The Microwave-assisted Synthesis of Polyethersulfone (PES as A Matrix in Immobilization of Candida antarctica Lipase B (Cal-B

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Khusna Widhyahrini

2017-10-01

How to Cite: Widhyahrini, K., Handayani, N., Wahyuningrum, D., Nurbaiti, S., Radiman, C.L. (2017. The Microwave-assisted Synthesis of Polyethersulfone (PES as A Matrix in Immobilization of Candida antarctica Lipase B (Cal-B. Bulletin of Chemical Reaction Engineering & Catalysis, 12(3: 343-350 (doi:10.9767/bcrec.12.3.774.343-350

Characterization of morphology controlled polyethersulfone hollow fiber membranes by the addition of polyethylene glycol to the dope and bore liquid solution

NARCIS (Netherlands)

Koops, G.H.; Liu, Y.; Liu, Y.; Strathmann, H.

2003-01-01

The preparation of polyethersulfone (PES) hollow fiber membranes has been studied using N-methylpyrrolidone (NMP) as solvent, polyethylene glycol 400 (PEG 400) as weak nonsolvent and water as strong nonsolvent. When PEG 400 is used as polymeric additive to the spinning dope the viscosity of the PES

Versatile antifouling polyethersulfone filtration membranes modified via surface grafting of zwitterionic polymers from a reactive amphiphilic copolymer additive.

Science.gov (United States)

Zhao, Yi-Fan; Zhang, Pei-Bin; Sun, Jian; Liu, Cui-Jing; Yi, Zhuan; Zhu, Li-Ping; Xu, You-Yi

2015-06-15

Here we describe the development of versatile antifouling polyethersulfone (PES) filtration membranes modified via surface grafting of zwitterionic polymers from a reactive amphiphilic copolymer additive. Amphiphilic polyethersulfone-block-poly(2-hydroxyethyl methacrylate) (PES-b-PHEMA) was beforehand designed and used as the blending additive of PES membranes prepared by phase inversion technique. The surface enriched PHEMA blocks on membrane surface acted as an anchor to immobilize the initiating site. Poly(sulfobetaine methacrylate) (PSBMA) were subsequently grafted onto the PES blend membranes by surface-initiated atom transfer radical polymerization (SI-ATRP). The analysis of surface chemistry confirmed the successful grafting of zwitterionic PSBMA brushes on PES membrane surface. The resulted PES-g-PSBMA membranes were capable of separating proteins from protein solution and oil from oil/water emulsion efficiently. Furthermore, the modified membranes showed high hydrophilicity and strongly antifouling properties due to the incorporation of well-defined PSBMA layer. In addition, the PES-g-PSBMA membranes exhibited excellent blood compatibility and durability during the washing process. The developed antifouling PES membranes are versatile and can find their applications in protein filtration, blood purification and oil/water separation, etc. Copyright © 2015 Elsevier Inc. All rights reserved.

Enhancement of polyethersulfone (PES) membrane performance by modification with rice husk nanosilica for removal of organic matter in water

Science.gov (United States)

Mulyati, S.; Armando, M. A.; Mawardi, H.; Azmi, F. A.; Pratiwi, W. P.; Fadzlina, A.; Akbar, R.; Syawaliah

2018-03-01

This paper reports the effects of rice husk nanosilica addition on the performance of polyethersulfone (PES) membrane. Polyethersulfone membrane (PES) was fabricated by using N-methyl-2-pyrolidone (NMP) as a solvent and rice husk nanosilica as a modifying agent. The influence of the rice husk nanosilica additive on the characteristics and performance of the membrane has been studied. Scanning Electron Microscopy (SEM) analysis confirmed that the manufactured membrane has an asymmetric morphological structure consisting of two layers. The upper part of the membrane is a thin layer, meanwhile in the bottom side is a porous layer. The addition of 5% nanosilica resulting a PES membrane to have a bigger porous than that of pristine PES. The pure water flux of nanosilica-modified membranes were greater in comparison to the pure water flux of unmodified PES membrane. The performance of all membranes were evaluated on humic acid removal. The highest selectivity was showcased by pure PES membrane. The introduction of rice husk nanosilica additive to the membrane declined the selectivity of the membrane to humic acid in the feed solution. This is caused by the pores enlargement and enhanced hydrophilicity of the membrane after modification with rice husk biosilica.

Polyethersulfone/Graphene Oxide Ultrafiltration Membranes from Solutions in Ionic Liquid

KAUST Repository

Mahalingam, Dinesh. K.; Kim, DooLi.; Nunes, Suzana. P.

2017-01-01

Novel high flux polyethersulfone (PES) ultrafiltration membranes were fabricated by incorporating different amounts of graphene oxide (GO) sheets to PES as nanofillers. The membranes were prepared from solutions in 50/50 1-ethyl-3-methylimidazolium-diethylphosphate/N,N-dimethyl formamide. It was observed that the water permeance increased from 550 to 800 L m-2h-1bar-1, with incorporation of 1 wt% GO, keeping a molecular weight cut-off (MWCO) of approximately 32-34 kg mol-1. Cross-sectional scanning electron microscopy images of GO/PES membranes showed the formation of ultrathin selective layer unlike pristine membranes. Contact angle measurements confirmed the increase of hydrophilicity, by increasing the GO concentration. The rejection of humic acid and bovine serum albumin was demonstrated. The mechanical properties were improved, compared with the pristine membranes. The performance was just above the trade-off relationship between permeance and separation factor for PES membranes reported in the literature.

Polyethersulfone/Graphene Oxide Ultrafiltration Membranes from Solutions in Ionic Liquid

KAUST Repository

Mahalingam, Dinesh. K.

2017-07-18

Novel high flux polyethersulfone (PES) ultrafiltration membranes were fabricated by incorporating different amounts of graphene oxide (GO) sheets to PES as nanofillers. The membranes were prepared from solutions in 50/50 1-ethyl-3-methylimidazolium-diethylphosphate/N,N-dimethyl formamide. It was observed that the water permeance increased from 550 to 800 L m-2h-1bar-1, with incorporation of 1 wt% GO, keeping a molecular weight cut-off (MWCO) of approximately 32-34 kg mol-1. Cross-sectional scanning electron microscopy images of GO/PES membranes showed the formation of ultrathin selective layer unlike pristine membranes. Contact angle measurements confirmed the increase of hydrophilicity, by increasing the GO concentration. The rejection of humic acid and bovine serum albumin was demonstrated. The mechanical properties were improved, compared with the pristine membranes. The performance was just above the trade-off relationship between permeance and separation factor for PES membranes reported in the literature.

Development of high performance nano-porous polyethersulfone ultrafiltration membranes with hydrophilic surface and superior antifouling properties

International Nuclear Information System (INIS)

Rahimpour, Ahmad; Madaeni, Sayed Siavash; Jahanshahi, Mohsen; Mansourpanah, Yaghoub; Mortazavian, Narmin

2009-01-01

Hydrophilic nano-porous polyethersulfone ultrafiltration membranes were developed for milk concentration. The membranes were prepared from new dope solution containing polyethersulfone (PES)/polyvinylpirrolidone (PVP)/polyethyleneglycole (PEG)/cellulose acetate phthalate (CAP)/acrylic acid/Triton X-100 using phase inversion induced by immersion precipitation technique. This casting solution leads to formation of new hydrophilic membranes. The morphological studies were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). In addition, the hydrophilicity and performance of membranes were examined by contact angel measurements and cross-flow filtration (pure water flux, milk water permeation, protein rejection and antifouling measurements). The contact angle measurements indicate that a surface with superior hydrophilicity was obtained for PES membranes. Two concentrations of PES (16 and 14.4 wt.%) and two different non-solvents (pure water and mixtures of water and IPA) were used for preparation of membranes. The morphological studies showed that the higher concentration of PES and the presence of IPA in the gelation media results in formation of a membrane with a dense top and sub-layer with small pores on the surface. The pure water flux of membranes was decreased when higher polymer concentration and mixtures of water and IPA were employed for membrane formation. On the other hand, the milk water permeation and protein rejection were increased using mixtures of water and IPA as non-solvent. Furthermore, the fouling analysis of the membranes demonstrated that the membrane surface with fewer tendencies for fouling was obtained.

Polyethersulfone/clay membranes and its water permeability; Membranas de polietersulfona/argila e sua permeabilidade a agua

Energy Technology Data Exchange (ETDEWEB)

Cavalho, Thamyres Cardoso de; Medeiros, Vanessa da Nobrega; Araujo, Edcleide Maria de; Lira, Helio Lucena, E-mail: thamyrescc@gmail.com, E-mail: vanismedeiros@gmail.com, E-mail: edcleide.araujo@ufcg.edu.br, E-mail: helio.lira@ufcg.edu.br [Universidade Federal de Campina Grande (UAEMa/CCT/UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais; Leite, Amanda Melissa Damiao, E-mail: amanda.leite@ect.ufrn.br [Universidade Federal do Rio Grande do Norte (ECT/UFRN), Natal, RN (Brazil). Escola de Ciencia e Tecnologia

2017-04-15

Membranes can be considered polymeric or inorganic films that function as a semipermeable barrier to filtration on a molecular scale, separating two phases and restricting, totally or partially, the transportation of one or more chemical species (solute) present in the solution. Therefore, the aim of this work is to produce polyethersulfone membranes (PES) and polyethersulfone/clay by phase inversion technique and evaluate the presence of clay in obtaining membranes for wastewater treatment. The used solvent was dimethylformamide (DMF) and clays were Brasgel PA (MMT) and Cloisite Na (CL Na) in the proportion of 3 to 5% (wt.). By Xray diffraction (XRD), the membranes with 3% of MMT and CL Na clays apparently had partially exfoliated structures. For the composition with 5% of CL Na a small peak was observed, which indicates that this is possibly an intercalated structure or microcomposite. By scanning electron microscopy (SEM), visualizes that the pure surface of the pure PES membrane a structure apparently without pores was observed in the used magnification and without roughness surface when compared to membranes with clay. The measurements of contact angle indicated that the inclusion of clay altered the wetting ability of the membranes. The flow with distilled water for all membranes started high and over time reached a stabilization level. Thus, it can be concluded that the presence and the content of clay altered the morphology of the membrane, contributing to an increase in water flow. (author)

A Comparison on Gas Separation between PES(polyethersulfone)/MMT (Na-montmorillonite) and PES/TiO2 Mixed Matrix Membranes

Czech Academy of Sciences Publication Activity Database

Liang, Ch.-Y.; Uchytil, Petr; Petričkovič, Roman; Lai, Y.-Ch.; Friess, K.; Šípek, M.; Reddy, M.M.; Suen, S.-Y.

2012-01-01

Roč. 92, MAY 18 (2012), s. 57-63 ISSN 1383-5866 R&D Projects: GA ČR GCP106/10/J038 Grant - others:NSCT(TW) NSC:99-2911-I-005-002; NSCT(TW) NSC:99-2923-E-005-001-MY2 Institutional research plan: CEZ:AV0Z40720504 Keywords : mixed matrix membrane * polyethersulfone membrane * sodium montmorillonite Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 2.894, year: 2012

Colour-Value Based Method for Polydopamine Coating-Stability Characterization on Polyethersulfone Membranes.

Science.gov (United States)

Bucher, Thomas; Clodt, Juliana I; Grabowski, Andrej; Hein, Martin; Filiz, Volkan

2017-12-16

Porous polyethersulfone membranes as used in oenology were investigated in order to evaluate temperature-dependent permeances in a temperature range from 10 to 35 °C. A temperature correction factor was determined for this type of membrane to get accurate and comparable results for further developments. Moreover, the membranes were modified with a bio-inspired polydopamine coating in order to reduce fouling. The performance of the membranes could be increased with respect to permeance and flux recovery under cross-flow conditions. In order to test the applicability and stability of the coating layer, they were treated with basic and acidic cleaning agents as used in industry for fouled membranes. The chemical stability of the coating layer was studied under basic and acidic conditions, by systematic observation of the colour change of the coated membranes over treatment time.

Hydrophilicity improvement of polyethersulfone powders by grafting acrylic acid with γ-ray simultaneous irradiation method

International Nuclear Information System (INIS)

Deng Bo; Hou Zhengchi; Zhang Fengying; Xie Leidong; Li Jing; Yang Haijun

2005-01-01

Acrylic acid was grafted to Polyethersulfone (PES) powders by liquid-phase simultaneous irradiation. Effects of grafting conditions, such as absorbed dose, volume fraction of monomer, inhibitor (Cu 2+ ) concentration, and pH of the grafting solution on degree of the grafting were investigated. Combined with gravimetric analysis, a working curve of grafting degree through FT-IR quantitative analysis was obtained. The highest grafting degree was achieved at dose of 25 kGy, volume fraction of monomer of 30% and inhibitor concentration of 0.004 mol/L. Greater degrees of the grafting could be obtained by adding increasing amount of hydrochloric acid to the system. Hydrophilicity of the grafted PES powders increased with higher degrees of the grafting. (authors)

Polyethersulfone flat sheet and hollow fiber membranes from solutions in ionic liquids

KAUST Repository

Kim, Dooli

2017-06-10

We fabricated flat-sheet and hollow fiber membranes from polyethersulfone (PES) solutions in two ionic liquids: 1-ethyl-3-methylimidazolium diethyl phosphate ([EMIM]DEP) and 1,3-dimethylimidazolium dimethyl phosphate ([MMIM]DMP). The solvents are non-volatile and less toxic than organic solvents, such as dimethylformamide (DMF). The membranes morphologies were compared with those of membranes prepared from solutions in DMF, using electron microscopy. Water permeance, solute rejection and mechanical strengths were evaluated. Membranes were applied to DNA separation. While membranes based on PES were successfully prepared, polysulfone (PSf) does not dissolve in the same ionic liquids. The discrepancy between PES and PSf could not be explained using classical Flory-Huggins theory, which does not consider the coulombic contributions in ionic liquids. The differences in solubility could be understood, by applying density functional theory to estimate the interaction energy between the different polymers and solvents. The theoretical results were supported by experimental measurements of intrinsic viscosity and dynamic light scattering (DLS).

Microfiltration membranes prepared from polyethersulfone powder grafted with acrylic acid by simultaneous irradiation and their pH dependence

International Nuclear Information System (INIS)

Deng Bo; Li Jingye; Hou Zhengchi; Yao Side; Shi Liuqing; Liang Guoming; Sheng Kanglong

2008-01-01

Polyethersulfone (PES) powder was grafted with acrylic acid (AAc) by simultaneous γ-ray irradiation. The kinetics of the radiation induced graft polymerization was studied and the grafted PES powder was characterized. Then, microfiltration (MF) membranes were prepared from PES-g-PAAc powder with different degrees of grafting (DG) under phase inversion method. The swelling behavior and the mean pore size of MF membranes were measured, and the filtration property was tested. The results showed that the pore size and the flux of MF membranes increased with the increase in DG. And, MF membranes' properties were dependent on the pH value

FABRICATION AND CHARACTERIZATION OF POLYIMIDE/POLYETHERSULFONE-FUMED SILICA MIXED MATRIX MEMBRANE FOR GAS SEPARATION

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A. F. Ismail

2012-01-01

Full Text Available This study is performed primarily to investigate the feasibility of fumed silica as inorganic material towards gas separation performance of mixed matrix membrane. In this study, polyimide/polyethersulfone (PES-fumed silica mixed matrix membranes were casted using dry/wet technique. The results from the FESEM, DSC and FTIR analysis confirmed that the structure and physical properties of membrane is influenced by inorganic filler. FESEM’s cross-section view indicated good compatibility between polymer and fumed silica for all of range fumed silica used in this study. The gas separation performance of the mixed matrix membranes with fumed silica were relatively higher compared to that of the neat PI/PES membrane. PI/PES-fumed silica 5 wt% yielded significant selectivity enhancement of 7.21 and 40.47 for O2/N2, and CO2/CH4, respectively.

Effect of Graphene Oxide (GO) on the Surface Morphology & Hydrophilicity of Polyethersulfone (PES)

Science.gov (United States)

Junaidi, N. F. D.; Khalil, N. A.; Jahari, A. F.; Shaari, N. Z. K.; Shahruddin, M. Z.; Alias, N. H.; Othman, N. H.

2018-05-01

Membrane has been widely used in water and wastewater treatment. One of the major issues related membrane separation is concentration polarization or fouling, which can lead to a decline of flux and premature failure of membrane. However, fouling can be controlled by modification of membrane properties such as morphology and hydrophilicity. In this work, a modification of polymeric membrane, polyethersulfone (PES) was carried out using graphene oxide in order to attain high antifouling characteristics. Graphene oxide (GO) was added at different compositions ranging from (0.1 wt%-1.0 wt%). GO was synthesized using modified Hummers’ method and characterized using XRD and FTIR prior to using it as additive for the PES membrane. The prepared PES-GO composite membranes were characterized using FTIR and SEM, Contact angle measurement and pure water flux test were then conducted to investigate the hydrophilicity of the PES-GO membranes. It was found that the additions of GO has significantly improved the hydrophilicity of the membranes.

Polyethersulfone-based ultrafiltration hollow fibre membrane for drinking water treatment systems

Science.gov (United States)

Chew, Chun Ming; Ng, K. M. David; Ooi, H. H. Richard

2017-12-01

Conventional media/sand filtration has been the mainstream water treatment process for most municipal water treatment plants in Malaysia. Filtrate qualities of conventional media/sand filtration are very much dependent on the coagulation-flocculation process prior to filtration and might be as high as 5 NTU. However, the demands for better quality of drinking water through public piped-water supply systems are growing. Polymeric ultrafiltration (UF) hollow fibre membrane made from modified polyethersulfone (PES) material is highly hydrophilic with high tensile strength and produces excellent quality filtrate of below 0.3 NTU in turbidity. This advanced membrane filtration material is also chemical resistance which allows a typical lifespan of 5 years. Comparisons between the conventional media/sand filtration and PES-based UF systems are carried out in this paper. UF has been considered as the emerging technology in municipal drinking water treatment plants due to its consistency in producing high quality filtrates even without the coagulation-flocculation process. The decreasing cost of PES-based membrane due to mass production and competitive pricing by manufacturers has made the UF technology affordable for industrial-scale water treatment plants.

Selective extraction of plutonium from nitric acid medium by bifunctional polyethersulfone beads for quantification with thermal ionisation mass spectrometry

International Nuclear Information System (INIS)

Paul, Sumana; Aggarwal, S.K.; Pandey, A.K.

2015-01-01

Polyethersulfone (PES) magnetic beads were prepared by phase inversion technique. The beads were grafted with two monomers, viz. 2-hydroxyethylmethacrylate phosphoric acid (HEMP) and (3-acrylamidopropyl)trimethyl ammonium chloride (AMAC), by photo-induced free radical polymerization. Effect of different HNO 3 concentrations on the sorption profiles of Am(III) and Pu(IV) was studied using the grafted PES beads. The beads were found to extract plutonium quantitatively from high nitric acid medium (3-8 M). The effect of presence of competing actinide, e.g. U(VI), on the sorption of Pu(IV) was also studied. (author)

Development and characterization of polyethersulfone/TiO2 mixed matrix membranes for CO2/CH4 separation

Science.gov (United States)

Galaleldin, S.; Mannan, H. A.; Mukhtar, H.

2017-12-01

In this study, mixed matrix membranes comprised of polyethersulfone as the bulk polymer phase and titanium dioxide (TiO2) nanoparticles as the inorganic discontinuous phase were prepared for CO2/CH4 separation. Membranes were synthesized at filler loading of 0, 5, 10 and 15 wt % via dry phase inversion method. Morphology, chemical bonding and thermal characteristics of membranes were scrutinized utilizing different techniques, namely: Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform InfraRed (FTIR) spectra and Thermogravimetric analysis (TGA) respectively. Membranes gas separation performance was evaluated for CO2 and CH4 gases at 4 bar feed pressure. The highest separation performance was achieved by mixed matrix membrane (MMM) at 5 % loading of TiO2.

Corona-induced graft polymerization for surface modification of porous polyethersulfone membranes

International Nuclear Information System (INIS)

Zhu Liping; Zhu Baoku; Xu Li; Feng Yongxiang; Liu Fu; Xu Youyi

2007-01-01

Graft polymerization of acrylic acid (AA) onto porous polyethersulfone (PES) membrane surfaces was developed using corona discharge in atmospheric ambience as an activation process followed by polymerization of AA in aqueous solution. The effects of the corona parameters and graft polymerization conditions on grafting yield (GY) of AA were investigated. The grafting of AA on the PES membranes was confirmed by ATR-FTIR and X-ray photoelectron spectroscopy (XPS) analysis. Porosimetry measurements indicate the average pore diameters and porosities of the modified membranes decrease with the increase of the GY. The hydrophilicity and surface wetting properties of the original and modified membranes were evaluated by observing the dynamic changes of water contact angles. It is found that the grafting of AA occurs not only on the membrane surfaces, but also on the pore walls of the cells inside the membrane. The permeability experiments of protein solution reveal that the grafting of PAA endows the modified membranes with enhanced fluxes and anti-fouling properties. The optimized GY of AA is in the range of 150-200 μg/cm 2 . In addition, the tensile experiments show the corona discharge treatment with the power lower than 150 W yields little damage to the mechanical strength of the membranes

Modification of polyethersulfone films by grafting hydrophilic monomers with 60Co γ-rays

International Nuclear Information System (INIS)

Hou Zhengchi; Deng Bo; Li Jing

2006-01-01

Polyethersulfone (PES), with its high strength, high temperature resistance, corrosion- resistance, oxidation resistance and applicability under wide pH range, is used extensively as ultrafiltration and nanofiltration membrane. However, PES membranes foul easily in such an application because of hydrophobic nature of PES raw materials. Improving the hydrophilicity of PES by grafting hydrophilic monomers onto it is of potential to solve the problem. At present, common approaches to improve hydrophilicity of PES membranes are UV grafting modification, plasma modification, and chemical modification, whereas grafting and modifying PES films by 60 Co γ-rays has rarely been reported. Studies have been carried out in our laboratory to graft hydrophilic monomers onto PES membranes directly or PES powders via simultaneous radiation grafting with the rays. Acrylic acid, methyl acrylic acid or acrylamide was used to study effects of the monomer concentration, irradiation dose and dose rate, solvent, inhibitor and pH of the grafting solution on the degree of grafting. The results showed that hydrophilicity of all the PES membranes could be improved, with the extent of improvement being dependent on the grafting conditions. (authors)

KrF laser ablation of a polyethersulfone film: Effect of pulse duration on structure formation

International Nuclear Information System (INIS)

Pazokian, Hedieh; Selimis, Alexandros; Stratakis, Emmanuel; Mollabashi, Mahmoud; Barzin, Jalal; Jelvani, Saeid

2011-01-01

Polyethersulfone (PES) films were processed with KrF laser irradiation of different pulse durations (τ). Scanning electron microscopy (SEM) and Raman spectroscopy were employed for the examination of the morphology and chemical composition of the irradiated surfaces, respectively. During ablation with 500 fs and 5 ps pulses, localized deformations (beads), micro-ripple and conical structures were observed on the surface depending on the irradiation fluence (F) and the number of pulses (N). In addition, the number density of the structures is affected by the irradiation parameters (τ, F, N). Furthermore, at longer pulse durations (τ = 30 ns), conical structures appear at lower laser fluence values, which are converted into columnar structures upon irradiation at higher fluences. The Raman spectra collected from the top of the structures following irradiation at different pulse durations revealed graphitization of the ns laser treated areas, in contrast to those processed with ultra-short laser pulses.

Estudio de la resistencia a la abrasión de capas vitrocerámicas depositadas sobre acero

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Gómez de Salazar, J. M.

2002-12-01

Full Text Available Wear test has been completed on two types of layered materials: a non-reinforced enamel plate and a ceramic reinforced enamel plate. The latter has been tested in two forms: with 10 wt. % and 20 wt. % ceramic particles reinforcement. For comparison the same test has also been completed on polished steel. Wear resistance was measure using a tribometer, equipped with a chromium steel sphere of 6 mm diameter. The sphere-plate surface contact area increases with distance covered, which in the polished steel provokes exponential increments in wear values. This exponential behaviour was not observed in the enamel plates due to their greater wear resistance. The reinforcement of the enamel plates with ceramic particles increases the wear resistance. A higher percentage of ceramic reinforcement results in a greater wear resistance of the plates.

Se han realizado ensayos de desgaste, tanto en placas esmaltadas sin refuerzo como en esmaltes con distinto porcentaje de carga cerámica (10 y 20% en peso, y se han comparado frente al del acero base pulido. Las medidas de resistencia a la abrasión se han obtenido utilizado un tribómetro con bola de acero al cromo de 6 mm de diámetro. El aumento de la superficie de contacto bola-placa a medida que aumenta la distancia recorrida, provoca aumentos exponenciales en los desgastes en el caso del acero pulido. Sin embargo, en el caso de las chapas esmaltadas no se observa este comportamiento, debido a la mayor resistencia al desgaste de las mismas. Cuando las capas esmaltadas están reforzadas con cargas cerámicas, la resistencia al desgaste aumenta con el porcentaje de refuerzo cerámico.

Ensayo sobre endurecimiento de adhesivos estructurales sometidos a cargas dinámicas

Directory of Open Access Journals (Sweden)

Recuero, A.

2004-04-01

Full Text Available Carbon fibre reinforced polymers are increasingly replacing the steel reinforcing systems in the repair and strengthening of concrete structures thanks to their high strength/weight and stiffness/weight ratios, corrosion resistance, lightweight, and ease of handling and application. This paper presents a study on the behaviour of bridge concrete beams strengthened with CFRP sheets when the strengthening is made when traffic is acting so that the structure is subjected to dynamic loads while the adhesive is still fresh. No reduction in the effectiveness of the strengthening was observed in the tests.

Los polímeros reforzados con fibras de carbono se están utilizando cada vez más para el refuerzo de estructuras de hormigón, reemplazando a los sistemas tradicionales de refuerzo con acero. Esto es debido a sus altas resistencia y rigidez específicas, resistencia a la corrosión, ligereza y facilidad de manejo y puesta en obra. Este artículo presenta un estudio sobre el comportamiento de vigas de puentes reforzadas con bandas de CFRP mientras se mantiene el puente en servicio de manera que la estructura está sometida a cargas dinámicas con el adhesivo fresco. En los ensayos realizados se ha observado que las cargas dinámicas no afectan a la efectividad del refuerzo.

Preparation of polyethersulfone-organophilic montmorillonite hybrid particles for the removal of bisphenol A

International Nuclear Information System (INIS)

Cao Fuming; Bai Pengli; Li Haocheng; Ma Yunli; Deng Xiaopei; Zhao Changsheng

2009-01-01

Polyethersulfone (PES)-organophilic montmorillonite (OMMT) hybrid particles, with various proportions of OMMT, were prepared by using a liquid-liquid phase separation technique, and then were used for the removal of bisphenol A (BPA) from aqueous solution. The adsorbed BPA amounts increased significantly when the OMMT were embedded into the particles. The structure of the particle was characterized by using scanning electron microscopy (SEM); and these particles hardly release small molecules below 250 deg. C which was testified by using thermogravimetric analysis (TGA). The experimental data of BPA adsorption were adequately fitted with Langmuir equations. Three simplified kinetics model including the pseudo-first-order (Lagergren equation), the pseudo-second-order, and the intraparticle diffusion model were used to describe the adsorption process. Kinetic studies showed that the adsorbed BPA amount reached an equilibrium value after 300 min, and the experimental data could be expressed by the intraparticular mass transfer diffusion model. Furthermore, the adsorbed BPA could be effectively removed by ethanol, which indicated that the hybrid particles could be reused. These results showed that the PES-OMMT hybrid particles have the potential to be used in the environmental application

Antithrombogenicity of Fluorinated Diamond-Like Carbon Films Coated Nano Porous Polyethersulfone (PES) Membrane

Science.gov (United States)

Prihandana, Gunawan S.; Sanada, Ippei; Ito, Hikaru; Noborisaka, Mayui; Kanno, Yoshihiko; Suzuki, Tetsuya; Miki, Norihisa

2013-01-01

A nano porous polyethersulfone (PES) membrane is widely used for aspects of nanofiltration, such as purification, fractionation and dialysis. However, the low-blood-compatibility characteristic of PES membrane causes platelets and blood cells to stick to the surface of the membrane and degrades ions diffusion through membrane, which further limits its application for dialysis systems. In this study, we deposited the fluorinated-diamond-like-carbon (F-DLC) onto the finger like structure layer of the PES membrane. By doing this, we have the F-DLC films coating the membrane surface without sacrificing the membrane permeability. In addition, we examined antithrombogenicity of the F-DLC/PES membranes using a microfluidic device, and experimentally found that F-DLC drastically reduced the amount of blood cells attached to the surface. We have also conducted long-term experiments for 24 days and the diffusion characteristics were found to be deteriorated due to fouling without any surface modification. On the other hand, the membranes coated by F-DLC film gave a consistent diffusion coefficient of ions transfer through a membrane porous. Therefore, F-DLC films can be a great candidate to improve the antithrombogenic characteristics of the membrane surfaces in hemodialysis systems. PMID:28788333

ArF laser surface modification of polyethersulfone film: Effect of laser fluence in improving surface biocompatibility

International Nuclear Information System (INIS)

Pazokian, H.; Jelvani, S.; Mollabashi, M.; Barzin, J.; Azizabadi Farahani, G.

2011-01-01

ArF laser treatment of polyethersulfone (PES) films was performed to improve biocompatibility of surfaces. For this purpose, the threshold fluence for laser ablation of PES was obtained from experimental measurements and then samples were irradiated at 2 separate ranges of fluences, i.e. below and above the ablation threshold. In order to investigate the physico-chemical changes, the modified surfaces were characterized by attenuated total reflectance (ATR) infrared spectroscopy and contact-angle measurements. The biocompatibility of the treated samples in comparison to those untreated was examined in vitro using a platelet adhesion test. The number of adhered platelets was obtained using the lactate dehydrogenase (LDH) method. For surfaces irradiated below the ablation threshold, a high reduction in the number of the adhered platelets was observed; while this number increased in samples treated at the fluence above the ablation threshold. The change in platelet adhesion was attributed to the change in chemistry and roughness of the irradiated surfaces.

Mussel-inspired chitosan-polyurethane coatings for improving the antifouling and antibacterial properties of polyethersulfone membranes.

Science.gov (United States)

Wang, Rui; Song, Xin; Xiang, Tao; Liu, Qiang; Su, Baihai; Zhao, Weifeng; Zhao, Changsheng

2017-07-15

A straightforward mussel-inspired approach was proposed to construct chitosan-polyurethane coatings and load Ag nanoparticles (AgNPs) to endow polyethersulfone (PES) membranes with dual-antibacterial and antifouling properties. The macromolecule O-carboxymethyl chitosan (CMC) was directly reacted with catechol in the absence of carbodiimide chemistry to form the coating and load AgNPs via in situ reduction; while lysine (Lys) was used as a representative small molecule for comparison. Then, PEG-based polyurethane (PU) was used for constructing Lys-Ag-PU and CMC-Ag-PU composite coatings, which substantially improved the protein antifouling property of the membranes. Furthermore, the CMC-Ag-PU coating exhibited superior broad-spectrum antibacterial property towards E. coli and S. aureus than Lys-Ag-PU coating. Meanwhile, the CMC-Ag-PU coating showed sustained antifouling property against bacteria and could reload AgNPs to be regenerated as antibacterial and antifouling coating. This approach is believed to have potential to fabricate reusable antifouling and antibacterial coatings on materials surfaces for aquatic industries. Copyright © 2017 Elsevier Ltd. All rights reserved.

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.

Fouling Characteristics of Dissolved Organic Matter in Papermaking Process Water on Polyethersulfone Ultrafiltration Membranes

Directory of Open Access Journals (Sweden)

Wenpeng Su

2015-07-01

Full Text Available In the papermaking industry, closure of process water (whitewater circuits has been used to reduce fresh water consumption. Membrane separation technology has potential for use in treating process water for recirculation. The purpose of this study was to reveal the fouling characteristics of a polyethersulfone (PES ultrafiltration membrane caused by dissolved organic matter (DOM in process water. Ultrafiltration membranes (UF and DAX ion exchange resins were applied to characterize the molecular weight (MW and hydrophilicity distribution of DOM. The interactions between various fractions of DOM and a PES ultrafiltration membrane were investigated. The membrane fouling characteristics were elucidated by examining the filtration resistances and linearized Herman’s blocking models. The results demonstrated that the membrane was fouled significantly by much of the MW distribution. The membrane was fouled more significantly by the low MW fraction rather than the high MW fraction. The filtration resistances and the fitted equation of Hermia’s laws indicated that hydrophilic organics were the main foulants. The hydrophilic organics partially block the membrane pores and form intermediate blocking, reducing the effective filtration area, while the hydrophobic organics form a gel layer or cake on the surface of the membrane.

Antithrombogenicity of Fluorinated Diamond-Like Carbon Films Coated Nano Porous Polyethersulfone (PES Membrane

Directory of Open Access Journals (Sweden)

Norihisa Miki

2013-09-01

Full Text Available A nano porous polyethersulfone (PES membrane is widely used for aspects of nanofiltration, such as purification, fractionation and dialysis. However, the low-blood-compatibility characteristic of PES membrane causes platelets and blood cells to stick to the surface of the membrane and degrades ions diffusion through membrane, which further limits its application for dialysis systems. In this study, we deposited the fluorinated-diamond-like-carbon (F-DLC onto the finger like structure layer of the PES membrane. By doing this, we have the F-DLC films coating the membrane surface without sacrificing the membrane permeability. In addition, we examined antithrombogenicity of the F-DLC/PES membranes using a microfluidic device, and experimentally found that F-DLC drastically reduced the amount of blood cells attached to the surface. We have also conducted long-term experiments for 24 days and the diffusion characteristics were found to be deteriorated due to fouling without any surface modification. On the other hand, the membranes coated by F-DLC film gave a consistent diffusion coefficient of ions transfer through a membrane porous. Therefore, F-DLC films can be a great candidate to improve the antithrombogenic characteristics of the membrane surfaces in hemodialysis systems.

Thickness Dependence of Optoelectrical Properties of Mo-Doped In2O3 Films Deposited on Polyethersulfone Substrates by Ion-Beam-Assisted Evaporation

Directory of Open Access Journals (Sweden)

Chin-Chiuan Kuo

2010-01-01

Full Text Available Indium molybdenum oxide (IMO films were deposited onto the polyethersulfone (PES substrates by ion-beam-assisted evaporation (IBAE deposition at low temperature in this study. The effects of film thickness on their optical and electrical properties were investigated. The results show that the deposited IMO films exhibit a preferred orientation of B(222. The electrical resistivity of the deposited film initially reduces then subsequently increases with film thickness. The IMO film with the lowest resistivity of 7.61 × 10−4 ohm-cm has been achieved when the film thickness is 120 nm. It exhibits a satisfactory surface roughness pv of 8.75 nm and an average visible transmittance of 78.7%.

Aluminum oxide barrier coating on polyethersulfone substrate by atomic layer deposition for barrier property enhancement

International Nuclear Information System (INIS)

Kim, Hyun Gi; Kim, Sung Soo

2011-01-01

Aluminum oxide layers were deposited on flexible polyethersulfone (PES) substrates via plasma enhanced atomic layer deposition (PEALD) process using trimethylaluminum (TMA) and oxygen as precursor and reactant materials. Several process parameters in PEALD process were investigated in terms of refractive index and layer thickness. Number of process cycle increased the thickness and refractive index of the layer to enhance the barrier properties. Non-physisorbed TMA and unreacted oxygen were purged before and after the plasma reaction, respectively. Identical purge time was applied to TMA and oxygen and it was optimized for 10 s. Thinner and denser layer was formed as substrate temperature increased. However, the PES substrate could be deformed above 120 o C. Aluminum oxide layer formed on PES at optimized conditions have 11.8 nm of thickness and reduced water vapor transmission rate and oxygen transmission rate to below 4 x 10 -3 g/m 2 day and 4 x 10 -3 cm 3 /m 2 day, respectively. Polycarbonate and polyethylene naphthalate films were also tested at optimized conditions, and they also showed quite appreciable barrier properties to be used as plastic substrates.

Plasma treatment of polyethersulfone membrane for benzene removal from water by air gap membrane distillation.

Science.gov (United States)

Pedram, Sara; Mortaheb, Hamid Reza; Arefi-Khonsari, Farzaneh

2018-01-01

In order to obtain a durable cost-effective membrane for membrane distillation (MD) process, flat sheet polyethersulfone (PES) membranes were modified by an atmospheric pressure nonequilibrium plasma generated using a dielectric barrier discharge in a mixture of argon and hexamethyldisiloxane as the organosilicon precursor. The surface properties of the plasma-modified membranes were characterized by water contact angle (CA), liquid entry pressure, X-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy. The water CA of the membrane was increased from 64° to 104° by depositing a Si(CH 3 )-rich thin layer. While the pristine PES membrane was not applicable in the MD process, the modified PES membrane could be applied for the first time in an air gap membrane distillation setup for the removal of benzene as a volatile organic compound from water. The experimental design using central composite design and response surface methodology was applied to study the effects of feed temperature, concentration, and flow rate as well as their binary interactions on the overall permeate flux and separation factor. The separation factor and permeation flux of the modified PES membrane at optimum conditions were comparable with those of commercial polytetrafluoroethylene membrane.

Facile fabrication of ultrathin hybrid membrane for highly flexible supercapacitors via in-situ phase separation of polyethersulfone

Science.gov (United States)

Zhao, Xiaoning; Ran, Fen; Shen, Kuiwen; Yang, Yunlong; Wu, Jiayu; Niu, Xiaoqin; Kong, Lingbin; Kang, Long; Chen, Shaowei

2016-10-01

In this article, a facile method based on in-situ phase-separation was developed for the fabrication of ultrathin hybrid membranes for highly flexible supercapacitors. The structures and morphologies of the prepared electrodes were characterized by scanning electron microscopy (SEM), Fourier-transformed infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) measurements; and the electrochemical behaviors were examined in 2 M KOH solution. SEM and FTIR characterizations reveal that activated carbon was imbedded into the polymer membrane of polyethersulfone to form a uniform and flexible hybrid membrane. When the thin polymer-carbon membrane (PCM) was used as an electrode material for supercapacitor, a high specific capacitance of 169.4 Fg-1 was obtained at a current density of 0.5 Ag-1 along with good long-term cycle life of 94.6% capacity retention after 2000 charging-discharging cycles. Benefiting from these merits, the as-fabricated PCM//PCM cell shows an excellent electrochemical property. These results suggest a promising route towards the fabrication of highly flexible electrodes for high-performance supercapacitors.

Behavior of reinforced concrete beams reinforced with GFRP bars

Directory of Open Access Journals (Sweden)

D. H. Tavares

Full Text Available The use of fiber reinforced polymer (FRP bars is one of the alternatives presented in recent studies to prevent the drawbacks related to the steel reinforcement in specific reinforced concrete members. In this work, six reinforced concrete beams were submitted to four point bending tests. One beam was reinforced with CA-50 steel bars and five with glass fiber reinforced polymer (GFRP bars. The tests were carried out in the Department of Structural Engineering in São Carlos Engineering School, São Paulo University. The objective of the test program was to compare strength, reinforcement deformation, displacement, and some anchorage aspects between the GFRP-reinforced concrete beams and the steel-reinforced concrete beam. The results show that, even though four GFRP-reinforced concrete beams were designed with the same internal tension force as that with steel reinforcement, their capacity was lower than that of the steel-reinforced beam. The results also show that similar flexural capacity can be achieved for the steel- and for the GFRP-reinforced concrete beams by controlling the stiffness (reinforcement modulus of elasticity multiplied by the bar cross-sectional area - EA and the tension force of the GFRP bars.

Graphene immobilized enzyme/polyethersulfone mixed matrix membrane: Enhanced antibacterial, permeable and mechanical properties

International Nuclear Information System (INIS)

Duan, Linlin; Wang, Yuanming; Zhang, Yatao; Liu, Jindun

2015-01-01

Graphical abstract: - Highlights: • Lysozyme was immobilized on the surface of graphene oxide (GO) and reduced GO (RGO). • The novel hybrid membranes based on lysozyme and graphene were fabricated firstly. • These membranes showed good antibacterial and mechanical performance. - Abstract: Enzyme immobilization has been developed to address lots of issues of free enzyme, such as instability, low activity and difficult to retain. In this study, graphene was used as an ideal carrier for lysozyme immobilization, including graphene oxide (GO) immobilized lysozyme (GO-Ly) and chemically reduced graphene oxide (CRGO) immobilized lysozyme (CRGO-Ly). Herein, lysozyme as a bio-antibacterial agent has excellent antibacterial performance and the products of its catalysis are safety and nontoxic. Then the immobilized lysozyme materials were blended into polyethersulfone (PES) casting solution to prepare PES ultrafiltration membrane via phase inversion method. GO and CRGO were characterized by Fourier transform infrared spectroscopy (FTIR), Ultraviolet–visible spectrum (UV), X-ray diffraction (XRD), and transmission electron microscopy (TEM) and the immobilized lysozyme composites were observed by fluorescent microscopy. The results revealed that GO and CRGO were successfully synthesized and lysozyme was immobilized on their surfaces. The morphology, hydrophilicity, mechanical properties, separation properties and antibacterial activity of the hybrid membranes were characterized in detail. The hydrophilicity, water flux and mechanical strength of the hybrid membranes were significantly enhanced after adding the immobilized lysozyme. In the antibacterial experiment, the hybrid membranes exhibited an effective antibacterial performance against Escherichia coli (E. coli).

Structural and optical properties of ZnO nanostructures electrochemically synthesized on AZO/Ag/AZO-multilayer-film-coated polyethersulfone substrates

International Nuclear Information System (INIS)

Oh, Dohyun; Yoo, Chanho; No, Youngsoo; Kim, Suyoun; Kim, Taewhan; Cho, Woonjo; Kim, Jinyoung

2012-01-01

ZnO nanostructures were formed on Al-doped ZnO (AZO)/Ag/AZO-multilayer-film-coated flexible polyethersulfone (PES) substrates at low temperature by using an electrochemical deposition method. The resistivity of the AZO/Ag/AZO multilayer films decreased with increasing thickness of the Ag film. X-ray diffraction patterns for the ZnO nanostructures showed that the crystal structure of the ZnO was hexagonal wurtzite and that the orientation was along the c-axis perpendicular to the substrate. Scanning electron microscopy images showed that the ZnO nanostructures grown at current densities of - 1.0 and - 1.5 mA/cm 2 were ZnO nanorods with diameters of 150 nm and ZnO nanoflowers with a planar dimension, respectively. Photoluminescence spectra showed that the band-edge emission peak of the ZnO nanostructures dominantly appeared in the ultraviolet region. These results showed that ZnO nanorods and nanoflowers with high quality were synthesized on AZO/Ag/AZO-multilayer-film-coated PES substrates.

Surface and anti-fouling properties of a polyampholyte hydrogel grafted onto a polyethersulfone membrane.

Science.gov (United States)

Zhang, Wei; Yang, Zhe; Kaufman, Yair; Bernstein, Roy

2018-05-01

Zwitterion polymers have anti-fouling properties; therefore, grafting new zwitterions to surfaces, particularly as hydrogels, is one of the leading research directions for preventing fouling. Specifically, polyampholytes, polymers of random mixed charged subunits with a net-electric charge, offer a synthetically easy alternative for studying new zwitterions with a broad spectrum of charged moieties. Here, a novel polyampholyte hydrogel was grafted onto the surface of polyethersulfone membrane by copolymerizing a mixture of vinylsulfonic acid (VSA) and [2-(methacryloyloxy)ethyl]trimethylammonium chloride (METMAC) as the negatively and positively charged monomers, respectively, using various monomer ratios in the polymerization solution, and with N,N'-methylenebisacrylamide as the crosslinker. The physicochemical, morphological and anti-fouling properties of the modified membranes were systematically investigated. Hydrophilic hydrogels were successfully grafted using monomers at different molar ratios. A thin-film zwitterion hydrogel (∼90 nm) was achieved at a 3:1 [VSA:METMAC] molar ratio in the polymerization solution. Among all examined membranes, the zwitterion polyampholyte-modified membrane demonstrated the lowest adsorption of proteins, humic acid, and sodium alginate. It also had low fouling and high flux recovery following filtration with a protein or with an extracellular polymeric substance solution. These findings suggest that this polyampholyte hydrogel is applicable as a low fouling surface coating. Copyright © 2018 Elsevier Inc. All rights reserved.

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

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

Dinámica de la identidad, acción y contexto

Directory of Open Access Journals (Sweden)

Anne Marie Costalat-Founeau

2007-06-01

Full Text Available La identidad social no puede ser considerada más como una imagen fijada y estática que determina las representaciones individuales y/o colectivas. Se inserta, más bien, dentro de una dinámica de representaciones que está marcada por fases biográficas y sociales. Esta impresión social está en parte construida por la experiencia personal impresa en los recuerdos, y transfiere una realidad experiencial a la identidad. La acción participa en esta concretización y también la refuerza: es así que el carácter normativo de la acción parece reforzar su propia manifestación y, por lo tanto, su efecto. Esos efectos tienen un poder central en la dinámica de la identidad. La acción se ubica en el centro de la subjetividad, pues pone en relación las aspiraciones, las representaciones y también los valores y el sentimiento de capacidad: la acción favorece una relación estrecha entre los factores afectivos y cognitivos. Esos factores actúan en conjunto elaborando regulaciones dinámicas y organizando fases de identidad más o menos conflictivas. Se presentan los efectos de la acción sobre la subjetividad.---Social identity should not be considered anymore as a fixed and static image that defines individual or collective representations. It is embedded within a representational dynamic where biographical and social phases left their marks. This social imprint is partly made by the experience ingrained in the remembrance that gives all its experiential reality to identity. Action participates and reinforces this concreteness. It seems that the prescriptive nature of action reinforces its presence and therefore its effects. More precisely, these effects, which are inherent to action, possess a central power in the identity dynamic. Action is at the heart of subjectivity in the sense that it connects aspirations, representations, as well as the values of the individual and the sense of his own capacity. It involves the tight interweaving of

Braided reinforced composite rods for the internal reinforcement of concrete

Science.gov (United States)

Gonilho Pereira, C.; Fangueiro, R.; Jalali, S.; Araujo, M.; Marques, P.

2008-05-01

This paper reports on the development of braided reinforced composite rods as a substitute for the steel reinforcement in concrete. The research work aims at understanding the mechanical behaviour of core-reinforced braided fabrics and braided reinforced composite rods, namely concerning the influence of the braiding angle, the type of core reinforcement fibre, and preloading and postloading conditions. The core-reinforced braided fabrics were made from polyester fibres for producing braided structures, and E-glass, carbon, HT polyethylene, and sisal fibres were used for the core reinforcement. The braided reinforced composite rods were obtained by impregnating the core-reinforced braided fabric with a vinyl ester resin. The preloading of the core-reinforced braided fabrics and the postloading of the braided reinforced composite rods were performed in three and two stages, respectively. The results of tensile tests carried out on different samples of core-reinforced braided fabrics are presented and discussed. The tensile and bending properties of the braided reinforced composite rods have been evaluated, and the results obtained are presented, discussed, and compared with those of conventional materials, such as steel.

Hemocompatible polyethersulfone/polyurethane composite membrane for high-performance antifouling and antithrombotic dialyzer.

Science.gov (United States)

Yin, Zehua; Cheng, Chong; Qin, Hui; Nie, Chuanxiong; He, Chao; Zhao, Changsheng

2015-01-01

Researches on blood purification membranes are fuelled by diverse clinical needs, such as hemodialysis, hemodiafiltration, hemofiltration, plasmapheresis, and plasma collection. To approach high-performance dialyzer, the integrated antifouling and antithrombotic properties are highly necessary for the design/modification of advanced artificial membranes. In this study, we propose and demonstrate that the physical blend of triblock polyurethane (PU) and polyethersulfone (PES) may advance the performance of hemodialysis membranes with greatly enhanced blood compatibility. It was found that the triblock PU could be blended with PES at high ratio owing to their excellent miscibility. The surfaces of the PES/PU composite membranes were characterized using attenuated total reflectance-Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, water contact angle measurement, and surface ζ-potentials. The results indicated that the membrane surfaces were assembled with hydrophilic segregation layer owing to the migration of amphiphilic PU segments during membrane preparation, which might confer the composite membranes with superior hemocompatibility. The cross-section scanning electron microscopy images of the composite membranes exhibited structure transformation from finger-like structure to sponge-like structure, which indicated that the composite membrane had tunable porosity and permeability. The further ultrafiltration experiments indicated that the composite membranes showed increased permeability and excellent antifouling ability. The blood compatibility observation indicated that PES/PU composite membranes owned decreased protein adsorption, suppressed platelet adhesion, and prolonged plasma recalcification time. These results indicated that the PES/PU composite membranes exhibited enhanced antifouling and antithrombotic properties than the pristine PES membrane. The strategy may forward the fabrication of blood compatible composite membranes for

Flexural reinforced concrete member with FRP reinforcement

OpenAIRE

Putzolu, Mariana

2017-01-01

One of the most problematic point in construction is the durability of the concrete especially related to corrosion of the steel reinforcement. Due to this problem the construction sector, introduced the use of Fiber Reinforced Polymer, the main fibers used in construction are Glass, Carbon and Aramid. In this study, the author aim to analyse the flexural behaviour of concrete beams reinforced with FRP. This aim is achieved by the analysis of specimens reinforced with GFRP bars, with theoreti...

Preparation and dielectric properties of Ba0.95Ca0.05Ti0.8Zr0.2O3-polyethersulfone composites

International Nuclear Information System (INIS)

Wang Fajun; Li Wen; Jiang Hongliu; Xue Mingshan; Lu Jinshan; Yao Junping

2010-01-01

We report the preparation and dielectric properties of ceramic-polymer composites using Ba 0.95 Ca 0.05 Ti 0.8 Zr 0.2 O 3 (BCTZ) as a ceramic filler and polyethersulfone (PES) as a polymer matrix. The BCTZ powders were synthesized by a sol-gel method to fabricate BCZT-PES composites. The composites with various BCTZ volume fractions were prepared by a solution mixing and hot-pressing method. The composite with 50 vol % BCTZ showed high dielectric constant (ε=48.80) and low loss (tan δ=0.042) at 1 kHz and room temperature. Such excellent dielectric properties of the composites displayed an acceptable stability within a wide range of temperature (from 20 to 150 deg. C) and frequency (from 100 Hz to 100 kHz). The present work indicates that the BCTZ-PES composite can be a candidate for embedded capacitors.

Structural and optical properties of ZnO rods hydrothermally formed on polyethersulfone substrates

Energy Technology Data Exchange (ETDEWEB)

Shin, Chang Mi; Jang, Jin Tak; Kim, Chang Yong; Ryu, Hyuk Hyun [Inje University, Gimhae (Korea, Republic of); Lee, Won Jae [Dong-Eui University, Busan (Korea, Republic of); Chang, Ji Ho [Korea Maritime University, Busan (Korea, Republic of); Son, Chang Sik [Silla University, Busan (Korea, Republic of); Choi, Hee Lack [Pukyong National University, Busan (Korea, Republic of)

2012-06-15

Various unique ZnO morphologies, such as cigar-like and belt-like structures and microrod and nanorod structures, were formed on flexible polyethersulfone (PES) substrates by using a low temperature hydrothermal route. The structural properties of ZnO depended highly on the precursor concentration. The effect of a thin ZnO seed layer deposited the on PES substrate by using atomic layer deposition on the structural and the optical properties of ZnO hydrothermally grown on the ZnO seed layer/PES substrates was studied. Field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and photoluminescence (PL) measurements were employed to analyze the characteristics of hydrothermally-grown ZnO. The diameter of the ZnO nanorods grown on the ZnO seed layer/PES substrates increased with increasing precursor concentration from 0.025 to 0.125 M due to the Ostwald ripening process. ZnO hydrothermally-grown on the ZnO seed layer/PES substrates at a low precursor concentration showed better structural properties than ZnO formed without a seed layer. Well-formed ZnO nanorods deposited on the ZnO seed layer/PES substrates showed two PL peaks, one in the ultraviolet and the other in the visible region, whereas horizontally positioned ZnO formed on the PES substrate in the absence of a seed layer emitted only one broad PL peak in the violet region. The ZnO grown on PES substrates in this work can be used as high-quality transparent electrodes for solar cells fabricated on flexible substrates.

Structural and optical properties of ZnO rods hydrothermally formed on polyethersulfone substrates

International Nuclear Information System (INIS)

Shin, Chang Mi; Jang, Jin Tak; Kim, Chang Yong; Ryu, Hyuk Hyun; Lee, Won Jae; Chang, Ji Ho; Son, Chang Sik; Choi, Hee Lack

2012-01-01

Various unique ZnO morphologies, such as cigar-like and belt-like structures and microrod and nanorod structures, were formed on flexible polyethersulfone (PES) substrates by using a low temperature hydrothermal route. The structural properties of ZnO depended highly on the precursor concentration. The effect of a thin ZnO seed layer deposited the on PES substrate by using atomic layer deposition on the structural and the optical properties of ZnO hydrothermally grown on the ZnO seed layer/PES substrates was studied. Field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and photoluminescence (PL) measurements were employed to analyze the characteristics of hydrothermally-grown ZnO. The diameter of the ZnO nanorods grown on the ZnO seed layer/PES substrates increased with increasing precursor concentration from 0.025 to 0.125 M due to the Ostwald ripening process. ZnO hydrothermally-grown on the ZnO seed layer/PES substrates at a low precursor concentration showed better structural properties than ZnO formed without a seed layer. Well-formed ZnO nanorods deposited on the ZnO seed layer/PES substrates showed two PL peaks, one in the ultraviolet and the other in the visible region, whereas horizontally positioned ZnO formed on the PES substrate in the absence of a seed layer emitted only one broad PL peak in the violet region. The ZnO grown on PES substrates in this work can be used as high-quality transparent electrodes for solar cells fabricated on flexible substrates.

Study on reinforced concrete beams with helical transverse reinforcement

Science.gov (United States)

Kaarthik Krishna, N.; Sandeep, S.; Mini, K. M.

2018-02-01

In a Reinforced Concrete (R.C) structure, major reinforcement is used for taking up tensile stresses acting on the structure due to applied loading. The present paper reports the behavior of reinforced concrete beams with helical reinforcement (transverse reinforcement) subjected to monotonous loading by 3-point flexure test. The results were compared with identically similar reinforced concrete beams with rectangular stirrups. During the test crack evolution, load carrying capacity and deflection of the beams were monitored, analyzed and compared. Test results indicate that the use of helical reinforcement provides enhanced load carrying capacity and a lower deflection proving to be more ductile, clearly indicating the advantage in carrying horizontal loads. An analysis was also carried out using ANSYS software in order to compare the test results of both the beams.

Preparation of the Crosslinked Polyethersulfone Films by High Temperature Electron-Beam Irradiation

International Nuclear Information System (INIS)

Li, J.

2006-01-01

The aromatic polymers, mainly so called engineering plastics, were famed for the good stability under irradiation. However, high temperature irradiation of the aromatic polymers can result the crosslinked structure, due to the improved molecular mobility. Polyethersulfone (PES) is a wide used engineering plastic because of the high performance and high thermal stability. PES films were irradiated by electron-beam under nitrogen atmosphere above the glass transition temperature and then the covalently crosslinked PES (RX-PES) films were obtained. The irradiations were also performed at ambient temperature for comparison. The network structure formation of the RX-PES films was confirmed by the appearance of the gel, which were measured by soaking the irradiated PES films in the N,N-dimethylformamide (DMF) at room temperature. When the PES films were irradiated to 300 kGy, there was gel appeared. The gel percent increased with the increasing in the absorbed dose, and saturated when the absorbed dose exceeded 1200 kGy. However, there was no gel formed for the PES films irradiated at ambient temperature even to 2250 kGy. The G(S) and G(X) were calculated according to the Y-crosslinking mechanism. The results values are consistent in error range. G(S) of 0.10 and G(X) of 0.23 were obtained. As calculated, almost all the macromolecular radicals produced by chain scission were used for crosslinking. Also, the glass transition temperature of the RX-PES films increased with the increasing in the absorbed doses, while the glass transition temperature of the PES films irradiated at ambient temperature decreased with the increasing in the absorbed doses. The blending films of the PES with FEP or ETFE were prepared and the high temperature irradiation effects were also studies

REINFORCED COMPOSITE PANEL

DEFF Research Database (Denmark)

2003-01-01

A composite panel having front and back faces, the panel comprising facing reinforcement, backing reinforcement and matrix material binding to the facing and backing reinforcements, the facing and backing reinforcements each independently comprising one or more reinforcing sheets, the facing rein...... by matrix material, the facing and backing reinforcements being interconnected to resist out-of-plane relative movement. The reinforced composite panel is useful as a barrier element for shielding structures, equipment and personnel from blast and/or ballistic impact damage....

Reinforcement Magnitude: An Evaluation of Preference and Reinforcer Efficacy

OpenAIRE

Trosclair-Lasserre, Nicole M; Lerman, Dorothea C; Call, Nathan A; Addison, Laura R; Kodak, Tiffany

2008-01-01

Consideration of reinforcer magnitude may be important for maximizing the efficacy of treatment for problem behavior. Nonetheless, relatively little is known about children's preferences for different magnitudes of social reinforcement or the extent to which preference is related to differences in reinforcer efficacy. The purpose of the current study was to evaluate the relations among reinforcer magnitude, preference, and efficacy by drawing on the procedures and results of basic experimenta...

Enhanced biofouling resistance of polyethersulfone membrane surface modified with capsaicin derivative and itaconic acid

Energy Technology Data Exchange (ETDEWEB)

Wang, Jian [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100 (China); College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100 (China); Gao, Xueli, E-mail: gxl_ouc@126.com [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100 (China); College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100 (China); Wang, Qun; Sun, Haijing; Wang, Xiaojuan [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100 (China); College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100 (China); Gao, Congjie, E-mail: gaocjie@ouc.edu.cn [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100 (China); College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100 (China)

2015-11-30

Graphical abstract: - Highlights: • PES membrane was modified with a capsaicin derivative. • UV-assisted graft polymerization was carried out on membrane surface. • The capsaicin derivative modified membrane shows better antibiofouling property. - Abstract: The culprit of biofouling is the reproduction of viable microorganisms on the membrane surface. Recently, functionalization of membrane surface with natural antibacterial agents has drawn great attention. This work presents the fabrication of antibiofouling polyethersulfone (PES) ultrafiltration (UF) membranes by UV-assisted photo grafting of capsaicin derivative (N-(4-hydroxy-3-methoxy-benzyl)-acrylamide, HMBA) and itaconic acid (IA) on the surface of PES membrane. Results of FTIR-ATR, water static contact angle (WSCA) and atomic force microscopy (AFM) analysis confirmed the successful grafting of HMBA and IA on the membrane surface. We investigated the antifouling and antibacterial properties of these membranes using BSA and Escherichia coli as the test model, respectively. During a 150-min test, the modified membranes show much lower flux decline (42.7% for PES-g-1H0I, 22.2% for PES-g-1H1I and 7.7% for PES-g-1H5I) when compared with the pristine membrane (flux declined by 77%). The modified membranes exhibit excellent antibacterial activity (nearly 100%) when UV irradiation time was 6 min. The morphological study suggested that the E. coli on the pristine membrane showed a regular and smooth surface while that on the modified membrane was disrupted, which validated the antibacterial activity of the modified membranes.

Enhanced biofouling resistance of polyethersulfone membrane surface modified with capsaicin derivative and itaconic acid

International Nuclear Information System (INIS)

Wang, Jian; Gao, Xueli; Wang, Qun; Sun, Haijing; Wang, Xiaojuan; Gao, Congjie

2015-01-01

Graphical abstract: - Highlights: • PES membrane was modified with a capsaicin derivative. • UV-assisted graft polymerization was carried out on membrane surface. • The capsaicin derivative modified membrane shows better antibiofouling property. - Abstract: The culprit of biofouling is the reproduction of viable microorganisms on the membrane surface. Recently, functionalization of membrane surface with natural antibacterial agents has drawn great attention. This work presents the fabrication of antibiofouling polyethersulfone (PES) ultrafiltration (UF) membranes by UV-assisted photo grafting of capsaicin derivative (N-(4-hydroxy-3-methoxy-benzyl)-acrylamide, HMBA) and itaconic acid (IA) on the surface of PES membrane. Results of FTIR-ATR, water static contact angle (WSCA) and atomic force microscopy (AFM) analysis confirmed the successful grafting of HMBA and IA on the membrane surface. We investigated the antifouling and antibacterial properties of these membranes using BSA and Escherichia coli as the test model, respectively. During a 150-min test, the modified membranes show much lower flux decline (42.7% for PES-g-1H0I, 22.2% for PES-g-1H1I and 7.7% for PES-g-1H5I) when compared with the pristine membrane (flux declined by 77%). The modified membranes exhibit excellent antibacterial activity (nearly 100%) when UV irradiation time was 6 min. The morphological study suggested that the E. coli on the pristine membrane showed a regular and smooth surface while that on the modified membrane was disrupted, which validated the antibacterial activity of the modified membranes.

Experimental investigation and modeling of industrial oily wastewater treatment using modified polyethersulfone ultrafiltration hollow fiber membranes

International Nuclear Information System (INIS)

Salahi, Abdolhamid; Mohammadi, Toraj; Behbahani, Reza Mosayebi; Hemmati, Mahmood

2015-01-01

Hollow fiber membranes were prepared from polyethersulfone/additives/NMP and DMSO system via phase inversion induced by precipitation in non-solvent coagulation bath. The interaction effects of polyethylene-glycol (PEG), propionic-acid (PA), Tween-20, PEG molecular weight and polyvinyl-pyrrolidone (PVP) on morphology and performance of synthesized membranes were investigated. Taguchi method (L 16 orthogonal array) was used initially to plan a minimum number of experiments. 32 membranes were synthesized (with two replications) and their permeation flux and TOC rejection properties to oily wastewater treatment were studied. The obtained results indicated that addition of PA to spinning dope decreases flux while it increases TOC rejection of prepared membranes. Also, the result shows that addition of PVP, Tween-20 and PEG content in spinning dope enhances permeation flux while reducing TOC rejection. The obtained results indicated that the synthesized membranes was effective and suitable for treatment of the oily wastewater to achieve up to 92.6, 98.2, and 98.5% removal of TOC, TSS, and OGC, respectively with a flux of 247.19 L/(m 2 h). Moreover, Hermia's models were used for permeation flux decline prediction. Experimental data and models predictions were compared. The results showed that there is reasonable agreement between experimental data and the cake layer model followed by the intermediate blocking model

Experimental investigation and modeling of industrial oily wastewater treatment using modified polyethersulfone ultrafiltration hollow fiber membranes

Energy Technology Data Exchange (ETDEWEB)

Salahi, Abdolhamid; Mohammadi, Toraj [Iran University of Science and Technology (IUST), Tehran (Iran, Islamic Republic of); Behbahani, Reza Mosayebi [Petroleum University of Technology (PUT), Ahwaz (Iran, Islamic Republic of); Hemmati, Mahmood [Research Institute of Petroleum Industry, Tehran (Iran, Islamic Republic of)

2015-06-15

Hollow fiber membranes were prepared from polyethersulfone/additives/NMP and DMSO system via phase inversion induced by precipitation in non-solvent coagulation bath. The interaction effects of polyethylene-glycol (PEG), propionic-acid (PA), Tween-20, PEG molecular weight and polyvinyl-pyrrolidone (PVP) on morphology and performance of synthesized membranes were investigated. Taguchi method (L{sub 16} orthogonal array) was used initially to plan a minimum number of experiments. 32 membranes were synthesized (with two replications) and their permeation flux and TOC rejection properties to oily wastewater treatment were studied. The obtained results indicated that addition of PA to spinning dope decreases flux while it increases TOC rejection of prepared membranes. Also, the result shows that addition of PVP, Tween-20 and PEG content in spinning dope enhances permeation flux while reducing TOC rejection. The obtained results indicated that the synthesized membranes was effective and suitable for treatment of the oily wastewater to achieve up to 92.6, 98.2, and 98.5% removal of TOC, TSS, and OGC, respectively with a flux of 247.19 L/(m{sup 2}h). Moreover, Hermia's models were used for permeation flux decline prediction. Experimental data and models predictions were compared. The results showed that there is reasonable agreement between experimental data and the cake layer model followed by the intermediate blocking model.

Evaluation of polyethersulfone performance for the microextraction of polar chlorinated herbicides from environmental water samples.

Science.gov (United States)

Prieto, Ailette; Rodil, Rosario; Quintana, José Benito; Cela, Rafael; Möder, Monika; Rodríguez, Isaac

2014-05-01

In this work, the suitability of bulk polyethersulfone (PES) for sorptive microextraction of eight polar, chlorinated phenoxy acids and dicamba from environmental water samples is assessed and the analytical features of the optimized method are compared to those reported for other microextraction techniques. Under optimized conditions, extractions were performed with samples (18 mL) adjusted at pH 2 and containing a 30% (w/v) of sodium chloride, using a tubular PES sorbent (1 cm length × 0.7 mm o.d., sorbent volume 8 µL). Equilibrium conditions were achieved after 3h of direct sampling, with absolute extraction efficiencies ranging from 39 to 66%, depending on the compound. Analytes were recovered soaking the polymer with 0.1 mL of ethyl acetate, derivatized and determined by gas chromatography-mass spectrometry (GC-MS). Achieved quantification limits (LOQs) varied between 0.005 and 0.073 ng mL(-1). After normalization with the internal surrogate (IS), the efficiency of the extraction was only moderately affected by the particular characteristics of different water samples (surface and sewage water); thus, pseudo-external calibration, using spiked ultrapure water solutions, can be used as quantification technique. The reduced cost of the PES polymer allowed considering it as a disposable sorbent, avoiding variations in the performance of the extraction due to cross-contamination problems and/or surface modification with usage. Copyright © 2014 Elsevier B.V. All rights reserved.

Reinforced sulphur concrete

NARCIS (Netherlands)

2014-01-01

Reinforced sulphur concrete wherein one or more metal reinforcing members are in contact with sulphur concrete is disclosed. The reinforced sulphur concrete comprises an adhesion promoter that enhances the interaction between the sulphur and the one or more metal reinforcing members.

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

Reinforcement Magnitude: An Evaluation of Preference and Reinforcer Efficacy

Science.gov (United States)

Trosclair-Lasserre, Nicole M.; Lerman, Dorothea C.; Call, Nathan A.; Addison, Laura R.; Kodak, Tiffany

2008-01-01

Consideration of reinforcer magnitude may be important for maximizing the efficacy of treatment for problem behavior. Nonetheless, relatively little is known about children's preferences for different magnitudes of social reinforcement or the extent to which preference is related to differences in reinforcer efficacy. The purpose of the current…

Autoshaping Chicks with Heat Reinforcement: The Role of Stimulus-Reinforcer and Response-Reinforcer Relations

Science.gov (United States)

Wasserman, Edward A.; And Others

1975-01-01

The present series of experiments attempted to analyze more fully the contributions of stimulus-reinforcer and response-reinforcer relations to autoshaping within a single conditioning situation. (Author)

Genomic Signatures of Reinforcement

Directory of Open Access Journals (Sweden)

Austin G. Garner

2018-04-01

Full Text Available Reinforcement is the process by which selection against hybridization increases reproductive isolation between taxa. Much research has focused on demonstrating the existence of reinforcement, yet relatively little is known about the genetic basis of reinforcement or the evolutionary conditions under which reinforcement can occur. Inspired by reinforcement’s characteristic phenotypic pattern of reproductive trait divergence in sympatry but not in allopatry, we discuss whether reinforcement also leaves a distinct genomic pattern. First, we describe three patterns of genetic variation we expect as a consequence of reinforcement. Then, we discuss a set of alternative processes and complicating factors that may make the identification of reinforcement at the genomic level difficult. Finally, we consider how genomic analyses can be leveraged to inform if and to what extent reinforcement evolved in the face of gene flow between sympatric lineages and between allopatric and sympatric populations of the same lineage. Our major goals are to understand if genome scans for particular patterns of genetic variation could identify reinforcement, isolate the genetic basis of reinforcement, or infer the conditions under which reinforcement evolved.

Genomic Signatures of Reinforcement

Science.gov (United States)

Goulet, Benjamin E.

2018-01-01

Reinforcement is the process by which selection against hybridization increases reproductive isolation between taxa. Much research has focused on demonstrating the existence of reinforcement, yet relatively little is known about the genetic basis of reinforcement or the evolutionary conditions under which reinforcement can occur. Inspired by reinforcement’s characteristic phenotypic pattern of reproductive trait divergence in sympatry but not in allopatry, we discuss whether reinforcement also leaves a distinct genomic pattern. First, we describe three patterns of genetic variation we expect as a consequence of reinforcement. Then, we discuss a set of alternative processes and complicating factors that may make the identification of reinforcement at the genomic level difficult. Finally, we consider how genomic analyses can be leveraged to inform if and to what extent reinforcement evolved in the face of gene flow between sympatric lineages and between allopatric and sympatric populations of the same lineage. Our major goals are to understand if genome scans for particular patterns of genetic variation could identify reinforcement, isolate the genetic basis of reinforcement, or infer the conditions under which reinforcement evolved. PMID:29614048

Habituation of reinforcer effectiveness

OpenAIRE

David R Lloyd; David R Lloyd; Douglas J Medina; Larry W Hawk; Whitney D Fosco; Jerry B Richards

2014-01-01

In this paper we propose an integrative model of habituation of reinforcer effectiveness (HRE) that links behavioral and neural based explanations of reinforcement. We argue that habituation of reinforcer effectiveness (HRE) is a fundamental property of reinforcing stimuli. Most reinforcement models implicitly suggest that the effectiveness of a reinforcer is stable across repeated presentations. In contrast, an HRE approach predicts decreased effectiveness due to repeated presentation. We ar...

Structural Behavior of Concrete Beams Reinforced with Basalt Fiber Reinforced Polymer (BFRP) Bars

Science.gov (United States)

Ovitigala, Thilan

The main challenge for civil engineers is to provide sustainable, environmentally friendly and financially feasible structures to the society. Finding new materials such as fiber reinforced polymer (FRP) material that can fulfill the above requirements is a must. FRP material was expensive and it was limited to niche markets such as space shuttles and air industry in the 1960s. Over the time, it became cheaper and spread to other industries such as sporting goods in the 1980-1990, and then towards the infrastructure industry. Design and construction guidelines are available for carbon fiber reinforced polymer (CFRP), aramid fiber reinforced polymer (AFRP) and glass fiber reinforced polymer (GFRP) and they are currently used in structural applications. Since FRP is linear elastic brittle material, design guidelines for the steel reinforcement are not valid for FRP materials. Corrosion of steel reinforcement affects the durability of the concrete structures. FRP reinforcement is identified as an alternative to steel reinforcement in corrosive environments. Although basalt fiber reinforced polymer (BFRP) has many advantages over other FRP materials, but limited studies have been done. These studies didn't include larger BFRP bar diameters that are mostly used in practice. Therefore, larger beam sizes with larger BFRP reinforcement bar diameters are needed to investigate the flexural and shear behavior of BFRP reinforced concrete beams. Also, shear behavior of BFRP reinforced concrete beams was not yet studied. Experimental testing of mechanical properties and bond strength of BFRP bars and flexural and shear behavior of BFRP reinforced concrete beams are needed to include BFRP reinforcement bars in the design codes. This study mainly focuses on the use of BFRP bars as internal reinforcement. The test results of the mechanical properties of BFRP reinforcement bars, the bond strength of BFRP reinforcement bars, and the flexural and shear behavior of concrete beams

Morphology modification of polyethersulfone membrane from montmorillonite clay presence; Modificacao da morfologia de membrana de polietersulfona a partir da presenca de argila montmorilonita

Energy Technology Data Exchange (ETDEWEB)

Ferreira, R.S.B.; Oliveira, S.S.L.; Leite, A.M.D.; Araujo, E.M.; Lira, H.L., E-mail: edcleide.araujo@dema.ufcg.edu.br [Universidade Federal de Campina Grande (UAEMa/CCT/UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais; Universidade Federal do Rio Grande do Norte (ECT/UFRN), Natal, RN (Brazil). Escola de Ciencias e Tecnologia

2016-07-01

The objective of this work is to produce hollow fiber membranes of polyethersulfone from the formation of hybrids with montmorillonite national clay (3 and 5% Brasgel PA), with the intention of modifying the morphology and improving the flow properties of the PES membrane. Initially, flat membranes were produced for characterization by X-ray diffraction (XRD) and contact angle. By XRD it was evident that membrane production and clay influenced the crystallinity of the polymer. The measurement of the contact angle indicated that the incorporation of clay promoted a change in membrane hydrophilicity, being more evident for with the 3% of MMT. By means of scanning electron microscopy (SEM) it was evidenced that the clay modified the morphology of the membrane, having a better distribution of the pores and the 'fingers'. The flow measurements showed that the membrane containing 3% of MMT had a higher permeability to distilled water, indicating its potential for the treatment of liquid effluents. (author)

Surface Functionalization of Polyethersulfone Membrane with Quaternary Ammonium Salts for Contact-Active Antibacterial and Anti-Biofouling Properties

Directory of Open Access Journals (Sweden)

Xiao Hu

2016-05-01

Full Text Available Biofilm is a significant cause for membrane fouling. Antibacterial-coated surfaces can inhibit biofilm formation by killing bacteria. In this study, polyethersulfone (PES microfiltration membrane was photografted by four antibiotic quaternary ammonium compounds (QACs separately, which were synthesized from dimethylaminoethyl methacrylate (DMAEMA by quaternization with butyl bromide (BB, octyl bromide (OB, dodecyl bromide (DB, or hexadecyl bromide (HB. XPS, ATR-FTIR, and SEM were used to confirm the surfaces’ composition and morphology. After modification, the pores on PES-g-DMAEMA-BB and PES-g-DMAEMA-OB were blocked, while PES-g-DMAEMA-DB and PES-g-DMAEMA-HB were retained. We supposed that DMAEMA-BB and DMAEMA-OB aggregated on the membrane surface due to the activities of intermolecular or intramolecular hydrogen bonds. Bacteria testing found the antibacterial activities of the membranes increased with the length of the substituted alkyl chain. Correspondingly, little bacteria were observed on PES-g-DMAEMA-DB and PES-g-DMAEMA-HB by SEM. The antifouling properties were investigated by filtration of a solution of Escherichia coli. Compared with the initial membrane, PES-g-DMAEMA-DB and PES-g-DMAEMA-HB showed excellent anti-biofouling performance with higher relative flux recovery (RFR of 88.3% and 92.7%, respectively. Thus, surface functionalization of the PES membrane with QACs can prevent bacteria adhesion and improve the anti-biofouling activity by the contact-active antibacterial property.

Proton exchange membranes from sulfonated polyetheretherketone and sulfonated polyethersulfone-cardo blends: Conductivity, water sorption and permeation properties

International Nuclear Information System (INIS)

Li, Yongli; Nguyen, Quang Trong; Schaetzel, Pierre; Lixon-Buquet, Camille; Colasse, Laurent; Ratieuville, Vincent

2013-01-01

Five blend membranes were prepared by solvent evaporation from solutions of the synthesized sulfonated polyetheretherketone (SPEEK) and sulfonated polyethersulfone-cardo (SPESc). Their ion exchange capacity and degree of sulfonation determined by acid–base titration and by thermogravimetric analysis were consistent. The blends glass transition behavior obtained by differential scanning calorimetry suggests that the two sulfonated polymers are compatible in the whole composition range. The values of the activation energy for proton transport determined by conductivity measurements on the SPEEK-based blend membranes were in the range of 13–34 kJ mol −1 , which suggest a mixed transport mechanism that involves both proton jumps on ionic sites and water of hydration and diffusion of proton–water complex in hydrophilic domains. The water vapor sorption in the membranes exhibits sigmoid-shape isotherms which were well fitted by the “new dual mode sorption” model, and the fitted parameters values were successfully used to model the change in the water permeation flux with the upstream water activity using the first Fick's diffusion equation. The fast increase in the permeation flux beyond a critical value of activity (0.5) was owing to the exponential concentration-dependent diffusion coefficient. These modelings allowed us to show a strong increase in the limit diffusion coefficient of water and a decrease in the water-diffusion plasticization coefficient with the SPEEK content in the polymer blends

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...

Adapting without reinforcement.

Science.gov (United States)

Kheifets, Aaron; Gallistel, C Randy

2012-11-01

Our data rule out a broad class of behavioral models in which behavioral change is guided by differential reinforcement. To demonstrate this, we showed that the number of reinforcers missed before the subject shifted its behavior was not sufficient to drive behavioral change. What's more, many subjects shifted their behavior to a more optimal strategy even when they had not yet missed a single reinforcer. Naturally, differential reinforcement cannot be said to drive a process that shifts to accommodate to new conditions so adeptly that it doesn't miss a single reinforcer: it would have no input on which to base this shift.

Investigations of timing during the schedule and reinforcement intervals with wheel-running reinforcement.

Science.gov (United States)

Belke, Terry W; Christie-Fougere, Melissa M

2006-11-01

Across two experiments, a peak procedure was used to assess the timing of the onset and offset of an opportunity to run as a reinforcer. The first experiment investigated the effect of reinforcer duration on temporal discrimination of the onset of the reinforcement interval. Three male Wistar rats were exposed to fixed-interval (FI) 30-s schedules of wheel-running reinforcement and the duration of the opportunity to run was varied across values of 15, 30, and 60s. Each session consisted of 50 reinforcers and 10 probe trials. Results showed that as reinforcer duration increased, the percentage of postreinforcement pauses longer than the 30-s schedule interval increased. On probe trials, peak response rates occurred near the time of reinforcer delivery and peak times varied with reinforcer duration. In a second experiment, seven female Long-Evans rats were exposed to FI 30-s schedules leading to 30-s opportunities to run. Timing of the onset and offset of the reinforcement period was assessed by probe trials during the schedule interval and during the reinforcement interval in separate conditions. The results provided evidence of timing of the onset, but not the offset of the wheel-running reinforcement period. Further research is required to assess if timing occurs during a wheel-running reinforcement period.

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 .

Habituation of reinforcer effectiveness

Directory of Open Access Journals (Sweden)

David R Lloyd

2014-01-01

Full Text Available In this paper we propose an integrative model of habituation of reinforcer effectiveness (HRE that links behavioral and neural based explanations of reinforcement. We argue that habituation of reinforcer effectiveness (HRE is a fundamental property of reinforcing stimuli. Most reinforcement models implicitly suggest that the effectiveness of a reinforcer is stable across repeated presentations. In contrast, an HRE approach predicts decreased effectiveness due to repeated presentation. We argue that repeated presentation of reinforcing stimuli decreases their effectiveness and that these decreases are described by the behavioral characteristics of habituation (McSweeney and Murphy, 2009;Rankin et al., 2009. We describe a neural model that postulates a positive association between dopamine neurotransmission and HRE. We present evidence that stimulant drugs, which artificially increase dopamine neurotransmission, disrupt (slow normally occurring HRE and also provide evidence that stimulant drugs have differential effects on operant responding maintained by reinforcers with rapid vs. slow HRE rates. We hypothesize that abnormal HRE due to genetic and/or environmental factors may underlie some behavioral disorders. For example, recent research indicates that slow-HRE is predictive of obesity. In contrast ADHD may reflect ‘accelerated-HRE’. Consideration of HRE is important for the development of effective reinforcement based treatments. Finally, we point out that most of the reinforcing stimuli that regulate daily behavior are non-consumable environmental/social reinforcers which have rapid-HRE. The almost exclusive use of consumable reinforcers with slow-HRE in pre-clinical studies with animals may have caused the importance of HRE to be overlooked. Further study of reinforcing stimuli with rapid-HRE is needed in order to understand how habituation and reinforcement interact and regulate behavior.

Enhancing corrosion resistance of reinforced concrete structures with hybrid fiber reinforced concrete

International Nuclear Information System (INIS)

Blunt, J.; Jen, G.; Ostertag, C.P.

2015-01-01

Highlights: • Reinforced concrete beams were subjected to cyclic flexural loading. • Hybrid fiber reinforced composites were effective in reducing corrosion rates. • Crack resistance due to fibers increased corrosion resistance of steel rebar. • Galvanic corrosion measurements underestimated corrosion rates. • Polarization resistance measurements predicted mass loss more accurately. - Abstract: Service loads well below the yield strength of steel reinforcing bars lead to cracking of reinforced concrete. This paper investigates whether the crack resistance of Hybrid Fiber Reinforced Concrete (HyFRC) reduces the corrosion rate of steel reinforcing bars in concrete after cyclic flexural loading. The reinforcing bars were extracted to examine their surface for corrosion and compare microcell and macrocell corrosion mass loss estimates against direct gravimetric measurements. A delay in corrosion initiation and lower active corrosion rates were observed in the HyFRC beam specimens when compared to reinforced specimens containing plain concrete matrices cycled at the same flexural load

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.

Theoretical and numerical analysis of reinforced concrete beams with confinement reinforcement

Directory of Open Access Journals (Sweden)

R. G. Delalibera

Full Text Available This paper discusses the use of confinement in over-reinforced concrete beams. This reinforcement consists of square stirrups, placed in the compression zone of the beam cross-section, in order to improve its ductility. A parametric numerical study is initially performed, using a finite element computational program that considers the material nonlinearities and the confinement effect. To investigate the influence of the transverse reinforcing ratio on the beam ductility, an experimental program was also conducted. Four over-reinforced beams were tested; three beam specimens with additional transverse reinforcement to confine the beams, and one without it. All specimens were fabricated with a concrete designed for a compressive strength of 25 MPa. The experimental results show that the post-peak ductility factor is proportional to the confining reinforcement ratio, however the same is not observed for the pre-peak ductility factor, which varied randomly with changes in the confining reinforcement ratio. It was also observed from the experiments that the confinement effect tends to be smaller close to the beam neutral axis.

Habituation of reinforcer effectiveness.

Science.gov (United States)

Lloyd, David R; Medina, Douglas J; Hawk, Larry W; Fosco, Whitney D; Richards, Jerry B

2014-01-09

In this paper we propose an integrative model of habituation of reinforcer effectiveness (HRE) that links behavioral- and neural-based explanations of reinforcement. We argue that HRE is a fundamental property of reinforcing stimuli. Most reinforcement models implicitly suggest that the effectiveness of a reinforcer is stable across repeated presentations. In contrast, an HRE approach predicts decreased effectiveness due to repeated presentation. We argue that repeated presentation of reinforcing stimuli decreases their effectiveness and that these decreases are described by the behavioral characteristics of habituation (McSweeney and Murphy, 2009; Rankin etal., 2009). We describe a neural model that postulates a positive association between dopamine neurotransmission and HRE. We present evidence that stimulant drugs, which artificially increase dopamine neurotransmission, disrupt (slow) normally occurring HRE and also provide evidence that stimulant drugs have differential effects on operant responding maintained by reinforcers with rapid vs. slow HRE rates. We hypothesize that abnormal HRE due to genetic and/or environmental factors may underlie some behavioral disorders. For example, recent research indicates that slow-HRE is predictive of obesity. In contrast ADHD may reflect "accelerated-HRE." Consideration of HRE is important for the development of effective reinforcement-based treatments. Finally, we point out that most of the reinforcing stimuli that regulate daily behavior are non-consumable environmental/social reinforcers which have rapid-HRE. The almost exclusive use of consumable reinforcers with slow-HRE in pre-clinical studies with animals may have caused the importance of HRE to be overlooked. Further study of reinforcing stimuli with rapid-HRE is needed in order to understand how habituation and reinforcement interact and regulate behavior.

Transparent SiON/Ag/SiON multilayer passivation grown on a flexible polyethersulfone substrate using a continuous roll-to-roll sputtering system

Science.gov (United States)

2012-01-01

We have investigated the characteristics of a silicon oxynitride/silver/silicon oxynitride [SiON/Ag/SiON] multilayer passivation grown using a specially designed roll-to-roll [R2R] sputtering system on a flexible polyethersulfone substrate. Optical, structural, and surface properties of the R2R grown SiON/Ag/SiON multilayer were investigated as a function of the SiON thickness at a constant Ag thickness of 12 nm. The flexible SiON/Ag/SiON multilayer has a high optical transmittance of 87.7% at optimized conditions due to the antireflection and surface plasmon effects in the oxide-metal-oxide structure. The water vapor transmission rate of the SiON/Ag/SiON multilayer is 0.031 g/m2 day at an optimized SiON thickness of 110 nm. This indicates that R2R grown SiON/Ag/SiON is a promising thin-film passivation for flexible organic light-emitting diodes and flexible organic photovoltaics due to its simple and low-temperature process. PMID:22221400

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

Axial Compression Tests on Corroded Reinforced Concrete Columns Consolidated with Fibre Reinforced Polymers

Directory of Open Access Journals (Sweden)

Bin Ding

2017-06-01

Full Text Available Reinforced concrete structure featured by strong bearing capacity, high rigidity, good integrity, good fire resistance, and extensive applicability occupies a mainstream position in contemporary architecture. However, with the development of social economy, people need higher requirements on architectural structure; durability, especially, has been extensively researched. Because of the higher requirement on building material, ordinary reinforced concrete structure has not been able to satisfy the demand. As a result, some new materials and structures have emerged, for example, fibre reinforced polymers. Compared to steel reinforcement, fibre reinforced polymers have many advantages, such as high tensile strength, good durability, good shock absorption, low weight, and simple construction. The application of fibre reinforced polymers in architectural structure can effectively improve the durability of the concrete structure and lower the maintenance, reinforcement, and construction costs in severe environments. Based on the concepts of steel tube concrete, fibre reinforced composite material confined concrete, and fibre reinforced composite material tubed concrete, this study proposes a novel composite structure, i.e., fibre reinforced composite material and steel tube concrete composite structure. The structure was developed by pasting fibre around steel tube concrete and restraining core concrete using fibre reinforced composite material and steel tubes. The bearing capacity and ultimate deformation capacity of the structure was tested using column axial compression test.

Improved human endometrial stem cells differentiation into functional hepatocyte-like cells on a glycosaminoglycan/collagen-grafted polyethersulfone nanofibrous scaffold.

Science.gov (United States)

Khademi, Farzaneh; Ai, Jafar; Soleimani, Masoud; Verdi, Javad; Mohammad Tavangar, Seyed; Sadroddiny, Esmaeil; Massumi, Mohammad; Mahmoud Hashemi, Seyed

2017-11-01

Liver tissue engineering (TE) is rapidly emerging as an effective technique which combines engineering and biological processes to compensate for the shortage of damaged or destroyed liver tissues. We examined the viability, differentiation, and integration of hepatocyte-like cells on an electrospun polyethersulfone (PES) scaffold, derived from human endometrial stem cells (hEnSCs). Natural polymers were separately grafted on plasma-treated PES nanofibers, that is, collagen, heparan sulfate (HS) and collagen-HS. Galactosilated PES (PES-Gal) nanofibrous were created. The engineering and cell growth parameters were considered and compared with each sample. The cellular studies revealed increased cell survival, attachment, and normal morphology on the bioactive natural polymer-grafted scaffolds after 30 days of hepatic differentiation. The chemical and molecular assays displayed hepatocyte differentiation. These cells were also functional, showing glycogen storage, α-fetoprotein, and albumin secretion. The HS nanoparticle-grafted PES nanofibers demonstrated a high rate of cell proliferation, differentiation, and integration. Based on the observations mentioned above, engineered tissue is a good option in the future, for the commercial production of three-dimensional liver tissues for clinical purposes. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2516-2529, 2017. © 2016 Wiley Periodicals, Inc.

Flexural strength using Steel Plate, Carbon Fiber Reinforced Polymer (CFRP) and Glass Fiber Reinforced Polymer (GFRP) on reinforced concrete beam in building technology

Science.gov (United States)

Tarigan, Johannes; Patra, Fadel Muhammad; Sitorus, Torang

2018-03-01

Reinforced concrete structures are very commonly used in buildings because they are cheaper than the steel structures. But in reality, many concrete structures are damaged, so there are several ways to overcome this problem, by providing reinforcement with Fiber Reinforced Polymer (FRP) and reinforcement with steel plates. Each type of reinforcements has its advantages and disadvantages. In this study, researchers discuss the comparison between flexural strength of reinforced concrete beam using steel plates and Fiber Reinforced Polymer (FRP). In this case, the researchers use Carbon Fiber Reinforced Polymer (CFRP) and Glass Fiber Reinforced Polymer (GFRP) as external reinforcements. The dimension of the beams is 15 x 25 cm with the length of 320 cm. Based on the analytical results, the strength of the beam with CFRP is 1.991 times its initial, GFRP is 1.877 times while with the steel plate is 1.646 times. Based on test results, the strength of the beam with CFRP is 1.444 times its initial, GFRP is 1.333 times while the steel plate is 1.167 times. Based on these test results, the authors conclude that beam with CFRP is the best choice for external reinforcement in building technology than the others.

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

Marcelo Caetano : política económica e modernização

Directory of Open Access Journals (Sweden)

María Fernanda Rollo

2007-01-01

Full Text Available Con Marcelo Caetano en el poder, dentro de lo que él mismo denominó «renovación en la continuidad» y manteniéndose sin embargo los grandes objetivos en materia económica, los nuevos términos en que se planteó la prosecución de la modernización de la economía y de la industria portuguesas fueron efectivamente (aunque transitoriamente y sin gran éxito alterados. Las expectativas eran ambiciosas. Las principales «novedades económicas» del marcelismo se reflejaron en el campo de la política económica, acentuando la apuesta en el abatimiento del proteccionismo interno y externo y en la apertura al exterior. Se intentó estimular la inversión extranjera, combinándola con la apuesta por la aproximación a Europa, lo que se tradujo en un compromiso mayor en materia de cooperación económica, que facilitó la firma del acuerdo de libre comercio con la CEE en 1972.With Marcelo Caetano in power, and within the framework of what he himself phrased as «renovation in continuity», despite the fact that the key economic goals were carried on, the new terms in which the course of the modernization of Portuguese economy and industry was inscribed were truly (albeit provisionally and with no great success changed. The expectations were ambitious, laying their bets on a wide-ranging set of reforms. Marcelism’s main «economic novelties» had an effect on economic policy, reinforcing its endeavours to hold back the internal and external protectionism and to encourage the opening up to the outside world. This policy sought to motivate foreign investment, combining it with the aim of getting closer to Europe, which resulted in a more committed involvement in matters of economic cooperation, facilitating the celebration of the free trade agreement with EEC in 1972. Great effort was put into renovating strategies for industry. In that regard, two important novelties stand out: the creation of the Pólo de Sines and the promulgation of the Law of

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...

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.

Experimental analysis of reinforced concrete beams strengthened in bending with carbon fiber reinforced polymer

Directory of Open Access Journals (Sweden)

M. M. VIEIRA

Full Text Available The use of carbon fiber reinforced polymer (CFRP has been widely used for the reinforcement of concrete structures due to its practicality and versatility in application, low weight, high tensile strength and corrosion resistance. Some construction companies use CFRP in flexural strengthening of reinforced concrete beams, but without anchor systems. Therefore, the aim of this study is analyze, through an experimental program, the structural behavior of reinforced concrete beams flexural strengthened by CFRP without anchor fibers, varying steel reinforcement and the amount of carbon fibers reinforcement layers. Thus, two groups of reinforced concrete beams were produced with the same geometric feature but with different steel reinforcement. Each group had five beams: one that is not reinforced with CFRP (reference and other reinforced with two, three, four and five layers of carbon fibers. Beams were designed using a computational routine developed in MAPLE software and subsequently tested in 4-point points flexural test up to collapse. Experimental tests have confirmed the effectiveness of the reinforcement, ratifying that beams collapse at higher loads and lower deformation as the amount of fibers in the reinforcing layers increased. However, the increase in the number of layers did not provide a significant increase in the performance of strengthened beams, indicating that it was not possible to take full advantage of strengthening applied due to the occurrence of premature failure mode in the strengthened beams for pullout of the cover that could have been avoided through the use of a suitable anchoring system for CFRP.

Reinforcement Schedules in a Verbal Reinforcement Combination and Renection-Impulsivity

OpenAIRE

TAMASE, Koji; UEDA, Masako

1986-01-01

It was predicted that higher proportion of the negative reinforcement "Wrong" than that of the positive reinforcement "Right" in a reinforcement combination will produce higher proportion of the correct response and this trend will be greater in reflective children than in impulsive children. From 140 kindergarten children 30 reflective and 30 impulsive children were selected and they were given a two-hole marble-dropping task. The best performance in the ratio of correct responses was obtain...

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

Directory of Open Access Journals (Sweden)

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

Management of Reinforcement Corrosion

DEFF Research Database (Denmark)

Küter, André; Geiker, Mette Rica; Møller, Per

Reinforcement corrosion is the most important cause for deterioration of reinforced concrete structures, both with regard to costs and consequences. Thermodynamically consistent descriptions of corrosion mechanisms are expected to allow the development of innovative concepts for the management...... of reinforcement corrosion....

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

Effects of partial reinforcement and time between reinforced trials on terminal response rate in pigeon autoshaping.

Science.gov (United States)

Gottlieb, Daniel A

2006-03-01

Partial reinforcement often leads to asymptotically higher rates of responding and number of trials with a response than does continuous reinforcement in pigeon autoshaping. However, comparisons typically involve a partial reinforcement schedule that differs from the continuous reinforcement schedule in both time between reinforced trials and probability of reinforcement. Two experiments examined the relative contributions of these two manipulations to asymptotic response rate. Results suggest that the greater responding previously seen with partial reinforcement is primarily due to differential probability of reinforcement and not differential time between reinforced trials. Further, once established, differences in responding are resistant to a change in stimulus and contingency. Secondary response theories of autoshaped responding (theories that posit additional response-augmenting or response-attenuating mechanisms specific to partial or continuous reinforcement) cannot fully accommodate the current body of data. It is suggested that researchers who study pigeon autoshaping train animals on a common task prior to training them under different conditions.

Influence of transverse reinforcement on perforation resistance of reinforced concrete slabs under hard missile impact

International Nuclear Information System (INIS)

Orbovic, Nebojsa; Sagals, Genadijs; Blahoianu, Andrei

2015-01-01

This paper describes the work conducted by the Canadian Nuclear Safety Commission (CNSC) related to the influence of transverse reinforcement on perforation capacity of reinforced concrete (RC) slabs under “hard” missile impact (impact with negligible missile deformations). The paper presents the results of three tests on reinforced concrete slabs conducted at VTT Technical Research Centre (Finland), along with the numerical simulations as well as a discussion of the current code provisions related to impactive loading. Transverse reinforcement is widely used for improving the shear and punching strength of concrete structures. However, the effect of this reinforcement on the perforation resistance under localized missile impact is still unclear. The goal of this paper is to fill the gap in the current literature related to this topic. Based on similar tests designed by the authors with missile velocity below perforation velocity, it was expected that transverse reinforcement would improve the perforation resistance. Three slabs were tested under almost identical conditions with the only difference being the transverse reinforcement. One slab was designed without transverse reinforcement, the second one with the transverse reinforcement in form of conventional stirrups with hooks and the third one with the transverse reinforcement in form of T-headed bars. Although the transverse reinforcement reduced the overall damage of the slabs (the rear face scabbing), the conclusion from the tests is that the transverse reinforcement does not have important influence on perforation capacity of concrete slabs under rigid missile impact. The slab with T-headed bars presented a slight improvement compared to the baseline specimen without transverse reinforcement. The slab with conventional stirrups presented slightly lower perforation capacity (higher residual missile velocity) than the slab without transverse reinforcement. In conclusion, the performed tests show slightly

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.

Finite element modelling of concrete beams reinforced with hybrid fiber reinforced bars

Science.gov (United States)

Smring, Santa binti; Salleh, Norhafizah; Hamid, NoorAzlina Abdul; Majid, Masni A.

2017-11-01

Concrete is a heterogeneous composite material made up of cement, sand, coarse aggregate and water mixed in a desired proportion to obtain the required strength. Plain concrete does not with stand tension as compared to compression. In order to compensate this drawback steel reinforcement are provided in concrete. Now a day, for improving the properties of concrete and also to take up tension combination of steel and glass fibre-reinforced polymer (GFRP) bars promises favourable strength, serviceability, and durability. To verify its promise and support design concrete structures with hybrid type of reinforcement, this study have investigated the load-deflection behaviour of concrete beams reinforced with hybrid GFRP and steel bars by using ATENA software. Fourteen beams, including six control beams reinforced with only steel or only GFRP bars, were analysed. The ratio and the ordinate of GFRP to steel were the main parameters investigated. The behaviour of these beams was investigated via the load-deflection characteristics, cracking behaviour and mode of failure. Hybrid GFRP-Steel reinforced concrete beam showed the improvement in both ultimate capacity and deflection concomitant to the steel reinforced concrete beam. On the other hand, finite element (FE) modelling which is ATENA were validated with previous experiment and promising the good result to be used for further analyses and development in the field of present study.

Malvaceae endémicas del Perú

Directory of Open Access Journals (Sweden)

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

Directory of Open Access Journals (Sweden)

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.

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...

Methods for producing reinforced carbon nanotubes

Science.gov (United States)

Ren, Zhifen [Newton, MA; Wen, Jian Guo [Newton, MA; Lao, Jing Y [Chestnut Hill, MA; Li, Wenzhi [Brookline, MA

2008-10-28

Methods for producing reinforced carbon nanotubes having a plurality of microparticulate carbide or oxide materials formed substantially on the surface of such reinforced carbon nanotubes composite materials are disclosed. In particular, the present invention provides reinforced carbon nanotubes (CNTs) having a plurality of boron carbide nanolumps formed substantially on a surface of the reinforced CNTs that provide a reinforcing effect on CNTs, enabling their use as effective reinforcing fillers for matrix materials to give high-strength composites. The present invention also provides methods for producing such carbide reinforced CNTs.

Carbon Fiber Reinforced Polymer Grids for Shear and End Zone Reinforcement in Bridge Beams

Science.gov (United States)

2018-01-01

Corrosion of reinforcing steel reduces life spans of bridges throughout the United States; therefore, using non-corroding carbon fiber reinforced polymer (CFRP) reinforcement is seen as a way to increase service life. The use of CFRP as the flexural ...

Moraceae endémicas del Perú

Directory of Open Access Journals (Sweden)

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

Directory of Open Access Journals (Sweden)

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.

Combining noncontingent reinforcement and differential reinforcement schedules as treatment for aberrant behavior.

OpenAIRE

Marcus, B A; Vollmer, T R

1996-01-01

Research has shown that noncontingent reinforcement (NCR) can be an effective behavior-reduction procedure when based on a functional analysis. The effects of NCR may be a result of elimination of the contingency between aberrant behavior and reinforcing consequences (extinction) or frequent and free access to reinforcers that may reduce the participant's motivation to engage in aberrant behaviors or mands. If motivation is momentarily reduced, behavior such as mands may not be sensitive to p...

Flexible indium zinc oxide/Ag/indium zinc oxide multilayer electrode grown on polyethersulfone substrate by cost-efficient roll-to-roll sputtering for flexible organic photovoltaics

International Nuclear Information System (INIS)

Park, Yong-Seok; Kim, Han-Ki

2010-01-01

The authors describe the preparation and characteristics of flexible indium zinc oxide (IZO)-Ag-IZO multilayer electrodes grown on flexible polyethersulfone (PES) substrates using a roll-to-roll sputtering system for use in flexible organic photovoltaics. By the continuous roll-to-roll sputtering of the bottom IZO, Ag, and top IZO layers at room temperature, they were able to fabricate a high quality IZO-Ag-IZO multilayer electrode with a sheet resistance of 6.15 ε/square, optical transmittance of 87.4%, and figure of merit value of 42.03x10 -3 Ω -1 on the PES substrate. In addition, the IZO-Ag-IZO multilayer electrode exhibited superior flexibility to the roll-to-roll sputter grown single ITO electrode due to the existence of a ductile Ag layer between the IZO layers and stable amorphous structure of the IZO film. Furthermore, the flexible organic solar cells (OSCs) fabricated on the roll-to-roll sputter grown IZO-Ag-IZO electrode showed higher power efficiency (3.51%) than the OSCs fabricated on the roll-to-roll sputter grown single ITO electrode (2.67%).

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.

Degradation of Waterfront Reinforced Concrete Structures

African Journals Online (AJOL)

Key words: Degradation, reinforced concrete, Dar es Salaam port. Abstract—One of the ... especially corrosion of the reinforcement. ... Corrosion of steel reinforcement contributes .... cracks along the line of reinforcement bars and most of the ...

Confinement of Reinforced-Concrete Columns with Non-Code Compliant Confining Reinforcement plus Supplemental Pen-Binder

Directory of Open Access Journals (Sweden)

Anang Kristianto

2012-11-01

Full Text Available One of the important requirements for earthquake resistant building related to confinement is the use of seismic hooks in the hoop or confining reinforcement of reinforced-concrete column elements. However, installation of a confining reinforcement with a 135-degree hook is not easy. Therefore, in practice, many construction workers apply a confining reinforcement with a 90-degreehook (non-code compliant. Based on research and records of recent earthquakes in Indonesia, the use of a non-code compliant confining reinforcement for concrete columns produces structures with poor seismic performance. This paper presents a study that introduces an additional element that is expected to improve the effectiveness of concrete columns confined with a non-code compliant confining reinforcement. The additional element, named a pen-binder, is used to keep the non-code compliant confining reinforcement in place. The effectiveness of this element under pure axial concentric loading was investigatedcomprehensively.The specimens tested in this study were 18 concrete columns,with a cross-section of 170 mm x 170 mm and a height of 480 mm. The main test variables were the material type of the pen-binder, the angle of the hook, and the confining reinforcement configuration.The test results indicate that adding pen-binders can effectively improve the strength and ductility of the column specimens confined with a non-code compliant confining reinforcement

Losas de concreto reforzadas con acero inoxidable de desecho Reinforced concrete slabs with stainless steel waste

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Jorge Alberto Pérez González

2008-08-01

Full Text Available Se muestran los resultados de un programa experimental que explora la reutilización de materiales de desecho industrial (específicamente láminas de acero inoxidable producto de la acuñación de moneda como refuerzo en losas de concreto. Para ello se elaboraron 23 especímenes tipo viga-losa a escala natural con dicho refuerzo a fin de determinar su comportamiento en términos de resistencia, ductilidad y formas de falla; el análisis experimental de modelos ensayados con diferentes cantidades de refuerzo muestra que en algunos casos, bajo ciertas condiciones de cuantías y colocación del mismo, es posible alcanzar capacidades de carga y formas de falla similares a las de especímenes de control con refuerzo tradicional. En base a estos resultados se concluye en la factibilidad de utilizar el material arriba descrito como refuerzo alternativo en elementos estructurales de concreto, tratando de encontrar alternativas más económicas en la construcción de vivienda popular.The results from an experimental program that explores the use of industrial waste materials (specifically sheets of stainless steel that result of the currency coinage as reinforcement for concrete slabs are presented. Twenty three full size beam-deck specimens were built in order to measure resistance, ductility and failure modes; the experimental analysis in models with reinforcement in different quantities shows that in some cases, under certain quantities and location, it is possible to reach similar load capacities and failure modes as specimens with traditional reinforcement. Based on these results, it is concluded the feasibility of using the material described above as alternative reinforcement in structural concrete elements, as an economic option in the construction of social housing.

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

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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.

Influence of reinforcement's corrosion into hyperstatic reinforced concrete beams: a probabilistic failure scenarios analysis

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G. P. PELLIZZER

Full Text Available AbstractThis work aims to study the mechanical effects of reinforcement's corrosion in hyperstatic reinforced concrete beams. The focus is the probabilistic determination of individual failure scenarios change as well as global failure change along time. The limit state functions assumed describe analytically bending and shear resistance of reinforced concrete rectangular cross sections as a function of steel and concrete resistance and section dimensions. It was incorporated empirical laws that penalize the steel yield stress and the reinforcement's area along time in addition to Fick's law, which models the chloride penetration into concrete pores. The reliability theory was applied based on Monte Carlo simulation method, which assesses each individual probability of failure. The probability of global structural failure was determined based in the concept of failure tree. The results of a hyperstatic reinforced concrete beam showed that reinforcements corrosion make change into the failure scenarios modes. Therefore, unimportant failure modes in design phase become important after corrosion start.

“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....

Fabrication of durable fluorine-free superhydrophobic polyethersulfone (PES) composite coating enhanced by assembled MMT-SiO2 nanoparticles

Science.gov (United States)

Zhang, Xiguang; Wang, Huaiyuan; Liu, Zhanjian; Zhu, Yixing; Wu, Shiqi; Wang, Chijia; Zhu, Yanji

2017-02-01

A durable fluorine-free polyethersulfone (PES) superhydrophobic composite coating with excellent wear-resistant and anti-corrosion properties has been successfully fabricated by combining sol-gel and spray technology. The robust micro/nano-structures of the prepared surface were established by introducing binary montmorillonite-silica (MMT-SiO2) assembled composite particles, which were formed by in-situ growth of SiO2 on MMT surfaces via sol-gel. Combined with the low surface energy of amino silicon oil (APDMS), the fluorine-free superhydrophoic PES coating was obtained with high water contact angle 156.1 ± 1.1° and low sliding angle 4.8 ± 0.7°. The anti-wear of the final PES/APDMS/MMT-SiO2 superhydrophobic coating can reach up to 60,100 cycles, which is outdistancing the pure PES coating (6800 cycles) and the PES/MMT/SiO2 coating prepared by simple physical mixture (18,200 cycles). The enhanced wear resistance property can be mainly attributed to the lubrication performance of APDMS and stable interface bonding force between the MMT surface and SiO2. Simultaneously, potentiodynamic polarization curves and electrochemical impedance spectroscopy exhibited the outstanding anti-corrosion property of PES/APDMS/MMT-SiO2 composite coating, with low corrosion current (1.6 × 10-10 A/cm2) and high protection efficiency (99.999%) even after 30 d immersion process. These test results show that this durable superhydrophobic PES composite coating can be hopefully to provide the possibility of industrial application.

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.

Finite element modeling of reinforced concrete beams with a hybrid combination of steel and aramid reinforcement

International Nuclear Information System (INIS)

Hawileh, R.A.

2015-01-01

Highlights: • Modeling of concrete beams reinforced steel and FRP bars. • Developed finite element models achieved good results. • The models are validated via comparison with experimental results. • Parametric studies are performed. - Abstract: Corrosion of steel bars has an adverse effect on the life-span of reinforced concrete (RC) members and is usually associated with crack development in RC beams. Fiber reinforced polymer (FRP) bars have been recently used to reinforce concrete members in flexure due to their high tensile strength and superior corrosion resistance properties. However, FRP materials are brittle in nature, thus RC beams reinforced with such materials would exhibit a less ductile behavior when compared to similar members reinforced with conventional steel reinforcement. Recently, researchers investigated the performance of concrete beams reinforced with a hybrid combination of steel and Aramid Fiber Reinforced Polymer (AFRP) reinforcement to maintain a reasonable level of ductility in such members. The function of the AFRP bars is to increase the load-carrying capacity, while the function of the steel bars is to ensure ductility of the flexural member upon yielding in tension. This paper presents a three-dimensional (3D) finite element (FE) model that predicted the load versus mid-span deflection response of tested RC beams conducted by other researchers with a hybrid combination of steel and AFRP bars. The developed FE models account for the constituent material nonlinearities and bond–slip behavior between the reinforcing bars and adjacent concrete surfaces. It was concluded that the developed models can accurately capture the behavior and predicts the load-carrying capacity of such RC members. In addition, a parametric study is conducted using the validated models to investigate the effect of AFRP bar size, FRP material type, bond–slip action, and concrete compressive strength on the performance of concrete beams when reinforced

Health monitoring of precast bridge deck panels reinforced with glass fiber reinforced polymer (GFRP) bars.

Science.gov (United States)

2012-03-01

The present research project investigates monitoring concrete precast panels for bridge decks that are reinforced with Glass Fiber Reinforced Polymer (GFRP) bars. Due to the lack of long term research on concrete members reinforced with GFRP bars, lo...

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

Directory of Open Access Journals (Sweden)

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.

Caregiver preference for reinforcement-based interventions for problem behavior maintained by positive reinforcement.

Science.gov (United States)

Gabor, Anne M; Fritz, Jennifer N; Roath, Christopher T; Rothe, Brittany R; Gourley, Denise A

2016-06-01

Social validity of behavioral interventions typically is assessed with indirect methods or by determining preferences of the individuals who receive treatment, and direct observation of caregiver preference rarely is described. In this study, preferences of 5 caregivers were determined via a concurrent-chains procedure. Caregivers were neurotypical, and children had been diagnosed with developmental disabilities and engaged in problem behavior maintained by positive reinforcement. Caregivers were taught to implement noncontingent reinforcement (NCR), differential reinforcement of alternative behavior (DRA), and differential reinforcement of other behavior (DRO), and the caregivers selected interventions to implement during sessions with the child after they had demonstrated proficiency in implementing the interventions. Three caregivers preferred DRA, 1 caregiver preferred differential reinforcement procedures, and 1 caregiver did not exhibit a preference. Direct observation of implementation in concurrent-chains procedures may allow the identification of interventions that are implemented with sufficient integrity and preferred by caregivers. © 2016 Society for the Experimental Analysis of Behavior.

Effects of reinforcer magnitude on responding under differential-reinforcement-of-low-rate schedules of rats and pigeons.

Science.gov (United States)

Doughty, Adam H; Richards, Jerry B

2002-07-01

Experiment I investigated the effects of reinforcer magnitude on differential-reinforcement-of-low-rate (DRL) schedule performance in three phases. In Phase 1, two groups of rats (n = 6 and 5) responded under a DRI. 72-s schedule with reinforcer magnitudes of either 30 or 300 microl of water. After acquisition, the water amounts were reversed for each rat. In Phase 2, the effects of the same reinforcer magnitudes on DRL 18-s schedule performance were examined across conditions. In Phase 3, each rat responded unider a DR1. 18-s schedule in which the water amotnts alternated between 30 and 300 microl daily. Throughout each phase of Experiment 1, the larger reinforcer magnitude resulted in higher response rates and lower reinforcement rates. The peak of the interresponse-time distributions was at a lower value tinder the larger reinforcer magnitude. In Experiment 2, 3 pigeons responded under a DRL 20-s schedule in which reinforcer magnitude (1-s or 6-s access to grain) varied iron session to session. Higher response rates and lower reinforcement rates occurred tinder the longer hopper duration. These results demonstrate that larger reinforcer magnitudes engender less efficient DRL schedule performance in both rats and pigeons, and when reinforcer magnitude was held constant between sessions or was varied daily. The present results are consistent with previous research demonstrating a decrease in efficiency as a function of increased reinforcer magnituide tinder procedures that require a period of time without a specified response. These findings also support the claim that DRI. schedule performance is not governed solely by a timing process.

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

The usage of carbon fiber reinforcement polymer and glass fiber reinforcement polymer for retrofit technology building

Science.gov (United States)

Tarigan, Johannes; Meka, Randi; Nursyamsi

2018-03-01

Fiber Reinforcement Polymer has been used as a material technology since the 1970s in Europe. Fiber Reinforcement Polymer can reinforce the structure externally, and used in many types of buildings like beams, columns, and slabs. It has high tensile strength. Fiber Reinforcement Polymer also has high rigidity and strength. The profile of Fiber Reinforcement Polymer is thin and light, installation is simple to conduct. One of Fiber Reinforcement Polymer material is Carbon Fiber Reinforcement Polymer and Glass Fiber Reinforcement Polymer. These materials is tested when it is installed on concrete cylinders, to obtain the comparison of compressive strength CFRP and GFRP. The dimension of concrete is diameter of 15 cm and height of 30 cm. It is amounted to 15 and divided into three groups. The test is performed until it collapsed to obtain maximum load. The results of research using CFRP and GFRP have shown the significant enhancement in compressive strength. CFRP can increase the compressive strength of 26.89%, and GFRP of 14.89%. For the comparison of two materials, CFRP is more strengthening than GFRP regarding increasing compressive strength. The usage of CFRP and GFRP can increase the loading capacity.

Micro-structure, Mechanical Properties and Dielectric Properties of Bisphenol A Allyl Compound-Bismaleimide Modified by Super-Critical Silica and Polyethersulfone Composite

Science.gov (United States)

Chen, Yufei; Wang, Botao; Li, Fangliang; Teng, Chengjun

2017-07-01

Bisphenol A allyl compound-bismaleimide (MBAE) composite modified by SCE-SiO2 and polyethersulfone (PES) resin has been prepared and researched. SCE-SiO2 was modified by super-critical ethanol and PES thermoplastic resin used as modifiers. The composite was prepared via the hot melting method. The FT-IR measurements indicated that ethanol molecular had adsorbed on the nano-SiO2 surface. SEM images showed that the composite had a multiphase structure, PES and SCE-SiO2 existed as a dispersed phase, and the interaction of the three phases affected each other, such that the bending fracture behavior transformed from brittle fracture to ductile fracture, and the modifiers of SCE-SiO2 and PES resin could improve the mechanical properties. The impact and the bending strength of the composite was 16.5 kJ/mm2 and 150.4 MPa, improved by 68.3% and 56.7% compared with those of the MBAE matrix, respectively, when the content of SCE-SiO2 was 2 wt.% and PES 5 wt.%. The dielectric constant ( ɛ) of the composites was less than 3.9 and decreased with increasing frequency, and the dielectric loss was less than 9 × 10-3 for frequencies between 102 Hz and 105 Hz. These properties could meet the requirement of insulating material.

The effect of non-contact heating (microwave irradiation) and contact heating (annealing process) on properties and performance of polyethersulfone nanofiltration membranes

International Nuclear Information System (INIS)

Mansourpanah, Y.; Madaeni, S.S.; Rahimpour, A.; Farhadian, A.

2009-01-01

In this work the effect of microwave irradiation on morphology and performance of polyethersulfone (PES) membranes was investigated. The membranes were prepared with 20 wt.% of PES by phase inversion method. N,N-dimethylformamide (DMF) and mixture of water and ethyl alcohol (90/10 vol.%) were employed as solvent and coagulant respectively. Polyvinylpirrolidone (PVP) with the concentration of 2 wt.% was selected as pore former. The effects of irradiation time (10, 30, 60, 90, 120 s) and microwave power (180, 360, 720 and 900 W) on structure and performance of membranes were studied. Increasing the irradiation time and power caused variation in permeate flux and ion rejection. Moreover, the effects of annealing processes (60, 70, 80 deg. C) were studied. Transmembrane pressure was selected around 1.5 MPa for all experiments. Scanning electron microscope (SEM) and atomic force microscope (AFM) were employed to describe the surface morphology of the prepared membranes. The effect of microwave irradiation time in different power revealed alterations in membrane surface morphology and AFM images represented that surface parameters (such as surface roughness) have been changed. The membrane exhibited moderate rejection (47%) and low permeate flux (4.5 kg/m 2 h) at 80 deg. C for NaCl solution. The SEM images indicate that the dense skin layer is formed at 80 deg. C annealing.

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

Directory of Open Access Journals (Sweden)

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

Reinforced concrete tomography

International Nuclear Information System (INIS)

Mariscotti, M.A.J.; Morixe, M.; Tarela, P.A.; Thieberger, P.

1997-01-01

In this paper we describe the technique of reinforced concrete tomography, its historical background, recent technological developments and main applications. Gamma radiation sensitive plates are imprinted with radiation going through the concrete sample under study, and then processed to reveal the presence of reinforcement and defects in the material density. The three dimensional reconstruction, or tomography, of the reinforcement out of a single gammagraphy is an original development alternative to conventional methods. Re-bar diameters and positions may be determined with an accuracy of ± 1 mm 0.5-1 cm, respectively. The non-destructive character of this technique makes it particularly attractive in cases of inhabited buildings and diagnoses of balconies. (author) [es

Prediction of reinforcement corrosion using corrosion induced cracks width in corroded reinforced concrete beams

International Nuclear Information System (INIS)

Khan, Inamullah; François, Raoul; Castel, Arnaud

2014-01-01

This paper studies the evolution of reinforcement corrosion in comparison to corrosion crack width in a highly corroded reinforced concrete beam. Cracking and corrosion maps of the beam were drawn and steel reinforcement was recovered from the beam to observe the corrosion pattern and to measure the loss of mass of steel reinforcement. Maximum steel cross-section loss of the main reinforcement and average steel cross-section loss between stirrups were plotted against the crack width. The experimental results were compared with existing models proposed by Rodriguez et al., Vidal et al. and Zhang et al. Time prediction models for a given opening threshold are also compared to experimental results. Steel cross-section loss for stirrups was also measured and was plotted against the crack width. It was observed that steel cross-section loss in the stirrups had no relationship with the crack width of longitudinal corrosion cracks. -- Highlights: •Relationship between crack and corrosion of reinforcement was investigated. •Corrosion results of natural process and then corresponds to in-situ conditions. •Comparison with time predicting model is provided. •Prediction of load-bearing capacity from crack pattern was studied

Study of the internal confinement of concrete reinforced (in civil engineering) with woven reinforcement

Science.gov (United States)

Dalal, M.; Goumairi, O.; El Malik, A.

2017-10-01

Concrete is generally the most used material in the field of construction. Despite its extensive use in structures, it represents some drawbacks related to its properties including its low tensile strength and low ductility. To solve this problem, the use of steel reinforcement in concrete structures is possible. Another possibility is the introduction of different types of continuous fibre / staple in the concrete, such as steel fibres or synthetic fibres, to obtain ″Concretes bundles″. Many types of fibre concrete, which have been developed and for many of them, the gain provided by the fibre was rather low and no significant improvement in tensile strength was really reaching. By cons, the ductility was higher than that of ordinary concrete. The objective of this study is to examine concrete reinforcement by inserting reinforcements woven polyester. These are either woven bidirectional (2D) or three-dimensional woven (3D). So we will report the properties of each type of reinforcement and the influence of the method of weaving on the strength reinforcements and on the strength of concrete in which they are incorporated. Such influence should contribute to improving the sustainability and enhancement of reinforcement

The Reinforcing Event (RE) Menu

Science.gov (United States)

Addison, Roger M.; Homme, Lloyd E.

1973-01-01

A motivational system, the Contingency Management System, uses contracts in which some amount of defined task behavior is demanded for some interval of reinforcing event. The Reinforcing Event Menu, a list of high probability reinforcing behaviors, is used in the system as a prompting device for the learner and as an aid for the administrator in…

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

Directory of Open Access Journals (Sweden)

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.

Fouling behavior of poly(ether)sulfone ultrafiltration membrane during concentration of whey proteins: Effect of hydrophilic modification using atmospheric pressure argon jet plasma.

Science.gov (United States)

Damar Huner, Irem; Gulec, Haci Ali

2017-12-01

The aim of the study was to investigate the effects of hydrophilic surface modification via atmospheric pressure jet plasma (ApJPls) on the fouling propensity of polyethersulfone (PES) ultrafiltration (UF) membranes during concentration of whey proteins. The distance from nozzle to substrate surface of 30mm and the exposure period of 5 times were determined as the most effective parameters enabling an increase in ΔG iwi value of the plain membrane from (-) 14.92±0.89mJ/m 2 to (+) 17.57±0.67mJ/m 2 . Maximum hydrophilicity and minimum surface roughness achieved by argon plasma action resulted in better antifouling behavior, while the hydraulic permeability and the initial permeate flux were decreased sharply due to the plasma-induced surface cross-linking. A quite steady state flux was obtained throughout the UF with the ApJPls modified PES membrane. The contribution of R frev to R t , which was 94% for the UF through the plain membrane, decreased to 43% after the plasma treatment. The overall results of this study highlighted the ApJPls modification decreased the fouling propensity of PES membrane without affecting the original protein rejection capability and improved the recovery of initial permeate flux after chemical cleaning. Copyright © 2017 Elsevier B.V. All rights reserved.

Steel fiber reinforced concrete

International Nuclear Information System (INIS)

Baloch, S.U.

2005-01-01

Steel-Fiber Reinforced Concrete is constructed by adding short fibers of small cross-sectional size .to the fresh concrete. These fibers reinforce the concrete in all directions, as they are randomly oriented. The improved mechanical properties of concrete include ductility, impact-resistance, compressive, tensile and flexural strength and abrasion-resistance. These uniqlte properties of the fiber- reinforcement can be exploited to great advantage in concrete structural members containing both conventional bar-reinforcement and steel fibers. The improvements in mechanical properties of cementitious materials resulting from steel-fiber reinforcement depend on the type, geometry, volume fraction and material-properties of fibers, the matrix mix proportions and the fiber-matrix interfacial bond characteristics. Effects of steel fibers on the mechanical properties of concrete have been investigated in this paper through a comprehensive testing-programme, by varying the fiber volume fraction and the aspect-ratio (Lid) of fibers. Significant improvements are observed in compressive, tensile, flexural strength and impact-resistance of concrete, accompanied by marked improvement in ductility. optimum fiber-volume fraction and aspect-ratio of steel fibers is identified. Test results are analyzed in details and relevant conclusions drawn. The research is finally concluded with future research needs. (author)

Corrosion of reinforcement bars in steel ibre reinforced concrete structures

DEFF Research Database (Denmark)

Solgaard, Anders Ole Stubbe

and the influence of steel fibres on initiation and propagation of cracks in concrete. Moreover, the impact of fibres on corrosion-induced cover cracking was covered. The impact of steel fibres on propagation of reinforcement corrosion was investigated through studies of their impact on the electrical resistivity...... of concrete, which is known to affect the corrosion process of embedded reinforcement. The work concerning the impact of steel fibres on initiation and propagation of cracks was linked to corrosion initiation and propagation of embedded reinforcement bars via additional studies. Cracks in the concrete cover...... are known to alter the ingress rate of depassivating substances and thereby influence the corrosion process. The Ph.D. study covered numerical as well as experimental studies. Electrochemically passive steel fibres are electrically isolating thus not changing the electrical resistivity of concrete, whereas...

Algorithms for Reinforcement Learning

CERN Document Server

Szepesvari, Csaba

2010-01-01

Reinforcement learning is a learning paradigm concerned with learning to control a system so as to maximize a numerical performance measure that expresses a long-term objective. What distinguishes reinforcement learning from supervised learning is that only partial feedback is given to the learner about the learner's predictions. Further, the predictions may have long term effects through influencing the future state of the controlled system. Thus, time plays a special role. The goal in reinforcement learning is to develop efficient learning algorithms, as well as to understand the algorithms'

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

Directory of Open Access Journals (Sweden)

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

Directory of Open Access Journals (Sweden)

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.

Continuous Reinforced Concrete Beams

DEFF Research Database (Denmark)

Hoang, Cao Linh; Nielsen, Mogens Peter

1996-01-01

This report deals with stress and stiffness estimates of continuous reinforced concrete beams with different stiffnesses for negative and positive moments e.g. corresponding to different reinforcement areas in top and bottom. Such conditions are often met in practice.The moment distribution...

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.

Modelling reinforcement corrosion in concrete

DEFF Research Database (Denmark)

Michel, Alexander; Geiker, Mette Rica; Stang, Henrik

2012-01-01

A physio-chemical model for the simulation of reinforcement corrosion in concrete struc-tures was developed. The model allows for simulation of initiation and subsequent propaga-tion of reinforcement corrosion. Corrosion is assumed to be initiated once a defined critical chloride threshold......, a numerical example is pre-sented, that illustrates the formation of corrosion cells as well as propagation of corrosion in a reinforced concrete structure....

The Reinforcement Learning Competition 2014

OpenAIRE

Dimitrakakis, Christos; Li, Guangliang; Tziortziotis, Nikoalos

2014-01-01

Reinforcement learning is one of the most general problems in artificial intelligence. It has been used to model problems in automated experiment design, control, economics, game playing, scheduling and telecommunications. The aim of the reinforcement learning competition is to encourage the development of very general learning agents for arbitrary reinforcement learning problems and to provide a test-bed for the unbiased evaluation of algorithms.

Origins of food reinforcement in infants12345

Science.gov (United States)

Kong, Kai Ling; Feda, Denise M; Eiden, Rina D; Epstein, Leonard H

2015-01-01

Background: Rapid weight gain in infancy is associated with a higher risk of obesity in children and adults. A high relative reinforcing value of food is cross-sectionally related to obesity; lean children find nonfood alternatives more reinforcing than do overweight/obese children. However, to our knowledge, there is no research on how and when food reinforcement develops. Objective: This study was designed to assess whether the reinforcing value of food and nonfood alternatives could be tested in 9- to 18-mo-old infants and whether the reinforcing value of food and nonfood alternatives is differentially related to infant weight status. Design: Reinforcing values were assessed by using absolute progressive ratio schedules of reinforcement, with presentation of food and nonfood alternatives counterbalanced in 2 separate studies. Two nonfood reinforcers [Baby Einstein–Baby MacDonald shows (study 1, n = 27) or bubbles (study 2, n = 30)] were tested against the baby’s favorite food. Food reinforcing ratio (FRR) was quantified by measuring the reinforcing value of food (Food Pmax) in proportion to the total reinforcing value of food and a nonfood alternative (DVD Pmax or BUB Pmax). Results: Greater weight-for-length z score was associated with a greater FRR of a favorite food in study 1 (FRR-DVD) (r = 0.60, P positively associated with FRR-DVD (r = 0.57, P = 0.009) and FRR-BUB (r = 0.37, P = 0.047). Conclusions: Our newly developed paradigm, which tested 2 different nonfood alternatives, demonstrated that lean infants find nonfood alternatives more reinforcing than do overweight/obese infants. This observation suggests that strengthening the alternative reinforcers may have a protective effect against childhood obesity. This research was registered at clinicaltrials.gov as NCT02229552. PMID:25733636

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

Directory of Open Access Journals (Sweden)

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

Directory of Open Access Journals (Sweden)

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.

Effect of hybrid fiber reinforcement on the cracking process in fiber reinforced cementitious composites

DEFF Research Database (Denmark)

Pereira, Eduardo B.; Fischer, Gregor; Barros, Joaquim A.O.

2012-01-01

The simultaneous use of different types of fibers as reinforcement in cementitious matrix composites is typically motivated by the underlying principle of a multi-scale nature of the cracking processes in fiber reinforced cementitious composites. It has been hypothesized that while undergoing...... tensile deformations in the composite, the fibers with different geometrical and mechanical properties restrain the propagation and further development of cracking at different scales from the micro- to the macro-scale. The optimized design of the fiber reinforcing systems requires the objective...... materials is carried out by assessing directly their tensile stress-crack opening behavior. The efficiency of hybrid fiber reinforcements and the multi-scale nature of cracking processes are discussed based on the experimental results obtained, as well as the micro-mechanisms underlying the contribution...

Robust outer-selective thin-film composite polyethersulfone hollow fiber membranes with low reverse salt flux for renewable salinity-gradient energy generation

KAUST Repository

Cheng, Zhen Lei; Li, Xue; Liu, Ying Da; Chung, Neal Tai-Shung

2016-01-01

This study reports outer-selective thin-film composite (TFC) hollow fiber membranes with extremely low reverse salt fluxes and robustness for harvesting salinity-gradient energy from pressure retarded osmosis (PRO) processes. Almost defect-free polyamide layers with impressive low salt permeabilities were synthesized on top of robust polyethersulfone porous supports. The newly developed TFC-II membrane shows a maximum power density of 7.81 W m−2 using 1 M NaCl and DI water as feeds at 20 bar. Reproducible data obtained in the 2nd and 3rd runs confirm its stability under high hydraulic pressure differences. Comparing to other PRO membranes reported in the literature, the newly developed membrane exhibits not only the smallest slope between water flux decline and ΔPΔP increase but also the lowest ratio of reverse salt flux to water flux. Thus, the effective osmotic driving force could be well maintained even under high pressure operations. For the first time, the effect of feed pressure buildup induced by feed flowrate was evaluated towards PRO performance. A slight increment in feed pressure buildup was found to be beneficial to water flux and power density up to 10.06 W m−2 without comprising the reverse salt flux. We believe this study may open up new perspectives on outer-selective PRO hollow fiber membranes and provide useful insights to understand and design next-generation outer-selective TFC hollow fiber membranes for osmotic power generation.

Robust outer-selective thin-film composite polyethersulfone hollow fiber membranes with low reverse salt flux for renewable salinity-gradient energy generation

KAUST Repository

Cheng, Zhen Lei

2016-01-08

This study reports outer-selective thin-film composite (TFC) hollow fiber membranes with extremely low reverse salt fluxes and robustness for harvesting salinity-gradient energy from pressure retarded osmosis (PRO) processes. Almost defect-free polyamide layers with impressive low salt permeabilities were synthesized on top of robust polyethersulfone porous supports. The newly developed TFC-II membrane shows a maximum power density of 7.81 W m−2 using 1 M NaCl and DI water as feeds at 20 bar. Reproducible data obtained in the 2nd and 3rd runs confirm its stability under high hydraulic pressure differences. Comparing to other PRO membranes reported in the literature, the newly developed membrane exhibits not only the smallest slope between water flux decline and ΔPΔP increase but also the lowest ratio of reverse salt flux to water flux. Thus, the effective osmotic driving force could be well maintained even under high pressure operations. For the first time, the effect of feed pressure buildup induced by feed flowrate was evaluated towards PRO performance. A slight increment in feed pressure buildup was found to be beneficial to water flux and power density up to 10.06 W m−2 without comprising the reverse salt flux. We believe this study may open up new perspectives on outer-selective PRO hollow fiber membranes and provide useful insights to understand and design next-generation outer-selective TFC hollow fiber membranes for osmotic power generation.

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

Seismic Retrofitting: Reinforced Concrete (RC shear wall versus Reinforcement of RC element by Carbon Fiber Reinforced Polymer (CFRP using PUSHOVER analysis

Directory of Open Access Journals (Sweden)

Yahya RIYAD

2016-12-01

Full Text Available Seismic retrofitting of constructions vulnerable to earthquakes is a current problem of great political and social relevance. During the last sixty years, moderate to severe earthquakes have occurred in Morocco (specifically in Agadir 1960 and Hoceima 2004. Such events have clearly shown the vulnerability of the building stock in particular and of the built environment in general. Hence, it is very much essential to retrofit the vulnerable building to cope up for the next damaging earthquake. In this paper, the focus will be on a comparative study between two techniques of seismic retrofitting, the first one is a reinforcement using carbon fiber reinforced polymer (CFRP applied to RC elements by bonding , and the second one is a reinforcement with a shear wall. For this study, we will use a non-linear static analysis -also known as Pushover analysis - on a reinforced concrete structure consisting of beams and columns, and composed from eight storey with a gross area of 240 m², designed conforming to the Moroccan Seismic code[1].

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

Development of a living membrane comprising a functional human renal proximal tubule cell monolayer on polyethersulfone polymeric membrane.

Science.gov (United States)

Schophuizen, Carolien M S; De Napoli, Ilaria E; Jansen, Jitske; Teixeira, Sandra; Wilmer, Martijn J; Hoenderop, Joost G J; Van den Heuvel, Lambert P W; Masereeuw, Rosalinde; Stamatialis, Dimitrios

2015-03-01

The need for improved renal replacement therapies has stimulated innovative research for the development of a cell-based renal assist device. A key requirement for such a device is the formation of a "living membrane", consisting of a tight kidney cell monolayer with preserved functional organic ion transporters on a suitable artificial membrane surface. In this work, we applied a unique conditionally immortalized proximal tubule epithelial cell (ciPTEC) line with an optimized coating strategy on polyethersulfone (PES) membranes to develop a living membrane with a functional proximal tubule epithelial cell layer. PES membranes were coated with combinations of 3,4-dihydroxy-l-phenylalanine and human collagen IV (Coll IV). The optimal coating time and concentrations were determined to achieve retention of vital blood components while preserving high water transport and optimal ciPTEC adhesion. The ciPTEC monolayers obtained were examined through immunocytochemistry to detect zona occludens 1 tight junction proteins. Reproducible monolayers were formed when using a combination of 2 mg ml(-1) 3,4-dihydroxy-l-phenylalanine (4 min coating, 1h dissolution) and 25 μg ml(-1) Coll IV (4 min coating). The successful transport of (14)C-creatinine through the developed living membrane system was used as an indication for organic cation transporter functionality. The addition of metformin or cimetidine significantly reduced the creatinine transepithelial flux, indicating active creatinine uptake in ciPTECs, most likely mediated by the organic cation transporter, OCT2 (SLC22A2). In conclusion, this study shows the successful development of a living membrane consisting of a reproducible ciPTEC monolayer on PES membranes, an important step towards the development of a bioartificial kidney. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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...

FOAM CONCRETE REINFORCEMENT BY BASALT FIBRES

Directory of Open Access Journals (Sweden)

Zhukov Aleksey Dmitrievich

2012-10-01

Full Text Available The authors demonstrate that the foam concrete performance can be improved by dispersed reinforcement, including methods that involve basalt fibres. They address the results of the foam concrete modeling technology and assess the importance of technology-related parameters. Reinforcement efficiency criteria are also provided in the article. Dispersed reinforcement improves the plasticity of the concrete mix and reduces the settlement crack formation rate. Conventional reinforcement that involves metal laths and rods demonstrates its limited application in the production of concrete used for thermal insulation and structural purposes. Dispersed reinforcement is preferable. This technology contemplates the infusion of fibres into porous mixes. Metal, polymeric, basalt and glass fibres are used as reinforcing components. It has been identified that products reinforced by polypropylene fibres demonstrate substantial abradability and deformability rates even under the influence of minor tensile stresses due to the low adhesion strength of polypropylene in the cement matrix. The objective of the research was to develop the type of polypropylene of D500 grade that would demonstrate the operating properties similar to those of Hebel and Ytong polypropylenes. Dispersed reinforcement was performed by the basalt fibre. This project contemplates an autoclave-free technology to optimize the consumption of electricity. Dispersed reinforcement is aimed at the reduction of the block settlement in the course of hardening at early stages of their operation, the improvement of their strength and other operating properties. Reduction in the humidity rate of the mix is based on the plasticizing properties of fibres, as well as the application of the dry mineralization method. Selection of optimal parameters of the process-related technology was performed with the help of G-BAT-2011 Software, developed at Moscow State University of Civil Engineering. The authors also

PLACAS CERÂMICAS - UMA INTRODUÇÃO

Directory of Open Access Journals (Sweden)

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.

The possibility of using high strength reinforced concrete

International Nuclear Information System (INIS)

Miura, Nobuaki

1991-01-01

There is recently much research about and developments in reinforced concrete using high strength concrete and reinforcement. As a result, some high-rise buildings and nuclear buildings have been constructed with such concrete. Reinforced concrete will be stronger in the future, but there is a limit to its strength defined by the character of the materials and also by the character of the reinforced concrete members made of the concrete and reinforcement. This report describes the merits and demerits of using high strength reinforced concrete. (author)

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

Directory of Open Access Journals (Sweden)

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.

Reinforced concrete wall under hydrogen detonation

International Nuclear Information System (INIS)

Saarenheimo, A.

2000-11-01

The structural integrity of a reinforced concrete wall in the BWR reactor building under hydrogen detonation conditions has been analysed. Of particular interest is whether the containment integrity can be jeopardised by an external hydrogen detonation. The load carrying capacity of a reinforced concrete wall was studied. The detonation pressure loads were estimated with computerised hand calculations assuming a direct initiation of detonation and applying the strong explosion theory. The results can be considered as rough and conservative estimates for the first shock pressure impact induced by a reflecting detonation wave. Structural integrity may be endangered due to slow pressurisation or dynamic impulse loads associated with local detonations. The static pressure following the passage of a shock front may be relatively high, thus this static or slowly decreasing pressure after a detonation may damage the structure severely. The mitigating effects of the opening of a door on pressure history and structural response were also studied. The non-linear behaviour of the wall was studied under detonations corresponding a detonable hydrogen mass of 0.5 kg and 1.428 kg. Non-linear finite element analyses of the reinforced concrete structure were carried out by the ABAQUS/Explicit program. The reinforcement and its non-linear material behaviour and the tensile cracking of concrete were modelled. Reinforcement was defined as layers of uniformly spaced reinforcing bars in shell elements. In these studies the surrounding structures of the non-linearly modelled reinforced concrete wall were modelled using idealised boundary conditions. Especially concrete cracking and yielding of the reinforcement was monitored during the numerical simulation. (au)

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.

On the weld strength of in situ tape placed reinforcements on weave reinforced structures

NARCIS (Netherlands)

Grouve, Wouter Johannes Bernardus; Warnet, Laurent; Rietman, Bert; Akkerman, Remko

2012-01-01

Unidirectionally reinforced thermoplastic tapes were welded onto woven fabric reinforced laminates using a laser assisted tape placement process. A mandrel peel setup was used to quantify the interfacial fracture toughness between the tape and the laminate as a measure for weld strength. The tape

Reinforcement Learning State-of-the-Art

CERN Document Server

Wiering, Marco

2012-01-01

Reinforcement learning encompasses both a science of adaptive behavior of rational beings in uncertain environments and a computational methodology for finding optimal behaviors for challenging problems in control, optimization and adaptive behavior of intelligent agents. As a field, reinforcement learning has progressed tremendously in the past decade. The main goal of this book is to present an up-to-date series of survey articles on the main contemporary sub-fields of reinforcement learning. This includes surveys on partially observable environments, hierarchical task decompositions, relational knowledge representation and predictive state representations. Furthermore, topics such as transfer, evolutionary methods and continuous spaces in reinforcement learning are surveyed. In addition, several chapters review reinforcement learning methods in robotics, in games, and in computational neuroscience. In total seventeen different subfields are presented by mostly young experts in those areas, and together the...

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

Directory of Open Access Journals (Sweden)

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.

Facilitating tolerance of delayed reinforcement during functional communication training.

Science.gov (United States)

Fisher, W W; Thompson, R H; Hagopian, L P; Bowman, L G; Krug, A

2000-01-01

Few clinical investigations have addressed the problem of delayed reinforcement. In this investigation, three individuals whose destructive behavior was maintained by positive reinforcement were treated using functional communication training (FCT) with extinction (EXT). Next, procedures used in the basic literature on delayed reinforcement and self-control (reinforcer delay fading, punishment of impulsive responding, and provision of an alternative activity during reinforcer delay) were used to teach participants to tolerate delayed reinforcement. With the first case, reinforcer delay fading alone was effective at maintaining low rates of destructive behavior while introducing delayed reinforcement. In the second case, the addition of a punishment component reduced destructive behavior to near-zero levels and facilitated reinforcer delay fading. With the third case, reinforcer delay fading was associated with increases in masturbation and head rolling, but prompting and praising the individual for completing work during the delay interval reduced all problem behaviors and facilitated reinforcer delay fading.

Reinforced Conductive Polyaniline-Paper Composites

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Jinhua Yan

2015-05-01

Full Text Available A method for direct aniline interfacial polymerization on polyamideamine-epichlorohydrin (PAE-reinforced paper substrate is introduced in this paper. Cellulose-based papers with and without reinforcement were considered. The polyaniline (PANI-paper composites had surface resistivity lower than 100 Ω/sq after more than 3 polymerizations. Their mechanical strength and thermal stability were analyzed by tensile tests and thermogravimetric analysis (TGA. Fourier transform infrared (FTIR results revealed that there was strong interaction between NH groups in aniline monomers and OH groups in fibers, which did not disappear until after 3 polymerizations. Scanning electron microscopy (SEM and field emission (FE SEM images showed morphological differences between composites using reinforced and untreated base papers. Conductive composites made with PAE-reinforced base paper had both good thermal stability and good mechanical strength, with high conductivity and a smaller PANI amount.

Superelastic SMA–FRP composite reinforcement for concrete structures

International Nuclear Information System (INIS)

Wierschem, Nicholas; Andrawes, Bassem

2010-01-01

For many years there has been interest in using fiber-reinforced polymers (FRPs) as reinforcement in concrete structures. Unfortunately, due to their linear elastic behavior, FRP reinforcing bars are never considered for structural damping or dynamic applications. With the aim of improving the ductility and damping capability of concrete structures reinforced with FRP reinforcement, this paper studies the application of SMA–FRP, a relatively novel type of composite reinforced with superelastic shape memory alloy (SMA) wires. The cyclic tensile behavior of SMA–FRP composites are studied experimentally and analytically. Tests of SMA–FRP composite coupons are conducted to determine their constitutive behavior. The experimental results are used to develop and calibrate a uniaxial SMA–FRP analytical model. Parametric and case studies are performed to determine the efficacy of the SMA–FRP reinforcement in concrete structures and the key factors governing its behavior. The results show significant potential for SMA–FRP reinforcement to improve the ductility and damping of concrete structures while still maintaining its elastic characteristic, typical of FRP reinforcement

Positive behavioral contrast across food and alcohol reinforcers.

OpenAIRE

McSweeney, F K; Melville, C L; Higa, J

1988-01-01

The present study examined behavioral contrast during concurrent and multiple schedules that provided food and alcohol reinforcers. Concurrent-schedule contrast occurred in the responding reinforced by food when alcohol reinforcers were removed. It also occurred in the responding reinforced by alcohol when food was removed. Multiple-schedule contrast appeared for food when alcohol reinforcers were removed, but not for alcohol when food was removed. These results show that behavioral contrast ...

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.

Learning to trade via direct reinforcement.

Science.gov (United States)

Moody, J; Saffell, M

2001-01-01

We present methods for optimizing portfolios, asset allocations, and trading systems based on direct reinforcement (DR). In this approach, investment decision-making is viewed as a stochastic control problem, and strategies are discovered directly. We present an adaptive algorithm called recurrent reinforcement learning (RRL) for discovering investment policies. The need to build forecasting models is eliminated, and better trading performance is obtained. The direct reinforcement approach differs from dynamic programming and reinforcement algorithms such as TD-learning and Q-learning, which attempt to estimate a value function for the control problem. We find that the RRL direct reinforcement framework enables a simpler problem representation, avoids Bellman's curse of dimensionality and offers compelling advantages in efficiency. We demonstrate how direct reinforcement can be used to optimize risk-adjusted investment returns (including the differential Sharpe ratio), while accounting for the effects of transaction costs. In extensive simulation work using real financial data, we find that our approach based on RRL produces better trading strategies than systems utilizing Q-learning (a value function method). Real-world applications include an intra-daily currency trader and a monthly asset allocation system for the S&P 500 Stock Index and T-Bills.

Enhancement of shear strength and ductility for reinforced concrete wide beams due to web reinforcement

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M. Said

2013-12-01

Full Text Available The shear behavior of reinforced concrete wide beams was investigated. The experimental program consisted of nine beams of 29 MPa concrete strength tested with a shear span-depth ratio equal to 3.0. One of the tested beams had no web reinforcement as a control specimen. The flexure mode of failure was secured for all of the specimens to allow for shear mode of failure. The key parameters covered in this investigation are the effect of the existence, spacing, amount and yield stress of the vertical stirrups on the shear capacity and ductility of the tested wide beams. The study shows that the contribution of web reinforcement to the shear capacity is significant and directly proportional to the amount and spacing of the shear reinforcement. The increase in the shear capacity ranged from 32% to 132% for the range of the tested beams compared with the control beam. High grade steel was more effective in the contribution of the shear strength of wide beams. Also, test results demonstrate that the shear reinforcement significantly enhances the ductility of the wide beams. In addition, shear resistances at failure recorded in this study are compared to the analytical strengths calculated according to the current Egyptian Code and the available international codes. The current study highlights the need to include the contribution of shear reinforcement in the Egyptian Code requirements for shear capacity of wide beams.

Fibre Reinforced Polymer Composites as Internal and External Reinforcements for Building Elements

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Cătălin Banu

2008-01-01

Full Text Available During the latest decades fibre reinforced polymer (FRP composite materials have proven valuable properties and suitable to be used in construction of new buildings and in upgrading the existing ones. These materials have covered the road from research laboratory and demonstration projects to implementation in actual structures. Nowadays the civil and structural engineering communities are about to commence the stage in which the use of FRP composites is becoming a routine similar to that of traditional material such as concrete, masonry and wood. Two main issues are presented in this paper, the use of FRP composite materials for new structural members (internal reinforcements and strengthening of existing members (externally bonded reinforcements. The advantages and disadvantages as well as the problems and constraints associated with both issues are discussed in detail mainly related to concrete members.

Strength Characteristics of Reinforced Sandy Soil

OpenAIRE

S. N. Bannikov; Mahamed Al Fayez

2005-01-01

Laboratory tests on determination of reinforced sandy soil strength characteristics (angle of internal friction, specific cohesive force) have been carried out with the help of a specially designed instrument and proposed methodology. Analysis of the obtained results has revealed that cohesive forces are brought about in reinforced sandy soil and an angle of internal soil friction becomes larger in comparison with non-reinforced soil.

Analytical, Numerical and Experimental Examination of Reinforced Composites Beams Covered with Carbon Fiber Reinforced Plastic

Science.gov (United States)

Kasimzade, A. A.; Tuhta, S.

2012-03-01

In the article, analytical, numerical (Finite Element Method) and experimental investigation results of beam that was strengthened with fiber reinforced plastic-FRP composite has been given as comparative, the effect of FRP wrapping number to the maximum load and moment capacity has been evaluated depending on this results. Carbon FRP qualitative dependences have been occurred between wrapping number and beam load and moment capacity for repair-strengthen the reinforced concrete beams with carbon fiber. Shown possibilities of application traditional known analysis programs, for the analysis of Carbon Fiber Reinforced Plastic (CFRP) strengthened structures.

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.

Producing Durable Continuously Reinforced Concrete Pavement using Glass-ceramic Coated Reinforcing Steel

Science.gov (United States)

2010-02-01

reinforcement if the enamel is broken  Embedded cement grains hydrate if enamel is cracked to self-heal with the formation of calcium silicate hydrate Goal...Reinforced Concrete Pavement The 600% volume change in the iron to iron oxide formation put the concrete in tension and it cracks an spalls BUILDING...corrodes prematurely and delaminates the pavement  Moisture and chlorides can move through the natural porosity of concrete and the cracks in the

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

Directory of Open Access Journals (Sweden)

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.

Constitutive model for reinforced concrete

NARCIS (Netherlands)

Feenstra, P.H.; Borst, de R.

1995-01-01

A numerical model is proposed for reinforced-concrete behavior that combines the commonly accepted ideas from modeling plain concrete, reinforcement, and interaction behavior in a consistent manner. The behavior of plain concrete is govern by fracture-energy-level-based formulation both in tension

Tangible Reinforcers: Bonuses or Bribes?

Science.gov (United States)

O'Leary, K. Daniel; And Others

1972-01-01

Objections to the use of tangible reinforcers, such as prizes, candy, cigarettes, and money, are discussed. Treatment programs using tangible reinforcers are recommended as powerful modifers of behavior to be implemented only after less powerful means of modification have been tried. (Author)

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.

TEACHING SELF-CONTROL WITH QUALITATIVELY DIFFERENT REINFORCERS

OpenAIRE

Passage, Michael; Tincani, Matt; Hantula, Donald A.

2012-01-01

This study examined the effectiveness of using qualitatively different reinforcers to teach self-control to an adolescent boy who had been diagnosed with an intellectual disability. First, he was instructed to engage in an activity without programmed reinforcement. Next, he was instructed to engage in the activity under a two-choice fixed-duration schedule of reinforcement. Finally, he was exposed to self-control training, during which the delay to a more preferred reinforcer was initially sh...

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

Directory of Open Access Journals (Sweden)

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

Directory of Open Access Journals (Sweden)

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.

PARTIAL REINFORCEMENT (ACQUISITION) EFFECTS WITHIN SUBJECTS.

Science.gov (United States)

AMSEL, A; MACKINNON, J R; RASHOTTE, M E; SURRIDGE, C T

1964-03-01

Acquisition performance of 22 rats in a straight alley runway was examined. The animals were subjected to partial reinforcement when the alley was black (B+/-) and continuous reinforcement when it was white (W+). The results indicated (a) higher terminal performance, for partial as against continuous reinforcement conditions, for starting-time and running-time measures, and (b) lower terminal performance under partial conditions for a goal-entry-time measure. These results confirm within subjects an effect previously demonstrated, in the runway, only in between-groups tests, where one group is run under partial reinforcement and a separate group is run under continuous reinforcement in the presence of the same external stimuli. Differences between the runway situation, employing a discrete-trial procedure and performance measures at three points in the response chain, and the Skinner box situation, used in its free-operant mode with a single performance measure, are discussed in relation to the present findings.

Reinforcement Learning in Repeated Portfolio Decisions

OpenAIRE

Diao, Linan; Rieskamp, Jörg

2011-01-01

How do people make investment decisions when they receive outcome feedback? We examined how well the standard mean-variance model and two reinforcement models predict people's portfolio decisions. The basic reinforcement model predicts a learning process that relies solely on the portfolio's overall return, whereas the proposed extended reinforcement model also takes the risk and covariance of the investments into account. The experimental results illustrate that people reacted sensitively to...

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)

Responding for sucrose and wheel-running reinforcement: effects of sucrose concentration and wheel-running reinforcer duration.

Science.gov (United States)

Belke, Terry W; Hancock, Stephanie D

2003-03-01

Six male albino rats were placed in running wheels and exposed to a fixed-interval 30-s schedule of lever pressing that produced either a drop of sucrose solution or the opportunity to run for a fixed duration as reinforcers. Each reinforcer type was signaled by a different stimulus. In Experiment 1, the duration of running was held constant at 15 s while the concentration of sucrose solution was varied across values of 0, 2.5. 5, 10, and 15%. As concentration decreased, postreinforcement pause duration increased and local rates decreased in the presence of the stimulus signaling sucrose. Consequently, the difference between responding in the presence of stimuli signaling wheel-running and sucrose reinforcers diminished, and at 2.5%, response functions for the two reinforcers were similar. In Experiment 2, the concentration of sucrose solution was held constant at 15% while the duration of the opportunity to run was first varied across values of 15, 45, and 90 s then subsequently across values of 5, 10, and 15 s. As run duration increased, postreinforcement pause duration in the presence of the wheel-running stimulus increased and local rates increased then decreased. In summary, inhibitory aftereffects of previous reinforcers occurred when both sucrose concentration and run duration varied; changes in responding were attributable to changes in the excitatory value of the stimuli signaling the two reinforcers.

Rational and Mechanistic Perspectives on Reinforcement Learning

Science.gov (United States)

Chater, Nick

2009-01-01

This special issue describes important recent developments in applying reinforcement learning models to capture neural and cognitive function. But reinforcement learning, as a theoretical framework, can apply at two very different levels of description: "mechanistic" and "rational." Reinforcement learning is often viewed in mechanistic terms--as…

Conditioned Reinforcement Value and Resistance to Change

Science.gov (United States)

Shahan, Timothy A.; Podlesnik, Christopher A.

2008-01-01

Three experiments examined the effects of conditioned reinforcement value and primary reinforcement rate on resistance to change using a multiple schedule of observing-response procedures with pigeons. In the absence of observing responses in both components, unsignaled periods of variable-interval (VI) schedule food reinforcement alternated with…

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.

Glass FRP reinforcement in rehabilitation of concrete marine infrastructure

International Nuclear Information System (INIS)

Newhook, John P.

2006-01-01

Fiber reinforced polymer (FRP) reinforcements for concrete structures are gaining wide acceptance as a suitable alternative to steel reinforcements. The primary advantage is that they do not suffer corrosion and hence they promise to be more durable in environments where steel reinforced concrete has a limited life span. Concrete wharves and jetties are examples of structures subjected to such harsh environments and represent the general class of marine infrastructure in which glass FRP (GFRP) reinforcement should be used for improved durability and service life. General design considerations which make glass FRP suitable for use in marine concrete rehabilitation projects are discussed. A case study of recent wharf rehabilitation project in Canada is used to reinforce these considerations. The structure consisted of a GFRP reinforced concrete deck panel and steel - GFRP hybrid reinforced concrete pile cap. A design methodology is developed for the hybrid reinforcement design and verified through testing. The results of a field monitoring program are used to establish the satisfactory field performance of the GFRP reinforcement. The design concepts presented in the paper are applicable to many concrete marine components and other structures where steel reinforcement corrosion is a problem. (author)

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

Multi-physics corrosion modeling for sustainability assessment of steel reinforced high performance fiber reinforced cementitious composites

DEFF Research Database (Denmark)

Lepech, M.; Michel, Alexander; Geiker, Mette

2016-01-01

and widespread depassivation, are the mechanism behind experimental results of HPFRCC steel corrosion studies found in the literature. Such results provide an indication of the fundamental mechanisms by which steel reinforced HPFRCC materials may be more durable than traditional reinforced concrete and other......Using a newly developed multi-physics transport, corrosion, and cracking model, which models these phenomena as a coupled physiochemical processes, the role of HPFRCC crack control and formation in regulating steel reinforcement corrosion is investigated. This model describes transport of water...... and chemical species, the electric potential distribution in the HPFRCC, the electrochemical propagation of steel corrosion, and the role of microcracks in the HPFRCC material. Numerical results show that the reduction in anode and cathode size on the reinforcing steel surface, due to multiple crack formation...

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...

The critical dimensions of the response-reinforcer contingency.

Science.gov (United States)

Williams, B A.

2001-05-03

Two major dimensions of any contingency of reinforcement are the temporal relation between a response and its reinforcer, and the relative frequency of the reinforcer given the response versus when the response has not occurred. Previous data demonstrate that time, per se, is not sufficient to explain the effects of delay-of-reinforcement procedures; needed in addition is some account of the events occurring in the delay interval. Moreover, the effects of the same absolute time values vary greatly across situations, such that any notion of a standard delay-of-reinforcement gradient is simplistic. The effects of reinforcers occurring in the absence of a response depend critically upon the stimulus conditions paired with those reinforcers, in much the same manner as has been shown with Pavlovian contingency effects. However, it is unclear whether the underlying basis of such effects is response competition or changes in the calculus of causation.

Modelling root reinforcement in shallow forest soils

Science.gov (United States)

Skaugset, Arne E.

1997-01-01

A hypothesis used to explain the relationship between timber harvesting and landslides is that tree roots add mechanical support to soil, thus increasing soil strength. Upon harvest, the tree roots decay which reduces soil strength and increases the risk of management -induced landslides. The technical literature does not adequately support this hypothesis. Soil strength values attributed to root reinforcement that are in the technical literature are such that forested sites can't fail and all high risk, harvested sites must fail. Both unstable forested sites and stable harvested sites exist, in abundance, in the real world thus, the literature does not adequately describe the real world. An analytical model was developed to calculate soil strength increase due to root reinforcement. Conceptually, the model is composed of a reinforcing element with high tensile strength, i.e. a conifer root, embedded in a material with little tensile strength, i.e. a soil. As the soil fails and deforms, the reinforcing element also deforms and stretches. The lateral deformation of the reinforcing element is treated analytically as a laterally loaded pile in a flexible foundation and the axial deformation is treated as an axially loaded pile. The governing differential equations are solved using finite-difference approximation techniques. The root reinforcement model was tested by comparing the final shape of steel and aluminum rods, parachute cord, wooden dowels, and pine roots in direct shear with predicted shapes from the output of the root reinforcement model. The comparisons were generally satisfactory, were best for parachute cord and wooden dowels, and were poorest for steel and aluminum rods. A parameter study was performed on the root reinforcement model which showed reinforced soil strength increased with increasing root diameter and soil depth. Output from the root reinforcement model showed a strain incompatibility between large and small diameter roots. The peak

Modeling of geosynthetic reinforced capping systems

International Nuclear Information System (INIS)

Viswanadham, B.V.S.; Koenig, D.; Jessberger, H.L.

1997-01-01

The investigation deals with the influence of a geosynthetic reinforcement on the deformation behavior and sealing efficiency of the reinforced mineral sealing layer at the onset of non-uniform settlements. The research program is mainly concentrated in studying the influence of reinforcement inclusion in restraining cracks and crack propagation due to soil-geosynthetic bond efficiency. Centrifuge model tests are conducted in the 500 gt capacity balanced beam Bochum geotechnical Centrifuge (Z1) simulating a differential deformation of a mineral sealing layer of a landfill with the help of trap-door arrangement. By comparing the performance of the deformed mineral sealing layer with and without geogrid, the reinforcement ability of the geogrid in controlling the crack propagation and permeability of the mineral swing layer is evaluated

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.

Geo synthetic-reinforced Pavement systems

International Nuclear Information System (INIS)

Zornberg, J. G.

2014-01-01

Geo synthetics have been used as reinforcement inclusions to improve pavement performance. while there are clear field evidence of the benefit of using geo synthetic reinforcements, the specific conditions or mechanisms that govern the reinforcement of pavements are, at best, unclear and have remained largely unmeasured. Significant research has been recently conducted with the objectives of: (i) determining the relevant properties of geo synthetics that contribute to the enhanced performance of pavement systems, (ii) developing appropriate analytical, laboratory and field methods capable of quantifying the pavement performance, and (iii) enabling the prediction of pavement performance as a function of the properties of the various types of geo synthetics. (Author)

Reinforcement of Conducting Silver-based Materials

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Heike JUNG

2014-09-01

Full Text Available Silver is a well-known material in the field of contact materials because of its high electrical and thermal conductivity. However, due to its bad mechanical and switching properties, silver alloys or reinforcements of the ductile silver matrix are required. Different reinforcements, e. g. tungsten, tungsten carbide, nickel, cadmium oxide or tin oxide, are used in different sectors of switches. To reach an optimal distribution of these reinforcements, various manufacturing techniques (e. g. powder blending, preform infiltration, wet-chemical methods, internal oxidation are being used for the production of these contact materials. Each of these manufacturing routes offers different advantages and disadvantages. The mechanical alloying process displays a successful and efficient method to produce particle-reinforced metal-matrix composite powders. This contribution presents the obtained fine disperse microstructure of tungsten-particle-reinforced silver composite powders produced by the mechanical alloying process and displays this technique as possible route to provide feedstock powders for subsequent consolidation processes. DOI: http://dx.doi.org/10.5755/j01.ms.20.3.4889

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.

Topology optimization of reinforced concrete beams by a spread-over reinforcement model with fixed grid mesh

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Benjapon Wethyavivorn

2011-02-01

Full Text Available For this investigation, topology optimization was used as a tool to determine the optimal reinforcement for reinforcedconcrete beam. The topology optimization process was based on a unit finite element cell with layers of concrete and steel.The thickness of the reinforced steel layer of this unit cell was then adjusted when the concrete layer could not carry thetensile or compressive stress. At the same time, unit cells which carried very low stress were eliminated. The process wasperformed iteratively to create a topology of reinforced concrete beam which satisfied design conditions.

Radiation resistance of the carbon fiber reinforced composite material with PEEK as the matrix resin

International Nuclear Information System (INIS)

Sasuga, Tsuneo; Seguchi, Tadao; Sakai, Hideo; Nakakura, Toshiyuki; Masutani, Masahiro.

1987-01-01

In the fast breeder reactor etc. the structural materials are exposed to various environment, i.e., repeated high and low temperature, stress, etc. Irradiation effect (electron radiation) in the mechanical characteristic at low and high temperature has been studied in the PEEK-CF, polyarylether · ether · ketone - carbon fiber composite. Following are the results. (1) Radiation resistance of PEEK-CF is higher than that of PEEK-PES-CF, PEEK - polyethersulfone surface treated CF composite. In PEEK-PES-CF, PES is deteriorated by irradiation so the adhesive power lowers. (2) In the unirradiated PEEK-CF, its mechanical characteristic decreases beyond 140 deg C. With increase of the radiation dose, however, the characteristic rises. (3) Mechanical characteristic of PEEK-CF thus little drops by the heat treatment after the irradiation. (Mori, K.)

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.

Acquisition with partial and continuous reinforcement in pigeon autoshaping.

Science.gov (United States)

Gottlieb, Daniel A

2004-08-01

Contemporary time accumulation models make the unique prediction that acquisition of a conditioned response will be equally rapid with partial and continuous reinforcement, if the time between conditioned stimuli is held constant. To investigate this, acquisition of conditioned responding was examined in pigeon autoshaping under conditions of 100% and 25% reinforcement, holding intertrial interval constant. Contrary to what was predicted, evidence for slowed acquisition in partially reinforced animals was observed with several response measures. However, asymptotic performance was superior with 25% reinforcement. A switching of reinforcement contingencies after initial acquisition did not immediately affect responding. After further sessions, partial reinforcement augmented responding, whereas continuous reinforcement did not, irrespective of an animal's reinforcement history. Subsequent training with a novel stimulus maintained the response patterns. These acquisition results generally support associative, rather than time accumulation, accounts of conditioning.

Brain network response underlying decisions about abstract reinforcers.

Science.gov (United States)

Mills-Finnerty, Colleen; Hanson, Catherine; Hanson, Stephen Jose

2014-12-01

Decision making studies typically use tasks that involve concrete action-outcome contingencies, in which subjects do something and get something. No studies have addressed decision making involving abstract reinforcers, where there are no action-outcome contingencies and choices are entirely hypothetical. The present study examines these kinds of choices, as well as whether the same biases that exist for concrete reinforcer decisions, specifically framing effects, also apply during abstract reinforcer decisions. We use both General Linear Model as well as Bayes network connectivity analysis using the Independent Multi-sample Greedy Equivalence Search (IMaGES) algorithm to examine network response underlying choices for abstract reinforcers under positive and negative framing. We find for the first time that abstract reinforcer decisions activate the same network of brain regions as concrete reinforcer decisions, including the striatum, insula, anterior cingulate, and VMPFC, results that are further supported via comparison to a meta-analysis of decision making studies. Positive and negative framing activated different parts of this network, with stronger activation in VMPFC during negative framing and in DLPFC during positive, suggesting different decision making pathways depending on frame. These results were further clarified using connectivity analysis, which revealed stronger connections between anterior cingulate, insula, and accumbens during negative framing compared to positive. Taken together, these results suggest that not only do abstract reinforcer decisions rely on the same brain substrates as concrete reinforcers, but that the response underlying framing effects on abstract reinforcers also resemble those for concrete reinforcers, specifically increased limbic system connectivity during negative frames. Copyright © 2014 Elsevier Inc. All rights reserved.

Long-term performance of GFRP reinforcement : technical report.

Science.gov (United States)

2009-12-01

Significant research has been performed on glass fiber-reinforced polymer (GFRP) concrete reinforcement. : This research has shown that GFRP reinforcement exhibits high strengths, is lightweight, can decrease time of : construction, and is corrosion ...

The effect of concrete strength and reinforcement on toughness of reinforced concrete beams

OpenAIRE

Carneiro, Joaquim A. O.; Jalali, Said; Teixeira, Vasco M. P.; Tomás, M.

2005-01-01

The objective pursued with this work includes the evaluating of the strength and the total energy absorption capacity (toughness) of reinforced concrete beams using different amounts of steel-bar reinforcement. The experimental campaign deals with the evaluation of the threshold load prior collapse, ultimate load and deformation, as well as the beam total energy absorption capacity, using a three point bending test. The beam half span displacement was measured using a displacement transducer,...

Concrete cover cracking due to uniform reinforcement corrosion

DEFF Research Database (Denmark)

Solgaard, Anders Ole Stubbe; Michel, Alexander; Geiker, Mette Rica

2013-01-01

and reinforcement de-passivation is a frequently used limit state. The present paper investigates an alternative limit state: corrosion-induced cover cracking. Results from numerical simulations of concrete cover cracking due to reinforcement corrosion are presented. The potential additional service life...... is calculated using literature data on corrosion rate and Faraday’s law. The parameters varied comprise reinforcement diameter, concrete cover thickness and concrete material properties, viz. concrete tensile strength and ductility (plain concrete and fibre reinforced concrete). Results obtained from......Service life design (SLD) is an important tool for civil engineers to ensure that the structural integrity and functionality of the structure is not compromised within a given time frame, i.e. the service life. In SLD of reinforced concrete structures, reinforcement corrosion is of major concern...

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.

Role of biological mesh in surgical treatment of paracolostomy hernias Uso de prótese biológica no tratamento cirúrgico de hérnias paracolostômicas

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Sergio Eduardo Alonso Araujo

2005-08-01

Full Text Available BACKGROUND: Paracolostomy hernia is a frequent complication of intestinal stoma. Its correction can be made through relocation of the colostomy or by keeping it in place and performing abdominal wall reinforcement through direct suturing with or without a prosthesis. METHOD: Results of surgical treatment of paracolostomy hernias were analyzed in 22 patients who underwent surgery in our hospital during the past 15 years, with or without biological mesh (bovine pericardium. All patients had terminal colostomies after abdominoperineal excision of the rectum. RESULTS: In 15 (68.2% patients, hernia correction was made by maintaining the colostomy in place, in 2 of them (9.1% without reinforcement, and in the other 13 (59.1% through reinforcement of the aponeurosis with biological mesh. In the 7 (31.8% other patients, hernia correction was accomplished by relocation of the colostomy. The mean follow-up period was 50.2 months. Recurrence was observed in 3 (13.6% patients after a median of 16 months post-correction. CONCLUSION: Paracolostomy hernia remains a surgical challenge due to its high recurrence rate. Primary repair using a prosthesis of biological material may be preferable since muscle-aponeurotic weakness is frequently observed.Hérnias paracolostômicas são complicações freqüentes de estomas intestinais. A correção pode ser realizada através do seu reposicionamento ou mantendo a mesma localização, associada ao reforço da parede abdominal com ou sem o emprego de prótese. MÉTODOS: Os resultados do tratamento cirúrgico de hérnias paracolostômicas são analisados em 22 pacientes em nosso serviço nos últimos 15 anos. Todos os pacientes eram portadores de colostomias terminais após ressecção abdominoperineal do reto. RESULTADOS: Em 15 (68,2% pacientes, a correção da hérnia foi realizada mantendo-se a colostomia no local original, em 2 (9,1% deles através de herniorrafia simples e em 13 (59,1% com reforço da aponeurose com

Quenched Reinforcement Exposed to Fire

DEFF Research Database (Denmark)

Hertz, Kristian Dahl

2006-01-01

.0% is seldom found in “slack” (not prestressed) reinforcement, but 2.0% stresses might be relevant for reinforcement in T shaped cross sections and for prestressed structures, where large strains can be applied. All data are provided in a “HOT” condition during a fire and in a “COLD” condition after a fire...

Design of reinforced concrete plates and shells

International Nuclear Information System (INIS)

Schulz, M.

1984-01-01

Nowadays, the internal forces of reinforced concrete laminar structures can be easily evaluated by the finite element procedures. The longitudinal design in each direction is not adequate, since the whole set of internal forces in each point must be concomitantly considered. The classic formulation for the design and new design charts which bring reduction of the amount of necessary reinforcement are presented. A rational reinforced concrete mathematical theory which makes possible the limit state design of plates and shells is discussed. This model can also be applied to define the constitutive relationships of laminar finite elements of reinforced concrete. (Author) [pt

Effect of steel reinforcement with different degree of corrosion on degeneration of mechanical performance of reinforced concrete frame joints

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Wu Xu

2016-02-01

Full Text Available Beam-column joints which shoulders high-level and vertical shearing effect that maintains balance of beam and column end is the major component influencing the performance of the whole framework. Post earthquake investigation suggests that collapse of frame structure is induced by failure of joints in most cases. Thus, beam-column joints must have strong bearing capacity and good ductility, and reinforced concrete structure just meets the above requirement. But corrosion caused by long time use of reinforced concrete framework will lead to degeneration of mechanical performance of joints. To find out the rule of effect of steel reinforcement with different corrosion rate on degeneration of bearing capacity of reinforced concrete framework joints, this study made a nonlinear numerical analysis on fifteen models without stirrup in the core area of reinforced concrete frame joints using displacement method considering axial load ratio of column end and constraint condition. This work aims to find out the key factor that influences mechanical performance of joints, thus to provide a basis for repair and reinforcement of degenerated framework joints.

Stability of reinforced cemented backfills

International Nuclear Information System (INIS)

Mitchell, R.J.; Stone, D.M.

1987-01-01

Mining with backfill has been the subject of several international meetings in recent years and a considerable research effort is being applied to improve both mining economics and ore recovery by using backfill for ground support. Classified mill tailings sands are the most commonly used backfill material but these fine sands must be stabilized before full ore pillar recovery can be achieved. Normal portland cement is generally used for stabilization but the high cost of cement prohibits high cement usage. This paper considers the use of reinforcements in cemented fill to reduce the cement usage. It is concluded that strong cemented layers at typical spacings of about 3 meters in a low cement content bulk fill can reinforce the fill and reduce the overall cement usage. Fibre reinforcements introduced into strong layers or into bulk fills are also known to be effective in reducing cement usage. Some development work is needed to produce the ideal type of anchored fibre in order to realize economic gains from fibre-reinforced fills

Fatigue Performance of Fiber Reinforced Concrete

DEFF Research Database (Denmark)

Jun, Zhang; Stang, Henrik

1996-01-01

The objective of the present study is to obtain basic data of fibre reinforced concrete under fatigue load and to set up a theoretical model based on micromechanics. In this study, the bridging stress in fiber reinforced concrete under cyclic tensile load was investigted in details. The damage...... mechanism of the interface between fiber and matrix was proposed and a rational model given. Finally, the response of a steel fiber reinforced concrete beam under fatigue loading was predicted based on this model and compared with experimental results....

Strain rate effects on reinforcing steels in tension

Science.gov (United States)

Cadoni, Ezio; Forni, Daniele

2015-09-01

It is unquestionable the fact that a structural system should be able to fulfil the function for which it was created, without being damaged to an extent disproportionate to the cause of damage. In addition, it is an undeniable fact that in reinforced concrete structures under severe dynamic loadings, both concrete and reinforcing bars are subjected to high strain-rates. Although the behavior of the reinforcing steel under high strain rates is of capital importance in the structural assessment under the abovementioned conditions, only the behaviour of concrete has been widely studied. Due to this lack of data on the reinforcing steel under high strain rates, an experimental program on rebar reinforcing steels under high strain rates in tension is running at the DynaMat Laboratory. In this paper a comparison of the behaviour in a wide range of strain-rates of several types of reinforcing steel in tension is presented. Three reinforcing steels, commonly proposed by the European Standards, are compared: B500A, B500B and B500C. Lastly, an evaluation of the most common constitutive laws is performed.

Effect of kenaf fiber in reinforced concrete slab

Science.gov (United States)

Syed Mohsin, S. M.; Baarimah, A. O.; Jokhio, G. A.

2018-04-01

The effect of kenaf fibers in reinforced concrete slab with different thickness is discusses and presented in this paper. Kenaf fiber is a type of natural fiber and is added in the reinforced concrete slab to improve the structure strength and ductility. For this study, three types of mixtures were prepared with fiber volume fraction of 0%, 1% and 2%, respectively. The design compressive strength considered was 20 MPa. Six cubes were prepared to be tested at 7th and 28th day. A total of six reinforced concrete slab with two variances of thickness were also prepared and tested under four-point bending test. The differences in the thickness is to study the potential of kenaf fiber to serve as part of shear reinforcement in reinforced concrete slab that was design to fail in shear. It was observed that, addition of kenaf fiber in reinforced concrete slab improves the flexural strength and ductility of the reinforced concrete slab. In the slab with reduction in thickness, the mode of failure change from brittle to ductile with the inclusion of kenaf fiber.

Influence of reinforcement on strains within maxillary implant overdentures.

Science.gov (United States)

Takahashi, Toshihito; Gonda, Tomoya; Maeda, Yoshinobu

2015-01-01

The purpose of this study was to examine the influence of reinforcement of an embedded cast on the strains within maxillary implant overdentures. A maxillary edentulous model with implants placed bilaterally in the canine positions, dome-shaped copings, and experimental overdentures was fabricated. Rosette-type strain gauges were attached in the canine positions and at three points along the midline of the polished surface of the denture and connected to the sensor interface controlled by a personal computer. Experimental dentures with five different reinforcements were tested: without reinforcement; with a cast cobalt-chrome reinforcement over the residual ridge and the tops of the copings; with the same reinforcement from first molar to first molar, over the residual ridge and the tops of the copings; with the same reinforcement over the residual ridge and the sides of the copings; and with the same reinforcement from first molar to first molar, over the residual ridge and the sides of the copings. A vertical occlusal load of 49 N was applied to the first premolar and then to the first molar, and the strains were measured and compared by analysis of variance. In both loading situations, significantly less strain was recorded in dentures with reinforcement than in those without reinforcement. When the first premolar was loaded on dentures with and without palatal reinforcement at the first premolars, the strains on the denture with reinforcement over the tops of the copings were significantly lower than on the denture with reinforcement over the sides of the copings at the canine position. Cast reinforcement over the residual ridge and the top of copings embedded in an acrylic base reduced the strain from occlusal stress on maxillary implant overdentures.

Review of Carbon Fiber Reinforced Polymer Reinforced Material in Concrete Structure

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Ayuddin Ayuddin

2016-05-01

Full Text Available Carbon Fiber Reinforced Polymer (FRP is a material that is lightweight, strong, anti-magnetic and corrosion resistant. This material can be used as an option to replace the steel material in concrete construction or as material to improve the strength of existing construction. CFRP is quite easy to be attached to the concrete structure and proved economically used as a material for repairing damaged structures and increase the resilience of structural beams, columns, bridges and other parts of the structure against earthquakes. CFRP materials can be shaped sheet to be attached to the concrete surface. Another reason is due to the use of CFRP has a higher ultimate strength and lower weight compared to steel reinforcement so that the handling is significantly easier. Through this paper suggests that CFRP materials can be applied to concrete structures, especially on concrete columns. Through the results of experiments conducted proved that the concrete columns externally wrapped with CFRP materials can increase the strength. This treatment is obtained after testing experiments on 130 mm diameter column with a height of 700 mm with concentric loading method to collapse. The experimental results indicate that a column is wrapped externally with CFRP materials can achieve a load capacity of 250 kN compared to the concrete columns externally without CFRP material which only reached 150 kN. If the column is given internally reinforcing steel and given externally CFRP materials can reach 270 kN. It shows that CFRP materials can be used for concrete structures can even replace reinforcing steel that has been widely used in building construction in Indonesia.

Aproximaciones polinómicas al método parábola-rectángulo

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de Miguel Rodríguez, José L.

1988-04-01

Full Text Available The article puts forward the formulation of flexure reinforcement in rectangular sections according to the parabola-rectangle model, obtains mass development and discusses the precision obtained by polynomial formulations of varios orders. Said formulation allows the author to ponder the different effects of each variable included in the original formulation. He reaches the conclusion that a first order approximation is sufficiently precise in practical use, an interesting physical interpretation, and notable simplicity, not having any variable difficult to estimate in real cases. The study is extended to the case of compressive reinforcement. Here it is found that the same formulation allows the case to be solved. For T-sections, the author concludes that the simplified expression is too conservative, and suggests corrections in it.

Se expone la formulación de la armadura de flexión en secciones rectangulares según el modelo parábola-rectángulo, se obtiene el desarrollo en serie y se discute la precisión obtenida por las formulaciones polinómicas de varios órdenes. Dicha formulación permite ponderar la diferente repercusión de cada variable incluida en la formulación original. Se llega a concluir que una aproximación de primer orden posee en la práctica suficiente precisión, una interesante interpretación física, y una notable simplicidad, no conteniendo alguna variable de difícil estimación en los casos reales. El estudio se amplía al caso de armadura de compresión, comprobándose que la misma formulación permite resolver este caso. Para secciones en forma de T se concluye que la expresión simplificada es conservadora en demasía, y se sugieren correcciones a la misma.

Simultaneous determination of 41 multiclass organic pollutants in environmental waters by means of polyethersulfone microextraction followed by liquid chromatography-tandem mass spectrometry.

Science.gov (United States)

Mijangos, Leire; Ziarrusta, Haizea; Olivares, Maitane; Zuloaga, Olatz; Möder, Monika; Etxebarria, Nestor; Prieto, Ailette

2018-01-01

A new procedure using polyethersulfone (PES) microextraction followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis was developed in this work for the simultaneous determination of 41 multiclass priority and emerging organic pollutants including herbicides, hormones, personal care products, and pharmaceuticals, among others, in seawater, wastewater treatment plant (WWTP) effluents, and estuary samples. The optimization of the analysis included two different chromatographic columns and different variables (polarity, fragmentor voltage, collision energy, and collision cell accelerator) of the mass spectrometer. In the case of PES extraction, ion strength of the water, pH, addition of EDTA, and the amount of the polymeric material were thoroughly investigated. The developed procedure was compared with a previously validated one based on a standard solid-phase extraction (SPE). In contrast to the SPE protocol, the PES method allowed a cost-efficient extraction of complex aqueous samples with lower matrix effect from 120 mL of water sample. Satisfactory and comparable apparent recovery values (80-119 and 70-131%) and method quantification limits (MQLs, 0.4-26 and 0.2-23 ng/L) were obtained for PES and SPE procedures, respectively, regardless of the matrix. Repeatability values lower than 27% were obtained. Finally, the developed methods were applied to the analysis of real samples from the Basque Country and irbesartan, valsartan, acesulfame, and sucralose were the analytes most often detected at the highest concentrations (51-1096 ng/L). Graphical abstract Forty-one multiclass pollutant determination in environmental waters by means of PES/SPE-LC-MS/MS.

FEM performance of concrete beams reinforced by carbon fiber bars

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Hasan Hashim

2018-01-01

Full Text Available Concrete structures may be vulnerable to harsh environment, reinforcement with Fiber Reinforced Polymer (FRP bars have an increasing acceptance than normal steel. The nature of (FRP bar is (non-corrosive which is very beneficial for increased durability as well as the reinforcement of FRP bar has higher strength than steel bar. FRP usage are being specified more and more by public structural engineers and individual companies as main reinforcement and as strengthening of structures. Steel reinforcement as compared to (FRP reinforcement are decreasingly acceptable for structural concrete reinforcement including precast concrete, cast in place concrete, columns, beams and other components. Carbon Fiber Reinforcement Polymer (CFRP have a very high modulus of elasticity “high modulus” and very high tensile strength. In aerospace industry, CFRP with high modulus are popular among all FRPs because it has a high strength to weight ratio. In this research, a finite element models will be used to represent beams with Carbon Fiber Reinforcement and beams with steel reinforcement. The primary objective of the research is the evaluation of the effect of (CFR on beam reinforcement.

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

Depression, Activity, and Evaluation of Reinforcement

Science.gov (United States)

Hammen, Constance L.; Glass, David R., Jr.

1975-01-01

This research attempted to find the causal relation between mood and level of reinforcement. An effort was made to learn what mood change might occur if depressed subjects increased their levels of participation in reinforcing activities. (Author/RK)

The genetics of speciation by reinforcement.

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Daniel Ortiz-Barrientos

2004-12-01

Full Text Available Reinforcement occurs when natural selection strengthens behavioral discrimination to prevent costly interspecies matings, such as when matings produce sterile hybrids. This evolutionary process can complete speciation, thereby providing a direct link between Darwin's theory of natural selection and the origin of new species. Here, by examining a case of speciation by reinforcement in Drosophila,we present the first high-resolution genetic study of variation within species for female mating discrimination that is enhanced by natural selection. We show that reinforced mating discrimination is inherited as a dominant trait, exhibits variability within species, and may be influenced by a known set of candidate genes involved in olfaction. Our results show that the genetics of reinforced mating discrimination is different from the genetics of mating discrimination between species, suggesting that overall mating discrimination might be a composite phenomenon, which in Drosophila could involve both auditory and olfactory cues. Examining the genetics of reinforcement provides a unique opportunity for both understanding the origin of new species in the face of gene flow and identifying the genetic basis of adaptive female species preferences, two major gaps in our understanding of speciation.

Experimental investigation of the relation between damage at the concrete-steel interface and initiation of reinforcement corrosion in plain and fibre reinforced concrete

DEFF Research Database (Denmark)

Michel, Alexander; Solgaard, Anders Ole Stubbe; Pease, Bradley Justin

2013-01-01

Cracks in covering concrete are known to hasten initiation of steel corrosion in reinforced concrete structures. To minimise the impact of cracks on the deterioration of reinforced concrete structures, current approaches in (inter)national design codes often limit the concrete surface crack width....... Recent investigations however, indicate that the concrete-reinforcement interfacial condition is a more fundamental criterion related to reinforcement corrosion. This work investigates the relation between macroscopic damage at the concrete-steel interface and corrosion initiation of reinforcement...... embedded in plain and fibre reinforced concrete. Comparisons of experimental and numerical results indicate a strong correlation between corrosion initiation and interfacial condition....

Environmental Durability of Reinforced Concrete Deck Girders Strengthened for Shear with Surface-Bonded Carbon Fiber-Reinforced Polymer

Science.gov (United States)

2009-05-01

"This research investigated the durability of carbon fiber-reinforced polymer composites (CFRP) used for shear strengthening reinforced concrete deck girders. Large beams were used to avoid accounting for size effects in the data analysis. The effort...

Seismic Stability of Reinforced Soil Slopes

DEFF Research Database (Denmark)

Tzavara, I.; Zania, Varvara; Tsompanakis, Y.

2012-01-01

Over recent decades increased research interest has been observed on the dynamic response and stability issues of earth walls and reinforced soil structures. The current study aims to provide an insight into the dynamic response of reinforced soil structures and the potential of the geosynthetics...... to prevent the development of slope instability taking advantage of their reinforcing effect. For this purpose, a onedimensional (SDOF) model, based on Newmark’s sliding block model as well as a two-dimensional (plane-strain) dynamic finite-element analyses are conducted in order to investigate the impact...

Reinforcement of RC structure by carbon fibers

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Kissi B.

2016-01-01

Full Text Available In recent years, rehabilitation has been the subject of extensive research due to the increased spending on building maintenance work and restoration of built works. In all cases, it is essential to carry out methods of reinforcement or maintenance of structural elements, following an inspection analysis and methodology of a correct diagnosis. This research focuses on the calculation of the necessary reinforcement sections of carbon fiber for structural elements with reinforced concrete in order to improve their load bearing capacity and rigidity. The different results obtained reveal a considerable gain in resistance and deformation capacity of reinforced sections without significant increase in the weight of the rehabilitated elements.

Methodology of shell structure reinforcement layout optimization

Science.gov (United States)

Szafrański, Tomasz; Małachowski, Jerzy; Damaziak, Krzysztof

2018-01-01

This paper presents an optimization process of a reinforced shell diffuser intended for a small wind turbine (rated power of 3 kW). The diffuser structure consists of multiple reinforcement and metal skin. This kind of structure is suitable for optimization in terms of selection of reinforcement density, stringers cross sections, sheet thickness, etc. The optimisation approach assumes the reduction of the amount of work to be done between the optimization process and the final product design. The proposed optimization methodology is based on application of a genetic algorithm to generate the optimal reinforcement layout. The obtained results are the basis for modifying the existing Small Wind Turbine (SWT) design.

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 ...

Behaviour of concrete beams reinforced withFRP prestressed concrete prisms

Science.gov (United States)

Svecova, Dagmar

The use of fibre reinforced plastics (FRP) to reinforce concrete is gaining acceptance. However, due to the relatively low modulus of FRP, in comparison to steel, such structures may, if sufficient amount of reinforcement is not used, suffer from large deformations and wide cracks. FRP is generally more suited for prestressing. Since it is not feasible to prestress all concrete structures to eliminate the large deflections of FRP reinforced concrete flexural members, researchers are focusing on other strategies. A simple method for avoiding excessive deflections is to provide sufficiently high amount of FRP reinforcement to limit its stress (strain) to acceptable levels under service loads. This approach will not be able to take advantage of the high strength of FRP and will be generally uneconomical. The current investigation focuses on the feasibility of an alternative strategy. This thesis deals with the flexural and shear behaviour of concrete beams reinforced with FRP prestressed concrete prisms. FRP prestressed concrete prisms (PCP) are new reinforcing bars, made by pretensioning FRP and embedding it in high strength grout/concrete. The purpose of the research is to investigate the feasibility of using such pretensioned rebars, and their effect on the flexural and shear behaviour of reinforced concrete beams over the entire loading range. Due to the prestress in the prisms, deflection of concrete beams reinforced with this product is substantially reduced, and is comparable to similarly steel reinforced beams. The thesis comprises both theoretical and experimental investigations. In the experimental part, nine beams reinforced with FRP prestressed concrete prisms, and two companion beams, one steel and one FRP reinforced were tested. All the beams were designed to carry the same ultimate moment. Excellent flexural and shear behaviour of beams reinforced with higher prestressed prisms is reported. When comparing deflections of three beams designed to have the

A conditioned reinforcer did not help to maintain an operant conditioning in the absence of a primary reinforcer in horses.

Science.gov (United States)

Lansade, Léa; Calandreau, Ludovic

2018-01-01

The use of conditioned reinforcers is increasingly promoted in animal training. Surprisingly, the efficiency of their use remains to be demonstrated in horses. This study aimed to determine whether an auditory signal which had previously been associated with a food reward 288 times could be used as a conditioned reinforcer to replace the primary reinforcer in an unrelated operant conditioning procedure. Fourteen horses were divided into two groups of 7: No Reinforcement (NR) and Conditioned Reinforcement (CR). All horses underwent nine sessions of Pavlovian conditioning during which the word "good" was associated with food (32 associations/session). The horses then followed five sessions of operant conditioning (30 trials/session) during which they had to touch a cone signaled by an experimenter to receive a food reward. The last day, horses underwent one test session of the operant response: no reward was given, but the word "good" was said each time a CR horse touched the cone. Nothing was said in the NR group. CR horses did not achieve more correct trials than NR horses during the test. These findings again show that the conditioned reinforcement was ineffective when used instead of the primary reinforcement to maintain conditioning. Copyright © 2017 Elsevier B.V. All rights reserved.

Design aid for shear strengthening of reinforced concrete T-joints using carbon fiber reinforced plastic composites

Science.gov (United States)

Gergely, Ioan

The research presented in the present work focuses on the shear strengthening of beam column joints using carbon fiber composites, a material considered in seismic retrofit in recent years more than any other new material. These composites, or fiber reinforced polymers, offer huge advantages over structural steel reinforced concrete or timber. A few of these advantages are the superior resistance to corrosion, high stiffness to weight and strength to weight ratios, and the ability to control the material's behavior by selecting the orientation of the fibers. The design and field application research on reinforced concrete cap beam-column joints includes analytical investigations using pushover analysis; design of carbon fiber layout, experimental tests and field applications. Several beam column joints have been tested recently with design variables as the type of composite system, fiber orientation and the width of carbon fiber sheets. The surface preparation has been found to be critical for the bond between concrete and composite material, which is the most important factor in joint shear strengthening. The final goal of this thesis is to develop design aids for retrofitting reinforced concrete beam column joints. Two bridge bents were tested on the Interstate-15 corridor. One bent was tested in the as-is condition. Carbon fiber reinforced plastic composite sheets were used to externally reinforce the second bridge bent. By applying the composite, the displacement ductility has been doubled, and the bent overall lateral load capacity has been increased as well. The finite element model (using DRAIN-2DX) was calibrated to model the actual stiffness of the supports. The results were similar to the experimental findings.

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...

STRUCTURAL PERFORMANCE OF DEGRADED REINFORCED CONCRETE MEMBERS

International Nuclear Information System (INIS)

Braverman, J.I.; Miller, C.A.; Ellingwood, B.R.; Naus, D.J.; Hofmayer, C.H.; Bezler, P.; Chang, T.Y.

2001-01-01

This paper describes the results of a study to evaluate, in probabilistic terms, the effects of age-related degradation on the structural performance of reinforced concrete members at nuclear power plants. The paper focuses on degradation of reinforced concrete flexural members and shear walls due to the loss of steel reinforcing area and loss of concrete area (cracking/spalling). Loss of steel area is typically caused by corrosion while cracking and spalling can be caused by corrosion of reinforcing steel, freeze-thaw, or aggressive chemical attack. Structural performance in the presence of uncertainties is depicted by a fragility (or conditional probability of failure). The effects of degradation on the fragility of reinforced concrete members are calculated to assess the potential significance of various levels of degradation. The fragility modeling procedures applied to degraded concrete members can be used to assess the effects of degradation on plant risk and can lead to the development of probability-based degradation acceptance limits

Limit analysis of solid reinforced concrete structures

DEFF Research Database (Denmark)

Larsen, Kasper Paaske

2009-01-01

Recent studies have shown that Semidefinite Programming (SDP) can be used effectively for limit analysis of isotropic cohesive-frictional continuums using the classical Mohr-Coulomb yield criterion. In this paper we expand on this previous research by adding reinforcement to the model and a solid...... reinforcement and it is therefore possible to analyze structures with complex reinforcement layouts. Tests are conducted to validate the method against well-known analytical solutions....

Reinforced flexural elements for TEMP-STRESS Program

International Nuclear Information System (INIS)

Marchertas, A.H.; Kennedy, J.M.; Pfeiffer, P.A.

1987-06-01

The implementation of reinforced flexural elements into the thermal-mechanical finite element program TEMP-STRESS is described. With explicit temporal integration and dynamic relaxation capabilities in the program, the flexural elements provide an efficient method for the treatment of reinforced structures subjected to transient and static loads. The capability of the computer program is illustrated by the solution of several examples: the simulation of a reinforced concrete beam; simulations of a reinforced concrete containment shell which is subjected to internal pressurization, thermal gradients through the walls, and transient pressure loads. The results of this analysis are relevant in the structural design/safety evaluations of typical reactor containment structures. 22 refs., 13 figs

Integrating seawater desalination and wastewater reclamation forward osmosis process using thin-film composite mixed matrix membrane with functionalized carbon nanotube blended polyethersulfone support layer.

Science.gov (United States)

Choi, Hyeon-Gyu; Son, Moon; Choi, Heechul

2017-10-01

Thin-film composite mixed matrix membrane (TFC MMM) with functionalized carbon nanotube (fCNT) blended in polyethersulfone (PES) support layer was synthesized via interfacial polymerization and phase inversion. This membrane was firstly tested in lab-scale integrating seawater desalination and wastewater reclamation forward osmosis (FO) process. Water flux of TFC MMM was increased by 72% compared to that of TFC membrane due to enhanced hydrophilicity. Although TFC MMM showed lower water flux than TFC commercial membrane, enhanced reverse salt flux selectivity (RSFS) of TFC MMM was observed compared to TFC membrane (15% higher) and TFC commercial membrane (4% higher), representing membrane permselectivity. Under effluent organic matter (EfOM) fouling test, 16% less normalized flux decline of TFC MMM was observed compared to TFC membrane. There was 8% less decline of TFC MMM compared to TFC commercial membrane due to fCNT effect on repulsive foulant-membrane interaction enhancement, caused by negatively charged membrane surface. After 10 min physical cleaning, TFC MMM displayed higher recovered normalized flux than TFC membrane (6%) and TFC commercial membrane (4%); this was also supported by visualized characterization of fouling layer. This study presents application of TFC MMM to integrated seawater desalination and wastewater reclamation FO process for the first time. It can be concluded that EfOM fouling of TFC MMM was suppressed due to repulsive foulant-membrane interaction. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

Directory of Open Access Journals (Sweden)

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.

Reinforcement Corrosion: Numerical Simulation and Service Life Prediction

DEFF Research Database (Denmark)

Michel, Alexander

defects and b) define the end of service life once reinforcement corrosion is initiated neglecting corrosion processes during the propagation stage. The goal of this work was to develop a framework for the service life prediction of reinforced concrete covering initiation and propagation of chloride......Modelling of deterioration processes in concrete structures plays an increasing role in the design of reinforced concrete structures. Large sums are spent every year to ensure the durability of concrete structures, especially towards reinforcement corrosion. Improved durability provides increased...... structural reliability, economical improvements in form of less need for maintenance and repair as well as increased sustainability due to an increased energy and resource efficiency. Several service life prediction models dealing with reinforcement corrosion in concrete structurescan be found...

A shell approach for fibrous reinforcement forming simulations

Science.gov (United States)

Liang, B.; Colmars, J.; Boisse, P.

2018-05-01

Because of the slippage between fibers, the basic assumptions of classical plate and shell theories are not verified by fiber reinforcement during a forming. However, simulations of reinforcement forming use shell finite elements when wrinkles development is important. A shell formulation is proposed for the forming simulations of continuous fiber reinforcements. The large tensile stiffness leads to the quasi inextensibility in the fiber directions. The fiber bending stiffness determines the curvature of the reinforcement. The calculation of tensile and bending virtual works are based on the precise geometry of the single fiber. Simulations and experiments are compared for different reinforcements. It is shown that the proposed fibrous shell approach not only correctly simulates the deflections but also the rotations of the through thickness material normals.

Computadores y democracia económica

Directory of Open Access Journals (Sweden)

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

Directory of Open Access Journals (Sweden)

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

The power reinforcement framework revisited

DEFF Research Database (Denmark)

Nielsen, Jeppe; Andersen, Kim Normann; Danziger, James N.

2016-01-01

Whereas digital technologies are often depicted as being capable of disrupting long-standing power structures and facilitating new governance mechanisms, the power reinforcement framework suggests that information and communications technologies tend to strengthen existing power arrangements within...... public organizations. This article revisits the 30-yearold power reinforcement framework by means of an empirical analysis on the use of mobile technology in a large-scale programme in Danish public sector home care. It explores whether and to what extent administrative management has controlled decision......-making and gained most benefits from mobile technology use, relative to the effects of the technology on the street-level workers who deliver services. Current mobile technology-in-use might be less likely to be power reinforcing because it is far more decentralized and individualized than the mainly expert...

Shear behaviour of reinforced phyllite concrete beams

International Nuclear Information System (INIS)

Adom-Asamoah, Mark; Owusu Afrifa, Russell

2013-01-01

Highlights: ► Phyllite concrete beams often exhibited shear with anchorage bond failure. ► Different shear design provisions for reinforced phyllite beams are compared. ► Predicted shear capacity of phyllite beams must be modified by a reduction factor. -- Abstract: The shear behaviour of concrete beams made from phyllite aggregates subjected to monotonic and cyclic loading is reported. First diagonal shear crack load of beams with and without shear reinforcement was between 42–58% and 42–92% of the failure loads respectively. The phyllite concrete beams without shear links had lower post-diagonal cracking shear resistance compared to corresponding phyllite beams with shear links. As a result of hysteretic energy dissipation, limited cyclic loading affected the stiffness, strength and deformation of the phyllite beams with shear reinforcement. Generally, beams with and without shear reinforcement showed anchorage bond failure in addition to the shear failure due to high stress concentration near the supports. The ACI, BS and EC codes are conservative for the prediction of phyllite concrete beams without shear reinforcement but they all overestimate the shear strength of phyllite concrete beams with shear reinforcement. It is recommended that the predicted shear capacity of phyllite beams reinforced with steel stirrups be modified by a reduction factor of 0.7 in order to specify a high enough safety factor on their ultimate strength. It is also recommended that susceptibility of phyllite concrete beams to undergo anchorage bond failure is averted in design by the provision of greater anchorage lengths than usually permitted.

Application of Fiber Reinforcement Concrete Technique in Civil ...

African Journals Online (AJOL)

modulus of elasticity, high tensile strength, improved fatigue and impact resistance. Reinforcing the concrete structures with fibers such as polyester is one of the possible ways to provide all the criteria of the durable repair material. This type of reinforcement is called Fiber Reinforcement of Concrete Structures. There is an ...

Design for whipping pipe impact on reinforced concrete panels

International Nuclear Information System (INIS)

Chen, C.C.; Gurbuz, O.

1984-01-01

This paper describes determination of local and overall effects on reinforced concrete panels due to whipping pipe impact in postulated pipe break events. Local damage includes the prediction of minimum concrete panel thickness required to prevent spalling from the back face of the target reinforced concrete panels. Evaluation of overall effect deals with the ductility ratio calculation for the target reinforced concrete panels. Design curves for determining the minimum panel thickness and the minimum reinforcement of reinforced concrete panels are presented in this paper for some cases commonly encountered in nuclear applications. The methodology and the results provided can be used to determine if an existing reinforced concrete wall is capable of resisting the whipping pipe impact, and consequently, if pipe whip restraints can be eliminated

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.

Scheduling reinforcement about once a day.

Science.gov (United States)

Eckerman, D A

1999-04-01

A pigeon earned its daily food by pecking a key according to reinforcement schedules that produced food about once per day. Fixed-interval (FI), Fixed-time (FT), and various complex schedules were arranged to demonstrate the degree to which a scalloped pattern of responding remained. Pausing continued until about an hour before the reinforcer could be earned for FIs of 12, 24, and 48 h. Pausing was not as long for FIs of 18, 19, and 23 h. Pausing of about 24 h was seen for FI 36 h. FT 24 h produced continued responding but at a diminished frequency. The pattern of responding was strongly controlled by the schedule of reinforcement and seemed relatively independent of the cycle of human activity in the surrounding laboratory. Effects of added ratio contingencies and of signaling the availability of reinforcement in FT were also examined. Signaled FTs of 5 min-3 h produced more responding during the signal (autoshaping) than did FTs of 19 or 24 h.

Fundamentals of fibre-reinforced soil engineering

CERN Document Server

Shukla, Sanjay Kumar

2017-01-01

This book is intended to serve as a one-stop reference on fibre-reinforced soils. Over the past 30-35 years, the engineering behaviour of randomly distributed/oriented fibre-reinforced soil, also called simply fibre-reinforced soil, has been investigated in detail by researchers and engineers worldwide. Waste fibres (plastic waste fibres, old tyre fibres, etc.) create disposal and environmental problems. Utilization of such fibres in construction can help resolve these concerns. Research studies and some field applications have shown that the fibres can be utilized in large quantities in geotechnical and civil engineering applications in a cost-effective and environmentally friendly manner. This book covers a complete description of fibres, their effects when included within a soil or other similar materials such as the fly ash, and their field applications. It gives a detailed view of fibre-reinforced soil engineering. The book will be useful to students, professional, and researchers alike, and can also ser...

La elite económica Argentina, 1810-1914

Directory of Open Access Journals (Sweden)

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.

Numerical estimation of concrete beams reinforced with FRP bars

Directory of Open Access Journals (Sweden)

Protchenko Kostiantyn

2016-01-01

Full Text Available This paper introduces numerical investigation on mechanical performance of a concrete beam reinforced with Fibre Reinforced Polymer (FRP bars, which can be competitive alternative to steel bars for enhancing concrete structures. The objective of this work is being identified as elaborating of reliable numerical model for predicting strength capacity of structural elements with implementation of Finite Element Analysis (FEA. The numerical model is based on experimental study prepared for the beams, which were reinforced with Basalt FRP (BFRP bars and steel bars (for comparison. The results obtained for the beams reinforced with steel bars are found to be in close agreement with the experimental results. However, the beams reinforced with BFRP bars in experimental programme demonstrated higher bearing capacity than those reinforced with steel bars, which is not in a good convergence with numerical results. Authors did attempt to describe the reasons on achieving experimentally higher bearing capacity of beams reinforced with BFRP bars.

Simulation analysis of impact tests of steel plate reinforced concrete and reinforced concrete slabs against aircraft impact and its validation with experimental results

International Nuclear Information System (INIS)

Sadiq, Muhammad; Xiu Yun, Zhu; Rong, Pan

2014-01-01

Highlights: • Simulation analysis is carried out with two constitutive concrete models. • Winfrith model can better simulate nonlinear response of concrete than CSCM model. • Performance of steel plate concrete is better than reinforced concrete. • Thickness of safety related structures can be reduced by adopting steel plates. • Analysis results, mainly concrete material models should be validated. - Abstract: The steel plate reinforced concrete and reinforced concrete structures are used in nuclear power plants for protection against impact of an aircraft. In order to compare the impact resistance performance of steel plate reinforced concrete and reinforced concrete slabs panels, simulation analysis of 1/7.5 scale model impact tests is carried out by using finite element code ANSYS/LS-DYNA. The damage modes of all finite element models, velocity time history curves of the aircraft engine and damage to aircraft model are compared with the impact test results of steel plate reinforced concrete and reinforced concrete slab panels. The results indicate that finite element simulation results correlate well with the experimental results especially for constitutive winfrith concrete model. Also, the impact resistance performance of steel plate reinforced concrete slab panels is better than reinforced concrete slab panels, particularly the rear face steel plate is very effective in preventing the perforation and scabbing of concrete than conventional reinforced concrete structures. In this way, the thickness of steel plate reinforced concrete structures can be reduced in important structures like nuclear power plants against impact of aircraft. It also demonstrates the methodology to validate the analysis procedure with experimental and analytical studies. It may be effectively employed to predict the precise response of safety related structures against aircraft impact

Halloysite reinforced epoxy composites with improved mechanical properties

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Saif Muhammad Jawwad

2016-03-01

Full Text Available Halloysite nanotubes (HNTs reinforced epoxy composites with improved mechanical properties were prepared. The prepared HNTs reinforced epoxy composites demonstrated improved mechanical properties especially the fracture toughness and flexural strength. The flexural modulus of nanocomposite with 6% mHNTs loading was 11.8% higher than that of neat epoxy resin. In addition, the nanocomposites showed improved dimensional stability. The prepared halloysite reinforced epoxy composites were characterized by thermal gravimetric analysis (TGA. The improved properties are attributed to the unique characteristics of HNTs, uniform dispersion of reinforcement and interfacial coupling.

Working Memory and Reinforcement Schedule Jointly Determine Reinforcement Learning in Children: Potential Implications for Behavioral Parent Training

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Elien Segers

2018-03-01

Full Text Available Introduction: Behavioral Parent Training (BPT is often provided for childhood psychiatric disorders. These disorders have been shown to be associated with working memory impairments. BPT is based on operant learning principles, yet how operant principles shape behavior (through the partial reinforcement (PRF extinction effect, i.e., greater resistance to extinction that is created when behavior is reinforced partially rather than continuously and the potential role of working memory therein is scarcely studied in children. This study explored the PRF extinction effect and the role of working memory therein using experimental tasks in typically developing children.Methods: Ninety-seven children (age 6–10 completed a working memory task and an operant learning task, in which children acquired a response-sequence rule under either continuous or PRF (120 trials, followed by an extinction phase (80 trials. Data of 88 children were used for analysis.Results: The PRF extinction effect was confirmed: We observed slower acquisition and extinction in the PRF condition as compared to the continuous reinforcement (CRF condition. Working memory was negatively related to acquisition but not extinction performance.Conclusion: Both reinforcement contingencies and working memory relate to acquisition performance. Potential implications for BPT are that decreasing working memory load may enhance the chance of optimally learning through reinforcement.

Optimizing the Flexural Strength of Beams Reinforced with Fiber Reinforced Polymer Bars Using Back-Propagation Neural Networks

Directory of Open Access Journals (Sweden)

Bahman O. Taha

2015-06-01

Full Text Available The reinforced concrete with fiber reinforced polymer (FRP bars (carbon, aramid, basalt and glass is used in places where a high ratio of strength to weight is required and corrosion is not acceptable. Behavior of structural members using (FRP bars is hard to be modeled using traditional methods because of the high non-linearity relationship among factors influencing the strength of structural members. Back-propagation neural network is a very effective method for modeling such complicated relationships. In this paper, back-propagation neural network is used for modeling the flexural behavior of beams reinforced with (FRP bars. 101 samples of beams reinforced with fiber bars were collected from literatures. Five important factors are taken in consideration for predicting the strength of beams. Two models of Multilayer Perceptron (MLP are created, first with single-hidden layer and the second with two-hidden layers. The two-hidden layer model showed better accuracy ratio than the single-hidden layer model. Parametric study has been done for two-hidden layer model only. Equations are derived to be used instead of the model and the importance of input factors is determined. Results showed that the neural network is successful in modeling the behavior of concrete beams reinforced with different types of (FRP bars.

An evaluation of resistance to change with unconditioned and conditioned reinforcers.

Science.gov (United States)

Vargo, Kristina K; Ringdahl, Joel E

2015-09-01

Several reinforcer-related variables influence a response's resistance to change (Nevin, 1974). Reinforcer type (i.e., conditioned or unconditioned) is a reinforcer-related variable that has not been studied with humans but may have clinical implications. In Experiment 1, we identified unconditioned and conditioned reinforcers of equal preference. In Experiments 2, 3, and 4, we reinforced participants' behavior during a baseline phase using a multiple variable-interval (VI) 30-s VI 30-s schedule with either conditioned (i.e., token) or unconditioned (i.e., food; one type of reinforcement in each component) reinforcement. After equal reinforcement rates across components, we introduced a disruptor. Results of Experiments 2 and 3 showed that behaviors were more resistant to extinction and distraction, respectively, with conditioned than with unconditioned reinforcers. Results of Experiment 4, however, showed that when prefeeding disrupted responding, behaviors were more resistant to change with unconditioned reinforcers than with conditioned reinforcers. © Society for the Experimental Analysis of Behavior.

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.

Mechanical Properties of Welded Deformed Reinforcing Steel Bars

Directory of Open Access Journals (Sweden)

Ghafur H. Ahmed

2015-05-01

Full Text Available Reinforcement strength, ductility and bendability properties are important components in design of reinforced concrete members, as the strength of any member comes mainly from reinforcement. Strain compatibility and plastic behaviors are mainly depending on reinforcement ductility. In construction practice, often welding of the bars is required. Welding of reinforcement is an instant solution in many cases, whereas welding is not a routine connection process. Welding will cause deficiencies in reinforcement bars, metallurgical changes and re-crystallization of microstructure of particles. Weld metal toughness is extremely sensitive to the welding heat input that decreases both of its strength and ductility. For determining the effects of welding in reinforcement properties, 48 specimens were tested with 5 different bar diameters, divided into six groups. Investigated parameters were: properties of un-welded bars; strength, ductility and density of weld metal; strength and ductility reduction due to heat input for bundled bars and transverse bars; welding effect on bars’ bending properties; behavior of different joint types; properties of three weld groove shapes also the locations and types of failures sections. Results show that, strength and elongation of the welded bars decreased by (10-40% and (30-60% respectively. Cold bending of welded bars and groove welds shall be prevented.

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.

Deep Reinforcement Learning: An Overview

OpenAIRE

Li, Yuxi

2017-01-01

We give an overview of recent exciting achievements of deep reinforcement learning (RL). We discuss six core elements, six important mechanisms, and twelve applications. We start with background of machine learning, deep learning and reinforcement learning. Next we discuss core RL elements, including value function, in particular, Deep Q-Network (DQN), policy, reward, model, planning, and exploration. After that, we discuss important mechanisms for RL, including attention and memory, unsuperv...

Response-reinforcer dependency and resistance to change.

Science.gov (United States)

Cançado, Carlos R X; Abreu-Rodrigues, Josele; Aló, Raquel Moreira; Hauck, Flávia; Doughty, Adam H

2018-01-01

The effects of the response-reinforcer dependency on resistance to change were studied in three experiments with rats. In Experiment 1, lever pressing produced reinforcers at similar rates after variable interreinforcer intervals in each component of a two-component multiple schedule. Across conditions, in the fixed component, all reinforcers were response-dependent; in the alternative component, the percentage of response-dependent reinforcers was 100, 50 (i.e., 50% response-dependent and 50% response-independent) or 10% (i.e., 10% response-dependent and 90% response-independent). Resistance to extinction was greater in the alternative than in the fixed component when the dependency in the former was 10%, but was similar between components when this dependency was 100 or 50%. In Experiment 2, a three-component multiple schedule was used. The dependency was 100% in one component and 10% in the other two. The 10% components differed on how reinforcers were programmed. In one component, as in Experiment 1, a reinforcer had to be collected before the scheduling of other response-dependent or independent reinforcers. In the other component, response-dependent and -independent reinforcers were programmed by superimposing a variable-time schedule on an independent variable-interval schedule. Regardless of the procedure used to program the dependency, resistance to extinction was greater in the 10% components than in the 100% component. These results were replicated in Experiment 3 in which, instead of extinction, VT schedules replaced the baseline schedules in each multiple-schedule component during the test. We argue that the relative change in dependency from Baseline to Test, which is greater when baseline dependencies are high rather than low, could account for the differential resistance to change in the present experiments. The inconsistencies in results across the present and previous experiments suggest that the effects of dependency on resistance to change are

Durability of fibre reinforced concrete structures

DEFF Research Database (Denmark)

Hansen, Ernst Jan De Place; Hansen, Kurt Kielsgaard

1996-01-01

The planned research will indicate, whether fibre reinforced concrete has better or worse durability than normal concrete. Durability specimens will be measured on cracked as well as uncracked specimens. Also the pore structure in the concrete will be characterized.Keywords: Fibre reinforced...... concrete, durability, pore structure, mechanical load...

Behavior of reinforced concrete at elevated temperatures

International Nuclear Information System (INIS)

Freskakis, G.N.

1984-09-01

A study is presented concerning the behavior of reinforced concrete sections at elevated temperatures. Material properties of concrete and reinforcing steel are discussed. Behavior studies are made by means of moment-curvature-axial force relationships. Particular attention is given to the load carrying capacity, thermal forces and moments, and deformation capacity. The effects on these properties of variations in the strength properties, the temperature level and distribution, the amount of reinforcing steel, and limiting values of strains are considered

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...

Experimental investigation of the relation between damage at the concrete-steel interface and initiation of reinforcement corrosion in plain and fibre reinforced concrete

International Nuclear Information System (INIS)

Michel, A.; Solgaard, A.O.S.; Pease, B.J.; Geiker, M.R.; Stang, H.; Olesen, J.F.

2013-01-01

Highlights: •Cracked plain and steel fibre reinforced concrete flexural beams were investigated. •“Instrumented rebars” provided location- and time-dependent corrosion measurements. •Interfacial condition can be used as a reliable indicator to quantify the risk of corrosion. •Simulated interfacial conditions are in very good agreement with all experimental observations. -- Abstract: Cracks in covering concrete are known to hasten initiation of steel corrosion in reinforced concrete structures. To minimise the impact of cracks on the deterioration of reinforced concrete structures, current approaches in (inter)national design codes often limit the concrete surface crack width. Recent investigations however, indicate that the concrete-reinforcement interfacial condition is a more fundamental criterion related to reinforcement corrosion. This work investigates the relation between macroscopic damage at the concrete-steel interface and corrosion initiation of reinforcement embedded in plain and fibre reinforced concrete. Comparisons of experimental and numerical results indicate a strong correlation between corrosion initiation and interfacial condition

Origins of altered reinforcement effects in ADHD

Directory of Open Access Journals (Sweden)

Tripp Gail

2009-02-01

Full Text Available Abstract Attention-deficit/hyperactivity disorder (ADHD, characterized by hyperactivity, impulsiveness and deficient sustained attention, is one of the most common and persistent behavioral disorders of childhood. ADHD is associated with catecholamine dysfunction. The catecholamines are important for response selection and memory formation, and dopamine in particular is important for reinforcement of successful behavior. The convergence of dopaminergic mesolimbic and glutamatergic corticostriatal synapses upon individual neostriatal neurons provides a favorable substrate for a three-factor synaptic modification rule underlying acquisition of associations between stimuli in a particular context, responses, and reinforcers. The change in associative strength as a function of delay between key stimuli or responses, and reinforcement, is known as the delay of reinforcement gradient. The gradient is altered by vicissitudes of attention, intrusions of irrelevant events, lapses of memory, and fluctuations in dopamine function. Theoretical and experimental analyses of these moderating factors will help to determine just how reinforcement processes are altered in ADHD. Such analyses can only help to improve treatment strategies for ADHD.

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.

Synergistic effects of mica and wollastonite fillers on thermal performance of intumescent fire retardant coating

Energy Technology Data Exchange (ETDEWEB)

Zia-ul-Mustafa, M., E-mail: engr.ziamustafa@gmail.com; Ahmad, Faiz; Megat-Yusoff, Puteri S. M.; Aziz, Hammad [Mechanical Engineering Department, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia)

2015-07-22

In this study, intumescent fire retardant coatings (IFRC) were developed to investigate the synergistic effects of reinforced mica and wollastonite fillers based IFRC towards heat shielding, char expansion, char composition and char morphology. Ammonium poly-phosphate (APP) was used as acid source, expandable graphite (EG) as carbon source, melamine as blowing agent, boric acid as additive and Hardener H-2310 polyamide amine in bisphenol A epoxy resin BE-188(BPA) was used as curing agent. Bunsen burner fire test was used for thermal performance according to UL-94 for 1 h. Field Emission Scanning Electron Microscopy (FESEM) was used to observe char microstructure. X-Ray Diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to analyse char composition. The results showed that addition of clay filler in IFRC enhanced the fire protection performance of intumescent coating. X-Ray Diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) results showed the presence of boron phosphate, silicon phosphate oxide, aluminium borate in the char that improved the thermal performance of intumescent fire retardant coating (IFRC). Resultantly, the presence of these developed compounds enhanced the Integrity of structural steel upto 500°C.

Numerical modelling of reinforced concrete beams with fracture-plastic material

Directory of Open Access Journals (Sweden)

O. Sucharda

2014-10-01

Full Text Available This paper describes the use of models of fracture-plastic materials for reinforced concrete in numerical modelling of beams made from reinforced concrete. The purpose of the paper is to use of a model of concrete for modelling of a behaviour of reinforced concrete beams which have been tested at the University of Toronto within re-examination of classic concrete beam tests. The original tests were performed by Bresler- Scordelis. A stochastic modelling based on LHS (Latin Hypercube Sampling has been performed for the reinforced concrete beam. An objective of the modelling is to evaluate the total bearing capacity of the reinforced concrete beams depending on distribution of input data. The beams from the studied set have longitudinal reinforcement only. The beams do not have any shear reinforcement. The software used for the fracture-plastic model of the reinforced concrete is the ATENA.

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.

Reinforcement learning in supply chains.

Science.gov (United States)

Valluri, Annapurna; North, Michael J; Macal, Charles M

2009-10-01

Effective management of supply chains creates value and can strategically position companies. In practice, human beings have been found to be both surprisingly successful and disappointingly inept at managing supply chains. The related fields of cognitive psychology and artificial intelligence have postulated a variety of potential mechanisms to explain this behavior. One of the leading candidates is reinforcement learning. This paper applies agent-based modeling to investigate the comparative behavioral consequences of three simple reinforcement learning algorithms in a multi-stage supply chain. For the first time, our findings show that the specific algorithm that is employed can have dramatic effects on the results obtained. Reinforcement learning is found to be valuable in multi-stage supply chains with several learning agents, as independent agents can learn to coordinate their behavior. However, learning in multi-stage supply chains using these postulated approaches from cognitive psychology and artificial intelligence take extremely long time periods to achieve stability which raises questions about their ability to explain behavior in real supply chains. The fact that it takes thousands of periods for agents to learn in this simple multi-agent setting provides new evidence that real world decision makers are unlikely to be using strict reinforcement learning in practice.

Rotational Capacity of Reinforced Concrete Beams

DEFF Research Database (Denmark)

Ulfkjær, J. P.; Henriksen, M. S.; Brincker, Rune

1995-01-01

programme where 120 reinforced concrete beams, 54 plain concrete beams and 324 concrete cylinders are tested. For the reinforced concrete beams four different parar meters are varied. The slenderness is 6, 12 and 18, the beam depth is 100 mm, 200 mm and 400 mm giving nine different geometries, five...

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

Directory of Open Access Journals (Sweden)

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...

GLASS-FIBRE REINFORCED COMPOSITES: THE EFFECT OF ...

African Journals Online (AJOL)

HOD

mechanical and corrosion wear behaviour of any reinforced composites. In other ..... physical properties of glass fibre reinforced epoxy resin and the following .... waste in concrete and cement composites," Journal of Cleaner Production, vol.

Farmacogenómica: Aplicaciones cardiovasculares

Directory of Open Access Journals (Sweden)

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

Directory of Open Access Journals (Sweden)

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.

Human choice among five alternatives when reinforcers decay.

Science.gov (United States)

Rothstein, Jacob B; Jensen, Greg; Neuringer, Allen

2008-06-01

Human participants played a computer game in which choices among five alternatives were concurrently reinforced according to dependent random-ratio schedules. "Dependent" indicates that choices to any of the wedges activated the random-number generators governing reinforcers on all five alternatives. Two conditions were compared. In the hold condition, once scheduled, a reinforcer - worth a constant five points - remained available until it was collected. In the decay condition, point values decreased with intervening responses, i.e., rapid collection was differentially reinforced. Slopes of matching functions were higher in the decay than hold condition. However inter-subject variability was high in both conditions.

Toughened microstructures for ductile phase reinforced molybdenum disilicide

International Nuclear Information System (INIS)

Pickard, S.M.; Ghosh, A.K.

1995-01-01

Various morphologies of ductile Nb refractory metal reinforcement are incorporated into a MoSi 2 matrix using powder metallurgy, including single-ply laminates, continuous metal ribbons and sections of 2-dimensional wire mesh. Hot forging techniques are used to redistribute the reinforcement and change the dimensions and the aspect ratio of the reinforcing metal ligaments. Work-of-rupture measurements are conducted on bend test specimens and precracked tensile specimens of the composite so that the toughness contribution from the various ductile metal morphologies can be assessed according to its effectiveness. Accompanying microstructural examination of crack bridging interaction with the reinforcement is conducted

Generating variable and random schedules of reinforcement using Microsoft Excel macros.

Science.gov (United States)

Bancroft, Stacie L; Bourret, Jason C

2008-01-01

Variable reinforcement schedules are used to arrange the availability of reinforcement following varying response ratios or intervals of time. Random reinforcement schedules are subtypes of variable reinforcement schedules that can be used to arrange the availability of reinforcement at a constant probability across number of responses or time. Generating schedule values for variable and random reinforcement schedules can be difficult. The present article describes the steps necessary to write macros in Microsoft Excel that will generate variable-ratio, variable-interval, variable-time, random-ratio, random-interval, and random-time reinforcement schedule values.

Evaluation of the protection behaviour of reinforcement steel against corrosion induced by chlorides in reinforced mortar specimens

International Nuclear Information System (INIS)

Crivelaro, Marcos

2002-01-01

In this work various treatments for protecting reinforcing steels against corrosion induced by chlorides have been evaluated. Additives to mortars and surface treatments given to reinforcing steels were evaluated as corrosion protection measures. In the preliminary tests the corrosion resistance of a CA 50 steel treated by immersion in nearly 50 different solutions, was determined. The solutions were prepared with tannins (from various sources) and/or benzotriazole, and during immersion, a surface film formed on the steel. The corrosion resistance of the coated steels was evaluated in a saturated Ca(OH) 2 solution with 5% (wt) NaCl. Preliminary tests were also carried out with mortars reinforced with uncoated steel to which tannin or lignin was added. Two organic coatings, a monocomponent and a bicomponent type, formulated specially for this investigation, with both tannin and benzotriazole, were also tested in the preliminary tests to select the coating with better corrosion protection property. The bicomponent type (epoxy coating) showed better performance than the monocomponent type coating, and the former was therefore chosen to investigate the corrosion performance on CA 50 steel inside mortar specimens. From the preliminary tests, two solutions with tannin from two sources, Black Wattle (Acacia mearnsii) and Brazilian tea (Ilex paraguariensis St. Hill), to which benzotriazole and phosphoric acid were added, were chosen. Mortar specimens reinforced with CA50 steel treated by immersion in these two solutions were prepared. Also, epoxy coated CA50 steel was tested as reinforcement inside mortar specimens. Mortars reinforced with uncoated CA50 steel were also prepared and corrosion tested for comparison. The effect of tannin and lignin as separate additives to the mortar on the corrosion resistance of uncoated steel was also studied. The reinforced mortar specimens were tested with various cycles of immersion for 2 days in 3.5% (wt) NaCl followed by with air

[The behavior of fiber-reinforced plastics during laser cutting].

Science.gov (United States)

Emmrich, M; Levsen, K; Trasser, F J

1992-06-01

The pattern of the organic emissions, which are produced by processing of fibre reinforced plastics (epoxy resins reinforced by aramid and glass fibres and phenol resins reinforced by aramid fibre) with laser beam was studied and the concentrations of the main components determined. Despite the application of plastic materials with different chemical structures, the observed patterns are very similar. Mainly aromatic hydrocarbons are emitted, especially benzene and toluene, as well as some heteroatom-containing aromatic hydrocarbons (e.g. phenol). By use of oxygen as process gas the emissions during cutting of glass fibre reinforced plastics can be reduced, while they will be constantly high with aramid fibre reinforced plastics.

Generating Variable and Random Schedules of Reinforcement Using Microsoft Excel Macros

Science.gov (United States)

Bancroft, Stacie L.; Bourret, Jason C.

2008-01-01

Variable reinforcement schedules are used to arrange the availability of reinforcement following varying response ratios or intervals of time. Random reinforcement schedules are subtypes of variable reinforcement schedules that can be used to arrange the availability of reinforcement at a constant probability across number of responses or time.…

Antropología Económica: una Reseña Introductoria

Directory of Open Access Journals (Sweden)

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

Effect of the reinforcement bar arrangement on the efficiency of electrochemical chloride removal technique applied to reinforced concrete structures

International Nuclear Information System (INIS)

Garces, P.; Sanchez de Rojas, M.J.; Climent, M.A.

2006-01-01

This paper reports on the research done to find out the effect that different bar arrangements may have on the efficiency of the electrochemical chloride removal (ECR) technique when applied to a reinforced concrete structural member. Five different types of bar arrangements were considered, corresponding to typical structural members such as columns (with single and double bar reinforcing), slabs, beams and footings. ECR was applied in several steps. We observe that the extraction efficiency depends on the reinforcing bar arrangement. A uniform layer set-up favours chloride extraction. Electrochemical techniques were also used to estimate the reinforcing bar corrosion states, as well as measure the corrosion potential, and instant corrosion rate based on the polarization resistance technique. After ECR treatment, a reduction in the corrosion levels is observed falling short of the depassivation threshold

Reinforcement versus fluidization in cytoskeletal mechanoresponsiveness.

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Ramaswamy Krishnan

Full Text Available Every adherent eukaryotic cell exerts appreciable traction forces upon its substrate. Moreover, every resident cell within the heart, great vessels, bladder, gut or lung routinely experiences large periodic stretches. As an acute response to such stretches the cytoskeleton can stiffen, increase traction forces and reinforce, as reported by some, or can soften and fluidize, as reported more recently by our laboratory, but in any given circumstance it remains unknown which response might prevail or why. Using a novel nanotechnology, we show here that in loading conditions expected in most physiological circumstances the localized reinforcement response fails to scale up to the level of homogeneous cell stretch; fluidization trumps reinforcement. Whereas the reinforcement response is known to be mediated by upstream mechanosensing and downstream signaling, results presented here show the fluidization response to be altogether novel: it is a direct physical effect of mechanical force acting upon a structural lattice that is soft and fragile. Cytoskeletal softness and fragility, we argue, is consistent with early evolutionary adaptations of the eukaryotic cell to material properties of a soft inert microenvironment.

Introduction to Concrete Reinforcing. Instructor Edition. Introduction to Construction Series.

Science.gov (United States)

Oklahoma State Dept. of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

This module on concrete reinforcing is one of a series of modules designed to teach basic skills necessary for entry-level employment in this field. This module contains three instructional units that cover the following topics: (1) concrete reinforcing materials; (2) concrete reinforcing tools; and (3) concrete reinforcing basic skills. Each…

CARACTERIZAÇÃO ANATÔMICA E HISTOQUÍMICA DAS FOLHAS DE EUGENIA UNIFLORA L.

Directory of Open Access Journals (Sweden)

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

Directory of Open Access Journals (Sweden)

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.

Behaviour of fibre reinforced polymer confined reinforced concrete columns under fire condition

Science.gov (United States)

Chowdhury, Ershad Ullah

In recent years, fibre reinforced polymer (FRP) materials have demonstrated enormous potential as materials for repairing and retrofitting concrete bridges that have deteriorated from factors such as electro-chemical corrosion and increased load requirements. However, concerns associated with fire remain an obstacle to applications of FRP materials in buildings and parking garages due to FRP's sensitivity to high temperatures as compared with other structural materials and to limited knowledge on their thermal and mechanical behaviour in fire. This thesis presents results from an ongoing study on the fire performance of FRP materials, fire insulation materials and systems, and FRP wrapped reinforced concrete columns. The overall goal of the study is to understand the fire behaviour of FRP materials and FRP strengthened concrete columns and ultimately, provide rational fire safety design recommendations and guidelines for FRP strengthened concrete columns. A combined experimental and numerical investigation was conducted to achieve the goals of this research study. The experimental work consisted of both small-scale FRP material testing at elevated temperatures and full-scale fire tests on FRP strengthened columns. A numerical model was developed to simulate the behaviour of unwrapped reinforced concrete and FRP strengthened reinforced concrete square or rectangular columns in fire. After validating the numerical model against test data available in literature, it was determined that the numerical model can be used to analyze the behaviour of concrete axial compressive members in fire. Results from this study also demonstrated that although FRP materials experience considerable loss of their mechanical and bond properties at temperatures somewhat below the glass transition temperature of the resin matrix, externally-bonded FRP can be used in strengthening concrete structural members in buildings, if appropriate supplemental fire protection system is provided over

Equivalence relations and the reinforcement contingency.

Science.gov (United States)

Sidman, M

2000-07-01

Where do equivalence relations come from? One possible answer is that they arise directly from the reinforcement contingency. That is to say, a reinforcement contingency produces two types of outcome: (a) 2-, 3-, 4-, 5-, or n-term units of analysis that are known, respectively, as operant reinforcement, simple discrimination, conditional discrimination, second-order conditional discrimination, and so on; and (b) equivalence relations that consist of ordered pairs of all positive elements that participate in the contingency. This conception of the origin of equivalence relations leads to a number of new and verifiable ways of conceptualizing equivalence relations and, more generally, the stimulus control of operant behavior. The theory is also capable of experimental disproof.

Slipforming of reinforced concrete shield building

International Nuclear Information System (INIS)

Hsieh, M.C.; King, J.R.

1982-01-01

The unique design and construction features of slipforming the heavily reinforced concrete cylindrical shield walls at the Satsop nuclear plant in Washington, D.C. site are presented. The shield walls were designed in compliance with seismic requirements which resulted in the need for reinforcing steel averaging 326 kg/m/sup 3/. A 7.6 m high, three-deck moving platform was designed to permit easy installation of the reinforcing steel, embedments, and blockouts, and to facilitate concrete placement and finishing. Two circular box trusses, one on each side of the shield wall, were used in combination with a spider truss to meet both the tolerance and strength requirements for the slipform assembly

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

Quantitative radiographic analysis of fiber reinforced polymer composites.

Science.gov (United States)

Baidya, K P; Ramakrishna, S; Rahman, M; Ritchie, A

2001-01-01

X-ray radiographic examination of the bone fracture healing process is a widely used method in the treatment and management of patients. Medical devices made of metallic alloys reportedly produce considerable artifacts that make the interpretation of radiographs difficult. Fiber reinforced polymer composite materials have been proposed to replace metallic alloys in certain medical devices because of their radiolucency, light weight, and tailorable mechanical properties. The primary objective of this paper is to provide a comparable radiographic analysis of different fiber reinforced polymer composites that are considered suitable for biomedical applications. Composite materials investigated consist of glass, aramid (Kevlar-29), and carbon reinforcement fibers, and epoxy and polyether-ether-ketone (PEEK) matrices. The total mass attenuation coefficient of each material was measured using clinical X-rays (50 kev). The carbon fiber reinforced composites were found to be more radiolucent than the glass and kevlar fiber reinforced composites.

Behavior of reinforcement SCC beams under elevated temperatures

Science.gov (United States)

Fathi, Hamoon; Farhang, Kianoosh

2015-09-01

This experimental study focuses on the behavior of heated reinforced concrete beams. Four types of concrete mixtures were used for the tested self-compacting concrete beams. A total of 72 reinforced concrete beams and 72 standard cylindrical specimens were tested. The compressive strength under uniaxial loading at 23 °C ranged from 30 to 45 MPa. The specimens were exposed to different temperatures. The test parameters of interest were the compressive strength and the temperature of the specimens. The effect of changes in the parameters was examined so as to control the behavior of the tested concrete and that of the reinforced concrete beam. The results indicated that flexibility and compressive strength of the reinforced concrete beams decreased at higher temperatures. Furthermore, heating beyond 400 °C produced greater variations in the structural behavior of the materials in both the cylindrical samples and the reinforced concrete beams.

Vicarious Reinforcement In Rhesus Macaques (Macaca mulatta

Directory of Open Access Journals (Sweden)

Steve W. C. Chang

2011-03-01

Full Text Available What happens to others profoundly influences our own behavior. Such other-regarding outcomes can drive observational learning, as well as motivate cooperation, charity, empathy, and even spite. Vicarious reinforcement may serve as one of the critical mechanisms mediating the influence of other-regarding outcomes on behavior and decision-making in groups. Here we show that rhesus macaques spontaneously derive vicarious reinforcement from observing rewards given to another monkey, and that this reinforcement can motivate them to subsequently deliver or withhold rewards from the other animal. We exploited Pavlovian and instrumental conditioning to associate rewards to self (M1 and/or rewards to another monkey (M2 with visual cues. M1s made more errors in the instrumental trials when cues predicted reward to M2 compared to when cues predicted reward to M1, but made even more errors when cues predicted reward to no one. In subsequent preference tests between pairs of conditioned cues, M1s preferred cues paired with reward to M2 over cues paired with reward to no one. By contrast, M1s preferred cues paired with reward to self over cues paired with reward to both monkeys simultaneously. Rates of attention to M2 strongly predicted the strength and valence of vicarious reinforcement. These patterns of behavior, which were absent in nonsocial control trials, are consistent with vicarious reinforcement based upon sensitivity to observed, or counterfactual, outcomes with respect to another individual. Vicarious reward may play a critical role in shaping cooperation and competition, as well as motivating observational learning and group coordination in rhesus macaques, much as it does in humans. We propose that vicarious reinforcement signals mediate these behaviors via homologous neural circuits involved in reinforcement learning and decision-making.

Vicarious reinforcement in rhesus macaques (macaca mulatta).

Science.gov (United States)

Chang, Steve W C; Winecoff, Amy A; Platt, Michael L

2011-01-01

What happens to others profoundly influences our own behavior. Such other-regarding outcomes can drive observational learning, as well as motivate cooperation, charity, empathy, and even spite. Vicarious reinforcement may serve as one of the critical mechanisms mediating the influence of other-regarding outcomes on behavior and decision-making in groups. Here we show that rhesus macaques spontaneously derive vicarious reinforcement from observing rewards given to another monkey, and that this reinforcement can motivate them to subsequently deliver or withhold rewards from the other animal. We exploited Pavlovian and instrumental conditioning to associate rewards to self (M1) and/or rewards to another monkey (M2) with visual cues. M1s made more errors in the instrumental trials when cues predicted reward to M2 compared to when cues predicted reward to M1, but made even more errors when cues predicted reward to no one. In subsequent preference tests between pairs of conditioned cues, M1s preferred cues paired with reward to M2 over cues paired with reward to no one. By contrast, M1s preferred cues paired with reward to self over cues paired with reward to both monkeys simultaneously. Rates of attention to M2 strongly predicted the strength and valence of vicarious reinforcement. These patterns of behavior, which were absent in non-social control trials, are consistent with vicarious reinforcement based upon sensitivity to observed, or counterfactual, outcomes with respect to another individual. Vicarious reward may play a critical role in shaping cooperation and competition, as well as motivating observational learning and group coordination in rhesus macaques, much as it does in humans. We propose that vicarious reinforcement signals mediate these behaviors via homologous neural circuits involved in reinforcement learning and decision-making.

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” ...

Structural performance evaluation on aging underground reinforced concrete structures. Part 5

International Nuclear Information System (INIS)

Matsumura, Takuro; Matsuo, Toyofumi; Miyagawa, Yoshinori

2009-01-01

When we evaluate the soundness of reinforced concrete structures, it is important to assess the chloride induced deterioration. We conducted the reinforcing steel corrosion tests of reinforced concrete specimens under simulated tidal environment of sea. Parameters of the tests were water cement ratio, cement type and crack width of concrete. Periods of the tests were eighty month. The obtained results were summarized at follows: (a) The chloride ion concentration at the initiation of reinforcing steel corrosion was about 3.0 kg/m 3 in case of reinforcing steel in non-crack concrete used ordinary cement. (b) The corrosion rate of reinforcing steels was almost constant at any cement type specimens after causing crack by reinforcing steel corrosion. (c) The corrosion rate of reinforcing steels in specimens, which caused cracks by bending load, increased as crack width. In the same type specimens, the corrosion rate of reinforcing steels in fly ash cement specimens was larger than that of ordinary cement specimens. In this case, the corrosion rate of reinforcing steels was evaluated about 0.18 mm/year. (author)

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

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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.

Disperse reinforced concrete used in obtaining prefabricated elements for roads

Directory of Open Access Journals (Sweden)

Bogdan MEZEI

2014-07-01

Full Text Available Concrete is the most used material in construction. By improving the performance of materials and of technologies, concretes with outstanding performances were also developed, in the past two decades. Concrete with dispersed reinforcement represents a new generation of reinforced concrete that combines a good behavior of concrete compressive strength with an increased tensile strength of steel fibers. Using this material, monolithic and prefabricated concrete elements with high mechanical strengths and high durability can be obtained. Technological processes for preparation of concrete with dispersed reinforcement are similar to the conventional methods and do not involve using additional equipment for dosing the dispersed reinforcement. The study aimed the development of road plates made with optimized disperse- reinforced concrete. The first tests were done on plates from the gutter roadway, having a classic reinforcement, using different percentages of fibre reinforcement in the concrete composition, leading to the development of a new optimized economical solution. The results prove the enhanced characteristics of the disperse-reinforced concrete versus conventional concrete, and hence of the developed concrete plates.

Global reinforcement training of CrossNets

Science.gov (United States)

Ma, Xiaolong

2007-10-01

Hybrid "CMOL" integrated circuits, incorporating advanced CMOS devices for neural cell bodies, nanowires as axons and dendrites, and latching switches as synapses, may be used for the hardware implementation of extremely dense (107 cells and 1012 synapses per cm2) neuromorphic networks, operating up to 10 6 times faster than their biological prototypes. We are exploring several "Cross- Net" architectures that accommodate the limitations imposed by CMOL hardware and should allow effective training of the networks without a direct external access to individual synapses. Our studies have show that CrossNets based on simple (two-terminal) crosspoint devices can work well in at least two modes: as Hop-field networks for associative memory and multilayer perceptrons for classification tasks. For more intelligent tasks (such as robot motion control or complex games), which do not have "examples" for supervised learning, more advanced training methods such as the global reinforcement learning are necessary. For application of global reinforcement training algorithms to CrossNets, we have extended Williams's REINFORCE learning principle to a more general framework and derived several learning rules that are more suitable for CrossNet hardware implementation. The results of numerical experiments have shown that these new learning rules can work well for both classification tasks and reinforcement tasks such as the cartpole balancing control problem. Some limitations imposed by the CMOL hardware need to be carefully addressed for the the successful application of in situ reinforcement training to CrossNets.

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...

Strengthening of the Timber Members Using Fibre Reinforced Polymer Composites

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Ioana-Sorina Enţuc

2004-01-01

Full Text Available The reinforcement of structural wood products has become in the last decades an efficient method of improving structural capabilities of load carrying members made of this material. Some important steps in earlier stages of research were focused on using metallic reinforcement, including steel bars, prestressed stranded cables, and bonded steel and aluminum plates. A disadvantage of the metallic reinforcement was the poor compatibility between the wood and the reinforcing materials. In comparison with metallic reinforcement, fiber reinforced polymers (FRP composites are compatible with structural wood products leading to efficient hybrid members. Some interesting strengthening alternatives using FRP applied to wood beams and to wood columns are presented in this paper.

Bond characteristics of steel fiber and deformed reinforcing steel bar embedded in steel fiber reinforced self-compacting concrete (SFRSCC)

Science.gov (United States)

Aslani, Farhad; Nejadi, Shami

2012-09-01

Steel fiber reinforced self-compacting concrete (SFRSCC) is a relatively new composite material which congregates the benefits of the self-compacting concrete (SCC) technology with the profits derived from the fiber addition to a brittle cementitious matrix. Steel fibers improve many of the properties of SCC elements including tensile strength, ductility, toughness, energy absorption capacity, fracture toughness and cracking. Although the available research regarding the influence of steel fibers on the properties of SFRSCC is limited, this paper investigates the bond characteristics between steel fiber and SCC firstly. Based on the available experimental results, the current analytical steel fiber pullout model (Dubey 1999) is modified by considering the different SCC properties and different fiber types (smooth, hooked) and inclination. In order to take into account the effect of fiber inclination in the pullout model, apparent shear strengths ( τ ( app)) and slip coefficient ( β) are incorporated to express the variation of pullout peak load and the augmentation of peak slip as the inclined angle increases. These variables are expressed as functions of the inclined angle ( ϕ). Furthurmore, steel-concrete composite floors, reinforced concrete floors supported by columns or walls and floors on an elastic foundations belong to the category of structural elements in which the conventional steel reinforcement can be partially replaced by the use of steel fibers. When discussing deformation capacity of structural elements or civil engineering structures manufactured using SFRSCC, one must be able to describe thoroughly both the behavior of the concrete matrix reinforced with steel fibers and the interaction between this composite matrix and discrete steel reinforcement of the conventional type. However, even though the knowledge on bond behavior is essential for evaluating the overall behavior of structural components containing reinforcement and steel fibers

Soil reinforcement with geosynthetics

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Bessaim Mohammed Mustapha

2018-01-01

Full Text Available The proportionality of existence of land with good bearing to erect any building or building is very small, to remedy this deficiency it is necessary to resort to techniques of reinforcement of the soils which can constitute a very important development. Among these methods of remediation, there is reinforcement by the geosynthetics which constitute an effective solution to these constraints. This process tends to stabilize the soil in question with increased load bearing capacity in civil engineering and geotechnical works such as embankments, slopes, embankments and hydraulic structures, with an inestimable gain in time, economy and durability while preserving the natural and environmental aspect.

La industria cerámica brasileña

Directory of Open Access Journals (Sweden)

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

Surface Heave Behaviour of Coir Geotextile Reinforced Sand Beds

Science.gov (United States)

Lal, Dharmesh; Sankar, N.; Chandrakaran, S.

2017-06-01

Soil reinforcement by natural fibers is one of the cheapest and attractive ground improvement techniques. Coir is the most abundant natural fiber available in India and due to its high lignin content; it has a larger life span than other natural fibers. It is widely used in India for erosion control purposes, but its use as a reinforcement material is rather limited. This study focuses on the use of coir geotextile as a reinforcement material to reduce surface heave phenomena occurring in shallow foundations. This paper presents the results of laboratory model tests carried out on square footings supported on coir geotextile reinforced sand beds. The influence of various parameters such as depth of reinforcement, length, and number of layers of reinforcement was studied. It was observed that surface heave is considerably reduced with the provision of geotextile. Heave reduction up to 98.7% can be obtained by the proposed method. Heave reduction is quantified by a non-dimensional parameter called heave reduction factor.

Neurofeedback in Learning Disabled Children: Visual versus Auditory Reinforcement.

Science.gov (United States)

Fernández, Thalía; Bosch-Bayard, Jorge; Harmony, Thalía; Caballero, María I; Díaz-Comas, Lourdes; Galán, Lídice; Ricardo-Garcell, Josefina; Aubert, Eduardo; Otero-Ojeda, Gloria

2016-03-01

Children with learning disabilities (LD) frequently have an EEG characterized by an excess of theta and a deficit of alpha activities. NFB using an auditory stimulus as reinforcer has proven to be a useful tool to treat LD children by positively reinforcing decreases of the theta/alpha ratio. The aim of the present study was to optimize the NFB procedure by comparing the efficacy of visual (with eyes open) versus auditory (with eyes closed) reinforcers. Twenty LD children with an abnormally high theta/alpha ratio were randomly assigned to the Auditory or the Visual group, where a 500 Hz tone or a visual stimulus (a white square), respectively, was used as a positive reinforcer when the value of the theta/alpha ratio was reduced. Both groups had signs consistent with EEG maturation, but only the Auditory Group showed behavioral/cognitive improvements. In conclusion, the auditory reinforcer was more efficacious in reducing the theta/alpha ratio, and it improved the cognitive abilities more than the visual reinforcer.

Corrosión of reinforcements in reinforced and prestressed concretes. II part

Directory of Open Access Journals (Sweden)

Calleja, J.

1966-12-01

Full Text Available Not availableDentro del capítulo general de la "durabilidad" o resistencia química en el tiempo de lm; conglomerados hidráulicos (morteros y hormigones armados y pretensados, el apartado relativo a la "corrosión" de las armaduras ocupa un lugar preponderante por su importancia técnica y económica. Esta importancia va siendo reconocida cada día más, a pesar de ser (o de haber sido el de la corrosión uno de los temas menos familiares en el ámbito de la construcción. La razón estriba en la fuerza de los hechos, y se manifiesta con claridad en las tareas encomendadas y en los problemas presentados a los laboratorios de investigación y ensayos de materiales. La corrosión es un fenómeno fisicoquímico que cae dentro del dominio de la ELECTROQUIMICA y que debe estudiarse y enjuiciarse con arreglo a las leyes fundamentales de esta disciplina. Lo mismo cabe decir por lo que respecta a los métodos de "protección" contra la corrosión. La corrosión es un "riesgo" aleatorio que se corre y contra el que hay que prevenirse mediante un "seguro", representado por dichas medidas de protección. El remedio "más fácil" desde un punto de vista técnico, y "más barato" desde un punto de vista "económico", es siempre de carácter "preventivo" antes que "curativo", es decir, es el tomado ya en la etapa de proyecto de la obra o estructura de que se trate. En el caso del hormigón, la mejor protección de las armaduras la da, en primer lugar, la aplicación de un "código de buena práctica" a la elaboración del material y a la ejecución de la obra, y, en segundo lugar, la observancia de los más elementales principios de la Electroquímica en el aspecto de la corrosión. La utilización de aditivos acelerantes de fraguado y endurecimiento con naturaleza "clorurada" y el estado de "tensión" de las armaduras son aspectos que merecen especial consideración, así como las posibles acciones electroquímicas debidas a "corrientes vagabundas" a trav

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

Directory of Open Access Journals (Sweden)

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.

Tensile behavior and tension stiffening of reinforced concrete

International Nuclear Information System (INIS)

Choun, Young Sun; Seo, Jeong Moon

2001-03-01

For the ultimate behavior analysis of containment buildings under severe accident conditions, a clear understanding of tensile behaviors of plain and reinforced concrete is necessary. Nonlinear models for tensile behaviors of concrete are also needed. This report describe following items: tensile behaviors of plain concrete, test results of reinforced concrete panels in uniaxial and biaxial tension, tension stiffening. The tensile behaviors of reinforced concrete are significantly influenced by the properties of concrete and reinforcing steel. Thus, for a more reliable evaluation of tensile behavior and ultimate pressure capacity of a reinforced or prestressed concrete containment building, an advanced concrete model which can be considered rebar-concrete interaction effects should be developed. In additions, a crack behavior analysis method and tension stiffening models, which are based on fracture mechanics, should be developed. The model should be based on the various test data from specimens considering material and sectional properties of the containment building

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.

Mechanical Behaviour of Sisal Fibre Reinforced Cement Composites

OpenAIRE

M. Aruna

2014-01-01

Emphasis on the advancement of new materials and technology has been there for the past few decades. The global development towards using cheap and durable materials from renewable resources contributes to sustainable development. An experimental investigation of mechanical behaviour of sisal fibre-reinforced concrete is reported for making a suitable building material in terms of reinforcement. Fibre reinforced Composite is one such material, which has reformed the concept of high strength. ...

Superconducting properties and uniaxial strain characteristics of Nb3Sn fiber-reinforced superconductors with tantalum reinforcement fibers

International Nuclear Information System (INIS)

Arai, Kazuaki; Umeda, Masaichi; Agatsuma, Koh; Tateishi, Hiroshi

1998-01-01

We have been developing fiber-reinforced superconductors (FRS) for high-field and large-scale magnets. Tungsten fibers have been selected as the reinforcement fiber for FRS so far because tungsten has the highest elastic modulus of approximately 400 GPa which can minimize the strain from electromagnetic force. The preparation process of FRS consists of sputtering deposition and heat treatment because it may be difficult to apply drawing methods to materials of high-elastic modulus such as tungsten. Tantalum has high elastic modulus of 178 GPa and its thermal expansion coefficient that is closer to that of Nb 3 Sn than tungsten's, which means prestrain in Nb 3 Sn in FRS is reduced by adopting tantalum fibers. Tantalum has been used as barriers between bronze and copper in conventional Nb 3 Sn superconductors which are usually prepared with drawing process despite of the tantalum's high elastic modulus. That implies drawing process may be applied to prepare FRS with tantalum reinforcement fibers. In this paper, FRS using tantalum fibers prepared with sputtering process are described with making comparison with FRS of tungsten to clarify the basic properties of FRS using tantalum fibers. Depth profiles in Nb 3 Sn layer in FRS were measured to examine reaction between superconducting layers and reinforcement fibers. Superconducting properties including strain and stress characteristics were shown. Those data will contribute to design of FRS using tantalum reinforcement fibers with adopts the drawing processes. (author)

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

Structural performance evaluation on aging underground reinforced concrete structures. Part 6. An estimation method of threshold value in performance verification taking reinforcing steel corrosion

International Nuclear Information System (INIS)

Matsuo, Toyofumi; Matsumura, Takuro; Miyagawa, Yoshinori

2009-01-01

This paper discusses applicability of material degradation model due to reinforcing steel corrosion for RC box-culverts with corroded reinforcement and an estimation method for threshold value in performance verification reflecting reinforcing steel corrosion. First, in FEM analyses, loss of reinforcement section area and initial tension strain arising from reinforcing steel corrosion, and deteriorated bond characteristics between reinforcement and concrete were considered. The full-scale loading tests using corroded RC box-culverts were numerically analyzed. As a result, the analyzed crack patterns and load-strain relationships were in close agreement with the experimental results within the maximum corrosion ratio 15% of primary reinforcement. Then, we showed that this modeling could estimate the load carrying capacity of corroded RC box-culverts. Second, a parametric study was carried out for corroded RC box culverts with various sizes, reinforcement ratios and levels of steel corrosion, etc. Furthermore, as an application of analytical results and various experimental investigations, we suggested allowable degradation ratios for a modification of the threshold value, which corresponds to the chloride induced deterioration progress that is widely accepted in maintenance practice for civil engineering reinforced concrete structures. Finally, based on these findings, we developed two estimation methods for threshold value in performance verification: 1) a structural analysis method using nonlinear FEM included modeling of material degradation, 2) a practical method using a threshold value, which is determined by structural analyses of RC box-culverts in sound condition, is multiplied by the allowable degradation ratio. (author)

Corrosion of reinforcement induced by environment containing ...

Indian Academy of Sciences (India)

Unknown

carbonation and chlorides causing corrosion of steel reinforcement. ... interesting and important when the evaluation of the service life of the ... preferably in the areas of industrial and transport activities. ... For controlling the embedded corrosion sensors, elec- .... danger of corrosion of reinforcement seems to be more.

How edge-reinforced random walk arises naturally

NARCIS (Netherlands)

Rolles, S.W.W.

2003-01-01

We give a characterization of a modified edge-reinforced random walk in terms of certain partially exchangeable sequences. In particular, we obtain a characterization of an edge-reinforced random walk (introduced by Coppersmith and Diaconis) on a 2-edge-connected graph. Modifying the notion of

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

Directory of Open Access Journals (Sweden)

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.

Behavioral sensitivity to changing reinforcement contingencies in attention-deficit hyperactivity disorder.

Science.gov (United States)

Alsop, Brent; Furukawa, Emi; Sowerby, Paula; Jensen, Stephanie; Moffat, Cara; Tripp, Gail

2016-08-01

Altered sensitivity to positive reinforcement has been hypothesized to contribute to the symptoms of attention-deficit hyperactivity disorder (ADHD). In this study, we evaluated the ability of children with and without ADHD to adapt their behavior to changing reinforcer availability. Of one hundred sixty-seven children, 97 diagnosed with ADHD completed a signal-detection task in which correct discriminations between two stimuli were associated with different frequencies of reinforcement. The response alternative associated with the higher rate of reinforcement switched twice during the task without warning. For a subset of participants, this was followed by trials for which no reinforcement was delivered, irrespective of performance. Children in both groups developed an initial bias toward the more frequently reinforced response alternative. When the response alternative associated with the higher rate of reinforcement switched, the children's response allocation (bias) followed suit, but this effect was significantly smaller for children with ADHD. When reinforcement was discontinued, only children in the control group modified their response pattern. Children with ADHD adjust their behavioral responses to changing reinforcer availability less than typically developing children, when reinforcement is intermittent and the association between an action and its consequences is uncertain. This may explain the difficulty children with ADHD have adapting their behavior to new situations, with different reinforcement contingencies, in daily life. © 2016 Association for Child and Adolescent Mental Health.

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. 

Factors that influence the reinforcing value of foods and beverages.

Science.gov (United States)

Temple, Jennifer L

2014-09-01

Behavioral economic principles state that as the cost of a product increases, purchasing or consumption of that product will decrease. To understand the impact of behavioral economics on ingestive behavior, our laboratory utilizes an operant behavior paradigm to measure how much work an individual will engage in to get access to foods and beverages. This task provides an objective measure of the reinforcing value. We have shown that consumption of the same high fat snack food every day for two weeks reduces its reinforcing value in lean individuals, but increases its reinforcing value in a subset of obese individuals. This increase in the reinforcing value of food predicts future weight gain. Similarly, we have shown that repeated intake of caffeinated soda increases its reinforcing value in boys, but not in girls. This increase in reinforcing value is not related to usual caffeine consumption, but may be associated with positive, subjective effects of caffeine that are more likely to be reported by boys than by girls. Because food and beverage reinforcement relates to real-world consumption, it is important to determine factors that increase or decrease the reinforcing value and determine the consequences of these responses. We are especially interested in determining ways to shift the behavioral economic curve in order to develop novel strategies to decrease the reinforcing value of less healthy snack foods and beverages, such as soda, potato chips and candy and to increase the reinforcing value of healthier foods and beverages, such as water, fruits, and vegetables. Copyright © 2014 Elsevier Inc. All rights reserved.

Strain Capacity of Reinforced Concrete Members Subjected to Uniaxial Tension

DEFF Research Database (Denmark)

Hagsten, Lars German; Rasmussen, Annette Beedholm; Fisker, Jakob

2017-01-01

The aim of this paper is to set up a method to determine the strain capacity of tension bars of reinforced concrete (RC) subjected to pure tension. Due to the interaction between reinforcement and concrete and due to the presence of cracks, the stresses in both reinforcement and concrete...... are varying along the length of the tension bar. The strain capacity of the tension bar is seen as the average strain in the reinforcement at the load level corresponding to the ultimate stress capacity of the reinforcement at the cracks. The result of the approach is in overall good agreement when comparing...

Nutrigenómica, obesidad y salud pública.

Directory of Open Access Journals (Sweden)

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”.

Reinforcement, Behavior Constraint, and the Overjustification Effect.

Science.gov (United States)

Williams, Bruce W.

1980-01-01

Four levels of the behavior constraint-reinforcement variable were manipulated: attractive reward, unattractive reward, request to perform, and a no-reward control. Only the unattractive reward and request groups showed the performance decrements that suggest the overjustification effect. It is concluded that reinforcement does not cause the…

Continuous jute fibre reinforced laminated paper composite

Indian Academy of Sciences (India)

Jute fibre; laminated paper composite; plastic bag pollution. Abstract. Plastic bags create a serious environmental problem. The proposed jute fibre reinforced laminated paper composite and reinforcement-fibre free paper laminate may help to combat the war against this pollutant to certain extent. The paper laminate ...

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

Directory of Open Access Journals (Sweden)

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

Directory of Open Access Journals (Sweden)

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.

Maintenance of reinforcement to address the chronic nature of drug addiction.

Science.gov (United States)

Silverman, Kenneth; DeFulio, Anthony; Sigurdsson, Sigurdur O

2012-11-01

Drug addiction can be a chronic problem. Abstinence reinforcement can initiate drug abstinence, but as with other treatments many patients relapse after the intervention ends. Abstinence reinforcement can be maintained to promote long-term drug abstinence, but practical means of implementing long-term abstinence reinforcement are needed. We reviewed 8 clinical trials conducted in Baltimore, MD from 1996 through 2010 that evaluated the therapeutic workplace as a vehicle for maintaining reinforcement for the treatment of drug addiction. The therapeutic workplace uses employment-based reinforcement in which employees must provide objective evidence of drug abstinence or medication adherence to work and earn wages. Employment-based reinforcement can initiate (3 of 4 studies) and maintain (2 studies) cocaine abstinence in methadone patients, although relapse can occur even after long-term exposure to abstinence reinforcement (1 study). Employment-based reinforcement can also promote abstinence from alcohol in homeless alcohol dependent adults (1 study), and maintain adherence to extended-release naltrexone in opioid dependent adults (2 studies). Treatments should seek to promote life-long effects in patients. Therapeutic reinforcement may need to be maintained indefinitely to prevent relapse. Workplaces could be effective vehicles for the maintenance of therapeutic reinforcement contingencies for drug abstinence and adherence to addiction medications. Copyright © 2012 Elsevier Inc. All rights reserved.

Constitutive equations for cracked reinforced concrete based on a refined model

International Nuclear Information System (INIS)

Geistefeldt, H.

1977-01-01

Nonlinear numerical methods to calculate structures of reinforced concrete or of prestressed concrete are mostly based on two idealizing assumptions: tension stiffness perpendicular to cracks is equal to the stiffness of reinforcement alone and shear modulus is taken as constant. In real reinforced concrete structures concrete contributes to the tension-stiffness perpendicular to cracks and thus to the global stiffness matrix because of bond action between concrete and reinforcement and shear transfer in cracks is depending on stresses acting in cracks. Only few authors are taking these aspects into account and only with rough semiempirical assumptions. In this paper a refined nonlinear three-dimensional mechanical model for reinforced concrete is presented which can include these effects, hitherto neglected, depending on the given state of stress. The model is composed of three model-elements: component u - uncracked reinforced concrete with perfect bond (stiffness equal to the sum of the stiffnesses of concrete and reinforcement), component r - reinforcement free in surrounding concrete (reinforcement and concrete are having equal normal strains in noncracked directions and equal shear strains), component c - crack-part (shear stiffnesses in cracks is equal to the sum of shear stiffnesses of the reinforcement mesh, interface shear transfer and dowel action in cracks). (Auth.)

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

Directory of Open Access Journals (Sweden)

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.

Reinforcement Toolbox, a Parametric Reinforcement Modelling Tool for Curved Surface Structures

NARCIS (Netherlands)

Lauppe, J.; Rolvink, A.; Coenders, J.L.

2013-01-01

This paper presents a computational strategy and parametric modelling toolbox which aim at enhancing the design- and production process of reinforcement in freeform curved surface structures. The computational strategy encompasses the necessary steps of raising an architectural curved surface model

Reinforcement Learning in Autism Spectrum Disorder

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Manuela Schuetze

2017-11-01

Full Text Available Early behavioral interventions are recognized as integral to standard care in autism spectrum disorder (ASD, and often focus on reinforcing desired behaviors (e.g., eye contact and reducing the presence of atypical behaviors (e.g., echoing others' phrases. However, efficacy of these programs is mixed. Reinforcement learning relies on neurocircuitry that has been reported to be atypical in ASD: prefrontal-sub-cortical circuits, amygdala, brainstem, and cerebellum. Thus, early behavioral interventions rely on neurocircuitry that may function atypically in at least a subset of individuals with ASD. Recent work has investigated physiological, behavioral, and neural responses to reinforcers to uncover differences in motivation and learning in ASD. We will synthesize this work to identify promising avenues for future research that ultimately can be used to enhance the efficacy of early intervention.

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...

Mechanical properties of thermoplastic composites reinforced with Entada Mannii fibre

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Oluwayomi BALOGUN

2017-06-01

Full Text Available The mechanical properties and fracture mechanisms of thermoplastic composites reinforced with Entada mannii fibres was investigated. Polypropylene reinforced with 1, 3, 5, and 7 wt% KOH treated and untreated Entada mannii fibres were processed using a compression moulding machine. The tensile properties, impact strength, and flexural properties of the composites were evaluated while the tensile fracture surface morphology was examined using scanning electron microscopy. The results show that reinforcing polypropylene with Entada mannii fibres resulted in improvement of the tensile strength and elastic modulus. This improvement is remarkable for 5 wt% KOH treated Entada mannii fibre reinforced composites by 28 % increase as compared with the unreinforced polypropylene. The composites reinforced with Entada mannii fibres also had impact strength values of 70 % higher than the unreinforced polypropylene. However, the polypropylene reinforced with 5 and 7wt% KOH treated fibres exhibited significantly higher flexural strength and Young’s modulus by 53% and 52% increase as compared with the unreinforced polypropylene. The fracture surface of the polypropylene composites reinforced with untreated Entada mannii fibres were characterized by fibre debonding, fibre pull-out and matrix yielding while less voids and fibre pull-outs are observed in the composites reinforced with KOH treated Entada mannii fibres. v

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.

The partial-reinforcement extinction effect and the contingent-sampling hypothesis.

Science.gov (United States)

Hochman, Guy; Erev, Ido

2013-12-01

The partial-reinforcement extinction effect (PREE) implies that learning under partial reinforcements is more robust than learning under full reinforcements. While the advantages of partial reinforcements have been well-documented in laboratory studies, field research has failed to support this prediction. In the present study, we aimed to clarify this pattern. Experiment 1 showed that partial reinforcements increase the tendency to select the promoted option during extinction; however, this effect is much smaller than the negative effect of partial reinforcements on the tendency to select the promoted option during the training phase. Experiment 2 demonstrated that the overall effect of partial reinforcements varies inversely with the attractiveness of the alternative to the promoted behavior: The overall effect is negative when the alternative is relatively attractive, and positive when the alternative is relatively unattractive. These results can be captured with a contingent-sampling model assuming that people select options that provided the best payoff in similar past experiences. The best fit was obtained under the assumption that similarity is defined by the sequence of the last four outcomes.

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

Analysis of FRP bars used as reinforcement in concrete structures

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Kinga Brózda

2016-09-01

Full Text Available In the design and construction of building and engineering structures, it is of utmost importance to provide their reliability and safety. The use of FRP (Fiber Reinforced Polymers bars as reinforcement of structural concrete elements could help reducing the typical defects of reinforced concrete and increase its strength parameters. In the paper the selected FRP bar characteristic properties are presented and advantages derived therefrom are specified. Furthermore, the most commonly used in construction types of FRP bars, depending on the raw material used during the production process are listed. In addition, the possibility of recycling of elements reinforced with FRP bars is presented and compared with traditional reinforced concrete (reinforced with steel bars. The production method of FRP bars (pultrusion is shown. Moreover, the advantages and disadvantages of using this method are discussed.

Study on the Permeability Characteristics of Polyurethane Soil Stabilizer Reinforced Sand

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Jin Liu

2017-01-01

Full Text Available A polymer material of polyurethane soil stabilizer (PSS is used to reinforce the sand. To understand the permeability characteristics of PSS reinforced sand, a series of reinforcement layer form test, single-hole permeability test, and porous permeability test of sand reinforced with PSS have been performed. Reinforcement mechanism is discussed with scanning electron microscope images. The results indicated that the permeability resistance of sand reinforced with polyurethane soil stabilizer is improved through the formation of reinforcement layer on the sand surface. The thickness and complete degree of the reinforcement layer increase with the increasing of curing time and PSS concentration. The water flow rate decreases with the increasing of curing time or PSS concentration. The permeability coefficient decreases with the increasing of curing time and PSS concentration and increases with the increasing of depth in specimen. PSS fills up the voids of sand and adsorbs on the surface of sand particle to reduce or block the flowing channels of water to improve the permeability resistance of sand. The results can be applied as the reference for chemical reinforcement sandy soil engineering, especially for surface protection of embankment, slope, and landfill.

Design of reinforced concrete members based on structural mechanics

International Nuclear Information System (INIS)

Diaz, B.E.; Schulz, M.

1984-01-01

Up to now the design of reinforced concrete linear members is performed with the help of an inconsistent design theory, which nevertherless is sufficiently safe and simple to be used in the practice. The purpose of this paper is to present a rational reinforced concrete design method which is not too dissimilar to the present design rules, but is capable of defining consistently internal stresses along a reinforced concrete section. The present status of the completed computer procedures allows the analysis of linear reinforced concrete members formed by laminar reinforced concrete plates presenting variable thickness. A practical approach is presented for which the concrete and steel section is constant along the member axis. In this case, the concept of the equivalent section is introduced, which allows a simple analysis of the stress pattern along the member section. (Author) [pt

Influence of facing vertical stiffness on reinforced soil wall design

OpenAIRE

Puig Damians, Ivan; Bathurst, Richard; Josa Garcia-Tornel, Alejandro; Lloret Morancho, Antonio

2013-01-01

Current design practices for reinforced soil walls typically ignore the influence of facing type and foundation compressibility on the magnitude and distribution of reinforcement loads in steel reinforced soil walls under operational conditions. In this paper, the effect of the facing vertical stiffness (due to elastomeric bearing pads placed in the horizontal joints between panels) on load capacity of steel reinforced soil walls is examined in a systematic manner using a numerical modelli...

Normal Strength Steel Fiber Reinforced Concrete Subjected to Explosive Loading

OpenAIRE

Mohammed Alias Yusof; Norazman Norazman; Ariffin Ariffin; Fauzi Mohd Zain; Risby Risby; CP Ng

2011-01-01

This paper presents the results of an experimental investigation on the behavior of plain reinforced concrete and Normal strength steel fiber reinforced concrete panels (SFRC) subjected to explosive loading. The experiment were performed by the Blast Research Unit Faculty of Engineering, University Pertahanan Nasional Malaysia A total of 8 reinforced concrete panels of 600mm x 600mm x 100mm were tested. The steel fiber reinforced concrete panels incorporated three different volume fraction, 0...

Flexural strengthening of Reinforced Concrete (RC) Beams Retrofitted with Corrugated Glass Fiber Reinforced Polymer (GFRP) Laminates

Science.gov (United States)

Aravind, N.; Samanta, Amiya K.; Roy, Dilip Kr. Singha; Thanikal, Joseph V.

2015-01-01

Strengthening the structural members of old buildings using advanced materials is a contemporary research in the field of repairs and rehabilitation. Many researchers used plain Glass Fiber Reinforced Polymer (GFRP) sheets for strengthening Reinforced Concrete (RC) beams. In this research work, rectangular corrugated GFRP laminates were used for strengthening RC beams to achieve higher flexural strength and load carrying capacity. Type and dimensions of corrugated profile were selected based on preliminary study using ANSYS software. A total of twenty one beams were tested to study the load carrying capacity of control specimens and beams strengthened with plain sheets and corrugated laminates using epoxy resin. This paper presents the experimental and theoretical study on flexural strengthening of Reinforced Concrete (RC) beams using corrugated GFRP laminates and the results are compared. Mathematical models were developed based on the experimental data and then the models were validated.

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

Episodic reinforcement learning control approach for biped walking

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Katić Duško

2012-01-01

Full Text Available This paper presents a hybrid dynamic control approach to the realization of humanoid biped robotic walk, focusing on the policy gradient episodic reinforcement learning with fuzzy evaluative feedback. The proposed structure of controller involves two feedback loops: a conventional computed torque controller and an episodic reinforcement learning controller. The reinforcement learning part includes fuzzy information about Zero-Moment- Point errors. Simulation tests using a medium-size 36-DOF humanoid robot MEXONE were performed to demonstrate the effectiveness of our method.

Experience with dynamic reinforcement rates decreases resistance to extinction.

Science.gov (United States)

Craig, Andrew R; Shahan, Timothy A

2016-03-01

The ability of organisms to detect reinforcer-rate changes in choice preparations is positively related to two factors: the magnitude of the change in rate and the frequency with which rates change. Gallistel (2012) suggested similar rate-detection processes are responsible for decreases in responding during operant extinction. Although effects of magnitude of change in reinforcer rate on resistance to extinction are well known (e.g., the partial-reinforcement-extinction effect), effects of frequency of changes in rate prior to extinction are unknown. Thus, the present experiments examined whether frequency of changes in baseline reinforcer rates impacts resistance to extinction. Pigeons pecked keys for variable-interval food under conditions where reinforcer rates were stable and where they changed within and between sessions. Overall reinforcer rates between conditions were controlled. In Experiment 1, resistance to extinction was lower following exposure to dynamic reinforcement schedules than to static schedules. Experiment 2 showed that resistance to presession feeding, a disruptor that should not involve change-detection processes, was unaffected by baseline-schedule dynamics. These findings are consistent with the suggestion that change detection contributes to extinction. We discuss implications of change-detection processes for extinction of simple and discriminated operant behavior and relate these processes to the behavioral-momentum based approach to understanding extinction. © 2016 Society for the Experimental Analysis of Behavior.

Electrochemical extraction of chlorides from reinforced concrete: variables affecting treatment efficiency

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Climent, M. A.

2006-12-01

Full Text Available This paper reports the results of applying electrochemical chloride extraction (ECE to a series of chloride-contaminated concrete specimens. Experimental conditions were varied to study the efficiency of this technique under different circumstances. The survey covered the possible relationship between efficiency and the location of the sampling point, current density, type of concrete and treatment intermittence. Experiments were also conducted with different reinforcement configurations used in standard structural members such as columns and beams to ascertain the impact of rebar geometry.Este documento aporta los resultados de investigaciones realizadas en diferentes estudios en los que se aplicó la técnica de Extracción Electroquímica de Cloruros (EEC a diferentes estructuras de hormigón contaminado con cloruros. Se cambiaron las condiciones experimentales con el fin de estudiar la eficiencia de la misma en cada una de ellas. Se estudió la dependencia con la posición del punto de toma de las muestras, con la densidad de corriente aplicada, con el tipo de hormigón utilizado y con las paradas realizadas en etapas intermedias del tratamiento. Para ver la influencia de la disposición geométrica de las armaduras,se realizó una experiencia con tipos diferentes de disposiciones de las armaduras, correspondiente a componentes estructurales típicos como los pilares y las vigas.

Full Scale Reinforced Concrete Beam-Column Joints Strengthened with Steel Reinforced Polymer Systems

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Alessandro De Vita

2017-07-01

Full Text Available This paper presents the results of an experimental campaign performed at the Laboratory of Materials and Structural Testing of the University of Salerno (Italy in order to investigate the seismic performance of reinforced concrete (RC beam-column joints strengthened with steel reinforced polymer (SRP systems. With the aim to represent typical façade frames’ beam-column subassemblies found in existing RC buildings, specimens were provided with two short beam stubs orthogonal to the main beam and were designed with inadequate seismic details. Five members were strengthened by using two different SRP layouts while the remaining ones were used as benchmarks. Once damaged, two specimens were also repaired, retrofitted with SRP, and subjected to cyclic test again. The results of cyclic tests performed on SRP strengthened joints are examined through a comparison with the outcomes of the previous experimental program including companion specimens not provided with transverse beam stubs and strengthened by carbon fiber-reinforced polymer (CFRP systems. In particular, both qualitative and quantitative considerations about the influence of the confining effect provided by the secondary beams on the joint response, the suitability of all the adopted strengthening solutions (SRP/CFRP systems, the performances and the failure modes experienced in the several cases studied are provided.

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).

Investigating aluminum alloy reinforced by graphene nanoflakes

Energy Technology Data Exchange (ETDEWEB)

Yan, S.J., E-mail: shaojiuyan@126.com [Beijing Institute of Aeronautical Materials, Beijing 100095 (China); Dai, S.L.; Zhang, X.Y.; Yang, C.; Hong, Q.H.; Chen, J.Z. [Beijing Institute of Aeronautical Materials, Beijing 100095 (China); Lin, Z.M. [Aviation Industry Corporation of China, Beijing 100022 (China)

2014-08-26

As one of the most important engineering materials, aluminum alloys have been widely applied in many fields. However, the requirement of enhancing their mechanical properties without sacrificing the ductility is always a challenge in the development of aluminum alloys. Thanks to the excellent physical and mechanical properties, graphene nanoflakes (GNFs) have been applied as promising reinforcing elements in various engineering materials, including polymers and ceramics. However, the investigation of GNFs as reinforcement phase in metals or alloys, especially in aluminum alloys, is still very limited. In this study, the aluminum alloy reinforced by GNFs was successfully prepared via powder metallurgy approach. The GNFs were mixed with aluminum alloy powders through ball milling and followed by hot isostatic pressing. The green body was then hot extruded to obtain the final GNFs reinforced aluminum alloy nanocomposite. The scanning electron microscopy and transmission electron microscope analysis show that GNFs were well dispersed in the aluminum alloy matrix and no chemical reactions were observed at the interfaces between the GNFs and aluminum alloy matrix. The mechanical properties' testing results show that with increasing filling content of GNFs, both tensile and yield strengths were remarkably increased without losing the ductility performance. These results not only provided a pathway to achieve the goal of preparing high strength aluminum alloys with excellent ductilitybut they also shed light on the development of other metal alloys reinforced by GNFs.

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.

Continuous carbon nanotube reinforced composites.

Science.gov (United States)

Ci, L; Suhr, J; Pushparaj, V; Zhang, X; Ajayan, P M

2008-09-01

Carbon nanotubes are considered short fibers, and polymer composites with nanotube fillers are always analogues of random, short fiber composites. The real structural carbon fiber composites, on the other hand, always contain carbon fiber reinforcements where fibers run continuously through the composite matrix. With the recent optimization in aligned nanotube growth, samples of nanotubes in macroscopic lengths have become available, and this allows the creation of composites that are similar to the continuous fiber composites with individual nanotubes running continuously through the composite body. This allows the proper utilization of the extreme high modulus and strength predicted for nanotubes in structural composites. Here, we fabricate such continuous nanotube polymer composites with continuous nanotube reinforcements and report that under compressive loadings, the nanotube composites can generate more than an order of magnitude improvement in the longitudinal modulus (up to 3,300%) as well as damping capability (up to 2,100%). It is also observed that composites with a random distribution of nanotubes of same length and similar filler fraction provide three times less effective reinforcement in composites.

Reinforcement learning in computer vision

Science.gov (United States)

Bernstein, A. V.; Burnaev, E. V.

2018-04-01

Nowadays, machine learning has become one of the basic technologies used in solving various computer vision tasks such as feature detection, image segmentation, object recognition and tracking. In many applications, various complex systems such as robots are equipped with visual sensors from which they learn state of surrounding environment by solving corresponding computer vision tasks. Solutions of these tasks are used for making decisions about possible future actions. It is not surprising that when solving computer vision tasks we should take into account special aspects of their subsequent application in model-based predictive control. Reinforcement learning is one of modern machine learning technologies in which learning is carried out through interaction with the environment. In recent years, Reinforcement learning has been used both for solving such applied tasks as processing and analysis of visual information, and for solving specific computer vision problems such as filtering, extracting image features, localizing objects in scenes, and many others. The paper describes shortly the Reinforcement learning technology and its use for solving computer vision problems.

Aprendiendo química con golosinas

Directory of Open Access Journals (Sweden)

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.

Teaching Self-Control with Qualitatively Different Reinforcers

Science.gov (United States)

Passage, Michael; Tincani, Matt; Hantula, Donald A.

2012-01-01

This study examined the effectiveness of using qualitatively different reinforcers to teach self-control to an adolescent boy who had been diagnosed with an intellectual disability. First, he was instructed to engage in an activity without programmed reinforcement. Next, he was instructed to engage in the activity under a two-choice fixed-duration…

Turbomachine blade reinforcement

Science.gov (United States)

Garcia Crespo, Andres Jose

2016-09-06

Embodiments of the present disclosure include a system having a turbomachine blade segment including a blade and a mounting segment coupled to the blade, wherein the mounting segment has a plurality of reinforcement pins laterally extending at least partially through a neck of the mounting segment.

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

South Oregon Coast Reinforcement.

Energy Technology Data Exchange (ETDEWEB)

United States. Bonneville Power Administration.

1998-05-01

The Bonneville Power Administration is proposing to build a transmission line to reinforce electrical service to the southern coast of Oregon. This FYI outlines the proposal, tells how one can learn more, and how one can share ideas and opinions. The project will reinforce Oregon`s south coast area and provide the necessary transmission for Nucor Corporation to build a new steel mill in the Coos Bay/North Bend area. The proposed plant, which would use mostly recycled scrap metal, would produce rolled steel products. The plant would require a large amount of electrical power to run the furnace used in its steel-making process. In addition to the potential steel mill, electrical loads in the south Oregon coast area are expected to continue to grow.

Nanostructured composite reinforced material

Science.gov (United States)

Seals, Roland D [Oak Ridge, TN; Ripley, Edward B [Knoxville, TN; Ludtka, Gerard M [Oak Ridge, TN

2012-07-31

A family of materials wherein nanostructures and/or nanotubes are incorporated into a multi-component material arrangement, such as a metallic or ceramic alloy or composite/aggregate, producing a new material or metallic/ceramic alloy. The new material has significantly increased strength, up to several thousands of times normal and perhaps substantially more, as well as significantly decreased weight. The new materials may be manufactured into a component where the nanostructure or nanostructure reinforcement is incorporated into the bulk and/or matrix material, or as a coating where the nanostructure or nanostructure reinforcement is incorporated into the coating or surface of a "normal" substrate material. The nanostructures are incorporated into the material structure either randomly or aligned, within grains, or along or across grain boundaries.

Value learning through reinforcement : The basics of dopamine and reinforcement learning

NARCIS (Netherlands)

Daw, N.D.; Tobler, P.N.; Glimcher, P.W.; Fehr, E.

2013-01-01

This chapter provides an overview of reinforcement learning and temporal difference learning and relates these topics to the firing properties of midbrain dopamine neurons. First, we review the RescorlaWagner learning rule and basic learning phenomena, such as blocking, which the rule explains. Then

EL CONGRESO DE KARLSRUHE: PASO DEFINITIVO HACIA LA QUÍMICA MODERNA

Directory of Open Access Journals (Sweden)

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

Directory of Open Access Journals (Sweden)

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.

Cohesive fracture model for functionally graded fiber reinforced concrete

International Nuclear Information System (INIS)

Park, Kyoungsoo; Paulino, Glaucio H.; Roesler, Jeffery

2010-01-01

A simple, effective, and practical constitutive model for cohesive fracture of fiber reinforced concrete is proposed by differentiating the aggregate bridging zone and the fiber bridging zone. The aggregate bridging zone is related to the total fracture energy of plain concrete, while the fiber bridging zone is associated with the difference between the total fracture energy of fiber reinforced concrete and the total fracture energy of plain concrete. The cohesive fracture model is defined by experimental fracture parameters, which are obtained through three-point bending and split tensile tests. As expected, the model describes fracture behavior of plain concrete beams. In addition, it predicts the fracture behavior of either fiber reinforced concrete beams or a combination of plain and fiber reinforced concrete functionally layered in a single beam specimen. The validated model is also applied to investigate continuously, functionally graded fiber reinforced concrete composites.

Development of a relationship between external measurements and reinforcement stress

Science.gov (United States)

Brault, Andre; Hoult, Neil A.; Lees, Janet M.

2015-03-01

As many countries around the world face an aging infrastructure crisis, there is an increasing need to develop more accurate monitoring and assessment techniques for reinforced concrete structures. One of the challenges associated with assessing existing infrastructure is correlating externally measured parameters such as crack widths and surface strains with reinforcement stresses as this is dependent on a number of variables. The current research investigates how the use of distributed fiber optic sensors to measure reinforcement strain can be correlated with digital image correlation measurements of crack widths to relate external crack width measurements to reinforcement stresses. An initial set of experiments was undertaken involving a series of small-scale beam specimens tested in three-point bending with variable reinforcement properties. Relationships between crack widths and internal reinforcement strains were observed including that both the diameter and number of bars affected the measured maximum strain and crack width. A model that uses measured crack width to estimate reinforcement strain was presented and compared to the experimental results. The model was found to provide accurate estimates of load carrying capacity for a given crack width, however, the model was potentially less accurate when crack widths were used to estimate the experimental reinforcement strains. The need for more experimental data to validate the conclusions of this research was also highlighted.

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

Directory of Open Access Journals (Sweden)

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.

Human-level control through deep reinforcement learning

Science.gov (United States)

Mnih, Volodymyr; Kavukcuoglu, Koray; Silver, David; Rusu, Andrei A.; Veness, Joel; Bellemare, Marc G.; Graves, Alex; Riedmiller, Martin; Fidjeland, Andreas K.; Ostrovski, Georg; Petersen, Stig; Beattie, Charles; Sadik, Amir; Antonoglou, Ioannis; King, Helen; Kumaran, Dharshan; Wierstra, Daan; Legg, Shane; Hassabis, Demis

2015-02-01

The theory of reinforcement learning provides a normative account, deeply rooted in psychological and neuroscientific perspectives on animal behaviour, of how agents may optimize their control of an environment. To use reinforcement learning successfully in situations approaching real-world complexity, however, agents are confronted with a difficult task: they must derive efficient representations of the environment from high-dimensional sensory inputs, and use these to generalize past experience to new situations. Remarkably, humans and other animals seem to solve this problem through a harmonious combination of reinforcement learning and hierarchical sensory processing systems, the former evidenced by a wealth of neural data revealing notable parallels between the phasic signals emitted by dopaminergic neurons and temporal difference reinforcement learning algorithms. While reinforcement learning agents have achieved some successes in a variety of domains, their applicability has previously been limited to domains in which useful features can be handcrafted, or to domains with fully observed, low-dimensional state spaces. Here we use recent advances in training deep neural networks to develop a novel artificial agent, termed a deep Q-network, that can learn successful policies directly from high-dimensional sensory inputs using end-to-end reinforcement learning. We tested this agent on the challenging domain of classic Atari 2600 games. We demonstrate that the deep Q-network agent, receiving only the pixels and the game score as inputs, was able to surpass the performance of all previous algorithms and achieve a level comparable to that of a professional human games tester across a set of 49 games, using the same algorithm, network architecture and hyperparameters. This work bridges the divide between high-dimensional sensory inputs and actions, resulting in the first artificial agent that is capable of learning to excel at a diverse array of challenging tasks.

Human-level control through deep reinforcement learning.

Science.gov (United States)

Mnih, Volodymyr; Kavukcuoglu, Koray; Silver, David; Rusu, Andrei A; Veness, Joel; Bellemare, Marc G; Graves, Alex; Riedmiller, Martin; Fidjeland, Andreas K; Ostrovski, Georg; Petersen, Stig; Beattie, Charles; Sadik, Amir; Antonoglou, Ioannis; King, Helen; Kumaran, Dharshan; Wierstra, Daan; Legg, Shane; Hassabis, Demis

2015-02-26

The theory of reinforcement learning provides a normative account, deeply rooted in psychological and neuroscientific perspectives on animal behaviour, of how agents may optimize their control of an environment. To use reinforcement learning successfully in situations approaching real-world complexity, however, agents are confronted with a difficult task: they must derive efficient representations of the environment from high-dimensional sensory inputs, and use these to generalize past experience to new situations. Remarkably, humans and other animals seem to solve this problem through a harmonious combination of reinforcement learning and hierarchical sensory processing systems, the former evidenced by a wealth of neural data revealing notable parallels between the phasic signals emitted by dopaminergic neurons and temporal difference reinforcement learning algorithms. While reinforcement learning agents have achieved some successes in a variety of domains, their applicability has previously been limited to domains in which useful features can be handcrafted, or to domains with fully observed, low-dimensional state spaces. Here we use recent advances in training deep neural networks to develop a novel artificial agent, termed a deep Q-network, that can learn successful policies directly from high-dimensional sensory inputs using end-to-end reinforcement learning. We tested this agent on the challenging domain of classic Atari 2600 games. We demonstrate that the deep Q-network agent, receiving only the pixels and the game score as inputs, was able to surpass the performance of all previous algorithms and achieve a level comparable to that of a professional human games tester across a set of 49 games, using the same algorithm, network architecture and hyperparameters. This work bridges the divide between high-dimensional sensory inputs and actions, resulting in the first artificial agent that is capable of learning to excel at a diverse array of challenging tasks.

Liberalização financeira, performance econômica e estabilidade macroeconômica no Brasil: uma avaliação do período 1994-2007

Directory of Open Access Journals (Sweden)

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

Directory of Open Access Journals (Sweden)

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

Thermomechanical analyses of phenolic foam reinforced with glass fiber mat

International Nuclear Information System (INIS)

Zhou, Jintang; Yao, Zhengjun; Chen, Yongxin; Wei, Dongbo; Wu, Yibing

2013-01-01

Highlights: • Over 10% glass fiber was used to reinforce phenolic foam in the shape of glass fiber mat. • Nucleating agents were used together with glass fiber mat and improved tensile strength of phenolic foam by 215.6%. • Nucleating agents lead to a smaller bubble size of phenolic foam. • The glass transition temperature of phenolic foam remained unchanged during the reinforcement. - Abstract: In this paper, thermomechanical analysis (TMA) and dynamic mechanical analysis were employed to study the properties of phenolic foam reinforced with glass fiber mat. Unreinforced phenolic foam was taken as the control sample. Mechanical tests and scanning electron microscopy were performed to confirm the results of TMA. The results show that glass fiber mat reinforcement improves the mechanical performance of phenolic foam, and nucleating agents improve it further. Phenolic foam reinforced with glass fiber mat has a smaller thermal expansion coefficient compared with unreinforced foam. The storage modulus of the reinforced phenolic foam is also higher than that in unreinforced foam, whereas the loss modulus of the former is lower than that of the latter. The glass transition temperature of the phenolic foam matrix remains unchanged during the reinforcement

Graphene-Reinforced Metal and Polymer Matrix Composites

Science.gov (United States)

Kasar, Ashish K.; Xiong, Guoping; Menezes, Pradeep L.

2018-06-01

Composites have tremendous applicability due to their excellent capabilities. The performance of composites mainly depends on the reinforcing material applied. Graphene is successful as an efficient reinforcing material due to its versatile as well as superior properties. Even at very low content, graphene can dramatically improve the properties of polymer and metal matrix composites. This article reviews the fabrication followed by mechanical and tribological properties of metal and polymer matrix composites filled with different kinds of graphene, including single-layer, multilayer, and functionalized graphene. Results reported to date in literature indicate that functionalized graphene or graphene oxide-polymer composites are promising materials offering significantly improved strength and frictional properties. A similar trend of improved properties has been observed in case of graphene-metal matrix composites. However, achieving higher graphene loading with uniform dispersion in metal matrix composites remains a challenge. Although graphene-reinforced composites face some challenges, such as understanding the graphene-matrix interaction or fabrication techniques, graphene-reinforced polymer and metal matrix composites have great potential for application in various fields due to their outstanding properties.

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.

Is cascade reinforcement likely when sympatric and allopatric populations exchange migrants?

Science.gov (United States)

Yukilevich, Roman; Aoki, Fumio

2016-04-01

When partially reproductively isolated species come back into secondary contact, these taxa may diverge in mating preferences and sexual cues to avoid maladaptive hybridization, a process known as reinforcement. This phenomenon often leads to reproductive character displacement (RCD) between sympatric and allopatric populations of reinforcing species that differ in their exposure to hybridization. Recent discussions have reinvigorated the idea that RCD may give rise to additional speciation between conspecific sympatric and allopatric populations, dubbing the concept "cascade reinforcement." Despite some empirical studies supporting cascade reinforcement, we still know very little about the conditions for its evolution. In the present article, we address this question by developing an individual-based population genetic model that explicitly simulates cascade reinforcement when one of the hybridizing species is split into sympatric and allopatric populations. Our results show that when sympatric and allopatric populations reside in the same environment and only differ in their exposure to maladaptive hybridization, migration between them generally inhibits the evolution of cascade by spreading the reinforcement alleles from sympatry into allopatry and erasing RCD. Under these conditions, cascade reinforcement only evolved when migration rate between sympatric and allopatric populations was very low. This indicates that stabilizing sexual selection in allopatry is generally ineffective in preventing the spread of reinforcement alleles. Only when sympatric and allopatric populations experienced divergent ecological selection did cascade reinforcement evolve in the presence of substantial migration. These predictions clarify the conditions for cascade reinforcement and facilitate our understanding of existing cases in nature.

Repair of reinforced concrete beams using carbon fiber reinforced polymer

Directory of Open Access Journals (Sweden)

Karzad Abdul Saboor

2017-01-01

Full Text Available This research paper is part of an ongoing research on the behaviour of Reinforced Concrete (RC beams retrofitted with Externally Bonded Carbon Fiber Reinforced Polymer (EB-CFRP. A total of 5 large-scale rectangular beams, previously damaged due to shear loading, were repaired and strengthened with EB-CFRP and tested in this study. The major cracks of the damaged beams were injected with epoxy and the beams were wrapped with 2 layers of EB-CFRP discrete strips with 100mm width and 150mm center to center spacing. The beams were instrumented and tested to failure under three points loading in simply supported configuration. The measured test parameters were the beams deflection, maximum load, and the strain in the FRP strips. The failure mode was also observed. The results showed that applying EB-FRP strips increased the shear strength significantly relative to the original shear capacity of the beam. The results demonstrate that the application of EB-FRP strips used in this study is an effective repair method that can be used to repair and strengthen damaged beams.

Hypocretin / orexin involvement in reward and reinforcement

Science.gov (United States)

España, Rodrigo A.

2015-01-01

Since the discovery of the hypocretins/orexins, a series of observations have indicated that these peptides influence a variety of physiological processes including feeding, sleep/wake function, memory, and stress. More recently, the hypocretins have been implicated in reinforcement and reward-related processes via actions on the mesolimbic dopamine system. Although investigation into the relationship between the hypocretins and reinforcement/reward remains in relatively early stages, accumulating evidence suggests that continued research into this area may offer new insights into the addiction process and provide the foundation to generate novel pharmacotherapies for drug abuse. The current chapter will focus on contemporary perspectives of hypocretin regulation of cocaine reward and reinforcement via actions on the mesolimbic dopamine system. PMID:22640614

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...

Continuous Natural Fiber Reinforced Thermoplastic Composites by Fiber Surface Modification

Directory of Open Access Journals (Sweden)

Patcharat Wongsriraksa

2013-01-01

Full Text Available Continuous natural fiber reinforced thermoplastic materials are expected to replace inorganic fiber reinforced thermosetting materials. However, in the process of fabricating the composite, it is difficult to impregnate the thermoplastic resin into reinforcement fiber because of the high melt viscosity. Therefore, intermediate material, which allows high impregnation during molding, has been investigated for fabricating continuous fiber reinforced thermoplastic composite by aligning resin fiber alongside reinforcing fiber with braiding technique. This intermediate material has been called “microbraid yarn (MBY.” Moreover, it is well known that the interfacial properties between natural fiber and resin are low; therefore, surface treatment on continuous natural fiber was performed by using polyurethane (PU and flexible epoxy (FLEX to improve the interfacial properties. The effect of surface treatment on the mechanical properties of continuous natural fiber reinforced thermoplastic composites was examined. From these results, it was suggested that surface treatment by PU with low content could produce composites with better mechanical properties.

Manipulating parameters of reinforcement to reduce problem behavior without extinction.

Science.gov (United States)

Kunnavatana, S Shanun; Bloom, Sarah E; Samaha, Andrew L; Slocum, Timothy A; Clay, Casey J

2018-04-01

Differential reinforcement of alternative behavior (DRA) most often includes extinction as a treatment component. However, extinction is not always feasible and it can be counter-therapeutic if implemented without optimal treatment integrity. Researchers have successfully implemented DRA without extinction by manipulating various parameters of reinforcement such that alternative behavior is favored. We extended previous research by assessing three participants' sensitivities to quality, magnitude, and immediacy using arbitrary responses and reinforcers that maintain problem behavior. The results were used to implement an intervention for problem behavior using DRA without extinction. Our findings indicate that arbitrary responses can be used to identify individual and relative sensitivity to parameters of reinforcement for reinforcers that maintain problem behavior. Treatment was effective for all participants when we manipulated parameters of reinforcement to which they were most sensitive, and, for two participants, the treatment was less effective when we manipulated parameters to which they were least sensitive. © 2018 Society for the Experimental Analysis of Behavior.

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.

Design Methods for Fibre Reinforced Concrete

DEFF Research Database (Denmark)

Stang, Henrik

1996-01-01

The present paper describes the outline of a research project on Fibre Reinforced Concrete (FRC) currently being carried out in Denmark under the supervision of Danish Council of Technology, Danish Technical Research Council and Danish Natural Science Research Counsil.......The present paper describes the outline of a research project on Fibre Reinforced Concrete (FRC) currently being carried out in Denmark under the supervision of Danish Council of Technology, Danish Technical Research Council and Danish Natural Science Research Counsil....

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.

Sisal organosolv pulp as reinforcement for cement based composites

Directory of Open Access Journals (Sweden)

Ana Paula Joaquim

2009-09-01

Full Text Available The present work describes non-conventional sisal (Agave sisalana chemical (organosolv pulp from residues of cordage as reinforcement to cement based materials. Sisal organosolv pulp was produced in a 1:1 ethanol/water mixture and post chemically and physically characterized in order to compare its properties with sisal kraft pulp. Cement based composites reinforced with organosolv or kraft pulps and combined with polypropylene (PP fibres were produced by the slurry de-watering and pressing method as a crude simulation of the Hatschek process. Composites were evaluated at 28 days of age, after exposition to accelerated carbonation and after 100 soak/dry cycles. Composites containing organosolv pulp presented lower mechanical strength, water absorption and apparent porosity than composites reinforced with kraft pulp. The best mechanical performance after ageing was also achieved by samples reinforced with kraft pulp. The addition of PP fibres favoured the maintenance of toughness after ageing. Accelerated carbonation promoted the densification of the composites reinforced with sisal organosolv + PP fibres.

Mechanical properties of aluminium matrix composites reinforced with intermetallics

International Nuclear Information System (INIS)

Torres, B.; Garcia-Escorial, A.; Ibanez, J.; Lieblich, M.

2001-01-01

In this work 2124 aluminium matrix composites reinforced with Ni 3 Al, NiAl, MoSi 2 and Cr 3 Si intermetallic powder particles have been investigated. For comparison purposes, un reinforced 2124 and reinforced with SiC have also been studied. In all cases, the same powder metallurgy route was used, i. e. the 2124 alloy was obtained by rapid solidification and the intermetallic particles by self-propagating high-temperature synthesis (SHS). The matrix and the intermetallics were mechanically blended, cold compacted and finally hot extruded. Tensile tests were carried out in T1 and T4 treatments. Results indicate that mechanical properties depend strongly on the tendency to form new phases at the matrix-intermetallic interface during processing and/or further thermal treatments. The materials which present better properties are those that present less reaction between matrix and intermetallic reinforcement, i. e. MoSi 2 and SiC reinforced composites. (Author) 9 refs

Reinforcing method for reinforced concrete structures by using carbon fibers; Tanso sen`i ni yoru tekkin concrete kozobutsu no hokyo koho

Energy Technology Data Exchange (ETDEWEB)

Tanaka, T.; Taniki, K. [Mitsubishi Kasei Corp., Tokyo (Japan); Kojima, N.; Kimura, K.; Katsumata, H. [Obayashi Corp., Osaka (Japan)

1994-08-15

This paper describes the development of a reinforcing method for reinforced concrete (hereinafter RC) structures by using carbon fibers (hereinafter CF). This developed method attaches a light-weight CFUD prepreg material for reinforcement by laterally winding CF strand impregnated with epoxy resin, which is hardened under normal temperature. This method is economical because no skills and special tools are required. An RC pillar with circular cross section and a hollow RC test body assuming a chimney were used as models. The paper details the experiment. This method has been used in several ten existing RC stacks with effective reinforcing result. Resistance strengths of CF strands and UD prepregs were verified in an accelerated exposure test performed according to JIS A 1415, standard for plastic building materials. The effects of the anti-seismic reinforcement have resulted in improvement in shear resistance force in RC pillars by means of CF winding method, improvement in bending stress in RC structures as a result of CF attaching method, and effectiveness in repair of existing RC stacks. Sufficient exposure resistance has also been proved. A bending test by means of two-point concentrated loading has been performed as a weighted test. 4 figs.

Evolución hacia la cerámica fotovoltaica

Directory of Open Access Journals (Sweden)

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

Tribological performance of polymer composites used in electrical ...

Indian Academy of Sciences (India)

engineering applications. ZAFER DEMIR. Anadolu University, Eskisehir, Turkey. MS received 28 December 2011; revised 13 March 2012. Abstract. Sliding wear performance of 20% mica-filled polyamide 6 (PA6 + 20% mica) and 20% short glass fibre- reinforced polysulphone (PSU + 20 GFR) polymer composites used in ...

Investigation on reinforced concrete slabs subjeted to impact loading

International Nuclear Information System (INIS)

Freiman, M.; Krutzik, N.J.; Tropp, R.; Zorn, N.F.

1984-01-01

A comparison of experimental and computational results for tests of reinforced concrete slabs subjected to soft missile impact is presented. Numerical simulation techniques were employed to predict the target response. The objective of the calculations was to validate the material model for reinforced concrete implemented in a finite difference code. The computational results regarding displacements or strains in the reinforcement conform satisfactorily with the experimental values. (Author) [pt

Investigation of digital light processing using fibre-reinforced polymers

DEFF Research Database (Denmark)

Hofstätter, Thomas; Pedersen, David Bue; Nielsen, Jakob Skov

2016-01-01

Literature research shows multiple applications of fibre-reinforced polymers (FRP) respectively in fused deposition modelling and gypsum printing influencing the quality of the products in terms of stress and strain resistance as well as flexibility. So far, applications of fibre-reinforced polym......Literature research shows multiple applications of fibre-reinforced polymers (FRP) respectively in fused deposition modelling and gypsum printing influencing the quality of the products in terms of stress and strain resistance as well as flexibility. So far, applications of fibre...... of miniaturized objects with relatively high surface quality compared to other additive manufacturing technologies. This paper aim to move fibre reinforced resin parts one step closer towards mechanically strong production-quality components....

Modeling reinforced concrete durability.

Science.gov (United States)

2014-06-01

This project developed a next-generation modeling approach for projecting the extent of : reinforced concrete corrosion-related damage, customized for new and existing Florida Department of : Transportation bridges and suitable for adapting to broade...

Dinámica fisicoquímica de las aguas de un sistema de planicies inundables tropicales

Directory of Open Access Journals (Sweden)

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.

Effect of reinforcer magnitude on performance maintained by progressive-ratio schedules.

Science.gov (United States)

Rickard, J F; Body, S; Zhang, Z; Bradshaw, C M; Szabadi, E

2009-01-01

This experiment examined the relationship between reinforcer magnitude and quantitative measures of performance on progressive-ratio schedules. Fifteen rats were trained under a progressive-ratio schedule in seven phases of the experiment in which the volume of a 0.6-M sucrose solution reinforcer was varied within the range 6-300 microl. Overall response rates in successive ratios conformed to a bitonic equation derived from Killeen's (1994) Mathematical Principles of Reinforcement. The "specific activation" parameter, a, which is presumed to reflect the incentive value of the reinforcer, was a monotonically increasing function of reinforcer volume; the "response time" parameter, delta, which defines the minimum response time, increased as a function of reinforcer volume; the "currency" parameter, beta, which is presumed to reflect the coupling of responses to the reinforcer, declined as a function of volume. Running response rate (response rate calculated after exclusion of the postreinforcement pause) decayed monotonically as a function of ratio size; the index of curvature of this function increased as a function of reinforcer volume. Postreinforcement pause increased as a function of ratio size. Estimates of a derived from overall response rates and postreinforcement pauses showed a modest positive correlation across conditions and between animals. Implications of the results for the quantification of reinforcer value and for the use of progressive-ratio schedules in behavioral neuroscience are discussed.

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

Directory of Open Access Journals (Sweden)

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.

Wrinkles in reinforced membranes

Science.gov (United States)

Takei, Atsushi; Brau, Fabian; Roman, Benoît; Bico, José.

2012-02-01

We study, through model experiments, the buckling under tension of an elastic membrane reinforced with a more rigid strip or a fiber. In these systems, the compression of the rigid layer is induced through Poisson contraction as the membrane is stretched perpendicularly to the strip. Although strips always lead to out-of-plane wrinkles, we observe a transition from out-of-plane to in plane wrinkles beyond a critical strain in the case of fibers embedded into the elastic membranes. The same transition is also found when the membrane is reinforced with a wall of the same material depending on the aspect ratio of the wall. We describe through scaling laws the evolution of the morphology of the wrinkles and the different transitions as a function of material properties and stretching strain.

Mechanical Behavior of Granular/Particulate Media Reinforced with Fibers

National Research Council Canada - National Science Library

Michalowski, Radoslw

1999-01-01

Fiber-reinforced ganular composites (for instance, fiber-reinforced sand) are considered as construction materials for such applications as subgrades of airfields and roads, aircraft parking facilities, etc...

Punishment Insensitivity and Impaired Reinforcement Learning in Preschoolers

Science.gov (United States)

Briggs-Gowan, Margaret J.; Nichols, Sara R.; Voss, Joel; Zobel, Elvira; Carter, Alice S.; McCarthy, Kimberly J.; Pine, Daniel S.; Blair, James; Wakschlag, Lauren S.

2014-01-01

Background: Youth and adults with psychopathic traits display disrupted reinforcement learning. Advances in measurement now enable examination of this association in preschoolers. The current study examines relations between reinforcement learning in preschoolers and parent ratings of reduced responsiveness to socialization, conceptualized as a…

Reinforcement learning in continuous state and action spaces

NARCIS (Netherlands)

H. P. van Hasselt (Hado); M.A. Wiering; M. van Otterlo

2012-01-01

textabstractMany traditional reinforcement-learning algorithms have been designed for problems with small finite state and action spaces. Learning in such discrete problems can been difficult, due to noise and delayed reinforcements. However, many real-world problems have continuous state or action

Ultimate load capacity assessment of reinforced concrete shell structures

International Nuclear Information System (INIS)

Gupta, Amita; Singh, R.K.; Kushwaha, H.S.; Mahajan, S.C.; Kakodkar, A.

1993-01-01

The objective of this study is to develop capability for prediction of ultimate load capacity of reinforced concrete shell structures. The present finite element code ULCA (Ultimate Load Capacity Assessment) adopts a degenerate concept of formulating general isoparametric shell element with a layered approach in the thickness direction. Different failure modes such as crushing, tensile cracking and reinforcement yielding are recognised for various problems. The structure fails by crushing of concrete when the concrete strain/stress reaches the ultimate stress or strain of concrete. Material nonlinearities as a result of tension cracking, tension stiffening between reinforcement and concrete in cracked region and yielding of reinforcement are considered along with geometric nonlinearity. Thus with this code it is possible to predict the pressure at which the first cracking, first through thickness cracking, first yielding of reinforcement occurs. After validating the code with few bench mark problems for different failure modes a reinforced concrete nuclear containment is analysed for its ultimate capacity and the results are matched with the published results. Further the ultimate load capacity of outer containment wall of Narora Atomic Power Station is predicted. It is observed that containment fails in membrane region and has a sufficient margin against design pressure. (author). 9 refs., 56 figs., 3 tabs., 1 appendix with 4 tabs

Effect of reinforcement on plastic limit loads of branch junctions

International Nuclear Information System (INIS)

Kim, Yun-Jae; Myeong, Man-Sik; Yoon, Kee-Bong

2009-01-01

This paper provides effects of reinforcement shape and area on plastic limit loads of branch junctions under internal pressure and in-plane/out-of-plane bending, via detailed three-dimensional finite element limit analysis assuming elastic-perfectly plastic material behaviour. It is found that reinforcement is most effective when (in-plane/out-of-plane) bending is applied to the branch pipe. When bending is applied to the run pipe, reinforcement is less effective when bending is applied to the branch pipe. The reinforcement effect is the least effective for internal pressure.

Nondestructive evaluation of reinforced plastics by a radiometric measurement technique

International Nuclear Information System (INIS)

Entine, Gerald; Afshari, Sia; Verlinden, Matt

1990-01-01

The demand for new high-performance plastics has greatly increased with advances in the performance characteristics of sophisticated reinforced engineering resins. However, conventional methods for the evaluation of the glass and filler contents of reinforced plastics are destructive, labor intensive, and time consuming. We have developed a new instrument, to address this problem, which provides for the rapid, accurate, and nondestructive measurement of glass or filler content in reinforced plastics. This instrument utilizes radiation transmission and scattering techniques for analytical measurement of glass, graphite and other fillers used in reinforced plastics. (author)

Structural Applications of Fibre Reinforced Concrete in the Czech Republic

Science.gov (United States)

Kohoutková, A.; Broukalová, I.

2017-09-01

The paper presents improvement of function and performance of the precast structural members by using fibre reinforced concrete (FRC) instead of ordinary reinforced concrete and attempts to transfer innovative technologies from laboratory in academic sphere into real industrial production which is cost-effective and brings about savings of labour and material. Three examples of successful technology transfer are shown - application of FRC in an element without common rebar reinforcement, in the element with steel rebar reinforcement and SFRC pre-tensioned structural element. Benefits of FRC utilization are discussed.

A Comparison of Escalating versus Fixed Reinforcement Schedules on Undergraduate Quiz Taking

Science.gov (United States)

Mahoney, Amanda

2017-01-01

Drug abstinence studies indicate that escalating reinforcement schedules maintain abstinence for longer periods than fixed reinforcement schedules. The current study evaluated whether escalating reinforcement schedules would maintain more quiz taking than fixed reinforcement schedules. During baseline and for the control group, bonus points were…

Neural Basis of Reinforcement Learning and Decision Making

Science.gov (United States)

Lee, Daeyeol; Seo, Hyojung; Jung, Min Whan

2012-01-01

Reinforcement learning is an adaptive process in which an animal utilizes its previous experience to improve the outcomes of future choices. Computational theories of reinforcement learning play a central role in the newly emerging areas of neuroeconomics and decision neuroscience. In this framework, actions are chosen according to their value functions, which describe how much future reward is expected from each action. Value functions can be adjusted not only through reward and penalty, but also by the animal’s knowledge of its current environment. Studies have revealed that a large proportion of the brain is involved in representing and updating value functions and using them to choose an action. However, how the nature of a behavioral task affects the neural mechanisms of reinforcement learning remains incompletely understood. Future studies should uncover the principles by which different computational elements of reinforcement learning are dynamically coordinated across the entire brain. PMID:22462543

Carbon fiber reinforced asphalt concrete

International Nuclear Information System (INIS)

Jahromi, Saeed G.

2008-01-01

Fibers are often used in the manufacture of other materials. For many years, they have been utilized extensively in numerous applications in civil engineering. Fiber-reinforcement refers to incorporating materials with desired properties within some other materials lacking those properties. Use of fibers is not a new phenomenon, as the technique of fiber-reinforced bitumen began early as 1950. In all industrialized countries today, nearly all concretes used in construction are reinforced. A multitude of fibers and fiber materials are being introduced in the market regularly. The present paper presents characteristics and properties of carbon fiber-reinforced asphalt mixtures, which improve the performance of pavements. To evaluate the effect of fiber contents on bituminous mixtures, laboratory investigations were carried out on the samples with and without fibers. During the course of this study, various tests were undertaken, applying Marshall Test indirect tensile test, creep test and resistance to fatigue cracking by using repeated load indirect tensile test. Carbon fiber exhibited consistency in results and as such it was observed that the addition of fiber does affect the properties of bituminous mixtures, i.e. an increase in its stability and decrease in the flow value as well as an increase in voids in the mix. Results indicate that fibers have the potential to resist structural distress in pavement, in the wake of growing traffic loads and thus improve fatigue by increasing resistance to cracks or permanent deformation. On the whole, the results show that the addition of carbon fiber will improve some of the mechanical properties like fatigue and deformation in the flexible pavement. (author)

Mastocitosis sistémica: repercusión ósea

Directory of Open Access Journals (Sweden)

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.

Atomically Thin Mica Flakes and Their Application as Ultrathin Insulating Substrates for Graphene

NARCIS (Netherlands)

Castellanos-Gomez, Andres; Wojtaszek, Magdalena; Tombros, Nikolaos; Agrait, Nicolas; van Wees, Bart J.; Rubio-Bollinger, Gabino; Agraït, Nicolás

2011-01-01

By mechanical exfoliation, it is possible to deposit atomically thin mica flakes down to single-monolayer thickness on SiO(2)/Si wafers. The optical contrast of these mica flakes on top of a SiO(2)/Si substrate depends on their thickness, the illumination wavelength, and the SiO(2) substrate

The improved design method of shear strength of reinforced concrete beams without transverse reinforcement

Directory of Open Access Journals (Sweden)

Vegera Pavlo

2017-12-01

Full Text Available In this article, results of experimental testing of reinforced concrete beams without transverse shear reinforcement are given. Three prototypes for improved testing methods were tested. The testing variable parameter was the shear span to the effective depth ratio. In the result of the tests we noticed that bearing capacity of RC beams is increased with the decreasing shear span to the effective depth ratio. The design method according to current codes was applied to test samples and it showed a significant discrepancy results. Than we proposed the improved design method using the adjusted value of shear strength of concrete CRd,c. The results obtained by the improved design method showed satisfactory reproducibility.

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 ...

Midbroken Reinforced Concrete Shear Frames Due to Earthquakes

DEFF Research Database (Denmark)

Köylüoglu, H. U.; Cakmak, A. S.; Nielsen, Søren R. K.

A non-linear hysteretic model for the response and local damage analyses of reinforced concrete shear frames subject to earthquake excitation is proposed, and, the model is applied to analyse midbroken reinforced concrete (RC) structures due to earthquake loads. Each storey of the shear frame...

Reinforcement learning in complementarity game and population dynamics.

Science.gov (United States)

Jost, Jürgen; Li, Wei

2014-02-01

We systematically test and compare different reinforcement learning schemes in a complementarity game [J. Jost and W. Li, Physica A 345, 245 (2005)] played between members of two populations. More precisely, we study the Roth-Erev, Bush-Mosteller, and SoftMax reinforcement learning schemes. A modified version of Roth-Erev with a power exponent of 1.5, as opposed to 1 in the standard version, performs best. We also compare these reinforcement learning strategies with evolutionary schemes. This gives insight into aspects like the issue of quick adaptation as opposed to systematic exploration or the role of learning rates.

Effects of Video Games as Reinforcers for Computerized Addition Performance.

Science.gov (United States)

Axelrod, Saul; And Others

1987-01-01

Four 2nd-grade students completed addition problems on a computer, using video games as reinforcers. Two variable ratio schedules of reinforcement failed to increase student accuracy or the rate of correct responses. In a no-games reinforcement condition, students had more opportunities to respond and had a greater number of correct answers.…

Advance study of fiber-reinforced self-compacting concrete

International Nuclear Information System (INIS)

Mironova, M.; Ivanova, M.; Naidenov, V.; Georgiev, I.; Stary, J.

2015-01-01

Incorporation in concrete composition of steel macro- and micro – fiber reinforcement with structural function increases the degree of ductility of typically brittle cement-containing composites, which in some cases can replace completely or partially conventional steel reinforcement in the form of rods and meshes. Thus, that can reduce manufacturing, detailing and placement of conventional reinforcement, which enhances productivity and economic efficiency of the building process. In this paper, six fiber-reinforced with different amounts of steel fiber cement-containing self-compacting compositions are investigated. The results of some of their main strength-deformation characteristics are presented. Advance approach for the study of structural and material properties of these type composites is proposed by using the methods of industrial computed tomography. The obtained original tomography results about the microstructure and characteristics of individual structural components make it possible to analyze the effective macro-characteristics of the studied composites. The resulting analytical data are relevant for the purposes of multi-dimensional modeling of these systems. Multifactor structure-mechanical analysis of the obtained with different methods original scientific results is proposed. It is presented a conclusion of the capabilities and effectiveness of complex analysis in the studies to characterize the properties of self-compacting fiber-reinforced concrete

Advance study of fiber-reinforced self-compacting concrete

Science.gov (United States)

Mironova, M.; Ivanova, M.; Naidenov, V.; Georgiev, I.; Stary, J.

2015-10-01

Incorporation in concrete composition of steel macro- and micro - fiber reinforcement with structural function increases the degree of ductility of typically brittle cement-containing composites, which in some cases can replace completely or partially conventional steel reinforcement in the form of rods and meshes. Thus, that can reduce manufacturing, detailing and placement of conventional reinforcement, which enhances productivity and economic efficiency of the building process. In this paper, six fiber-reinforced with different amounts of steel fiber cement-containing self-compacting compositions are investigated. The results of some of their main strength-deformation characteristics are presented. Advance approach for the study of structural and material properties of these type composites is proposed by using the methods of industrial computed tomography. The obtained original tomography results about the microstructure and characteristics of individual structural components make it possible to analyze the effective macro-characteristics of the studied composites. The resulting analytical data are relevant for the purposes of multi-dimensional modeling of these systems. Multifactor structure-mechanical analysis of the obtained with different methods original scientific results is proposed. It is presented a conclusion of the capabilities and effectiveness of complex analysis in the studies to characterize the properties of self-compacting fiber-reinforced concrete.

Advance study of fiber-reinforced self-compacting concrete

Energy Technology Data Exchange (ETDEWEB)

Mironova, M., E-mail: mirona@imbm.bas.bg; Ivanova, M., E-mail: magdalena.ivanova@imbm.bas.bg; Naidenov, V., E-mail: valna53@mail.bg [Institute of Mechanics, Bulgarian Academy of Sciences, Acad. G. Bonchev str., bl. 4, Sofia 1113 (Bulgaria); Georgiev, I., E-mail: ivan.georgiev@parallel.bas.bg [Institute of Information and Communication Technologies & Institute of Mathematics and Informatics, Bulgarian Academy of Sciences, Acad. G. Bonchev str., Sofia 1113 (Bulgaria); Stary, J., E-mail: stary@ugn.cas.cz [Institute of Geonics Czech Academy of Sciences, Studentska str., Ostrava 1768 (Czech Republic)

2015-10-28

Incorporation in concrete composition of steel macro- and micro – fiber reinforcement with structural function increases the degree of ductility of typically brittle cement-containing composites, which in some cases can replace completely or partially conventional steel reinforcement in the form of rods and meshes. Thus, that can reduce manufacturing, detailing and placement of conventional reinforcement, which enhances productivity and economic efficiency of the building process. In this paper, six fiber-reinforced with different amounts of steel fiber cement-containing self-compacting compositions are investigated. The results of some of their main strength-deformation characteristics are presented. Advance approach for the study of structural and material properties of these type composites is proposed by using the methods of industrial computed tomography. The obtained original tomography results about the microstructure and characteristics of individual structural components make it possible to analyze the effective macro-characteristics of the studied composites. The resulting analytical data are relevant for the purposes of multi-dimensional modeling of these systems. Multifactor structure-mechanical analysis of the obtained with different methods original scientific results is proposed. It is presented a conclusion of the capabilities and effectiveness of complex analysis in the studies to characterize the properties of self-compacting fiber-reinforced concrete.

Visual reinforcement shapes eye movements in visual search.

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