of the quotient of fermentation. Fermentation increased the polyphenols availability and the antioxidant activity (25 and 70% higher, respectively) and decreased the hydrolysis index in vitro. Sensory analyses showed that fermented oat flakes beverage had the typical features of a yogurt-like beverage, enhancing the overall intensity of odor and flavor compared to the non-fermented control. Selection of proper processing and fermentation condition allowed the obtainment of a beverage with better nutritional and sensory properties. Copyright © 2014 Elsevier B.V. All rights reserved.

Investigation of transfer characteristics of high performance graphene flakes.

Science.gov (United States)

Venugopal, Gunasekaran; Krishnamoorthy, Karthikeyan; Kim, Sang-Jae

2013-05-01

In this article, we attempted a study on field effect transport characteristics of graphene flakes. These graphene flakes were exfoliated by mechanical peeling-off technique and the electrical contacts were patterned by photo-lithographic method. Graphene devices have shown better transfer characteristics which was obtained even in low-voltage (graphene transistors were patterned on oxidized silicon wafers. A clear n-type to p-type transition at Dirac point and higher electron drain-current modulation in positive back-gate field with current minimum (the Dirac point) were observed at V(GS) = -1.7 V. The carrier mobility was determined from the measured transconductance. The transconductance of the graphene transistors was observed as high as 18.6 microS with a channel length of 68 microm. A maximum electron mobility of 1870 +/- 143 cm2/V x s and hole mobility of 1050 +/- 35 cm2/V x s were achieved at a drain bias 2.1 V which are comparatively higher values among reported for mechanically exfoliated graphene using lithographic method. The fabricated devices also sustained with high-current density for 40 hr in continuous operation without any change in device resistance, which could be applied for robust wiring applications.

75 FR 36673 - Notice of Inventory Completion: Public Museum of West Michigan, Grand Rapids, MI

Science.gov (United States)

2010-06-28

... of mica fragments, 1 lot of flint flakes, 1 copper nugget, 1 vial of pyrite, 4 vials of sand, 2 vials... objects are 1 lot of copper nuggets, 1 spear point, 2 bone fragments, 2 drills, 2 flakes, 3 knives, 2... red ochre, 1 shell bracelet, 1 lot of bird bone, 1 flint flake, and 1 projectile point fragment. At an...

Verbenone-releasing flakes protect individual Pinus contorta trees from attack by Dendroctonus ponderosae and Dendroctonus valens (Coleoptera: Curculionidae, Scolytinae)

Science.gov (United States)

Nancy E. Gillette; John D. Stein; Donald R. Owen; Jeffrey N. Webster; Gary O. Fiddler; Sylvia R. Mori; David L. Wood

2006-01-01

In a study site in interior northern California, twenty individual lodgepole pines Pinus contorta were sprayed with a suspension of DISRUPT Micro-Flake ® Verbenone (4,6,6-trimethylbicyclo(3.1)hept-3-en-2-one) Bark Beetle Anti-Aggregant flakes (Hercon Environmental, Emigsville, Pennsylvania) in water, with sticker and...

Transfer of an exfoliated monolayer graphene flake onto an optical fiber end face for erbium-doped fiber laser mode-locking

International Nuclear Information System (INIS)

Rosa, Henrique Guimaraes; De Souza, Eunézio A Thoroh; Gomes, José Carlos Viana

2015-01-01

This paper presents, for the first time, the successful transfer of exfoliated monolayer graphene flake to the optical fiber end face and alignment to its core. By fabricating and optimizing a polymeric poly(methyl methacrylate) (PMMA) and polyvinyl alcohol (PVA) substrate, it is possible to obtain a contrast of up to 11% for green light illumination, allowing the identification of monolayer graphene flakes that were transferred to optical fiber samples and aligned to its core. With Raman spectroscopy, it is demonstrated that graphene flake completely covers the optical fiber core, and its quality remains unaltered after the transfer. The generation of mode-locked erbium-doped fiber laser pulses, with a duration of 672 fs, with a single-monolayer graphene flake as a saturable absorber, is demonstrated for the first time. This transfer technique is of general applicability and can be used for other two-dimensional (2D) exfoliated materials. (letter)

Chondroitin sulfate template-mediated biomimetic synthesis of nano-flake hydroxyapatite

Science.gov (United States)

He, Dan; Xiao, Xiufeng; Liu, Fang; Liu, Rongfang

2008-11-01

By Ca(NO 3) 2·4H 2O and (NH 4) 3PO 4·3H 2O as reagents and chondroitin sulfate (ChS) as a template, nano-flake hydroxyapatite (HA) is synthesized using a biomimetic method according to the biomineralization theory. HA crystals obtained are characterized in crystalline phase, microstructure, chemical composition and morphology by X-ray diffraction (XRD), Fourier transform infrared spectroscope (FTIR), transmission electron microscopy (TEM) and elemental analysis respectively. UV-vis spectrum is adopted to investigate interactions between functional groups ChS and HA. The results show that HA crystal nucleation and growth take place in chemical interactions between HA crystals and ChS as a template. And elemental analysis indicates that obtained HA contains a small amount of ChS. Furthermore, ChS concentration significantly affects the morphology of HA crystals. Staple-fiber-like HA crystals can be obtained at a low concentration in ChS, and flake-like HA crystals synthesized at a high concentration (≥0.5 wt.%) of ChS as a template.

Chondroitin sulfate template-mediated biomimetic synthesis of nano-flake hydroxyapatite

Energy Technology Data Exchange (ETDEWEB)

He Dan; Xiao Xiufeng; Liu Fang [College of Chemistry and Materials Science, Fujian Normal University, Fuzhou 350007 (China); Liu Rongfang [College of Chemistry and Materials Science, Fujian Normal University, Fuzhou 350007 (China)], E-mail: rfliu@vip.sina.com

2008-11-15

By Ca(NO{sub 3}){sub 2}.4H{sub 2}O and (NH{sub 4}){sub 3}PO{sub 4}.3H{sub 2}O as reagents and chondroitin sulfate (ChS) as a template, nano-flake hydroxyapatite (HA) is synthesized using a biomimetic method according to the biomineralization theory. HA crystals obtained are characterized in crystalline phase, microstructure, chemical composition and morphology by X-ray diffraction (XRD), Fourier transform infrared spectroscope (FTIR), transmission electron microscopy (TEM) and elemental analysis respectively. UV-vis spectrum is adopted to investigate interactions between functional groups ChS and HA. The results show that HA crystal nucleation and growth take place in chemical interactions between HA crystals and ChS as a template. And elemental analysis indicates that obtained HA contains a small amount of ChS. Furthermore, ChS concentration significantly affects the morphology of HA crystals. Staple-fiber-like HA crystals can be obtained at a low concentration in ChS, and flake-like HA crystals synthesized at a high concentration ({>=}0.5 wt.%) of ChS as a template.

Effect of commercial breakfast fibre cereals compared with corn flakes on postprandial blood glucose, gastric emptying and satiety in healthy subjects: a randomized blinded crossover trial

Directory of Open Access Journals (Sweden)

Almér Lars-Olof

2007-09-01

Full Text Available Abstract Background Dietary fibre food intake is related to a reduced risk of developing diabetes mellitus. However, the mechanism of this effect is still not clear. The aim of this study was to evaluate the effect of commercial fibre cereals on the rate of gastric emptying, postprandial glucose response and satiety in healthy subjects. Methods Gastric emptying rate (GER was measured by standardized real time ultrasonography. Twelve healthy subjects were assessed using a randomized crossover blinded trial. The subjects were examined after an 8 hour fast and after assessment of normal fasting blood glucose level. Satiety scores were estimated and blood glucose measurements were taken before and at 0, 20, 30, 40, 60, 80, 100 and 120 min after the end of the meal. GER was calculated as the percentage change in the antral cross-sectional area 15 and 90 min after ingestion of sour milk with corn flakes (GER1, cereal bran flakes (GER2 or wholemeal oat flakes (GER3. Results The median value was, respectively, 42% for GER1, 33 % for GER2 and 51% for GER3. The difference between the GER after ingestion of bran flakes compared to wholemeal oat flakes was statistically significant (p = 0.023. The postprandial delta blood glucose level was statistically significantly lower at 40 min (p = 0.045 and 120 min (p = 0.023 after the cereal bran flakes meal. There was no statistical significance between the areas under the curve (AUCs of the cereals as far as blood glucose and satiety were concerned. Conclusion The result of this study demonstrates that the intake of either bran flakes or wholemeal oat flakes has no effect on the total postprandial blood glucose response or satiety when compared to corn flakes. However, the study does show that the intake of cereal bran flakes slows the GER when compared to oat flakes and corn flakes, probably due to a higher fibre content. Since these products do not differ in terms of glucose response and satiety on healthy

Sintering behavior and thermal conductivity of nickel-coated graphite flake/copper composites fabricated by spark plasma sintering

Science.gov (United States)

Xu, Hui; Chen, Jian-hao; Ren, Shu-bin; He, Xin-bo; Qu, Xuan-hui

2018-04-01

Nickel-coated graphite flakes/copper (GN/Cu) composites were fabricated by spark plasma sintering with the surface of graphite flakes (GFs) being modified by Ni-P electroless plating. The effects of the phase transition of the amorphous Ni-P plating and of Ni diffusion into the Cu matrix on the densification behavior, interfacial microstructure, and thermal conductivity (TC) of the GN/Cu composites were systematically investigated. The introduction of Ni-P electroless plating efficiently reduced the densification temperature of uncoated GF/Cu composites from 850 to 650°C and slightly increased the TC of the X-Y basal plane of the GF/Cu composites with 20vol%-30vol% graphite flakes. However, when the graphite flake content was greater than 30vol%, the TC of the GF/Cu composites decreased with the introduction of Ni-P plating as a result of the combined effect of the improved heat-transfer interface with the transition layer, P generated at the interface, and the diffusion of Ni into the matrix. Given the effect of the Ni content on the TC of the Cu matrix and on the interface thermal resistance, a modified effective medium approximation model was used to predict the TC of the prepared GF/Cu composites.

Ex situ integration of iron oxide nanoparticles onto the exfoliated expanded graphite flakes in water suspension

Directory of Open Access Journals (Sweden)

Jović Nataša

2014-01-01

Full Text Available Hybrid structures composed of exfoliated expanded graphite (EG and iron oxide nanocrystals have been produced by an ex situ process. The iron oxide nanoparticles coated with meso-2,3-dimercaptosuccinic acid (DMSA, or poly(acrylic acid (PAA were integrated onto the exfoliated EG flakes by mixing their aqueous suspensions at room temperature under support of 1-ethyl-3-(3-dimethylaminopropylcarbodiimide (EDC and N-hydroxysuccin-nimide (NHS. EG flakes have been used both, naked and functionalized with branched polyethylenimine (PEI. Complete integration of two constituents has been achieved and mainteined stable for more than 12 months. No preferential spatial distribution of anchoring sites for attachement of iron oxide nanoparticles has been observed, regardless EG flakes have been used naked or functionalized with PEI molecules. The structural and physico-chemical characteristics of the exfoliated expanded graphite and its hybrids nanostructures has been investigated by SEM, TEM, FTIR and Raman techniques. [Projekat Ministarstva nauke Republike Srbije, br. 45015

Degradation mechanisms of organic rubber and glass flake/vinyl ester linings in flue gas desulphurization plants

Energy Technology Data Exchange (ETDEWEB)

Weber, R [Allianz-Centre for Technology GmbH, Ismaning (Germany)

1996-12-01

In recent years, there have been reports in numerous publications about damage to rubber and glass flake coatings in flue gas desulphurization plants. The pattern of damage has been described and attempts have frequently been made to determine and explain the cause of the damage. Oxidation/hydrolytic changes were generally observed as the damage mechanisms. In addition, blistering occurs in both the chloroprene coatings in the absorbers and in the glass flake coatings in clean gas ducts. This blistering may be considered as the end of the useful life and leads to cost-intensive and time-intensive repair and restoration measures. The present state of knowledge suggests that the blistering is mainly due to osmotic processes preceded by permeation processes and with permeation processes superimposed on them. Among other things, the reports describe the permeation behaviour of water and other flue gas constituents; the blistering in chloroprene rubber coatings and glass flake coatings is explained by means of the knowledge gained. (au) 16 refs.

Recovery from Iridium-192 flakes of a radioactive source for industrial use after a radiation incident

International Nuclear Information System (INIS)

Cruz, W.H.; Zapata, L.A.

2013-01-01

The Iridium-192 ( 192 Ir) is the most used and ideal for industrial radiography applications, especially in petrochemical plants and pipelines and provides better contrast sensitivity for thick (25.4 mm). This source has constructive sealed double encapsulation, the internal capsule containing stainless steel to radioactive material in the form of flakes and welded with TIG process. The radiological incident happened at a gas station fuel sales in circumstances in which there was a homogeneity test welds a tank, the flakes or Ir-192 fell off his ponytail and left scattered over an area of 2 m 2 , some fell flat areas and other land so collected in lead shielding and metal container and ground source. Full recovery of the leaflets was performed at the Division of radioactive waste management (GRRA) gaining a total of 22 flakes with no radiation risk to staff performance and installation and the conclusion was reached that the misapplicaion of TIG welding was the main cause the incident. (author)

Hydrothermal flake graphite mineralisation in Paleoproterozoic rocks of south-east Greenland

DEFF Research Database (Denmark)

Rosing-Schow, Nanna; Bagas, Leon; Kolb, Jochen

2017-01-01

Flake graphite mineralisation is hosted in the Kuummiut Terrane of the Paleoproterozoic Nagssugtoqidian Orogen, south-east Greenland. Eclogite-facies peak-metamorphic assemblages record temperatures of 640–830 °C and pressures of 22–25 kbar, and are retrogressed in the high-pressure amphibolite-f...

Non-destructive analysis of flake properties in automotive paints with full-field optical coherence tomography and 3D segmentation.

Science.gov (United States)

Zhang, Jinke; Williams, Bryan M; Lawman, Samuel; Atkinson, David; Zhang, Zijian; Shen, Yaochun; Zheng, Yalin

2017-08-07

Automotive coating systems are designed to protect vehicle bodies from corrosion and enhance their aesthetic value. The number, size and orientation of small metallic flakes in the base coat of the paint has a significant effect on the appearance of automotive bodies. It is important for quality assurance (QA) to be able to measure the properties of these small flakes, which are approximately 10μm in radius, yet current QA techniques are limited to measuring layer thickness. We design and develop a time-domain (TD) full-field (FF) optical coherence tomography (OCT) system to scan automotive panels volumetrically, non-destructively and without contact. We develop and integrate a segmentation method to automatically distinguish flakes and allow measurement of their properties. We test our integrated system on nine sections of five panels and demonstrate that this integrated approach can characterise small flakes in automotive coating systems in 3D, calculating the number, size and orientation accurately and consistently. This has the potential to significantly impact QA testing in the automotive industry.

Atomic force microscopy studies on molybdenum disulfide flakes as sodium-ion anodes.

Science.gov (United States)

Lacey, Steven D; Wan, Jiayu; von Wald Cresce, Arthur; Russell, Selena M; Dai, Jiaqi; Bao, Wenzhong; Xu, Kang; Hu, Liangbing

2015-02-11

A microscale battery comprised of mechanically exfoliated molybdenum disulfide (MoS2) flakes with copper connections and a sodium metal reference was created and investigated as an intercalation model using in situ atomic force microscopy in a dry room environment. While an ethylene carbonate-based electrolyte with a low vapor pressure allowed topographical observations in an open cell configuration, the planar microbattery was used to conduct in situ measurements to understand the structural changes and the concomitant solid electrolyte interphase (SEI) formation at the nanoscale. Topographical observations demonstrated permanent wrinkling behavior of MoS2 electrodes upon sodiation at 0.4 V. SEI formation occurred quickly on both flake edges and planes at voltages before sodium intercalation. Force spectroscopy measurements provided quantitative data on the SEI thickness for MoS2 electrodes in sodium-ion batteries for the first time.

Tannic acid assisted synthesis of flake-like hydroxyapatite nanostructures at room temperature

Science.gov (United States)

Vázquez, Maricela Santana; Estevez, O.; Ascencio-Aguirre, F.; Mendoza-Cruz, R.; Bazán-Díaz, L.; Zorrila, C.; Herrera-Becerra, R.

2016-09-01

A simple and non-expensive procedure was performed to synthesize hydroxyapatite (HAp) flake-like nanostructures, by using a co-precipitation method with tannic acid as stabilizing agent at room temperature and freeze drying. Samples were synthesized with two different salts, Ca(NO3)2 and CaCl2. X-ray diffraction analysis, Raman spectroscopy, scanning and transmission electron microscopy characterizations reveal Ca10(PO4)6(OH)2 HAp particles with hexagonal structure and P63/m space group in both cases. In addition, the particle size was smaller than 20 nm. The advantage of this method over the works reported to date lies in the ease for obtaining HAp particles with a single morphology (flakes), in high yield. This opens the possibility of expanding the view to the designing of new composite materials based on the HAp synthesized at room temperature.

Suppression of Magnetoresistance in Thin WTe2 Flakes by Surface Oxidation.

Science.gov (United States)

Woods, John M; Shen, Jie; Kumaravadivel, Piranavan; Pang, Yuan; Xie, Yujun; Pan, Grace A; Li, Min; Altman, Eric I; Lu, Li; Cha, Judy J

2017-07-12

Recent renewed interest in layered transition metal dichalcogenides stems from the exotic electronic phases predicted and observed in the single- and few-layer limit. Realizing these electronic phases requires preserving the desired transport properties down to a monolayer, which is challenging. Surface oxides are known to impart Fermi level pinning or degrade the mobility on a number of different systems, including transition metal dichalcogenides and black phosphorus. Semimetallic WTe 2 exhibits large magnetoresistance due to electron-hole compensation; thus, Fermi level pinning in thin WTe 2 flakes could break the electron-hole balance and suppress the large magnetoresistance. We show that WTe 2 develops an ∼2 nm thick amorphous surface oxide, which shifts the Fermi level by ∼300 meV at the WTe 2 surface. We also observe a dramatic suppression of the magnetoresistance for thin flakes. However, due to the semimetallic nature of WTe 2 , the effects of Fermi level pinning are well screened and are not the dominant cause for the suppression of magnetoresistance, supported by fitting a two-band model to the transport data, which showed the electron and hole carrier densities are balanced down to ∼13 nm. However, the fitting shows a significant decrease of the mobilities of both electrons and holes. We attribute this to the disorder introduced by the amorphous surface oxide layer. Thus, the decrease of mobility is the dominant factor in the suppression of magnetoresistance for thin WTe 2 flakes. Our study highlights the critical need to investigate often unanticipated and sometimes unavoidable extrinsic surface effects on the transport properties of layered dichalcogenides and other 2D materials.

Lathe creates hardwood flakes for manufacture of "super strong" flakeboard

Science.gov (United States)

P. Koch

1973-01-01

Most industry members got their first look at a prototype of the Koch lathe at this year's Southern Forest Products Assn. Machinery Exhibition held in Atlanta. With the residue from this machine, Dr. Peter Koch, project leader at the Southern Forest Experiment Station in Pineville, LA thinks it will be possible to create a flake that can be used for making a...

Charge-Transfer-Induced p-Type Channel in MoS2 Flake Field Effect Transistors.

Science.gov (United States)

Min, Sung-Wook; Yoon, Minho; Yang, Sung Jin; Ko, Kyeong Rok; Im, Seongil

2018-01-31

The two-dimensional transition-metal dichalcogenide semiconductor MoS 2 has received extensive attention for decades because of its outstanding electrical and mechanical properties for next-generation devices. One weakness of MoS 2 , however, is that it shows only n-type conduction, revealing its limitations for homogeneous PN diodes and complementary inverters. Here, we introduce a charge-transfer method to modify the conduction property of MoS 2 from n- to p-type. We initially deposited an n-type InGaZnO (IGZO) film on top of the MoS 2 flake so that electron charges might be transferred from MoS 2 to IGZO during air ambient annealing. As a result, electron charges were depleted in MoS 2 . Such charge depletion lowered the MoS 2 Fermi level, which makes hole conduction favorable in MoS 2 when optimum source/drain electrodes with a high work function are selected. Our IGZO-supported MoS 2 flake field effect transistors (FETs) clearly display channel-type conversion from n- to p-channel in this way. Under short- and long-annealing conditions, n- and p-channel MoS 2 FETs are achieved, respectively, and a low-voltage complementary inverter is demonstrated using both channels in a single MoS 2 flake.

Formation of water-soluble soybean polysaccharides from spent flakes by hydrogen peroxide treatment

DEFF Research Database (Denmark)

Pierce, Brian; Wichmann, Jesper; Tran, Tam H.

2016-01-01

70% of the original insoluble material as high molar mass soluble polysaccharides. A design of experiment was used to quantify the effects of pH, reaction time, and hydrogen peroxide concentration on the reaction yield, average molar mass, and free monosaccharides generated. The resulting product......In this paper we propose a novel chemical process for the generation of water-soluble polysaccharides from soy spent flake, a by-product of the soy food industry. This process entails treatment of spent flake with hydrogen peroxide at an elevated temperature, resulting in the release of more than...... is low in protein, fat, and minerals and contains predominantly water-soluble polysaccharides of high molar mass, including arabinan, type I arabinogalactan, homogalacturonan, xyloglucan, rhamnogalacturonan, and (glucurono)arabinoxylan. This treatment provides a straightforward approach for generation...

Activated Flake Graphite Coated with Pyrolysis Carbon as Promising Anode for Lithium Storage

International Nuclear Information System (INIS)

Chen, Jun; Zou, Guoqiang; Zhang, Yan; Song, Weixin; Hou, Hongshuai; Huang, Zhaodong; Liao, Hanxiao; Li, Simin; Ji, Xiaobo

2016-01-01

A facile route to improve the lithium-storage properties of flake graphite (FG) is proposed through coating pyrolysis carbon from polyvinylidene fluoride (PVDF) assisted by KOH activation. The interplanar distance between the graphene sheets of activated PVDF/FG is enlarged, effectively suppressing the electrode deformation during lithium (de)-intercalation. More edge and porous structures of PVDF/FG arising from KOH activation on graphite flakes contribute to improved electron and ion transport, leading to great improvement in its rate and cycling performances. The initial specific capacity of the activated PVDF/FG is 476.6 mAh g −1 at 50 mA g −1 and when the current increases to 1000 mA g −1 , the value still retains 142.6 mAh g −1 .

Electrolytic exfoliation of graphite in water with multifunctional electrolytes: en route towards high quality, oxide-free graphene flakes.

Science.gov (United States)

Munuera, J M; Paredes, J I; Villar-Rodil, S; Ayán-Varela, M; Martínez-Alonso, A; Tascón, J M D

2016-02-07

Electrolytic--usually referred to as electrochemical--exfoliation of graphite in water under anodic potential holds enormous promise as a simple, green and high-yield method for the mass production of graphene, but currently suffers from several drawbacks that hinder its widespread adoption, one of the most critical being the oxidation and subsequent structural degradation of the carbon lattice that is usually associated with such a production process. To overcome this and other limitations, we introduce and implement the concept of multifunctional electrolytes. The latter are amphiphilic anions (mostly polyaromatic hydrocarbons appended with sulfonate groups) that play different relevant roles as (1) an intercalating electrolyte to trigger exfoliation of graphite into graphene flakes, (2) a dispersant to afford stable aqueous colloidal suspensions of the flakes suitable for further use, (3) a sacrificial agent to prevent graphene oxidation during exfoliation and (4) a linker to promote nanoparticle anchoring on the graphene flakes, yielding functional hybrids. The implementation of this strategy with some selected amphiphiles even furnishes anodically exfoliated graphenes of a quality similar to that of flakes produced by direct, ultrasound- or shear-induced exfoliation of graphite in the liquid phase (i.e., almost oxide- and defect-free). These high quality materials were used for the preparation of catalytically efficient graphene-Pt nanoparticle hybrids, as demonstrated by model reactions (reduction of nitroarenes). The multifunctional performance of these electrolytes is also discussed and rationalized, and a mechanistic picture of their oxidation-preventing ability is proposed. Overall, the present results open the prospect of anodic exfoliation as a competitive method for the production of very high quality graphene flakes.

Properties on the edge: graphene edge energies, edge stresses, edge warping, and the Wulff shape of graphene flakes

International Nuclear Information System (INIS)

Branicio, Paulo S; Jhon, Mark H; Gan, Chee Kwan; Srolovitz, David J

2011-01-01

It has been shown that the broken bonds of an unreconstructed graphene edge generate compressive edge stresses leading to edge warping. Here, we investigate edge energies and edge stresses of graphene nanoribbons with arbitrary orientations from armchair to zigzag, considering both flat and warped edge shapes in the presence and absence of hydrogen. We use the second generation reactive empirical bond order potential to calculate the edge energies and stresses for clean and hydrogenated edges. Using these energies, we perform a Wulff construction to determine the equilibrium shapes of flat graphene flakes as a function of hydrogen chemical potential. While edge stresses for clean, flat edges are compressive, they become tensile if allowed to warp. Conversely, we find that edge energies change little (∼1%) with edge warping. Hydrogenation of the edges virtually eliminates both the edge energy and edge stresses. For warped edges an approximately linear relationship is found between amplitudes and wavelengths. The equilibrium shape of a graphene flake is determined by the value of the hydrogen chemical potential. For very small (and large) values of it the flakes have a nearly hexagonal (dodecagon) shape with zigzag oriented edges, while for intermediate values graphene flakes are found with complex shapes

Evaluation of the lake model FLake over a coastal lagoon during the THAUMEX field campaign

Directory of Open Access Journals (Sweden)

Patrick Le Moigne

2013-10-01

Full Text Available The THAUMEX measurement campaign, carried out during the summer of 2011 in Thau, a coastal lagoon in southern France, focused on episodes of marine breezes. During the campaign, three intensive observation periods (IOPs were conducted and a large amount of data were collected. Subsequently, standalone modelling using the FLake lake model was used, first to assess the surface temperature and the surface energy balance, and second to determine the energy budget of the water column at the measurement site. Surface fluxes were validated against in situ measurements, and it was determined that heat exchanges are dominated by evaporation. We also demonstrated that the model was sensitive to the light extinction coefficient at Thau, due to its shallowness and clarity nature. A heat balance was calculated, and the inclusion of a radiative temperature has improved it, especially by reducing the nocturnal evaporation. The FLake lake model was then evaluated in three-dimensional numerical simulations performed with the Meso-NH mesoscale model, in order to assess the changing structure of the boundary layer above the lagoon during the IOPs more accurately. We highlighted the first time ever when Meso-NH and FLake were coupled and proved the ability of the coupled system to forecast a complex phenomenon but also the importance of the use of the FLake model was pointed out. We demonstrated the impact of the lagoon and more precisely the Lido, a sandy strip of land between the lagoon and the Mediterranean Sea, on the vertical distribution of turbulent kinetic energy, evidence of the turbulence induced by the breeze. This study showed the complementarities between standalone and coupled simulations.

Vertically aligned cobalt hydroxide nano-flake coated electro-etched carbon fiber cloth electrodes for supercapacitors

Science.gov (United States)

Cheng, Qian; Tang, Jie; Zhang, Han; Qin, Lu-Chang

2014-11-01

We describe preparation and characterization of nanostructured electrodes using Co(OH)2 nano-flakes and carbon fiber cloth for supercapacitors. Nanostructured Co(OH)2 flakes are produced by electrodeposition and they are coated onto the electro-etched carbon fiber cloth. A highest specific capacitance of 3404.8 F g-1 and an area-normalized specific capacitance of 3.3 F cm-2 have been obtained from such electrodes. Morphology and structure of the nanostructured electrodes have been characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical properties have been studied by cyclic voltammetry (CV), constant-current charge and discharge, electrochemical impedance spectroscopy (EIS), and long-time cycling.

shaping-lathe headrig yields solid and molded-flake hardwood products

Science.gov (United States)

Peter Koch; R.A. Caughey

1978-01-01

A shaping-lathe headrig, operated one shift daily, can be used to manufacture hardwood cants to be resawed into pallet shook, one-piece and dowel-laminated crossties, posts and rails, and other solid wood products in lengths from 6 to 9 feet. Residual flakes machined by the headrig supply a three-shift operation in which molded pallets and 4- by 8-foot sheets of...

Alteration of biomacromolecule in corn by steam flaking in relation to biodegradation kinetics in ruminant, revealed with vibrational molecular spectroscopy

Science.gov (United States)

Xu, Ningning; Liu, Jianxin; Yu, Peiqiang

2018-02-01

Large scale of steam flaked corn has been used in dairy ration to maintain high milk production level. This study aimed to determine effects of steam flaking on processing-induced intrinsic molecular structure changes that were associated with rumen degradation kinetics and nutrients supply. The advanced vibrational molecular spectroscopy was applied to reveal the processing-induced intrinsic structure changes on a molecular basis. The rumen degradation kinetics and nutrient supply were determined using in situ approach in ruminant livestock system. Raw corn grain (RC) and steam flaked corn grain (SFC) were obtained from two different processing plants. The results showed that (1) Compared to RC, SFC had greater truly digestible non-fiber carbohydrate [tdNFC: 86.8 versus 78.0% dry matter (DM)], but lower truly digestible crude protein [tdCP: 7.7 versus 9.0% DM]. (2) The steam flaking increased (P < 0.01) rumen degradable DM (RDDM) and starch (RDSt), but decreased (P < 0.01) rumen degradable protein (RDP). (3) Molecular absorbance intensities of most carbohydrate biopolymers were greater in SFC (P < 0.01), but protein amides associated molecular spectral intensities were lower (P < 0.01) in SFC. (4). The molecular structure and nutrient interactive study showed that carbohydrate spectral intensities were positively (P < 0.10) associated with RDDM and RDSt and protein amide spectral intensities were positively (P < 0.10) associated with RDP. This results indicated that the steam flaking induced molecular structure changes had an interactive relationship with rumen degradation kinetics.

Morphology and magnetic properties of CeCo5 submicron flakes prepared by surfactant-assisted high-energy ball milling

Science.gov (United States)

Zhang, J. J.; Gao, H. M.; Yan, Y.; Bai, X.; Su, F.; Wang, W. Q.; Du, X. B.

2012-10-01

CeCo5 permanent magnetic alloy has been processed by surfactant assisted high energy ball milling. Heptane and oleic acid were used as the solvent and surfactant, respectively. The amount of surfactant used was 50% by weight of the starting powder. The produced particles were deposited on a piece of copper (4 mm in length and width) under a magnetic field of 27 kOe applied along the copper surface and immobilized by ethyl α-cyanoacrylate. Scanning electron microscope pictures show that the particles are flakes, several μm in length and width and tens of nm in thickness. X-ray diffraction patterns and magnetic measurements prove that the flakes are crystalline with c-axes magnetic anisotropy. The easy magnetization axis is oriented perpendicular to the surface of the flake. A maximum coercivity of 3.3 kOe was obtained for the sample milled for 40 min.

Combustion of Shock-Dispersed Flake Aluminum - High-Speed Visualization

Energy Technology Data Exchange (ETDEWEB)

Neuwald, P; Reichenbach, H; Kuhl, A

2006-06-19

Charges of 0.5 g PETN were used to disperse 1 g of flake aluminum in a rectangular test chamber of 4 liter inner volume and inner dimensions of approximately 10 cm x 10 cm x 40 cm. The subsequent combustion of the flake aluminum with the ambient air in the chamber gave rise to a highly luminous flame. The evolution of the luminous region was studied by means of high-speed cinematography. The high-speed camera is responsive to a broad spectral range in the visible and near infra-red. For a number of tests this response range was narrowed down by means of a band-pass filter with a center wavelength of 488 nm and a half-width of 23 nm. The corresponding images were expected to have a stronger temperature dependence than images obtained without the filter, thus providing better capability to highlight hot-spots. Emission in the range of the pass-band of the filter can be due to continuous thermal radiation from hot Al and Al{sub 2}O{sub 3} particles or to molecular band emission from gaseous AlO. A time-resolving spectrometer was improvised to inspect this topic. The results suggest that AlO emission occurs, but that the continuous spectrum is the dominating effect in our experiments.

Process Optimization for Solid Extraction, Flavor Improvement and Fat Removal in the Production of Soymilk From Full Fat Soy Flakes

Energy Technology Data Exchange (ETDEWEB)

Prawiradjaja, Stanley [Iowa State Univ., Ames, IA (United States)

2003-01-01

Traditionally soymilk has been made with whole soybeans; however, there are other alternative raw ingredients for making soymilk, such as soy flour or full-fat soy flakes. US markets prefer soymilk with little or no beany flavor. modifying the process or using lipoxygenase-free soybeans can be used to achieve this. Unlike the dairy industry, fat reduction in soymilk has been done through formula modification instead of by conventional fat removal (skimming). This project reports the process optimization for solids and protein extraction, flavor improvement and fat removal in the production of 5, 8 and 12 °Brix soymilk from full fat soy flakes and whole soybeans using the Takai soymilk machine. Proximate analyses, and color measurement were conducted in 5, 8 and 12 °Brix soymilk. Descriptive analyses with trained panelists (n = 9) were conducted using 8 and 12 °Brix lipoxygenase-free and high protein blend soy flake soymilks. Rehydration of soy flakes is necessary to prevent agglomeration during processing and increase extractability. As the rehydration temperature increases from 15 to 50 to 85 C, the hexanal concentration was reduced. Enzyme inactivation in soy flakes milk production (measured by hexanal levels) is similar to previous reports with whole soybeans milk production; however, shorter rehydration times can be achieved with soy flakes (5 to 10 minutes) compared to whole beans (8 to 12 hours). Optimum rehydration conditions for a 5, 8 and 12 °Brix soymilk are 50 C for 5 minutes, 85 C for 5 minutes and 85 C for 10 minutes, respectively. In the flavor improvement study of soymilk, the hexanal date showed differences between undeodorized HPSF in contrast to triple null soymilk and no differences between deodorized HPSF in contrast to deodorized triple null. The panelists could not differentiate between the beany, cereal, and painty flavors. However, the panelists responded that the overall aroma of deodorized 8 °Brix triple null and HPSF soymilk are

Alteration of biomacromolecule in corn by steam flaking in relation to biodegradation kinetics in ruminant, revealed with vibrational molecular spectroscopy.

Science.gov (United States)

Xu, Ningning; Liu, Jianxin; Yu, Peiqiang

2018-02-15

Large scale of steam flaked corn has been used in dairy ration to maintain high milk production level. This study aimed to determine effects of steam flaking on processing-induced intrinsic molecular structure changes that were associated with rumen degradation kinetics and nutrients supply. The advanced vibrational molecular spectroscopy was applied to reveal the processing-induced intrinsic structure changes on a molecular basis. The rumen degradation kinetics and nutrient supply were determined using in situ approach in ruminant livestock system. Raw corn grain (RC) and steam flaked corn grain (SFC) were obtained from two different processing plants. The results showed that (1) Compared to RC, SFC had greater truly digestible non-fiber carbohydrate [tdNFC: 86.8 versus 78.0% dry matter (DM)], but lower truly digestible crude protein [tdCP: 7.7 versus 9.0% DM]. (2) The steam flaking increased (PMolecular absorbance intensities of most carbohydrate biopolymers were greater in SFC (Pmolecular spectral intensities were lower (Pmolecular structure and nutrient interactive study showed that carbohydrate spectral intensities were positively (Pmolecular structure changes had an interactive relationship with rumen degradation kinetics. Copyright © 2017 Elsevier B.V. All rights reserved.

Automated sorting of polymer flakes: fluorescence labeling and development of a measurement system prototype.

Science.gov (United States)

Brunner, S; Fomin, P; Kargel, Ch

2015-04-01

The extensive demand and use of plastics in modern life is associated with a significant economical impact and a serious ecological footprint. The production of plastics involves a high energy consumption and CO2 emission as well as the large need for (limited) fossil resources. Due to the high durability of plastics, large amounts of plastic garbage is mounting in overflowing landfills (plus 9.6 million tons in Europe in the year 2012) and plastic debris is floating in the world oceans or waste-to-energy combustion releases even more CO2 plus toxic substances (dioxins, heavy metals) to the atmosphere. The recycling of plastic products after their life cycle can obviously contribute a great deal to the reduction of the environmental and economical impacts. In order to produce high-quality recycling products, mono-fractional compositions of waste polymers are required. However, existing measurement technologies such as near infrared spectroscopy show limitations in the sorting of complex mixtures and different grades of polymers, especially when black plastics are involved. More recently invented technologies based on mid-infrared, Raman spectroscopy or laser-aided spectroscopy are still under development and expected to be rather expensive. A promising approach to put high sorting purities into practice is to label plastic resins with unique combinations of fluorescence markers (tracers). These are incorporated into virgin resins during the manufacturing process at the ppm (or sub ppm) concentration level, just large enough that the fluorescence emissions can be detected with sensitive instrumentation but neither affect the visual appearance nor the mechanical properties of the polymers. In this paper we present the prototype of a measurement and classification system that identifies polymer flakes (mill material of a few millimeters size) located on a conveyor belt in real time based on the emitted fluorescence of incorporated markers. Classification performance

Well-defined flake-like polypyrrole grafted graphene nanosheets composites as electrode materials for supercapacitors with enhanced cycling stability

Science.gov (United States)

Wang, Xue; Wang, Tingmei; Yang, Chao; Li, Haidong; Liu, Peng

2013-12-01

Well-defined flake-like polypyrrole grafted graphene nanosheets composites (PPy-g-GNS) were fabricated by the in-situ chemical oxidative grafting polymerization of pyrrole in the presence of the 4-aminophenyl modified graphene nanosheets (AP-GNS), which were prepared via the coupling reaction of the graphene nanosheets (GNS) with diazonium salt. The flake-like PPy-g-GNS composite showed the high conductivity at room temperature. A maximum discharge capacitance of 191.2 F/g at the scan rate of 10 mV/s could be achieved in the three-electrode cell electrochemical testing in 1.0 mol/L NaNO3 electrolyte solution. It is higher than those of the AP-GNS, pure PPy, and the GNS/PPy composite prepared with the unmodified graphene nanosheets (GNS). The flake-like PPy-g-GNS composites also exhibited the excellent electrochemical stability even after 1000 cycles. It revealed the synergistic effect between the conducting polymer and the carbon-based support.

Method for uniformly distributing carbon flakes in a positive electrode, the electrode made thereby and compositions. [Patent application

Science.gov (United States)

Mrazek, F.C.; Smaga, J.A.; Battles, J.E.

1981-01-19

A positive electrode for a secondary electrochemical cell is described wherein an electrically conductive current collector is in electrical contact with a particulate mixture of gray cast iron and an alkali metal sulfide and an electrolyte including alkali metal halides or alkaline earth metal halides. Also present may be a transition metal sulfide and graphite flakes from the conversion of gray cast iron to iron sulfide. Also disclosed is a method of distributing carbon flakes in a cell wherein there is formed an electrochemical cell of a positive electrode structure of the type described and a suitable electrolyte and a second electrode containing a material capable of alloying with alkali metal ions. The cell is connected to a source of electrical potential to electrochemically convert gray cast iron to an iron sulfide and uniformly to distribute carbon flakes formerly in the gray cast iron throughout the positive electrode while forming an alkali metal alloy in the negative electrode. Also disclosed are compositions useful in preparing positive electrodes.

Theoretical study of nitrogen-doped graphene nanoflakes: Stability and spectroscopy depending on dopant types and flake sizes.

Science.gov (United States)

Lin, Chih-Kai

2018-03-05

As nitrogen-doped graphene has been widely applied in optoelectronic devices and catalytic reactions, in this work we have investigated where the nitrogen atoms tend to reside in the material and how they affect the electron density and spectroscopic properties from a theoretical point of view. DFT calculations on N-doped hexagonal and rectangular graphene nanoflakes (GNFs) showed that nitrogen atoms locating on zigzag edges are obviously more stable than those on armchair edges or inside flakes, and interestingly, the N-hydrogenated pyridine moiety could be preferable to pure pyridine moiety in large models. The UV-vis absorption spectra of these nitrogen-doped GNFs display strong dependence on flake sizes, where the larger flakes have their major peaks in lower energy ranges. Moreover, the spectra exhibit different connections to various dopant types and positions: the graphitic-type dopant species present large variety in absorption profiles, while the pyridinic-type ones show extraordinary uniform stability and spectra independent of dopant positions/numbers and hence are hardly distinguishable from each other. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

Local electronic and electrical properties of functionalized graphene nano flakes

International Nuclear Information System (INIS)

Chutia, Arunabhiram; Sahnoun, Riadh; Deka, Ramesh C.; Zhu, Zhigang; Tsuboi, Hideyuki; Takaba, Hiromitsu; Miyamoto, Akira

2011-01-01

Based on experimental findings models of amorphous graphene related carbon materials were generated using graphene nano flakes. On the optimized structures detailed local electronic properties were investigated using density functional theory. The electrical conductivities of all these models were also estimated using an in-house program based on tight-binding method. The calculated electrical conductivity values of all the models agreed well with the trend of calculated energy gap and graphitic character.

Gold nanoparticles on MoS2 layered crystal flakes

International Nuclear Information System (INIS)

Cao, Wei; Pankratov, Vladimir; Huttula, Marko; Shi, Xinying; Saukko, Sami; Huang, Zhongjia; Zhang, Meng

2015-01-01

Inorganic layered crystal MoS 2 is considered as one of the most promising and efficient semiconductor materials for future transistors, photoelectronics, and electrocatalysis. To boost MoS 2 -based material applications, one direction is to grow physically and chemically reactive nanoparticles onto MoS 2 . Here we report on a simple route to synthesis crystalized MoS 2 –Au complexes. The gold nanoparticles were grown on MoS 2 flakes through a wet method in the oxygen free environment at room temperature. Nanoparticles with diameters varying from 9 nm to 429 nm were controlled by the molar ratios of MoS 2 and HAuCl 4 precursors. MoS 2 host flakes keep intrinsic honeycomb layered structures and the Au nanoparticles cubic-center crystal microstructures. From product chemical states analysis, the synthesis was found driven by redox reactions between the sulphide and the chloroauric acid. Photoluminescence measurement showed that introducing Au nanoparticles onto MoS 2 stacks substantially prompted excitonic transitions of stacks, as an analogy for doping Si wafers with dopants. Such composites may have potential applications in wide ranges similar as the doped Si. - Highlights: • The Au nanoparticles were decorated on MoS 2 in oxygen free ambiences via a wet method. • The Au nanoparticles are size-controllable and crystalized. • Chemical reaction scheme was clarified. • The MoS 2 –Au complexes have strong photoluminescent properties

Facile synthesis of flake-like TiO{sub 2}/C nano-composites for photocatalytic H{sub 2} evolution under visible-light irradiation

Energy Technology Data Exchange (ETDEWEB)

Yan, Baolin; Zhou, Juan; Liang, Xiaoyu; Song, Kainan; Su, Xintai, E-mail: suxintai827@163.com

2017-01-15

Highlights: • TiO{sub 2}/C nano-flakes were prepared by a facile phase-transfer strategy combined with salt-template calcination method. • The sub–10 nm of TiO{sub 2} NPs were uniformly dispersed on the carbon flakes. • The TiO{sub 2}/C nano-flakes showed a superior visible-light photocatalytic activity for H{sub 2} production. - Abstract: The production of H{sub 2} by photocatalytic water splitting has become a promising approach for clean, economical, and renewable evolution of H{sub 2} by using solar energy. In spite of tremendous efforts, the present challenge for materials scientists is to build a highly active photocatalytic system with high efficiency and low cost. Here we report a facile method for the preparation of TiO{sub 2}/C nano-flakes, which was used as an efficient visible-light photocatalyst for H{sub 2} evolution. This composite material was prepared by using a phase-transfer strategy combined with salt-template calcination treatment. The results showed that anatase TiO{sub 2} nanoparticles with the diameter of ∼10 nm were uniformly dispersed on the carbon nano-flakes. In addition, the samples prepared at 600 °C (denoted as T600) endowed a larger surface area of 196 m{sup 2} g{sup −1} and higher light absorption, resulting in enhanced photocatalytic activity. Further, the T600 product reached a high H{sub 2} production rate of 57.2 μmol h{sup −1} under visible-light irradiation. This unusual photocatalytic activity arose from the positive synergetic effect between the TiO{sub 2} and carbon in this hybrid catalyst. This work highlights the potential of TiO{sub 2}/C nano-flakes in the field of photocatalytic H{sub 2} evolution under visible-light irradiation.

Acetone improves the topographical homogeneity of liquid phase exfoliated few-layer black phosphorus flakes.

Science.gov (United States)

Gomez Perez, Juan; Konya, Zoltan; Kukovecz, Akos

2018-06-12

Liquid phase exfoliation of 2D materials has issues related to the sorption of the solvent, the oxidation of the sample during storage, and the topographical inhomogeneity of the exfoliated material. N-methyl-2-pyrrolidone (NMP), a common solvent for black phosphorus (BP) exfoliation, has additional drawbacks like the formation of by-products during sonication and poor solvent volatility. Here we demonstrate an improvement in the topographical homogeneity (i.e. thickness and lateral dimensions) of NMP-exfoliated BP flakes after resuspension in acetone. The typical size of monolayers and bilayers stabilised in acetone was 99.8±27.4 nm and 159.1±57 nm, respectively. These standard deviations represent a threefold improvement over those of the NMP-exfoliated originals. Phosphorene can also be exfoliated directly in acetone by very long ultrasonication. The product suspension enjoys the same dimensional homogeneity benefits, which confirms that this effect is an intrinsic property of the acetone-BP system. The quality and stability of the exfoliated flakes was checked by XRD, TEM, electron diffraction and Raman spectroscopy. Thermal expansion coefficients of the A1g, B2g and A2g Raman modes were calculated for drop-casted samples as -0.01828 cm-1/K, -0.03056 cm-1/K and -0.03219 cm-1/K, respectively. The flakes withstand 20 minutes in O2 flow at 373 K without lattice distortion. . © 2018 IOP Publishing Ltd.

Rice flakes produced from commercial wild rice: Chemical compositions, vitamin B compounds, mineral and trace element contents and their dietary intake evaluation.

Science.gov (United States)

Sumczynski, Daniela; Koubová, Eva; Šenkárová, Lenka; Orsavová, Jana

2018-10-30

Non-traditional wild rice flakes were analysed for chemical composition, vitamin B compounds, α-tocopherol, mineral and trace elements. Dietary intakes of vitamins, minerals and trace elements were evaluated using FAO/WHO and Institute of Medicine regulations. Wild rice flakes proved to be significant contributors of pyridoxine, pantothenic and folic acids, niacin, thiamine, chromium, magnesium, manganese, phosphorus, zinc, copper, molybdenum and iron to essential dietary intakes values. Toxic dietary intake values for aluminium, cadmium, tin and mercury were less than 33%, which complies the limits for adults set by FAO/WHO for toxic elements intake related to the body weight of 65 kg for females and 80 kg for males taking 100 g of flakes as a portion. However, concentrations of Hg reaching between 3.67 and 12.20 µg/100 g in flakes exceeded the average Hg value of 0.27-1.90 μg/100 g in cereals consumed in the EU. It has to be respected in the future. Copyright © 2018 Elsevier Ltd. All rights reserved.

First-principles study of graphene edge properties and flake shapes

OpenAIRE

Gan, Chee Kwan; Srolovitz, David J.

2009-01-01

We use density functional theory to determine the equilibrium shape of graphene flakes, through the calculation of the edge orientation dependence of the edge energy and edge stress of graphene nanoribbons. The edge energy is a nearly linear function of edge orientation angle; increasing from the armchair orientation to the zigzag orientation. Reconstruction of the zigzag edge lowers its energy to less than that of the armchair edge. The edge stress for all edge orientations is compressive, h...

Popcorn-Derived Porous Carbon Flakes with an Ultrahigh Specific Surface Area for Superior Performance Supercapacitors.

Science.gov (United States)

Hou, Jianhua; Jiang, Kun; Wei, Rui; Tahir, Muhammad; Wu, Xiaoge; Shen, Ming; Wang, Xiaozhi; Cao, Chuanbao

2017-09-13

Popcorn-derived porous carbon flakes have been successfully fabricated from the biomass of maize. Utilizing the "puffing effect", the nubby maize grain turned into materials with an interconnected honeycomb-like porous structure composed of carbon flakes. The following chemical activation method enabled the as-prepared products to possess optimized porous structures for electrochemical energy-storage devices, such as multilayer flake-like structures, ultrahigh specific surface area (S BET : 3301 m 2 g -1 ), and a high content of micropores (microporous surface area of 95%, especially the optimized sub-nanopores with the size of 0.69 nm) that can increase the specific capacitance. The as-obtained sample displayed excellent specific capacitance of 286 F g -1 at 90 A g -1 for supercapacitors. Moreover, the unique porous structure demonstrated an ideal way to improve the volumetric energy density performance. A high energy density of 103 Wh kg -1 or 53 Wh L -1 has been obtained in the case of ionic liquid electrolyte, which is the highest among reported biomass-derived carbon materials and will satisfy the urgent requirements of a primary power source for electric vehicles. This work may prove to be a fast, green, and large-scale synthesis route by using the large nubby granular materials to synthesize applicable porous carbons in energy-storage devices.

Effects of oatmeal and corn flakes cereal breakfasts on satiety, gastric emptying, glucose, and appetite-related hormones.

Science.gov (United States)

Geliebter, Allan; Grillot, Charlotte L; Aviram-Friedman, Roni; Haq, Sakeena; Yahav, Eric; Hashim, Sami A

2015-01-01

The extent to which different types of breakfasts affect appetite and food intake is unclear. To assess the satiety effects of a high-fiber cereal, we compared oatmeal, isocaloric corn flakes, and water. Thirty-six subjects (18 lean, 18 overweight) were assigned to three conditions in a randomized sequence on different days. Ratings of hunger and fullness were obtained concurrently with blood samples for measuring concentrations of glucose, insulin, glucagon, leptin, and acetaminophen (gastric emptying tracer). Appetite was assessed by calculating the area under the curve (AUC) for fullness and hunger, and by measuring food intake of an ad libitum lunch meal at 180 min. Lunch meal intake was lowest after consuming oatmeal (p AUC was greatest (p = 0.00001), and hunger AUC lowest (p blood glucose was lowest after the corn flakes (p = 0.0001). Insulin AUC was greater for both cereals than water (p AUC and glucagon AUC values did not differ between conditions. Acetaminophen concentrations peaked latest after consuming oatmeal (p = 0.046), reflecting slower gastric emptying. Satiety was greater and ad libitum test meal intake lower after consuming oatmeal than after corn flakes, especially in the overweight subjects. © 2015 S. Karger AG, Basel.

New nanocomposite surfaces and thermal interface materials based on mesoscopic microspheres, polymers and graphene flakes

Science.gov (United States)

Dmitriev, Alex A.; Dmitriev, Alex S.; Makarov, Petr; Mikhailova, Inna

2018-04-01

In recent years, there has been a great interest in the development and creation of new functional energy mate-rials, including for improving the energy efficiency of power equipment and for effectively removing heat from energy devices, microelectronics and optoelectronics (power micro electronics, supercapacitors, cooling of processors, servers and data centers). In this paper, the technology of obtaining new nanocomposites based on mesoscopic microspheres, polymers and graphene flakes is considered. The methods of sequential production of functional materials from graphene flakes of different volumetric concentration using epoxy polymers, as well as the addition of monodisperse microspheres are described. Data are given on the measurement of the contact angle and thermal conductivity of these nanocomposites with respect to the creation of thermal interface materials for cooling devices of electronics, optoelectronics and power engineering.

Self-Assembling of Tetradecylammonium Chain on Swelling High Charge Micas (Na-Mica-3 and Na-Mica-2): Effect of Alkylammonium Concentration and Mica Layer Charge.

Science.gov (United States)

Pazos, M Carolina; Cota, Agustín; Osuna, Francisco J; Pavón, Esperanza; Alba, María D

2015-04-21

A family of tetradecylammonium micas is synthesized using synthetic swelling micas with high layer charge (Na(n)Si(8-n)Al(n)Mg6F4O20·XH2O, where n = 2 and 3) exchanged with tetradecylammonium cations. The molecular arrangement of the surfactant is elucidated on the basis of XRD patterns and DTA. The ordering conformation of the surfactant molecules into the interlayer space of micas is investigated by IR/FT, (13)C, (27)Al, and (29)Si MAS NMR. The structural arrangement of the tetradecylammonium cation in the interlayer space of high-charge micas is more sensitive to the effect of the mica layer charge at high concentration. The surfactant arrangement is found to follow the bilayer-paraffin model for all values of layer charge and surfactant concentration. However, at initial concentration below the mica CEC, a lateral monolayer is also observed. The amount of ordered conformation all-trans is directly proportional to the layer charge and surfactant concentration.

Uniform hexagonal graphene flakes and films grown on liquid copper surface

OpenAIRE

Geng, Dechao; Wu, Bin; Guo, Yunlong; Huang, Liping; Xue, Yunzhou; Chen, Jianyi; Yu, Gui; Jiang, Lang; Hu, Wenping; Liu, Yunqi

2012-01-01

Unresolved problems associated with the production of graphene materials include the need for greater control over layer number, crystallinity, size, edge structure and spatial orientation, and a better understanding of the underlying mechanisms. Here we report a chemical vapor deposition approach that allows the direct synthesis of uniform single-layered, large-size (up to 10,000 μm2), spatially self-aligned, and single-crystalline hexagonal graphene flakes (HGFs) and their continuous films ...

Oxidative cleavage and hydrolytic boosting of cellulose in soybean spent flakes by Trichoderma reesei Cel61A lytic polysaccharide monooxygenase.

Science.gov (United States)

Pierce, Brian C; Agger, Jane Wittrup; Wichmann, Jesper; Meyer, Anne S

2017-03-01

The auxiliary activity family 9 (AA9) copper-dependent lytic polysaccharide monooxygenase (LPMO) from Trichoderma reesei (EG4; TrCel61A) was investigated for its ability to oxidize the complex polysaccharides from soybean. The substrate specificity of the enzyme was assessed against a variety of substrates, including both soy spent flake, a by-product of the soy food industry, and soy spent flake pretreated with sodium hydroxide. Products from enzymatic treatments were analyzed using mass spectrometry and high performance anion exchange chromatography. We demonstrate that TrCel61A is capable of oxidizing cellulose from both pretreated soy spent flake and phosphoric acid swollen cellulose, oxidizing at both the C1 and C4 positions. In addition, we show that the oxidative activity of TrCel61A displays a synergistic effect capable of boosting endoglucanase activity, and thereby substrate depolymerization of soy cellulose, by 27%. Copyright © 2016 Elsevier Inc. All rights reserved.

Structural, optical and compositional stability of MoS2 multi-layer flakes under high dose electron beam irradiation

Science.gov (United States)

Rotunno, E.; Fabbri, F.; Cinquanta, E.; Kaplan, D.; Longo, M.; Lazzarini, L.; Molle, A.; Swaminathan, V.; Salviati, G.

2016-06-01

MoS2 multi-layer flakes, exfoliated from geological molybdenite, have been exposed to high dose electron irradiation showing clear evidence of crystal lattice and stoichiometry modifications. A massive surface sulfur depletion is induced together with the consequent formation of molybdenum nanoislands. It is found that a nanometric amorphous carbon layer, unwillingly deposited during the transmission electron microscope experiments, prevents the formation of the nanoislands. In the absence of the carbon layer, the formation of molybdenum grains proceeds both on the top and bottom surfaces of the flake. If carbon is present on both the surfaces then the formation of Mo grains is completely prevented.

Synthesis and room temperature photoluminescence of ZnO/CTAB ordered layered nanocomposite with flake-like architecture

International Nuclear Information System (INIS)

Wang, Y.D.; Zhang, S.; Ma, C.L.; Li, H.D.

2007-01-01

Flake-like ZnO/surfactant ordered layered nanocomposite has been synthesized by self-assembly at room temperature with the presence of cetyltrimethylammonium bromide (CTAB, CH 3 (CH 2 ) 15 N + (CH 3 ) 3 Br - ) surfactant. The procedure described in this study is attractive since it gives high yields of ordered layered nanocomposite with flake-like architecture. XRD results showed the formation of a layered structure with two layered spacings ca. 18.56 A. SEM and FT-IR spectroscopy were used to further characterize ZnO/CTAB nanolayered composite. The ZnO/CTAB-ordered layered nanocomposite exhibits the room temperature photoluminescence (RTPL) characteristics. It is inferred that the RTPL of ZnO/CTAB-layered nanocomposite might be induced by the interfacial effect between the ZnO and the surfactant

Electrodeposition of flake-like Cu_2O on vertically aligned two-dimensional TiO_2 nanosheet array films for enhanced photoelectrochemical properties

International Nuclear Information System (INIS)

Yang, Lei; Zhang, Miao; Zhu, Kerong; Lv, Jianguo; He, Gang; Sun, Zhaoqi

2017-01-01

Highlights: • Flake-like Cu_2O/TNS with exposed {001} facets constructed p-n heterostructure. • The TNS arrays were used as starting substrates for Cu_2O growth. • The Cu_2O/TNS prepared at −0.4 V exhibits the best photoelectrochemical property. - Abstract: A novel Cu_2O/TNS composite structure of single crystal TiO_2 nanosheet (TNS) arrays decorated with flake-like Cu_2O were synthesized by a facile hydrothermal reaction followed by the electrodeposition process. The effects of deposition potential on the microstructure, morphology, and optical property of the thin films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–vis spectrophotometer. When the deposition potential is higher than −0.4 V, peaks corresponding to Cu appear, meanwhile, flake-like Cu_2O become agglomerating, and transform into dense Cu_2O particles. Additionally, photoelectrochemical experiments indicate that the films deposited at −0.4 V show the lowest resistivity and highest exciton separation efficiency. This enhanced photoelectrochemical properties can be explained by synergistic effect of p-type flake-like Cu_2O and n-type TiO_2 heterojunctions combined with two-dimensional TiO_2 nanosheet with exposed highly reactive {001} facets.

Using vibrational molecular spectroscopy to reveal association of steam-flaking induced carbohydrates molecular structural changes with grain fractionation, biodigestion and biodegradation

Science.gov (United States)

Xu, Ningning; Liu, Jianxin; Yu, Peiqiang

2018-04-01

Advanced vibrational molecular spectroscopy has been developed as a rapid and non-destructive tool to reveal intrinsic molecular structure conformation of biological tissues. However, this technique has not been used to systematically study flaking induced structure changes at a molecular level. The objective of this study was to use vibrational molecular spectroscopy to reveal association between steam flaking induced CHO molecular structural changes in relation to grain CHO fractionation, predicted CHO biodegradation and biodigestion in ruminant system. The Attenuate Total Reflectance Fourier-transform Vibrational Molecular Spectroscopy (ATR-Ft/VMS) at SRP Key Lab of Molecular Structure and Molecular Nutrition, Ministry of Agriculture Strategic Research Chair Program (SRP, University of Saskatchewan) was applied in this study. The fractionation, predicted biodegradation and biodigestion were evaluated using the Cornell Net Carbohydrate Protein System. The results show that: (1) The steam flaking induced significant changes in CHO subfractions, CHO biodegradation and biodigestion in ruminant system. There were significant differences between non-processed (raw) and steam flaked grain corn (P R2 = 0.87, RSD = 0.74, P R2 = 0.87, RSD = 0.24, P < .01). In summary, the processing induced molecular CHO structure changes in grain corn could be revealed by the ATR-Ft/VMS vibrational molecular spectroscopy. These molecular structure changes in grain were potentially associated with CHO biodegradation and biodigestion.

Electronic properties of graphene nano-flakes: Energy gap, permanent dipole, termination effect and Raman spectroscopy

OpenAIRE

Singh, Sandeep Kumar; Neek-Amal, M.; Peeters, F. M.

2014-01-01

The electronic properties of graphene nano-flakes (GNFs) with different edge passivation is investigated by using density functional theory. Passivation with F and H atoms are considered: C$_{N_c}$ X$_{N_x}$ (X=F or H). We studied GNFs with $10

Investigation of corrosion behavior of aluminum flakes coated by polymeric nanolayer: Effect of polymer type

International Nuclear Information System (INIS)

Amirshaqaqi, Naghmeh; Salami-Kalajahi, Mehdi; Mahdavian, Mohammad

2014-01-01

Highlights: • Protection of aluminum pigments from corrosion phenomenon by an encapsulating polystyrene and poly(acrylic acid) nanolayers. • Chemical stability of the aluminum pigments in alkaline and acidic aqueous media was examined. • Polystyrene coating remarkably improved flakes’ anticorrosion property while PAA evolved hydrogen. - Abstract: Protection of aluminum pigments from corrosion phenomenon has been extended by an encapsulating polystyrene (PS) and poly(acrylic acid) (PAA) nanolayers. Flakes were first coupled with 3-methacryloxypropyltrimethoxysilane (MPS) and in situ polymerizations of styrene and acrylic acid, initiating with Azobisisobutyronitrile (AIBN) were performed. The encapsulated flakes were characterized by Fourier transform infrared (FTIR), energy-dispersive X-ray spectroscopy (EDX), and transmission electron microscope (TEM). Also, polymer chains were analyzed by gel permeation chromatography (GPC). Subsequently the chemical stability of the pigments in alkaline and acidic aqueous media was examined. Results indicated that polystyrene coating remarkably improved flakes’ anticorrosion property while PAA evolved hydrogen

A comparative study on the activity of fungal lytic polysaccharide monooxygenases for the depolymerization of cellulose in soybean spent flakes.

Science.gov (United States)

Pierce, Brian C; Agger, Jane Wittrup; Zhang, Zhenghong; Wichmann, Jesper; Meyer, Anne S

2017-09-08

Lytic polysaccharide monooxygenases (LPMOs) are copper-dependent enzymes capable of the oxidative breakdown of polysaccharides. They are of industrial interest due to their ability to enhance the enzymatic depolymerization of recalcitrant substrates by glycoside hydrolases. In this paper, twenty-four lytic polysaccharide monooxygenases (LPMOs) expressed in Trichoderma reesei were evaluated for their ability to oxidize the complex polysaccharides in soybean spent flakes, an abundant and industrially relevant substrate. TrCel61A, a soy-polysaccharide-active AA9 LPMO from T. reesei, was used as a benchmark in this evaluation. In total, seven LPMOs demonstrated activity on pretreated soy spent flakes, with the products from enzymatic treatments evaluated using mass spectrometry and high performance anion exchange chromatography. The hydrolytic boosting effect of the top-performing enzymes was evaluated in combination with endoglucanase and beta-glucosidase. Two enzymes (TrCel61A and Aspte6) showed the ability to release more than 36% of the pretreated soy spent flake glucose - a greater than 75% increase over the same treatment without LPMO addition. Copyright © 2017 Elsevier Ltd. All rights reserved.

Detection of fatigue fracture in pearlitic flake graphite cast iron with the help of scanning and transmission electron microscopy

International Nuclear Information System (INIS)

Dunger, B.; Hunger, J.

1976-01-01

To prove the existence of the characteristic features of fatigue fracture in a pearlitic flake graphite cast iron, its fracture surface topography revealed by scanning electron microscopy has been compared with that of a pearlitic steel, the fractures having been caused by static tensile and by cyclic bending tests. The characteristic features of fatigue fracture were visible in the pearlitic matrix of the steel and of the flake graphite cast iron as well. These features differ characteristically from the lamellar structure of the pearlite, particularly after etching the surface area of the fractures. The graphite structures as viewed on the electron scanning and the electron transmission microscope are described. (orig.) [de

Out-of-plane Piezoelectricity and Ferroelectricity in Layered α-In2Se3 Nano-flakes

KAUST Repository

Zhou, Yu

2017-08-25

Piezoelectric and ferroelectric properties in the two dimensional (2D) limit are highly desired for nanoelectronic, electromechanical, and optoelectronic applications. Here we report the first experimental evidence of out-of-plane piezoelectricity and ferroelectricity in van der Waals layered α-In2Se3 nano-flakes. The non-centrosymmetric R3m symmetry of the α-In2Se3 samples is confirmed by scanning transmission electron microscopy, second-harmonic generation, and Raman spectroscopy measurements. Domains with opposite polarizations are visualized by piezo-response force microscopy. Single-point poling experiments suggest that the polarization is potentially switchable for α-In2Se3 nano-flakes with thicknesses down to ~ 10 nm. The piezotronic effect is demonstrated in two-terminal devices, where the Schottky barrier can be modulated by the strain-induced piezopotential. Our work on polar α-In2Se3, one of the model 2D piezoelectrics and ferroelectrics with simple crystal structures, shows its great potential in electronic and photonic applications.

Out-of-plane Piezoelectricity and Ferroelectricity in Layered α-In2Se3 Nano-flakes

KAUST Repository

Zhou, Yu; Wu, Di; Zhu, Yihan; Cho, Yujin; He, Qing; Yang, Xiao; Herrera, Kevin; Chu, Zhaodong; Han, Yu; Downer, Mike; Peng, Hailin; Lai, Keji

2017-01-01

Piezoelectric and ferroelectric properties in the two dimensional (2D) limit are highly desired for nanoelectronic, electromechanical, and optoelectronic applications. Here we report the first experimental evidence of out-of-plane piezoelectricity and ferroelectricity in van der Waals layered α-In2Se3 nano-flakes. The non-centrosymmetric R3m symmetry of the α-In2Se3 samples is confirmed by scanning transmission electron microscopy, second-harmonic generation, and Raman spectroscopy measurements. Domains with opposite polarizations are visualized by piezo-response force microscopy. Single-point poling experiments suggest that the polarization is potentially switchable for α-In2Se3 nano-flakes with thicknesses down to ~ 10 nm. The piezotronic effect is demonstrated in two-terminal devices, where the Schottky barrier can be modulated by the strain-induced piezopotential. Our work on polar α-In2Se3, one of the model 2D piezoelectrics and ferroelectrics with simple crystal structures, shows its great potential in electronic and photonic applications.

Carbon nanofibers wrapped with zinc oxide nano-flakes as promising electrode material for supercapacitors.

Science.gov (United States)

Pant, Bishweshwar; Park, Mira; Ojha, Gunendra Prasad; Park, Juhyeong; Kuk, Yun-Su; Lee, Eun-Jung; Kim, Hak-Yong; Park, Soo-Jin

2018-07-15

A combination of electrospinning technique and hydrothermal process was carried out to fabricate zinc oxide nano-flakes wrapped carbon nanofibers (ZnO/CNFs) composite as an effective electrode material for supercapacitor. The morphology of the as-synthesized composite clearly revealed that the carbon nanofibers were successfully wrapped with ZnO nano-flakes. The electrochemical performance of the as-synthesized nanocomposite electrode was evaluated by the cyclic voltammetry (CV), galvanostatic charge-discharge (GDC), and electrochemical impedance spectroscopy (EIS), and compared with the pristine ZnO nanofibers. It was found that the composite exhibited a higher specific capacitance (260 F/g) as compared to pristine ZnO NFs (118 F/g) at the scan rate of 5 mV/s. Furthermore, the ZnO/CNFs composite also exhibited good capacity retention (73.33%). The obtained results indicated great potential applications of ZnO/CNFs composite in developing energy storage devices with high energy and power densities. The present work might provide a new route for utilizing ZnO based composites for energy storage applications. Copyright © 2018 Elsevier Inc. All rights reserved.

Functional energy nanocomposites surfaces based on mesoscopic microspheres, polymers and graphene flakes

Science.gov (United States)

Alekseev, S. A.; Dmitriev, A. S.; Dmitriev, A. A.; Makarov, P. G.; Mikhailova, I. A.

2017-11-01

In recent years, there has been a great interest in the development and creation of new functional energy materials, including for improving the energy efficiency of power equipment and for effectively removing heat from energy devices, microelectronics and optoelectronics (power micro electronics, supercapacitors, cooling of processors, servers and Data centers). In this paper, the technology of obtaining a new nanocomposite based on mesoscopic microspheres, polymers and graphene flakes is considered. The methods of sequential production of functional materials from graphite flakes of different volumetric concentration using polymers based on epoxy resins and polyimide, as well as the addition of a mesoscopic medium in the form of monodisperse microspheres are described. The data of optical and electron microscopy of such nanocomposites are presented, the main problems in the appearance of defects in such materials are described, the possibilities of their elimination by the selection of different concentrations and sizes of the components. Data are given on the measurement of the hysteresis of the contact angle and the evaporation of droplets on similar substrates. The results of studying the mechanical, electrophysical and thermal properties of such nanocomposites are presented. Particular attention is paid to the investigation of the thermal conductivity of these nanocomposites with respect to the creation of thermal interface materials for cooling devices of electronics, optoelectronics and power engineering.

Determine Minimum Silver Flake Addition to GCM for Iodine Loaded AgZ

Energy Technology Data Exchange (ETDEWEB)

Garino, Terry J.; Nenoff, Tina M.; Rodriguez, Mark A.

2014-04-01

The minimum amount of silver flake required to prevent loss of I{sub 2} during sintering in air for a SNL Glass Composite Material (GCM) Waste Form containing AgI-MOR (ORNL, 8.7 wt%) was determined to be 1.1 wt% Ag. The final GCM composition prior to sintering was 20 wt% AgI-MOR, 1.1 wt% Ag, and 80 wt% Bi-Si oxide glass. The amount of silver flake needed to suppress iodine loss was determined using thermo gravimetric analysis with mass spectroscopic off-gas analysis. These studies found that the ratio of silver to AgI-MOR required is lower in the presence of the glass than without it. Therefore an additional benefit of the GCM is that it serves to inhibit some iodine loss during processing. Alternatively, heating the AgI-MOR in inert atmosphere instead of air allowed for densified GCM formation without I{sub 2} loss, and no necessity for the addition of Ag. The cause of this behavior is found to be related to the oxidation of the metallic Ag to Ag{sup +} when heated to above ~300{degrees}C in air. Heating rate, iodine loading levels and atmosphere are the important variables that determine AgI migration and results suggest that AgI may be completely incorporated into the mordenite structure by the 550{degrees}C sintering temperature.

Magnetoresistance and Hall resistivity of semimetal WTe2 ultrathin flakes.

Science.gov (United States)

Luo, Xin; Fang, Chi; Wan, Caihua; Cai, Jialin; Liu, Yong; Han, Xiufeng; Lu, Zhihong; Shi, Wenhua; Xiong, Rui; Zeng, Zhongming

2017-04-07

This article reports the characterization of WTe 2 thin flake magnetoresistance and Hall resistivity. We found it does not exhibit magnetoresistance saturation when subject to high fields, in a manner similar to their bulk characteristics. The linearity of Hall resistivity in our devices confirms the compensation of electrons and holes. By relating experimental results to a classic two-band model, the lower magnetoresistance values in our samples is demonstrated to be caused by decreased carrier mobility. The dependence of mobility on temperature indicates the main role of optical phonon scattering at high temperatures. Our results provide more detailed information on carrier behavior and scattering mechanisms in WTe 2 thin films.

Bioremediation of crude oil polluted seawater by a hydrocarbon-degrading bacterial strain immobilized on chitin and chitosan flakes

International Nuclear Information System (INIS)

Gentili, A.R.; Cubitto, M.A.; Ferrero, M.; Rodriguez, M.S.

2006-01-01

In this laboratory-scale study, we examined the potential of chitin and chitosan flakes obtained from shrimp wastes as carrier material for a hydrocarbon-degrading bacterial strain. Flakes decontamination, immobilization conditions and the survival of the immobilized bacterial strain under different storage temperatures were evaluated. The potential of immobilized hydrocarbon-degrading bacterial strain for crude oil polluted seawater bioremediation was tested in seawater microcosms. In terms of removal percentage of crude oil after 15 days, the microcosms treated with the immobilized inoculants proved to be the most successful. The inoculants formulated with chitin and chitosan as carrier materials improved the survival and the activity of the immobilized strain. It is important to emphasize that the inoculants formulated with chitin showed the best performance during storage and seawater bioremediation. (author)

Electronic properties of graphene nano-flakes: energy gap, permanent dipole, termination effect, and Raman spectroscopy.

Science.gov (United States)

Singh, Sandeep Kumar; Neek-Amal, M; Peeters, F M

2014-02-21

The electronic properties of graphene nano-flakes (GNFs) with different edge passivation are investigated by using density functional theory. Passivation with F and H atoms is considered: C(N(c)) X(N(x)) (X = F or H). We studied GNFs with 10 GNFs and enhance the electric polarization, (iii) the mutual interaction of bilayer GNFs can be understood by dipole-dipole interaction which were found sensitive to the relative orientation of the GNFs, (iv) the permanent dipoles depend on the edge terminated atom, while the energy gap is independent of it, and (v) the presence of heptagon and pentagon defects in the GNFs results in the largest difference between the energy of the spin-up and spin-down electrons which is larger for the H-passivated GNFs as compared to F-passivated GNFs. Our study shows clearly the effect of geometry, size, termination, and bilayer on the electronic properties of small GNFs. This study reveals important features of graphene nano-flakes which can be detected using Raman spectroscopy.

Milk production, nutrient digestibility and nitrogen balance in lactating cows fed total mixed ration silages containing steam-flaked brown rice as substitute for steam-flaked corn, and wet food by-products.

Science.gov (United States)

Miyaji, Makoto; Matsuyama, Hiroki; Hosoda, Kenji; Nonaka, Kazuhisa

2013-06-01

The objective of this study was to evaluate the effect of substituting brown rice grain for corn grain in total mixed ration (TMR) silage containing food by-products on the milk production, whole-tract nutrient digestibility and nitrogen balance in dairy cows. Six multiparous Holstein cows were used in a crossover design with two dietary treatments: a diet containing 30.9% steam-flaked corn (corn TMR) or 30.9% steam-flaked brown rice (rice TMR) with wet soybean curd residue and wet soy sauce cake. Dietary treatment did not affect the dry matter intake, milk yield and compositions in dairy cows. The dry matter and starch digestibility were higher, and the neutral detergent fiber digestibility was lower for rice TMR than for corn TMR. The urinary nitrogen (N) excretion as a proportion of the N intake was lower for rice TMR than for corn TMR with no dietary effect on N secretion in milk and fecal N excretion. These results indicated that the replacement of corn with brown rice in TMR silage relatively reduced urinary N loss without adverse effects on feed intake and milk production, when food by-products such as soybean curd residue were included in the TMR silage as dietary crude protein sources. © 2013 Japanese Society of Animal Science.

Mica fission detectors

International Nuclear Information System (INIS)

Wong, C.; Anderson, J.D.; Hansen, L.; Lehn, A.V.; Williamson, M.A.

1977-01-01

The present development status of the mica fission detectors is summarized. It is concluded that the techniques have been refined and developed to a state such that the mica fission counters are a reliable and reproducible detector for fission events

Electrodeposition of flake-like Cu{sub 2}O on vertically aligned two-dimensional TiO{sub 2} nanosheet array films for enhanced photoelectrochemical properties

Energy Technology Data Exchange (ETDEWEB)

Yang, Lei [School of Physics & Material Science, Anhui University, Hefei 230601 (China); Co-operative Innovation Research Center for Weak Signal-Detecting Materials and Devices Integration, Anhui University, Hefei 230601 (China); Institute of Applied Physics AOA, Hefei 230031 (China); Zhang, Miao; Zhu, Kerong [School of Physics & Material Science, Anhui University, Hefei 230601 (China); Lv, Jianguo [School of Electronic & Information Engineering, Hefei Normal University, Hefei 230601 (China); He, Gang [School of Physics & Material Science, Anhui University, Hefei 230601 (China); Sun, Zhaoqi, E-mail: szq@ahu.edu.cn [School of Physics & Material Science, Anhui University, Hefei 230601 (China)

2017-01-01

Highlights: • Flake-like Cu{sub 2}O/TNS with exposed {001} facets constructed p-n heterostructure. • The TNS arrays were used as starting substrates for Cu{sub 2}O growth. • The Cu{sub 2}O/TNS prepared at −0.4 V exhibits the best photoelectrochemical property. - Abstract: A novel Cu{sub 2}O/TNS composite structure of single crystal TiO{sub 2} nanosheet (TNS) arrays decorated with flake-like Cu{sub 2}O were synthesized by a facile hydrothermal reaction followed by the electrodeposition process. The effects of deposition potential on the microstructure, morphology, and optical property of the thin films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–vis spectrophotometer. When the deposition potential is higher than −0.4 V, peaks corresponding to Cu appear, meanwhile, flake-like Cu{sub 2}O become agglomerating, and transform into dense Cu{sub 2}O particles. Additionally, photoelectrochemical experiments indicate that the films deposited at −0.4 V show the lowest resistivity and highest exciton separation efficiency. This enhanced photoelectrochemical properties can be explained by synergistic effect of p-type flake-like Cu{sub 2}O and n-type TiO{sub 2} heterojunctions combined with two-dimensional TiO{sub 2} nanosheet with exposed highly reactive {001} facets.

Biotermodin?mica en animales

OpenAIRE

Granados Moreno, Jairo Enrique

2014-01-01

El documento presenta como la termodin?mica es la ciencia que estudia las relaciones entre calor y las dem?s formas de transferencias de energ?a. Se explica que toda transformaci?n biofisicoqu?mica implica, generalmente, un cambio energ?tico. Se tratan los conceptos de temperatura, escalas de temperatura, calor, calor de combusti?n, postulados de la termodin?mica, entrop?a y energ?a libre metab?lica

Graphene: powder, flakes, ribbons, and sheets.

Science.gov (United States)

James, Dustin K; Tour, James M

2013-10-15

Graphene's unique physical and electrical properties (high tensile strength, Young's modulus, electron mobility, and thermal conductivity) have led to its nickname of "super carbon." Graphene research involves the study of several different physical forms of the material: powders, flakes, ribbons, and sheets and others not yet named or imagined. Within those forms, graphene can include a single layer, two layers, or ≤10 sheets of sp² carbon atoms. The chemistry and applications available with graphene depend on both the physical form of the graphene and the number of layers in the material. Therefore the available permutations of graphene are numerous, and we will discuss a subset of this work, covering some of our research on the synthesis and use of many of the different physical and layered forms of graphene. Initially, we worked with commercially available graphite, with which we extended diazonium chemistry developed to functionalize single-walled carbon nanotubes to produce graphitic materials. These structures were soluble in common organic solvents and were better dispersed in composites. We developed an improved synthesis of graphene oxide (GO) and explored how the workup protocol for the synthesis of GO can change the electronic structure and chemical functionality of the GO product. We also developed a method to remove graphene layers one-by-one from flakes. These powders and sheets of GO can serve as fluid loss prevention additives in drilling fluids for the oil industry. Graphene nanoribbons (GNRs) combine small width with long length, producing valuable electronic and physical properties. We developed two complementary syntheses of GNRs from multiwalled carbon nanotubes: one simple oxidative method that produces GNRs with some defects and one reductive method that produces GNRs that are less defective and more electrically conductive. These GNRs can be used in low-loss, high permittivity composites, as conductive reinforcement coatings on Kevlar

Intrinsic evolution of novel (Nd, MM)2Fe14B-system magnetic flakes

Science.gov (United States)

Yu, Xiaoqiang; Zhu, Minggang; Liu, Weiqiang; Li, Yanfeng; Zhang, Jiuxing; Yue, Ming; Li, Wei

2018-01-01

The Nd-substituted (Nd x MM1- x )-Fe-B strip-casting flakes were prepared by induction melting in the vacuum furnace and then subsequently by strip-casting technology. The microstructure and magnetic properties of (Nd x MM1- x )-Fe-B alloys are related to the Nd substitution. 2:14:1 main phases and minor impure phases coexist in the MM-Fe-B flake. For example, La2O3 and CeFe2 impure phases are obviously detected in the x = 0 specimen. As an increase of the Ce concentration is inversely accompanied with the decrease of the Nd content ( x) in (Nd x MM1- x )2Fe14B main phases (0 ≤ x ≤ 1), XRD analysis shows that the overall diffraction peaks of the main phases shift to right domestically because of smaller radius Ce4+. The melting point, spin reorientation phase transition temperature, Curie temperature, magneto-crystalline anisotropy field (at 300 K), and the magnetization ( M 9T) for MM-Fe-B/(Nd0.4MM0.6)-Fe-B/(Nd0.7MM0.3)-Fe-B/Nd-Fe-B strip-casting alloys are 1376.15/1414.15/1439.15/1458.15 K, 74/113/124/135 K, 493.2/538.4/559.7/582.3 K, 48/55.2/64.4/70.1 kOe and 136.5/143.7/151.5/153.7 emu/g, respectively. Due to the varied composition of hard magnetic main phases, M 9T increases gradually with the increase of Nd content ( x). SEM observation and EDX results demonstrate that more Nd and Pr elements aggregate into the 2:14:1 ferromagnetic phase, while less La and Ce elements are prone to the RE-rich region compared with the nominal ratio. As a result, the growth of M 9T becomes extraordinary under maximum external field 9 T, indicating that the (Nd0.7MM0.3)-Fe-B flake may display relatively good magnetic properties and those with higher Nd content have evident effect on magnetization, compositions, and microstructures of hard magnetic main phases. Therefore, practical application of (Nd x MM1- x )-Fe-B-sintered magnets will be very prospective.

Creating high yield water soluble luminescent graphene quantum dots via exfoliating and disintegrating carbon nanotubes and graphite flakes.

Science.gov (United States)

Lin, Liangxu; Zhang, Shaowei

2012-10-21

We have developed an effective method to exfoliate and disintegrate multi-walled carbon nanotubes and graphite flakes. With this technique, high yield production of luminescent graphene quantum dots with high quantum yield and low oxidization can be achieved.

Nickel oxide crystalline nano flakes: synthesis, characterization and their use as anode in lithium-ion batteries

DEFF Research Database (Denmark)

Ahmadi, Majid; Younesi, Reza; Vegge, Tejs

2014-01-01

Nickel oxide crystalline nano flakes (NONFs)—only about 10 nm wide—were produced using a simple and inexpensive chemistry method followed by a short annealing in ambient air. In a first step, Ni(OH)2 sheets were synthesized by adding sodium hydroxide (NaOH) drop-wise in a Ni(NO3)2 aqueous solutio...

A comparative study on the activity of fungal lytic polysaccharide monooxygenases for the depolymerization of cellulose in soybean spent flakes

DEFF Research Database (Denmark)

Pierce, Brian; Wittrup Agger, Jane; Zhang, Zhenghong

2017-01-01

Lytic polysaccharide monooxygenases (LPMOs) are copper-dependent enzymes capable of the oxidative breakdown of polysaccharides. They are of industrial interest due to their ability to enhance the enzymatic depolymerization of recalcitrant substrates by glycoside hydrolases. In this paper, twenty......-four lytic polysaccharide monooxygenases (LPMOs) expressed in Trichoderma reesei were evaluated for their ability to oxidize the complex polysaccharides in soybean spent flakes, an abundant and industrially relevant substrate. TrCel61A, a soy-polysaccharide-active AA9 LPMO from T. reesei, was used...... as a benchmark in this evaluation. In total, seven LPMOs demonstrated activity on pretreated soy spent flakes, with the products from enzymatic treatments evaluated using mass spectrometry and high performance anion exchange chromatography. The hydrolytic boosting effect of the top-performing enzymes...

Microwave properties of sphere-, flake-, and disc-shaped BaFe12O19 nanoparticle inks for high-frequency applications on printed electronics

International Nuclear Information System (INIS)

Myllymäki, S.; Maček Kržmanc, M.; Sloma, M.; Juuti, J.; Nelo, M.; Teirikangas, M.; Jakubowska, M.; Suvorov, D.; Jantunen, H.

2016-01-01

Spherical (diameter 50–200 nm), flake- (diameter 40–200 nm), and disc-shaped (diameter 10–20 nm) BaFe 12 O 19 nanoparticles were synthesized with a wet chemical method, and their permittivity, electric loss tangent, permeability, and magnetic loss tangent were measured in the 0.045–10 GHz range. The materials were prepared using a solution of 12% PMMA resin in a butyldiglycol solvent for 10–50 wt% filling content. Microstrip transmission-line perturbation was used to measure complex permeability and the split post dielectric resonator method was employed to measure dielectric properties. The frequency dependence of the permeability and permittivity spectra of the composites was affected by their shape and filling fraction. The composites made with spherical particles had higher permeability values (1.4–1.75) at 1 GHz than the composites made with flake (1.25–1.6) or disc particles (1.1–1.3), but the spherical particles caused more losses. The flake particle composite provided permeability and magnetic loss characteristics at both 1 GHz and 7 GHz superior to those of the sphere particle composite in low-loss RF applications. The magnetic loss tangent of PMMA/BaFe 12 O 19 was 0.2–0.3 at 1 GHz, being lower than that of state-of-the-art PANI/BaFe 12 O 19 composites. The sphere composite inks showed permeability values less than 1 at 1–4 GHz ferromagnetic resonance (FMR); they could be used as a tunable material in microwave applications. The sphere and flake composite inks also had sufficient printing quality for the screen-printing fabrication method.

Pretreatment of cottonseed flakes with proteases and an amylase for higher oil yields

Directory of Open Access Journals (Sweden)

Hassanein, Minar M.

2007-09-01

Full Text Available The effect of enzymatic pretreatment of cottonseed flakes on oil extractability was studied. The enzymes investigated included bacterial protease (Bp, papain (Pa, savinase (S, termamyl (T, pectinase (Pe and cellulase (C. The variables studied during the enzymatic hydrolysis experiments were: enzyme concentration, moisture: cottonseed flakes ratio, and time of hydrolysis. Enzymatic hydrolysis experiments were first carried out with a single enzyme, then with enzyme mixtures formulated according to the results of single enzyme treatments. Results were evaluated based on the relative increase in oil extractability, and some oil characteristics in comparison with untreated cottonseed flakes (control. Pretreatment with enzyme mixtures resulted in a relative increase in oil extractability that was higher than single enzyme pretreatment and the control. Statistical analysis showed a significant difference (at 5% level between the control and all enzymatically treated oils as well as among different enzymatically treated oils. The relative increase in oil extractability due to pretreatment with enzyme mixtures were in the following order: S: Pe: Bp>S: P>S: C: Pe>S: Bp>S:T>S: C >S: Pa with values 44.9%, 38.9%, 37.1%, 34.9%, 30.1%, 28.9%, respectively. Enzymatic pretreatment of cottonseed flakes resulted in oils with fatty acid composition, acid value, iodine value and peroxide values that were generally comparable to the control.En este trabajo se estudió el efecto del pretratamiento con enzimas sobre la extractabilidad del aceite en hojuelas de semilla de algodón. Las enzimas que se investigaron fueron proteasa bacteriana (Bp, papaína (Pa, savinasa (S, temamil (T, pectinasa (Pe y celulasa (C. Las variables estudiadas durante los experimentos de hidrólisis enzimática fueron: concentración de la enzima, ratio humedad:cantidad de hojuelas y tiempo de hidrólisis. Estos experimentos se realizaron primeramente con una sola enzima y posteriormente con

Shaping-lathe headrig will convert small hardwoods into pallet cants plus flakes for structural exterior flakeboard

Science.gov (United States)

Peter Koch

1975-01-01

Virtually all nations have an under-utilized resource of small-diameter, low-grade hardwoods of mixed species in a range of densities. The shaping-lathe headrig, now in the final stages of commercialization, is a key to utilizing these hardwoods for pallets, industrial lumber, and-with further development-railroad crossties. Lathe residues in the form of flakes can be...

Facile Synthesis of Nitrogen Doped Graphene Oxide from Graphite Flakes and Powders: A Comparison of Their Surface Chemistry.

Science.gov (United States)

Yokwana, Kholiswa; Ray, Sekhar C; Khenfouch, Mohammad; Kuvarega, Alex T; Mamba, Bhekie B; Mhlanga, Sabelo D; Nxumalo, Edward N

2018-08-01

Nitrogen-doped graphene oxide (NGO) nanosheets were prepared via a facile one-pot modified Hummer's approach at low temperatures using graphite powder and flakes as starting materials in the presence of a nitrogen precursor. It was found that the morphology, structure, composition and surface chemistry of the NGO nanosheets depended on the nature of the graphite precursor used. GO nanosheets doped with nitrogen atoms exhibited a unique structure with few thin layers and wrinkled sheets, high porosity and structural defects. NGO sheets made from graphite powder (NGOp) exhibited excellent thermal stability and remarkably high surface area (up to 240.53 m2 ·g-1) compared to NGO sheets made from graphite flakes (NGOf) which degraded at low temperatures and had an average surface area of 24.70 m2 ·g-1. NGOf sheets had a size range of 850 to 2200 nm while NGOp sheets demonstrated obviously small sizes (460-1600 nm) even when exposed to different pH conditions. The NGO nanosheets exhibited negatively charged surfaces in a wide pH range (1 to 12) and were found to be stable above pH 6. In addition, graphite flakes were found to be more suitable for the production of NGO as they produced high N-doping levels (0.65 to 1.29 at.%) compared to graphite powders (0.30 to 0.35 at.%). This study further demonstrates that by adjusting the amount of N source in the host GO, one can tailor its thermal stability, surface morphology, surface chemistry and surface area.

Surface-modified microelectrode array with flake nanostructure for neural recording and stimulation

Energy Technology Data Exchange (ETDEWEB)

Kim, Ju-Hyun; Choi, Yang-Kyu [Nano-Oriented Bio-Electronics Lab, Department of Electrical Engineering, College of Information Science and Technology, KAIST, Daejeon 305-701 (Korea, Republic of); Kang, Gyumin; Nam, Yoonkey, E-mail: ynam@kaist.ac.kr, E-mail: ykchoi@ee.kaist.ac.kr [Department of Bio and Brain Engineering, KAIST, KAIST Institute for Nano-Century, Daejeon 305-701 (Korea, Republic of)

2010-02-26

A novel microelectrode modification method is reported for neural electrode engineering with a flake nanostructure (nanoflake). The nanoflake-modified electrodes are fabricated by combining conventional lithography and electrochemical deposition to implement a microelectrode array (MEA) on a glass substrate. The unique geometrical properties of nanoflake sharp tips and valleys are studied by optical, electrochemical and electrical methods in order to verify the advantages of using nanoflakes for neural recording devices. The in vitro recording and stimulation of cultured hippocampal neurons are demonstrated on the nanoflake-modified MEA and the clear action potentials are observed due to the nanoflake impedance reduction effect.

Rapid identification of graphene flakes: alumina does it better

International Nuclear Information System (INIS)

De Marco, P; Nardone, M; Santucci, S; Ottaviano, L; Del Vitto, A; Alessandri, M

2010-01-01

We report a systematic investigation of the colour contrast (CC) of graphene (one, two and three layers) on 50, 72 and 80 nm thick Al 2 O 3 /Si(100) and 100 and 300 nm thick SiO 2 /Si(100). The CC is determined by the analysis of optical microscopy images taken under white light illumination. A corresponding assignment of graphene in the single-layer, double-layer and trilayer phases is made using micro-Raman spectroscopy. A quantitative evaluation allows us to conclude that the colour contrast between 72 nm alumina and graphene is significantly larger than that between 300 nm silicon oxide and graphene (by factors of 2.2, 2.0 and 3.3 for the single-layer, double-layer and trilayer graphene flakes respectively). Moreover, data indicate that, to increase visibility, the use of a red or a green light is preferable.

Chemical synthesis of spinel cobalt ferrite (CoFe2O4) nano-flakes for supercapacitor application

International Nuclear Information System (INIS)

Kumbhar, V.S.; Jagadale, A.D.; Shinde, N.M.; Lokhande, C.D.

2012-01-01

Highlights: ► The first time preparation of cobalt ferrite material in thin film form, using chemical method at low temperature. ► A nano-flake like morphology of the cobalt ferrite thin film. ► An application of the film as an electrode in supercapacitor cell. - Abstract: The present paper reveals the formation of cobalt ferrite (CoFe 2 O 4 ) thin film on stainless steel substrate by simple chemical route from an alkaline bath containing Co 2+ and Fe 2+ ions. The films are characterised for structural, surface morphological and FT-IR properties. The XRD and FT-IR studies revealed formation of single phase of CoFe 2 O 4 . The formation of nano-flakes-like morphology is observed from scanning electron microscope. The electrochemical behaviour of CoFe 2 O 4 film has been studied using cyclic voltammetry in 1 M NaOH electrolyte. The maximum specific capacitance of 366 F g −1 is obtained at the scan rate of 5 mV s −1 . Using AC impedance technique equivalent series resistance (ESR) value is found to be 1.1 Ω.

Effect of cathode vibration and heat treatment on electromagnetic properties of flake-shaped diatomite coated with Ni–Fe alloy by electroplating

Energy Technology Data Exchange (ETDEWEB)

Lan, Mingming, E-mail: lan_mingming@163.com; Li, Huiqin; Huang, Weihua; Xu, Guangyin; Li, Yan

2015-03-01

In this paper, flake-shaped diatomite particles were used as forming templates for the fabrication of the ferromagnetic functional fillers by way of electroplating Ni–Fe alloy method. The effects of cathode vibration frequency on the content of Ni–Fe alloy in the coating and the surface morphologies of the coatings were evaluated. The electromagnetic properties of the coated diatomite particles before and after heat treatment were also investigated in detail. The results show that the core-shell flake-shaped diatomite particles with high content of Ni–Fe alloy and good surface qualities of the coatings can be obtained by adjusting cathode vibration frequency. The coated diatomite particles with heat treatment filled paraffin wax composites exhibit a superior microwave absorbing and electromagnetic properties compared to the non-heat treated samples. Additionally, the peaks of reflection loss are found to be able to shift to lower frequency by the heat treatment process, which indicates the heat treatment can adjust microwave absorbing frequency band. - Highlights: • We used the diatomite particles as template to fabricate the flake-shaped ferromagnetic fillers. • The diatomite particles were deposited pure magnetic Ni–Fe alloy by electroplating methods. • The coated diatomite particles were lightweight ferromagnetic fillers. • The composites containing coated diatomite particles with heat treatment exhibited great potential in the field of electromagnetic absorbing.

Effect of cathode vibration and heat treatment on electromagnetic properties of flake-shaped diatomite coated with Ni–Fe alloy by electroplating

International Nuclear Information System (INIS)

Lan, Mingming; Li, Huiqin; Huang, Weihua; Xu, Guangyin; Li, Yan

2015-01-01

In this paper, flake-shaped diatomite particles were used as forming templates for the fabrication of the ferromagnetic functional fillers by way of electroplating Ni–Fe alloy method. The effects of cathode vibration frequency on the content of Ni–Fe alloy in the coating and the surface morphologies of the coatings were evaluated. The electromagnetic properties of the coated diatomite particles before and after heat treatment were also investigated in detail. The results show that the core-shell flake-shaped diatomite particles with high content of Ni–Fe alloy and good surface qualities of the coatings can be obtained by adjusting cathode vibration frequency. The coated diatomite particles with heat treatment filled paraffin wax composites exhibit a superior microwave absorbing and electromagnetic properties compared to the non-heat treated samples. Additionally, the peaks of reflection loss are found to be able to shift to lower frequency by the heat treatment process, which indicates the heat treatment can adjust microwave absorbing frequency band. - Highlights: • We used the diatomite particles as template to fabricate the flake-shaped ferromagnetic fillers. • The diatomite particles were deposited pure magnetic Ni–Fe alloy by electroplating methods. • The coated diatomite particles were lightweight ferromagnetic fillers. • The composites containing coated diatomite particles with heat treatment exhibited great potential in the field of electromagnetic absorbing

Reduction of Ochratoxin A in Oat Flakes by Twin-Screw Extrusion Processing.

Science.gov (United States)

Lee, Hyun Jung; Dahal, Samjhana; Perez, Enrique Garcia; Kowalski, Ryan Joseph; Ganjyal, Girish M; Ryu, Dojin

2017-10-01

Ochratoxin A (OTA) is one of the most important mycotoxins owing to its widespread occurrence and toxicity, including nephrotoxicity and potential carcinogenicity to humans. OTA has been detected in a wide range of agricultural commodities, including cereal grains and their processed products. In particular, oat-based products show a higher incidence and level of contamination. Extrusion cooking is widely used in the manufacturing of breakfast cereals and snacks and may reduce mycotoxins to varying degrees. Hence, the effects of extrusion cooking on the stability of OTA in spiked (100 μg/kg) oat flake was investigated by using a laboratory-scale twin-screw extruder with a central composite design. Factors examined were moisture content (20, 25, and 30% dry weight basis), temperature (140, 160, and 180°C), screw speed (150, 200, and 250 rpm), and die size (1.5, 2, and 3 mm). Both nonextruded and extruded samples were analyzed for reductions of OTA by high-performance liquid chromatography, coupled with fluorescence detection. The percentage of reductions in OTA in the contaminated oat flakes upon extrusion processing were in the range of 0 to 28%. OTA was partially stable during extrusion, with only screw speed and die size having significant effect on reduction (P < 0.005). The highest reduction of 28% was achieved at 180°C, 20% moisture, 250 rpm screw speed, and a 3-mm die with 193 kJ/kg specific mechanical energy. According to the central composite design analyses, up to 28% of OTA can be reduced by a combination of 162°C, 30% moisture, and 221 rpm, with a 3-mm die.

A microwave inverse Cerenkov Accelerator (MICA)

International Nuclear Information System (INIS)

Hirshfield, Jay L.

1999-01-01

The objective of this Phase II SBIR research program was to complete the final design originated during Phase I for a prototype Microwave Inverse Cerenkov Accelerator (MICA), to fabricate the-prototype MICA, and to test its performance as an electron accelerator. This report contains details of the design, predictions of accelerator performance, results of cold tests on the MICA structure, and details of the installation of MICA on the Yale Beam Physics Laboratory 6-MeV beamline. Discussion of future work is also included

Silver Flakes and Silver Dendrites for Hybrid Electrically Conductive Adhesives with Enhanced Conductivity

Science.gov (United States)

Ma, Hongru; Li, Zhuo; Tian, Xun; Yan, Shaocun; Li, Zhe; Guo, Xuhong; Ma, Yanqing; Ma, Lei

2018-03-01

Silver dendrites were prepared by a facile replacement reaction between silver nitrate and zinc microparticles of 20 μm in size. The influence of reactant molar ratio, reaction solution volume, silver nitrate concentration, and reaction time on the morphology of dendrites was investigated systematically. It was found that uniform tree-like silver structures are synthesized under the optimal conditions. Their structure can be described as a trunk, symmetrical branches, and leaves, which length scales of 5-10, 1-2 μm, and 100-300 nm, respectively. All features were systematically characterized by scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, and x-ray powder diffraction. A hybrid fillers system using silver flakes and dendrites as electrically conductive adhesives (ECAs) exhibited excellent overall performance. This good conductivity can be attributed mainly to the synergy between the silver microflakes (5-20 μm sized irregular sheet structures) and dendrites, allowing more conductive pathways to be formed between the fillers. In order to further optimize the overall electrical conductivity, various mixtures of silver microflakes and silver dendrites were tested in ECAs, with results indicating that the highest conductivity was shown when the amounts of silver microflakes, silver dendrites and the polymer matrix were 69.4 wt.% (20.82 vol.%), 0.6 wt.% (0.18 vol.%), and 30.0 wt.% (79.00 vol.%), respectively. The corresponding mass ratio of silver flakes to silver dendrites was 347:3. The resistivity of ECAs reached as low as 1.7 × 10-4 Ω cm.

Dynamics of magnetic nano-flake vortices in Newtonian fluids

Energy Technology Data Exchange (ETDEWEB)

Bazazzadeh, Nasim, E-mail: n.bazazzadeh@gmail.com [Department of Physics, Shahid Beheshti University, G.C., Evin, Tehran 19839 (Iran, Islamic Republic of); Mohseni, Seyed Majid, E-mail: m-mohseni@sbu.ac.ir [Department of Physics, Shahid Beheshti University, G.C., Evin, Tehran 19839 (Iran, Islamic Republic of); Khavasi, Amin, E-mail: khavasi@sharif.edu [Department of Electrical Engineering, Sharif University of Technology, Tehran 11555-4363 (Iran, Islamic Republic of); Zibaii, Mohammad Ismail, E-mail: mizibaye@gmail.com [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Evin, Tehran 19839 (Iran, Islamic Republic of); Movahed, S.M.S., E-mail: m_movahed@sbu.ac.ir [Department of Physics, Shahid Beheshti University, G.C., Evin, Tehran 19839 (Iran, Islamic Republic of); Jafari, G.R., E-mail: gjafari@gmail.com [Department of Physics, Shahid Beheshti University, G.C., Evin, Tehran 19839 (Iran, Islamic Republic of)

2016-12-01

We study the rotational motion of nano-flake ferromagnetic disks suspended in a Newtonian fluid, as a potential material owing the vortex-like magnetic configuration. Using analytical expressions for hydrodynamic, magnetic and Brownian torques, the stochastic angular momentum equation is determined in the dilute limit conditions under applied magnetic field. Results are compared against experimental ones and excellent agreement is observed. We also estimate the uncertainty in the orientation of the disks due to the Brownian torque when an external magnetic field aligns them. Interestingly, this uncertainty is roughly proportional to the ratio of thermal energy of fluid to the magnetic energy stored in the disks. Our approach can be implemented in many practical applications including biotechnology and multi-functional fluidics. - Highlights: • The rotational motion of magnetic-vortex microdiscs in a Newtonian fluid is studied. • Results are compared against experimental ones and excellent agreement is observed. • The uncertainty in the orientation of the microdiscs is analytically derived.

Thermophysical and rheological properties of dulce de leche with and without coconut flakes as a function of temperature

Directory of Open Access Journals (Sweden)

Vanessa Camarinha Barbosa

2013-03-01

Full Text Available Dulce de leche (DL, a dairy dessert highly appreciated in Brazil, is a concentrated product containing about 70% m/m of total solids. Thermophysical and rheological properties of two industrial Brazilian Dulce de leche formulations (classic Dulce de leche and Dulce de leche added with coconut flakes 1.5% m/m were determined at temperatures comprised between 28.4 and 76.4 °C. In general, no significant differences (p < 0.05 were observed in the presence of coconut flakes in the two formulations. Heat capacity varied from 2633.2 to 3101.8 J/kg.°C; thermal conductivity from 0.383 to 0.452 W/m.°C; specific mass from 1350.7 to 1310.7 kg/m³; and, thermal diffusivity from (1.082 × 10-7 to 1.130 × 10-7 m²/s. The Bingham model was used to properly describe the non-Newtonian behavior of both formulations, with yielding stress values varying from 27.3 to 17.6 Pa and plastic viscosity from 19.9 to 5.9 Pa.s.

Electronic properties of graphene nano-flakes: Energy gap, permanent dipole, termination effect, and Raman spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Singh, Sandeep Kumar, E-mail: SandeepKumar.Singh@uantwerpen.be; Peeters, F. M., E-mail: Francois.Peeters@uantwerpen.be [Department of Physics, University of Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium); Neek-Amal, M., E-mail: neekamal@srttu.edu [Department of Physics, University of Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium); Department of Physics, Shahid Rajaee Teacher Training University, Lavizan, Tehran 16788 (Iran, Islamic Republic of)

2014-02-21

The electronic properties of graphene nano-flakes (GNFs) with different edge passivation are investigated by using density functional theory. Passivation with F and H atoms is considered: C{sub N{sub c}} X{sub N{sub x}} (X = F or H). We studied GNFs with 10 < N{sub c} < 56 and limit ourselves to the lowest energy configurations. We found that: (i) the energy difference Δ between the highest occupied molecular orbital and the lowest unoccupied molecular orbital decreases with N{sub c}, (ii) topological defects (pentagon and heptagon) break the symmetry of the GNFs and enhance the electric polarization, (iii) the mutual interaction of bilayer GNFs can be understood by dipole-dipole interaction which were found sensitive to the relative orientation of the GNFs, (iv) the permanent dipoles depend on the edge terminated atom, while the energy gap is independent of it, and (v) the presence of heptagon and pentagon defects in the GNFs results in the largest difference between the energy of the spin-up and spin-down electrons which is larger for the H-passivated GNFs as compared to F-passivated GNFs. Our study shows clearly the effect of geometry, size, termination, and bilayer on the electronic properties of small GNFs. This study reveals important features of graphene nano-flakes which can be detected using Raman spectroscopy.

Suitability of Sites for Hazardous Waste Disposal, Concord Naval Weapons Station, Concord, California.

Science.gov (United States)

1987-09-01

mica flakes. The mica-bearing sandy soil Is most likely a product of riverine processes in the valley of the Sacramento - San Joaquin system and from a...Quad- rangle, Contra Costa County, California, US Geological Survey, Open-File Report 80-547. 0 _ 1980b. Preliminary geologic map of the Honker Bay...Quadrangle, Solano and Contra Costa Counties, California, US Geological Survey, Open-File Report 80-2009. * 1980c. Preliminary geologic map of the

Microwave properties of sphere-, flake-, and disc-shaped BaFe{sub 12}O{sub 19} nanoparticle inks for high-frequency applications on printed electronics

Energy Technology Data Exchange (ETDEWEB)

Myllymäki, S. [Microelectronics Research Unit, University of Oulu, Oulu 90014 (Finland); Maček Kržmanc, M. [Josef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia); Sloma, M. [Institute of Electronic Materials Technology (ITME) Department of Silicon Technology, 133 Wolczynska Street, 01-919 Warsaw (Poland); Juuti, J.; Nelo, M.; Teirikangas, M. [Microelectronics Research Unit, University of Oulu, Oulu 90014 (Finland); Jakubowska, M. [Institute of Electronic Materials Technology (ITME) Department of Silicon Technology, 133 Wolczynska Street, 01-919 Warsaw (Poland); Suvorov, D. [Josef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia); Jantunen, H. [Microelectronics Research Unit, University of Oulu, Oulu 90014 (Finland)

2016-12-01

Spherical (diameter 50–200 nm), flake- (diameter 40–200 nm), and disc-shaped (diameter 10–20 nm) BaFe{sub 12}O{sub 19} nanoparticles were synthesized with a wet chemical method, and their permittivity, electric loss tangent, permeability, and magnetic loss tangent were measured in the 0.045–10 GHz range. The materials were prepared using a solution of 12% PMMA resin in a butyldiglycol solvent for 10–50 wt% filling content. Microstrip transmission-line perturbation was used to measure complex permeability and the split post dielectric resonator method was employed to measure dielectric properties. The frequency dependence of the permeability and permittivity spectra of the composites was affected by their shape and filling fraction. The composites made with spherical particles had higher permeability values (1.4–1.75) at 1 GHz than the composites made with flake (1.25–1.6) or disc particles (1.1–1.3), but the spherical particles caused more losses. The flake particle composite provided permeability and magnetic loss characteristics at both 1 GHz and 7 GHz superior to those of the sphere particle composite in low-loss RF applications. The magnetic loss tangent of PMMA/BaFe{sub 12}O{sub 19} was 0.2–0.3 at 1 GHz, being lower than that of state-of-the-art PANI/BaFe{sub 12}O{sub 19} composites. The sphere composite inks showed permeability values less than 1 at 1–4 GHz ferromagnetic resonance (FMR); they could be used as a tunable material in microwave applications. The sphere and flake composite inks also had sufficient printing quality for the screen-printing fabrication method.

Nano-sized graphene flakes: insights from experimental synthesis and first principles calculations.

Science.gov (United States)

Lin, Pin-Chun; Chen, Yi-Rui; Hsu, Kuei-Ting; Lin, Tzu-Neng; Tung, Kuo-Lun; Shen, Ji-Lin; Liu, Wei-Ren

2017-03-01

In this study, we proposed a cost-effective method for preparing graphene nano-flakes (GNFs) derived from carbon nanotubes (CNTs) via three steps (pressing, homogenization and sonication exfoliation processes). Scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), laser scattering, as well as ultraviolet-visible and photoluminescence (PL) measurements were carried out. The results indicated that the size of as-synthesized GNFs was approximately 40-50 nm. Furthermore, we also used first principles calculations to understand the transformation from CNTs to GNFs from the viewpoints of the edge formation energies of GNFs in different shapes and sizes. The corresponding photoluminescence measurements of GNFs were carried out in this work.

21 CFR 73.1350 - Mica-based pearlescent pigments.

Science.gov (United States)

2010-04-01

... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1350 Mica-based pearlescent pigments. (a) Identity. (1) The color additive is formed by depositing titanium and/or iron salts onto mica, followed by...; titanium dioxide and iron oxide on mica. Mica used to manufacture the color additive shall conform in...

21 CFR 73.350 - Mica-based pearlescent pigments.

Science.gov (United States)

2010-04-01

... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.350 Mica-based pearlescent pigments. (a) Identity. (1) The color additive is formed by depositing titanium salts onto mica, followed by heating to produce titanium dioxide on mica. Mica used to manufacture the color additive shall conform in identity to...

MICA: The Meta-Institute for Computational Astrophysics

Science.gov (United States)

McMillan, Stephen L. W.; Djorgovski, S. G.; Hut, P.; Vesperini, E.; Knop, R.; Portegies Zwart, S.

2009-05-01

We describe MICA, the Meta Institute for Computational Astrophysics, the first professional scientific and educational, non-profit organization based in virtual worlds [VWs]. Most MICA activities are currently conducted in Second Life, arguably the most popular and best developed VW; we plan to expand our presence into other VWs as those venues evolve. The goals of MICA include (1) exploration, development and promotion of VWs and virtual reality [VR] technologies for professional research in astronomy and related fields; (2) development of novel networking venues and mechanisms for virtual scientific communication and interaction, including professional meetings, visualization, and telecollaboration; (3) use of VWs and VR technologies for education and public outreach; and (4) exchange of ideas and joint efforts with other scientific disciplines in promoting these goals for science and scholarship in general. We present representative example of MICA activities and achievements, and outline plans for expansion of the organization. For more information on MICA, please visit http://mica-vw.org .

Electromagnetic properties of core–shell particles by way of electroless Ni–Fe–P alloy plating on flake-shaped diatomite

Energy Technology Data Exchange (ETDEWEB)

Zhang, Deyuan [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China); Yuan, Liming, E-mail: lming_y@163.com [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China); Lan, Mingming; Hu, Yanyan; Cai, Jun [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China); Zhang, Wenqiang [College of Engineering, China Agricultural University, Beijing 100083 (China); Li, Haiyang [China Aerospace Science and Technology Corporation, Beijing 100854 (China)

2013-11-15

Flake-shaped diatomite particles coated by Ni–Fe–P alloy were prepared by electroless plating technique and processed by heat treatment. The samples were characterized by SEM, EDS and XRD. The results indicated that the magnetic diatomite particles had continuous and homogeneous Ni–Fe–P coating, and the phase constitution of the Ni–Fe–P coating was transformed from an amorphous structure to a crystalline structure during heat treatment. The measured electromagnetic parameters and the calculated reflection loss suggested that heat treatment was able to enhance the microwave absorption performance of the paraffin wax based composites. In a word, the Ni–Fe–P coated diatomite particle obtained in this paper is a promising candidate for lightweight microwave absorbing inclusions. - Highlights: • We used the flake-shaped diatomite particles as forming template to fabricate the core–shell ferromagnetic particles. • The diatomite particles were deposited Ni–Fe–P alloy by way of electroless plating methods. • The coated diatomite particles were lightweight ferromagnetic fillers. • The composites containing coated diatomite particles with heat treatment exhibited great potential in the field of electromagnetic absorbing.

Electromagnetic properties of core–shell particles by way of electroless Ni–Fe–P alloy plating on flake-shaped diatomite

International Nuclear Information System (INIS)

Zhang, Deyuan; Yuan, Liming; Lan, Mingming; Hu, Yanyan; Cai, Jun; Zhang, Wenqiang; Li, Haiyang

2013-01-01

Flake-shaped diatomite particles coated by Ni–Fe–P alloy were prepared by electroless plating technique and processed by heat treatment. The samples were characterized by SEM, EDS and XRD. The results indicated that the magnetic diatomite particles had continuous and homogeneous Ni–Fe–P coating, and the phase constitution of the Ni–Fe–P coating was transformed from an amorphous structure to a crystalline structure during heat treatment. The measured electromagnetic parameters and the calculated reflection loss suggested that heat treatment was able to enhance the microwave absorption performance of the paraffin wax based composites. In a word, the Ni–Fe–P coated diatomite particle obtained in this paper is a promising candidate for lightweight microwave absorbing inclusions. - Highlights: • We used the flake-shaped diatomite particles as forming template to fabricate the core–shell ferromagnetic particles. • The diatomite particles were deposited Ni–Fe–P alloy by way of electroless plating methods. • The coated diatomite particles were lightweight ferromagnetic fillers. • The composites containing coated diatomite particles with heat treatment exhibited great potential in the field of electromagnetic absorbing

Photoactivated Mixed In-Plane and Edge-Enriched p-Type MoS2 Flake-Based NO2 Sensor Working at Room Temperature.

Science.gov (United States)

Agrawal, Abhay V; Kumar, Rahul; Venkatesan, Swaminathan; Zakhidov, Alex; Yang, Guang; Bao, Jiming; Kumar, Mahesh; Kumar, Mukesh

2018-05-25

Toxic gases are produced during the burning of fossil fuels. Room temperature (RT) fast detection of toxic gases is still challenging. Recently, MoS 2 transition metal dichalcogenides have sparked great attention in the research community due to their performance in gas sensing applications. However, MoS 2 based gas sensors still suffer from long response and recovery times, especially at RT. Considering this challenge, here, we report photoactivated highly reversible and fast detection of NO 2 sensors at room temperature (RT) by using mixed in-plane and edge-enriched p-MoS 2 flakes (mixed MoS 2 ). The sensor showed fast response with good sensitivity of ∼10.36% for 10 ppm of NO 2 at RT without complete recovery. However, complete recovery was obtained with better sensor performance under UV light illumination at RT. The UV assisted NO 2 sensing showed improved performance in terms of fast response and recovery kinetics with enhanced sensitivity to 10 ppm NO 2 concentration. The sensor performance is also investigated under thermal energy, and a better sensor performance with reduced sensitivity and high selectivity toward NO 2 was observed. A detailed gas sensing mechanism based on the density functional theory (DFT) calculations for favorable NO 2 adsorption sites on in-plane and edge-enriched MoS 2 flakes is proposed. This study revealed the role of favorable adsorption sites in MoS 2 flakes for the enhanced interaction of target gases and developed a highly sensitive, reversible, and fast gas sensor for next-generation toxic gases at room temperature.

Acute Antibody-Mediated Rejection in Presence of MICA-DSA and Successful Renal Re-Transplant with Negative-MICA Virtual Crossmatch.

Directory of Open Access Journals (Sweden)

Yingzi Ming

Full Text Available The presence of donor-specific alloantibodies (DSAs against the MICA antigen results in high risk for antibody-mediated rejection (AMR of a transplanted kidney, especially in patients receiving a re-transplant. We describe the incidence of acute C4d+ AMR in a patient who had received a first kidney transplant with a zero HLA antigen mismatch. Retrospective analysis of post-transplant T and B cell crossmatches were negative, but a high level of MICA alloantibody was detected in sera collected both before and after transplant. The DSA against the first allograft mismatched MICA*018 was in the recipient. Flow cytometry and cytotoxicity tests with five samples of freshly isolated human umbilical vein endothelial cells demonstrated the alloantibody nature of patient's MICA-DSA. Prior to the second transplant, a MICA virtual crossmatch and T and B cell crossmatches were used to identify a suitable donor. The patient received a second kidney transplant, and allograft was functioning well at one-year follow-up. Our study indicates that MICA virtual crossmatch is important in selection of a kidney donor if the recipient has been sensitized with MICA antigens.

Nanomolar electrochemical detection of caffeic acid in fortified wine samples based on gold/palladium nanoparticles decorated graphene flakes.

Science.gov (United States)

Thangavelu, Kokulnathan; Raja, Nehru; Chen, Shen-Ming; Liao, Wei-Cheng

2017-09-01

Amalgamation of noble metal nanomaterials on graphene flakes potentially paves one way to improve their physicochemical properties. This paper deals with the simultaneous electrochemical deposition of gold and palladium nanoparticles on graphene flakes (Au/PdNPs-GRF) for the sensitive determination of caffeic acid (CA). The physiochemical properties of the prepared Au/PdNPs-GRF was characterized by using numerous analytical techniques such as scanning electron microscopy, electron dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray powder diffraction, Raman spectroscopy and electrochemical impedance spectroscopy. The enhanced electrochemical determination of CA at Au/PdNPs deposition on GRF were studied by using cyclic voltammetry and differential pulse voltammetry. In results, Au/PdNPs-GRF electrode exhibited an excellent electrocatalytic activity towards CA with wide linear range and low limit of detection of 0.03-938.97µM and 6nM, respectively. Eventually, the Au/PdNPs-GRF was found as a selective and stable active material for the sensing of CA. In addition, the proposed sensor showed the adequate results in real sample analysis. Copyright © 2017 Elsevier Inc. All rights reserved.

Purification of melt-spun metallurgical grade silicon micro-flakes through a multi-step segregation procedure

Science.gov (United States)

Martinsen, F. A.; Nordstrand, E. F.; Gibson, U. J.

2013-01-01

Melt-spun metallurgical grade (MG) micron dimension silicon flakes have been purified into near solar grade (SG) quality through a multi-step melting and re-solidification procedure. A wet oxidation-applied thermal oxide maintained the sample morphology during annealing while the interiors were melted and re-solidified. The small thickness of the flakes allowed for near elimination of in-plane grain boundaries, with segregation enhanced accumulation of impurities at the object surface and in the few remaining grain boundaries. A subsequent etch in 48% hydrofluoric acid (HF) removed the impure oxide layer, and part of the contamination at the oxide-silicon interface, as shown by electron dispersive spectroscopy (EDS) and backscattered electron imaging (BEI). The sample grains were investigated by electron back-scattered diffraction (EBSD) after varying numbers of oxidation-annealing-etch cycles, and were observed to grow from ˜5 μm to ˜200 μm. The concentration of iron, titanium, copper and aluminium were shown by secondary ion mass spectroscopy (SIMS) and inductively coupled plasma mass spectroscopy (ICPMS) to drop between five and six orders of magnitude. The concentration of boron was observed to drop approximately one order of magnitude. A good correlation was observed between impurity removal rates and segregation models, indicating that the purification effect is mainly caused by segregation. Deviations from these models could be explained by the formation of oxides and hydroxides later removed through etching.

Facile preparation and enhanced microwave absorption properties of flake carbonyl iron/Fe3O4 composite

International Nuclear Information System (INIS)

Min, Dandan; Zhou, Wancheng; Luo, Fa; Zhu, Dongmei

2017-01-01

Highlights: • Flake carbonyl iron/Fe 3 O 4 composites were prepared by surface oxidation technique. • Lower permittivity and modest permeability was obtained by the FCI/Fe 3 O 4 composites. • Enhanced absorption efficiency and broader absorption band were obtained. - Abstract: Flake carbonyl iron/Fe 3 O 4 (FCI/Fe 3 O 4 ) composites with enhanced microwave absorption properties were prepared by a direct and flexible surface oxidation technique. The phase structures, morphology, magnetic properties, frequency-dependent electromagnetic and microwave absorption properties of the composites were investigated. The measurement results showed that lower permittivity as well as modest permeability was obtained by the FCI/Fe 3 O 4 composites. The calculated microwave absorption properties indicated that enhanced absorption efficiency and broader absorption band were obtained by the FCI/Fe 3 O 4 composite comparing with the FCI composite. The absorption frequency range with reflection loss (RL) below −5 dB of FCI/Fe 3 O 4 composites at reaction time of 90 min at thickness of 1.5 mm is 13.3 GHz from 4.7 to 18 GHz, while the bandwidth of the FCI composite is only 5.9 GHz from 2.6 to 8.5 GHz at the same thickness. Thus, such absorbers could act as effective and wide broadband microwave absorbers in the GHz range.

Two-mica granites of northeastern Nevada.

Science.gov (United States)

Lee, D.E.; Kistler, R.W.; Friedman, I.; Van Loenen, R. E.

1981-01-01

The field settings are described and analytical data are presented for six two-mica granites from NE Nevada. High delta 18O and 87Sr/86Sr values indicate that all are S-type granite, derived from continental crust. The major element chemistry and accessory mineral contents of these rocks also are characteristic of S-type granites. Chemical, X ray, and other data are presented for the micas recovered from these granites. The muscovites are notably high in Fe2O3, FeO, and MgO. Except for one hydrobiotite, each of the biotites has an MgO content near 6.0 wt%. Two different types of two-mica granites are recognized in the area of this study. One type is distinguished by the presence of many biotite euhedra within muscovite phenocrysts and by an unusual suite of accessory minerals completely devoid of opaque oxides. This type probably resulted from anatexis of late Precambrian argillites under conditions of relatively low oxygen fugacity, along a line that roughly coincides with the westward disappearance of continental basement. In the other textural type of two-mica granite the micas are equigranular and there is a greater variety of accessory minerals. The magmatic evolution of this type also appears to reflect the influence of late Precambrian argillites; there may be age differences between the two types of two-mica granites.-Author

Effect of cathode vibration and heat treatment on electromagnetic properties of flake-shaped diatomite coated with Ni-Fe alloy by electroplating

Science.gov (United States)

Lan, Mingming; Li, Huiqin; Huang, Weihua; Xu, Guangyin; Li, Yan

2015-03-01

In this paper, flake-shaped diatomite particles were used as forming templates for the fabrication of the ferromagnetic functional fillers by way of electroplating Ni-Fe alloy method. The effects of cathode vibration frequency on the content of Ni-Fe alloy in the coating and the surface morphologies of the coatings were evaluated. The electromagnetic properties of the coated diatomite particles before and after heat treatment were also investigated in detail. The results show that the core-shell flake-shaped diatomite particles with high content of Ni-Fe alloy and good surface qualities of the coatings can be obtained by adjusting cathode vibration frequency. The coated diatomite particles with heat treatment filled paraffin wax composites exhibit a superior microwave absorbing and electromagnetic properties compared to the non-heat treated samples. Additionally, the peaks of reflection loss are found to be able to shift to lower frequency by the heat treatment process, which indicates the heat treatment can adjust microwave absorbing frequency band.

Optical emission spectroscopic study of Ar/H2/CH4 plasma during the production of graphene nano-flakes by induction plasma synthesis

International Nuclear Information System (INIS)

Mohanta, Antaryami; Lanfant, Briac; Asfaha, Mehari; Leparoux, Marc

2017-01-01

Graphene nano-flakes using CH 4 precursor were synthesized in a radio frequency inductively coupled plasma reactor with in-situ investigation of Ar/H 2 /CH 4 plasma by optical emission spectroscopy at fixed H 2 and Ar flow rates of 4 and 75 slpm, respectively, and at different plate powers (12 to 18 kW), pressures (400 to 700 mbar) and CH 4 flow rates (0.3 to 2 slpm). Emissions from C 2 Swan band, C 3 , CH and H 2 are observed in the optical emission spectra of Ar/H 2 /CH 4 plasma. Plasma temperature estimated analyzing the C 2 Swan band emission intensities is found to be decreased with increasing pressure and decreasing plate power. The decreasing plasma temperature gives rise to increase in production rate due to increase in condensation process. The production rate is observed to be increased from 0 to 0.3 g/h at 18 kW and from 0 to 1 g/h at 15 kW with increase in pressure from 400 to 700 mbar at fixed CH 4 flow rate of 0.7 slpm. Broad band continuum emission appears in the emission spectra at specific growth conditions in which the formation of vapor phase nanoparticles due to condensation of supersaturated vapor is facilitated. The production rate at 12 kW, 700 mbar, and 0.7 slpm of CH 4 flow rate is found to be 1.7 g/h which is more than that at 15 and 18 kW. Thus, the broadband continuum emission dominates the optical emission spectra at 12 kW due to lower temperature and higher production rate, and is attributed to the emission from suspended nanoparticles formed in vapor phase. The synthesized nanoparticles exhibit flake like structures having average length and width about 200 and 100 nm, respectively, irrespective of the growth conditions. Nano-flakes have thickness between 3.7 to 7.5 nm and are composed of 11 to 22 graphene layers depending on the growth conditions. The intensity ratio (I D /I G ) of D and G band observed in the Raman spectra is less than 0.33 which indicates good quality of the synthesized graphene nano-flakes. (paper)

Induced critical current density limit of Ag sheathed Bi-2223 tape conductor

International Nuclear Information System (INIS)

Ogiwara, H.; Satou, M.; Yamada, Y.; Kitamura, T.; Hasegawa, T.

1994-01-01

The authors have already reported the best critical current density of 66,000 A/cm 2 with an Ag sheathed Bi-2223 tape conductor. The Brick-wall model is for explaining the current transport mechanism of this conductor. The model has its roots in the fact that the Bi-2223 tape core is a complicated stack of crystals which have a mica-flake structure. The orientation of the crystals which have a mica-flake structure. The orientation of the crystals seriously affects the current transport capability. Moreover, the contacts between the stacking crystals are very important. The transport current flows dividing into many branch paths. Under high magnetic field, the different paths experienced different electromagnetic forces. Differences between the electromagnetic forces on the different crystals can affect the contacts so as to increase resistivity and decrease overall critical current density of the tape. This effect can foretell the limit of the critical current density obtainable with these kinds of conductors

Order of 17 May 1985 on treatment by ionizing radiation of gum-arabic, dehydrated vegetables and cereal flakes and seeds

International Nuclear Information System (INIS)

1985-01-01

This Order fixes the licensing conditions for the sale of gum-arabic, dehydrated vegetables and cereal flakes and seeds for use in dairy products, whose microbial decontamination was obtained through exposure to cobalt 60 or caesium 137 gamma-rays or electron beams with an energy below or equal to 10 MeV. (NEA) [fr

La coyuntura económica nacional

Directory of Open Access Journals (Sweden)

Arturo Huerta González

2003-01-01

Full Text Available El objetivo de este artículo es analizar los problemas de contracción económica que enfrenta nuestro país como resultado de la política económica predominante, que lo ha llevado a depender de la economía estadounidense. Cuando ésta enfrentó problemas de crecimiento también frenó el crecimiento de la economía nacional. El gobierno mexicano no instrumenta política fiscal anticíclica (expansión del gasto para contrarrestar la caída de exportaciones y recuperar la dinámica económica por considerar que ello originaría presiones sobre precios y el sector externo y pudiera llevar a un contexto de especulación y crisis. Es por esto que se opta por seguir priorizando políticas contraccionistas para evitar la inflación, como si éste fuese el principal problema del país. Asimismo, el gobierno insiste en las reformas estructurales (apertura eléctrica, petrolera, reforma fiscal y laboral para ampliar la esfera de influencia del sector privado nacional y extranjero y para consolidar el saneamiento fiscal y abaratar el costo de la fuerza de trabajo, impulsando así la dinámica económica. Sin embargo, tales reformas ya las hemos vivido —desde el gobierno de Salinas de Gortari a la fecha— y sus resultados han sido crecimientos espurios que han desembocado en crisis y en el actual estancamiento. Mientras prosiga la actual política económica seguirá deteriorándose la esfera productiva y aumentando el desempleo, sin que se logre un crecimiento sostenido y menos vulnerable de la economía

QUÍMICA VERDE: UN NUEVO RETO

Directory of Open Access Journals (Sweden)

Nerlis Paola Pájaro Castro

2011-01-01

Full Text Available En la actualidad, existe un enorme deterioro del medio ambiente que ha generado la necesidad de buscar alternativas que conduzcan a la sostenibilidad ambiental. Una de estas herramientas es la ¿química verde¿, concepto que contempla el diseño de productos y procesos que reduzcan la generación de sustancias peligrosas y maximicen la eficiencia en la utilización de recursos materiales y energéticos. El empleo de tecnologías menos contaminantes, permitirá a las empresas químicas mitigar los efectos ambientales asociados a su actividad, reduciendo el consumo de materiales e incrementando la participación de recursos renovables. Para alcanzar estas metas, se han propuesto 12 principios básicos de química verde, aplicables en diferentes campos, tales como la medicina, la agricultura, la industria química y farmacéutica. Esta revisión detalla los principios y usos principales de la química verde, y su aplicación como una filosofía de trabajo para avanzar hacia un verdadero desarrollo sostenible.

MICA: Multiple interval-based curve alignment

Science.gov (United States)

Mann, Martin; Kahle, Hans-Peter; Beck, Matthias; Bender, Bela Johannes; Spiecker, Heinrich; Backofen, Rolf

2018-01-01

MICA enables the automatic synchronization of discrete data curves. To this end, characteristic points of the curves' shapes are identified. These landmarks are used within a heuristic curve registration approach to align profile pairs by mapping similar characteristics onto each other. In combination with a progressive alignment scheme, this enables the computation of multiple curve alignments. Multiple curve alignments are needed to derive meaningful representative consensus data of measured time or data series. MICA was already successfully applied to generate representative profiles of tree growth data based on intra-annual wood density profiles or cell formation data. The MICA package provides a command-line and graphical user interface. The R interface enables the direct embedding of multiple curve alignment computation into larger analyses pipelines. Source code, binaries and documentation are freely available at https://github.com/BackofenLab/MICA

Paragenesis of Cr-rich muscovite and chlorite in green-mica ...

Indian Academy of Sciences (India)

peculiar green colour is attributed to the concen- tration of .... mica quartzite, 1g: white mica (paucity of green mica) with ..... lacking in the white micas. 6.2 Chlorites. Chlorites are associated with green micas in the. Palasgaon–Saigaon area. EPMA analysis of the representative chlorites has been obtained. Cations.

Algoritmos para genómica comparativa

OpenAIRE

Figueiras, Vasco da Rocha

2010-01-01

Com o surgimento da Genómica e da Proteómica, a Bioinformática conduziu a alguns dos avanços científicos mais relevantes do século XX. A Unidade de Investigação e Desenvolvimento do Biocant, parque biotecnológico de Cantanhede, assume actualmente o papel de motor no desenvolvimento da Genómica. O Biocant possui um importante sequenciador de larga escala que permite armazenar um elevado número de genomas, nomeadamente, genomas de bactérias. O estudo proposto reflecte a necessidade do Bio...

Hydrogen effect on mechanical properties and flake formation in the 10KhSND steel rolled plates

Energy Technology Data Exchange (ETDEWEB)

Muradova, R G; Zakharov, V A; Kuzin, A P; Gol' tsov, V A; Podgajskij, M S [Donetskij Politekhnicheskij Inst. (Ukrainian SSR); Donetskij Nauchno-Issledovatel' skij Inst. Chernoj Metallurgii (Ukrainian SSR))

1982-01-01

The effect of hydrogen on mechanical properties of the 10KhSND steel rolled plates during natural aging is studied. Optimum period of metal acceptance tests, which are advisable to conduct after 5-7 day natural aging of finished products, are found out. The technique is worked out and a safe hydrogen content to prevent flake formation in the 10KhSND steel is determined. It is shown that a safe hydrogen content is dependent on the experiment conditions (sample dimensions, conditions of cooling, and prehistory).

Hydrogen effect on mechanical properties and flake formation in the 10KhSND steel rolled plates

International Nuclear Information System (INIS)

Muradova, R.G.; Zakharov, V.A.; Kuzin, A.P.; Gol'tsov, V.A.; Podgajskij, M.S.

1982-01-01

The effect of hydrogen on mechanical properties of the 10KhSND steel rolled plates during natural aging is studied. Optimum period of metal acceptance tests, which are advisable to conduct after 5-7 day natural aging of finished products, are found out. The technique is worked out and a safe hydrogen content to prevent flake formation in the 10KhSND steel is determined. It is shown that a safe hydrogen content is dependent on the experiment conditions (sample dimensions, conditions of cooling, and prehistory)

Differences between tethered polyelectrolyte chains adsorbed onto bare mica and hydrophobically modified mica, comparison with theory.

Science.gov (United States)

Balastre, Marc; Tamashiro, Mario N.; Hernandez, Ernesto; Pincus, Philip; Tirrell, Matthew

2001-03-01

End-grafted polymers generated from the adsorption of asymmetric diblock copolymers on solid surface play an important role in many areas of science and technology. While the small insoluble block acts as an anchor, the charged soluble block confers useful properties to the surface. This study looks at tethered layers of poly(styrene sulfonate)/poly(t-butyl styrene) (PtBS-PSS) adsorbed on both mica (hydrophilic) and octadecyltriethoxysilane (OTE) modified mica (hydrophobic). Normal compressing forces at two different constant grafting densities (bare and modified mica) were measured with the surface force apparatus and compared with theoretical prediction. The effect of salt concentration (Cs) upon the thickness of the self-assembled layers (Lo) was measured in each case. For adsorption of diblock copolymers onto OTE the resulting scaling relationship is much closer to the brush theory, Lo Cs-1/3. This result suggests that the adsorbed amount on mica is not high enough to form a brush.

Thermal properties of polyethylene reinforced with recycled–poly (ethylene terephthalate) flakes.

Science.gov (United States)

Ruqiyah Nik Hassan, Nik; Mazni Ismail, Noor; Ghazali, Suriati; Nuruzzaman, Dewan Muhammad

2018-04-01

In this study, recycled plastic bottles (RPET) were used as a filler in high density polyethylene (HDPE) thermoplastic. The plastic sheet of RPET/HDPE was prepared by using hot and cold press machine. The effects of RPET addition and hot press process to the thermal properties of the composite RPET/HDPE were investigated using differential scanning calorimetry (DSC) and thermogravimetric (TGA). Results from DSC analysis show that the melting point of HDPE slightly shifted to a higher temperature for about 2°C to 4°C with the addition of RPET as a filler. The starting degradation temperature of RPET/HDPE composite examined from TGA analysis also seen to be slightly increased. It was observed that the incorporation of recycled PET flakes into HDPE is achievable using hot press process with slight improvement seen in both melting point and thermal stability of the composite compared to the neat HDPE.

Química general II

OpenAIRE

Olba Torrent, Amparo

2018-01-01

El document forma part dels materials docents programats mitjançant l'ajut del Servei de Política Lingüística de la Universitat de València Temes de l'assignatura: Química general II del primer curs del Grau de Química Topics of the course: General Chemistry II in the first year of the Degree in Chemistry

La enseñanza de la química desde la perspectiva de la Química Verde

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Pía José González García

2016-06-01

Full Text Available La Química Verde, como área de investigación, se comprende como el desarrollo de metodologías para modificar los productos o procesos con la finalidad de reducir o eliminar los riesgos que existen para el medio ambiente y la salud. De este modo, permite proyectar líneas de investigación en la construcción de un conocimiento y enfoques didácticos de las ciencias, y  para ser considerada como parte de los programas Ministeriales. El objetivo del estudio fue conocer y comprender el significado que le otorgan los(as docentes del área a la Química Verde como perspectiva para su enseñanza. A partir de los discursos emanados por los docentes participantes del estudio, se construyeron 4 categorías, las cuales son: la Química Verde como: contexto para la enseñanza de la química, medio de apropiación significativo del aprendizaje de la química, motivadora de la conciencia ambiental y reflejo de la Institución y su relación con los docentes. The teaching of chemistry from the Green Chemistry perspective Green Chemistry (GC, as a research area, understood as the development of methodologies to modify products or processes in order to reduce or eliminate the risks posed to the environment and human health. Thus it is allowing research project lines in building knowledge and didactic approaches of the sciences, and to be considered as part of the ministerial programs. The objective of this study was to know and understand the significance given by teachers in the area to GC as a perspective for education. From the speeches issued by teachers participating in the study, four categories, was built. GC as: context for teaching chemistry, through significant learning chemistry appropriation, motivating environmental awareness and reflection of the institution and its relationship with teachers.  O ensino de química, na perspectiva da Química verde A Química verde, como área de investigação, é compreendida como o desenvolvimento de

Flake like V_2O_5 nanoparticles for ethanol sensing at room temperature

International Nuclear Information System (INIS)

Chitra, M.; Uthayarani, K.; Rajasekaran, N.; Neelakandeswari, N.; Girija, E. K.; Padiyan, D. Pathinettam

2016-01-01

The versatile redox property of vanadium oxide explores it in various applications like catalysis, electrochromism, electrochemistry, energy storage, sensors, microelectronics, batteries etc., In this present work, vanadium oxide was prepared via hydrothermal route followed by calcination. The structural and lattice parameters were analysed from the powder X-ray diffraction (XRD) pattern. The morphology and the composition of the sample were obtained from Field emission Scanning electron microscopic (FeSEM) and Energy Dispersive X-ray (EDAX) Spectrometric analysis respectively. The sensitivity, response – recovery time of the sample towards ethanol (0 ppm – 300 ppm) sensing at room temperature was measured and the present investigation on vanadium oxide nanoparticles over the flakes shows better sensitivity (30%) at room temperature.

Influence of segregations and hydrogen flakes on the mechanical properties of forged RPV steels

International Nuclear Information System (INIS)

Eiselt, C.C.; May, J.; Hein, H.

2013-01-01

In the frame of relevant 1970s/80s German research programs (e.g. FKS research program on component safety and others), many investigations on large forgings manufactured from Reactor Pressure Vessel (RPV) materials such as 20 MnMoNi 5 5 and 22 NiMoCr 3 7 have been performed. Lately, after ultrasonic testing hydrogen flakes in connection with segregation zones have been observed in a few RPV forgings. The earlier R and D programs contained a number of special heats, which covered a defined defect state (lower bound heats) with relevance to the recent observations of numerous UT indications in RPV forgings of two PWRs. Therefore, the results of these former research programs were now reviewed. The studies included an evaluation of the effects of macro/micro segregations as well as hydrogen flakes on the mechanical properties. As part of the mechanical technological experiments Charpy impact tests in different orientations (e.g. L-T, T-L and S-T) together with fracture mechanics and large scale tensile tests were carried out in segregated and non segregated material zones. In this context the letters L,T,S indicate the longitudinal, transversal and short transverse (thickness) direction with respect to rolling direction of the forging axis. The first letter indicates the direction of the principal stress, while the second letter stands for the crack propagation direction [1]. Furthermore the irradiation behavior of segregated material regions was analyzed and compared to non segregated material regions. Key results of these analyses indicate that in most cases upper shelf levels are lowered in segregated material parts compared to non segregated areas. In addition the segregations cause a larger scattering of impact energies. A high hydrogen content in combination with segregations has overall detrimental effects on the mechanical properties. However, there seems to be no specific segregation influence on the materials' irradiation reaction.

Uniform hexagonal graphene flakes and films grown on liquid copper surface.

Science.gov (United States)

Geng, Dechao; Wu, Bin; Guo, Yunlong; Huang, Liping; Xue, Yunzhou; Chen, Jianyi; Yu, Gui; Jiang, Lang; Hu, Wenping; Liu, Yunqi

2012-05-22

Unresolved problems associated with the production of graphene materials include the need for greater control over layer number, crystallinity, size, edge structure and spatial orientation, and a better understanding of the underlying mechanisms. Here we report a chemical vapor deposition approach that allows the direct synthesis of uniform single-layered, large-size (up to 10,000 μm(2)), spatially self-aligned, and single-crystalline hexagonal graphene flakes (HGFs) and their continuous films on liquid Cu surfaces. Employing a liquid Cu surface completely eliminates the grain boundaries in solid polycrystalline Cu, resulting in a uniform nucleation distribution and low graphene nucleation density, but also enables self-assembly of HGFs into compact and ordered structures. These HGFs show an average two-dimensional resistivity of 609 ± 200 Ω and saturation current density of 0.96 ± 0.15 mA/μm, demonstrating their good conductivity and capability for carrying high current density.

BIOÉTICA Y GENÓMICA BIOÉTICA E GENÔMICA BIOETHICS AND GENOMICS

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José Alberto Mainetti

2003-01-01

Full Text Available Los avances científicos en el campo de la genómica abren las puertas a los fantasmas de la humanidad. Por esto, el Proyecto Genoma Humano (PGH ha sido el primer gran proyecto de investigación internacional que ha tenido un subproyecto sobre la problemática ética, legal y social asociada al mismo: Ethical, Legal, and Social Issues (ELSI. Esta preocupación bioética surgió como espacio de dilucidación de las diferentes preocupaciones éticas y sociales que nacían a la par de los avances de la genómica. La genómica, expresada como la clave que revelará el misterio del ser (la lámpara de Aladino o como la herramienta de destrucción ecológica, el determinismo genético, el reduccionismo genético y la eugenesia, es decir, como la caja de Pandora. El PGH posee un incalculable valor para el diagnóstico de nuevas enfermedades, nuevos fármacos y nuevas terapias, pero abre también riesgos y temores que han de ser estudiados y analizados desde una perspectiva más amplia que la científicotécnica, es decir, como una reflexión bioética sobre la genómicaOs avanços científicos no campo da genômica abrem as portas aos fantasmas da humanidade. Por isso, o Projeto Genoma Humano (PGH foi o primeiro grande projeto de pesquisa internacional que teve um subprojeto sobre a problemática ética, legal e social associada ao mesmo. Esta preocupação bioética surgiu como espaço de elucidação das diferentes preocupações éticas e sociais que surgiam ao par dos avanços da genômica. A genômica, expressa como a chave que revelará o mistério do ser ( a lâmpada de Aladim ou como a ferramenta de destruição ecológica, o determinismo gen´tico, o reducionismo genético e a eugenésia, isto é, como a caixa de Pandora. O PGH possui um incalculável valor para o diagnóstico de novas enfermidades, novos fármacos e novas terapias, porém abrem também riscos e temores que devem ser estudados e analisados numa perspectiva mais ampla que a

Production and exchange during the Portuguese Chalcolitic: the case of bifacial flaked stone industries

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Forenbaher, Stašo

1998-12-01

Full Text Available This study focuses on the economic organization of bifacial flaked stone industries of the Late Neolithic/Chalcolithic Portugal. It is often claimed that social hierarchies first appeared in Western Iberia during this period (ca. 3500-2500 BC. The specific research goals are: determining the production repertoire at lithic production sites, examining the possibility of craft specialization (with particular regard to artifact standardization, and investigating the geographic distribution of artifacts, in order to detect evidence of centralization. The analyses show that the organization of economy differed markedly between different artifact classes. Production of subsistence-related lithics was decentralized and they circulated through local exchange networks, although some of them could enter long-distance exchange. Prestige-related items were exchanged over large distances and apparently were produced by specialists. The level of specialization and its importance for the economy remained modest. There is no evidence for large-scale sociopolitical integration.

Este estudio se centra en la organización económica de las industrias líticas de talla bifacial del Neolítico Final/ Calcolítico en Portugal. Se ha defendido a menudo que las jerarquías sociales aparecieron por primera vez en el occidente de la Península Ibérica durante este periodo (ca. 3500-2500 AC. Los objetivos específicos de la investigación son: determinar el repertorio de la producción en los talleres líticos, examinar la posibilidad de una especialización artesanal (prestando particular atención a la estandarización artefactual, e investigar la distribución geográfica de los artefactos para detectar las evidencias de centralización. Los análisis muestran que la organización de la economía difiere de forma notable entre las distintas clases de artefactos. La producción de los instrumentos conectados con la subsistencia era descentralizada. Los útiles

Effects of sorghum wet distillers grains plus solubles in steam-flaked corn-based finishing diets on steer performance, carcass characteristics, and digestibility characteristics

Science.gov (United States)

Two studies were conducted to evaluate the effects of sorghum wet distillers grains (SWDGS) in finishing diets on steer performance, carcass characteristics, and nutrient digestibility. In Exp. 1, 240 steers (initial BW = 379 +/-1 kg) were fed steam-flaked corn (SFC)-based diets with or without 25%...

Atomically flat platinum films grown on synthetic mica

Science.gov (United States)

Tanaka, Hiroyuki; Taniguchi, Masateru

2018-04-01

Atomically flat platinum thin films were heteroepitaxially grown on synthetic fluorophlogopite mica [KMg3(AlSi3O10)F2] by van der Waals epitaxy. Platinum films deposited on a fluorophlogopite mica substrate by inductively coupled plasma-assisted sputtering with oxygen introduction on a synthetic mica substrate resulted in the growth of twin single-crystalline epitaxial Pt(111) films.

Malvaceae endémicas del Perú

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Magda Chanco

2013-10-01

Full Text Available La familia Malvaceae es reconocida en el Perú con 38 géneros y 264 especies (Brako & Zarucchi 1993, Ulloa et al. 2004, mayormente arbustos y hierbas. En este trabajo reconocemos 87 especies endémicas en 16 géneros. El género más rico en especies endémicas es Nototriche. Las especies endémicas se encuentran en varias regiones ecológicas, entre ellas Altoandina, Mesoandina y Puna Húmeda y Seca, por encima de los 2500 m, hasta alcanzar los límites de la vegetación a 5100 m de altitud. Se aplicaron las categorías y criterios de la UICN a 84 especies. Once especies endémicas se encuentran presentes en el Sistema Nacional de Áreas Naturales Protegidas por el Estado.

Vochysiaceae endémicas del Perú

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Blanca León

2013-10-01

Full Text Available La familia Vochysiaceae es reconocida en el Perú por presentar cuatro géneros y 32 especies (Brako & Zarucchi, 1993; Ulloa Ulloa et al., 2004, todas árboles. En este trabajo reconocemos dos especies endémicas en el género Qualea. Estas especies endémicas han sido encontradas en la región Bosques Húmedos Amazónicos, entre los 100 y 160 m de altitud. Ninguna especie endémica se encuentra representada dentro del Sistema Nacional de Áreas Naturales Protegidas por el Estado.

Mineral resource of the month: vermiculite

Science.gov (United States)

Tanner, Arnold O.

2014-01-01

Vermiculite comprises a group of hydrated, laminar magnesium-aluminum-iron silicate minerals resembling mica. They are secondary minerals, typically altered biotite, iron-rich phlogopite or other micas or clay-like minerals that are themselves sometimes alteration products of amphibole, chlorite, olivine and pyroxene. Vermiculite deposits are associated with volcanic ultramafic rocks rich in magnesium silicate minerals, and flakes of the mineral range in color from black to shades of brown and yellow. The crystal structure of vermiculite contains water molecules, a property that is critical to its processing for common uses.

Mechanistic Indicators of Childhood Asthma (MICA) Study

Science.gov (United States)

The Mechanistic Indicators of Childhood Asthma (MICA) Study has been designed to incorporate state-of-the-art technologies to examine the physiological and environmental factors that interact to increase the risk of asthmatic responses. MICA is primarily a clinically-bases obser...

A Highly Ion-Selective Zeolite Flake Layer on Porous Membranes for Flow Battery Applications.

Science.gov (United States)

Yuan, Zhizhang; Zhu, Xiangxue; Li, Mingrun; Lu, Wenjing; Li, Xianfeng; Zhang, Huamin

2016-02-24

Zeolites are crystalline microporous aluminosilicates with periodic arrangements of cages and well-defined channels, which make them very suitable for separating ions of different sizes, and thus also for use in battery applications. Herein, an ultra-thin ZSM-35 zeolite flake was introduced onto a poly(ether sulfone) based porous membrane. The pore size of the zeolite (ca. 0.5 nm) is intermediary between that of hydrated vanadium ions (>0.6 nm) and protons (99 % and an energy efficiency of >81 % at 200 mA cm(-2), which is by far the highest value ever reported. These convincing results indicate that zeolite-coated membranes are promising in battery applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Moraceae endémicas del Perú

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Pamela Cáceres

2013-10-01

Full Text Available La familia Moraceae es reconocida en el Perú por presentar 19 géneros y 128 especies (Brako & Zarucchi, 1993; Ulloa Ulloa et al., 2004, la mayoría arbóreas y/o hemiepífitos. En este trabajo reconocemos dos especies endémicas en igual número de géneros. Las especies endémicas se encuentran en la región Bosques Húmedos Amazónicos, entre los 115 y 220 m de altitud. Ambas especies endémicas se encuentran dentro del Sistema Nacional de Áreas Naturales Protegidas por el Estado.

Rosaceae endémicas del Perú

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Wilfredo Mendoza

2013-10-01

Full Text Available La familia Rosaceae es reconocida en el Perú por presentar 24 géneros y 113 especies (Brako & Zarucchi, 1993; Mendoza, 2005; Ulloa Ulloa et al., 2004, entre hierbas, arbustos y árboles. En este trabajo reconocemos 14 especies endémicas en cuatro géneros. Las especies endémicas se encuentran principalmente en las regiones Bosques Pluviales Montanos, Bosques Muy Húmedos Montanos y Páramo, entre los 1900 y 3800 m de altitud. Seis especies endémicas se encuentran representadas dentro del Sistema Nacional de Áreas Naturales Protegidas por el Estado.

Facile synthesis, growth mechanism and reversible superhydrophobic and superhydrophilic properties of non-flaking CuO nanowires grown from porous copper substrates

International Nuclear Information System (INIS)

Zhang Qiaobao; Xu Daguo; Zhang Kaili; Hung, Tak Fu

2013-01-01

Reversible superhydrophobic and superhydrophilic surfaces based on porous substrates covered with CuO nanowires are developed in this study. A facile thermal oxidation method is used to synthesize non-flaking bicrystalline CuO nanowires on porous copper substrates in static air. The effects of thermal oxidation temperature and duration are systemically studied. The growth mechanism of the obtained non-flaking CuO nanowires is presented and the compression stress is believed to be the key driving force. The wettability of the CuO nanowires after chemical modification with trichloro(1H,1H,2H,2H-perfluorooctyl)silane is systemically investigated. The porous substrates covered with CuO nanowires exhibit excellent superhydrophobic performance with almost no water adhesion and no apparent drag resistance, and a maximum static water contact angle of 162 ± 2° is observed. Moreover, a rapid reversibly switchable wettability between superhydrophobic and superhydrophilic states is realized by the alternation of air–plasma treatment and surface fluorination. The porous substrates covered with CuO nanowires will find promising applications in surface and corrosion protection, liquid transportation, oil–water separation, and self-cleaning surfaces. (paper)

Recovery from Iridium-192 flakes of a radioactive source for industrial use after a radiation incident; Recuperacion de hojuelas de Iridio-192 provenientes de una fuente radiactivas de uso industrial despues de un incidente radiologico

Energy Technology Data Exchange (ETDEWEB)

Cruz, W.H.; Zapata, L.A., E-mail: wcruz@ipen.gob.pe, E-mail: lzapata@ipen.gob.pe [Instituto Peruano de Energia Nuclear (GRRA/IPEN), Lima (Peru). Division de Gestion de Residuos Radiactivos

2013-07-01

The Iridium-192 ({sup 192}Ir) is the most used and ideal for industrial radiography applications, especially in petrochemical plants and pipelines and provides better contrast sensitivity for thick (25.4 mm). This source has constructive sealed double encapsulation, the internal capsule containing stainless steel to radioactive material in the form of flakes and welded with TIG process. The radiological incident happened at a gas station fuel sales in circumstances in which there was a homogeneity test welds a tank, the flakes or Ir-192 fell off his ponytail and left scattered over an area of 2 m{sup 2}, some fell flat areas and other land so collected in lead shielding and metal container and ground source. Full recovery of the leaflets was performed at the Division of radioactive waste management (GRRA) gaining a total of 22 flakes with no radiation risk to staff performance and installation and the conclusion was reached that the misapplicaion of TIG welding was the main cause the incident. (author)

Highly charged swelling mica reduces Cu bioavailability in Cu-contaminated soils

Energy Technology Data Exchange (ETDEWEB)

Stuckey, Jason W. [Department of Crop and Soil Sciences, Pennsylvania State University, 116 ASI Building, University Park, PA 16802 (United States); Neaman, Alexander [Facultad de Agronomia, P. Universidad Catolica de Valparaiso, Centro Regional de Estudios en Alimentos Saludables (Chile); Ravella, Ramesh; Komarneni, Sridhar [Department of Crop and Soil Sciences, Pennsylvania State University, 116 ASI Building, University Park, PA 16802 (United States); Martinez, Carmen Enid [Department of Crop and Soil Sciences, Pennsylvania State University, 116 ASI Building, University Park, PA 16802 (United States)], E-mail: cem17@psu.edu

2009-01-15

This is the first test of a highly charged swelling mica's (Na-2-mica) ability to reduce the plant-absorbed Cu in Cu-contaminated soils from Chile. Perennial ryegrass (Lolium perenne L.) was grown in two acid soils (Sector 2: pH 4.2, total Cu = 172 mg Cu kg{sup -1} and Sector 3: pH 4.2, total Cu = 112 mg Cu kg{sup -1}) amended with 0.5% and 1% (w/w) mica, and 1% (w/w) montmorillonite. At 10 weeks of growth, both mica treatments decreased the shoot Cu of ryegrass grown in Sector 2 producing shoot Cu concentrations above 21-22 mg Cu kg{sup -1} (the phytotoxicity threshold for that species), yet the mica treatments did not reduce shoot Cu concentrations when grown in Sector 3, which were at a typical level. The mica treatments improved shoot growth in Sector 3 by reducing free and extractable Cu to low enough levels where other nutrients could compete for plant absorption and translocation. In addition, the mica treatments improved root growth in both soils, and the 1% mica treatment reduced root Cu in both soils. This swelling mica warrants further testing of its ability to assist re-vegetation and reduce Cu bioavailability in Cu-contaminated surface soils. - In situ remediation of Cu-contaminated soils with a synthetic mica (Na-2-mica) will aid in re-vegetative efforts.

Efek Waktu Wet Milling dan Suhu Annealing Terhadap Sifat Fisis, Mikrostruktur dan Magnet dari Flakes NdFeB

OpenAIRE

Sipahutar, Wahyu Solafide

2015-01-01

Had made research manufacture NdFeB magnets of flakes of wet milling process using a ball mill to the physic properties, microstructure, and magnetic properties with variations milling time is 16 hours, 24 hours, 48 hours, 72 hours. Powder result of mechanical milling using a ball mill and then analyzed the resulting particle size by using PSA and XRD. Then do the manufacture of test samples in the form of pellets by compaction process through print isotropy. Having obtained a sample of pelle...

DNA adsorption and desorption on mica surface studied by atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Sun Lanlan [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Graduate school of the Chinese Academy of Sciences, Chinese Academy of Sciences, Renmin Street 5625, Changchun 130022 (China); Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 16 East Nan-Hu Road, Open Economic Zone, Changchun 130033 (China); Zhao Dongxu [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 16 East Nan-Hu Road, Open Economic Zone, Changchun 130033 (China); Zhang Yue; Xu Fugang [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Graduate school of the Chinese Academy of Sciences, Chinese Academy of Sciences, Renmin Street 5625, Changchun 130022 (China); Li Zhuang, E-mail: zli@ciac.jl.cn [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Graduate school of the Chinese Academy of Sciences, Chinese Academy of Sciences, Renmin Street 5625, Changchun 130022 (China)

2011-05-15

The adsorption of DNA molecules on mica surface and the following desorption of DNA molecules at ethanol-mica interface were studied using atomic force microscopy. By changing DNA concentration, different morphologies on mica surface have been observed. A very uniform and orderly monolayer of DNA molecules was constructed on the mica surface with a DNA concentration of 30 ng/{mu}L. When the samples were immersed into ethanol for about 15 min, various desorption degree of DNA from mica (0-99%) was achieved. It was found that with the increase of DNA concentration, the desorption degree of DNA from the mica at ethanol-mica interface decreased. And when the uniform and orderly DNA monolayers were formed on the mica surface, almost no DNA molecule desorbed from the mica surface in this process. The results indicated that the uniform and orderly DNA monolayer is one of the most stable DNA structures formed on the mica surface. In addition, we have studied the structure change of DNA molecules after desorbed from the mica surface with atomic force microscopy, and found that the desorption might be ascribed to the ethanol-induced DNA condensation.

DNA adsorption and desorption on mica surface studied by atomic force microscopy

International Nuclear Information System (INIS)

Sun Lanlan; Zhao Dongxu; Zhang Yue; Xu Fugang; Li Zhuang

2011-01-01

The adsorption of DNA molecules on mica surface and the following desorption of DNA molecules at ethanol-mica interface were studied using atomic force microscopy. By changing DNA concentration, different morphologies on mica surface have been observed. A very uniform and orderly monolayer of DNA molecules was constructed on the mica surface with a DNA concentration of 30 ng/μL. When the samples were immersed into ethanol for about 15 min, various desorption degree of DNA from mica (0-99%) was achieved. It was found that with the increase of DNA concentration, the desorption degree of DNA from the mica at ethanol-mica interface decreased. And when the uniform and orderly DNA monolayers were formed on the mica surface, almost no DNA molecule desorbed from the mica surface in this process. The results indicated that the uniform and orderly DNA monolayer is one of the most stable DNA structures formed on the mica surface. In addition, we have studied the structure change of DNA molecules after desorbed from the mica surface with atomic force microscopy, and found that the desorption might be ascribed to the ethanol-induced DNA condensation.

La Industria Química: Importancia y Retos

Directory of Open Access Journals (Sweden)

Nancy Montes-Valencia

2015-06-01

Full Text Available La química siempre ha estado presente en la vida del hombre para satisfacer sus necesidades y mejorar su calidad de vida. Hoy en día la industria química es un importante sector industrial presente en la mayoría de países, que dinamiza el crecimiento económico, genera empleo y ofrece diversidad de productos, no obstante produce contaminación al medio ambiente y utiliza recursos naturales no renovables. Por lo tanto surge el concepto de química verde como respuesta a la problemática ambiental cuya estructura es la sostenibilidad, siendo su principal objetivo prevenir la generación de emisiones y armonizar la química con los recursos naturales. Existe un gran reto para la industria química y es encontrar fuentes alternativas de energía para no seguir dependiendo del petróleo, el gas natural y el carbón, una de estas es el uso de la biomasa para la obtención de combustibles líquidos.

Printable elastic conductors by in situ formation of silver nanoparticles from silver flakes

Science.gov (United States)

Matsuhisa, Naoji; Inoue, Daishi; Zalar, Peter; Jin, Hanbit; Matsuba, Yorishige; Itoh, Akira; Yokota, Tomoyuki; Hashizume, Daisuke; Someya, Takao

2017-08-01

Printable elastic conductors promise large-area stretchable sensor/actuator networks for healthcare, wearables and robotics. Elastomers with metal nanoparticles are one of the best approaches to achieve high performance, but large-area utilization is limited by difficulties in their processability. Here we report a printable elastic conductor containing Ag nanoparticles that are formed in situ, solely by mixing micrometre-sized Ag flakes, fluorine rubbers, and surfactant. Our printable elastic composites exhibit conductivity higher than 4,000 S cm-1 (highest value: 6,168 S cm-1) at 0% strain, and 935 S cm-1 when stretched up to 400%. Ag nanoparticle formation is influenced by the surfactant, heating processes, and elastomer molecular weight, resulting in a drastic improvement of conductivity. Fully printed sensor networks for stretchable robots are demonstrated, sensing pressure and temperature accurately, even when stretched over 250%.

Flake structured SnSbCo/MCMB/C composite as high performance anodes for lithium ion battery

Energy Technology Data Exchange (ETDEWEB)

Chen, Xiaoqiu [School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006 (China); Engineering Research Center of Materials and Technology for Electrochemical Energy Storage (Ministry of Education), Guangzhou 510006 (China); Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006 (China); Guangdong Engineering Technology Research Center of Low Carbon and Advanced Energy Materials, Guangzhou 510631 (China); Ru, Qiang, E-mail: rq7702@yeah.net [School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006 (China); Engineering Research Center of Materials and Technology for Electrochemical Energy Storage (Ministry of Education), Guangzhou 510006 (China); Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006 (China); Guangdong Engineering Technology Research Center of Low Carbon and Advanced Energy Materials, Guangzhou 510631 (China); Zhao, Doudou; Mo, Yudi; Hu, Shejun [School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006 (China); Engineering Research Center of Materials and Technology for Electrochemical Energy Storage (Ministry of Education), Guangzhou 510006 (China); Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006 (China); Guangdong Engineering Technology Research Center of Low Carbon and Advanced Energy Materials, Guangzhou 510631 (China)

2015-10-15

SnSbCo/MCMB/C composite with flake structure were prepared by stepwise synthesis method. Firstly, SnSbCo nanoparticles were fabricated by co-precipitation, and then nanosized SnSbCo alloy were embedded in mesocarbon microbeads (MCMB) by ball-milling to synthesize primitive SnSbCo/MCMB hybrids, followed by carbonization of phenolic resin to produce an outer layer of carbon coating. The crystal structure, morphology and electrochemical properties of the SnSbCo/MCMB/C composite were evaluated by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and galvanostatical cycling tests. Compared with bare SnSbCo alloy and SnSbCo/MCMB hybrids, the efficiently enhanced electrochemical performance of SnSbCo/MCMB/C composite were mainly ascribed to the improved electron conductivity and volume buffering effect provided by the amorphous carbon coating. The resultant SnSbCo/MCMB/C composite delivered an initial discharge capacity of 848 mAh g{sup −1} under 100 mA g{sup −1}, with a good capacity retention of 85.6% after 70 cycles. The composite also exhibited excellent rate capability of 603 mAh g{sup −1} and 405 mAh g{sup −1} at the current density of 200 mA g{sup −1} and 1000 mA g{sup −1}, respectively. - Highlights: • Flake structured SnSbCo/MCMB/C composite have been prepared by stepwise synthesis method. • SnSbCo/MCMB/C composite show good cycle performance and rate capability. • Using both MCMB and phenolic resin as dual carbon sources.

“Nadie es profeta en su tierra”: Etnografía económica de las dinámicas comerciales de los Kichwa-Otavalo en San Victorino, Bogotá

OpenAIRE

López Ávila, Diego Felipe

2015-01-01

La presente monografía describe las dinámicas económicas de los Kichwas Otavalo en la zona comercial de San Victorino, Bogotá. Dichas dinámicas son examinadas a partir de la Nueva Sociología Económica (Smelser & Swedberg, 2005) y la Etnografía Económica (Dufy & Weber, 2009) para mostrar las divergentes racionalidades que surgen al interior del mercado. Esto nos lleva a debatir con la ciencia económica ortodoxa y los supuestos que manejan frente a la racionalidad, el mercado y la competencia....

Effect of forming process by using external magnetic field of bonded magnet made from NdFeB flakes to microstructure and magnetic properties

Science.gov (United States)

Suprapedi; Sardjono, P.; Muljadi; Djauhari, N. R.; Ramlan

2018-03-01

Research of fabricated bonded magnets NdFeB made from NdFeB flakes with variation of external magnetic field has been done. The materials preparation process begins with milling NdFeB flakes using High Energy Milling (HEM) for 60 minutes and mixing it with 5 wt % celuna binder and performing compaction to form pellet with a pressure of 40 Kgf/cm2 and then applying external magnetic field (0, 2000, 5000, 8000 and 11000 Gauss). The pellet samples were then dried using vacuum dryer with temperature of 100 °C for 1 hour. Characterization includes bulk density, measurement of magnetic properties with gauss meter, and Vibrating Sample Magnetometer (VSM). From the characterization results the best value was obtained on the external magnetic field orientation of 8000 to 11000 Gauss with a density value of 5.38 g/cm3, flux magnetic value of 465.9 – 467.1 Gauss, remanence value of 2.63–2.776 kGauss, and coercivity value of 1.905–1.925 kOe.

Onagraceae endémicas del Perú

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Susy Castillo

2013-10-01

Full Text Available Esta es la familia de las «fucsias», la cual es reconocida en el Perú por presentar seis géneros y 76 especies (Brako & Zarucchi, 1993; Ulloa Ulloa et al., 2004, principalmente arbustos y hierbas. En este trabajo reconocemos 24 especies endémicas, la mayoría en el género Fuchsia. Las especies endémicas se encuentran mayormente en la región Bosques Muy Húmedos Montanos, entre los 1600 y 2500 m de altitud. Diez especies endémicas se encuentran representados dentro del Sistema Nacional de Áreas Naturales Protegidas por el Estado.

Inhalation Toxicity of Cogenerated Graphite Flake and Fog Oil Smoke in the Brown-Headed Cowbird and the Red-Winged Blackbird, Size-Specific Inhalation Surrogates for the Red-Cockaged Woodpecker

National Research Council Canada - National Science Library

Driver, Crystal; Fulton, Robert; Ollero, Jennifer; Clark, Mark; Dennis, Gary; Tiller, Brett; Balbach, Harold E

2005-01-01

.... Conducting maneuvers under obscurant cover is important for realistic training. Generators that combine fog oil for visual obscuration with graphite flakes for infrared obscuration are being deployed for training scenarios...

Facile preparation and enhanced microwave absorption properties of flake carbonyl iron/Fe{sub 3}O{sub 4} composite

Energy Technology Data Exchange (ETDEWEB)

Min, Dandan, E-mail: mdd4776@126.com; Zhou, Wancheng; Luo, Fa; Zhu, Dongmei

2017-08-01

Highlights: • Flake carbonyl iron/Fe{sub 3}O{sub 4} composites were prepared by surface oxidation technique. • Lower permittivity and modest permeability was obtained by the FCI/Fe{sub 3}O{sub 4} composites. • Enhanced absorption efficiency and broader absorption band were obtained. - Abstract: Flake carbonyl iron/Fe{sub 3}O{sub 4} (FCI/Fe{sub 3}O{sub 4}) composites with enhanced microwave absorption properties were prepared by a direct and flexible surface oxidation technique. The phase structures, morphology, magnetic properties, frequency-dependent electromagnetic and microwave absorption properties of the composites were investigated. The measurement results showed that lower permittivity as well as modest permeability was obtained by the FCI/Fe{sub 3}O{sub 4} composites. The calculated microwave absorption properties indicated that enhanced absorption efficiency and broader absorption band were obtained by the FCI/Fe{sub 3}O{sub 4} composite comparing with the FCI composite. The absorption frequency range with reflection loss (RL) below −5 dB of FCI/Fe{sub 3}O{sub 4} composites at reaction time of 90 min at thickness of 1.5 mm is 13.3 GHz from 4.7 to 18 GHz, while the bandwidth of the FCI composite is only 5.9 GHz from 2.6 to 8.5 GHz at the same thickness. Thus, such absorbers could act as effective and wide broadband microwave absorbers in the GHz range.

Competitividad Sistémica. Niveles analíticos para el fortalecimiento de sectores de actividad económica

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Juliana Ferrer

2005-01-01

Full Text Available Un desarrollo industrial exitoso no se logra meramente considerando la función de producción en el nivel microeconómico, o las condiciones macroeconómicas estables; sino también por la existencia de medidas específicas del gobierno y de organizaciones privadas de desarrollo, orientadas a fortalecer la competitividad de los sectores de actividad económica. Además, la capacidad de vincular las iniciativas, está en función de un conjunto de estructuras político- económicas y de factores socioculturales y patrones básicos de organización, que caracterizan el proceso sistémico de competitividad de cada país. Se concluye que existe una marcada desarticulación entre los niveles de competitividad sistémica; reflejada por una incoherencia entre las políticas de Estado, los requerimientos de sectores de actividad y el reflejo de la necesidad real de las comunidades cada vez más desprovistas de recursos. Se recomienda la necesidad de superar la ardua fase que representa establecer una economía de mercado dirigida a mejorar la condición de vida de la población; por lo que será importante facilitar procesos autónomos de búsqueda y aprendizaje significativos, para el desarrollo de la competitividad de los sectores de actividad económica latinoamericanos.

APRENDIENDO ELECTROQUÍMICA. UN ESTUDIO COMPARATIVO

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Maria I. Vera

2011-01-01

Full Text Available Se realizó un seguimiento del proceso de enseñanza y aprendizaje de Electroquímica y se compararon los resultados obtenidos en evaluaciones parciales, con el objetivo de analizar si existen diferencias significativas en la apropiación de contenidos entre alumnos de carreras con diferentes perfiles. Se trabajó en los años 2009 y 2010 con dos grupos de alumnos en cada año, pertenecientes a carreras químicas y no químicas respectivamente. En ambos grupos se desarrollaron, con la misma carga horaria, contenidos conceptuales y procedimentales en clases teóricas con prácticas de resolución de problemas y de laboratorio. Para la evaluación se presentaron idénticas situaciones problemáticas, cuyos resultados muestran diferencias no significativas entre ambos grupos en la identificación del cátodo y del ánodo y cálculo de la fem estándar de la celda; en cambio en la aplicación de la Ecuación de Nernst y la identificación de especies químicas que reaccionan en los electrodos, hay diferencias significativas en las respuestas dadas.

Preparation of mica/apatite glass-ceramics biomaterials

International Nuclear Information System (INIS)

Liu Yong; Sheng Xiaoxian; Dan Xiaohong; Xiang Qijun

2006-01-01

Glass-ceramics have become more and more important biomaterials. In this work mica glass/apatite composites with various compositions were prepared by casting and subsequent heat treatments. The effects of composition, phase constitution and crystallinity on mechanical properties, including elastic modulus and transverse rupture strength (TRS), were investigated by using X-ray diffraction analyses (XRD), scanning electron microscopy (SEM) and mechanical tests. Results show that addition of apatite composition in mica glass accelerates the crystallization process and induces the formation of fluoroapatite phase, and the nucleation of apatite crystals occurs before that of mica crystals. The fuoroapatite in this work is needle-like, which is almost the same to that in human bone. The transverse rupture strength increases with the content of fluoroapatite and the crystallinity increasing, except that at a low apatite content the mechanical properties are lower than those of mica glass under the same processing conditions. The transverse rupture strength and elastic modulus obtained in this work fall in the range of those of human bone. SBF immersion test demonstrates good bioactivity of this biomaterial

Trayectorias evolucionistas en la dinámica de la empresa: una aproximación por dinámica de sistemas

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Germán Eduardo Vargas

2006-05-01

Full Text Available La actividad de las firmas, como unidad socioeconómica, en el marco evolucionista está orientada integralmente por procesos de identidad, cohesión y mecanismos de adaptación y evolución; en este orden, el presente documento ilustra, a través de un modelo por dinámica de sistemas, cómo la orientación e integración estratégica basada en el conocimiento para la innovación se constituye como un imperativo de desarrollo que, a partir de un pequeño apalancamiento, permite distinguir entre dos trayectorias de evolución, a saber: firmas económicas tradicionales (inerciales, pues introducen mejoras incrementales esporádicas y modernas (dinámicas y radicalmente innovadoras, hecho a partir del cual se obtienen reveladoras conclusiones y desafíos para intervenir y adecuar el comportamiento de las empresas.2

Scanning electron microscopic study of hazardous waste flakes of polyethylene terephthalate (PET) by aminolysis and ammonolysis

Energy Technology Data Exchange (ETDEWEB)

Mittal, Alok, E-mail: aljymittal@yahoo.co.in [Department of Chemistry, Maulana Azad National Institute of Technology (A Deemed University), Bhopal 462051 (India); Soni, R.K.; Dutt, Krishna; Singh, Swati [Department of Chemistry, Ch. Charan Singh University, Meerut 250004 (India)

2010-06-15

Polyethylene terephthalate (PET) waste flakes were degraded with aqueous methylamine and aqueous ammonia, respectively at room temperature in the presence and absence of quaternary ammonium salt as a catalyst for different periods of time. The aminolysed and ammonolysed PET samples were investigated for the surface morphology with the help of scanning electron micrograph (SEM). It shows that the semi-crystalline PET waste samples reduce to monodisperse rods before fully degradation to the end products. The presence of the catalyst provides site for degradation of PET waste and enhances the rate of degradation. The SEM shows early developments of fissures in comparison to the one in absence of quaternary ammonium salt used as catalyst.

Scanning electron microscopic study of hazardous waste flakes of polyethylene terephthalate (PET) by aminolysis and ammonolysis

International Nuclear Information System (INIS)

Mittal, Alok; Soni, R.K.; Dutt, Krishna; Singh, Swati

2010-01-01

Polyethylene terephthalate (PET) waste flakes were degraded with aqueous methylamine and aqueous ammonia, respectively at room temperature in the presence and absence of quaternary ammonium salt as a catalyst for different periods of time. The aminolysed and ammonolysed PET samples were investigated for the surface morphology with the help of scanning electron micrograph (SEM). It shows that the semi-crystalline PET waste samples reduce to monodisperse rods before fully degradation to the end products. The presence of the catalyst provides site for degradation of PET waste and enhances the rate of degradation. The SEM shows early developments of fissures in comparison to the one in absence of quaternary ammonium salt used as catalyst.

Major histocompatibility complex class I-related chain A/B (MICA/B) expression in tumor tissue and serum of pancreatic cancer: Role of uric acid accumulation in gemcitabine-induced MICA/B expression

International Nuclear Information System (INIS)

Xu, Xiulong; Rao, Geetha S; Groh, Veronika; Spies, Thomas; Gattuso, Paolo; Kaufman, Howard L; Plate, Janet; Prinz, Richard A

2011-01-01

Major histocompatibility complex class I-related chain A and B (MICA/B) are two stress-inducible ligands that bind the immunoreceptor NKG2D and play an important role in mediating the cyotoxicity of NK and T cells. In this study, we sought to study MICA/B expression in pancreatic cancer and to determine whether and how genotoxic drugs such as gemcitabine can affect MICA/B expression and natural killer cytotoxity. Seven pancreatic cancer cell lines were analyzed for MICA/B expression by flow cytometry and for their sensitivity to NK-92 cell killing by a 51 Cr release assay. MICA/B expression in tumor tissues and sera of pancreatic cancer was analyzed by immunohistochemical staining (IHC) and ELISA, respectively. Two MICA/B-positive cell lines were sensitive to the cytotoxic activity of NK-92 cells. Other two MICA/B-positive cell lines and three MICA/B-negative cell lines were resistant to NK-92 cell killing. MICA/B expression was positive in 17 of 25 (68%) pancreatic ductal adenocarcinomas but not in normal pancreatic ductal epithelial cells. Serum MICA/B levels were significantly elevated in patients with pancreatic adenocarcinomas but did not correlate with the stage of pancreatic cancer and patient survival. Gemcitabine therapy led to increased serum MICA levels in 6 of 10 patients with detectable serum MICA. Allopurinol, an inhibitor of xanthine oxidoreductase that converts xanthine to uric acid, blocked uric acid production, MICA/B expression, and sensitivity to NK-92 cell killing toward a PANC-1 cancer cell line exposed to radiation and two genotoxic drugs, gemcitabine and 5-fluorouracil. The levels of MICA/B expression in serum and tissue of pancreatic cancer are elevated. DNA damage-induced MICA/B expression is mediated through increased uric acid production

Major histocompatibility complex class I-related chain A/B (MICA/B expression in tumor tissue and serum of pancreatic cancer: Role of uric acid accumulation in gemcitabine-induced MICA/B expression

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Kaufman Howard L

2011-05-01

Full Text Available Abstract Background Major histocompatibility complex class I-related chain A and B (MICA/B are two stress-inducible ligands that bind the immunoreceptor NKG2D and play an important role in mediating the cyotoxicity of NK and T cells. In this study, we sought to study MICA/B expression in pancreatic cancer and to determine whether and how genotoxic drugs such as gemcitabine can affect MICA/B expression and natural killer cytotoxity. Methods Seven pancreatic cancer cell lines were analyzed for MICA/B expression by flow cytometry and for their sensitivity to NK-92 cell killing by a 51Cr release assay. MICA/B expression in tumor tissues and sera of pancreatic cancer was analyzed by immunohistochemical staining (IHC and ELISA, respectively. Results Two MICA/B-positive cell lines were sensitive to the cytotoxic activity of NK-92 cells. Other two MICA/B-positive cell lines and three MICA/B-negative cell lines were resistant to NK-92 cell killing. MICA/B expression was positive in 17 of 25 (68% pancreatic ductal adenocarcinomas but not in normal pancreatic ductal epithelial cells. Serum MICA/B levels were significantly elevated in patients with pancreatic adenocarcinomas but did not correlate with the stage of pancreatic cancer and patient survival. Gemcitabine therapy led to increased serum MICA levels in 6 of 10 patients with detectable serum MICA. Allopurinol, an inhibitor of xanthine oxidoreductase that converts xanthine to uric acid, blocked uric acid production, MICA/B expression, and sensitivity to NK-92 cell killing toward a PANC-1 cancer cell line exposed to radiation and two genotoxic drugs, gemcitabine and 5-fluorouracil. Conclusions The levels of MICA/B expression in serum and tissue of pancreatic cancer are elevated. DNA damage-induced MICA/B expression is mediated through increased uric acid production.

Algunas reflexiones sobre la distancia entre "hablar química" y "comprender química"

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Lydia Raquel Galagovsky

2014-12-01

Full Text Available Una clase de química puede ser considerada como un espacio de comunicación entre el docente experto y los estudiantes novatos, donde los lenguajes utilizados son la interfase explícita y observable del intercambio comunicativo. En el presente trabajo se muestra con dos ejemplos cómo la diversidad de lenguajes químicos en lugar de favorecer la comprensión de los estudiantes, puede actuar como fuente de obstáculos que dificultan la comunicación en el aula. Así mismo, se analizará con otros dos ejemplos cómo el discurso con el que se enseña la disciplina también es potencial generador de errores en los estudiantes, cuando ellos construyen sus modelos mentales idiosincrásicos a partir de un discurso recortado y simplificado, desde las mejores intenciones de realizar buenas transposiciones didácticas. Se plantea que un enfoque de análisis de la situación de aula como un encuentro comunicativo entre experto y novato conduce a una necesaria diferenciación entre "hablar química" y "comprender química".

Preparation and characterization of aluminum based alloy - mica composites

International Nuclear Information System (INIS)

Rashid, M.A.; Shamim, A.

1999-01-01

In this work, six pallets each of 2.0 cm dia and 0.5 cm thickness were prepared by powder metallurgy; half of them also contained 1% mica-powder to form a composite. Inclusion of mica resulted in a decreased density and an increased porosity of the sample. Brinell hardness was found to be 21% less for the composite than for the pure alloy. Micro-graphs of different areas of the sample show uniform distribution of mica particles and avoids around them. (author)

Microstructures and luminescent properties of Ce-doped transparent mica glass-ceramics

International Nuclear Information System (INIS)

Taruta, Seiichi; Iwasaki, Yoshitomo; Nishikiori, Hiromasa; Yamakami, Tomohiko; Yamaguchi, Tomohiro; Kitajima, Kunio; Okada, Kiyoshi

2012-01-01

Highlights: ► Ce-doped transparent glass-ceramics and their parent glasses. ► TEM and STEM images for the microstructures. ► Each mica crystal did not contain Ce uniformly. ► Emission due to Ce 3+ ions in the glass phase and/or Ce 3+ ions in the mica crystals. - Abstract: Transparent mica glass-ceramics were prepared by heating parent glasses that had been doped with 0.5–15 mol% CeO 2 . During the melting and heat treatment, Ce 4+ ions in the specimens were reduced to Ce 3+ ions, and one or both of these ion species were then replaced with Li + ions in the interlayers of the separated mica crystals. However, scanning transmission electron microscope (STEM) and Z-contrast imaging revealed that the mica crystals did not contain the same amount of Ce. On excitation at 254 nm, the parent glasses and glass-ceramics emitted blue light, which originated from the 5d to 4f transition of the Ce 3+ ions. The emission of the glass-ceramic containing a smaller amount of Ce was attributed to the Ce 3+ ions in both the glass phase and the mica crystals, whereas that of the glass-ceramics containing a larger amount of Ce was caused mainly by Ce 3+ ions in the mica crystals. The dependence of the emission band of the parent glasses on the amount of Ce was a unique feature of the Ce-doped transparent mica glass-ceramics and was not observed in previous studies of Eu-doped parent glasses and mica glass-ceramics.

Gentianaceae endémicas del Perú

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Susy Castillo

2013-10-01

Full Text Available La familia Gentianaceae es reconocida en el Perú por presentar alrededor de 15 géneros y aproximadamente de 170 especies (Brako & Zarucchi, 1993; Ulloa Ulloa et al., 2004; S. Castillo, com.pers., mayormente hierbas y arbustos. En este trabajo se reconoce 103 especies endémicas en siete géneros. Los géneros con mayor número de especies endemicas son Gentianella y Macrocarpaea. Las especies endémicas ocupan principalmente las regiones de la Puna Húmeda y Seca, Páramo y Bosque Muy Húmedo Montano, entre los 1000 y 5100 m de altitud. Se aplicaron las categorías y criterios de la UICN a 99 especies. Treinta y tres especies endémicas se encuentran representadas dentro de un área protegida.

Química de Heterociclos. Quinolina e isoquinolina

OpenAIRE

Collado, Daniel

2014-01-01

Quinolinas e isoquinolinas: propiedades. Reactividad química: SEAr, SNAr. Reacciones en cadenas laterales. Reacciones de quinolinio e isoquinolinio. Síntesis de quinolinas e isoquinolinas. Otros ciclos. Capítulo sexto de temario de la Asignatura Ampliación de Química Orgánica Avanzada. Quinolina e isoquinolina.

Synthesis and Characterization of Rutile TiO_2 Powder by the Sulfuric Acid Method

International Nuclear Information System (INIS)

Choi, Soon Ok; Cho, Jee Hee; Lim, Sung Hwan; Kim, Won Yong

2012-01-01

We investigated the experimental method that uses the homogeneous precipitation method to prepare mica flakes-coated rutile-type titania pearlescent pigment with urea as a precipitant. TiO_2 particles exhibit a high reflection of lights and optical properties with chemical stabilities, so they are appropriate for coating on luminescent pigments (mica). The coating principle of mica coated titania with various thicknesses was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and tested by spectrophotometer. Mica with a particle size in the range of 40-60 um was suspended in water, and metal sulphates and urea were added to the mixture, which was heated to boiling. The change in pH was continuously followed. The metal oxide and crystal structure were affected by the conditions of TiOSO_4 concentration and reaction time with a sintering temperature the range of 800-1100°C.

Rudimentary simple, single step fabrication of nano-flakes like AgCd alloy electro-catalyst for oxygen reduction reaction in alkaline fuel cell

International Nuclear Information System (INIS)

Bhandary, Nimai; Basu, Suddhasatwa; Ingole, Pravin P.

2016-01-01

In this work, for the first time, we report rudimentary simple, single step fabrication of an electro-catalyst based on AgCd alloy nanoparticles with flakes like geometry which shows highly efficient activity towards oxygen reduction reaction (ORR). A simple potentiostatic deposition method has been employed for co-depositing AgCd alloy nanostructures with flakes like shapes along with dendrites on the surface of carbon fibre paper. The chemico-physical properties of the catalyst are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDXS). Electro-catalytic activity of AgCd alloy based electro-catalyst towards ORR is studied in alkaline medium by cyclic voltammetry and rotating ring disk electrode (RRDE) technique. Electrochemical in-situ FTIR measurements are also performed to identify the species generated during ORR process. Based on the results from electro-catalysis experiment, it is concluded that nano-alloyed AgCd electrodeposited on carbon paper shows excellent activity for ORR, following four electron pathways with H_2O_2 yield less than 15%. The combination of low cost of Ag and Cd, fast and facile method of its fabrication and higher activity towards ORR makes the AgCd electro-catalyst an attractive catalyst of choice for alkaline fuel cell.

ANALOGIAS EM LIVROS DIDÁTICOS DESTINADOS AO ENSINO SUPERIOR: QUÍMICA ORGÂNICA VERSUS FÍSICO-QUÍMICA

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Josué Martins Gonçalves

2016-12-01

Full Text Available Os livros didáticos de Química, via de regra, fazem uso de analogias por se tratar de uma disciplina que envolve inúmeros conceitos abstratos. No entanto, há pouca pesquisa envolvendo identificação e explicação sobre as analogias utilizadas em livros didáticos direcionados ao ensino superior. Nesse sentido, o presente trabalho apresenta um estudo comparativo entre as analogias encontradas em livros de Química Orgânica e Físico-química destinados a estudantes do ensino superior. Foram identificadas 277 analogias nos livros analisados e categorizadas conforme sistemas adaptados de Thiele e Treagust (1994 e Francisco Junior (2009.Uma forma de abordagem mais adequada de utilização das analogias nesses livros foi realizada, bem como a verificação da importância do papel dos professores no uso desse recurso didático. Os resultados indicam que esses livros são ricos em analogias simples, dando ênfase às análogos estruturais no caso de livros de Química Orgânica e análogos funcionais nos de Físico-Química. As analogias simples são mais fáceis de induzirem os alunos a erros conceituais, pois mostram poucas similaridades entre os domínios comparados. É importante ressaltar que nesta pesquisa observa-se uma baixa ocorrência de analogias em que o autor do livro reconhece as limitações e/ou discute estas, repassando toda a responsabilidade ao professor e ao aluno no que se refere à explicação e percepção das analogias, respectivamente. É mister afirmar que muitas das analogias encontradas em alguns capítulos dos livros analisados, poderiam ser suprimidas sem perda significativa da compreensão dos conceitos abordados.

CONFLICTO, VIOLENCIA SOCIOECONÓMICA Y DESPLAZAMIENTO FORZADO EN COLOMBIA

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Andrés Felipe Mora Cortés

2013-12-01

Full Text Available Este artículo introduce el concepto de violencia socioeconómica, que se refiere a mecanismos de regulación de conflictos distributivos y prácticas gubernamentales que eliminan las condiciones base para la reproducción de la vida. Se identifican tres expresiones clave de la violencia socioeconómica: el despojo, la inseguridad económica y la no generación de oportunidades. El artículo insiste en el efecto desproporcionado que dichas expresiones de violencia socioeconómica tienen sobre la población desplazada; también defiende la necesidad de una agenda mínima que erradique la violencia como lógica reguladora de los conflictos distributivos y que sirva de base para la construcción de paz con justicia social en Colombia.

Synthesis and Characterization of Anatase TiO_2 Powder using a Homogeneous Precipitation Method

International Nuclear Information System (INIS)

Choi, Soon Ok; Cho, Jee Hee; Lim, Sung Hwan; Chung, Eun Young

2011-01-01

This paper studies the experimental method that uses the homogeneous precipitation method to prepare mica flakes coated with anatase-type titania pearlescent pigment with urea as precipitant. The optimum technology parameters, the chemical composition, the microstructure, and the color property of resulting pigments are discussed. The coating principle of mica coated titania with various coating thickness is analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy(TEM) and tested by spectrophotometer analysis. The colored nanocrystalline pigments with different morphology and coating thickness 45-170 nm were prepared by homogeneous precipitation treatment of TiOSO_4(titanum oxysulfate) aqueous solutions. Characterizations on the pigments show that the pearlescent effects of the pigments depend mainly on mica size, thickness of the metal oxide deposit, its chemical composition, and crystal structure.

Moessbauer spectra of white micas from the Central Western Carpathians Mountains

International Nuclear Information System (INIS)

Sitek, J; Toth, I; Sulak, M; Putis, M

2010-01-01

Potassium white micas from the rocks included into Cretaceous deformation zones (ca. 100-70 Ma in age) of the Central Western Carpathians were investigated by Moessbauer spectroscopy. White micas formed during a polystage evolution and changing P-T conditions of their crystallization in crustal-scale shear zones. We found criteria for distinguishing generations of celadonite-poor (muscovitic) and celadonite-rich (phengitic) white micas using Moessbauer spectroscopy. This method revealed contrasting spectra characterized by typical quadrupole doublets corresponding to Fe 2+ Fe 3+ contents in white micas. They are in the range of 2.9-3.0 mm/s for phengite, and 2.6-2.7 mm/s for muscovite. Moessbauer spectra reflect well the chemical changes in white mica aggregates, especially of those close to the end-member muscovite and (alumino-)celadonite compositions.

Moessbauer spectra of white micas from the Central Western Carpathians Mountains

Energy Technology Data Exchange (ETDEWEB)

Sitek, J; Toth, I [Department of Nuclear Physics and Technology, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovicova 3, Bratislava (Slovakia); Sulak, M; Putis, M, E-mail: jozef.sitek@stuba.s [Department of of Mineralogy and Petrology, Faculty of Natural Sciences, Comenius University Bratislava, Mlynska dolina G, 842 15 Bratislava (Slovakia)

2010-03-01

Potassium white micas from the rocks included into Cretaceous deformation zones (ca. 100-70 Ma in age) of the Central Western Carpathians were investigated by Moessbauer spectroscopy. White micas formed during a polystage evolution and changing P-T conditions of their crystallization in crustal-scale shear zones. We found criteria for distinguishing generations of celadonite-poor (muscovitic) and celadonite-rich (phengitic) white micas using Moessbauer spectroscopy. This method revealed contrasting spectra characterized by typical quadrupole doublets corresponding to Fe{sup 2+} Fe{sup 3+} contents in white micas. They are in the range of 2.9-3.0 mm/s for phengite, and 2.6-2.7 mm/s for muscovite. Moessbauer spectra reflect well the chemical changes in white mica aggregates, especially of those close to the end-member muscovite and (alumino-)celadonite compositions.

Prognostic value of MICA/B in cancers: a systematic review and meta-analysis.

Science.gov (United States)

Zhao, Yijing; Chen, Naifei; Yu, Yu; Zhou, Lili; Niu, Chao; Liu, Yudi; Tian, Huimin; Lv, Zheng; Han, Fujun; Cui, Jiuwei

2017-11-10

MHC class I chain related-proteins A (MICA) and B (MICB) are natural killer group 2D ligands that mediate tumor surveillance. Several studies have suggested that MICA/B levels predict clinical outcomes in patients with cancer; however, this remains contentious. Here, we present a systematic review and meta-analysis of available studies of the prognostic value of MICA/B in cancer. We searched PubMed, Embase, Clinicaltrials.gov, and Cochrane Library to identify studies published from inception to July 2017 that assessed MICA/B in patients with cancer. The hazard ratio (HR) and 95% confidence interval (CI) of MICA/B were extracted for overall survival (OS) analysis. A total of 19 studies comprising 2,588 patients with 10 different types of cancer were included in the study. Low sMICA/B levels were found associated with significantly longer OS (HR = 1.65, 95% CI [1.42-1.92], P < 0.00001). Patients with cancers of digestive system that exhibited high MICA/B expression had significantly longer OS in (HR = 0.56, 95% CI [0.39-0.80], P = 0.002) compared with those with lower MICA/B expression ( I 2 = 35%, P = 0.18). Serum soluble MICA/B represents a potential prognostic marker in various human cancers. High cell-surface MICA/B expression in cancers of the digestive system was found associated with increased survival.

Phyllitic minerals in hydrothermal uranium deposits. I. Crystalchemistry of relict and newly formed micas

International Nuclear Information System (INIS)

Leroy, Jacques; Cathelineau, Michel

1982-01-01

Several generations of white micas have been recognised in four two mica granite massifs which are associated with uranium deposits in the Hercynian chain. These different generations correspond to distinct geological phenomena belonging to the deuteric and hydrothermal stages of the history of these massifs. Crystalchemical studies of these micas with the aid of the electronic microprobe show that each of these phenomena corresponds a phengite of different, well defined compositions. An increase in the phengitic character and a decrease in the paragonite component are observed over time. Strong similarities exist between micas of the same generation belonging to different granite massifs. The study of the evolution of the earliest deuteric micas during later hydrothermal phenomena, mica episyenitisation and deposition of pitchblende, has shown two opposed trends. In the case of mica episyenitisation, the micas tend to reequilibrate, while in the case of pitchblende deposition and the vein stage in general, the micas preserve their primary character [fr

Limiting Size of Monolayer Graphene Flakes Grown on Silicon Carbide or via Chemical Vapor Deposition on Different Substrates

Science.gov (United States)

Alekseev, N. I.

2018-05-01

The maximum size of homogeneous monolayer graphene flakes that form during the high-temperature evaporation of silicon from a surface of SiC or during graphene synthesis via chemical vapor deposition is estimated, based on the theoretical calculations developed in this work. Conditions conducive to the fragmentation of a monolayer graphene sheet to form discrete fragments or terrace-type structures in which excess energy due to dangling bonds at the edges is compensated for by the lack of internal stress are indentified and described. The results from calculations for the sizes of graphene structures are compared with experimental findings for the most successful graphene syntheses reported in the literature.

Graphene Visualizes the Ion Distribution on Air-Cleaved mica

NARCIS (Netherlands)

Bampoulis, Pantelis; Sotthewes, Kai; Siekman, Martin Herman; Zandvliet, Henricus J.W.; Poelsema, Bene

2017-01-01

The distribution of potassium (K+) ions on air-cleaved mica is important in many interfacial phenomena such as crystal growth, self-assembly and charge transfer on mica. However, due to experimental limitations to nondestructively probe single ions and ionic domains, their exact lateral organization

Effect of Mica and Hematite (001) Surfaces on the Precipitation of Calcite

OpenAIRE

Huifang Xu; Mo Zhou; Yihang Fang; H. Henry Teng

2018-01-01

The substrate effect of mica and hematite on the nucleation and crystallization of calcite was investigated using scanning electron microscope (SEM), X-ray diffraction (XRD), and electron backscatter diffraction (EBSD) methods. On mica, we found, in the absence of Mg2+, the substrates’ (001) surfaces with hexagonal and pseudo-hexagonal two-dimensional (2-D) structure can affect the orientation of calcite nucleation with calcite (001) ~// mica (001) and calcite (010) ~// mica (010) to be the m...

PLACAS CERÂMICAS - UMA INTRODUÇÃO

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Carlos Maurício F. Vieira

2010-05-01

Full Text Available Este trabalho tem por objetivo apresentar uma revisão geral sobre as principais características exigidas para a obtenção de placas cerâmicas (pisos e revestimentos. As principais rotas de processamento são discutidas. Dados de mercado são apresentados com a finalidade de mostrar a importância e a situação atual da indústria cerâmica nacional no setor de pisos e revestimentos.

TICs en la enseñanza de la Química: Propuesta de evaluación de Laboratorios Virtuales de Química (LVQs

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Cataldi, Zulma

2012-01-01

Full Text Available Los LVQs son unas nuevas formas de enseñanza de la química a través del uso de TICs. En este contexto se presenta el relevamiento de los laboratorios virtuales de química (LVQs más apropiados para la enseñanza de la química. Se analizan las ventajas de su aplicación en química básica y se delinean las pautas para su evaluación y selección de acuerdo a los indicadores propuestos, articulados con el marco teórico y con las dimensiones de análisis. Se propone una evaluación centrada en tres ejes: a dimensiones tecnológicas y técnicas, b dimensiones pedagógicas y c otras dimensiones como costo y comercialización. Se realizan pruebas de ajuste y aplicación del instrumento según los siguientes objetivos: a Analizar las estrategias didácticas docentes y la percepción en el uso de las TICs y b Delinear acciones formativas en didáctica de la química con uso de TICs.

Effect of Mica and Hematite (001 Surfaces on the Precipitation of Calcite

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Huifang Xu

2018-01-01

Full Text Available The substrate effect of mica and hematite on the nucleation and crystallization of calcite was investigated using scanning electron microscope (SEM, X-ray diffraction (XRD, and electron backscatter diffraction (EBSD methods. On mica, we found, in the absence of Mg2+, the substrates’ (001 surfaces with hexagonal and pseudo-hexagonal two-dimensional (2-D structure can affect the orientation of calcite nucleation with calcite (001 ~// mica (001 and calcite (010 ~// mica (010 to be the major interfacial relationship. On hematite, we did not observe frequent twinning relationship between adjacent calcite gains, but often saw preferentially nucleation of calcite at surface steps on hematite substrate. We suggest that calcite crystals initially nucleate from the Ca2+ layers adsorbed on the surfaces. The pseudo-hexagonal symmetry on mica (001 surface also leads to the observed calcite (001 twinning. A second and less common orientation between calcite {104} and mica (001 was detected but could be due to local structure damage of the mica surface. Results in the presence of Mg2+ show that the substrate surfaces can weaken Mg toxicity to calcite nucleation and lead to a higher level of Mg incorporation into calcite lattice.

Filogenómica y genómica de la adaptación

OpenAIRE

Zardoya, Rafael; Sánchez-Gracia, Alejandro; Rozas Liras, Julio A.

2017-01-01

La posibilidad técnica actual de secuenciar genomas y transcriptomas completos de cualquier especie abre la puerta a cumplir la predicción de Darwin de poder reconstruir de forma rigurosa el árbol de la vida (las relaciones filogenéticas de todos los seres vivos actuales) mediante la filogenómica.

Relaciones económicas bilaterales entre Ecuador y Brasil

OpenAIRE

Herrera Díaz, Stefany Natalie

2015-01-01

Dentro de la dinámica mundial actual, resulta de especial interés para Ecuador el análisis de sus relaciones económicas bilaterales con Brasil, debido al papel protagónico que ha alcanzado este país tanto a nivel regional como mundial. A nivel regional, varios de los países vecinos han delineado, incluso, su política exterior en función de potenciar sus relaciones políticas y económicas con él, y a nivel internacional, su participación en la geopolítica mundial es cada vez mayor. En términos ...

La argumentación en la formación de profesores de química: relaciones con la comprensión de la historia de la química

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Pablo Antonio Archila

2014-01-01

Full Text Available En este artículo se trata el tema de la argumentación en ciencias de la naturaleza como habilidad de pensamiento y se promueve su inclusión en la formación inicial de profesores de química, pues se reconocen sus potencialidades para la mejora de las comprensiones que los futuros profesores podrían construir acerca de la historia de la química. Para tal fin, se aborda una breve revisión histórica de uno de los hitos de la química, como lo es el desarrollo de la química estructural, con lo cual se sugiere una de las actividades que forman parte de un módulo propuesto para la preparación en argumentación de profesores de química. Finalmente, se discuten algunas reflexiones y perspectivas que resultarían de la articulación entre argumentación e historia de la química.

Synthesis, characterization, and catalytic property of nanosized MgO flakes with different shapes

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yongfen [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Hebei Vocational and Technical College of Building Materials, Qinhuangdao 066004 (China); Ma, Mingzhen, E-mail: mz550509@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Zhang, Xinyu; Wang, Baoan; Liu, Riping [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China)

2014-03-25

Highlights: • MgO nanoflakes with different morphologies were synthesized by a simple low-temperature hydrothermal process. • EDTA and KCl additives have a great effect on the morphology of the products. • Quasi-circular MgO nanoflakes exhibited higher catalytic activity on the thermal decomposition of ammonium perchlorate. -- Abstract: The nanostructures of quasi-circular and hexagonal magnesium oxide (MgO) flakes were successfully prepared by a simple low-temperature hydrothermal reaction. The morphologies were confirmed by field-emission scanning electron microscopy and transmission electron microscopy. Powder X-ray diffraction analysis showed that the nanostructures consisted of cubic-phase MgO. When ethylenediaminetetraacetic acid and potassium chloride were added to the reaction system, the shapes of the synthesized products were found to transform from hexagonal to quasi-circular nanoflakes for different time scales. Fourier-transform infrared spectroscopy indicated numerous hydroxyl radicals on the surface. Quasi-circular magnesia nanoflakes exhibited relatively high catalyst activity for the thermal decomposition of ammonium perchlorate. The mechanism of enhanced catalyst activity was also discussed.

Physical study of the 'snow flake' version of the reactor EL-3 (1963)

International Nuclear Information System (INIS)

Abillon, E.; Genthon, J.P.

1963-01-01

A systematic study has been made of the different thermodynamic and neutronic aspects of various versions of the 'snow flake' likely to fulfil the aims which were set out (improvement of the reactivity, of the experimental volume, improvement in the working conditions of EL-3). After this systematic study, a choice was made in principle of one version amongst the several available (solutions using 8 or 10 pencils-various methods of heat transfer: corrugation, cartridges which may or may not be filled with helium... etc., variable enrichments... ). The choice is that of a version which can already at the present be considered as feasible, which represents already a notable improvement of the pile and which does not imply the existence of a major problem as far as the possible change-over later to an improved version is concerned. This choice defines a fuel element and a configuration for the core. A detailed recapitulation has been made of all the research being carried out for the possible solutions in this particular case. (authors) [fr

Dinámica ambiental y económica en la localidad de Puente Aranda en Bogotá

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Carlos Fernando Parra Moreno

2014-01-01

Full Text Available Este documento muestra los resultados parciales de la investigación “Responsabilidad social y ambiental de la industria manufacturera en la localidad de Puente Aranda en la ciudad de Bogotá como alternativa al desarrollo humano integral sustentable”, realizados dentro del marco de trabajo del grupo de investigación Girsa. El estudio se basó en el análisis de la dinámica poblacional, ambiental y económica de la dicha localidad, a través de la metodología de la matriz de Vester. Con este instrumento se logró identificar las relaciones e interacciones dinámicas de todos los actores locales en el tiempo y en el espacio. Dentro de los problemas críticos que se encontraron en la localidad de Puente Aranda se encontró el agotamiento de fuentes hídricas, poca conciencia y educación ambiental de la población, una mala disposición de basuras, la no disponibilidad de servicios públicos para los nuevos asentamientos y altos niveles de emisión de partículas contaminantes.

Temas de Física para Ingeniería: Primer principio de la termodinámica

OpenAIRE

Beléndez Vázquez, Augusto

1992-01-01

Acústica, fluidos y termodinámica: "Primer principio de la termodinámica". Objetivos y caracteres generales de la termodinámica. Conceptos fundamentales de la termodinámica. Capacidad calorífica, calor específico y calor latente. Trabajo. Primer principio de la termodinámica: energía interna. Algunas aplicaciones del primer principio.

Jackfruit (Artocarpus heterophyllus Lam.) peel: A better source of antioxidants and a-glucosidase inhibitors than pulp, flake and seed, and phytochemical profile by HPLC-QTOF-MS/MS.

Science.gov (United States)

Zhang, Lu; Tu, Zong-Cai; Xie, Xing; Wang, Hui; Wang, Hao; Wang, Zhen-Xing; Sha, Xiao-Mei; Lu, Yu

2017-11-01

Jackfruit (Artocarpus heterophyllus Lam.) peel is an underutilized by-product in both, the production and processing of jackfruit. This research compared the antioxidant and hypoglycemic potential of jackfruit peel with jackfruit pulp, flake and seed for the first time. The phytochemical profile of peel extract was characterized with HPLC-QTOF-MS/MS. Results revealed that peel extract exhibited the highest total phenolic and total flavonoid content, and the phenolics was 4.65, 4.12 and 4.95 times higher than that of pulp, flake and seed extract, respectively. The strongest DPPH and ABTS + scavenging ability, α-glucosidase inhibition were also found in peel extract, and the α-glucosidase inhibition was about 11.8-fold of that of acarbose. The HPLC-QTOF-MS/MS analysis led to the tentative identification of 53 compounds, prenylflavonoids, hydroxycinnamic acids and glycosides are the predominant bioactive compounds. Above results reveal promising potential of jackfruit peel as a new source of natural antioxidants and hypoglycemic agents. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fracture and flaking off behavior of coated layer of DyBCO coated conductor under applied tensile strain

International Nuclear Information System (INIS)

Arai, T.; Shin, J.K.; Matsubayashi, H.; Ochiai, S.; Okuda, H.; Osamura, K.; Prusseit, W.

2009-01-01

The tensile behavior of the DyBa 2 Cu 3 O 7-δ (DyBCO) coated conductor with MgO buffer layer deposited on the Hastelloy C-276 substrate by inclined substrate deposition (ISD) was studied. The tensile stress-strain curve showed a flat region, characterized by the discontinuous yielding of the substrate due to the Lueders band extension from the gripped portions of the sample. In the area where the Lueders band had passed, the coating layer showed severe multiple transverse cracking due to the localized plastic deformation of the substrate. The flaking off of the coating layers took place at high applied strain, due to the buckling fracture of the coated layers in the sample width direction, accompanied by the interfacial debonding.

MICA diversity and linkage disequilibrium with HLA-B alleles in renal-transplant candidates in southern Brazil.

Science.gov (United States)

Yamakawa, Roger Haruki; Saito, Patrícia Keiko; Gelmini, Geórgia Fernanda; da Silva, José Samuel; Bicalho, Maria da Graça; Borelli, Sueli Donizete

2017-01-01

The major histocompatibility complex (MHC) class I chain-related gene A (MICA) is located centromerically to the human leukocyte antigen (HLA)-B. The short distance between these loci in the MHC indicates the presence of linkage disequilibrium (LD). Similarly to the HLA, the MICA is highly polymorphic, and this polymorphism has not been well documented in different populations. In this study, we estimated the allelic frequencies of MICA and the linkage disequilibrium with HLA-B alleles in 346 renal-transplant candidates in southern Brazil. MICA and HLA were typed using the polymerase chain reaction-sequence-specific primer method (PCR-SSO), combined with the Luminex technology. A total of 19 MICA allele groups were identified. The most frequent allele groups were MICA*008 (21.6%), MICA*002 (17.0%) and MICA*004 (14.8%). The most common haplotypes were MICA*009-B*51 (7.8%), MICA*004-B*44 (6.06%) and MICA*002-B*35 (5.63%). As expected from the proximity of the MICA and HLA-B loci, most haplotypes showed strong LD. Renal patients and healthy subjects in the same region of Brazil showed statistically significant differences in their MICA polymorphisms. The MICA*027 allele group was more frequent in renal patients (Pc = 0.018, OR: 3.421, 95% CI: 1.516-7.722), while the MICA*019 allele group was more frequent in healthy subjects (Pc = 0.001, OR: 0.027, 95% CI: 0.002-0.469). This study provided information on the distribution of MICA polymorphisms and linkage disequilibrium with HLA-B alleles in Brazilian renal-transplant candidates. This information should help to determine the mechanisms of susceptibility to different diseases in patients with chronic kidney disease, and to elucidate the mechanisms involved in allograft rejection associated with MICA polymorphisms in a Brazilian population.

Using X-ray photoelectron spectroscopy to discriminate among different sorption sites of micas: With implications for heterogeneous reduction of chromate at the mica-water interface

Energy Technology Data Exchange (ETDEWEB)

Ilton, E.S.; Moses, C.O.; Veblen, D.R.

2000-04-01

This contribution uses Cr2p and 3p binding energies (BEs) determined by X-ray photoelectron spectroscopy (XPS) to distinguish Cr{sup III} sorbed to different mica sorption sites. The results were used to better understand mechanisms for coupled sorption-reduction of Cr{sub (aq)}{sup VI} by ferrous micas. The research is important because: (1) Cr contamination is a serious and wide spread problem associated with a variety of industries; (2) Micas are important sorbents for Cr because they are ubiquitous, sorb cations and anions over a wide range of pH, and participate in heterogeneous redox reactions via structural Fe{sup II} and FE{sup III}; and (3) The mobility of cations sorbed by micas will depend, in part, on the dominant sorption site. Micas (two biotites, end member phologopite and muscovite) were reacted with Cr{sup III} solutions that contained variable concentrations of NaCl and KCl. Samples were extracted at times intervals and mica edge orientations were analyzed by ZPS. Cr{sub (aq)}{sup III} sorption was greater in Cr{sup III}-NaCl solutions relative to Cr{sup III}-KCl solutions. Cr2p and 3p BEs were bracketed by those for Cr{sup III} in the structure of silicates and in Cr{sup III}-oxyhydroxides. The BE of Cr{sup III} sorbed to micas was higher by about 0.3 eV after reaction with Cr{sup III}-NaCl solutions compared to Cr{sup III}-KCl aqueous solutions. At the experimental conditions, Na{sup +} and K{sup +} differentially block permanent charge sites but not variably charged edge sites of micas. Using the constraints inherent in the experimental design, the authors interpret the difference in CR{sup III} BE between the Cr{sup III}-NaCl and Cr{sup III}-KCl experiments to reflect a change in the dominant sorption site, where high and low Cr BEs indicate Cr sorbed by the interlamellar region and variably charged functional groups at mica edges, respectively. They conclude that small BE shifts for cations sorbed to silicates can be interpreted with

Alfabetización económica y actitudes hacia la compra en universitarios posterior a un programa de educación económica

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Marianela Denegri Coria

2016-01-01

después de participar en el programa de Educación Económica se les aplicó la Escala de Actitudes hacia la Compra y el Consumo y el Test de Alfabetización Económica para adultos (TAE-A. Los resultados indican una menor tendencia hacia la impulsividad en la compra y el consumo en los estudiantes después de participar en la intervención. Las implicancias de este estudio enfatizan la necesidad de crear tempranamente programas de formación económica para favorecer el cambio actitudinal y el consumo reflexivo.

Experiencias divertidas de electroquímica casera

OpenAIRE

Santiago Heredia-Avalos

2007-01-01

La química, dentro de la cual se incluye la electroquímica, es una materia que los estudiantes suelen ver como complicada, aburrida, carente de interés y que, además requiere de material de laboratorio sofisticado y reactivos químicos inaccesibles. Nada más lejos de la realidad, tal y como se pondrá de manifiesto en este trabajo, donde se proponen varias experiencias sencillas usando sustancias baratas, la mayoría de las cuales pueden encontrarse en un supermercado, y utensilio...

Scrophulariaceae endémicas del Perú

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Blanca León

2013-10-01

Full Text Available La familia Scrophulariaceae es reconocida en el Perú por presentar alrededor de 18 géneros y 35 especies (Brako & Zarucchi, 1993; Ulloa Ulloa et al., 2004, principalmente herbáceas. En este trabajo reconocemos dos especies endémicas en dos géneros, las cuales se encuentran principalmente en la región Bosques Húmedos Amazónicos, entre los 200 y 1000 m de altitud. Ninguna de las especies endémicas se encuentra representada dentro del Sistema Nacional de Áreas Naturales Protegidas por el Estado.

Oleaceae endémicas del Perú

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Isidoro Sánchez

2013-10-01

Full Text Available La familia Oleaceae es reconocida en el Perú por presentar seis géneros y 13 especies (Brako & Zarucchi, 1993, la mayoría árboles. En este trabajo reconocemos dos especies endémicas en igual número de géneros. Las especies endémicas han sido encontradas en las regiones Matorral Desértico y Bosques Húmedos Amazónicos, entre los 250 y 1850 m de altitud. Ambas especies se encuentran dentro del Sistema Nacional de Áreas Naturales Protegidas por el Estado.

El Área de Ciencia y Tecnologías Químicas del CSIC: ¿Un Área de químicas?

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García-López, María Teresa

2002-08-01

Full Text Available Not available

El artículo titulado "El Area de Ciencia y Tecnologías Químicas del CSIC: ¿un Area de químicas?» pretende mostrar una breve panorámica del lugar que ocupa el género femenino dentro de la citada Area. En la primera parte se aportan las estadísticas que reflejan el número y porcentaje de científicas totales en los distintos Institutos del Area, así como su distribución entre las tres escalas de personal científico del Organismo. Una segunda parte está dedicada a recoger las aportaciones personales de varias científicas del Area acerca del tema, visto desde sus propias experiencias.

Dinámicas de la actividad científica del Instituto de Investigaciones Socio-Económicas de la Universidad Nacional de San Juan de Argentina

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Gonzalo Miguel Castillo

2018-02-01

Full Text Available Este artículo fue un estudio de caso en torno a las capacidades de investigación generadas en el Instituto de Investigaciones Socio-Económicas de la Facultad de Ciencias Sociales, perteneciente a la Universidad Nacional de San Juan, en Argentina. Aborda los principales acontecimientos históricos de la institución y su dinámica actual, tuvo en cuenta las áreas de conocimiento en las cuales se desarrollan sus investigaciones. A su vez, este trabajo ha descrito las dinámicas de la revista académica producida en este instituto, denominada REVIISE. La metodología fue un abordaje objetivo/descriptivo. Se procedió a analizar el papel, devenir y accionar del IISE y las modalidades de proyectos de investigación ejecutados. Fueron indagados el funcionamiento de la REVIISE, identificando perfiles académicos de sus autores, circuitos de difusión y redes académicas; y la conformación de comités y consejos editoriales y académicos que componen esta publicación. Se propone realizar un recorrido que atraviesa lo institucional, los agentes académicos y la principal red de difusión de la producción de conocimiento para comprender las capacidades investigativas del Instituto de Investigaciones Socio Económicas.

Morphology and thermal degradation study of poly(lactic acid)/synthetic mica composites

International Nuclear Information System (INIS)

Souza, D.H.S.; Dias, M.L.

2010-01-01

Poly(lactic acid) (PLA)/synthetic mica composites has been little studied in the literature. In this work, an organophilic synthetic mica was used to prepare PLA nanocomposites. The composites were obtained at an internal mixer containing 3, 5, 7 and 10 wt% of mica. The materials were analyzed by x-ray diffraction, thermogravimetric analysis and gel permeation chromatography. (author)

Mössbauer spectra of white micas from the Central Western Carpathians Mountains

Science.gov (United States)

Sitek, J.; Sulák, M.; Putiš, M.; Tóth, I.

2010-03-01

Potassium white micas from the rocks included into Cretaceous deformation zones (ca. 100-70 Ma in age) of the Central Western Carpathians were investigated by Mössbauer spectroscopy. White micas formed during a polystage evolution and changing P-T conditions of their crystallization in crustal-scale shear zones. We found criteria for distinguishing generations of celadonite-poor (muscovitic) and celadonite-rich (phengitic) white micas using Mössbauer spectroscopy. This method revealed contrasting spectra characterized by typical quadrupole doublets corresponding to Fe2+ Fe3+ contents in white micas. They are in the range of 2.9-3.0 mm/s for phengite, and 2.6-2.7 mm/s for muscovite. Mössbauer spectra reflect well the chemical changes in white mica aggregates, especially of those close to the end-member muscovite and (alumino-)celadonite compositions.

Clinical relevance of pre and post-transplant immune markers in kidney allograft recipients: anti-HLA and MICA antibodies and serum levels of sCD30 and sMICA.

Science.gov (United States)

Solgi, Ghasem; Furst, Daniel; Mytilineos, Joannis; Pourmand, Gholamreza; Amirzargar, Ali Akbar

2012-03-01

This retrospective study aims to determine the prognostic values of HLA and MICA antibodies, serum levels of sCD30 and soluble form of MHC class I related chain A (sMICA) in kidney allograft recipients. Sera samples of 40 living unrelated donor kidney recipients were tested by ELISA and Flow beads techniques for the presence of anti HLA and MICA antibodies and the contents of sCD30 and sMICA. HLA and MICA antibody specification was performed by LABScreen single antigen beads to determine whether the antibodies were directed against donor mismatches. Within first year post operatively 9 of 40 patients (22.5%) showed acute rejection episodes (ARE) that four of them lost their grafts compared to 31 functioning transplants (P=0.001). The presence of HLA antibodies before and after transplantation was significantly associated with ARE (P=0.01 and P=0.02 respectively). Sensitization to HLA class II antigens pre-transplant was strongly associated with higher incidence of ARE (P=0.004). A significant correlation was found between ARE and appearance of non-donor specific antibodies (P=0.02). HLA antibody positive patients either before or after transplantation showed lower graft survival rates than those without antibodies during three years follow-up (P=0.04 and P=0.02). Anti-MICA antibodies were observed in 8/40(20%) and 5/40(12.5%) of patients pre and post-transplant respectively. Coexistence of HLA and MICA antibodies was shown in 2 of 4 cases with graft loss. A significant increased level of sCD30 at day 14 (P=0.001) and insignificant decreased levels of sMICA pre and post operatively were detected in rejecting transplants compared to functioning graft group. Our findings support the view that monitoring of HLA and MICA antibodies as well as sCD30 levels early after transplant has predictive value for early and late allograft dysfunctions and the presence of these factors are detrimental to graft function and survival. Copyright © 2012 Elsevier B.V. All rights

AVALIAÇÃO FÍSICA, QUÍMICA, BIOQUÍMICA E AGRONÔMICA DE CULTIVARES DE FEIJÃO-GUANDU (CAJANUS CAJAN (L MILL

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SOLANGE GUIDOLIM CANNIATTI-BRAZACA

2009-07-01

Full Text Available

RESUMO: Foram estudadas as características físicas, químicas, bioquímicas e agronômicas de 40 cultivares de feijão-guandu (Cajanus cajan (L Mill provenientes da EMBRAPA de São Carlos (SP e originárias de diversas regiões do Brasil e da Índia. Pode-se observar entre os cultivares variações expressivas no tempo de cocção, no teor de lectinas e na produtividade. Os resultados obtidos quanto ao teor protéico e à digestibilidade do guandu, quando comparadas com os resultados obtidos na literatura, mostraram-se semelhantes aos dos grãos de feijão-comum. Pode-se, também, observar baixos teores de taninos entre os cultivares estudados. Foram selecionados três cultivares por apresentarem melhores características entre os parâmetros estudados. PALAVRAS-CHAVE: Feijão-guandu; proteínas; fatores antinutricionais; produtividade.

O uso de técnica eletroquímica para a descontaminação de estruturas cerâmicas vítreas porosas

OpenAIRE

Assis,O. B. G.; Silva,E. R.

2010-01-01

Apresentamos neste trabalho os resultados de ensaios preliminares para avaliar o uso de técnica de eletro-osmose para a remoção de contaminantes orgânicos em estruturas porosas cerâmicas, como filtros ou similares. A técnica consiste em forçar a migração de contaminantes retidos na estrutura interna ou na superfície dos poros por meio da aplicação de tensão controlada em célula eletroquímica projetada para este fim. As moléculas absorvidas na superfície cerâmica estarão sujeitas as ações cisa...

Actitudes y rendimiento académico: su evolución desde química general e inorgánica hasta química orgánica

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María S. Reyes

2014-01-01

Full Text Available Esta investigación tiene un doble propósito, en primer lugar, valorar las actitudes hacia la química de alumnos universitarios de carreras biológicas en dos cursos relacionados con esta disciplina y, por otro lado, relacionar dichas actitudes con el rendimiento académico presentado por los estudiantes. El instrumento elegido para medir las actitudes de los alumnos fue un cuestionario según la escala Likert, encuestándose a la totalidad de estudiantes que cursaban cada uno de los cursos de química analizados: Química General e Inorgánica (QGI y Química Orgánica (QO. Para estimar el rendimiento académico se analizaron actas de parciales y se realizaron cálculos de correlación. Los alumnos que cursaban QGI presentaron actitudes hacia la química valoradas como indiferentes. Sin embargo al finalizar el curso de QO sus actitudes fueron evolucionando favorablemente, ya que la puntuación media obtenida para los ítems positivos y negativos estuvo en el rango de actitudes positivas. Los valores del coeficiente de Pearson obtenidos para los dos cursos estudiados fueron superiores a 0,80, lo que indica una fuerte relación entre las variables implicadas, por lo cual se infiere la importancia de desarrollar actitudes positivas hacia la química para favorecer el rendimiento académico de los alumnos.

Transparent Indium Tin Oxide Electrodes on Muscovite Mica for High-Temperature-Processed Flexible Optoelectronic Devices.

Science.gov (United States)

Ke, Shanming; Chen, Chang; Fu, Nianqing; Zhou, Hua; Ye, Mao; Lin, Peng; Yuan, Wenxiang; Zeng, Xierong; Chen, Lang; Huang, Haitao

2016-10-26

Sn-doped In 2 O 3 (ITO) electrodes were deposited on transparent and flexible muscovite mica. The use of mica substrate makes a high-temperature annealing process (up to 500 °C) possible. ITO/mica retains its low electric resistivity even after continuous bending of 1000 times on account of the unique layered structure of mica. When used as a transparent flexible heater, ITO/mica shows an extremely fast ramping (solar cells (PSCs) with high efficiency.

Dinamizando el proceso de enseñanzaaprendizaje de la química. Las demostraciones químicas como una opción para cambiar la forma tradicional de enseñar química

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Manuel Molina Caballero

2009-10-01

Full Text Available Creemos que la “quimifobia” que existe a nivel social está generada en buena medida por la forma cómo se realiza la enseñanza de la química en las aulas. Para generar un cambio en las metodologías habituales proponemos, en este trabajo, el uso de las demostraciones químicas, mostrando un ejemplo a partir de la descomposición del peróxido de hidrógeno, buscando la forma de incorporar las demostraciones en el aula y considerando su carácter atractivo, la participación del estudiante, su vínculo conceptual y las cuestiones de seguridad a tener en cuenta. Dejamos a los profesores la propuesta, esperando que con su ayuda quizá podamos dar un toque especial a la enseñanza de la química.

Electronic structure and field emission properties of nitrogen doped graphene nano-flakes (GNFs:N) and carbon nanotubes (CNTs:N)

Energy Technology Data Exchange (ETDEWEB)

Ray, Sekhar C., E-mail: Raysc@unisa.ac.za [Department of Physics, College of Science, Engineering and Technology, University of South Africa, Private Bag X6, Florida, 1710, Science Campus, Christiaan de Wet and Pioneer Avenue, Florida Park, Johannesburg (South Africa); Pong, W.F. [Department of Physics, Tamkang University, Tamsui 251, New Taipei City, Taiwan (China); Papakonstantinou, P. [Nanotechnology and Integrated Bio-Engineering Centre, University of Ulster, Shore Road, Newtownabbey BT37 0QB (United Kingdom)

2016-09-01

Highlights: • Nitrogen doped graphene nano-flakes (GNFs:N) and carbon nano-tubes (CNTs:N) are used to study the electronic/bonding structure along with their defects state. • The I{sub D}/I{sub G} ratio obtained from Raman spectroscopy used for the study of the defects states of CNTs:N than GNFs:N. • The electron field emission result shows that the turn on electric field is lower in case of CNTs:N than GNFs:N. • All results are good agreement with XANES and the results obtained from Raman spectra. - Abstract: Substitution of hetero-atom doping is a promising route to modulate the outstanding material properties of carbon nanotubes and graphene for customized applications. Nitrogen-doping has been introduced to ensure tunable work-function, enhanced n-type carrier concentration, diminished surface energy, and manageable polarization. Along with the promising assessment of N-doping effects, research on the N-doped carbon based composite structures is emerging for the synergistic integration with various functional materials. Nitrogen undoped/doped graphene nano-flakes (GNFs/GNFs:N) and multiwall carbon nano-tubes (MWCNTs/MWCNTs:N) are used for comparative study of their electronic/bonding structure along with their defects state. X-ray absorption near edge structure (XANES) spectroscopy shows that the GNFs:N produce mainly pyridine like structure; whereas MWCNTs:N shows graphitic nitrogen atoms are attached with the carbon lattice. The I{sub D}/I{sub G} ratio obtained from Raman spectroscopy shows that the defects is higher in MWCNTs:N than GNFs:N. The electron field emission result shows that the turn on electric field is lower (higher electron emission current) in case of MWCNTs:N than GNFs:N and are good agreement with XANES and the results obtained from Raman spectra.

La imagen pública de la química y su relación con la generación de actitudes hacia la química y su aprendizaje

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William Manuel Mora Penagos

2012-04-01

Full Text Available El presente ensayo muestra cómo la imagen popular y escolar de la química se caracteriza por ser negativa, lo que viene incidiendo en la generación de actitudes negativas hacia esta ciencia y su aprendizaje. Las inadecuadas formas de comunicación del conocimiento de la química que se muestran en el cine, la TV y las revistas de ciencia popular, la visión irreconciliable entre ciencia y religión, y la poca claridad de las formas de producción del conocimiento químico mostradas en las aulas de clase, aparecen como las principales causas de esta situación. Superar esta imagen implica reconciliar la visión científica con la visión social de la química, por lo que el conocimiento en epistemología e historia de la química y la línea de investigación conocida como Public Understanding of Science desde el enfoque Ciencia/Tecnología/ Sociedad y Ambiente (CTS-A, son fundamentales para una didáctica de la química orientada hacia la alfabetización en química y a la formación docentes en torno al diseño curricular y la enseñanza de contenidos articulados a la generación de actitudes hacia el impacto social y ambiental de la química.

Determining lake surface water temperatures worldwide using a tuned one-dimensional lake model (FLake, v1)

Science.gov (United States)

Layden, Aisling; MacCallum, Stuart N.; Merchant, Christopher J.

2016-06-01

A tuning method for FLake, a one-dimensional (1-D) freshwater lake model, is applied for the individual tuning of 244 globally distributed large lakes using observed lake surface water temperatures (LSWTs) derived from along-track scanning radiometers (ATSRs). The model, which was tuned using only three lake properties (lake depth, snow and ice albedo and light extinction coefficient), substantially improves the measured mean differences in various features of the LSWT annual cycle, including the LSWTs of saline and high altitude lakes, when compared to the observed LSWTs. Lakes whose lake-mean LSWT persists below 1 °C for part of the annual cycle are considered to be seasonally ice-covered. For trial seasonally ice-covered lakes (21 lakes), the daily mean and standard deviation (2σ) of absolute differences between the modelled and observed LSWTs are reduced from 3.07 °C ± 2.25 °C to 0.84 °C ± 0.51 °C by tuning the model. For all other trial lakes (14 non-ice-covered lakes), the improvement is from 3.55 °C ± 3.20 °C to 0.96 °C ± 0.63 °C. The post tuning results for the 35 trial lakes (21 seasonally ice-covered lakes and 14 non-ice-covered lakes) are highly representative of the post-tuning results of the 244 lakes. For the 21 seasonally ice-covered lakes, the modelled response of the summer LSWTs to changes in snow and ice albedo is found to be statistically related to lake depth and latitude, which together explain 0.50 (R2adj, p = 0.001) of the inter-lake variance in summer LSWTs. Lake depth alone explains 0.35 (p = 0.003) of the variance. Lake characteristic information (snow and ice albedo and light extinction coefficient) is not available for many lakes. The approach taken to tune the model, bypasses the need to acquire detailed lake characteristic values. Furthermore, the tuned values for lake depth, snow and ice albedo and light extinction coefficient for the 244 lakes provide some guidance on improving FLake LSWT modelling.

Cuscutaceae endémicas del Perú

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Blanca León

2013-10-01

Full Text Available La familia Cuscutaceae es reconocida en el Perú por presentar un género, Cuscuta, y 19 especies (Brako & Zarucchi, 1993, todas ellas hierbas. En este trabajo reconocemos siete especies endémicas, aunque en necesidad de revisión taxonómica y colecciones botánicas; por ello no se aplicaron las categorías y criterios de la UICN. Estos taxones endémicos ocupan principalmente la región Mesoandina, por debajo de los 3200 m de altitud. Aparentemente, sólo una de estas especies se encuentra representada dentro del Sistema Nacional de Áreas Naturales Protegidas por el Estado.

Dilleniaceae endémicas del Perú

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Blanca León

2013-10-01

Full Text Available La familia Dilleniaceae es una adición reciente a la flora endémica peruana; los endemismos han sido recolectados y reconocidos hacia fines de los 1990. Está representada en el Perú por seis géneros y 23 especies (Brako & Zarucchi, 1993; Ulloa Ulloa et al., 2004, la mayoría lianas. En este trabajo reconocemos tres endemismos en dos géneros. Las especies endémicas ocupan la región Bosques Húmedos Amazónicos, entre los 100 y 125 m de altitud. No se encuentra representada en el Sistema Nacional de Áreas Naturales Protegidas por el Estado.

Las cooperativas: Una alternativa económica y social frente a la crisis

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Javier Divar Garteiz-Aurrecoa

2013-12-01

Full Text Available El Cooperativismo nació como alternativa económica y social, impulsado por la piedad religiosa y reglado bajo los principios democráticos. La solidaridad y la democracia económica hacen de las cooperativas  sociedades especialmente resistentes frente a las dificultades económicas.Recibido: 29.05.2013Aceptado: 26.06.2013

Polycrystalline Nd2Fe14B/α-Fe nanocomposite flakes with a sub-micro/nanometre thickness prepared by surfactant-assisted high-energy ball milling

International Nuclear Information System (INIS)

Tang, Xin; Chen, Xi; Chen, Renjie; Yan, Aru

2015-01-01

Highlights: • Nd 2 Fe 14 B/α-Fe flakes are formed by peeling along preferential planes. • (0 0 l) planes are found to be preferential cleavage planes. • Magnetic properties degrade with increasing ball milling time. • Anisotropic nanocomposite magnets are fabricated. - Abstract: A surfactant-assisted high-energy ball milling technique was employed to synthesize Nd 2 Fe 14 B/α-Fe nanoparticles and nanoflakes from melt-spun nanocrystalline powders. The microstructure evolution in ball milling process was investigated. In the beginning stage (0–4 h) of ball milling, raw powders were crushed into micrometre-sized particles. While flakes were mainly formed by reducing thickness of particles via peeling layer by layer along preferential planes in the late stage (8–16 h). The selected area electron diffraction and high-resolution transmission electron microscopy images show that preferential cleavage planes are basal planes. With ball milling proceeding, more and more defects were induced by ball milling. As a result, the coercivity and remanence decreased to 1.6 kOe and 3.2 kGs, respectively. After 16 h ball milling, the exchange decoupling occurred due to severe amorphorization. A weakly-textured nanocomposite magnet was fabricated after 12 h ball milling and the anisotropy in magnetic properties can be further improved by employing settling down process to select particle size and aligning particles in external field

Principios de laboratorio y aplicaciones en la práctica clínica de las técnicas moleculares, genómicas y proteómicas

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Jenny Hernández Betancourt

2014-10-01

Full Text Available La heterogénea expresión clínica de las enfermedades, la necesidad de la interpretación de los procesos fisiológicos y fisiopatológicos, así como la búsqueda incesante de nuevas estrategias diagnósticas y terapéuticas, han conducido al desarrollo de las biociencias, en particular de la genética, la genómica, la biología molecular y las tecnologías asociadas. Han emergido en los últimos años disciplinas como la trascriptómica, la epigenómica, la proteómica y la metabolómica, cada una con un objeto de estudio determinado, que deriva de los tipos moleculares específicos y sus relaciones y todas con aplicaciones potenciales dentro de una nueva medicina con un enfoque personalizado. Hoy se dispone de técnicas moleculares que se basan en la hibridación de ácidos nucleicos, tanto in situ como el dot-blot, el Southern blot y el Northern blot. Otros métodos requieren la amplificación del ADN, como la reacción en cadena de la polimerasa, los microarreglos y la secuenciación. La proteómica se perfila como una potente herramienta para el estudio de aspectos fisiológicos y patológicos del ser humano; sus técnicas incluyen la electroforesis bidimensional, la espectrometría de masas y las micromatrices de proteínas. La búsqueda activa de biomarcadores a partir de casi todos los líquidos biológicos y tejidos de varias naturalezas es una de las principales aplicaciones de la proteómica. Es importante atender, comprender e introducir estos nuevos métodos en la práctica clínica por sus potencialidades para el diagnóstico, el desarrollo de estrategias terapéuticas, la predicción y estratificación de riesgo, de la resistencia al tratamiento y las posibilidades de supervivencia

Funciones Económicas en un Entorno Incierto

OpenAIRE

Lazzari, Luisa L; Chiodi, Jorge A; Moulia, Patricia I

2015-01-01

El mundo está atravesando una de las crisis económicas más profundas de los últimos tiempos. Los escenarios actuales y futuros están plagados de incertidumbre que, en general, no se considera en el análisis de las distintas funciones económicas de interés para el desarrollo del negocio, y la realidad se representa mediante modelos estáticos y casi perfectos del comportamiento de los mercados. La teoría de conjuntos borrosos permite construir modelos adecuados a partir de realidades inciertas ...

CD56+ immune cell infiltration and MICA are decreased in breast lobules with fibrocystic changes.

Science.gov (United States)

Kerekes, Daniel; Visscher, Daniel W; Hoskin, Tanya L; Radisky, Derek C; Brahmbhatt, Rushin D; Pena, Alvaro; Frost, Marlene H; Arshad, Muhammad; Stallings-Mann, Melody; Winham, Stacey J; Murphy, Linda; Denison, Lori; Carter, Jodi M; Knutson, Keith L; Degnim, Amy C

2018-02-01

While the role of natural killer (NK) cells in breast cancer therapy has been investigated, little information is known about NK cell function and presence in nonmalignant and premalignant breast tissue. Here, we investigate and quantify NK cell marker CD56 and activating ligand MICA in breast tissue with benign breast disease. Serial tissue sections from 88 subjects, 44 with benign breast disease (BBD) who remained cancer-free, and 44 with BBD who later developed cancer, were stained with H&E, anti-MICA, and anti-CD56. Up to ten representative lobules were identified on each section. Using digital image analysis, MICA and CD56 densities were determined for each lobule, reported as percent of pixels in the lobule that registered as stained by each antibody. Analyses were performed on a per-subject and per-lobule basis. Per-subject multivariate analyses showed associations of CD56 and MICA with age: CD56 was increased in older subjects (p = 0.03), while MICA was increased in younger subjects (p = 0.005). Per-lobule analyses showed that CD56 and MICA levels were both decreased in lobules with fibrocystic change, with median levels of CD56 and MICA staining, respectively, at 0.31 and 7.0% in fibrocystic lobules compared to 0.76 and 12.2% in lobules without fibrocystic change (p fibrocystic lobules, proliferative/atypical lobules showed significantly lower expression compared to nonproliferative lobules for MICA (p = 0.02) but not for CD56 (p = 0.80). Levels of CD56+ NK cells and activating ligand MICA were decreased in breast lobules with fibrocystic change, and MICA levels showed a significant stepwise decrease with increasing histopathologic abnormality. MICA levels were also significantly decreased in older subjects, who generally have higher risk of developing cancer. These findings advance a model in which MICA promotes cytotoxic activity in CD56+ NK cells to protect against tumorigenesis in breast lobules, and suggest further research is warranted.

Influencia de la autoeficacia académica y la procrastinación académica sobre el cansancio emocional de estudiantes de la Universidad Alas Peruanas, Lima, 2015

OpenAIRE

Gutiérrez Torres, Andrés Martín

2015-01-01

Objetivo: determinar cuánta es la influencia de la autoeficacia académica y la procrastinación académica sobre el cansancio emocional de estudiantes de la Universidad Alas Peruanas, Lima, 2015. Metodología: se usó un diseño observacional, transversal, retrospectivo y correlacional-causal. La muestra no probabilística fue de 332 estudiantes de Psicología de una universidad privada de Lima, quienes fueron evaluados con tres instrumentos: Escala de Autoeficacia para Situaciones Académicas, E...

Loranthaceae endémicas del Perú

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Blanca León

2013-10-01

Full Text Available La familia Loranthaceae está representada en la flora peruana por 11 géneros y 63 especies (Brako & Zarucchi, 1993; Ulloa Ulloa et al., 2004, la mayoría arbustos. En este trabajo se reconoce 14 especies endémicas en cinco géneros. Los endemismos en esta familia ocupan diversas regiones, como la Mesoandina, Puna Húmeda y Seca y Bosques Muy Húmedos Montanos, desde los 1400 hasta los 4200 m de altitud. Se aplicaron las categorías y criterios de la UICN a 11 especies. Cinco especies endémicas se encuentran representadas en del Sistema Nacional de Áreas Naturales Protegidas por el Estado.

Crassulaceae endémicas del Perú

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Blanca León

2013-10-01

Full Text Available La familia Crassulaceae es reconocida en el Perú por presentar cinco géneros y 29 especies (Brako & Zarucchi, 1993, mayormente arbustos y hierbas. En este trabajo reconocemos 13 especies y dos variedades como endemismos peruanos en tres géneros. Echeveria es el género con el mayor número de especies endémicas. Los taxones endémicos ocupan principalmente las regiones Mesoandina y Puna Húmeda y Seca, entre los 1700 y 4500 m de altitud. Se aplicaron las categorías y criterios de la UICN a nueve taxones. Dos Crassulaceae endémicas están representados dentro del Sistema Nacional de Áreas Naturales Protegidas por el Estado.

Optimal PMU location in power systems using MICA

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Seyed Abbas Taher

2016-03-01

Full Text Available This study presented a modified imperialist competitive algorithm (MICA for optimal placement of phasor measurement units (PMUs in normal and contingency conditions of power systems. The optimal PMU placement problem is used for full network observability with the minimum number of PMUs. For this purpose, PMUs are installed in strategic buses. Efficiency of the proposed method is shown by the simulation results of IEEE 14, 30, 57, and 118-bus test systems. Results of the numerical simulation on IEEE-test systems indicated that the proposed technique provided maximum redundancy measurement and minimum request of PMUs so that the whole system could be topologically observable by installing PMUs on the minimum system buses. To verify the proposed method, the results are compared with those of some recently reported methods. When MICA is used for solving optimal PMU placement (OPP, the number of PMUs would be usually equal to or less than those of the other existing methods. Results indicated that MICA is a very fast and accurate algorithm for OPP solution.

Computadores y democracia económica

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Allin Cottrell

2008-12-01

Full Text Available El colapso del socialismo anteriormente existente obedeció a causas integradas en su mecanismo económico, que no son inherentes a todos los socialismos posibles. El artículo muestra que la teoría económica marxista, junto con la informática, proporciona el fundamento para adelantar un programa económico socialista viable y que el desarrollo de la informática y de Internet hace posible la planificación económica. Además, argumenta que el movimiento socialista nunca desarrolló un programa constitucional correcto y que la tecnología moderna abre nuevas oportunidades para la democracia. Por último, revisa los argumentos austriacos contra la posibilidad del cálculo socialista a la luz de la nueva capacidad informática y de las limitaciones del Protocolo de Kyoto.

Farmacogenómica

OpenAIRE

Izaguirre Pasquel, Victor

2014-01-01

La farmacogenómica, área de investigación innovadora y de reciente desarrollo, surge para explicar las diferencias interindividuales en la respuesta a los fármacos y evitar reacciones adversas y costes innecesarios. Básicamente, esta nueva ciencia tiene dos orientaciones, una centrada en el diseño de fármacos para el tratamiento de una enfermedad que tiene un marcado carácter genético y otra, en el diseño de fármacos con menor toxicidad para pacientes con deficiencias y/o alteraciones génicas...

The role of herbometallic preparations in traditional medicine--a review on mica drug processing and pharmaceutical applications.

Science.gov (United States)

Wijenayake, Apsara; Pitawala, Amarasooriya; Bandara, Ratnayake; Abayasekara, Charmalie

2014-09-11

Biotite mica enriched with Fe(2+) ions are widely used as a major mineral ingredient in traditional pharmaceutical science of alchemy (Rasashastra). Abhrak bhasma (mica ash), a pharmaceutical product containing treated mica, is utilized, for example, in Ayurvedic treatments for ailments such as gastritis, renal disease, skin disease and mainly in rejuvenation formulations. However, the untreated mica minerals may be harmful when used directly, as they carry considerably high amounts of trace-elements that can cause undesirable effects in the human body. In order to remove toxic factors and produce readily absorbable materials having high nutrient capacity, specific thermal and chemical treatments (purification, detoxification, particle size reduction and incineration) are performed during the preparation of Rasashastra. This review evaluates the chemical and pharmacological aspects of mica ash as well as the technological aspects of mica ash production. The detailed literature review on the chemistry and scientific basis of mica ash, its preparation techniques, mica alterations and pharmaceutical applications was carried out by using published Ayurvedic text books and research articles, available from Science Direct, on mica minerals, mica ash and their physico-chemical alteration processes and pharmacological applications. During the purification and detoxification procedures, heating followed by quenching (in ionic medium) influences the structural distortion and the development of stress-induced cracks and spallations of the micaceous plates. Thus, the efficient diffusion of the external medium takes place at successive heating and quenching steps. Acidic organic liquids and animal byproducts can enhance the cation exchange capacity and solubility of mica. Further, these natural compounds facilitate the removal of toxic-elements in the structure. When treated-mica and paddy husks are tied up in a cloth and squeezed, particle size reduction and further

Molecular dynamics study of room temperature ionic liquids with water at mica surface

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Huanhuan Zhang

2018-04-01

Full Text Available Water in room temperature ionic liquids (RTILs could impose significant effects on their interfacial properties at a charged surface. Although the interfaces between RTILs and mica surfaces exhibit rich microstructure, the influence of water content on such interfaces is little understood, in particular, considering the fact that RTILs are always associated with water due to their hygroscopicity. In this work, we studied how different types of RTILs and different amounts of water molecules affect the RTIL-mica interfaces, especially the water distribution at mica surfaces, using molecular dynamics (MD simulation. MD results showed that (1 there is more water and a thicker water layer adsorbed on the mica surface as the water content increases, and correspondingly the average location of K+ ions is farther from mica surface; (2 more water accumulated at the interface with the hydrophobic [Emim][TFSI] than in case of the hydrophilic [Emim][BF4] due to the respective RTIL hydrophobicity and ion size. A similar trend was also observed in the hydrogen bonds formed between water molecules. Moreover, the 2D number density map of adsorbed water revealed that the high-density areas of water seem to be related to K+ ions and silicon/aluminum atoms on mica surface. These results are of great importance to understand the effects of hydrophobicity/hydrophicility of RTIL and water on the interfacial microstructure at electrified surfaces. Keywords: Room temperature ionic liquids, Hydrophobicity/hydrophicility, Water content, Electrical double layer, Mica surface

MeV fullerene impacts on mica

Energy Technology Data Exchange (ETDEWEB)

Doebeli, M.; Scandella, L. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Ames, F. [Eidgenoessische Technische Hochschule, Zurich (Switzerland)

1997-09-01

Hillock heights on mica irradiated with MeV C{sub 60} ions have been investigated systematically. Results show that the small range of secondary particles along the track plays a crucial role in defect production. (author) figs., tab., refs.

La elite económica Argentina, 1810-1914

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Roy Hora

2014-12-01

Full Text Available Este artículo analiza los principales rasgos del sector más poderoso de la elite económica argentina del período 1810-1914. El trabajo discute las principales interpretaciones sobre las características y naturaleza de este grupo, pone de relieve algunas de limitaciones de los enfoques más habituales sobre el tema, y sugiere de qué manera conceptualizarlo de forma productiva. Aunque el objeto de este trabajo es la elite económica, todo análisis de este actor supone a la vez una manera de concebir las características del sistema de poder y del entorno económico en el que se desenvuelve la acción de los hombres de fortuna. Por este motivo, este trabajo formula algunas consideraciones generales sobre las características del Estado (argentino y el capitalismo (pampeano, con el fin de precisar mejor qué tipo de elite económica dominó la producción rural y la economía argentina en el período de crecimiento exportador que se extendió desde la Independencia hasta la Primera Guerra Mundial. El trabajo toma distancia de los estudios que enfatizan la importancia de la dimensión política para explicar el proceso de constitución y reproducción de esta elite económica, enfatizando en cambio los determinantes económicos de este proceso. El ensayo no aporta nueva evidencia empírica, sino una reflexión a partir de la literatura existente.

The nanostructure formation on muscovite mica surface induced by intermediate-energy ions

Energy Technology Data Exchange (ETDEWEB)

Zhou, P.; Zhang, HQ., E-mail: zhanghq@lzu.edu.cn; Zhang, Q.; Liu, Z.; Guan, S.; Wang, G.; Zhou, C.; Jia, J.; Lv, X.; Shao, J.; Cui, Y.; Chen, L.; Chen, X., E-mail: chenxm@lzu.edu.cn

2013-07-15

Muscovite mica sheets were bombarded by lithium, carbon and oxygen ions in the energy range from several hundred keV to several MeV. The induced surface structures were measured in the air with atomic force microscopy (AFM) in the tapping mode. The hillock-like structure on the mica surface was observed. The height of the hillock increases linearly when the energy loss is above 1.2 keV/nm. The induced structures are similar with the similar electronic stopping powers but different projectiles for muscovite mica.

El Derecho de Competencia Económica en la Constitución del Ecuador

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Marcelo Marín Sevilla

2011-12-01

Full Text Available Este trabajo permite establecer las bases de la Constitución Económica y del Derecho de Competencia Constitucionalizado.  También analiza si las normas de Derecho de la Competencia Económica y su doctrina están acorde y son adecuadas frente a la Constitución del Ecuador. El Derecho de la Competencia Económica tiene normas para investigar y sancionar las Prácticas colusorias; los Abusos de posición de dominio; las normas  para el control de concentraciones económicas; las conductas de Abuso de dependencia económica, y las conductas  de competencia desleal.  Siempre la Autoridad de Competencia analizará estas conductas en función del bienestar del mercado y del consumidor.

Amperometric detection of carbohydrates based on the glassy carbon electrode modified with gold nano-flake layer

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Huy Du Nguyen

2015-09-01

Full Text Available An electro-deposition approach was established to incorporate the gold nano-flakes onto the glassy carbon electrode in electrochemical cells (nano-Au/GC/ECCs. Using pulsed amperometric detection (PAD without any gold oxidation for cleaning (non-oxidative PAD, the nano-Au/GC/ECCs were able to maintain their activity for oxidizing of carbohydrates in a normal alkaline medium. The reproducibility of peak area was about 2 relative standard deviation (RSD,% for 6 consecutive injections. A dynamic range of carbohydrates was obtained over a concentration range of 5–80 mg L−1 and the limits of detection (LOD were of 2 mg L−1 for fructose and lactose and 1 mg L−1 for glucose and galactose. Moreover, the nano-Au/GC/ECC using the non-oxidative PAD was able to combine with the internal standard method for determination of lactose in fresh cow milk sample.

Effect of functionalization of boron nitride flakes by main group metal clusters on their optoelectronic properties

Science.gov (United States)

Chakraborty, Debdutta; Chattaraj, Pratim Kumar

2017-10-01

The possibility of functionalizing boron nitride flakes (BNFs) with some selected main group metal clusters, viz. OLi4, NLi5, CLi6, BLI7 and Al12Be, has been analyzed with the aid of density functional theory (DFT) based computations. Thermochemical as well as energetic considerations suggest that all the metal clusters interact with the BNF moiety in a favorable fashion. As a result of functionalization, the static (first) hyperpolarizability (β ) values of the metal cluster supported BNF moieties increase quite significantly as compared to that in the case of pristine BNF. Time dependent DFT analysis reveals that the metal clusters can lower the transition energies associated with the dominant electronic transitions quite significantly thereby enabling the metal cluster supported BNF moieties to exhibit significant non-linear optical activity. Moreover, the studied systems demonstrate broad band absorption capability spanning the UV-visible as well as infra-red domains. Energy decomposition analysis reveals that the electrostatic interactions principally stabilize the metal cluster supported BNF moieties.

A QUÍMICA NA ODONTOLOGIA: CONTRIBUIÇÕES PARA O ENSINO

OpenAIRE

Greyce Arrúa Storgatto

2016-01-01

Esta pesquisa considera a temática Química na Odontologia como ponto de partida para a contextualização de conteúdos químicos, a fim de contribuir para o processo de ensino e aprendizagem de conteúdos de Química para estudantes de 3 série do Ensino Médio de uma escola estadual da cidade de Santa Maria, RS. Ao tratar da Química envolvida em materiais comuns na prática odontológica, bem como ao abordar problemas comuns de saúde bucal e aspectos de sua prevenção e tratamento, a Qu...

Una solución dinámica para juegos con utilidades transferibles

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Juan Carlos Cesco

2008-01-01

Full Text Available En este trabajo definimos un tipo de solución dinámica para juegos con utilidades transferibles. La solución dinámica fue introducida por Shenoy (1980 en el marco de juegos abstractos como un medio para describir algunos procesos de negociación. En el contexto de los juegos con utilidades transferibles estudiamos su comportamiento tanto en la clase de los juegos equilibrados (con Core no vacío como en el de los juegos no equilibrados. En esta última subclase mostramos que la solución dinámica debe contener los elementos de ciertos ciclos de preimputaciones denominados ciclos maximales. Estos ciclos aparecen en relación con un esquema dinámico elaborado originalmente para aproximar puntos en el Core de un juego. En la subclase de los juegos equilibrados, la solución dinámica coincide con el Core, lo que establece un enfoque unificado de solución. El problema de existencia de ciclos maximales no está completamente resuelto, pero en algunas subclases de juegos podemos exhibir teoremas de existencia y una descripción completa de la solución dinámica.

EL PAPEL DE LA QUÍMICA ANALÍTICA EN LAS CIENCIAS AMBIENTALES

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María A. Dosal

2014-01-01

Full Text Available En este trabajo se presenta una propuesta para abordar la didáctica de la Química Analítica con enfoque de Química Sostenible y de Control de Calidad. Esta propuesta considera un conocimiento razonado de la reactividad química y el diseño de experiencias prácticas representativas de equilibrios químicos en las que se utilicen técnicas comunes pa ra análisis cuantitativo; las experiencias que se proponen fueron diseñadas de acuerdo c on los Principios de la Química Verde buscando iniciar al futuro profesional en el diseño de procesos químicos escalables a nivel industrial y acordes con los requerimi entos de una civilización sostenible; todas fueron probadas y aceptadas por estudiantes de licenciatura y posgrado.

Layered graphene-mica substrates induce melting of DNA origami

Science.gov (United States)

Green, Nathaniel S.; Pham, Phi H. Q.; Crow, Daniel T.; Burke, Peter J.; Norton, Michael L.

2018-04-01

Monolayer graphene supported on mica substrates induce melting of cross-shaped DNA origami. This behavior can be contrasted with the case of origami on graphene on graphite, where an expansion or partially re-organized structure is observed. On mica, only well-formed structures are observed. Comparison of the morphological differences observed for these probes after adsorption on these substrates provides insights into the sensitivity of DNA based nanostructures to the properties of the graphene monolayer, as modified by its substrate.

Caracterização anatômica e química de folhas de Jacaranda puberula (Bignoniaceae presente na Mata Atlântica

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Maria Bernadete Gonçalves Martins

Full Text Available A espécie Jacaranda puberula (Bignoniaceae é conhecida popularmente como "carobinha" sendo utilizada na medicina popular em comunidades tradicionais. O objetivo deste trabalho foi realizar a caracterização anatômica e química das folhas de J. puberula. Para a análise anatômica utilizou-se a microscopia de luz e microscopia eletrônica de varredura (MEV. Para a análise química utilizou-se a Cromatografia Líquida de Alta Eficiência (CLAE. O mesofilo é dorsiventral, a epiderme unisseriada com cutícula espessa, tricomas glandulares do tipo peltado e tricomas tectores em ambas as faces da epiderme, parênquima clorofiliano com duas a três camadas de células paliçádicas e quatro a cinco camadas de células formando o parênquima lacunoso, de tamanho pequeno, com muitos espaços intercelulares, hipoestomática com nervura pinada. Os estudos através de MEV evidenciaram a epiderme recoberta com cera epicuticular e glândulas peltadas com maior incidência na epiderme da face abaxial, constituídas por oitos células secretoras apicais. A análise cromatográfica do extrato etanólico evidenciou a presença de fitoquinóides e flavonóides.

Ecología química en el bentos antártico

OpenAIRE

Ballesteros, Manuel (Ballesteros Vázquez); Núñez Pons, Laura; Vázquez, J.; Cristobo, F.J.; Taboada Moreno, Sergio; Figuerola Balañá, Blanca; Ávila Escartín, Conxita

2011-01-01

El estudio de las interacciones entre los organismos mediadas por sustancias químicas, lo que se denomina ecología química, nos da información sobre la biología de las especies implicadas, el funcionamiento de la comunidad en que viven y nos puede proporcionar además el conocimiento de nuevas sustancias que pueden ser útiles para el ser humano. En el marco de nuestros estudios sobre la ecología química de los invertebrados antárticos, en el proyecto ECOQUIM (2003-2006) se recolectaron numeros...

Caracterización química de la cerámica arqueológica de Cotahuasi mediante análisis por activación neutrónica

OpenAIRE

Bedregal, Patricia; Mendoza, Pablo; Ubillús, Marco; Montoya, Eduardo

2010-01-01

Se ha determinado las concentraciones de As, Ba, Ce, Co, Cr, Cs, Eu, Fe, Hf, La, Na, Rb, Sb, Sc, Sm, Th, Yb, en 121 fragmentos de cerámicos arqueológicos encontrados en el valle de Cotahuasi, mediante análisis por activación neutrónica instrumental, según el método k-subcero. Se ha comparado los resultados con la composición química elemental de la cerámica Tiwanaku y la cerámica Wari de Ayacucho y Cusco, encontrándose que los grupos de Ayacucho, Cotahuasi, Cusco y Tiwanaku se encuentran sepa...

Emission properties of Ga2O3 nano-flakes: effect of excitation density.

Science.gov (United States)

Pozina, G; Forsberg, M; Kaliteevski, M A; Hemmingsson, C

2017-02-08

In the quest of developing high performance electronic and optical devices and more cost effective fabrication processes of monoclinic β-Ga 2 O 3 , new growth techniques and fundamental electronic and optical properties of defects have to be explored. By heating of dissolved metallic Ga in HCl in a NH 3 and N 2 atmosphere, nano-flake films of monoclinic β-phase Ga 2 O 3 were grown as confirmed by XRD. From optical measurements, we observe two strong emissions. A red band peaking at ~2.0 eV and a UV band at ~3.8 eV. The band at ~2.0 eV is attributed to donor-acceptor pair recombination where the donor and acceptor level is suggested to be related to V O and nitrogen, respectively. By studying the dependence of the intensity of the UV band at 3.8 eV versus excitation density, a model is suggested. In the model, it is assumed that local potential fluctuations forming minima (maxima), where the carriers would be localized with a summarized band offset for conduction and valence band of 1 eV. The origin of the fluctuations is tentatively suggested to be related to micro-inclusions of different phases in the film.

Farmacogenómica: Aplicaciones cardiovasculares

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Luis Quiñones S., PH.D.

2015-03-01

Este trabajo pretende dar una visión general acerca de farmacogenómica cardiovascular y la posibilidad de utilizar, en la consulta clínica, herramientas genéticas para apoyar la decisión farmacoterapéutica, con el objeto de mejorar la respuesta al tratamiento de enfermedades cardiovasculares, un paso hacia la medicina personalizada en Chile.

Interacciones sociales y explotación económica

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Andrés Montaña

2012-01-01

se desarrollan interacciones sociales. El modelo permite identificar la posición de un agente en el espacio social y hacer comparaciones interpersonales. A partir del modelo de interacción social general, planteo un modelo de explotación económica. Una autoridad desde este modelo de explotación puede establecer áreas de restricción para determinar la explotación económica de los agentes. El cálculo de las dotaciones y las combinaciones de éstas, pueden permitir a una autoridad determinar si existe o no explotación de unos agentes por otros, fijar categorías de explotación, e identificar áreas de atención prioritarias. El modelo se podría constituir en una herramienta más apropiada para la identificación de la condición laboral o económica de los niños y niñas.

Antropología Económica: una Reseña Introductoria

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Norberto G. Demonte

2007-12-01

Full Text Available El artículo expone las principales perspectivas teóricas de la antropología económica, entendida como el estudio de los procesos de producción, distribución, circulación y consumo enlas sociedades precapitalistas. Se presenta a la antropología económica comoun área de complementación de esfuerzos entre economistas, historiadores y antropólogos, resaltando su importancia en las facultades de ciencias económicas. Se comentan brevemente las cuestiones fundamentales de esta ciencia,tales como la discusión sobre el carácter abstracto de la economía, la polémica entre sustantivistas y formalistas, los aportes dediversos estudios etnográficos, la perspectiva de la escuela marxista y la controversia entre materialistas y culturalistas. Finalmente, el trabajo detalla las líneas de investigación en América Latina y en Argentina y brinda una abundante bibliografía para profundizar los aspectos de interés para el investigador.

Diagenetic replacement of Micas by Carbonates

NARCIS (Netherlands)

Oele, E.

1961-01-01

In the Ordovician sandstones of the Cantabrian Mountains a replacement of the micas by carbonate minerals could be observed. The absence of metamorphic minerals suggests a diagenetic replacement. This is supported by the finding of the same type of replacement in some undisturbed Pliocene sediments

CARACTERIZAÇÃO ANATÔMICA E HISTOQUÍMICA DAS FOLHAS DE EUGENIA UNIFLORA L.

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Rafaela Damasceno Sá

2016-10-01

Full Text Available Eugenia uniflora L., popularmente conhecida como pitangueira, é uma importante frutífera muito utilizada na medicina tradicional brasileira para o tratamento de diarreia e disenteria, gripe, parasitas intestinais, febre, hipertensão e como calmante e diurético. Devido ao seu amplo interesse popular e com o intuito de ampliar as informações farmacobotânicas da espécie, este trabalho tem como objetivo realizar a caracterização anatômica e histoquímica das folhas de E. uniflora. Foram confeccionadas e analisadas em microscópico de luz lâminas semipermanentes contendo secções transversais de pecíolo e lâmina foliar, além de secções paradérmicas de lâmina foliar. Realizou-se também testes histoquímicos em secções transversais de lâmina foliar A análise microscópica permitiu a identificação de estruturas importantes na diagnose da espécie: cavidades secretoras no pecíolo e na lâmina foliar; cristais prismáticos no floema do pecíolo e da lâmina foliar, bem como no mesofilo e nas células parenquimáticas e colenquimáticas da nervura central; drusas estão presentes apenas no parênquima do pecíolo e no mesofilo, parênquima e colênquima da lâmina foliar; presença de cutícula espessa no pecíolo e na lâmina foliar; feixes vasculares bicolaterais e mesofilo dorsiventral, com parênquima paliçádico bisseriado. Através da histoquímica evidenciou-se na lâmina foliar a presença de compostos fenólicos, taninos, lignina, compostos lipofílicos, óleos essenciais, triterpenos e esteroides e cristais de oxalato de cálcio. Os resultados apresentados são úteis para a identificação correta da espécie.

A COMPLEXIDADE ECONÔMICA DOS DIREITOS HUMANOS: UMA DIMENSÃO ESCONDIDA DO DESENVOLVIMENTO HUMANO

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Leilane Serratine Grubba

2012-10-01

Full Text Available Este artigo tem por objeto a complexidade econômica dos direitos humanos, mais precisamente, a investigação da relação entre a complexidade econômica e o desenvolvimento humano. Nesse sentido, objetivou demonstrar a intrínseca relação e dependência do desenvolvimento humano à complexidade econômica dos direitos humanos, que influi na positivação dos direitos, assim como na luta pelo acesso aos bens necessários a uma vida digna. Por meio do método dedutivo, o artigo problematizou a relação entre o ser humano e seu contexto econômico-social para o desenvolvimento da vida em dignidade. Diante disso, em primeiro lugar, foi apresentada a noção de complexidade dos direitos humanos, isto é, as suas múltiplas dimensões. No segundo momento, foi analisada a questão econômica do desenvolvimento humano, ou seja, a relação entre o desenvolvimento da vida digna e a dimensão econômica da sociedade, e, finalmente, foi apresentada a complexidade econômica dos direitos humanos. O desenvolvimento humano não está apenas vinculado à dimensão econômica, mas compreende todas as dimensões (complexidade que perfazem uma vida digna de ser vivida. A vida se desenvolve em dignidade mediante o acesso aos bens materiais e imateriais. As políticas do desenvolvimento humano, nesse sentido, devem se integrar a uma estrutura que apoie um crescimento com equidade e sustentabilidade. Palavras-chave: Pensamento complexo. Complexidade econômica. Direitos humanos. Desenvolvimento humano. Dignidade humana.

Síntesis y Caracterización de Microesferas Cerámicas

NARCIS (Netherlands)

Quercia Bianchi, G.

2007-01-01

El presente estudio se basó en la utilización de materiales de desecho tipo escoria, para la producción de microesferas cerámicas de bajo costo, con el objetivo principal de profundizar en las metodologías de producción de estas a escala nacional. Generalmente las microesferas cerámicas son

VARIABLES MACROECONÓMICAS Y MICROECONÓMICAS QUE INFLUYEN EN LA ESTIMACIÓN DEL COSTO DE CAPITAL: UN ESTUDIO DE CASO

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DANIEL CARDONA ECHEVERRI

2017-01-01

Full Text Available Este artículo identifica y contrasta la significancia estadística de variables macroeconómicas y mi- croeconómicas, que desde la teoría pueden influir sobre el costo de capital. Utilizando información de las empresas listadas en la Bolsa de Valores de Colombia (BVC entre los periodos 2003-4 a 2012-1 y modelos de paneles dinámicos para explicar el Costo de Capital Promedio Ponderado (WACC, se encuentra que la mayoría de las variables propuestas resultan estadísticamente significativas, así mismo se prueba la e xistencia de inercia entre el costo de capital actual y el del periodo pasado.

Cerámicas Estampilladas de Salvatierra de Tormes (Salamanca. Contribución al Estudio de las Cerámicas Tardorromanas del Valle del Duero

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Enrique CERRILLO MARTÍN DE CÁCERES

2009-10-01

Full Text Available Dentro del conjunto de yacimientos del Valle del Duero han sido exhaustivamente analizados diversos materiales en bloque (cuchillos, bronces, vidrios, adornos de uso personal, etc. que ponen de manifiesto una indudable unidad cultural de esta zona en un momento determinado, concretamente en los siglos iv y v d. de C. Sin embargo, y a pesar de que el Prof. Palol promete un estudio sobre las cerámicas tardorromanas de estos yacimientos, añadimos a las ya conocidas un lote bastante homogéneo de cerámicas de factura local, pero que a pesar de ello observan unos caracteres muy concretos e interesantes para el estudio de la cerámica del Duero en estos momentos que siempre han quedado vacíos al clasificar cronológicamente los hallazgos, bien de época romana, o bien de época visigoda.

Measurement of friction force between two mica surfaces with multiple beam interferometry

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Jung J.C.

2010-06-01

Full Text Available Friction forces play a crucial role in the tribological behaviour of microcomponents and the application of MEMS products. It is necessary to develop a measurement system to understand and control the material characteristics. In this study, a microscopic measurement system based on multiple beam interferometry is developed to measure the friction force between two mica thin films. Some frictional behaviour between the two mica sheets in contact are reported. The evaluated shear strength of mica agrees well to the existing data. It is possible to use the developed system for micro-tribology study.

La influencia socioeconómica en el comportamiento de juego de preescolares

OpenAIRE

Pfeifer, Luzia Iara; Rombe, Patrícia Gonçalves; Santos, Jair Licio Ferreira

2009-01-01

Considerando que o contexto econômico influencia o brincar de crianças, este trabalho teve por objetivo analisar as diferenças entre os brinquedos utilizados por crianças de duas diferentes classes socioeconômicas. Os dados foram coletados junto a 50 mães de crianças com idade entre três e seis anos, metade pertencentes à classe econômica A2 (Grupo 2), e a outra metade pertencente à classe econômica D (Grupo 1), segundo o Critério Brasil. Os resultados apontam para a existência de diferenças ...

El origen de la cerámica en el Este de Asia

OpenAIRE

Sola Fernández de Zuazo, Garazi

2017-01-01

Este trabajo trata sobre el origen de la cerámica. Las teorías tradicionales situaban esta innovación en el Próximo Oriente durante la “Revolución Neolítica” descrita por Gordon Childe. En cambio, los nuevos descubrimientos realizados en yacimientos del Este de Asia nos muestran que la cerámica apareció varios milenios antes en esta zona. La cerámica más antigua fue hallada en yacimientos en cuevas del sur de China y presenta una cronología varios milenios anterior a la aparición de asentamie...

Molecular regulation of MICA expression after HDAC inhibitor treatment of cancer cells

DEFF Research Database (Denmark)

Jensen, Helle

and NKG2D-ligands are upregulated on the surface of abnormal cells. We have previously shown that cancer cells can be stimulated to express the NKG2D-ligands MICA/B after exposure to HDAC-inhibitors (HDAC-i), an occurrence that is not observed in healthy cells. Here we characterize the molecular signal...... pathways that lead to MICA expression after HDAC-inhibitor treatment of cancer cells. Chelating Calcium with Bapta-AM or EGTA potently inhibited HDAC-inhibitor and CMV mediated MICA/B expression. It was further observed that ER Calcium stores were depleted after HDAC-inhibitor treatment. NF-kB activity can...

Enseñanza de química a alumnos con discapacidad visual

OpenAIRE

Gerson de Souza, M.; Patrícia Neves, R.; Rejane Ferreira, P.

2009-01-01

La educación formal en Brasil tiene como primer principio la “igualdad de condiciones de acceso y permanencia en la escuela” (Brasil, 1996). En este contexto, el proyecto “Enseñanza de Química a Alumnos con Discapacidad Visual” busca desarrollar recursos y metodologías para una enseñanza de Química que atienda alumnos con ceguera o baja visión. En este proyecto, con el objetivo de atender alumnos y profesores de la enseñanza secundaria, iniciamos la adaptación del libro “Química e Sociedade” ...

Aprendizaje autorregulado, metas académicas y rendimiento en evaluaciones de estudiantes universitarios

Directory of Open Access Journals (Sweden)

Marcela Valencia Serrano

2013-01-01

Full Text Available Objetivo. Explorar la relación entre aprendizaje autorregulado, metas académicas y rendimiento en una evaluación académica de ocho estudiantes universitarias. Método. Se realizó una entrevista semi- estructurada, una observación directa de una sesión de estudio y protocolos verbales durante y después de la sesión. Resultados. En relación con las metas académicas, se encontró que tres estudiantes tuvieron u na única orientación a metas de dominio por aproximación, mientras que cinco orien taron a múltiples metas académicas. Respecto al aprendizaje autorregulado, se encontraron estudiantes con b ajos y altos niveles. En la relación entre aprendizaje autorregulado, metas académicas y rendimiento en la evaluación fue posible identificar tres grupos de estudiantes: (a altos niveles de autorregulación y orientación única a metas de dominio por aproximación, (b bajos niveles de autorregulación y múltipl e orientación a metas de dominio y ejecución en tendencias de aproximación y evitación, y (c variaciones en el nivel de autorregulación con múltiple orientación a metas académicas. Todas las estudiantes obtuvieron cali ficaciones aprobatorias en la evaluación, independientemente de su nivel de autorregulación y de la orientaci ón a metas académicas. Conclusión. El abordaje procedimental del aprendizaje autorregulado, en función de las metas académicas, permitió obtener información relevante para la comprensión de este proceso, por lo que se recomienda seguir realizando este tipo de estudios para dar cuenta de los diferentes fu ncionamientos de las estudiantes universitarias en tiempo real, de sus variaciones y relación con otros aspectos motivacionales involucrados en sus procesos de aprendizaje.

Caracterización de la región cromosómica 15q11-q13 del genoma humano. Variabilidad genómica en el autismo e identificación de ncRNAs

OpenAIRE

Cerrato Rivera, Celia

2007-01-01

La tesis doctoral con título "Caracterización de la región cromosómica 15q11-13 del genoma humano. Variabilidad genómica en el autismo e identificación de ncRNAs" se basa en el estudio de la región cromosómica 15q11-q13, centrándonos en los aspectos de la variabilidad genómica y su significado funcional. En la primera parte del estudio buscamos reordenamientos de 15q11-q13 en pacientes con autismo, mediante la genotipación de marcadores microsatélites cubriendo dicha región, y definimos una d...

Growth of nano hexagon-like flake arrays cerium carbonate created with PAH as the substrate

Energy Technology Data Exchange (ETDEWEB)

Li, M., E-mail: limei@imust.cn [School of Materials Science and Engineering, Beijing University of Chemical Engineering, Department of Materials, Beijing 100029 (China); School of Materials and Metallurgy, Inner Mongolia University of Science and Technology, Department of Inorganic and Metalloid Materials, Key Laboratory of New Technologies of Modern Metallurgy and Application of Rare Materials, Baotou 014010 (China); Hu, Y.H., E-mail: bthyh@163.com [School of Materials Science and Engineering, Beijing University of Chemical Engineering, Department of Materials, Beijing 100029 (China); School of Materials and Metallurgy, Inner Mongolia University of Science and Technology, Department of Inorganic and Metalloid Materials, Key Laboratory of New Technologies of Modern Metallurgy and Application of Rare Materials, Baotou 014010 (China); Liu, Z.G.; Wang, X.F.; Wang, M.T. [School of Materials and Metallurgy, Inner Mongolia University of Science and Technology, Department of Inorganic and Metalloid Materials, Key Laboratory of New Technologies of Modern Metallurgy and Application of Rare Materials, Baotou 014010 (China)

2015-01-15

Petals-like Ce{sub 2}(CO{sub 3}){sub 3} on Ce{sub 2}(CO{sub 3}){sub 3} nano hexagon-like flake arrays have been precipitatingly fabricated using PAH substrates. By changing the way of feeding, PAH concentration and aging time, petals-like Ce{sub 2}(CO{sub 3}){sub 3} was created best when adding PAH into the Ce(NO{sub 3}){sub 3} solution, joined (NH{sub 4}){sub 2}CO{sub 3} solution along with mixing, PAH concentration is 0.9 g/L, aging time is 4 h. A growth mechanism was proposed to account for the growth of the petals-like Ce{sub 2}(CO{sub 3}){sub 3} with PAH as the substrate. Poly allylamine hydrochloride (PAH) is as template agent which forms π-allyl complex with Ce{sup 3+} and controls the morphology of Ce{sub 2}(CO{sub 3}){sub 3} particle. PAH and Ce{sup 3+} form π-allyl complex, and then induce the formation of Ce{sub 2}(CO{sub 3}){sub 3} crystal nucleus. And infrared spectrum analysis verified. XRD show that after adding PAH which is adsorbed on the crystal plane, the growth of Ce{sub 2}(CO{sub 3}){sub 3} crystal is inhibited on (2 4 2), the growth is promoted on (2 0 2) which is differentiated into the new (1 5 1), (2 2 2) is unchanged, Ce{sub 2}(CO{sub 3}){sub 3} crystal is accumulated petals shape by hexagon-like flake. UV absorption spectra show that CeO{sub 2} as prepared precursor Ce{sub 2}(CO{sub 3}){sub 3} after calcinations in air at high temperatures, the petal-like CeO{sub 2} has strong UV absorption and reflection effects, and absorption interval changed significantly by the move to UVA from UVB. - Graphical abstract: Each Ce-atom connects three Cl-atoms and three allyls in three dimensional spaces. To take the plane as a reference plane which is arrayed with three Ce-atom as equilateral triangle. The triangular each vertex is Ce-atom, the triangular center place is Cl-atom, the equilateral triangle which is mutually perpendicular with Ce-triangle surface and the inclined angle is 60° is made up with three Cl-atoms. - Highlights: • Petals

La industria cerámica brasileña

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Pacheco Jordao, M. A.

2001-02-01

Full Text Available Ceramics play an important role in the Brazilian economy, with a participation estimated in 1% of the GNP ( Gross National Product, corresponding to about 6 billion dollars. The abundance of natural raw-materials, alternative energy sources, and the availability of practical technologies within the industrial equipments, caused a rapid evolution of the Brazilian industries, and several types of products from the various ceramic segments attained international quality levels, with significative exportation. He ceramic sector is very diverse and can be divided into the following classes: heavy clay ceramics, wall and floor tiles, refractory materials, sanitary ware, porcelain electric insulators, tableware, decorative china, ceramic filters and reservoirs for domestic use, technical ceramics, and thermal insulators. All these segments exist in Brazil, in a higher or lower stage of development and production capacity. Moreover, there are also manufacturers of synthetic glazes and colorants, plaster of paris, equipments and some auxiliary chemicals. In this paper, an overview of the main Brazilian ceramic segments is presented, excluding the glass, cement, and lime sectors, which, despite being ceramic, are generally treated in separate.

La cerámica juega un papel muy importante para la economía del país brasileño con una participación en el P.I.B (Producto Interior Bruto estimado en el 1%, correspondiendo a cerca de 6 millones de dólares. La abundancia de materias primas naturales, fuentes alternativas de energía y una amplia tecnología incorporada a los equipos industriales, han hecho que las industrias brasileñas evolucionasen rápidamente de forma que muchos tipos de productos de diferentes segmentos de la actividad cerámica alcanzasen niveles de calidad mundial, con cifras apreciables destinadas a la exportación. El sector industrial de la cerámica incluye producciones muy diversificados y puede ser dividido en los siguientes

Broad MICA/B Expression in the Small Bowel Mucosa: A Link between Cellular Stress and Celiac Disease

Science.gov (United States)

Allegretti, Yessica L.; Bondar, Constanza; Guzman, Luciana; Cueto Rua, Eduardo; Chopita, Nestor; Fuertes, Mercedes; Zwirner, Norberto W.; Chirdo, Fernando G.

2013-01-01

The MICA/B genes (MHC class I chain related genes A and B) encode for non conventional class I HLA molecules which have no role in antigen presentation. MICA/B are up-regulated by different stress conditions such as heat-shock, oxidative stress, neoplasic transformation and viral infection. Particularly, MICA/B are expressed in enterocytes where they can mediate enterocyte apoptosis when recognised by the activating NKG2D receptor present on intraepithelial lymphocytes. This mechanism was suggested to play a major pathogenic role in active celiac disease (CD). Due to the importance of MICA/B in CD pathogenesis we studied their expression in duodenal tissue from CD patients. By immunofluorescence confocal microscopy and flow cytometry we established that MICA/B was mainly intracellularly located in enterocytes. In addition, we identified MICA/B+ T cells in both the intraepithelial and lamina propria compartments. We also found MICA/B+ B cells, plasma cells and some macrophages in the lamina propria. The pattern of MICA/B staining in mucosal tissue in severe enteropathy was similar to that found in in vitro models of cellular stress. In such models, MICA/B were located in stress granules that are associated to the oxidative and ER stress response observed in active CD enteropathy. Our results suggest that expression of MICA/B in the intestinal mucosa of CD patients is linked to disregulation of mucosa homeostasis in which the stress response plays an active role. PMID:24058482

Caracterização fitoquímica e físico-química das folhas de Bauhinia forficata Link coletada em duas regiões brasileiras

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Graziella Silvestre Marques

2012-01-01

Full Text Available Folhas da espécie vegetal Bauhinia forficata Link, popularmente conhecida como pata de vaca, apresentam amplo potencial terapêutico no tratamento do diabetes mellitus. Amostras desta espécie vegetal, obtidas em duas regiões do Brasil (Minas Gerais e Paraná, foram submetidas à caracterização fitoquímica e físico-química (granulometria, perda por dessecação, teor de cinzas e teor de extrativos para realização de um estudo comparativo entre indivíduos cultivados em regiões distintas, bem como estabelecimento de especificações para seu controle de qualidade. Para a caracterização fitoquímica, extratos metanólicos das amostras foram avaliados através de cromatografia de camada delgada (CCD para pesquisa das principais classes de metabolitos secundários. Enquanto que, para as análises físico-químicas foram adotadas metodologias farmacopeicas. A análise estatística dos dados realizouse através dos testes F de Fischer e t de Student. De acordo com a avaliação fitoquímica foi possível observar um perfil similar para ambas as amostras com presença dos seguintes grupos: flavonóides, proantocianidinas, leucoantocianidinas, triterpenos, esteróides, açúcares redutores, além de substâncias antioxidantes com bandas coincidentes às dos compostos flavonoídicos. Por outro lado, as amostras apresentaram algumas propriedades físico-químicas diferentes tais como granulometria e umidade residual em virtude da origem e do processamento adotados pelos fornecedores. Já os valores do teor de cinzas mostraram-se dentro das especificações e não foi observada diferença significativa para o teor de extrativos. Os resultados obtidos neste trabalho contribuíram no processo de identificação e padronização de parâmetros de qualidade para as folhas de B. forficata.

Influence of the surface free energy of silane-coupled mica substrate on the fixing and straightening of DNA

International Nuclear Information System (INIS)

Sasou, Megumi; Sugiyama, Shigeru; Ishida, Takao; Ohtani, Toshio; Miyake, Koji

2009-01-01

Methyltrimethoxysilane (MTMS)-coupled mica substrate is reportedly suitable for fixing and straightening of DNA, but 3-aminopropyltriethoxysilane (APTES)-coupled mica substrate has been found less suitable. On MTMS-coupled mica substrate, the straightness of fixed DNA was sufficient, and the adsorption of contaminants was not observed using fluorescence microscopy and atomic force microscopy. For the APTES-coupled mica substrate, however, aggregated or curved DNA and adsorption of contaminants were observed. To clarify the surface factors that are responsible for this suitability, we analyzed the surface free energies of these substrates using the extended Fowkes theory. In each of the surface free energy components, the dispersion force component in the MTMS-coupled mica substrate was lower than that in the APTES-coupled mica substrate. The ratio of the polar force component on the MTMS-coupled mica substrate was about one order of magnitude on the APTES-coupled mica substrate. In addition, the ratio of the hydrogen-bonding force component for the MTMS-coupled mica substrate was about two times larger than that of the APTES-coupled mica substrate. These results suggest that the polar force and hydrogen-bonding force components are important factors for the fixation and straightening of DNA and that the dispersion force components influence the production and adsorption of contaminants.

La Alianza del Pacífico y Mercosur: evidencias de convergencia económica

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José Ustorgio Mora Mora

2016-10-01

Full Text Available Mediante el cálculo de un índice de convergencia económica y el análisis de correlaciones entre varias variables macroeconómicas, se estudia la posibilidad de convergencia económica entre los países miembros de la Alianza del Pacífico con los de Mercosur. Para ello se utiliza información estadística del periodo 1980-2014. A partir de lo anterior, los resultados no son concluyentes, no es posible determinar el rumbo a seguir por estos dos acuerdos para una expansión y una mayor integración económica, aunque los patrones observados sobre las decisiones de los países miembros para este objetivo sugieren que esta pudiera ser bastante factible en el mediano plazo y el índice de convergencia económica refleja esa tendencia. Sin embargo, el análisis de correlaciones no permite establecer una conclusión definitiva.

Não-linearidades: da dinâmica do simples à dinâmica do complexo

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José Roberto Castilho Piqueira

1994-01-01

Full Text Available Foram apresentados alguns conceitos relativos à utilização da Teoria dos Sistemas Dinâmicos em problemas de sistemas complexos. A apresentação destes conceitos centra-se no estabelecimento de duas dinâmicas: uma de curto termo e outra de longo termo, relacionando-as com os processos de organização dos sistemas.

Association of MICA gene polymorphisms with liver fibrosis in schistosomiasis patients in the Dongting Lake region

Energy Technology Data Exchange (ETDEWEB)

Gong, Zheng; Luo, Qi-Zhi; Lin, Lin [Department of Immunology, College of Basic Medical Sciences, Central South University, Changsha, Hunan Province (China); Su, Yu-Ping; Peng, Hai-Bo [Central Blood Bank in Yueyang, Yueyang, Hunan Province (China); Du, Kun; Yu, Ping [Department of Immunology, College of Basic Medical Sciences, Central South University, Changsha, Hunan Province (China); Wang, Shi-Ping [Key Laboratory of Schistosomiasis in Hunan, Department of Parasitology, College of Basic Medical Sciences, Central South University, Changsha, Hunan Province (China)

2012-03-02

Major histocompatibility complex class I chain-related A (MICA) is a highly polymorphic gene located within the MHC class I region of the human genome. Expressed as a cell surface glycoprotein, MICA modulates immune surveillance by binding to its cognate receptor on natural killer cells, NKG2D, and its genetic polymorphisms have been recently associated with susceptibility to some infectious diseases. We determined whether MICA polymorphisms were associated with the high rate of Schistosoma parasitic worm infection or severity of disease outcome in the Dongting Lake region of Hunan Province, China. Polymerase chain reaction-sequence specific priming (PCR-SSP) and sequencing-based typing (SBT) were applied for high-resolution allele typing of schistosomiasis cases (N = 103, age range = 36.2-80.5 years, 64 males and 39 females) and healthy controls (N = 141, age range = 28.6-73.3 years, 73 males and 68 females). Fourteen MICA alleles and five short-tandem repeat (STR) alleles were identified among the two populations. Three (MICA*012:01/02, MICA*017 and MICA*027) showed a higher frequency in healthy controls than in schistosomiasis patients, but the difference was not significantly correlated with susceptibility to S. japonicum infection (Pc > 0.05). In contrast, higher MICA*A5 allele frequency was significantly correlated with advanced liver fibrosis (Pc < 0.05). Furthermore, the distribution profile of MICA alleles in this Hunan Han population was significantly different from those published for Korean, Thai, American-Caucasian, and Afro-American populations (P < 0.01), but similar to other Han populations within China (P > 0.05). This study provides the initial evidence that MICA genetic polymorphisms may underlie the severity of liver fibrosis occurring in schistosomiasis patients from the Dongting Lake region.

Association of MICA gene polymorphisms with liver fibrosis in schistosomiasis patients in the Dongting Lake region

International Nuclear Information System (INIS)

Gong, Zheng; Luo, Qi-Zhi; Lin, Lin; Su, Yu-Ping; Peng, Hai-Bo; Du, Kun; Yu, Ping; Wang, Shi-Ping

2012-01-01

Major histocompatibility complex class I chain-related A (MICA) is a highly polymorphic gene located within the MHC class I region of the human genome. Expressed as a cell surface glycoprotein, MICA modulates immune surveillance by binding to its cognate receptor on natural killer cells, NKG2D, and its genetic polymorphisms have been recently associated with susceptibility to some infectious diseases. We determined whether MICA polymorphisms were associated with the high rate of Schistosoma parasitic worm infection or severity of disease outcome in the Dongting Lake region of Hunan Province, China. Polymerase chain reaction-sequence specific priming (PCR-SSP) and sequencing-based typing (SBT) were applied for high-resolution allele typing of schistosomiasis cases (N = 103, age range = 36.2-80.5 years, 64 males and 39 females) and healthy controls (N = 141, age range = 28.6-73.3 years, 73 males and 68 females). Fourteen MICA alleles and five short-tandem repeat (STR) alleles were identified among the two populations. Three (MICA*012:01/02, MICA*017 and MICA*027) showed a higher frequency in healthy controls than in schistosomiasis patients, but the difference was not significantly correlated with susceptibility to S. japonicum infection (Pc > 0.05). In contrast, higher MICA*A5 allele frequency was significantly correlated with advanced liver fibrosis (Pc < 0.05). Furthermore, the distribution profile of MICA alleles in this Hunan Han population was significantly different from those published for Korean, Thai, American-Caucasian, and Afro-American populations (P < 0.01), but similar to other Han populations within China (P > 0.05). This study provides the initial evidence that MICA genetic polymorphisms may underlie the severity of liver fibrosis occurring in schistosomiasis patients from the Dongting Lake region

Effect of synthetic mica on the thermal properties of poly(lactic acid

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Diego Holanda Saboya Souza

2014-01-01

Full Text Available Poly(lactic acid/Somasif fluoromica nanocomposites were prepared by melt blending and their thermal properties investigated by DSC, TGA and DMA. Three different types of synthetic mica (Somasif ME-100, Somasif MAE and Somasif MPE were used at different contents (2.5, 5.0 and 7.5 wt %. The melt blending of PLA and these micas is characterized by a considerable reduction in the matrix molecular weight, which decreases when the nanofiller content is increased. For all nanocomposites, the thermal stability increases when mica is added to the polymer, with the Somasif MPE, producing the highest increase of the degradation temperature and highest reduction of Tg.

Otra ciencia económica

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Daniel Innerarity

2012-04-01

Full Text Available El autor hace una crítica a la pretensión de la ciencia económica de constituirse como un saber exacto e hiperespecializado al considerar que esta pretensión se ha traducido en una pérdida de la capacidad que es necesaria para comprender la complejidad social de las realidades económicas. Seducida por el objetivo de la exactitud, la economía parece haber olvidado su carácter de construcción social. Además, la economía ha olvidado que es una más entre las ciencias sociales y el largo periodo en el que se ha separado de ellas reivindicando su plena autonomía no ha sido satisfactorio ni para ella ni para el resto de las ciencias sociales. Según el autor la crítica al capitalismo contemporáneo, si quiere ser más radical que moralizante, debe dirigirse a combatir el supuesto realismo de la ciencia económica dominante.The author criticizes the pretension of economic sciences of being an exact science and its tendency to specialization. The consequences of those pretensions are a loss of its capacity to understand the social complexity of the economic realities. The economy, seduced by its aim of exactitude, seems to forget that it is a social construction. Moreover, economy seems to forget that it is just a social science, and for a long period of time economy evolved as a separated and autonomous science; that time was not good neither for economic science neither for social sciences in general. According to the author, if we want to build a more radical and not only moralizing critique to contemporary capitalism, we must criticize the hypothetical realism of the economic science. 

Towards completely miscible PMMA nanocomposites reinforced by shear-stiff, nano-mica.

Science.gov (United States)

Ziadeh, Mazen; Weiss, Stephan; Fischer, Bianca; Förster, Stephan; Altstädt, Volker; Müller, Axel H E; Breu, Josef

2014-07-01

Optimizing the reinforcement of polymers with nanoplatelets requires optimization of the aspect ratio and the moduli of the filler while providing a complete stress transfer. Employing a novel shear-stiff, nano-mica with large aspect ratio, we focus on maximizing the interfacial interaction between filler and matrix. External surfaces of the nano-mica were selectively modified by a polycationic macro-initiator and two PMMA-polymer brushes of length below and above critical entanglement length, respectively, and the mechanical properties of the three PMMA nanocomposites were measured. The multiple electrostatic anchoring groups of the macro-initiator not only provide reliable adhesion but at the same time allow the variation of the degree of protonation providing a local match between the charge densities of the clay surface and the adsorbed macro-initiator. PMMA coating of the nano-mica via surface initiated polymerization yielded long-term stable suspensions in THF that showed birefringence of a nematic phase. Solution blending of the PMMA coated nano-mica allows for dispersing single clay tactoids in the translucent PMMA nanocomposites at 5 wt% clay loading as determined by transmission electron microscopy (TEM). Although significantly improved mechanical properties could be achieved as compared to nanocomposites made with conventional clay fillers, the full potential - as expressed by Halpin-Tsai equations - of the PMMA coated nano-mica can still not be completely utilized. This is attributed to the non-wetting character of the densely packed PMMA brushes attached to planar nanoplatelets. Copyright © 2014 Elsevier Inc. All rights reserved.

Fresh steam-flaked corn in cattle feedlots is an important site for fecal coliform contamination by house flies.

Science.gov (United States)

Ghosh, Anuradha; Zurek, Ludek

2015-03-01

House flies are a common pest at food animal facilities, including cattle feedlots. Previously, house flies were shown to play an important role in the ecology of Escherichia coli O157:H7; house flies in cattle feedlots carried this zoonotic pathogen and were able to contaminate cattle through direct contact and/or by contamination of drinking water and feed. Because house flies aggregate in large numbers on fresh ( # 6 h) steam-flaked corn (FSFC) used in cattle feed, the aim of this study was to assess FSFC in a cattle feedlot as a potentially important site of fecal coliform contamination by house flies. House flies and FSFC samples were collected, homogenized, and processed for culturing of fecal coliforms on membrane fecal coliform agar. Selected isolates were identified by 16S rRNA gene sequencing, and representative isolates from each phylogenetic group were genotyped by pulsed-field gel electrophoresis. Fecal coliforms were undetectable in FSFC shortly (0 h) after flaking; however, in summer, after 4 to 6 h, the concentrations of fecal coliforms ranged from 1.9 × 10(3) to 3.7 × 10(4) CFU/g FSFC (mean, 1.1 ± 3.0 × 10(4) CFU/g). House flies from FSFC carried between 7.6 × 10(2) and 4.1 × 10(6) CFU of fecal coliforms per fly (mean, 6.0 ± 2.3 × 10(5) CFU per fly). Fecal coliforms were represented by E. coli (85.1%), Klebsiella spp. (10.6%), and Citrobacter spp. (4.3%). Pulsed-field gel electrophoresis demonstrated clonal matches of E. coli and Klebsiella spp. between house flies and FSFC. In contrast, in winter and in the absence of house flies, the contamination of corn by fecal coliforms was significantly (∼10-fold) lower. These results indicate that FSFC is an important site for bacterial contamination by flies and possible exchange of E. coli and other bacteria among house flies. Further research is needed to evaluate the potential use of screens or blowers to limit the access of house flies to FSFC and therefore their effectiveness in preventing

Nutrigenómica, obesidad y salud pública.

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Manuela Belén Silveira

2007-01-01

Full Text Available El desarrollo de la genómica funcional en los próximos años condicionará cambios en el conocimiento teórico y la práctica clínica de la nutrición. La posibilidad de determinar el perfil genético de un individuo (variaciones genéticas y modificaciones epigenéticas y de conseguir la integración de estos datos en una compleja red de interacciones metabólicas constituye un desafío sin precedentes en la nutrición humana. La aplicación práctica del conocimiento científico puro derivado de la nutrigenómica, en términos de prevención y tratamiento de la obesidad, la DM2 y las enfermedades cardiovasculares, y sus implicaciones en la salud pública, son en este momento todavía indeterminadas. La posibilidad de una intervención nutricional en periodos críticos del desarrollo y la capacidad de modificar la susceptibilidad genética a ciertas enfermedades a través de la alimentación es el gran reto de la nutrigenómica, más allá del diseño de dietas o alimentos funcionales “personalizados”.

Análise das variações anatômicas do canal da mandíbula encontradas em radiografias panorâmicas

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Yza Daniella Nunes Andrade

Full Text Available INTRODUÇÃO: No âmbito da clínica odontológica, o bloqueio do nervo alveolar inferior é o mais utilizado; todavia, diversos estudos têm mostrado as mais altas taxas de fracasso, as quais, normalmente, têm como motivo a falha na observação da posição, da forma e da anatomia dos nervos. Essas falhas decorrentes da variação anatômica do nervo alveolar inferior já vêm sendo estudadas na literatura, através de estudos com a análise de radiografias panorâmicas, como proposto neste estudo. OBJETIVO: O objetivo deste estudo foi verificar a ocorrência e a prevalência das variações anatômicas, bem como a correlação das variações do canal da mandíbula com lado e sexo, que podem ocorrer no canal mandibular, por meio de radiografias panorâmicas de pacientes atendidos no Departamento de Odontologia da Universidade Federal de Sergipe (UFS. MATERIAL E MÉTODO: Foram analisadas 1.500 radiografias panorâmicas de pacientes atendidos pelo Departamento de Odontologia da Universidade Federal de Sergipe (UFS. Imagens radiográficas foram observadas sobre um negatoscópio, utilizando-se uma máscara preta ao redor das radiografias, em ambiente com luminosidade apropriada. RESULTADO: Neste estudo, foram observados 5,3% de bifurcações do canal mandibular; 47,5% de canais altos; 16,8% de canais intermediários; 27,1% de canais baixos, e 8,6% de canais com outras variações. CONCLUSÃO: Baseando-se na altura do canal mandibular, houve maior prevalência dos canais altos do que os demais nas mulheres, sendo que não houve diferenças entre os gêneros com relação aos demais tipos e lados afetados. Na classificação dos canais bífidos, não houve diferença estatisticamente significante entre homens e mulheres. Observou-se que a maior prevalência foi para canais sem bifurcação.

Bombacaceae endémicas del Perú

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Blanca León

2013-10-01

Full Text Available En este trabajo, la familia Bombacaceae es considerada aparte de las Malvaceae, con la cual se considera forma un grupo natural (ver Judd et al. 1997 y la página de internet de Angiosperm Phylogeny Group. En el Perú, las Bombacaceae incluyen 15 géneros y 56 especies (Brako & Zarucchi, 1993; Ulloa Ulloa et al., 2004, generalmente árboles. Siete especies en cinco géneros son endemismos del país. Estas especies endémicas ocupan principalmente las regiones Bosques Secos y Bosques Húmedos Amazónicos, entre los 1300 y 3000 m de altitud. Se aplicaron las categorías y criterios de la UICN a cuatro especies. Ninguna de las Bombacaceae endémicas está representada en el Sistema Nacional de Áreas Naturales Protegidas por el Estado.

Temas de Física para Ingeniería: Segundo principio de la termodinámica

OpenAIRE

Beléndez Vázquez, Augusto

1992-01-01

Acústica, fluidos y termodinámica: "Segundo principio de la termodinámica". Necesidad y enunciado del segundo principio. Rendimiento de las máquinas térmicas y frigoríficas. Ciclo de Carnot. Escala termodinámica de temperaturas. Entropía. Variaciones de entropía en procesos reversibles e irreversibles. Entropía y segundo principio.

Recubrimientos por PVD decorativos sobre cerámicas

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García, J. A.

2006-08-01

Full Text Available During the last years PVD coatings has been used for decorative purposes on ceramics and other substrates. Standards layers like TiN, CrN, TiCN, etc, give us the possibly of obtaining a wide range of colours, with a good mechanical, chemical properties. This paper gathers the works carried out in the Center of Advance Surface engineering of AIN during the three last years in the field of the decorative coatings. Different layer have been deposited by means of a METAPLAS 232 PVD equipment. A complete chemical and mechanical characterisation have been carried out on the different deposited layers like ultramicroindentation, scratch tests, wear resistance and GDOES.

En los últimos años se ha venido estudiado la aplicabilidad de las técnicas de depósitos mediante métodos físicos en fase vapor (PVD, para la realización de recubrimientos sobre cerámicas y otros substratos con fines decorativos. Los recubrimientos estándar por PVD como el TiN, CrN, TiCN, etc, ofrecen la posibilidad de conseguir acabados de apariencia metálica, de una amplia gama de colores, y con buenas propiedades mecánicas y químicas, como resistencia a la abrasión, estabilidad térmica, o resistencia a la corrosión. En este trabajo se recogen las experiencias realizadas en el recubrimiento y caracterización de cerámicas decorativas, durante los tres últimos años, en el Centro de Ingeniería de Superficies de la Asociación de la Industria Navarra. Los distintos tipos de recubrimientos se han realizado mediante un equipo de PVD modelo METAPLAS 232, con seis evaporadores de arco eléctrico y sistema de limpieza iónica patentado AEGD. Los recubrimientos han sido caracterizados, tanto química como mecánicamente, empleando las más modernas técnicas tribológicas (ultramicrodureza, scrascth tests, resistencia al desgaste... y espectroscópicas óptica por descarga luminiscente (GDOES. Los resultados obtenidos muestran que las técnicas de PVD son una

Sumérgete en la Bioquímica

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Josep M. Fernández Novell

2013-11-01

Full Text Available Hace ya dos años que el Departamento de Bioquímica y Biología Molecular de la Universidad de Barcelona con la colaboración de la SEBBM viene realizando anualmente unas sesiones prácticas de Bioquímica “Sumérgete en la Bioquímica”. Sesiones de mañana o de tarde dirigidas a los jóvenes de tercero y cuarto de la Enseñanza Secundaria Obligatoria (ESO. Estos jóvenes han recibido una información exhaustiva sobre qué es y de qué trata la Bioquímica, al mismo tiempo, han realizado una serie de experimentos en el laboratorio. En éstos, además de aprender las normas de seguridad, cómo utilizar el material volumétrico y las pipetas automáticas, han experimentado sobre: la obtención de ADN de vegetales, cómo medir la concentración de glucosa o de proteína de una muestra utilizando un espectrofotómetro, la producción de una proteína como la GFP en bacterias y las condiciones de precipitación de la caseína de la leche. También, desde Internet, han trabajado sobre cómo extraer el ADN humano y cómo clonar un ratón. Al finalizar cada sesión se recogieron dos tipos de encuestas, una dirigida al alumnado y la otra al profesorado de secundaria para saber el grado de aceptación de dicha actividad. El resultado de unas y otras indica que para todos ellos han sido unas actividades muy apreciadas e interesantes que sirven para aumentar el interés de los estudiantes hacia las ciencias y hacia la Bioquímica en particular. Esta experiencia se ha desarrollado en los laboratorios del Departamento de Bioquímica y Biología Molecular de la UB durante dos semanas entre el mes de Enero y el de Febrero época en que no están ocupados por la enseñanza habitual del Departamento. Este último curso han participado más de 750 estudiantes, la demanda ha superado nuestras previsiones obligándonos a preparar una tercera semana para el curso 2013-2014.

Nickel oxide crystalline nano flakes: synthesis, characterization and their use as anode in lithium-ion batteries

Science.gov (United States)

Ahmadi, Majid; Younesi, Reza; Vegge, Tejs; J-F Guinel, Maxime

2014-04-01

Nickel oxide crystalline nano flakes (NONFs)—only about 10 nm wide—were produced using a simple and inexpensive chemistry method followed by a short annealing in ambient air. In a first step, Ni(OH)2 sheets were synthesized by adding sodium hydroxide (NaOH) drop-wise in a Ni(NO3)2 aqueous solution that was then sonicated for up to 60 min, washed and vigorously stirred overnight in deionized water. In a second step, the products of this reaction were annealed in ambient air in the temperature range 285-450 °C producing the desired NONFs. The products were characterized using x-ray diffraction, scanning electron microscopy and high resolution transmission electron microscopy including electron diffraction and electron energy-loss spectroscopy. Electrochemical investigations showed that anodes made of these NONFs provided significantly higher discharge capacities (70 to 100% higher) compared to commercial nanometric NiO nanopowder used under the same conditions. Moreover, these NONFs had higher initial capacity retentions at both low and high current densities compared to the same NiO nanopowder.

Química recreativa i eines 2.0 per a la didàctica i divulgació de la química

OpenAIRE

Vieta i Corcoy, Pep Anton; Guillaumes, Laia; Güell, Mireia; Duran, Josep; Simon, Sílvia

2012-01-01

Que la societat sovint té una visió negativa de la química i que la recerca científica que té lloc a les universitats es percep com a llunyana per part de la població són fets coneguts. En aquest article, fruit de la presentació feta per l'autor principal a la VII Trobada de Joves Investigadors dels Països Catalans, organitzada el febrer de 2012 per la Societat Catalana de Química (SCQ), es presenten diversos projectes duts a terme des de la Càtedra de Cultura Científica i Comunicació Digi...

La racionalidad económica y la secularización

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ANDRÉS BILBAO

1996-01-01

Full Text Available La racionalidad económica es uno de los principales rasgos de la modernidad. Esta racionalidad es, aparentemente, resultado de la ruptura con la vieja superstición religiosa. Sin embargo, sus raíces están en ese mundo religioso, que cree haber superado. en este sentido, el proceso de secularización, del que nace la moderna racionalidad, no es más que la interiorización de los valores religiosos del cristianismo. La creencia de que el individuo, siguiendo sus propios intereses, da lugar a un mundo ordenado, es el rasgo característico de la racionalidad económica. Esta creencia tiene sus raíces en la doctrina cristiana en más de un mundo providencia. El desarrollo de la racionalidad económica no constituye a la superstición religiosa, sino que ella misma, como una nueva forma de superstición, se desarrolla en paralelo con ella.

Catalizadores Organometálicos en la Industria Química

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Alfonso Enrique Ramírez Sanabria

2015-10-01

Full Text Available Los procesos catalíticos son cada vez más importantes en la industria. Gran número de productos químicos incluyen dentro de su producción reacciones catalizadas. La catálisis se entiende como un proceso por el cual se aumenta la velocidad de una reacción química, debido a la participación de una especie química denominada catalizador. El presente trabajo recopila cinco procesos industriales en los cuales son empleados catalizadores organometálicos en fase homogénea. Busca resaltar la importancia que tienen los complejosorganometálicos como catalizadores, para la industria de química fina y farmacéutica. Se detallan aspectos mecanísticos en los que se puede ver el papel del centro metálico en las propiedades catalíticas del sistema, así como en la estructura del producto final.

Vida académica de la facultad

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Facultad de Medicina Revista

1999-10-01

Full Text Available Distinciones académicas / Novedades docentes / Libro' 'Manual de Rehabilitación Médica" / Texto de Obstetricia y Perinatología / xv Curso Anual Medicina Interna / Libros Publicados en la Facultad de Medicina Universidad Nacional De Colombia, 1999.

On the rare elements geochemistry in mica mega crystals from alkaline basaltoids of Southern Tien-Shane

International Nuclear Information System (INIS)

Mogarovskiy, V.V.; Sharapov, N.V.

1992-01-01

Rare elements without coherent in the mica and basalts are divided in 2 groups: First (K, Rb, Pb) in the first stage of meta soma tos are brought, and located in the mica. The second (Li, Cs, Sn) which brings after micas appearing, using in other minerals and without mineral location

An Experimental Study on Heat Conduction and Thermal Contact Resistance for the AlN Flake

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Huann-Ming Chou

2013-01-01

Full Text Available The electrical technology has been a fast development over the past decades. Moreover, the tendency of microelements and dense division multiplex is significantly for the electrical industries. Therefore, the high thermal conductible and electrical insulating device will be popular and important. It is well known that AlN still maintains stablility in the high temperature. This is quite attractive for the research and development department. Moreover, the thermal conduct coefficient of AlN is several times larger than the others. Therefore, it has been thought to play an important role for the radiator of heat source in the future. Therefore, this paper is focused on the studies of heat conduction and thermal contact resistance between the AlN flake and the copper specimens. The heating temperatures and the contact pressures were selected as the experimental parameters. According to the experimental results, the materials are soft and the real contact areas between the interfaces significantly increase under higher temperatures. As a result, the thermal contact resistance significantly decreases and the heat transfer rate increases with increasing the heating temperature or the contact pressures.

Fabrication of TiO2 nanorod assembly grafted rGO (rGO@TiO2-NR) hybridized flake-like photocatalyst

Science.gov (United States)

Lv, Kangle; Fang, Shun; Si, Lingling; Xia, Yang; Ho, Wingkei; Li, Mei

2017-01-01

To efficiently separate the photo-generated electron-hole pairs of TiO2 hybrid, anatase TiO2 nanorod assembly grafted reduced graphene oxides (rGO@TiO2-NR) hybrid was successfully fabricated using potassium titanium oxalate (PTO) and graphene oxides (GO) as starting materials and diethylene glycol (DEG) as reductant. The effect of GO content on the structure and photocatalytic activity of rGO@TiO2-NR composite was systematically studied. Results show that, in the absence of GO, only TiO2 microsphere assembly is obtained from TiO2 nanorods. The presence of GO results in the formation of a flake-like TiO2-nanorod-assembled grafted rGO hybrid. The photocatalytic activity of rGO@TiO2-NR composite increases first and then decreases with increase in the amount of GO from 0 wt.% to 10 wt.%. The hybridized S4 sample prepared with 4 wt.% GO possesses the highest photocatalytic activity with a constant rate of 0.039 min-1 in the photocataytic degradation of Brilliant X-3B dye (X3B); this sample was enhanced more than three times when compared with pure TiO2 sample (0.012 min-1). The enhanced photocatalytic activity of the rGO@TiO2-NR hybrid was attributed to the strong interaction between TiO2 nanorods and rGO. The unique hierarchical structure of 1D nanorod assembly TiO2-rGO flakes facilitates the injection and transfer of photo-generated electrons from TiO2 to graphene, thus retarding the recombination of electron-hole pairs and enhancing the photocatalytic activity. The enlarged BET surface areas, not only increasing the number of active sites, but also facilitating the adsorption of the dye, and improved light-harvesting ability also contribute to the enhanced photoreactivity of rGO@TiO2-NR hybrid.

Influence of the nonexchangeable potassium of mica on radiocesium uptake by paddy rice

International Nuclear Information System (INIS)

Eguchi, Tetsuya; Ohta, Takeshi; Ishikawa, Tetsuya; Matsunami, Hisaya; Takahashi, Yoshihiko; Kubo, Katashi; Yamaguchi, Noriko; Kihou, Nobuharu; Shinano, Takuro

2015-01-01

A pot cultivation experiment was conducted to elucidate the influence of the nonexchangeable potassium (K) of mica on radiocesium ( 137 Cs) uptake by paddy rice (Oryza sativa L. cv. Koshihikari), and to evaluate the potential of mica application as a countermeasure to reduce radiocesium transfer from soil to paddy rice. The increase in the exchangeable K concentrations of soils, measured before planting, due to mica (muscovite, biotite, and phlogopite) application was negligible. However, in trioctahedral mica (biotite and phlogopite)-treated soil, the release of nonexchangeable K from the mica interlayer maintained the soil-solution K at a higher level during the growing season in comparison to the control, and consequently decreased the 137 Cs transfer factor for brown rice (TF). The sodium tetraphenylboron (TPB)-extractable K concentration of the soils, measured before planting, was strongly negatively correlated with the TF, whereas the exchangeable K concentration of the soils, also measured before planting, was not correlated with the TF. Therefore, we conclude that TPB-extractable K is more reliable than exchangeable K as a basis of fertilizer recommendations for radiocesium-contaminated paddy fields. Phlogopite-treated soils exhibited higher TPB-extractable K concentrations and lower TF values than biotite-treated soils. We thus conclude that phlogopite application is an effective countermeasure to reduce radiocesium uptake in paddy rice. - Highlights: • Nonexchangeable K of added trioctahedral mica decreased 137 Cs uptake by paddy rice. • TPB-extractable K would be a more reliable indicator than exchangeable K. • Phlogopite would be a good amendment for radiocesium-contaminated paddy fields

Growth of highly textured SnS on mica using an SnSe buffer layer

International Nuclear Information System (INIS)

Wang, S.F.; Fong, W.K.; Wang, W.; Surya, C.

2014-01-01

We report the growth of SnS thin films on mica substrates by molecular beam epitaxy. Excellent 2D layered structure and strong (001) texture were observed with a record low rocking curve full width at half maximum of ∼ 0.101° for the SnS(004) diffraction. An interface model is used to investigate the nucleation of SnS on mica which indicates the co-existence of six pairs of lateral growth orientations and is in excellent agreement with the experimental Φ-scan measurements indicating 12 peaks separated by 30° from each other. To control the lateral growth of the SnS epilayers we investigate the utilization of a thin SnSe buffer layer deposited on the mica substrate prior to the growth of the SnS thin film. The excellent lattice match between SnSe and mica enhances the alignment of the nucleation of SnS and suppresses the minor lateral orientations along the mica[110] direction and its orthogonal axis. Detailed low-frequency noise measurement was performed to characterize the trap density in the films and our results clearly demonstrate substantial reduction in the density of the localized states in the SnS epilayer with the use of an SnSe buffer layer. - Highlights: • A record low rocking curve FWHM for deposited SnS on mica • Investigation of the nucleation of SnS on mica using the interface model • Investigation of nucleation mechanism by phi-scan measurement • Grain boundary formation from crystallites of various nucleation orientations • Suppression of nucleation orientations using an SnSe buffer layer

mica – music information center austria

OpenAIRE

2010-01-01

1994 wurde das österreichische Musikinformationszentrum (mica) im Auftrag des österreichischen Bundesministers für Unterricht und Kunst (Rudolf Scholten) von den Bundeskuratoren für Musik (L. Knessl, Christian Scheib) gegründet (Geschäftsführer 1994–99 Matthias Finkentey, 1999–09 Peter Rantasa, ab 2009 Sabine Reiter).

Temas de Física para Ingeniería: Dinámica del punto material

OpenAIRE

Beléndez, Augusto; Pastor Antón, Carlos; Bernabeu, Guillermo

1988-01-01

Apuntes de Mecánica: "Dinámica del punto material". Introducción, dinámica del punto. Fuerzas en la naturaleza. Sistemas de referencia. Leyes de Newton. Fuerzas de rozamiento. Ley de la gravitación universal. Aplicación de las leyes de Newton a la resolución de problemas de dinámica. Momento lineal y conservación. Redefinición de fuerza. Momento angular y conservación, fuerzas centrales. Impulso mecánico.

Aprendiendo química con golosinas

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José Manuel Rodríguez Rodríguez

2011-01-01

Full Text Available Las golosinas (caramelos, chicles, nubes, palotes, papas fritas, etc. nos gustan a casi todos y gozan de una imagen positiva, a pesar de sus efectos secundarios si no se consumen con moderación. Aprovechándonos de esa buena imagen y de la gran variedad de golosinas que existen en el mercado, hemos diseñado una serie de experimentos con los que podemos explicar distintos tipos de reacciones químicas (ácido-base, oxidación reducción, endotérmicas¿, la actuación de un indicador e, incluso, podemos comparar cantidades de vitamina C. En todas las actividades se persigue explicar algún aspecto de la Química que, en general, el público desconoce, captando su atención, por ejemplo, mediante cambios de color espectaculares y con las golosinas como protagonistas. Así mismo, estas experiencias pueden emplearse como recursos didácticos para alumnos de 4º E.S.O. y Bachillerato, apoyando los contenidos teóricos del currículum.

Polycrystalline Nd{sub 2}Fe{sub 14}B/α-Fe nanocomposite flakes with a sub-micro/nanometre thickness prepared by surfactant-assisted high-energy ball milling

Energy Technology Data Exchange (ETDEWEB)

Tang, Xin, E-mail: tangshincn@gmail.com [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Chen, Xi [Mechanical and Electrical Engineering College, Xinxiang University, No. 192, Jinsui Road, Xinxiang, Henan 453003 (China); Chen, Renjie; Yan, Aru [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)

2015-09-25

Highlights: • Nd{sub 2}Fe{sub 14}B/α-Fe flakes are formed by peeling along preferential planes. • (0 0 l) planes are found to be preferential cleavage planes. • Magnetic properties degrade with increasing ball milling time. • Anisotropic nanocomposite magnets are fabricated. - Abstract: A surfactant-assisted high-energy ball milling technique was employed to synthesize Nd{sub 2}Fe{sub 14}B/α-Fe nanoparticles and nanoflakes from melt-spun nanocrystalline powders. The microstructure evolution in ball milling process was investigated. In the beginning stage (0–4 h) of ball milling, raw powders were crushed into micrometre-sized particles. While flakes were mainly formed by reducing thickness of particles via peeling layer by layer along preferential planes in the late stage (8–16 h). The selected area electron diffraction and high-resolution transmission electron microscopy images show that preferential cleavage planes are basal planes. With ball milling proceeding, more and more defects were induced by ball milling. As a result, the coercivity and remanence decreased to 1.6 kOe and 3.2 kGs, respectively. After 16 h ball milling, the exchange decoupling occurred due to severe amorphorization. A weakly-textured nanocomposite magnet was fabricated after 12 h ball milling and the anisotropy in magnetic properties can be further improved by employing settling down process to select particle size and aligning particles in external field.

Experiments on the incorporation of concentrated solutions of fission products in glasses and micas; Essais d'incorporation de solutions concentrees de produits de fission dans des verres et des micas

Energy Technology Data Exchange (ETDEWEB)

Bonniaud, R; Cohen, P; Sombret, C [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1958-07-01

1) The plants designed for extracting the plutonium of the G1, G2, G3 reactors fuel rods will produce extremely concentrated tions of fission products. 2) Let us consider a synthetic solution of the 'G2' type: (2N NO{sub 3}H - 2,25 meq/cm{sup 3} AI{sup +++} - 5.10{sup -3} {sup 134}Cs - {sup 137}Cs tracer). We made various glasses and micas by adding and mixing the necessary adjuvants and baking (900 to 1400 deg. C) in a graphite crucible. 3) The products obtained had either the shape of a cylindrical pellet or were reduced into a fine powder. They were mixed with 300 cm{sup 3} of synthetic sea water during variable periods of time in order to study leaching of the activity. 4) Experiments were first carried on caesium because of its solubility. 5) Fabrication of micas on a large scale sets many technological problems more difficult to solve (1400 deg. C) than in the case of glasses (1000 deg. C). A comparative study on both micas and glasses showed that leaching of activity was more important in the micas. (author)Fren. [French] 1) La mise en service de l'Usine d'Extraction du Plutonium destinee en particulier au traitement des barres de combustibles de G1, G2, G3 fournira des solutions residuaires concentrees de produits de fission. 2) Partant d'une solution synthetique 'G2': (2N NO{sub 3}H - 2,25meq/cm{sup 3} AI{sup +++} - 5.10{sup -3} {sup 134}Cs - {sup 137}Cs traceur) nous avens realise differents verres et micas apres adduction et melange des adjuvants necessaires suivis de cuisson (900 a 1400 deg. C) dans un creuset de graphite. 3) Les produits obtenus ont ete, soit sous forme d'eprouvette cylindrique, soit sous forme de poudre finement broyee, mis en contact et agites avec 300 cm{sup 3} d'eau de mer synthetique, durant des temps varies pour etudier la retention de l'activite. 4) Le cesium a ete choisi pour ces essais a cause de sa solubilite. 5) La fabrication de micas a grande echelle pose des problemes technologiques plus difficiles (1400 deg. C) a

EL CONGRESO DE KARLSRUHE: PASO DEFINITIVO HACIA LA QUÍMICA MODERNA

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Ramón Cid Manzano

2009-01-01

Full Text Available Estamos celebrando en este año 2009 el 140 aniversario de la publicación de la primera tabla periódica y el 90 aniversario de la creación del IUPAC. Ambos acontecimientos se relacionan directamente con el congreso de Karlsruhe llevado a cabo en esa ciudad alemana en 1860. Este congreso fué convocado para que los químicos europeos pudieran discutir sobre asuntos muy controvertidos, como la naturaleza atómica de la materia, la nomenclatura química y los pesos atómicos. El objetivo de este artículo es proporcionar a los lectores algunos datos sobre este congreso para entender mejor cómo la tabla periódica fue desarrollada y cómo la química se convirtió en una ciencia moderna.

El sector inmobiliario y las crisis económicas

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Antonio Daher

2013-09-01

Full Text Available La creciente urbanización de la economía y la doble concentración -económica y territorial- de los sectores inmobiliario y financiero en las metrópolis, fundamentan la relación entre los ciclos inmobiliarios y las crisis económicas detonadas por sus burbujas, la alta incidencia macroeconómica del sector inmobiliario y su rol articulador entre el sector financiero y la economía real. Antes de la última crisis (2008, las instituciones financieras y fondos de inversión inmobiliaria transnacionales encontraron en la financiarización y titulización una vía eficaz para su diversificación geográfica y distribución del riesgo hipotecario. Fue también la vía expedita del contagio de una crisis con ubicuidad financiera, aunque no social ni territorial. Las hipotecas subprime fueron para las minorías marginadas en los barrios con más hispanos, negros, inmigrantes y pobres: la vivienda social estadounidense, financiarizada, "inmobiliarizó" al sector financiero y desfinanciarizó la banca internacional, en una crisis global con dramáticas consecuencias sociales y políticas.

MORFOMETRÍA, HIDRODINÁMICA Y FÍSICO-QUÍMICA DEL AGUA DE LA LAGUNA DE CHAUTENGO, GUERRERO, MÉXICO

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Rendón-Dircio JA

2012-02-01

Full Text Available Se realizó un estudio del comportamiento de las variables morfométricas, batimétricas, hidrodinámicas y físico-químicas de la Laguna de Chautengo, Guerrero, a partir de fotografías aéreas y trabajo de campo con muestreos bimensuales de variables morfométricas, hidrodinámicas y físico-químicas del agua. Los resultados indicaron que la laguna presentó marcadas variaciones anuales en su morfometría y batimetría. El área máxima estimada fue de 29.6 km2. La barra de la laguna es recta y está colonizada en un 36.8 % por comunidades de manglar, tiene una longitud de 10 km y una anchura media de 0.52 km. Las tres islas que presenta la laguna se ubican cerca de la desembocadura y tienen un área de 83,000, 3,680 y 61,440 m2 respectivamente. La variación vertical de la columna de agua fluctuó entre 6 y 12 cm diarios, presentándose el máximo nivel a las 18:00 y 0:00 h y el mínimo a las 6:00 h. Las corrientes presentaron un valor promedio de velocidad de 1.97 m/min. La temperatura media anual fue de 29.8 oC, con una variación entre la superficie y el fondo de 0.23 oC; la salinidad varió de 0.7 a 38 ‰; el oxígeno disuelto se registró en promedio en 4.71 mg/L, existiendo una diferencia del 8.7 % entre la superficie. La laguna presenta características de un cuerpo de agua somero y tropical en un proceso avanzado de evolución, pero con condiciones adecuadas para el desarrollo de la fauna y flora acuática. Este estudio servirá de base para el diseño de un plan de manejo sostenible de las pesquerías y acuicultura de la Laguna de Chautengo.

Liberalização financeira, performance econômica e estabilidade macroeconômica no Brasil: uma avaliação do período 1994-2007

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Luiz Fernando de Paula

2013-05-01

Full Text Available Este artigo objetiva avaliar a relação entre liberalização da conta capital, performance econômica e estabilidade macroeconômica no Brasil. Para tanto, além de uma revisão da literatura, o artigo realiza uma avaliação em-pírica dos efeitos da liberalização financeira no Brasil sobre um conjunto de variáveis macroeconômicas com o uso da metodologia VAR, utilizando, para tanto, dois modelos: um com um índice de jure de liberalização financeira (ILF, e outro com um índice de facto de integração financeira (IIF. Procura-se, no primeiro caso, avaliar a hipótese de que a liberalização financeira resulta em redução no risco país e, consequentemente, na taxa de juros doméstica; no segundo caso, avalia-se a hipótese de que a liberalização financeira tem impacto positivo sobre o crescimento econômico e a estabilidade macroeconômica vis-à-vis à hipótese dos críticos da liberalização financeira de que esta gera efeitos instabilizadores em países em desenvolvimento.

Indiscernibilidade e identidade em química: aspectos filosóficos e formais

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Jaison Schinaider

2014-06-01

Full Text Available Neste artigo tratamos, de um ponto de vista formal e filosófico, com alguns conceitos que fazem parte da química usual. As teorias da química, e seus conceitos, normalmente são apresentadas de um ponto de vista informal (não axiomatizada, e isso pode trazer dificuldades filosóficas (embora a química propriamente - bem como também as outras disciplinas da ciência aplicada - pareçam não sofrer qualquer restrição quanto a isso. Aqui estaremos ocupados em um aspecto parti-cu-lar, que diz respeito à indiscernibilidade de alguns objetos básicos da química, tais como átomos, moléculas, bem como de seus componentes. Começamos com uma visão geral da identidade destes compostos e seus componentes a partir de uma perspectiva filosófica e, em seguida, mostramos em que sentido o conceito de identidade dos compostos químicos é problemático em relação ao conceito correspondente de identidade na lógica e matemática clássicas (que, como em geral é suposto, estão 'alicerçando' as teorias químicas. Argumentamos que, por um lado, a química parece supor que esses objetos básicos precisam ser 'idênticos' (indistinguíveis uns aos outros (como enfatizado há muito tempo por John Dalton, como veremos. Por outro lado, do ponto de vista formal, se a lógica subjacente à teoria atômica for a lógica clássica (que também é pano de fundo da matemática padrão, coisas idênticas devem ser a mesma coisa e logo 'colapsar' em apenas uma (e este não é o caso em química, uma vez que temos uma enorme quantidade de átomos e moléculas semelhantes, mas não apenas um. Esta aparente contradição pode ser tratada de várias perspectivas e, aqui, propomos o uso de uma teoria de conjuntos não-clássica (a saber, a teoria de quase-conjuntos para alicerçar uma formulação axiomática de certas teoria químicas, mostrando como essa diferente base matemática pode nos levar a uma visão que está mais perto da química em si. Como esta

Química de Heterociclos

OpenAIRE

Collado, Daniel

2014-01-01

Heterociclos aromáticos con cinco miembros. Pirrol, furano y tiofeno: propiedades. Sustitución electrofílica aromática. Reacciones de los sustituyentes alquílicos. Sustitución nucleofílica. Radicales y carbenos, aperturas de anillo. Síntesis. Capítulo segundo del temario del segundo bloque de la asignatura Ampliación de Química Orgánica Avanzada. Heterociclos aromáticos de cinco miembros.

Cerámicas de circona para aplicaciones biomédicas

OpenAIRE

Delgado García-Menocal, José Angel; Morejón, L.; Martínez, S.; Gil, F. X. (Francesc Xavier)

2003-01-01

Se tratan los aspectos mas significativos de distintos biomateriales empleados para la sustitución del tejido óseo pero haciendo énfasis en las cerámicas de óxido de zirconio (circonas). Se destacan las características de las cerámicas de circona que lo convierten en un material muy atractivo por sus excelentes propiedades mecánicas, en particular su elevada tenacidad a la fractura relacionada con la transformación martensítica que se produce cuando el material es sometido a un...

Characterization of Deposited Platinum Contacts onto Discrete Graphene Flakes for Electrical Devices

KAUST Repository

Holguin Lerma, Jorge A.

2016-05-03

For years, electron beam induced deposition has been used to fabricate electrical contacts for micro and nanostructures. The role of the contact resistance is key to achieve high performance and efficiency in electrical devices. The present thesis reports on the electrical, structural and chemical characterization of electron beam deposited platinum electrodes that are exposed to different steps of thermal annealing and how they are used in four-probe devices of ultrathin graphite (uG) flakes (<100nm thickness). The device integration of liquid phase exfoliated uG is demonstrated, and its performance compared to devices made with analogous mechanically exfoliated uG. For both devices, similar contact resistances of ~2kΩ were obtained. The electrical measurements confirm a 99.5% reduction in contact resistance after vacuum thermal annealing at 300 °C. Parallel to this, Raman characterization confirms the formation of a nanocrystalline carbon structure over the electrode. While this could suggest an enhancement of the electrical transport in the device, an additional thermal annealing step in air at 300 °C, promoted the oxidation and removal of the carbon shell and confirmed that the contact resistance remained the same. Overall this shows that the carbon shell along the electrode has no significant role in the contact resistance. Finally, the challenges based on topographical analysis of the deposited electrodes are discussed. Reduction of the electrode’s height down to one-third of the initial value, increased surface roughness, formation of voids along the electrodes and the onset of platinum nanoparticles near the area of deposition, represent a challenge for future work.

Van der Waals epitaxy and photoresponse of hexagonal tellurium nanoplates on flexible mica sheets.

Science.gov (United States)

Wang, Qisheng; Safdar, Muhammad; Xu, Kai; Mirza, Misbah; Wang, Zhenxing; He, Jun

2014-07-22

Van der Waals epitaxy (vdWE) is of great interest due to its extensive applications in the synthesis of ultrathin two-dimensional (2D) layered materials. However, vdWE of nonlayered functional materials is still not very well documented. Here, although tellurium has a strong tendency to grow into one-dimensional nanoarchitecture due to its chain-like structure, we successfully realize 2D hexagonal tellurium nanoplates on flexible mica sheets via vdWE. Chemically inert mica surface is found to be crucial for the lateral growth of hexagonal tellurium nanoplates since it (1) facilitates the migration of tellurium adatoms along mica surface and (2) allows a large lattice mismatch. Furthermore, 2D tellurium hexagonal nanoplates-based photodetectors are in situ fabricated on flexible mica sheets. Efficient photoresponse is obtained even after bending the device for 100 times, indicating 2D tellurium hexagonal nanoplates-based photodetectors on mica sheets have a great application potential in flexible and wearable optoelectronic devices. We believe the fundamental understanding of vdWE effect on the growth of 2D tellurium hexagonal nanoplate can pave the way toward leveraging vdWE as a useful channel to realize the 2D geometry of other nonlayered materials.

La superación en gestión académica del directivo universitario

Directory of Open Access Journals (Sweden)

Vicenta Aveiga Macay

2013-12-01

Full Text Available Se planteó como objetivo sistematizar los fundamentos teóricos que sustentan el proceso de superación a directivos universitarios para la gestión académica. Se utilizó métodos del nivel teórico y empírico como el histórico lógico, analítico-sintético, el análisis documental, la observación, el inventario de dificultades, cuestionarios, entrevistas, los cuales posibilitaron caracterizar epistemológicamente el proceso de superación a directivos universitarios con énfasis en la gestión académica, arribar a nuevos conceptos, y distinguir aspectos significativos de la superación a directivos en gestión académica. PALABRAS CLAVES: Directivos, gestión académica, proceso formativo, superación.

Evolución hacia la cerámica fotovoltaica

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Sánchez-Muñoz, L.

2011-02-01

Full Text Available Nowadays there are two types of ceramic materials, i.e. traditional and advanced. The origin and development of the first one occurred before the revolutionary changes in Science and Technology of the nineteenth century, while the second one is its direct consequence. The traditional ceramics, which are related primarily to elementary human needs, in particular its constructions, is very homogeneous with respect to their formulations, being their diversity mainly linked to the decorative aspects of one surface. Advanced ceramics are characterized by a wide variety of materials with specific physical and chemical responses to radiation and electromagnetic fields, where major economic benefits are mainly related to secondary human needs such as telecommunications. As a result of the current global crisis, traditional buildings could be rehabilitated and/or replaced by energy efficient buildings, also called zero-energy buildings. In them there is a balance between energy consumed and produced “in situ”, and also using environmentally friendly materials. The direct consequence of this trend will be the evolution of ceramics by partial hybridization of its two ancestors, with special importance of semiconductor compounds, to the production of electrical energy as the basic objective, in this work called photovoltaic ceramics.

Actualmente se distinguen dos tipos de cerámica, una tradicional y otra avanzada. El origen y desarrollo de la primera es anterior a los cambios revolucionarios en Ciencia y Tecnológica del siglo XIX, mientras que la segunda es su consecuencia directa. La cerámica tradicional, que está relacionada sobre todo con las necesidades humanas primarias y en particular a sus construcciones, es muy homogénea respecto a sus formulaciones, estando su diversidad ligada principalmente a los aspectos decorativos de una de sus superficies. La cerámica avanzada se caracteriza por una gran diversidad de materiales con

Dinámica fisicoquímica de las aguas de un sistema de planicies inundables tropicales

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Yimmy Montoya M

2013-01-01

Full Text Available Se estudió el cambio de algunas variables fisicoquímicas en el agua de siete caños y siete ciénagas pertenecientes a la zona de planos de inundación de Ayapel en nueve muestreos durante el periodo 2006-2009. El valor medio de la conductividad eléctrica en la ciénaga es tres veces inferior al valor medio de las ciénagas de la región. 100 μS/cm puede considerarse como discriminante entre ciénagas con valores inferiores y los caños con valores superiores. No hubo relación entre la transparencia y la concentración de pigmentos fotosintéticos, lo que podría considerarse como indicador de un nivel de estado trófico bajo del sistema. A nivel temporal todas las formas de nutrientes evaluadas presentaron diferencias lo que indica la importancia del efecto del pulso de inundación a través del ciclo hidrológico. Con la disminución de la columna de agua en época de estiaje, se evidenció un aumento de las concentraciones de nitrógeno, las cuales se ven favorecidas por la resuspensión de material del fondo de la ciénaga. La concentración de fósforo es más sensible a la variación espacial, ya que el ciclo de este nutriente estuvo asociado a los sedimentos y a la composición del suelo de cada microcuenca. Se encontró que para una misma fase del pulso en ciclos sucesivos, se registran diferencias en la dinámica del sistema, por lo que el momento hidrológico en el que se realiza el muestreo es el factor principal en el comportamiento de las condiciones fisicoquímicas del sistema.

La contaminación Química

OpenAIRE

Jimbo G., Marcelo

2003-01-01

La contaminación química de la leche se puede verificar mediante cuatro vías: a. Detergentes y desinfectantes usados en las operaciones de lavado. b.Antielmínticos. c. Insecticidas y anticriptogámicos usados en agricultura. d. Elementos radioactivos, sustancias dicersas, metales.

Influence of the nonexchangeable potassium of mica on radiocesium uptake by paddy rice.

Science.gov (United States)

Eguchi, Tetsuya; Ohta, Takeshi; Ishikawa, Tetsuya; Matsunami, Hisaya; Takahashi, Yoshihiko; Kubo, Katashi; Yamaguchi, Noriko; Kihou, Nobuharu; Shinano, Takuro

2015-09-01

A pot cultivation experiment was conducted to elucidate the influence of the nonexchangeable potassium (K) of mica on radiocesium ((137)Cs) uptake by paddy rice (Oryza sativa L. cv. Koshihikari), and to evaluate the potential of mica application as a countermeasure to reduce radiocesium transfer from soil to paddy rice. The increase in the exchangeable K concentrations of soils, measured before planting, due to mica (muscovite, biotite, and phlogopite) application was negligible. However, in trioctahedral mica (biotite and phlogopite)-treated soil, the release of nonexchangeable K from the mica interlayer maintained the soil-solution K at a higher level during the growing season in comparison to the control, and consequently decreased the (137)Cs transfer factor for brown rice (TF). The sodium tetraphenylboron (TPB)-extractable K concentration of the soils, measured before planting, was strongly negatively correlated with the TF, whereas the exchangeable K concentration of the soils, also measured before planting, was not correlated with the TF. Therefore, we conclude that TPB-extractable K is more reliable than exchangeable K as a basis of fertilizer recommendations for radiocesium-contaminated paddy fields. Phlogopite-treated soils exhibited higher TPB-extractable K concentrations and lower TF values than biotite-treated soils. We thus conclude that phlogopite application is an effective countermeasure to reduce radiocesium uptake in paddy rice. Copyright © 2015 Elsevier Ltd. All rights reserved.

Compreensão econômica de estudantes entre 10 e 15 anos

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Sonia Bessa

2014-08-01

Full Text Available Nos últimos 50 anos, ocorreram significativas mudanças sociais, culturais, políticas, econômicas e tecnológicas que afetam o comportamento de pré-adolescentes e jovens. Essa faixa etária necessita de investigações sobre sua compreensão do mundo econômico e o papel da família no processo de socialização econômica. Por isso, a presente pesquisa tem por objetivo principal caracterizar a compreensão econômica de 830 estudantes de 10 a 15 anos de diferentes níveis socioeconômicos, moradores da cidade de São Paulo. O instrumento utilizado foi o Teste de Alfabetização Econômica para crianças, TAE-N. Com abordagem qualitativa e quantitativa, utilizou-se o desenho descritivo-comparativo e correlacional. Apresenta-se a frequência das variáveis categóricas; valores de frequência absoluta, percentual; média e desvio-padrão; utilizou-se o coeficiente alfa de Cronbach; teste Qui-Quadrado. Para a comparação de medidas contínuas ou ordenáveis, valeu-se dos testes Mann-Whitney e Kruskal-Wallis. Os resultados demonstram uma socialização econômica insuficiente para lidar com as exigências do mundo econômico.

Mastocitosis sistémica: repercusión ósea

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Francisco R. Spivacow

2012-06-01

Full Text Available La mastocitosis sistémica es una enfermedad caracterizada por acumulación de mastocitos en varios órganos, de los cuales el más afectado es la piel. La repercusión ósea de esta enfermedad es poco frecuente y en general se la asocia al desarrollo de osteoporosis secundaria con o sin fracturas óseas. Se presentan tres pacientes con lesiones características en piel de mastocitosis y diferentes manifestaciones óseas; el primer caso es una mujer de 51 años en la que se observó una variante esclerosante muy poco frecuente, con densitometría ósea en valores normales-altos y aumento de la densidad ósea observada en varias vértebras por radiografías. Una punción-biopsia de cresta ilíaca confirmó el compromiso óseo de su enfermedad de base. El segundo caso fue una mujer de 57 años que mostró signos característicos de mastocitosis sistémica con diarreas, gastritis, flushes y reacciones cutáneas particulares ante exposición a alérgenos. Se observó además grave disminución de la densidad mineral ósea tanto en columna lumbar como en cuello de fémur con parámetros bioquímicos de aumento de la resorción ósea, por lo que fue necesario tratarla con bisfosfonatos. La tercera paciente, de 67 años de edad, presentó varias fracturas vertebrales, con densitometría ósea levemente disminuida. En esta última paciente se constató una hiperplaquetosis con diagnóstico histológico de trombocitemia esencial, cuadro que suele asociarse a la mastocitosis sistémica. En definitiva, se presentan y discuten tres variantes óseas diferentes de mastocitosis sistémica.

Dinâmica molecular ab initio:aplicações ao estudo de propriedades electrónicas de sistemas moleculares

OpenAIRE

Martiniano, Hugo Filipe de Mesquita Costa, 1978-

2013-01-01

Tese de doutoramento, Química (Química-Física), Universidade de Lisboa, Faculdade de Ciências, 2013 O método da dinâmica molecular ab initio exibe vantagens significativas para o estudo da estrutura e propriedades electrónicas de sistemas moleculares complexos. No entanto, uma das suas desvantagens é o elevado custo computacional, quando comparado com os métodos de dinâmica molecular clássicos. Um dos modos de resolver este problema é adoptar uma abordagem sequencial, na qual a dinâmica é ...

Mesoporous-activated carbon prepared from chitosan flakes via single-step sodium hydroxide activation for the adsorption of methylene blue.

Science.gov (United States)

Marrakchi, F; Ahmed, M J; Khanday, W A; Asif, M; Hameed, B H

2017-05-01

In this work, mesoporous-activated carbon (CSAC) was prepared from chitosan flakes (CS) via single-step sodium hydroxide activation for the adsorption of methylene blue (MB). CSAC was prepared using different impregnation ratios of NaOH:CS (1:1, 2:1, 3:1, and 4:1) at 800°C for 90min. The adsorption performance of CSAC was evaluated for MB at different adsorption variables, such MB initial concentrations (25-400mg/L), solution pH (3-11), and temperature (30-50°C). The adsorption isotherm data of CSAC-MB were well fitted to Langmuir model with a maximum adsorption capacity 143.53mg/g at 50°C. Best representation of kinetic data was obtained by the pseudo-second order model. CSAC exhibited excellent adsorption uptake for MB and can potentially be used for other cationic dyes. Copyright © 2017 Elsevier B.V. All rights reserved.

Justicia epistémica y epistemologías del Sur

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Miguel Mandujano Estrada

2017-05-01

Full Text Available Realizaré, en este trabajo, una síntesis de la dimensión epistemológica de la obra de Boaventura de Sousa Santos. A partir de la idea de justicia e injusticia epistémica, reconstruiré la dimensión metodológica de su plataforma crítica, a saber, la ecología de saberes. Intentaré establecer la relación de la injusticia epistémica con el colonialismo y defender la particularidad descolonial de las prácticas inscritas en las epistemologías del Sur y el cosmopolitismo subalterno.

Interacciones sociales y explotación económica

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Andrés Montaña

2012-05-01

Full Text Available Planteo aquí un nuevo modelo de interacción social general basado en lasdotaciones de información, heurística y recursos de los agentes de una organización social. A partirde estas dotaciones se puede hacer una representación en un espacio social determinado en el quese desarrollan interacciones sociales. El modelo permite identificar la posición de un agente en elespacio social y hacer comparaciones interpersonales.A partir del modelo de interacción social general, planteo un modelo de explotación económica.Una autoridad desde este modelo de explotación puede establecer áreas de restricción para determinarla explotación económica de los agentes.El cálculo de las dotaciones y las combinaciones de éstas, pueden permitir a una autoridaddeterminar si existe o no explotación de unos agentes por otros, fijar categorías de explotación, eidentificar áreas de atención prioritarias. El modelo se podría constituir en una herramienta másapropiada para la identificación de la condición laboral o económica de los niños y niñas.

CARACTERIZACIÓN QUÍMICA Y CLASIFICACIÓN TAXONÓMICA DE ALGUNOS SUELOS CULTIVADOS CON BANANO EN LAS LLANURAS ALUVIALES DEL CARIBE DE COSTA RICA

Directory of Open Access Journals (Sweden)

Fulvio Arias

2010-01-01

Full Text Available Se realizó la caracterización morfológica, química y la clasificación taxonómica de algunos suelos cultivados con banano en las 11 cuencas hidrográficas que confluyen en las llanuras aluviales de la Vertiente Caribe de Costa Rica. Se identificaron 2 sectores con suelos que tienen propiedades morfológicas, químicas, y taxonómicas diferentes. En una zona, se encontraron principalmente Inceptisoles formados a partir de materiales fluvio-volcánicos con propiedades ándicas (Andic Eutrudepts, Aquandic Endoaquepts, Inceptisoles dístricos (Fluventic Dystrudepts y Andisoles (Typic Hapludands; caracterizados por presentar la mayoría buen drenaje, texturas medias (franco arenosa, franca, franca limosa, una suma de bases entre 10 y 19 cmol.l–1, una CIC entre 13 y 28 cmol.l–1 y carga permanente en la arcillas. En la otra zona, se encontraron principalmente Inceptisoles formados a partir de aluviones de origen sedimentario depositados por inundaciones frecuentes (Fluventic Endoaquepts, Dystric Fluventic Eutrudepts, Fluvaquentic Eutrudepts, Fluvaquentic Endoaquepts, con una suma de bases entre 18 y 46 cmol.l–1, una CIC entre 19 y 46 cmol.l–1, sin propiedades ándicas, texturas finas y moderadamente finas (franco arcillosa, franco arcillosa limosa, arcillosa, arcillosa limosa y con problemas de drenajes en algunos casos (Endoaquepts, Epiaquepts, Fluvaquentic. Geográficamente, estas zonas fueron separadas por la subcuenca formada por los ríos Vueltas-Silencio-Parismina, de forma que hacia el noroeste se encuentran suelos con influencia volcánica y fertilidad media, y hacia el sureste suelos sin influencia volcánica y de fertilidad alta.

La flexibilitat en els àcids nucleics: Un estudi de dinàmica molecular

OpenAIRE

Noy Freixa, Agnès

2008-01-01

[cat] L'estat de l'art de les simulacions de dinàmica molecular és utilitzat per estudiar l'estructura, dinàmica, propietats d'interacció molecular i flexibilitat dels dúplexs d'ADN i ARN en solució acuosa. Les nostres simulacions suggereixen que el concepte de flexibilitat, rigidesa i deformabilitat són molt més complexes del que habitualment es creu, i que per tant no és sempre veritat que l'ADN sigui més flexible que l'ARN. La dinàmica molecular és a més utilitzada per investigar les prop...

Flexibilitat en els àcids nucleics: Un estudi de dinàmica molecular, La

OpenAIRE

Noy Freixa, Agnès

2008-01-01

L'estat de l'art de les simulacions de dinàmica molecular és utilitzat per estudiar l'estructura, dinàmica, propietats d'interacció molecular i flexibilitat dels dúplexs d'ADN i ARN en solució acuosa. Les nostres simulacions suggereixen que el concepte de flexibilitat, rigidesa i deformabilitat són molt més complexes del que habitualment es creu, i que per tant no és sempre veritat que l'ADN sigui més flexible que l'ARN.La dinàmica molecular és a més utilitzada per investigar les propietats d...

ANÁLISE DINÂMICA DE ESTRUTURAS DE AÇO SUPORTES DE MÁQUINAS ROTATIVAS

OpenAIRE

FERRO, R. M.

2014-01-01

Uma análise dinâmica adequada é necessária para verificação de estruturas suportes de equipamentos mecânicos visando assegurar não somente o conforto humano dos usuários como também boas condições para o funcionamento dos equipamentos da estrutura. Em recentes estudos de dinâmica estrutural e dinâmica de equipamentos, verifica-se a dificuldade de realizar modelos reais de estruturas suportes de máquinas rotativas. Considerando que as duas áreas têm o estudo comum na análise das vibrações prod...

Zirconia toughened mica glass ceramics for dental restorations.

Science.gov (United States)

Gali, Sivaranjani; K, Ravikumar; Murthy, B V S; Basu, Bikramjit

2018-03-01

The objective of the present study is to understand the role of yttria stabilized zirconia (YSZ) in achieving the desired spectrum of clinically relevant mechanical properties (hardness, elastic modulus, fracture toughness and brittleness index) and chemical solubility of mica glass ceramics. The glass-zirconia mixtures with varying amounts of YSZ (0, 5, 10, 15 and 20wt.%) were ball milled, compacted and sintered to obtain pellets of glass ceramic-YSZ composites. Phase analysis was carried out using X-ray diffraction and microstructural characterization with SEM revealed the crystal morphology of the composites. Mechanical properties such as Vickers hardness, elastic modulus, indentation fracture toughness and chemical solubility were assessed. Phase analysis of sintered pellets of glass ceramic-YSZ composites revealed the characteristic peaks of fluorophlogopite (FPP) and tetragonal zirconia. Microstructural investigation showed plate and lath-like interlocking mica crystals with embedded zirconia. Vickers hardness of 9.2GPa, elastic modulus of 125GPa, indentation toughness of 3.6MPa·m 1/2 , and chemical solubility of 30μg/cm 2 (well below the permissible limit) were recorded with mica glass ceramics containing 20wt.% YSZ. An increase in hardness and toughness of the glass ceramic-YSZ composites with no compromise on their brittleness index and chemical solubility has been observed. Such spectrum of properties can be utilised for developing a machinable ceramic for low stress bearing inlays, onlays and veneers. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Simultaneous reduction and adsorption for immobilization of uranium from aqueous solution by nano-flake Fe-SC

Energy Technology Data Exchange (ETDEWEB)

Kong, Lingjun, E-mail: kongl_jun@163.com [School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 510275 (China); Guangdong Provincial Key Laboratory of radioactive contamination control and resources, Guangzhou University, Guangzhou, 510275 (China); Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou, 510275 (China); Zhu, Yuting; Wang, Min; Li, Zhixuan; Tan, Zhicong; Xu, Ruibin; Tang, Hongmei; Chang, Xiangyang [School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 510275 (China); Guangdong Provincial Key Laboratory of radioactive contamination control and resources, Guangzhou University, Guangzhou, 510275 (China); Xiong, Ya [Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou, 510275 (China); Chen, Diyun, E-mail: cdy@gzhu.edu.cn [School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 510275 (China); Guangdong Provincial Key Laboratory of radioactive contamination control and resources, Guangzhou University, Guangzhou, 510275 (China)

2016-12-15

Uranium containing radioactive wastewater is seriously hazardous to the natural environment if it is being discharged directly. Herein, nano-flake like Fe loaded sludge carbon (Fe-SC) is synthesized by carbothermal process from Fe-rich sludge waste and applied in the immobilization of uranium in aqueous. Batch isotherm and kinetic adsorption experiments are adopted to investigate the adsorption behavior of Fe-SC to uranium in aqueous. XPS analyses were conducted to evaluate the immobilized mechanism. It was found that the carbonized temperature played significant role in the characteristics and immobilization ability of the resulted Fe-SC. The Fe-SC-800 carbonized at 800 °C takes more advantageous ability in immobilization of uranium from aqueous than the commercial available AC and powder zero valent iron. The adsorption behavior could be fitted well with the Langmuir isotherm adsorption model and pseudo-second order model. The equilibrium adsorption amount and rate for Fe-SC-800 is high to 148.99 mg g{sup -1} and 0.015 g mg{sup -1} min{sup -1}, respectively. Both reductive precipitation and physical adsorption are the main mechanisms of immobilization of uranium from aqueous by Fe-SC-800.

Estudos ecológicos preliminares e caracterização química dos Cnidaria da costa noroeste portuguesa

OpenAIRE

Gadelha, Juliana Rodrigues

2007-01-01

O levantamento de recursos em espécies marinhas em Portugal ainda é incipiente, considerando que este domínio de investigação tem sido amplamente desenvolvido noutros pontos do globo, pescas, química, bioquímica e farmacologia de organismos marinhos, de modo a obter informações sobre a química de produtos naturais e ecologia química de organismos marinhos derivadas destes organismos. São de realçar a importância das defesas químicas para as relações ecológicas de predação, comp...

Exfoliated graphite with graphene flakes as potential candidates for TL dosimeters at high gamma doses.

Science.gov (United States)

Ortiz-Morales, A; López-González, E; Rueda-Morales, G; Ortega-Cervantez, G; Ortiz-Lopez, J

2018-06-06

Graphite powder (GP) subjected to microwave radiation (MWG) results in exfoliation of graphite particles into few-layered graphene flakes (GF) intermixed with partially exfoliated graphite particles (PEG). Characterization of MWG by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Raman spectroscopy reveal few-layer GF with sizes ranging from 0.2 to 5 µm. Raman D, G, and 2D (G') bands characteristic of graphitic structures include evidence of the presence of bilayered graphene. The thermoluminescent (TL) dosimetric properties of MWG are evaluated and can be characterized as a gamma-ray sensitive and dose-resistant material with kinetic parameters (activation energy for the main peak located at 400 and 408 K is 0.69 and 0.72 eV) and threshold dose (~1 kGy and 5 kGy respectively). MWG is a low-Z material (Z eff = 6) with a wide linear range of TL dose-response (0.170-2.5 kGy) tested at doses in the 1-20 kGy range with promising results for applications in gamma-ray dosimetry. Results obtained in gamma irradiated MWG are compared with those obtained in graphite powder samples (GP) without microwave treatment. Copyright © 2018 Elsevier Ltd. All rights reserved.

RF Characteristics of Mica-Z Wireless Sensor Network Motes

National Research Council Canada - National Science Library

Koh, Swee J

2006-01-01

... network characteristics. Link-break and re-association distances with their corresponding RF power measurements were recorded to determine the Mica-Z s range characteristics under these different operating environments...

Deserción universitaria y alfabetización académica

OpenAIRE

Giohanny Olave-Arias; llene Rojas-García; Mireya Cisneros-Estupiñán

2013-01-01

El artículo pone en relación la deserción universitaria con la alfabetización académica, entendida como el nivel de desarrollo de la lectura y la escritura. El desarrollo del artículo consta de tres momentos: contextualización del problema de la deserción universitaria en Colombia; prácticas de lectura y escritura que generan dificultades de aprendizaje; importancia de la alfabetización académica para mejorar las habilidades lectoras de los estudiantes.

Topographic characterization of the self-assembled nanostructures of chitosan on mica surface by atomic force microscopy

International Nuclear Information System (INIS)

Wang, Li; Wu, Jiafeng; Guo, Yan; Gong, Coucong; Song, Yonghai

2015-01-01

Graphical abstract: - Highlights: • Nanocomposites of chitosan film were prepared by simple self-assembly from solvent media. • Chitosan molecules assembled on mica surface of nanoparticles, fibril and membrane with varied chitosan concentration. • Chitosan molecules assembled with different nanostructure under varied pH. • The optimum drying temperature for forming chitosan membrane is about 65 °C. - Abstract: In this work, the self-assembled nanostructures of chitosan on mica surface formed from various solvents were investigated by using atomic force microscopy. The effects of various factors on the self-assembled nanostructures of chitosan on mica surface, including solvents, the concentration of chitosan, the pH of solution and the drying temperature, were explored in detail. Our experimental data resulted in the conclusion that chitosan molecules could self-assemble on mica surface to form various nanostructures such as nanoparticles, fibril and film. Nanoparticles were always formed on mica surface from CCl_4, C_6H_6, CH_2Cl_2 solution, fibril preferred to form on mica surface from CH_3CH_2OH and CH_3OH solution and the optimal solvent to form film was found to be CH_3CN. Low concentration, pH and temperature were helpful for the formation of nanoparticles, medium concentration, pH and temperature resulted in fibril and high concentration, pH and temperature were often beneficial to forming chitosan films. The study of self-assembled nanostructures of chitosan on mica surface would provide new insight into the development of chitosan-based load-bearing materials.

Algunas características económicas del mantenimiento no correctivo del software a medida.

OpenAIRE

Torralba Martínez, José María; Rodenes Adam, Manuel

2001-01-01

Se presentan algunas características económicas del servicio de mantenimiento del software, relativas pricipalmente al área comercial: mercado, producto, precio y clientización, apuntando la importancia económica que tiene tanto para

Some mica-vermiculite alterations-relation to the exchange capacity

International Nuclear Information System (INIS)

Misak, N.Z.; Abdel-Gawad, A.S.; Maghrawy, H.B.; Shafik, A.; Sayyah, T.

1983-01-01

The effect of treatment of six Indian mica-vermiculite minerals with sodium cobaltinitrite (I) and NaCl+H 2 O 2 (II) with the aim of producing more vermiculite in the structure and thus a higher sorption capacity, was studied. The changes occuring in the minerals were followed by X-ray, TG, DTA, and chemical analyses. The measured Sr 2+ and Co 2+ capacities were in basic agreement with the detected changes that revealed generally a minor alteration due to treatment I and a considerable one but to treatment II. Treatment II increased tremendously the capacity of the main-mica minerals, having a very small capacity in the natural form, and made them suitable for use as potential ion exchangers

Diagnóstico y tendencias económicas del Corredor Tijuana-Rosarito-Ensenada

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Wilfrido Ruiz Ochoa

2015-01-01

Full Text Available En este artículo se proponen estrategias que pudieran implementarse para romper con un escenario económico inercial adverso que, hipotéticamente, pudiera restarle viabilidad económica a futuro al Corredor Costero Tijuana- Rosarito-Ensenada. Esto, a partir de un diagnóstico económico sustentado en índices multidimensionales, en el que se aporta información censal sobre el perfil sectorial y espacial del corredor, así como de sus tendencias de crecimiento para 2030. Sobre esta base se elaboran propuestas para afrontar la desaceleración económica reciente de la zona, mediante la identificación de sus vocaciones económicas y de algunos proyectos estratégicos.

El derecho de propiedad privada y libertad económica

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Santiago M. Castro Videla

2014-03-01

Full Text Available Este artículo ofrece diversos elementos legales, filosóficos y económicos para una teoría general del derecho de propiedad y libertad económica, que permita explicar por qué es un derecho fundamental. En primer lugar, plantea una visión unificada del derecho de propiedad privada y libertad económica, el que debe distinguirse analíticamente de los distintos derechos de propiedad susceptibles de reglamentación y expropiación estatal. En segundo lugar, explica, desde la teoría tomista del derecho natural, en qué sentido este derecho es un derecho natural secundario. En tercer lugar, señala, desde la teoría austríaca del proceso de mercado, cómo la protección del derecho de propiedad privada y libertad económica da lugar a un proceso virtuoso que genera mayor desarrollo, reducción de la pobreza y paz social. Y finalmente, explica también cómo la violación de dicho derecho genera los efectos contrarios: subdesarrollo, pobreza y conflicto social.

A pura química : Curso a distancia para alumnos e Ingeniería

OpenAIRE

Tocci, Ana María; Fertitta, A. E.; Visintin, Arnaldo

2015-01-01

La Facultad de Ingeniería de la ciudad de La Plata (UNLP) requiere para permitir el ingreso a la misma aprobar un examen de matemáticas, el cual se rinde en el mes de diciembre, o aprobar un curso nivelatorio de la misma materia durante el mes de febrero. En ese curso no está contemplada la materia Química. Los docentes de la cátedra de Química General (materia del primer cuatrimestre de primer año) para Ingeniería Química y Materiales, encontramos un vacío en lo que respecta a conocimientos ...

Deserción universitaria y alfabetización académica

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Giohanny Olave-Arias

2013-12-01

Full Text Available El artículo pone en relación la deserción universitaria con la alfabetización académica, entendida como el nivel de desarrollo de la lectura y la escritura. El desarrollo del artículo consta de tres momentos: contextualización del problema de la deserción universitaria en Colombia; prácticas de lectura y escritura que generan dificultades de aprendizaje; importancia de la alfabetización académica para mejorar las habilidades lectoras de los estudiantes.

Mutaciones dinámicas

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Cesar A. Parra

1994-10-01

Full Text Available EI descubrimiento de repeticiones amplificadas de trinucleótidos variables en número, en pacientes con distrofia miotónica, síndrome de X-frágil, corea de Huntington y enfermedad de Kennedy, al igual que alteraciones en dinucleótidos del DNA microsatélite en pacientes con carcinoma proximal de colon, ha dado origen al concepto de mutaciones dinámicas. Esto representa una nueva avenida en teoría genética contemporánea que explica fenómenos como lo anticipación y la paradoja de Sherman que se salen del patrón mendeliano clásico.

Estrategias sociales y económicas de los nuevos jubilados.

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Antonio Trinidad Requena

2006-01-01

Full Text Available Desde mediados de la década de los ochenta, las personas mayores han ido adquiriendo una especial relevancia y un mayor protagonismo en las sociedades modernas. El jubilado de hoy no es el jubilado del pasado, siendo necesario distinguir entre el jubilado tradicional y el nuevo jubilado, que será el jubilado del futuro. Este nuevo jubilado es el objetivo de este trabajo, centrado en conocer las estrategias sociales y económicas que utilizan para adaptarse a la nueva situación. Para conocer las estrategias sociales y económicas del nuevo jubilado nos centramos en el análisis de sus discursos.

A real-time Raman spectroscopy study of the dynamics of laser-thinning of MoS2 flakes to monolayers

Science.gov (United States)

Gu, Enyao; Wang, Qiyuan; Zhang, Youwei; Cong, Chunxiao; Hu, Laigui; Tian, Pengfei; Liu, Ran; Zhang, Shi-Li; Qiu, Zhi-Jun

2017-12-01

Transition metal dichalcogenides (TMDCs) in monolayer form have attracted a great deal of attention for electronic and optical applications. Compared to mechanical exfoliation and chemical synthesis, laser thinning is a novel and unique "on-demand" approach to fabricate monolayers or pattern desired shapes with high controllability and reproducibility. Its successful demonstration motivates a further exploration of the dynamic behaviour of this local thinning process. Here, we present an in-situ study of void formation by laser irradiation with the assistance of temporal Raman evolution. In the analysis of time-dependent Raman intensity, an empirical formula relating void size to laser power and exposure time is established. Void in thinner MoS2 flakes grows faster than in thicker ones as a result of reduced sublimation temperature in the two-dimensional (2D) materials. Our study provides useful insights into the laser-thinning dynamics of 2D TMDCs and guidelines for an effective control over the void formation.

Nucleation and crystallization behaviors of nano-crystalline lithium–mica glass–ceramic prepared via sol–gel method

Energy Technology Data Exchange (ETDEWEB)

Tohidifar, M.R. [Department of Materials Science and Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Alizadeh, P., E-mail: p-alizadeh@modares.ac.ir [Department of Materials Science and Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Riello, P. [Department of Molecular Sciences and Nanosystems, University of Ca’Foscari, Venice (Italy)

2012-06-15

Graphical abstract: The effects of nucleation and crystallization treatments on nano-crystalline lithium–mica glass–ceramic, synthesized by sol–gel technique, were investigated. It was found that MgF{sub 2} crystals act as nuclei centers for the mica crystallization so that a large quantity of mica crystallites was obtained following nucleation process. The crystallization activation energy for both the un-nucleated and nucleated samples was measured as 400.2 and 229.6 kJ mol{sup −1}, respectively. The calculated Avrami exponents demonstrated that the growth mechanism of mica crystallites changes from the needle-like to three-dimensional growth with applying the appropriate nucleation treatment ▪. Highlights: ► Crystallization temperature shifts to 625 from 680 °C following nucleation process. ► Activation energy of crystallization for the nucleated specimen is 229.6 kJ mol{sup −1}. ► Crystallization activation energy for the un-nucleated specimen is 400.2 kJ mol{sup −1}. ► Needle-like growth is predominant growth mechanism for un-nucleated sample. ► Three-dimensional growth is predominant growth mechanism for nucleated sample. -- Abstract: The paper investigates the effects of nucleation and crystallization treatments on nano-crystalline lithium–mica glass–ceramics, taking the composition LiMg{sub 3}AlSi{sub 3(1+x)}O{sub 10+6x}F{sub 2} (x = 0.5) and 8 mass% MgF{sub 2} synthesized by sol–gel technique. Here, X-ray diffraction, thermal analysis and transmission electron microscopy were used to assess the structural evolutions of as-synthesized nano-crystalline lithium–mica glass–ceramics. It was found that MgF{sub 2} crystals perform as nuclei centers for the mica crystallization hence; a large quantity of mica crystallites obtained following the nucleation process at 400 °C for 12 h. For both the un-nucleated and nucleated samples, the crystallization activation energy was measured as 400.2 and 229.6 kJ mol{sup −1

Fabrication of TiO_2 nanorod assembly grafted rGO (rGO@TiO_2-NR) hybridized flake-like photocatalyst

International Nuclear Information System (INIS)

Lv, Kangle; Fang, Shun; Si, Lingling; Xia, Yang; Ho, Wingkei; Li, Mei

2017-01-01

Highlights: • TiO_2 nanorod assembly grafted with GO hybrid was successfully fabricated. • TiO_2 nanorods can reduce the aggregation of TiO_2 nanoparticles on graphene. • This unique structure facilitates the injection of electron from TiO_2 to graphene. - Abstract: To efficiently separate the photo-generated electron–hole pairs of TiO_2 hybrid, anatase TiO_2 nanorod assembly grafted reduced graphene oxides (rGO@TiO_2-NR) hybrid was successfully fabricated using potassium titanium oxalate (PTO) and graphene oxides (GO) as starting materials and diethylene glycol (DEG) as reductant. The effect of GO content on the structure and photocatalytic activity of rGO@TiO_2-NR composite was systematically studied. Results show that, in the absence of GO, only TiO_2 microsphere assembly is obtained from TiO_2 nanorods. The presence of GO results in the formation of a flake-like TiO_2-nanorod-assembled grafted rGO hybrid. The photocatalytic activity of rGO@TiO_2-NR composite increases first and then decreases with increase in the amount of GO from 0 wt.% to 10 wt.%. The hybridized S4 sample prepared with 4 wt.% GO possesses the highest photocatalytic activity with a constant rate of 0.039 min"−"1 in the photocataytic degradation of Brilliant X-3B dye (X3B); this sample was enhanced more than three times when compared with pure TiO_2 sample (0.012 min"−"1). The enhanced photocatalytic activity of the rGO@TiO_2-NR hybrid was attributed to the strong interaction between TiO_2 nanorods and rGO. The unique hierarchical structure of 1D nanorod assembly TiO_2–rGO flakes facilitates the injection and transfer of photo-generated electrons from TiO_2 to graphene, thus retarding the recombination of electron–hole pairs and enhancing the photocatalytic activity. The enlarged BET surface areas, not only increasing the number of active sites, but also facilitating the adsorption of the dye, and improved light-harvesting ability also contribute to the enhanced photoreactivity

Angeitis necrotizante sistémica no supurativa

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Gabriel Toro G.

1972-04-01

Full Text Available 1. Se estudian 3 casos de angeítis necrotizante sistémica no supurativa: un hombre de 36 y una mujer de 58 años con granulomatosis de Wegener y un hombre de 30 años con granulomatosis alérgica del tipo descrito por Churg y Strauss. 2. Se prefiere el hombre de angeítis necrotizante sistémica no supurativa como lo ha hecho Paronetto cuando trata este capítulo desde el punto de vista inmunopatológico. 3. Consideran los autores que la lesión renal es la periglomerulitis granulomatosa parahiliar y que su presencia ya en la biopsia tiene gran valor diagnóstico. 4. Se subraya que el cuadro clínico, la marcada eosinofilia tisular y la presencia de imágenes micromultinodulares en el ganglio linfático, apoyan sólidamente un diagnóstico de granulomatosis alérgica de la forma descrita por Churg y Strauss. 5. Se hace una amplia revisión bibliográfica.

Habilidades académicas en estudiantes de nuevo ingreso a la Universidad del Zulia

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Mariana Fernández Reina

2015-01-01

Full Text Available Al inicio de su carrera universitaria algunos jóvenes demuestran no poseer las habilidades académicas necesarias para alcanzar la culminación de sus estudios. Esta investigación se enfoca en diagnosticar las habilidades académicas de los estudiantes cuando ingresan a la universidad. Se plantea una investigación descriptiva, con un diseño transeccional, univariable, de campo, no experimental. La población de estudio estuvo conformada por 940 estudiantes que ingresaron al Núcleo Costa Oriental del Lago de la Universidad del Zulia en las carreras de Ingeniería, Ciencias Económicas y Sociales, y Educación, para el primer período de 2012. La muestra seleccionada fue no probabilística, conformada por 179 estudiantes. El instrumento empleado para la recolección de datos fue la escala de habilidades académicas en estudiantes universitarios, compuesta por 40 reactivos, tipo Likert, la cual alcanzó una confiabilidad alfa de Cronbach de 0,86. Según los resultados los estudiantes de nuevo ingreso poseen un nivel bajo de habilidades académicas (organización; empleo de técnicas; motivación, lo cual no les permite abordar con éxito los retos de la vida universitaria. Se sugiere reforzar las mismas a través de la práctica.

Visualisation Ability of Senior High School Students with Using GeoGebra and Transparent Mica

International Nuclear Information System (INIS)

Thohirudin, M; Maryati, TK; Dwirahayu, G

2017-01-01

Visualisation ability is an ability to process, inform, and transform object which suitable for geometry topic in math. This research aims to describe the influence of using software GeoGebra and transparent mica for student’s visualisation ability. GeoGebra is shortness of geometry and algebra. GeoGebra is an open source program that is created for math. Transparent mica is a tool that is created by the author to transform a geometry object. This research is a quantitative experiment model. The subject of this research were students in grade XII of science program in Annajah Senior High School Rumpin with two classes which one as an experiment class (science one) and another one as a control class (science two). Experiment class use GeoGebra and transparent mica in the study, and control class use powerpoint in the study. Data of student’s visualisation ability is collected from posttest with visual questions which are gifted at the end of the research to both classes with topic “transformation geometry”. This research resulted that studying with GeoGebra and transparent mica had a better influence than studying with powerpoint to student’s visualisation ability. The time of study in class and the habit of the students to use software and tool affected the result of research. Although, GeoGebra and transparent mica can give help to students in transformation geometry topic. (paper)

La caja negra de la dinámica empresarial

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María Callejón

2009-01-01

Full Text Available Este artículo intenta aportar conocimientos sobre la contribución a la política industrial de la investigación en dinámica empresarial. Los programas de fomento a la creación de empresas se han generalizado aunque se desconoce cuál es el ritmo óptimo de creación y destrucción empresarial. El análisis económico destaca la heterogeneidad empresarial como característica dominante en la dinámica industrial. La profundización en el conocimiento de los tipos de emprendedores, su comportamiento, y su contribución diferencial a la innovación y el crecimiento permitirá ver en la "caja negra" y diseñar programas públicos adecuados. El análisis empírico realizado encuentra que la naturaleza económica del autoempleo es muy diferente de las empresas con empleados. Los programas públicos deberían priorizar entrantes con capacidad de sobrevivir y no maximizar la entrada indiscriminadamente. La supervivencia de las nuevas empresas se encuentra positivamente relacionada con su tamaño al nacer. La innovación y la inversión mejoran la supervivencia de las nuevas empresas manufactureras. La inversión en I+D aumenta el riesgo de las nuevas empresas, aunque mejore la competitividad de las empresas establecidas.

La caja negra de la dinámica empresarial

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María Callejón

2009-10-01

Full Text Available Este artículo intenta aportar conocimientos sobre la contribución a la política industrial de la investigación en dinámica empresarial. Los programas de fomento a la creación de empresas se han generalizado aunque se desconoce cuál es el ritmo óptimo de creación y destrucción empresarial. El análisis económico destaca la heterogeneidad empresarial como característica dominante en la dinámica industrial. La profundización en el conocimiento de los tipos de emprendedores, su comportamiento, y su contribución diferencial a la innovación y el crecimiento permitirá ver en la “caja negra” y diseñar programas públicos adecuados. El análisis empírico realizado encuentra que la naturaleza económica del autoempleo es muy diferente de las empresas con empleados. Los programas públicos deberían priorizar entrantes con capacidad de sobrevivir y no maximizar la entrada indiscriminadamente. La supervivencia de las nuevas empresas se encuentra positivamente relacionada con su tamaño al nacer. La innovación y la inversión mejoran la supervivencia de las nuevas empresas manufactureras. La inversión en I+D aumenta el riesgo de las nuevas empresas, aunque mejore la competitividad de las empresas establecidas.

MICA: desktop software for comprehensive searching of DNA databases

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Glick Benjamin S

2006-10-01

Full Text Available Abstract Background Molecular biologists work with DNA databases that often include entire genomes. A common requirement is to search a DNA database to find exact matches for a nondegenerate or partially degenerate query. The software programs available for such purposes are normally designed to run on remote servers, but an appealing alternative is to work with DNA databases stored on local computers. We describe a desktop software program termed MICA (K-Mer Indexing with Compact Arrays that allows large DNA databases to be searched efficiently using very little memory. Results MICA rapidly indexes a DNA database. On a Macintosh G5 computer, the complete human genome could be indexed in about 5 minutes. The indexing algorithm recognizes all 15 characters of the DNA alphabet and fully captures the information in any DNA sequence, yet for a typical sequence of length L, the index occupies only about 2L bytes. The index can be searched to return a complete list of exact matches for a nondegenerate or partially degenerate query of any length. A typical search of a long DNA sequence involves reading only a small fraction of the index into memory. As a result, searches are fast even when the available RAM is limited. Conclusion MICA is suitable as a search engine for desktop DNA analysis software.

Compatibilidad entre nueve cepas de Biomphalaria glabrata de áreas endémicas y no endémicas y una cepa de Schistosoma mansoni venezolanas

OpenAIRE

Pino,Luz A.; Matinella,Liboria; Morales C.,Gustavo

1999-01-01

Se infectaron experimentalmente 9 lotes de 32 caracoles B. glabrata (de 5 a 7mm de diámetro) con miracidios de la cepa C5 de Schistosoma mansoni a razón de 5 miracidios por caracol, pertenecientes a las siguientes cepas: En el área endémica de transmisión de Esquistosomiasis mansoni a) Sector Puerta Negra, Lago Valencia, b) Cagua c) Ingenio Bolívar (Estado Aragua) d) Mariara e) Caserío El 25 f) Güigüe (Estado Carabobo). Fuera del área endémica de transmisión g) Anzoátegui (Estado Lara), h) Ch...

Mejora en la motivación por la Lectura Académica: la mirada de estudiantes motivados

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Carla Muñoz

2016-01-01

Full Text Available Dada la importancia de la lectura académica en la formación universitaria y que uno de los factores gravitantes en este tipo de tarea son los aspectos motivacionales, el presente trabajo tuvo como objetivo identificar los elementos, que según los propios protagonistas explicarían el incremento de su motivación por la lectura de textos académicos. El estudio de carácter mixto se realizó en dos fases. En una primera fase fueron identificados a partir de una muestra amplia (n=1205 estudiantes con alta motivación por la lectura académica y que hubiesen experimentado un cambio motivacional positivo (n=10. En una segunda fase, estos casos fueron sujetos de entrevistas en profundidad y el análisis de estas entrevistas se recogen en este artículo. Los resultados muestran como causas de la mejora de la motivación por la lectura académica, dinámicas vinculadas con el desafío, el ingreso a la lógica universitaria (desescolarización y las proyecciones académico/profesionales de estos estudiantes; procesos que se encuentran vinculados a los primeros años de formación, favorecidos por docentes que promueven una dinámica académica en la formación. Se discuten finalmente las implicaciones de estas dinámicas para la formación universitaria.

Electrohidrodinámica de cristales líquidos nemáticos

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Rosalío F. Rodríguez

2001-01-01

Full Text Available Se presenta un formalismo analítico que permite describir una amplia variedad de fenómenos ópticos no lineales que ocurren cuando una onda electromagnética se propaga en un cristal líquido. A partir de propiedades termodinámicas y de simetría, primero se construye un conjunto cerrado de ecuaciones hidrodinámicas que proporcionan una descripción completa de la dinámica de un nemático de bajo peso molecular en ausencia de campos externos. Posteriormente, se incluye la presencia de un campo electromagnético externo que se propaga en el fluido. Se discute el carácter no lineal y acoplado de las ecuaciones y, para resolverlas, se propone un método iterativo de aproximaciones sistemáticas en términos de potencias de parámetros con una interpretación física precisa. Se concluye discutiendo las ventajas y limitaciones del punto de vista adoptado en este trabajo..

A dinâmica do crédito no Brasil entre 1990-2006.

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Juliano Morais Galle

2008-05-01

Full Text Available Este artigo aborda, dentro de um contexto de globalização financeira, a dinâmica e o desenvolvimento recente do mercado financeiro e de crédito no Brasil. É mostrado que a dinâmica do crédito se caracterizou por três fases distintas entre 1990 e 2003. Além disso, discute-se que, após a implantação do Plano Real, houve um grande esforço por parte do governo brasileiro em reestruturar e reforçar o Sistema Financeiro Nacional, e que a conjuntura econômica observada atualmente no Brasil é bem mais favorável ao crescimento da relação crédito/PIB que no início da década de 2000.

CARACTERIZACIÓN MORFOLÓGICA Y ANATÓMICA DEL GÉNERO STEREOCAULON HOFFMANN (ASCOMYCETES-LIQUENIZADOS EN COLOMBIA

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ANGÉLICA RINCÓN-ESPITIA

2013-12-01

Full Text Available El género Stereocaulon presenta una gran plasticidad en sus estructuras morfológicas y anatómicas, que de no ser reconocidas se puede recaer en errores taxonómicos a nivel intraespecífico. Por esta razón, se presenta una diferenciación morfoanatómica de los caracteres diagnósticos: los filocladios, los cefalodios y los soredios para facilitar el proceso de identificación taxonómica. En esta contribución se reconocen 19 especies junto con cinco variedades de Stereocaulon para Colombia, se amplían los datos de distribución geográfica y se incluye una clave taxonómica para la identificación de las especies en el país.

Sobre lo económico de la Historia Económica: Dos concepciones contrapuestas

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Nicolás Mohaded

2013-05-01

Full Text Available Las tendencias a incrementar las contribuciones interdisciplinarias no son ajenas a la ciencia económica. Desde distintas vertientes teóricas gran cantidad de autores han intentado lograr explicaciones más comprehensivas sobre la realidad social a partir de la confluencia de disciplinas. El caso de la historia económica como conjunción de la economía y la historia puede dar cuenta de ello. Sin embargo, no existe una única manera de enfocar el análisis en esta dirección. En este sentido, este trabajo presenta dos corrientes teóricas distintas en relación a la historia económica. Por un lado el enfoque neo-institucionalista de North y Thomas y por otro el enfoque marxista de Dobb. Se plantean las distintas perspectivas teóricas que cada uno de estos dos aparatos analíticos proponen, particular-mente en lo referido a lo económico de la historia económica, y sus implicancias sobre el análisis de la realidad social.

Planificación de trayectorias para un robot tipo con restricciones dinámicas

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Leonardo Solaque Guzmán

2008-01-01

Full Text Available Este documento presenta una aproximación a la planificación de caminos óptimos para un sistema con restricciones dinámicas y desplazándose dentro de un espacio libre de obstáculos. Se considera el modelo dinámico del dirigible y un análisis para el planteamiento de modelos simplificados o comúnmente conocidos como modelos de control. Se propone una planificación de la trayectoria desde el punto de vista de la teoría óptima utilizando un modelo de la dinámica de un robot móvil (que se desplaza a velocidad constante y en avance, es decir con restricciones dinámicas como punto de partida para la primera aproximación a los caminos óptimos. Para el suavizado de las trayectorias del dirigible se proponen dos modelos con relajación en la dinámica de la variable de control y finalmente se presenta una simulación de la comparación de los diferentes resultados.

DINÂMICA ECONÔMICA E REDE URBANA CEARENSE NO INÍCIO DO SÉCULO XXI

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Fernando Cezar de Macedo

2012-03-01

Full Text Available Este artigo discute a dinâmica econômica e a evolução da rede urbana do Ceará nesta primeira década do século XXI. Além das heranças seculares, toma como elemento decisivo na estruturação do espaço cearense as diversas políticas implementadas pelos governos estaduais que articularam a economia cearense aos movimentos das economias brasileira e internacional, influenciando sua organização espacial. Mostra que foi no período colonial que a capital cearense tornou-se principal centro urbano do estado graças à centralização dos excedentes das atividades sertanejas sustentadas no binômio pecuária-algodão. Posteriormente, apresenta as transformações verificadas na fase de integração do mercado nacional, quando se concentraram os principais investimentos na cidade de Fortaleza. Dada essa grande concentração, observam-se esforços de descentralização da atividade produtiva, a partir de uma ação deliberada do governo do estado, através dos instrumentos da guerra fiscal que atraíram para o interior importantes investimentos, sem, contudo, reduzir as disparidades intraestaduais ainda fortemente marcadas pelo predomínio metropolitano. Não obstante, surgem focos dinâmicos na economia cearense, contribuindo para uma maior diferenciação do interior do estado.

A crise econômica de 2014/2017

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Fernando de Holanda Barbosa Filho

Full Text Available Resumo Este artigo mostra que a crise de 2014/2017 é fruto de uma combinação de choques de oferta e demanda resultado de erros de política econômica. Esses choques produziram uma redução da capacidade de crescimento da economia brasileira e risco de insolvência das finanças públicas. A solução da crise fiscal, através da PEC do teto dos gastos, fará que o país retome o crescimento econômico a partir de 2017, utilizando a capacidade ociosa da economia. No entanto, a taxa de crescimento do produto potencial não recuperará o ritmo anterior devido aos efeitos duradouros das políticas da Nova Matriz Econômica (NME que reduziram o produto potencial nacional. Recomenda-se, portanto, a adoção de políticas que induzam uma recuperação da produtividade da economia brasileira.

Introducción a la Química Orgánica

OpenAIRE

Autino, Juan Carlos; Romanelli, Gustavo Pablo; Ruiz, Diego Manuel

2013-01-01

Esta obra ha sido concebida atendiendo a las características del Curso de Química Orgánica que ofrecemos en la Facultad de Ciencias Agrarias y Forestales de la Universidad Nacional de La Plata a nuestros alumnos del primer año de las Carreras de Ingeniería Agronómica e Ingeniería Forestal, así como del segundo año de la Licenciatura en Biología. En la misma incorporamos elementos didácticos que hemos introducido y mejorado gradualmente durante varios años, logrando un cierto grado de original...

Avaliação física, química e fitoquímica de frutos de Physalis, ao longo do período de colheita

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Cláudia Simone Madruga Lima

2012-12-01

Full Text Available Physalis peruviana L. é uma espécie que vem sendo incorporada em plantios de pequenas frutas. Esta frutífera é tratada como anual, e o principal método de propagação é por sementes. Seu cultivo apresenta uma dinâmica de colheita diferenciada, com duração do período de colheita superior a três meses. Acredita-se que, devido ao extenso período de colheita, associado a diferentes épocas de semeadura, irão ocorrer variações nas características dos frutos. O objetivo deste trabalho foi avaliar as características físicas, químicas e fitoquímicas de frutos de Physalis peruviana ao longo do período de colheita, em função de duas épocas de plantio. O experimento foi realizado no período de 2007/2008. A semeadura foi realizada em duas épocas (04-09-2007 e 26-11-2007, e o transplante foi realizado quando as plantas estavam no estádio de duas folhas verdadeiras. Os frutos foram colhidos aos 120; 150; 180; 210 e 240 dias após o transplante e avaliados quanto à massa total e a coloração da epiderme, assim como quanto aos seus teores de sólidos solúveis (SS, acidez titulável (AT, fenóis e de carotenoides totais, razão SS/AT e atividade antioxidante. Os frutos de Physalis apresentaram variações físicas, químicas e fitoquímicas ao longo do período de colheita, para as duas datas de semeadura. O desenvolvimento das plantas, após o transplantio, levou a acréscimo nos valores de massa, nos teores de sólidos solúveis, fenóis e carotenoides, assim como na razão SS/AT. Na coloração e na atividade antioxidante, os maiores valores foram obtidos na primeira colheita (120 dias. A semeadura realizada em setembro proporcionou a obtenção de frutos com melhor qualidade.

Evaluation of gamma and neutron irradiation effects on the properties of mica film capacitors

International Nuclear Information System (INIS)

Roy, Rajesh; Pandya, Arun

2005-01-01

We present an investigation of gamma and neutron radiation effects on mica film capacitors from an electrical point of view. We have studied quantitatively the effects of gamma and neutron irradiation on mica film capacitors of thickness, 20 and 40 μm (0.7874 and 1.5748 mil) with two different areas, 01 and 04 cm 2 . The capacitance has been measured at room temperature in the frequency range 100 Hz-10 MHz. Negligible change in the capacitance due to high gamma dose of 60 Co, 15 kGy at dose rate 0.25 kGy/h, has been observed. However, appreciable change in the capacitance has been observed due to low doses of fast neutrons (cumulative dose, 115 cGy) with flux ∼ 9.925 X 10 7 neutrons/cm 2 h from 252 Cf neutron source of fluence, 2.5 x 10 7 neutrons/s. We have also observed that the impact of gamma and neutron irradiation is more at frequencies higher than 10 kHz, These results show that the mica capacitors do not show any radiation response below 10 kHz. The study shows the radiation response of mica film capacitors to gamma and fast neutron radiations. Mica capacitors show low gamma radiation response in comparison to fast neutron radiation, because a total dose of kGy order has been given by gamma source and only few cGy dose has been given by fast neutron source. (author)

Complement-fixing antibodies against denatured HLA and MICA antigens are associated with antibody mediated rejection.

Science.gov (United States)

Cai, Junchao; Terasaki, Paul I; Zhu, Dong; Lachmann, Nils; Schönemann, Constanze; Everly, Matthew J; Qing, Xin

2016-02-01

We have found antibodies against denatured HLA class I antigens in the serum of allograft recipients which were not significantly associated with graft failure. It is unknown whether transplant recipients also have denatured HLA class II and MICA antibodies. The effects of denatured HLA class I, class II, and MICA antibodies on long-term graft outcome were further investigated based on their ability to fix complement c1q. In this 4-year retrospective cohort study, post-transplant sera from 975 kidney transplant recipients were tested for antibodies against denatured HLA/MICA antigens and these antibodies were further classified based on their ability to fix c1q. Thirty percent of patients had antibodies against denatured HLA class I, II, or MICA antigens. Among them, 8.5% and 21.5% of all patients had c1q-fixing and non c1q-fixing antibodies respectively. There was no significant difference on graft survival between patients with or without antibodies against denatured HLA/MICA. However, when these antibodies were further classified according to their ability to fix c1q, patients with c1q-fixing antibodies had a significantly lower graft survival rate than patients without antibodies or patients with non c1q-fixing antibodies (p=0.008). In 169 patients who lost renal grafts, 44% of them had c1q-fixing antibodies against denatured HLA/MICA antigens, which was significantly higher than that in patients with functioning renal transplants (25%, pantibodies were more significantly associated with graft failure caused by AMR (72.73%) or mixed AMR/CMR (61.9%) as compared to failure due to CMR (35.3%) or other causes (39.2%) (p=0.026). Transplant recipients had antibodies against denatured HLA class I, II, and MICA antigens. However, only c1q-fixing antibodies were associated with graft failure which was related to antibody mediated rejection. Copyright © 2015 Elsevier Inc. All rights reserved.

Vida académica de la facultad

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Facultad de Medicina Revista

1999-01-01

Enciclopedia Académica sobre el Lenguaje en las Ciencias de la Salud / Convenio con la Universidad de Alcalá de Henares / Libro de Biología / XI Congreso de actualización en Rehabilitación Médica. Dolor crónico, diagnóstico y manejo integral / Primer Congreso Latinoamericano de Estudiantes de Nutrición y Dietética

La imagen y el cine en la enseñanza de la historia económica

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Joan Miguel Tejedor Estupiñán

2018-01-01

Full Text Available Este artículo presenta el modelo de enseñanza desarrollado en las asignaturas de Historia Económica de Colombia e Historia Económica Mundial, en el programa de Economía de la Universidad Católica de Colombia, 2014 y 2015, cuyo objetivo es abordar los problemas históricos de la economía, a través de las fuentes tradicionales, complementadas con la fotografía, el cine, y demás herramientas que brindan las nuevas tecnologías de la comunicación. En la primera parte se describe el contexto de la educación en Colombia en lo que se refiere a la catedra de Historia Económica, en la segunda parte, se describe el modelo de enseñanza de la historia económica a través del cine, en la tercera parte se presenta un listado de films para complementar el proceso de enseñanza de la historia económica, en la cuarta parte se enumeran algunos recursos didácticos y fuentes de investigación que ofrece la internet, y finalmente se presentan las conclusiones.

Uso de rejeitos de granitos como matérias-primas cerâmicas

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Menezes R. R.

2002-01-01

Full Text Available A indústria do beneficiamento de granito gera uma enorme quantidade de rejeitos, que poluem e degradam o meio ambiente. Assim este trabalho tem por objetivo caracterizar e avaliar as possibilidades de utilização dos rejeitos da serragem de granitos gerados pelas indústrias de beneficiamento da Região Nordeste, como matéria-prima cerâmica alternativa na produção de blocos e revestimentos cerâmicos. Foram coletadas amostras de resíduos da serragem de granito em empresas da Paraíba, Ceará e Pernambuco, em seguida foi realizada sua caracterização através da determinação da distribuição granulométrica, massa específica real e área específica (BET e de análise química, ATD, ATG, DRX, MEV. Após caracterização foram conduzidos ensaios tecnológicos com composições cerâmicas a fim de avaliar a possibilidade de adição dos resíduos em massas cerâmicas para confecção de blocos e revestimentos cerâmicos. Com base nos resultados verificou-se que os resíduos apresentam características físicas e mineralógicas semelhantes as das matérias-primas cerâmicas convencionais e que corpos cerâmicos formulados com resíduos apresentam características dentro das especificações da normalização brasileira tanto para blocos como para revestimentos cerâmicos.

Inmigrantes sirio-libaneses y sus prácticas económicas (ilegales en Colombia, 1880-1930

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Ana Milena Rhenals Doria

2018-01-01

Full Text Available Entre 1880 y 1930, Colombia recibió un número significativo de inmigrantes procedentes de Siria y Líbano, quienes, a través de distintas actividades empresariales, terminaron siendo parte de la élite económica de varias ciudades colombianas. En este artículo estudio ese proceso de consolidación económica, haciendo énfasis en las prácticas económicas ilegales en las que incurrieron algunos de los inmigrantes siriolibaneses que se establecieron en el circuito comercial existente entre la provincia del Sinú, Cartagena y el Atrato. Argumento que actividades como la falsificación de monedas, el contrabando y el acaparamiento de tierras intervinieron en el proceso de acumulación de capital y de consolidación económica que algunos de estos inmigrantes lograron.

Adsorption of ion pairs onto graphene flakes and impacts of counterions during the adsorption processes

Science.gov (United States)

Zhu, Chang; Yun, Jiena; Wang, Qian; Yang, Gang

2018-03-01

Although cations and anions are two integral constituents for all electrolytes, adsorption of ion pairs onto carbonaceous materials gains obviously less attention than adsorption of only cations or anions. Here DFT calculations are employed finding that four adsorption configurations emerge for KI onto graphene flakes (GF) instead of three for the other ion pairs. Reservation of ionic bonds is critical to their stabilities, and the bilateral configurations, where GFs couple with both cations and anions, are disfavored due to rupture of ionic bonds. Relative stabilities of two vertical configurations can be regulated and even reversed through edge-functionalization. Surprisingly, the horizontal adsorption configurations, which are global energy minima as long as present, are non-existent for a majority of ion pairs, and their existence or not is determined by the adsorption differences between halide ions and alkali ions (△Ead). Counterions effects for both cations and anions increase with the atomic electronegativities and cations correspond to stronger counterion effects; e.g., Li+ added on the other side of GFs promotes the adsorption of F- more pronouncedly than edge-functionalization. Mechanisms of electron transfers are also discussed, and three alteration patterns by counterions are observed for each type of adsorption configurations. Furthermore, addition of counterions causes band gaps to vary within a wider range that may be useful to design electronic devices.

Cargas aerodinâmicas e pré-projeto estrutural de asa de aeronave de 50 passageiros

OpenAIRE

Lauro Cavalcanti de Sá

2010-01-01

Neste trabalho foi realizado o cálculo das cargas aerodinâmicas e o pré-projeto estrutural de asa de uma aeronave de 50 passageiros durante o Mestrado Profissionalizante em Engenharia Aeronáutica e Mecânica, ministrado pelo ITA em parceria com a EMBRAER, através do seu Programa de Especialização em Engenharia. Primeiramente, o modelo estrutural foi desenvolvido baseando-se nas características aerodinâmicas iniciais da aeronave, possibilitando que o programa de análise aerodinâmica BLWF fosse ...

A Simple Transmission Electron Microscopy Method for Fast Thickness Characterization of Suspended Graphene and Graphite Flakes.

Science.gov (United States)

Rubino, Stefano; Akhtar, Sultan; Leifer, Klaus

2016-02-01

We present a simple, fast method for thickness characterization of suspended graphene/graphite flakes that is based on transmission electron microscopy (TEM). We derive an analytical expression for the intensity of the transmitted electron beam I 0(t), as a function of the specimen thickness t (tgraphite). We show that in thin graphite crystals the transmitted intensity is a linear function of t. Furthermore, high-resolution (HR) TEM simulations are performed to obtain λ for a 001 zone axis orientation, in a two-beam case and in a low symmetry orientation. Subsequently, HR (used to determine t) and bright-field (to measure I 0(0) and I 0(t)) images were acquired to experimentally determine λ. The experimental value measured in low symmetry orientation matches the calculated value (i.e., λ=225±9 nm). The simulations also show that the linear approximation is valid up to a sample thickness of 3-4 nm regardless of the orientation and up to several ten nanometers for a low symmetry orientation. When compared with standard techniques for thickness determination of graphene/graphite, the method we propose has the advantage of being simple and fast, requiring only the acquisition of bright-field images.

Resinas quelantes amidoxímicas Amidoxime chelating resins

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Fernanda M. B. Coutinho

1999-12-01

Full Text Available Resinas quelantes com grupos amidoxima foram sintetizadas por copolimerização em suspensão de acrilonitrila (AN e divinilbenzeno (DVB e subsequente modificação química dos grupos ciano por reação com hidroxilamina. Na copolimerização, a proporção de divinilbenzeno e o grau de diluição foram variados. Gelatina e carbonato de cálcio foram usados como estabilizadores de suspensão e sulfato de sódio foi adicionado para reduzir a solubilidade da acrilonitrila em água, por meio do efeito salting out. Os copolímeros de AN/DVB e as resinas amidoxímicas obtidos foram caracterizados por meio de densidade aparente, área específica, volume de poros e teor de nitrogênio. As resinas amidoxímicas foram também avaliadas em relação a capacidade de complexação de íons cobre.Chelating resins with amidoxime groups were synthesized by suspension copolymerization of acrylonitrile (AN and divinylbenzene (DVB and subsequent chemical modification of cyano groups by reaction with hydroxylamine. In the copolymerization, the proportion of divinylbenzene and the dilution degree were varied. Gelatin and calcium carbonate were used as suspension stabilizers and sodium sulphate was added in order to reduce acrylonitrile solubility in water, by salting out effect. The AN/DVB copolymers and amidoxime resins obtained were characterized by apparent density, surface area, pore volume and by the content of nitrogen. The amidoxime resins were also evaluated in relation to the complexation capacity of copper ion.

Neosporosis epidémica y endémica: descripción de dos eventos en bovinos para cría

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Patricio M Calandra

2014-12-01

Full Text Available El objetivo de este trabajo es describir dos eventos producidos en la provincia de Buenos Aires en los cuales Neospora caninum estuvo asociado a la ocurrencia de abortos en bovinos de cría para carne. En uno de ellos se registraron 11 abortos en 57 vaquillonas durante 45 días, en este evento fue 5 veces más probable que una vaquillona que sufrió un aborto fuera seropositiva a N. caninum que una que no lo sufrió (odds ratio [OR] = 4,9 IC 1,2-19,9 (p 0,05. Se analizaron dos fetos de cada evento: estos resultaron negativos a otros patógenos de la reproducción, aunque presentaron anticuerpos específicos y lesiones histopatológicas compatibles con infecciones por N. caninum. Estos resultados sugieren dos posibles modalidades de presentación de abortos en bovinos causados por N. caninum: una epidémica, como la del primer evento aquí referido, y una endémica, como la del segundo.

El etanol como materia prima petroquímica

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Luis M. Carballo

1981-07-01

Full Text Available En este trabajo se presentan los aspectos relevantes de un programa a de investigación, aprobado por el CINDEC y COLCIENCIAS, sobre el desarrollo y estudio cinético de catalizadores para algunas reacciones químicas en las que el etanol está involucrado como reactante.

La construcción de identidades docentes como constructo de estructura y dinámica sistémicas: argumentación y virtualidades teóricas y prácticas

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Amélia Lopes

2007-01-01

Full Text Available Resaltando la importancia de que, en los estudios sobre la identidad docente, se invierta en la configuración de una perspectiva teórica integrada y elaborada y teniendo como referente la biografía investigativa de la autora, este artículo tiene como objetivos presentar la “construcción de identidades profesionales docentes” como un constructo de estructura y dinámica sistémicas e indicar sus virtualidades teóricas y prácticas. Tras una exposición inicial sobre las concepciones de identidad enmarcadas por el interaccionismo simbólico y el sentido que en ellas se vislumbra, se desarrolla una argumentación en dos fases: una relativa a la crisis de identidad de los profesores y otra referente a la construcción de nuevas identidades. Se concluye destacando las virtualidades de considerar a la construcción de nuevas identidades docentes como un constructo de estructura y dinámica sistémicas, concretamente: la posibilidad de que se relacione la construcción de identidades profesionales y los procesos de profesionalización docente; y la importancia de que se piense la formación de profesores a los diversos niveles del sistema, teniendo en cuenta sus especificidades e interacciones

La Química, la Ingeniería Química y su relación con otras disciplinas La Química, la Ingeniería Química y su relación con otras disciplinas

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Antonio Valiente Barderas

2012-02-01

Full Text Available Chemical Engineering as such has a little more than a hundred years of existence. During this time, his development has generated research, data and books which made innovations in the curriculum and new paradigms in education. The development of this discipline has influenced the creation or modification of others such as Environmental Engineering, Food Engineering, Electrochemical Engineering, Metallurgical Engineering, etc. The future presents new challenges and opportunities for development in the area of biofuels, nanotechnology and climate control.La Ingeniería Química, como tal, tiene apenas un poco más de cien años de existencia. Durante ese tiempo la enseñanza de la misma ha ido cambiando conforme se generaron investigaciones, datos y libros que produjeron innovaciones en el currículo y nuevos pa­radigmas de la enseñanza. El desarrollo de esta disciplina ha incidido en la creación o modificación de otras más, tal como la Ingeniería Ambiental, la Ingeniería de Alimentos, la Bioingeniería, la Ingeniería Electroquímica y la Ingeniería Metalúrgica, etc. En el futuro se presentan nuevos retos y oportunidades de desarrollo en el área de los biocombustibles, la nanotecnología, los nuevos materiales y el control climático.

EL PROTEOMA DEL TEJIDO ADIPOSO SUBCUTÁNEO MUESTRA HETEROGENEIDAD ANATÓMICA

Science.gov (United States)

Martos-Moreno, G.A.; Sackmann-Sala, L.; Berryman, D.E.; Blome, D.W.; Argente, J.; Kopchick, y J.J.

2015-01-01

Introducción El tejido adiposo blanco (TAB) subcutáneo (Sc) humano podría variar dependiendo de su localización anatómica, con diferencias en su perfil proteómico. Pacientes y métodos Se obtuvieron aspirados de TAB-Sc de seis mujeres con IMC >25 kg/m2, sometidas a liposucción. Dicho TAB-Sc se obtuvo de seis localizaciones anatómicas: abdominal superior e inferior, muslo, dorsal, flanco y cadera, analizándose su perfil proteómico mediante electroforesis bidimensional. En muslo y abdomen superior se compararon, además, las muestras obtenidas de las dos capas del TAB-Sc (profunda y superficial). Resultados Se detectaron 21 proteínas que mostraban una intensidad de expresión diferente entre las seis localizaciones anatómicas y 14 entre las capas superficial y profunda de una misma región. Entre las proteínas identificadas se incluyen: vimentina (proteína estructural); proteínas “heat-shock” (HSPs), superóxido-dismutasa, (estrés/chaperoninas); proteína fijadora de ácidos grasos 4 (FABP-4) y alfa-enolasa (metabolismo lipídico y de los hidratos de carbono, respectivamente) y ATP-sintetasa (producción de energía). Entre las regiones estudiadas, el TAB-Sc dorsal mostraba un perfil proteómico particular, con menor expresión de proteínas implicadas en la producción de energía y metabolismo (ATP-sintetasa, alfa-enolasa, HSPs y FABP-4) que el resto de regiones. Conclusiones Los niveles de expresión de diversas proteínas en el TAB-Sc humano no son homogéneos, difiriendo entre localizaciones anatómicas. Esto sugiere la existencia de diferencias funcionales en el TAB-Sc de acuerdo con su localización anatómica, lo que debe considerarse antes de asumir la extrapolación de los datos derivados del TAB-Sc de una determinada localización al de otras partes de la anatomía. PMID:23228439

Effect of waste mica on transfer factors of 134Cs to spinach and lettuce

International Nuclear Information System (INIS)

Sreenivasa Chari, M.; Manjaiah, K.M.; Sachdev, P.; Sachdev, M.S.

2011-01-01

A greenhouse pot culture experiment was conducted to study the effect of graded levels of waste mica (0, 10, 20 and 40 g kg -1 ) on reducing the radiocesium uptake by spinach (Spinacia olerecea L) and lettuce (Lactuca sativa L.) grown in 134 Cs-contaminated (at 37 k Bq kg -1 soil) Inceptisols, Vertisols and Ultisols. The biomass yield, and potassium content and its uptake by crops have been significantly improved by waste mica application. The crops grown in Vertisols recorded higher biomass yield, and K content and its uptake as compared with Inceptisols and Ultisols. The average 134 Cs transfer factor values recorded were: 0.21, 0.17 and 0.26 at the first cutting, 0.15, 0.12 and 0.28 at the second cutting and 0.07, 0.05 and 0.23 at the third cutting from Inceptisols, Vertisols and Ultisols, respectively. Waste mica significantly suppressed radiocesium uptake, the effect being more pronounced at 40 g mica kg -1 soil. There exists an inverse relationship between the 134 Cs transfer factors with plant potassium content and also the K uptake by the crops. (authors)

Experiments on the incorporation of concentrated solutions of fission products in glasses and micas

International Nuclear Information System (INIS)

Bonniaud, R.; Cohen, P.; Sombret, C.

1958-01-01

1) The plants designed for extracting the plutonium of the G1, G2, G3 reactors fuel rods will produce extremely concentrated solutions of fission products. 2) Let us consider a synthetic solution of the 'G2' type: (2N NO 3 H - 2,25 meq/cm 3 AI +++ - 5.10 -3 134 Cs - 137 Cs tracer). We made various glasses and micas by adding and mixing the necessary adjuvants and baking (900 to 1400 deg. C) in a graphite crucible. 3) The products obtained had either the shape of a cylindrical pellet or were reduced into a fine powder. They were mixed with 300 cm 3 of synthetic sea water during variable periods of time in order to study leaching of the activity. 4) Experiments were first carried on caesium because of its solubility. 5) Fabrication of micas on a large scale sets many technological problems more difficult to solve (1400 deg. C) than in the case of glasses (1000 deg. C). A comparative study on both micas and glasses showed that leaching of activity was more important in the micas. (author) [fr

EL CURRÍCULO UNIVERSITARIO COMO ESCENARIO DE TENSIONES SOCIALES Y ACADÉMICAS

OpenAIRE

Mercedes Collazo

2017-01-01

Los retos que hoy plantean al currículo universitario los nuevos requerimientos de ajuste entre educación superior, empleo y sociedad en el marco de las dinámicas de globalización advierten la necesidad de construir una mirada académica que profundice los alcances y límites de los campos de formación, en razón de sus estructuras de conocimiento implicadas y en el contexto de sus particulares tradiciones profesionales y educativas. En tal sentido, el presente trabajo procura abordar el...

Avaliação econômica de plantações de eucalipto submetidas a desbaste

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Soares Thelma Shirlen

2003-01-01

Full Text Available O objetivo deste estudo foi determinar, através de métodos de avaliação econômica, a idade econômica de corte de plantações de eucalipto submetidas a desbaste. Para tanto, foram utilizados dados de um experimento de desbastes estabelecido na região nordeste da Bahia. Foram consideradas as variações de intensidades de desbaste (0, 20, 40 e 60% de retirada em área basal para projeções realizadas em diferentes classes de local. O método de avaliação econômica utilizado foi o valor anual equivalente. Na análise de sensibilidade foram levadas em conta taxas de desconto de 6, 9 e 12%. Os resultados evidenciaram que a rotação econômica propicia maior lucratividade quando se realiza desbaste.

Effect of protein solution components in the adsorption of Herbaspirillum seropedicae GlnB protein on mica.

Science.gov (United States)

Ferreira, Cecília F G; Benelli, Elaine M; Klein, Jorge J; Schreiner, Wido; Camargo, Paulo C

2009-10-15

The adsorption of proteins and its buffer solution on mica surfaces was investigated by atomic force microscopy (AFM). Different salt concentration of the Herbaspirillum seropedicae GlnB protein (GlnB-Hs) solution deposited on mica was investigated. This protein is a globular, soluble homotrimer (36kDa), member of PII-like proteins family involved in signal transducing in prokaryote. Supramolecular structures were formed when this protein was deposited onto bare mica surface. The topographic AFM images of the GlnB-Hs films showed that at high salt concentration the supramolecular structures are spherical-like, instead of the typical doughnut-like shape for low salt concentration. AFM images of NaCl and Tris from the buffer solution showed structures with the same pattern as those observed for high salt protein solution, misleading the image interpretation. XPS experiments showed that GlnB protein film covers the mica surface without chemical reaction.

¿Oferta o renovación académica?

OpenAIRE

Serani Prádenas, Edmundo

2017-01-01

Aunque sin divulgar una definición, lo que es altamente preocupante, las autoridades universitarias han legitimado el término "Renovación de la Oferta Académica", el que en nuestra opinión tiene importantes limitaciones.

Vida académica de la facultad

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Facultad de Medicina Revista

1999-07-01

Full Text Available Enciclopedia Académica sobre el Lenguaje en las Ciencias de la Salud / Convenio con la Universidad de Alcalá de Henares / Libro de Biología / XI Congreso de actualización en Rehabilitación Médica. Dolor crónico, diagnóstico y manejo integral / Primer Congreso Latinoamericano de Estudiantes de Nutrición y Dietética

Gestão econômica de investimentos em ativos fixos

OpenAIRE

Catelli,Armando; Parisi,Cláudio; Santos,Edilene Santana

2003-01-01

Num ambiente global de intensas mudanças competitivas, a mensuração dos ativos, especificamente dos ativos fixos, requer a superação da rigidez dos custos históricos e da depreciação linear, próprios da contabilidade tradicional, e a adoção de critérios que permitam avaliar adequadamente a realidade econômica desses ativos. Partindo da premissa de que o patrimônio líquido deve representar o valor da empresa, e de que sua variação expressa o resultado econômico, o Sistema de Gestão Econômica -...

Modelagem de uma unidade de produção para caprinos leiteiros utilizando a dinâmica de sistemas

OpenAIRE

Guimarães, Vinicius Pereira

2007-01-01

O trabalho foi desenvolvido buscando abordar as características de dinâmica, complexidade e inter- relacionamento de um sistema de produção de caprinos. Buscou-se, através da metodologia de modelagem e simulação Dinâmica de Sistemas, identificar o impacto na dinâmica e rentabilidade econômica de rebanhos caprinos leiteiros provocados por modificações no manejo reprodutivo, mortalidade, qualidade do alimento e na idade para o início da vida reprodutiva em cabritas. Buscou-se também avaliar a u...

PODOLSKY'S ELECTRODYNAMICS UNDER A CHIRAL APPROACH ELECTRODINÁMICA DE PODOLSKY BAJO UN ENFOQUE QUIRAL

OpenAIRE

Héctor Torres-Silva

2008-01-01

In this paper we show that a new approach leads to Maxwell's and Podolsky's electrodynamics, provided we start from chiral constitutive relations instead of the usual Coulomb's law.En este trabajo se muestra que un nuevo esquema conduce a la electrodinámica de Maxwell y a la electrodinámica de Podolsky, partiendo con relaciones constitutivas quirales en lugar de la usual ley de Coulomb.

La polémica del nacionalismo

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Germán Posada

1961-10-01

Full Text Available La polémica empezó con el artículo de Hernando Téllez, hace veinte días. Con el pretexto de defender a los escritores de su propia generación, a quienes, según él, se viene acusando sistemáticamente de producir una literatura desarraigada y ausente de la vida nacional, Téllez se lanzó a combatir las teorías de " nacionalismo literario'' que actualmente se agitan en Colombia.

Dinámica económica e institucionalización de la tributación directa. Trasnformaciones institucionales el caso de administración de impuestos 1920-1935

OpenAIRE

Oscar Rodríguez Salazar

1999-01-01

Las tres primeras décadas del presente siglo son el escenario de profundas transformaciones en la estructura económica del país y en el modelo institucional. El desarrollo de la economía cafetera, el acceso a la economía de crédito internacional, los cambios en la política económica, la ampliación de la infraestructura, el acelerado proceso de urbanización, los cambios demográficos, la proletarización de un contingente considerable de masas campesinas y el inicio del proceso de industrializac...

Rare earth ion controlled crystallization of mica glass-ceramics

International Nuclear Information System (INIS)

Garai, Mrinmoy; Karmakar, Basudeb

2016-01-01

In understanding the effects of rare earth ions to control the crystallization and microstructure of alkaline boroaluminosilicate system, the CeO_2, Nd_2O_3, Sm_2O_3 and Gd_2O_3 doped K_2O−MgO−B_2O_3−Al_2O_3−SiO_2−F glasses were synthesized by melt-quenching at 1550 °C. Higher density (2.82–3.06 g cm"−"3) and thermal stability (glass phase) is experiential on addition of rare earth content, which also affects in increasing the glass transition temperature (T_g) and crystallization temperature (T_c). Decrease of thermal expansion in glasses with rare earth ion content is maintained by the stabilization of glass matrix owing to their large cationic field strength. A significant change in the non-isothermal DSC thermogram observed at 750–1050 °C is attributed to fluorophlogopite crystallization. Opaque glass-ceramics were prepared from such glasses by single step heat-treatment at 1050 °C; and the predominant crystalline phases are identified as fluorophlogopite mica, KMg_3(AlSi_3O_1_0)F_2 by XRD and EDX analysis. The compact glass-ceramic microstructure by the agglomeration of fluorophlogopite mica crystallites (crystal size ∼ 100–500 nm, FESEM) is achieved in attendance of rare earth ion; and such microstructure controlled the variation of density, thermal expansion and microhardness value. Higher thermal expansion (11.11–14.08 × 10"−"6/K at 50–800 °C and 50–900 °C) of such glass-ceramics approve that these rare earth containing glasses can be useful for high temperature vacuum sealing application with metal or solid electrolyte. The increase of Vickers microhardness (5.27–5.61 GPa) in attendance of rare earth ions is attributed to the compact crystallinity of fluorophlogopite mica glass-ceramic microstructure. - Highlights: • Synthesis of rare earth oxide doped alkaline boroaluminosilicate glasses. • Development of opaque fluorophlogopite mica glass-ceramics by single-step heat treatment. • Nanocrystalline glass

Daniel Kahneman y la Psicología Económica

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ISMAEL QUINTANILLA

2002-01-01

Full Text Available La reciente concesión del Premio Nobel de Economía a un psicólogo, aunque no sea cosa nueva, puede ser un excelente motivo de reflexión científica y de consideración profesional. La psicología ha estado demasiado tiempo alejada de lo que podría denominarse la conducta social más consuetudinaria, la que componen nuestras decisiones económicas y nuestras conductas como consumidores. No ha sido este un campo que haya gozado de muchas simpatías por parte de nuestros colegas. Quizá como consecuencia de una visión excesivamente estrecha de las posibilidades explicativas y aplicativas de la Psicología Económica. Puede que también se deba a un cierto desconocimiento de esta especialidad -o campo de investigación y desarrollo- de la Psicología social. De hecho, apenas existente como materia de estudios en las Facultades de psicología españolas cuando es cosa bastante corriente en la mayor parte de las europeas (Webley y Walker, 1999. El artículo resume y sintetiza los resultados de las investigaciones de la concesión del Premio Nobel de Economía a Vernon Smith y David Kahneman, reflexiones en base al futuro de la psicología Económica.

Parte 4: Estudio comparativo de la composición química

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L. R. Carballo-Abreu

2004-01-01

Full Text Available Se estudió comparativamente, mediante análisis estadístico la composición química de la madera de E. saligna Smith, Corymbia citriodora y E. pellita F. Muell, a tres alturas del fuste comercial (25, 55 y 85 % en muestras procedentes de las Empresas Forestales Integrales (EFI de Macurije y Guanahacabibes en la provincia de Pinar del Río, Cuba. Los resultados obtenidos de la composición química, se trataron mediante un programa estadístico SPSS para Windows, donde no todas las variables analizadas muestran influencias estadísticas en la caracterización química de las especies. Los resultados manifiesta una mejor agrupación con especto a la especie que a la altura del fuste comercial entre las especies. La madera de Corymbia citriodora presenta los mayores contenidos de celulosa, los menores contenidos de lignina y de sustancias extraíbles, siendo la especie más atractiva desde el punto de vista químico para ser utilizada en la Industria de celulosa y papel.

Los nuevos dominios de la ciencia económica

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Bejarano Jesús Antonio

1999-12-01

Full Text Available Hace algo más de diez años, siendo Decano de la Facultad de Ciencias Económicas de la Universidad Nacional, tuve el honor de ser el primer expositor en el primer congreso de estudiantes de economía del país. Once años después, recae de nuevo en mí ese honor, y por ello debo expresar mi gratitud a los estudiantes organizadores de este cuento. Entre aquel primer congreso y éste se transformó no sólo el panorama del quehacer profesional sino también el panorama global de la ciencia económica, y creo que en forma radical. En poco más de veinte años, desde comienzos de los años setenta, se abrieron nuevos rumbos que, sin duda, quienes hoy son estudiantes seguirán en el futuro.

La disponibilidad de nutrientes para las plantas, consecuencia de interacción, química, biológica y bioquímica

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Martha Medina

2007-10-01

Full Text Available La nutrición vegetal depende de varios factores;entre ellos: minerales, microorganismos y moléculas orgánicas. Éstos a la vez están relacionados con las condiciones físicas, químicas y biológicas del suelo. Las adiciones de materia orgánica o de abonos orgánico-minerales favorecen esta condición, porque, contienen moléculas que alimentan poblaciones microbianas que segregan las enzimas requeridas para solubilizar minerales o mineralizarla, pero no suplen las necesidades de la mayoría de los cultivos. Esta dinámica está determinada por la presencia de elementos que intervienen en la fijación del nitrógeno o la producción de ácidos orgánicos que liberan fósforo, pero que también pueden afectar la biodisponibilidad de varios nutrientes o las poblaciones microbianas.

Plagio e integridad académica en Alemania

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2016-07-01

Full Text Available Alemania es quizá uno de los países europeos que, ya desde el siglo XVIII, ha mantenido un debate público más intenso sobre prácticas científicas y académicas deshonestas, relacionadas especialmente con tesis doctorales. Este debate fue especialmente productivo a finales del siglo XIX, dando lugar desde entonces, para evitar estas prácticas inaceptables, a la obligatoriedad de publicar todas las tesis doctorales, como requisito previo a la expedición del título de doctor por cualquier universidad alemana. Este trabajo analiza los avances más importantes en plagio e integridad académica en Alemania, especialmente después del escándalo surgido en 2011 a raíz del plagio de la tesis doctoral del Ministro de Defensa Guttenberg, como son la creación de una eficaz metodología colaborativa de investigación del plagio en trabajos científicos o académicos utilizando Internet y las redes sociales, materializada en la Wiki «VroniPlag». También se describe someramente en este trabajo la consolidación definitiva de la figura del «Defensor de la Ciencia», como instrumento de ámbito nacional para prevenir, gestionar y combatir la deshonestidad científica, aparte de la publicación en 2013 de una nueva versión del manual de referencia al respecto «Sicherung guter wissenschaftlicher Praxis». Por último se analizan las conclusiones de la experiencia alemana relacionada con la ética académica, también desde una perspectiva histórica, pues sus recientes logros y avances pueden servir de referencia a otros países europeos.

The crystal orientation relation and macroscopic surface roughness in hetero-epitaxial graphene grown on Cu/mica

International Nuclear Information System (INIS)

Qi, J L; Nagashio, K; Nishimura, T; Toriumi, A

2014-01-01

Clean, flat and orientation-identified graphene on a substrate is in high demand for graphene electronics. In this study, the hetero-epitaxial graphene growth on Cu(111)/mica(001) by chemical vapor deposition is investigated to check the applicability for top-gate insulator research on graphene, as well as graphene channel research, by transferring graphene on to SiO 2 /Si substrates. After adjusting the graphene growth conditions, the surface roughness of the graphene/Cu/mica substrate and the average smoothed areas are ∼0.34 nm and ∼100 μm 2 , respectively. The orientation of graphene in the graphene/Cu/mica substrate can be identified by the hexagonal void morphology of Cu. Moreover, we demonstrate a relatively high mobility of ∼4500 cm 2 V −1 s −1 in graphene transferred on the SiO 2 /Si substrate. These results suggest that the present graphene/Cu/mica substrate can be used for top-gate insulator research on graphene. (papers)

CULTURAS ACADÉMICAS: ENTRE REINVENCIÓN Y CONTRABANDO

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Kathya Araujo

2015-01-01

Full Text Available Sobre la base del análisis de una historia personal de desplazamiento entre academias (peruana y chilena, y la reinvención y el contrabando que toda migración supone, este artículo argumenta de qué manera frente a las nuevas modalidades de evaluación (los rankings, la búsqueda de isomorfismo de las estructuras argumentativas y las formas lingüísticas o incluso la ficción de sociologías globales, se mantienen vivas culturas académicas particulares. En este marco, la reflexión se organiza mostrando que detrás de la singularidad de los estilos intelectuales, formas de sociabilidad profesionales e incluso formas lingüísticas de cada una de ellas, lo que se revela es la manera en la que cada cultura académica local responde desde tradiciones diversas a desafíos político sociales distintos y con ello su rol de compromiso público y crítico.

PODOLSKY'S ELECTRODYNAMICS UNDER A CHIRAL APPROACH ELECTRODINÁMICA DE PODOLSKY BAJO UN ENFOQUE QUIRAL

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Héctor Torres-Silva

2008-11-01

Full Text Available In this paper we show that a new approach leads to Maxwell's and Podolsky's electrodynamics, provided we start from chiral constitutive relations instead of the usual Coulomb's law.En este trabajo se muestra que un nuevo esquema conduce a la electrodinámica de Maxwell y a la electrodinámica de Podolsky, partiendo con relaciones constitutivas quirales en lugar de la usual ley de Coulomb.

Rutas Gastronómicas y Desarrollo local: un ensayo de conceptualización en Cataluña

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Zeinab Jeambey

2016-01-01

Full Text Available Las rutas gastronómicas estimulan el desarrollo local sostenible de zonas agrícolas, atrayendo hacia ellas un turismo de calidad. Cataluña promociona varias rutas gastronómicas que, sin embargo, carecen de estructura y contenido coherente. En este trabajo, se consultó a expertos en el ámbito de turismo y gastronomía sobre su percepción de lo que debe ser una ruta gastronómica que contribuya al desarrollo local. Según ellos, no existen en Cataluña pautas que rijan su diseño y funcionamiento. Una ruta gastronómica se define como un producto turístico estructurado que contribuye al mantenimiento del paisaje, la difusión de la cultura local, el desarrollo económico y el posicionamiento del territorio. Clave para su éxito es su organización, la coherencia del discurso y las responsabilidades de los agentes involucrados. Se valora el papel del productor. Se recomienda la estandarización de la definición de ruta gastronómica y la elaboración de pautas para su diseño y su estructuración.

Política econômica e Estado Economic policy and State

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Giovani Clark

2008-04-01

Full Text Available O artigo enfoca, pela óptica do direito econômico, as influências das políticas econômicas privadas (basicamente do capital transnacional e dos entes internacionais sobre as políticas econômicas públicas, especialmente as realizadas pelos Estados em desenvolvimento. Enfatiza a mutação do neoliberalismo de regulamentação para o de regulação como exigência dos poderes econômicos privados, identificando entre os seus resultados o enfraquecimento do Estado e a descrença na democracia. E, ainda, defende a existência de espaços para a execução de ações econômicas endógenas por parte dos Estados Nacionais, a fim de viabilizar a eficácia de suas Constituições econômicas e suprir as carências de seus povos.This paper deal with, by Economical Law view, the effects of private economic policy, essentially of foreign capital, and the international organizations above the public economic policy, mainly that politics performed by the development nations. Lay emphasis on the mutation of the regulatory New Liberalism to the regulation as demand of private economic powers, recongnized enter their results: The decline of the State and the unbelief of democracy. Defends existence of spaces for the execution of endogenous economic actions by part of National States, for the purpose of execute effectiveness of their economical constitution and supply the shortage of their people.

Economic policy and state Política econômica e estado

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Giovani Clark

2007-12-01

Full Text Available This paper deal with, by Economical Law view, the effects of private economic policy, essentially of foreign capital, and the international organizations above the public economic policy, mainly that politics performed by the development nations. Lay emphasis on the mutation of the regulatory New Liberalism to the regulation as demand of private economic powers, recongnized enter their results: The decline of the State and the unbelief of democracy. Defends existence of spaces for the execution of endogenous economic actions by part of National States, for the purpose of execute effectiveness of their economical constitution and supply the shortage of their people.O artigo enfoca, pela ótica do Direito Econômico, as influências das políticas econômicas privadas (basicamente do capital transnacional e dos entes internacionais sobre as políticas econômicas públicas, principalmente as realizadas pelos Estados em desenvolvimento. Enfatiza a mutação do Neoliberalismo de Regulamentação para o de Regulação como exigência dos poderes econômicos privados, identificando entre os seus resultados: o enfraquecimento do Estado e a descrença na Democracia. E ainda, defende a existência de espaços para a execução de ações econômicas endógenas por parte dos Estados nacionais, a fim de viabilizar a eficácia de suas Constituições Econômicas e suprir as carências de seus povos.

Uma abordagem investigativa do trabalho experimental no ensino da química a alunos não-químicos na universidade

OpenAIRE

Figueiredo, Margarida; Maia, Maria Elisa

2005-01-01

Pretende-se divulgar os resultados de um estudo sobre a implementação de um tipo de abordagem ao Trabalho Experimental de Química, cujos objectivos são: - Contribuir para motivar os alunos para a aprendizagem da Química; - Contribuir para melhorar o sucesso na formação em Química dos alunos que não sendo de Química necessitam de fazer aprendizagens nesse domínio; - Contribuir para uma revalorização do trabalho experimental enquanto estratégia privilegiada para o ensino da Química....

SEMIÓTICA E MORFODINÂMICA. UMA BUSCA E SUAS VICISSITUDES

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Ivã Carlos Lopes

2014-07-01

Full Text Available Entre as discussões que marcaram a breve história da semiótica desde os princípios de sua implantação disciplinar, focalizamos, nesta ocasião, as chamadas propostas "morfodinâmicas" que, na comunidade semiótica, tiveram curso principalmente durante as décadas de 1980 e 1990, até se tornarem menos frequentadas a partir da virada do novo século. A fim de ilustrar nossa explanação, mostramos o modo de funcionamento de uma esquematização morfodinâmica das modalidades epistêmicas, lidas com auxílio de uma das "catástrofes elementares" de René Thom, debatendo sua contribuição para a inteligibilidade dessa região conceitual

Compensaciones económicas ante conflictos de uso del suelo

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Polanco Jorge Andrés

2009-10-01

Full Text Available Existen conflictos de uso del suelo que pretenden ser atenuados con compensaciones económicas. En este trabajo se estiman los conflictos existentes en el Sistema de Páramos Alto-Andinos de Antioquia, comparando las restricciones al uso del suelo con la dinámica de la frontera agropecuaria. Las compensaciones se calculan en función de la renta de la tierra y se evalúa su financiación con recursos públicos y privados considerando las inversiones municipales y la solvencia del sector productivo. Los resultados muestran que los conflictos son mayores donde la frontera es activa. Las compensaciones logran ser asumidas por los municipios pequeños con tierras poco rentables, mientras que los grupos económicos pueden financiarlas dependiendo de la gobernanza.

Morfoanatomia e histoquímica de Brosimum gaudichaudii Trécul (Moraceae)

OpenAIRE

Jacomassi,Ezilda; Moscheta,Ismar Sebastião; Machado,Sílvia Rodrigues

2007-01-01

Brosimum gaudichaudii, conhecida como mamacadela, é espécie comum nos cerrados, com grande valor na medicina popular e na indústria de medicamentos. A casca da raiz e do caule é empregada no tratamento do vitiligo, sendo o bergapteno e psoraleno, duas furanocumarinas, responsáveis pela ação farmacológica. Neste trabalho são apresentadas a caracterização morfoanatômica e a histoquímica de órgãos vegetativos de B. gaudichaudii, com informações sobre o embrião e o desenvolvimento pós-seminal. Am...

Apuntes de historia de la química industrial en México

OpenAIRE

Bucay, Benito

2001-01-01

La química industrial en México desciende de las actividades mineras de la época de la Colonia. Su despegue ocurre durante la Segunda Guerra Mundial y tiene un fuerte desarrollo en varios frentes entre 1960 y 1990. A partir de entonces, se ha dado un proceso de consolidación y reestructura como consecuencia de la apertura económica, lo cual ha conducido a una reducción en el número de participantes y actividades, quedando sólo aquéllas que tienen una base firme de tecnología y capacidad que l...

Estabilidad del color de las cerámicas de disilicato de litio.

OpenAIRE

Cedeño Salazar, Rosario

2016-01-01

La gran demanda de tratamientos estéticos por parte de los pacientes, supone un reto para los rehabilitadores orales, por lo que siempre están en búsqueda del material ideal. Las cerámicas dentales, poseen características que le permiten mimetizar la apariencia de los dientes naturales, por sus propiedades físicas y químicas, las cuales dependen de su composición. Poseen una fase vítrea que le aporta características estéticas y una fase cristalina que le aporta propiedades mecánicas. Clín...

Redes empresariales y estabilidad macroeconómica : una propuesta teórica.

OpenAIRE

Rodríguez Oviedo, Gilberto José

2016-01-01

En esta tesis se hace una revisión de la concentración empresarial así como su afectación al mercado. Se revisa el concepto de redes en el contexto de recesión económica, y algunos tipos de equilibrio general como los macroeconómicos, de generaciones traslapadas y los computables. Con esta introducción se hace un breve análisis de algunos modelos de equilibrio general realizados para el Ecuador en diversas áreas de aplicación como impuestos, comercio exterior, protección económica y social. C...

Insuficiencia dinámica, crecimiento y desempleo en México, 1974-2012

OpenAIRE

Blanca L. Avendaño Vargas; Ignacio Perrotini Hernández

2015-01-01

El artículo presenta una reformulación de la hipótesis de insuficiencia dinámica de Prebisch (1970), analiza la teoría dinámica de Harrod (1939), la ley Kaldor-Verdoorn (Kaldor, 1966; 1967) y la teoría del crecimiento endógeno de Thirlwall (1969; 2000). A posterioriestudiamos los determinantes del crecimiento económico y del desempleo en México durante el periodo 1974-2012. Con base en el análisis empírico, sostenemos que una baja tasa de acumulación genera una reducida absorción de empleo, u...

Dinámica de sistemas en la gestión de inventarios

OpenAIRE

Daniel Alejandro Agudelo Serna; Yohana Marcela López Rivera

2018-01-01

En el presente artículo se estudia el proceso de gestión de inventarios por medio de la dinámica de sistemas, como herramienta metodológica que permite conocer el comportamiento de las variables de acuerdo a sus relaciones y a las decisiones que se tomen teniendo en cuenta su causalidad y realimentación. El desarrollo del documento está determinado por una revisión de conceptos teóricos relacionados con la gestión de inventarios y dinámica de sistemas, seguido por una revisión de lit...

AVALIAÇÃO ECONÔMICA DO TRÁFICO DE DROGAS NO ESTADO DO ACRE

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Rennan Bitts de Lima Lima

2011-09-01

Full Text Available A decisão de um indivíduo em migrar para a atividade econômica criminosa do tráfico de drogas é influenciada por um conjunto de características econômicas e sociais. Diante disso, levando-se em conta que o tráfico de drogas está relacionado à prática de uma grande quantidade de outros crimes, a proposta deste trabalho consiste na produção de informações que sirvam de subsídio para ações de agentes públicos e privados que visem combater a criminalidade. De forma geral, o objetivo deste trabalho consiste em fazer uma avaliação socioeconômica do crime de tráfico de drogas no Estado do Acre. Especificamente, pretende-se: i realizar uma análise econômica e financeira do tráfico de drogas e, ii identificar quais são os fatores comuns entre as pessoas que migram para esta atividade criminosa. Assim, pôde-se constatar que o indivíduo considera a atividade do tráfico de drogas de grande risco, contudo, sua alta lucratividade a torna atrativa.

Dinámica migratoria... ¿hibridación cultural u homologación global?

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Claudia Carolina Zamorano Villarreal

2014-01-01

Full Text Available Ante la consolidación del modelo de subcontratación en México asistimos a una nueva cultura laboral ¿Qué cambios ha impulsado este modelo en las prácticas de la pobla - ción y su cultura? Analizando la relación entre el modo de producción flexible de la maquila y la dinámica de migración propia a las ciudades de la frontera norte de Mé - xico, se muestra que la maquiladora respetó y aprovechó está dinámica para reducir o aumentar el número de trabajadores, según lo requiriera la producción flexible. Pero, desde mediados de los años noventa, empezó a transformar estás dinámicas y con ellas, la cultura de sus trabajadores.

Comunidades virtuales y producción de inteligencia económica y competitiva

OpenAIRE

Carvalho, Andrea Vasconcelos

2007-01-01

CARVALHO, Andréa Vasconcelos . Comunidades virtuales y producción de inteligencia económica y competitiva. Inteligencia y Seguridad: revista de análisis y prospectiva, v. 3, p. 13-45, 2007 Se defiende que las comunidades virtuales ofrecen información útil para la generación de inteligencia económica y competitiva. Así, se identifican y describen las principales aplicaciones de las comunidades virtuales para la producción de estos tipos de inteligencia. Sin embargo, no se disponen...

Femtoquímica: reacciones en tiempo real, ?`Posibles aplicaciones en Astrofísica?

Science.gov (United States)

Douhal, Abderrazzak

En esta conferencia, se mostrarán resultados de medidas en escala del femtosegundo por la primera vez obtenidos en España. Los sistemas elegidos muestran dinámicas que varían de 50 fs a centenas de picosegundo. La técnica usada (sumación de frecuencia) permite ver como ocurren las reacciones químicas y biológicas en tiempo real de reacciones. Su aplicación al estudio de las reacciones fotónicas en el espacio es evidente.

Proteômica quantitativa e metabolômica do híbrido Eucalyptus grandis x E. camaldulensis, tolerante e susceptível ao déficit hídrico

OpenAIRE

Janaina de Santana Borges

2016-01-01

O E. grandis x E. camaldulensis possui características favoráveis de adaptação à seca, conferidas pelo E. camaldulensis e qualidade da madeira para papel e celulose, conferida pelo E. grandis. Esta adaptação à seca está relacionada a fatores fisiológicos e também moleculares, expressos em sua proteoma e metaboloma, que se alteram na presença do estresse. Objetiva-se neste trabalho estudar as respostas fisiológicas, proteômicas e metabolômicas (metabólitos primários) diferencialmente expressos...

VULNERABILIDAD SOCIAL Y DINÁMICA DEMOGRÁFICA EN ARGENTINA, 2001-07

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Leandro M. González

2009-01-01

Full Text Available En este artículo se indaga acerca de la evolución social de la República Argentina con posterioridad a la crisis socioeconómica de fines del año 2001 y considerar la persistencia de los riesgos en los años posteriores. Se analizan los principales rasgos sociales (pobreza y empleo y demográficos (fecundidad y mortalidad, para el total nacional y seis provincias de diversas regiones geográficas. La crisis socioeconómica produjo un inédito grado de empobrecimiento (55% en 2002. Las diferencias regionales se mantuvieron a lo largo del período de análisis, debido al carácter estructural que revisten. La reactivación económica del período 2003- 2007 mejoró los niveles de ingresos y empleo, aunque se registra el estancamiento en la esperanza de vida, aumentos de las tasas de mortalidad infantil y materna, e incremento continuo de la fecundidad adolescente. Se propone la hipótesis de que en la República Argentina la vulnerabilidad social es de carácter estructural y permanente, a pesar de las reducciones en las tasas de pobreza y desempleo.

Ultrasensitive tunability of the direct bandgap of 2D InSe flakes via strain engineering

Science.gov (United States)

Li, Yang; Wang, Tianmeng; Wu, Meng; Cao, Ting; Chen, Yanwen; Sankar, Raman; Ulaganathan, Rajesh K.; Chou, Fangcheng; Wetzel, Christian; Xu, Cheng-Yan; Louie, Steven G.; Shi, Su-Fei

2018-04-01

InSe, a member of the layered materials family, is a superior electronic and optical material which retains a direct bandgap feature from the bulk to atomically thin few-layers and high electronic mobility down to a single layer limit. We, for the first time, exploit strain to drastically modify the bandgap of two-dimensional (2D) InSe nanoflakes. We demonstrated that we could decrease the bandgap of a few-layer InSe flake by 160 meV through applying an in-plane uniaxial tensile strain to 1.06% and increase the bandgap by 79 meV through applying an in-plane uniaxial compressive strain to 0.62%, as evidenced by photoluminescence (PL) spectroscopy. The large reversible bandgap change of ~239 meV arises from a large bandgap change rate (bandgap strain coefficient) of few-layer InSe in response to strain, ~154 meV/% for uniaxial tensile strain and ~140 meV/% for uniaxial compressive strain, representing the most pronounced uniaxial strain-induced bandgap strain coefficient experimentally reported in 2D materials. We developed a theoretical understanding of the strain-induced bandgap change through first-principles DFT and GW calculations. We also confirmed the bandgap change by photoconductivity measurements using excitation light with different photon energies. The highly tunable bandgap of InSe in the infrared regime should enable a wide range of applications, including electro-mechanical, piezoelectric and optoelectronic devices.

Introducing LIR (Lithotheque Ireland, a reference collection of flaked stone tool raw materials from Ireland

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Killian Driscoll

2016-09-01

Full Text Available The LIR (Lithotheque Ireland reference collection of flaked stone tool raw materials from Ireland began in 2013, and is based on the geological prospection from two projects. The first (2013-2015 focused attention primarily on Carboniferous cherts from the northwest of Ireland, collecting 405 samples. The second (2015-2017 is currently collecting samples of the Cretaceous flint primarily from in situ contexts in the northeast of Ireland, but also includes beach surveys of Cretaceous flint from around the island; the first phase of geological prospection in Autumn 2015 collected 239 samples, with the geological prospection continuing in 2016. Therefore, to date the collection contains over 600 hand samples of chert and flint, along with a small number of other materials (siliceous limestone, tuff, mudstone. The physical reference collection is housed at the UCD School of Archaeology, University College Dublin and contains the geological hand samples along with the various thin sections of the samples that are used for petrographic analysis. The physical collection is complemented by an online database that is to be used alongside the physical collection, or can be used as a stand-alone resource. This paper provides an overview of the database’s metadata and the processes of data entry and editing, to serve as a reference point for the database and the fieldwork undertaken to date, and to serve as a template for other researchers undertaking similar work on lithic reference collections.

AVALIAÇÃO DA ROTULAGEM, CARACTERIZAÇÃO QUÍMICA, FÍSICO-QUÍMICA E REOLÓGICA DE NÉCTARES DE UVA COMERCIALIZADOS NA CIDADE DE FORTALEZA - CE

OpenAIRE

Alessandra Pinheiro de Góes CARNEIRO; David Araujo ABREU; Denise Josino SOARES; Eveline de Alencar COSTA; Larissa Morais Ribeiro da SILVA; Lívia Carvalho BARBOSA; Paulo Henrique Machado de SOUSA; Raimundo Wilane de FIGUEIREDO

2013-01-01

No Brasil, há diferentes tipos de bebidas de frutas, dentre elas pode-se citar o suco e o néctar, que, de acordo com a legislação brasileira diferem entre si na quantidade de polpa de fruta que é adicionada em cada formulação, sendo o néctar a bebida com menor proporção de polpa de fruta. O objetivo do presente trabalho foi avaliar diferentes marcas comerciais de néctar de uva quanto às características de rotulagem, propriedades químicas, físico-químicas e reológicas. ...

Conflicto armado, variables socio-económicas y formación ciudadana: un análisis de impacto

OpenAIRE

Marieta Quintero-Mejía; Sara Victoria Alvarado; Juan Carlos Miranda

2016-01-01

En este artículo buscamos exponer los efectos que tienen las condiciones socio- económicas y el conflicto armado sobre los aprendizajes ciudadanos. Para ello, adoptamos un enfoque cuantitativo que nos permitió analizar cómo las condiciones económicas, sociales y de conflicto armado determinan el desarrollo de Competencias Ciudadanas. Lo anterior nos llevó a establecer que las variables socio-económicas tienen un impacto mayor en el desarrollo de acciones, actitudes y emociones favorables, mie...

[Machinable property of a novel dental mica glass-ceramic].

Science.gov (United States)

Chen, Ji-hua; Li, Na; Ma, Xin-pei; Zhao, Ying-hua; Sun, Xiang; Li, Guang-xin

2007-12-01

To investigate the machinability of a novel dental mica glass-ceramic and analyze the effect of heat-treatment on its ductile machinable behavior. The drilling and turning experiment were used to measure the machinabilities of the control group (feldspar ceramic: Vita Mark II) and 7 experiment groups treated with different crystallization techniques. The microstructures were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The average drilling depths in 30 s of the experimental groups ranged from (0.5 +/- 0.1) mm to (7.1 +/- 0.8) mm. There were significant differences between the control [(0.8 +/- 0.1) mm] and the experimental groups (P machining at a high velocity and cut depth. The crystal portion of this group is only about 40%. This material has a satisfactory machinability. The mechanism could be attributed to a combination of the interlocked structure of mica crystals and the low viscosity of glassy phase.

Un nuevo enfoque didáctico para acercar la Electroquímica al alumnado a través de experiencias cotidianas

OpenAIRE

Arán-Ais, Rosa M.; Busó-Rogero, Carlos; Chumillas, Sara; Climent, Víctor; Herrero, Enrique; Aldaz Riera, Antonio; Feliu, Juan M.

2013-01-01

La electroquímica es una parte importante de la química, incluida en la mayoría de los temarios de diversas ciencias experimentales. Las reacciones químicas con transferencia de electrones aparecen en numerosas situaciones de la vida cotidiana y constituyen un aspecto muy importante en las reacciones biológicas. A pesar de su importancia, la electroquímica suele ser percibida por los estudiantes con dificultad pues incluye conceptos algo abstractos, como el de potencial eléctrico, que combina...

Importancia actual de la oleoquímica en el sector industrial de tensioactivos

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Gómez Herrera, Carlos

2009-09-01

Full Text Available Oleochemistry is an industrial sector with various applications and important developments in the field of surfactans. In this article different parts are dedicated to: A Sources of oleochemical raw materials; B Valorization of the oleochemistry in the field of surfactants; C Hydrophilic heads based on carbohydrates or proteins, D Examples of surfactants currently prepared at industrial scale, such as esters of polyols, alkylpolyglucosides, glucamides and lipoaminoacids. Collaboration between industrial sectors of surfactants and oleaginous products has evidenced various strong points. Ecological, energetic, economical and sanitary reasons will probably increase this collaboration in the future.La oleoquímica es un sector industrial con aplicaciones múltiples e importantes desarrollos en el campo de los tensioactivos. En el presente artículo se dedican apartados a: A fuentes de materias primas oleoquímicas, B valorización de la oleoquímica en el campo de los tensioactivos, C partes hidrófilas de los tensioactivos basadas en carbohidratos o en proteínas, D ejemplos de biotensioactivos actualmente preparados a escala industrial, tales como ésteres de polioles, alquilpoliglucósidos, glucamidas, ésteres de sacarosa y lipoaminoácidos. La colaboración entre los sectores industriales de tensioactivos y de productos oleaginosos ha puesto en evidencia numerosos puntos fuertes. Muy probablemente, razones energéticas, económicas, ecológicas y sanitarias harán que esta colaboración se incremente en el futuro.

Geoquímica de solos do pantanal norte, Mato Grosso

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Elaine de Arruda Oliveira Coringa

2014-12-01

Full Text Available A caracterização e análise geoquímica de solos permitem compreender os processos de migração, dispersão e concentração de elementos químicos no perfil, embasando a correlação dos atributos deles com as classes de solos formadas, o que possibilita inferências acerca das gêneses desses solos. Esta pesquisa teve por objetivos caracterizar e interpretar a composição geoquímica total de elementos maiores e menores em classes de solos representativas do Pantanal norte, na sub-região de Barão de Melgaço, Mato Grosso, Brasil. Foram selecionados 20 perfis das principais classes de solos do Pantanal e analisadas amostras dos horizontes A e B (ou C quanto à concentração de óxidos totais por espectrometria de fluorescência de raios-X, além das caracterizações física, química e mineralógica. Os solos subdividiram-se em dois tipos geoquímicos: um composto por textura arenosa a franco-arenosa com teores relativamente elevados de SiO2 e predominância de caulinita e quartzo, com menor teor de bases e elementos-traço; e outro composto por textura mais argilosa, geoquimicamente heterogêneos e com teores significativos de minerais 2:1, Al2O3, óxidos de Fe e Mn, bases e elementos-traço.

Valoración económica de bienes ambientales.

OpenAIRE

Orrego Suaza, Sergio Alonso; Cerda Urrutia, Arcadio; Vásquez Lavín, Felipe

2011-01-01

El trabajo describe los distintos métodos de valoración económica de bienes ambientales y su utilización en estudios de impacto sobre el entorno para obtener estimaciones monetarias de los efectos negativos sobre la calidad ambiental de recursos naturales específicos.

Rutas Gastronómicas y Desarrollo local: un ensayo de conceptualización en Cataluña

OpenAIRE

Zeinab Jeambey

2016-01-01

Las rutas gastronómicas estimulan el desarrollo local sostenible de zonas agrícolas, atrayendo hacia ellas un turismo de calidad. Cataluña promociona varias rutas gastronómicas que, sin embargo, carecen de estructura y contenido coherente. En este trabajo, se consultó a expertos en el ámbito de turismo y gastronomía sobre su percepción de lo que debe ser una ruta gastronómica que contribuya al desarrollo local. Según ellos, no existen en Cataluña pautas que rijan su diseño y fun...

Software Application Profile: Opal and Mica: open-source software solutions for epidemiological data management, harmonization and dissemination.

Science.gov (United States)

Doiron, Dany; Marcon, Yannick; Fortier, Isabel; Burton, Paul; Ferretti, Vincent

2017-10-01

Improving the dissemination of information on existing epidemiological studies and facilitating the interoperability of study databases are essential to maximizing the use of resources and accelerating improvements in health. To address this, Maelstrom Research proposes Opal and Mica, two inter-operable open-source software packages providing out-of-the-box solutions for epidemiological data management, harmonization and dissemination. Opal and Mica are two standalone but inter-operable web applications written in Java, JavaScript and PHP. They provide web services and modern user interfaces to access them. Opal allows users to import, manage, annotate and harmonize study data. Mica is used to build searchable web portals disseminating study and variable metadata. When used conjointly, Mica users can securely query and retrieve summary statistics on geographically dispersed Opal servers in real-time. Integration with the DataSHIELD approach allows conducting more complex federated analyses involving statistical models. Opal and Mica are open-source and freely available at [www.obiba.org] under a General Public License (GPL) version 3, and the metadata models and taxonomies that accompany them are available under a Creative Commons licence. © The Author 2017; all rights reserved. Published by Oxford University Press on behalf of the International Epidemiological Association

The MICA Case Conference Program at Tewksbury Hospital, Mass.: an integrated treatment model.

Science.gov (United States)

Clodfelter, Reynolds C; Albanese, Mark J; Baker, Gregg; Domoto, Katherine; Gui, Amy L; Khantzian, Edward J

2003-01-01

This report describes the MICA (Mentally Ill Chemically Abusing) Program at the Tewksbury Hospital campus in Tewksbury, Massachusetts. Several campus facilities collaborate in the MICA Program. Through Expert Case Conferences, principles of integrated psychosocial treatment with dual diagnosis patients are demonstrated. An expert clinician focuses on the interplay between psychological pain, characterological traits, defenses, and the patient's drug of choice. Patients who have participated in the program have reported positive experiences. The staff reported that the program has resulted in facility improvement in assessment and treatment of complex dual diagnosis patients.