Monitoreo de cambios en la densidad de cobertura forestal en bosque templado usando fotografías aéreas digitales de alta resolución

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José López García

2016-08-01

Full Text Available Se utilizaron series multitemporales de fotografías aéreas digitales de alta resolución de pequeño formato para evaluar los cambios en la densidad de cobertura forestal en un bosque templado. Una combinación de técnicas convencionales y adaptadas de fotogrametría y fotointerpretación fueron utilizadas para establecer un método específico de evaluación.  Este método ha sido probado en un periodo de doce años (1999-2011 en la zona núcleo de la Reserva de la Biósfera Mariposa Monarca, localizada en los estados de México y Michoacán, en México, usando mosaicos ortorectificados como mapas base para evaluar cambios bienales. Las imágenes fueron fotointerpretadas de manera tradicional marcando los cambios sobre acetatos, colocados sobre las imágenes impresas, creando así nuevos polígonos. Estos fueron transferidos directamente de los acetatos al ortomosaico a través de la pantalla de la computadora, usando al menos tres puntos de control, cumpliendo así con el principio de triangulación radial. El bosque fue separado en las siguientes clases de cobertura forestal: cerrada, semi-cerrada, semi-abierta, abierta y deforestada. La evaluación en la exactitud en la clasificación de densidad de cobertura fue estimada a través de muestreos en campo, empleando matrices de confusión, siendo del 95%. A partir de 2003, este método ha sido utilizado para determinar el pago por servicios ambientales. Dicho pago, junto con una gran interacción con las comunidades, se ha traducido en una reducción en la degradación forestal y la deforestación en la zona núcleo de la Reserva.

A Study of Array Direction HDPE Fiber Reinforced Mortar

Science.gov (United States)

Kamsuwan, Trithos

2018-02-01

This paper presents the effect of array direction HDPE fiber using as the reinforced material in cement mortar. The experimental data were created reference to the efficiency of using HDPE fiber reinforced on the tensile properties of cement mortar with different high drawn ratio of HDPE fibers. The fiber with the different drawn ratio 25x (d25 with E xx), and 35x (d35 with E xx) fiber volume fraction (0%, 1.0%, 1.5%) and fiber length 20 mm. were used to compare between random direction and array direction of HDPE fibers and the stress - strain displacement relationship behavior of HDPE short fiber reinforced cement mortar were investigated. It was found that the array direction with HDPE fibers show more improved in tensile strength and toughness when reinforced in cement mortar.

Thermoforming of HDPE

Science.gov (United States)

McKelvey, David; Menary, Gary; Martin, Peter; Yan, Shiyong

2017-10-01

The thermoforming process involves a previously extruded sheet of material being reheated to a softened state below the melting temperature and then forced into a mould either by a plug, air pressure or a combination of both. Thermoplastics such as polystyrene (PS) and polypropylene (PP) are commonly processed via thermoforming for products in the packaging industry. However, high density polyethylene (HDPE) is generally not processed via thermoforming and yet HDPE is extensively processed throughout the packaging industry. The aim of this study was to investigate the potential of thermoforming HDPE. The objectives were to firstly investigate the mechanical response under comparable loading conditions and secondly, to investigate the final mechanical properties post-forming. Obtaining in-process stress-strain behavior during thermoforming is extremely challenging if not impossible. To overcome this limitation the processing conditions were replicated offline using the QUB biaxial stretcher. Typical processing conditions that the material will experience during the process are high strain levels, high strain rates between 0.1-10s-1 and high temperatures in the solid phase (1). Dynamic Mechanical Analysis (DMA) was used to investigate the processing range of the HDPE grade used in this study, a peak in the tan delta curve was observed just below the peak melting temperature and hence, a forming temperature was selected in this range. HPDE was biaxially stretched at 128°C at a strain rate of 4s-1, under equal biaxial deformation (EB). The results showed a level of biaxial orientation was induced which was accompanied by an increase in the modulus from 606 MPa in the non-stretched sample to 1212MPa in the stretched sample.

ALTAS DENSIDADES DE PLANTIO NA CULTURA DO ABACAXI CV. SMOOTH CAYENNE, SOB CONDIÇÕES DE SEQUEIRO HIGH PLANTING DENSITY FOR THE SMOOTH CAYENNE PINEAPPLE CROP, GROWN UNDER RAINFED CONDITIONS

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LUCIANA LIMA DE ALMEIDA SANTANA

2001-08-01

Full Text Available No Brasil têm-se usado densidades de plantio relativamente baixas para a obtenção de frutos grandes, com reflexos negativos na produtividade da cultura do abacaxi. No entanto, frutos cada vez menores têm sido comercializados no mercado internacional, o que poderá também ocorrer no mercado nacional. Este trabalho teve o objetivo de avaliar o efeito de altas densidades em sistemas de plantio em filas duplas sobre a produção quantitativa e qualitativa de abacaxi cv. Smooth Cayenne, sob condições de sequeiro. Densidades de plantio, variando de 51.280 plantas/ha a 100.000 plantas/ha, foram estudadas em delineamento experimental de blocos casualizados, com cinco repetições e doze tratamentos, distribuídos em esquema fatorial 4 x 3, correspondendo a quatro combinações de espaçamentos entre linhas duplas e entre linhas simples na fila dupla (90cm x 40 cm, 90 cm x 30 cm, 80 cm x 30 cm , 70 cm x 30 cm e três espaçamentos entre plantas nas linhas de plantio (30 cm, 25 cm, 20 cm. A análise de variância determinou diferença estatística apenas para a produtividade, em função do espaçamento entre plantas na linha de plantio, sendo mais elevada para o espaçamento de 20 cm. O peso do fruto, as suas dimensões e a sua qualidade (açucares, acidez, teor de suco, relação açúcares/acidez não foram significativamente influenciados pelas densidades de plantio estudadas, mantendo-se dentro dos padrões da cultivar. Para cada aumento de 10.000 plantas por hectare, a produtividade cresceu em 8,27 t/ha e o peso médio do fruto caiu 102 g. Nas condições ambientais dos Tabuleiros Costeiros do Norte da Bahia, a cultura do abacaxi cv. Smooth Cayenne apresenta potencial para uso em altas densidades de plantio, mesmo em cultivo de sequeiro, podendo-se atingir produtividade acima de 80t/ha e peso médio do fruto superior a 1,0 kg.In Brazil, relatively low planting densities have been used to obtain large fruits, with negative effects on pineapple

Toughening mechanisms in interfacially modified HDPE/thermoplastic starch blends.

Science.gov (United States)

Taguet, Aurélie; Bureau, Martin N; Huneault, Michel A; Favis, Basil D

2014-12-19

The mechanical behavior of polymer blends containing 80 wt% of HDPE and 20 wt% of TPS and compatibilized with HDPE-g-MA grafted copolymer was investigated. Unmodified HDPE/TPS blends exhibit high fracture resistance, however, the interfacial modification of those blends by addition of HDPE-g-MA leads to a dramatic drop in fracture resistance. The compatibilization of HDPE/TPS blends increases the surface area of TPS particles by decreasing their size. It was postulated that the addition of HDPE-g-MA induces a reaction between maleic anhydride and hydroxyl groups of the glycerol leading to a decrease of the glycerol content in the TPS phase. This phenomenon increases the stiffness of the modified TPS particles and stiffer TPS particles leading to an important reduction in toughness and plastic deformation, as measured by the EWF method. It is shown that the main toughening mechanism in HDPE/TPS blends is shear-yielding. This article demonstrates that stiff, low diameter TPS particles reduce shear band formation and consequently decrease the resistance to crack propagation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Studies on the suitability of HDPE material for gill nets

OpenAIRE

Subramania Pillai, N.; Boopendranath, M.R.; Kunjipalu, K.K.

1989-01-01

The suitability of HDPE yarn and HDPE twine in place of nylon for gill nets has been studied. As regards total catch nylon gill net is found to be better than HDPE nets. However, statistical analysis of the catch in respect of quality fishes shows that HDPE yarn nets are equally efficient as nylon nets.

Characterization of the microporous HDPE film with alpha alumina

International Nuclear Information System (INIS)

Park, Jong Seok; Sung, Hae Jun; Gwon, Hui Jeong; Lim, Youn Mook; Nho, Young Chang

2010-01-01

The effects of the addition of the alpha alumina on the properties of the microporous high density polyethylene (HDPE) films were investigated. The particle size and the specific surface area of alpha alumina were 400 nm and 7.3 m 2 g -1 . The HDPE and the alpha alumina were mixed to obtain the precursor film in the twin extruder. The precursor films were uni-axially stretched up to 600% in oven 120 .deg. C and then the stretched HDPE films were irradiated by gamma rays. The pore volume of the microporous HDPE films was increased with an increasing content of the alpha alumina. The mechanical characteristics of the microporous HDPE films were increased with a content of alpha alumina up to 15%, but decreased at 20%. The electrochemical stability of the microporous HDPE film containing alpha alumia was increased with an increased irradiation dose up ti 50 kGy

Forensic characterization of HDPE pipes by DSC.

Science.gov (United States)

Sajwan, Madhuri; Aggarwal, Saroj; Singh, R B

2008-03-05

The melting behavior of 28 high density polyethylene (HDPE) pipe samples manufactured and supplied by 13 different manufacturers in India was examined by 'differential scanning calorimetry (DSC)' to find out if this parameter could be used in differentiating between these HDPE pipe samples which are chemically the same and being manufactured by different manufacturer. The results indicate that the melting temperature may serve as the useful criteria for differentiating HDPE (i) pipe samples from different sources and (ii) samples of different diameter from the same source.

Influence of nanoclay on properties of HDPE/wood composites

Science.gov (United States)

Yong Lei; Qinglin Wu; Craig M. Clemons; Fei Yao; Yanjun Xu

2007-01-01

Composites based on high density polyethylene (HDPE), pine flour, and organic clay were made by melt compounding and then injection molding. The influence of clay on crystallization behavior, mechanical properties, water absorption, and thermal stability of HDPE/pine composites was investigated. The HDPE/pine composites containing exfoliated clay were made by a two-...

Características de compósitos laminados manufaturados com polietileno de alta densidade (PEAD e diferentes proporções de casca de arroz e partículas de madeira

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Dalva Teresinha Pauleski

2007-01-01

Full Text Available The objective of this work was to analyse the feasibility of the utilization of rice husks and wood particles in the manufacture of wood plastic composites, in a way similar to particleboard fabrication. The composites were made with rice husks and Eucalyptus grandis wood particles, pure or mixed, in proportions of 0, 25, 50, 75 and 100% of ovendry weight. High density polyethylene (HDPE was used as matrix in the manufacture in three proportions: 60, 75, and 90%. Bending properties, internal bond, water absorption and thickness swelling after 24 hours of water soaking and after 15 soaking cycles were evaluated. The values of bending properties were influenced by the density of the composite. In the case of internal bond, the values were within the limits established by commercial particleboard standards, being the HDPE proportion the parameter of higher correlation with this property. Rice husk caused lower thickness swelling and, independently of the type of raw material utilised, the values decreased with the increase of HDPE. Combinations with larger percentages of HDPE presented minimal values or, in some cases, null of water absorption. For the water absorption and thickness swelling after 15 cycles the behavior was similar to that of the 24 hour period. Results allowed concluding that the composites made with HDPE, rice husks and wood particles pure or mixed present good quality, evidencing the adequacy of these raw material and process in manufacturing this type of panel.

Influence of blending sequence on the rheological behavior of HDPE/LLDPE/MMT nano composites; Influencia da sequencia de mistura no comportamento reologico de nanocompositos HDPE/LLDPE/MMT

Energy Technology Data Exchange (ETDEWEB)

Passador, F.R.; Pessan, L.A., E-mail: fabiopassador@gmail.co [Universidade Federal de Sao Carlos (DEMA/UFSCAR), SP (Brazil). Dept. de Engenharia de Materiais; Ruvolo Filho, A. [Universidade Federal de Sao Carlos (PPGCEM/UFSCAR), SP (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais

2010-07-01

The blending sequence affects the rheological behavior and the morphology formation of the nanocomposites. In this work, the blending sequences were explored to see its influence in the rheological behavior of HDPE/LLDPE/MMT nanocomposites. The nanocomposites were obtained by melt-intercalation using HDPE-g-MA as a compatibilizer in a torque rheometer (Haake Rheomix 600p at 180 deg C and rotor speed of 80rpm) and five blending sequences were studied. The materials structures were characterized by wide angle X-ray diffraction (WAXD) and by rheological properties. The nanoclay's addition increased the shear viscosity at low shear rates, changing the behavior of HDPE/LLDPE matrix to a Bingham model behavior with an apparent yield stress. Intense interactions were obtained for the blending sequence where HDPE and HDPE-g-MA were first reinforced with organoclay and then the HDPE/HDPE-g-MA/organoclay nanocomposite was later blended with LLDPE. (author)

75 FR 23263 - Alta Wind I, LLC; Alta Wind II, LLC; Alta Wind III, LLC; Alta Wind IV, LLC; Alta Wind V, LLC...

Science.gov (United States)

2010-05-03

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. EL10-62-000] Alta Wind I, LLC; Alta Wind II, LLC; Alta Wind III, LLC; Alta Wind IV, LLC; Alta Wind V, LLC; Alta Wind VI, LLC; Alta Wind VII, LLC; Alta Wind VIII, LLC; Alta Windpower Development, LLC; TGP Development Company, LLC...

77 FR 29633 - Alta Wind VII, LLC, Alta Wind IX, LLC, Alta Wind X, LLC, Alta Wind XI, LLC, Alta Wind XII, LLC...

Science.gov (United States)

2012-05-18

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. EL12-68-000] Alta Wind VII, LLC, Alta Wind IX, LLC, Alta Wind X, LLC, Alta Wind XI, LLC, Alta Wind XII, LLC, Alta Wind XIII, LLC, Alta Wind XIV, LLC, Alta Wind XV, LLC, Alta Windpower Development, LLC, TGP Development Company, LLC...

Densidad y anatomia de la madera en familias mejoradas de sauces en Argentina

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Silvia Monteoliva

2013-12-01

Full Text Available El objetivo del trabajo fue la evaluación de densidad y anatomía de la madera en siete familias de sauces, con vistas a seleccionar clones aptos para la producción de madera para usos sólidos y papel. Se cruzaron progenitores de cinco especies de sauces (S. babylonica, S. alba, S. nigra, S. amygdaloides y S. matsudana, obteniéndose 1800 individuos producto de cruzamientos controlados y polinización abierta, dentro del programa de mejoramiento de sauces del INTA. A los 34 meses se efectuó una primera selección por criterios de crecimiento, sanidad y forma. De esta primera fase de mejoramiento se seleccionaron 218 genotipos sobre los cuales se evaluaron las características anatómicas cuantitativas y la densidad de la madera. Los resultados indican que ninguna familia presenta buenos resultados en todas las propiedades. En una selección priorizando el vigor, la familia 08.09 presentó las siguientes características: buen crecimiento en diámetro (6,1 cm, fibras largas y de pared gruesa (850 µm y 2,22 µm, pocos vasos (94.mm-2 y densidad intermedia a baja (350 kg.m-3. Priorizando el rendimiento, material fibroso e indirectamente la resistencia, las familias 08.01 y 08.07 presentaron: densidad relativamente alta (403 - 397 kg.m-3, fibras largas (836 - 864 µm, vasos pequeños (46 - 45 µm y bajo crecimiento en diámetro (3 - 2,85 cm. Los cruzamientos donde intervienen las especies Salix nigra, S. amygdaloides y S. matsudana se destacaron ya que presentan buenos crecimientos y las mejores combinaciones xilológicas para diferentes destinos industriales.

Structural analysis of nanocomposites based on HDPE/EPDM blends.

Science.gov (United States)

Zitzumbo, Roberto; Alonso, Sergio; Avalos, Felipe; Ortiz, José C; López-Manchado, Miguel A; Arroyo, Miguel

2006-02-01

Intercalated and exfoliated nanocomposites based on HDPE and EPDM blends with an organoclay have been obtained through the addition of EPDM-g-MA as a compatibilizer. The combined effect of clay and EPDM-g-MA on the rheological behaviour is very noticeable with a sensible increase in viscosity which suggests the formation of a structural net of percolation induced by the presence of intercalated and exfoliated silicate layer. As deduced from rheological studies, a morphology based on nanostructured micro-domains dispersed in HDPE continuous phase is proposed for EPDM/HDPE blend nanocomposites. XRD and SEM analysis suggest that two different transport phenomena take simultaneously place during the intercalation process in the melt. One due to diffusion of HDPE chains into the tactoid and the other to diffusion of EPDM-g-MA into the silicate galleries.

Effect of aging in HDPE blended with DEM in decalin

International Nuclear Information System (INIS)

Silva, P.; Albano, C.; Karam, A.; Vargas, M.G.; Perera, R.

2006-01-01

Electron paramagnetic resonance (EPR) was used to study the effect of aging on irradiated samples of high-density polyethylene (HDPE) blended with diethyl maleate (DEM) in different proportions. Initially, we synthesize the HDPE using bis-(cyclopentadienyl) zirconium dichloride and P-MAO. The functionalization of the synthesized HDPE was carried out in a 10% weight/vol of polyethylene in decalin solution using different percentages of diethyl maleate (5, 10, 15 and 30% in weight). The samples were irradiated at 5, 15 and 30 kGy. An exponential decay in the total free radicals concentration was observed in the pure HDPE sample at the 15 and 30 kGy irradiation doses, as it was expected. For the 15 and 30 kGy irradiation doses the HDPE blended with 15 and 30% of DEM in decalin shows an increase in the total free radical concentrations as the storage time is increased. This behavior has been interpreted in terms of trapped free radicals. (Author)

Calibrated Pulse-Thermography Procedure for Inspecting HDPE

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Mohammed A. Omar

2008-01-01

Full Text Available This manuscript discusses the application of a pulse-thermography modality to evaluate the integrity of a high-density polyethylene HDPE joint for delamination, in nonintrusive manner. The inspected HDPE structure is a twin-cup shape, molded through extrusion, and the inspection system comprises a high-intensity, short-duration radiation pulse to excite thermal emission; the text calibrates the experiment settings (pulse duration, and detector sampling rate to accommodate HDPE bulks thermal response. The acquired thermal scans are processed through new contrast computation named “self-referencing”, to investigate the joint tensile strength and further map its adhesion interface in real-time. The proposed system (hardware, software combination performance is assessed through an ultrasound C-scan validation and further benchmarked using a standard pulse phase thermography (PPT routine.

Sintesis Bahan Dasar Tibial Tray Berbasis HDPE Yang Diperkuat Dengan Iradiasi Gamma

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Sulistioso Giat S.

2014-04-01

Full Text Available Tibial tray yang sudah komersil dibuat dari Polimer Ultra High Molecular Weight Polyethylene (UHMWPE tetapi harganya sangat mahal. Oleh karena itu pada penelitian ini digunakan polimer High Density Polyethylene (HDPE untuk pembuatan tibial tray karena harganya yang lebih murah dan memiliki kemiripan sifat dengan UHMWPE. HDPE dibuat dengan dua metode, yaitu metode hot press dan pemanasan tanpa tekanan (PTT. UHMWPE dengan metode hot press digunakan sebagai pembanding. Metode hot press dilakukan pada suhu 180 °C dan diberi tekanan sebesar 200 kg/cm2. Sedangkan metode pemanasan tanpa tekanan (PTT dilakukan di dalam oven pada suhu 180°C. Film tipis UHMWPE dan sampel HDPE yang dihasilkan dari kedua metode tersebut, kemudian diiradiasi sinar gamma dengan variasi dosis 0, 100, 200, 300 dan 500 kGy. Karakterisasi mencakup analisis morfologi dengan Scanning Electron Microscope (SEM, uji kekerasan, kekuatan tarik, dan derajat kristalinitas. Semakin tinggi dosis radiasi, maka kekerasan dan derajat kristalinitas semakin meningkat, tetapi kekuatan tarik semakin menurun. Dosis radiasi untuk sampel HDPE yang optimum , adalah 100 kGy untuk HDPE yang dibuat dengan metoda hot press, pada kondisi ini HDPE mempunyai kekuatan mekanik mendekati nilai kekuatan mekanik UHMWPE, sedangkan HDPE yang dibuat dengan metode PTT kekuatan mekaniknya masih dibawah kekuatan mekanik HDPE yang dibuat dengan metoda hot press 

Preparations and thermal properties of micro- and nano-BN dispersed HDPE composites

International Nuclear Information System (INIS)

Jung, Jinwoo; Kim, Jaewoo; Uhm, Young Rang; Jeon, Jae-Kyun; Lee, Sol; Lee, Hi Min; Rhee, Chang Kyu

2010-01-01

The thermal properties of micro-sized boron nitride (BN) and nano-sized BN dispersed high density polyethylene (HDPE) composites were investigated by means of differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA). Nano-BN powder was prepared by using a ball mill process before it was mixed in HDPE. To enhance the dispersivity of nano-BN in the polymer matrix, the surfaces of the nano-particles were treated with low density polyethylene (LDPE) which was dissolved in the cyclohexane solvent. The average particle sizes of micro-BN powder and LDPE coated nano-BN powder were ∼10 μm and ∼100 nm respectively. Dispersion and distribution of 5 wt% and 20 wt% of micro-BN and nano-BN respectively mixed in HDPE were observed by using the scanning electron microscope (SEM). According to the thermal analyses of pure HDPE, micro-BN/HDPE, and nano-BN/HDPE, 20 wt% nano-BN/HDPE composite shows the lowest enthalpy of fusion (ΔH m ) and better thermal conductive characteristics compared to the others.

Synthesis and characterization of HDPE/N-MWNT nanocomposite films.

Science.gov (United States)

Chouit, Fairouz; Guellati, Ounassa; Boukhezar, Skander; Harat, Aicha; Guerioune, Mohamed; Badi, Nacer

2014-01-01

In this work, a series of nitrogen-doped multi-walled carbon nanotubes (N-MWCNTs) with several weight percentages (0.1, 0.4, 0.8, and 1.0 wt.%) were synthesized by catalytic chemical vapor deposition (CCVD) technique. The N-MWCNTs were first characterized and then dispersed in high-density polyethylene (HDPE) polymer matrix to form a nanocomposite. The HDPE/N-MWCNT nanocomposite films were prepared by melt mixing and hot pressing; a good dispersion in the matrix and a good N-MWCNT-polymer interfacial adhesion have been verified by scanning electron microscopy (SEM). Raman spectroscopy measurements have been performed on prepared samples to confirm the presence and nature of N-MWNTs in HDPE matrix. The X-ray diffraction (XRD) analysis demonstrated that the crystalline structure of HDPE matrix was not affected by the incorporation of the N-MWNTs.

Improvement of CNT dispersion in HDPE by acid and octadecylamine functionalizations

International Nuclear Information System (INIS)

Menezes, Beatriz Rossi Canuto de; Ferreira, Filipe Vargas; Franceschi, Wesley; Brito, Felipe Sales; Nunes, Evelyn Alves; Rodrigues, Karla Faquine; Cividanes, Luciana de Simone; Thim, Gilmar Patrocínio; Rosa, Cintia

2016-01-01

Full text: Since their discovery in 1991, carbon nanotubes (CNTs) have attracted great attention due to their extraordinary structure and exceptional mechanical properties that make them a suitable candidate for polymer-based nanocomposites reinforcement [1]. However, CNTs full potential can only be achieved with a proper dispersion in the matrix, that depends of Van der Waals interactions among CNTs due to the large surface area and the small size. These interactions decrease the CNT dispersion due to the formation of agglomerates. In order to overcome this limitation, surface functionalization with acid and alkyl groups has been used to increase the CNTs dispersion and compatibility with polymer matrix [2]. Therefore, the focus of the present work is to improve the dispersion of CNTs in high density polyethylene (HDPE) matrix through their functionalization with acid (H 2 SO 4 +HNO 3 ) and octadecylamine (ODA:CH 3 (CH 2 ) 17 NH 2 ). The CNT/HDPE nanocomposites (0.8%wt of CNTs) were prepared by mechanical agitation of the melted mixture of CNTs and HDPE and subsequent compression molding. Three nanocomposites were prepared: (1) HDPE + pristine CNTs, (2) HDPE + acid functionalized CNTs, and (3) HDPE + ODA functionalized CNTs. In order to confirm the surface treatment, CNTs was characterized by FT-IR, XPS, Raman, and TEM. The improvement in CNTs dispersion and compatibility with HDPE was verified by tensile test, microhardness, SEM-FEG. The results showed an improvement in the CNTs dispersion for HDPE with acid and ODA functionalized CNTs. The Young's modulus and Vickers microhardness increased significantly for HDPE with treated CNTs when compared with pristine CNTs. References: [1] S Iijima, Nature 354, 56-58 (1991). [2] R Ansari, S Ajori, S Rouhi, Appl Surf Sci 332, 640-647 (2015). (author)

Acoustical and mechanical behavior of HDPE/EPDM/NFU blends

OpenAIRE

Colom Fajula, Xavier; Pola, E.; Casas, P.; Nogués Morell, Francesc; Carrillo Navarrete, Fernando; Cañavate Ávila, Francisco Javier

2010-01-01

En este trabajo se pretende caracterizar el comportamiento acústico y mecánico de mezclas formadas por HDPE/EPDM/NFU. Los Neumáticos Fuera de Uso(NFU) son un gran problema debido al elevado grado de contaminación que generan. Se han analizado HDPE y HDPE/EPDM, para mejorar la compatibilidad entre la matriz y el refuerzo y obtener mejores propiedades mecánicas. Asimismo también se ha caracterizado el comportamiento acústico con el fin de conseguir incrementar el rango de aplicaciones de los mi...

Variation of Neutron Moderating Power on HDPE by Gamma Radiation

International Nuclear Information System (INIS)

Park, Kwang June; Ju, June Sik; Kang, Hee Young; Shin, Hee Sung; Kim, Ho Dong

2009-01-01

High density polyethylene (HDPE) is degraded due to a radiation-induced oxidation when it is used as a neutron moderator in a neutron counter for a nuclear material accounting of spent fuels. The HDPE exposed to the gamma-ray emitted from the fission products in a spent nuclear fuel results in a radiation-induced degradation which changes its original molecular structure to others. So a neutron moderating power variation of HDPE, irradiated by a gamma radiation, was investigated in this work. Five HDPE moderator structures were exposed to the gamma radiation emitted from a 60 Co source to a level of 10 5 -10 9 rad to compare their post-irradiation properties. As a result of the neutron measurement test with 5 irradiated HDPE structures and a neutron measuring system, it was confirmed that the neutron moderating power for the 105 rad irradiated HDPE moderator revealed the largest decrease when the un-irradiated pure one was used as a reference. It implies that a neutron moderating power variation of HDPE is not directly proportional to the integrated gamma dose rate. To clarify the cause of these changes, some techniques such as a FTIR, an element analysis and a densitometry were employed. As a result of these analyses, it was confirmed that the molecular structure of the gamma irradiated HDPEs had partially changed to others, and the contents of hydrogen and oxygen had varied during the process of a radiation-induced degradation. The mechanism of these changes cannot be explained in detail at present, and thus need further study

Study on grafting glycidyl methacrylate onto HDPE membranes by pre-irradiation graft copolymerization

International Nuclear Information System (INIS)

Tong Long; Zu Jianhua; Liu Xinwen; Sun Guisheng; Yu Chunhui

2006-01-01

Glycidyl methacrylate (GMA) was grafted onto HDPE membranes by pre-irradiation method with 1.8 MeV E-beam and a kind of membranes having reactive epoxy groups was successfully synthesized. Effects of monomer concentration, reaction temperature and time and irradiation dose on the grafting yield were studied. Composition, thermo-property and surface morphology of the grafted membranes were studied by FTIR, DSC and Tapping-mode AFM, respectively. The FTIR measurements proved the synthesized copolymer is HDPE-g-GMA. The DSC results indicated the grafted HDPE's melting temperature (T m ) and heat of fusion (ΔH f ( HDPE) ) which was reduced with increasing grafting yield. The AFM images indicated that surface of the HDPE-g-GMA membranes was rougher than the virgin HDPE. (authors)

Modification of HDPE by γ ray radiation in oxygen atmosphere and blend with PA6

International Nuclear Information System (INIS)

Ding Yunsheng; Shi Tiejun; Zhang Zhicheng; Hu Keliang

2002-01-01

A study on the oxidation of high density polyethylene (HDPE) by γ ray irradiation in oxygen atmosphere has been made. The influence of irradiated time on the oxidation has been investigated with the help of Fourier Transform Infrared-Photoacoustics Spectroscopy (FTIR-PAS). Results of FTIR-PAS show after irradiation groups like -C=O, -O-C-O-, O=C-O- were introduced into the HDPE. Although the γ ray has powerful penetrability, the oxidation mainly takes place on the surface of HDPE. after 4 h irradiation in oxygen (dose rate 66 Gy/min.), -C=O is the main group which was introduced into the surface of HDPE. Lengthening the irradiation process makes the pre-produced oxidized section in HDPE surface continue their reactions to yield some oxidation products with the structures of -O-C-O-, O=C-O- and so on. FTIR shows there are reactions or week interaction like hydrogen bond between the irradiated HDPE and PA6 in the binary blends, this is helpful to increase the compatibility of the phase of HDPE and polyamide-6 (PA6) in the blend. Scanning Electron Microscope (SEM) result shows that the interface between HDPE matrix and PA6 domains is much clear and smoother in 0γHDPE/PA6 blends than in 4γHDPE/PA6 and 7γHDPE/PA6 blends. These suggested the miscibility of PA6 and HDPE was improved after HDPE irradiating in oxygen by γ ray radiation

Dynamic Viscoelastic Behavior and Phase Morphology of HIPS/HDPE Blends

OpenAIRE

LIU Jing-ru; XIA Yang-yang; GAO Li-qun; YU Qiang

2017-01-01

The dynamic viscoelastic behavior and phase morphology of high impact polystyrene (HIPS)/high density polyethylene (HDPE) blends were investigated by dynamic rheological test and scanning electron microscopy (SEM). The compatibilizing effect of 1%(mass fraction, same as below) micron-CaCO3 and nano-CaCO3 on HIPS/HDPE(30/70) immiscible blend was compared. The results indicate that the complex viscosity and storage modulus of HIPS/HDPE blends at low frequencies show positive deviation from the ...

Higher glandular trichome density in tomato leaflets and repellence to spider mites Alta densidade de tricomas glandulares em tomateiro e aumento da repelência a ácaros rajados

Directory of Open Access Journals (Sweden)

Wilson Roberto Maluf

2007-09-01

ácaro na superfície do folíolo de tomateiro, após 20, 40 e 60 min. Os biotestes de repelência ao ácaro rajado demonstraram que a alta densidade de tricomas glandulares, especialmente de tipo VI, influencia negativamente a distância média percorrida pelos ácaros na superfície do folíolo. Plantas com número de tricomas glandulares elevado podem ser selecionadas para se obterem genótipos com alto índice de repelência aos ácaros.

Compatibilization of recycled and virgin PET with radiation-oxidized HDPE

International Nuclear Information System (INIS)

Burillo, Guillermina; Herrera-Franco, Pedro; Vazquez, Margarito; Adem, Esbaide

2002-01-01

Blends of high-density polyethylene (HDPE), which cross-links on radiation, and both, recycled and pristine polyethylene terephtalate (PET), one of the most radiation-stable polymers, that contain aromatic groups, which are effective at dissipation of the energy of the ionizing radiation, were irradiated with gamma rays, in order to form a copolymer capable of improving the compatibility of the blend HDPE/PET. Due to the low content of the PET in the resulting copolymer, blends PET and radiation-oxidized HDPE, were also studied. The tensile and flexural properties were improved when the PET content was increased and when the HDPE was pre-irradiated; the largest increase in the mechanical properties was observed for PET contents between 10% and 20% (w/w). The improvement in the properties is believed to occur because of a percolation effect of the PET in the HDPE matrix and the radiation-improved compatibility by means of polar groups formed in the polyethylene. However, impact properties were observed to decrease when the PET content increased in spite of the irradiation

Study on HDPE Mixed with Sand as Backfilled Material on Retaining Structure

Science.gov (United States)

Talib, Z. A.

2018-04-01

The failure of the retaining wall is closely related to backfill material. Granular soils such as sand and gravel are most suitable backfill material because of its drainage properties. However two basic materials are quite heavy and contribute high amount of lateral loads. This study was to determine the effectiveness High Density Polyethylene (HDPE) as a backfill material. HDPE has a lighter weight compare to the sand. It makes HDPE has potential to be used as backfill material. The objective of this study is to identify the most effective percentage of HDPE to replace sand as a backfill material. The percentage of HDPE used in this study was 20%, 30%, 50%, 75% and also 100%. Testing involved in this study were sieve analysis test, constant head permeability test, direct shear test and relative density test. The result shows that the HDPE can be used as backfilled material and save the cost of backfill material

The influence of gamma radiation on HDPE properties for tibial tray

International Nuclear Information System (INIS)

Sulistioso, G.S.; Dewi, R.K.; Maria, C.P.; Nada, M.

2012-01-01

A research on HDPE as tibial tray in total knee joint replacement surgery has been done. The aims of this research were to characterize the influence of gamma radiation on chemical, and mechanical properties on HDPE is made by using hot press method then irradiated with various doses of gamma rays of 0 kGy, 25 kGy, 50 kGy, 75 kGy, 100 kGy, 125 kGy, and 150 kGy at a dose rate 9 kGy/h. The irradiated HDPE were tested for their chemical, and mechanical properties. The chemical properties test, involve crosslinking and free radicals. The mechanical properties test, involve hardness, tensile strength, and elongation at break. The results showed that gamma radiation from IRKA IV th category can enhance the, chemical properties of HDPE in terms of percentage and number of radical crosslinking and mechanical properties of HDPE in terms of hardness, tensile strength and elongation at break with different changes from the initial state before radiation also the optimum dose to obtain better physical, chemical, and mechanical properties of HDPE, crosslinking percentage at 99.71%; height of radical peroxide curve at 13 cm; hardness (shore A) at 94.33; modulus of elasticity at 1113.03 N/mm 2 ; yield stress at 26.38 N/mm 2 ; tensile strength at 31.11 N/mm 2 ; and elongation at break at 440.37%, so that HDPE can be used as tibial tray. (author)

Effect of EPDM-g-MAH on properties of HDPE/OBC blends

Science.gov (United States)

Li, M.; Yu, L. Y.; Li, P. F.; Bin, Y. H.; Zhang, H. J.

2017-04-01

In this paper, we take the HDPE as the matrix material, OBC as the toughening material, and EDPM-g-MAH as the compatibility agent, HDPE/OBC/EPDM-g-MAH blends were prepared by high speed mixing, melt extrusion, injection molding and so on. The effects of OBC and EPDM-g-MAH on mechanical properties, crystalline properties, fracture surface structure and rheological properties of HDPE were analyzed by universal tensile tester, melt mass flow rate test machine, DSC and SEM. Experimental results show that: with the addition of EPDM-g-MAH, the notched impact strength of the blends increased first and then decreased; HDPE/OBC blend containing 4% EPDM-g-MAH, OBC dispersion in the matrix is more uniform, particle size is significantly refined, melt flow has some improvement, Compared with HDPE/OBC blend materials, notched impact strength and elongation at break increased by 41.07% and 107.28% respectively, the toughness of the blend was greatly improved.

Influence of blending sequence on the rheological behavior of HDPE/LLDPE/MMT nano composites

International Nuclear Information System (INIS)

Passador, F.R.; Pessan, L.A.; Ruvolo Filho, A.

2010-01-01

The blending sequence affects the rheological behavior and the morphology formation of the nanocomposites. In this work, the blending sequences were explored to see its influence in the rheological behavior of HDPE/LLDPE/MMT nanocomposites. The nanocomposites were obtained by melt-intercalation using HDPE-g-MA as a compatibilizer in a torque rheometer (Haake Rheomix 600p at 180 deg C and rotor speed of 80rpm) and five blending sequences were studied. The materials structures were characterized by wide angle X-ray diffraction (WAXD) and by rheological properties. The nanoclay's addition increased the shear viscosity at low shear rates, changing the behavior of HDPE/LLDPE matrix to a Bingham model behavior with an apparent yield stress. Intense interactions were obtained for the blending sequence where HDPE and HDPE-g-MA were first reinforced with organoclay and then the HDPE/HDPE-g-MA/organoclay nanocomposite was later blended with LLDPE. (author)

Mechanical Reinforcement of Epoxy Composites with Carbon Fibers and HDPE

Science.gov (United States)

He, R.; Chang, Q.; Huang, X.; Li, J.

2018-01-01

Silanized carbon fibers (CFs) and a high-density polyethylene with amino terminal groups (HDPE) were introduced into epoxy resins to fabricate high-performance composites. A. mechanical characterization of the composites was performed to investigate the effect of CFs in cured epoxy/HDPE systems. The composites revealed a noticeable improvement in the tensile strength, elongation at break, flexural strength, and impact strength in comparison with those of neat epoxy and cured epoxy/HDPE systems. SEM micrographs showed that the toughening effect could be explained by yield deformations, phase separation, and microcracking.

Simulación y análisis de transitorios electromagnéticos de frente rápido debido a descargas atmosféricas en instalaciones eléctricas de alta tensión

OpenAIRE

Linares Vargas, Miguel Alejandro; Linares Vargas, Miguel Alejandro

2013-01-01

Uno de los problemas que afecta al diseño y operación de los sistemas eléctricos de potencia es el gran número de instalaciones eléctricas de alta tensión ubicadas en lugares con alta densidad de descargas atmosféricas, que por lo general están situados a más de 3000 msnm, como en el sistema eléctrico peruano. Por este motivo, se le ha dado gran importancia al análisis de transitorios electromagnéticos de alta frecuencia en el diseño de instalaciones de alta tensión, lo que permitirá plantear...

Efecto del color y de la densidad del polietileno de fundas para cubrir el racimo sobre dimensiones, presentación y calidad poscosecha de frutos de banano y plátano

Directory of Open Access Journals (Sweden)

Alfonso Vargas

2010-01-01

Full Text Available Se evaluó el efecto del color (azul, verde y rojo y densidad (baja y alta del polietileno de fundas protectoras del racimo de Musa en 4 experimentos de banano (Musa AAA y en 1 de plátano (Musa AAB realizados en fincas comerciales del Caribe de Costa Rica. El peso del racimo y el intervalo de días del embolse a la cosecha no difirieron entre los colores (p>0,4116 ni entre las densidades (p>0,2583 de las fundas. La apariencia del racimo presentó diferencias entre colores (p0,0669 y densidades (p>0,2370 de las fundas. La longitud del fruto central de las manos antes mencionadas tampoco presentó diferencias entre colores (p>0,1446 y solo varió con la densidad en la segunda y cuarta mano del experimento 3 (p0,0899 y entre las densidades (p>0,0606 de las fundas. El porcentaje de acidez presentó diferencias (p<0,0001 entre colores solamente en el experimento 1. Los resultados indican que generalmente, bajo las condiciones agroclimáticas y de manejo propias de Caribe costarricense, no hubo efecto del color ni de la densidad del polietileno evaluados sobre los racimos y frutos de banano y plátano.

Biodegradation of thermally treated high-density polyethylene (HDPE) by Klebsiella pneumoniae CH001.

Science.gov (United States)

Awasthi, Shraddha; Srivastava, Pratap; Singh, Pardeep; Tiwary, D; Mishra, Pradeep Kumar

2017-10-01

Biodegradation of plastics, which are the potential source of environmental pollution, has received a great deal of attention in the recent years. We aim to screen, identify, and characterize a bacterial strain capable of degrading high-density polyethylene (HDPE). In the present study, we studied HDPE biodegradation using a laboratory isolate, which was identified as Klebsiella pneumoniae CH001 (Accession No MF399051). The HDPE film was characterized by Universal Tensile Machine (UTM), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), and Atomic Force Microscope (AFM) before and after microbial incubation. We observed that this strain was capable of adhering strongly on HDPE surface and form a thick biofilm, when incubated in nutrient broth at 30 °C on 120 rpm for 60 days. UTM analysis showed a significant decrease in weight (18.4%) and reduction in tensile strength (60%) of HDPE film. Furthermore, SEM analysis showed the cracks on the HDPE surface, whereas AFM results showed an increase in surface roughness after bacterial incubation. Overall, these results indicate that K. pneumoniae CH001 can be used as potential candidate for HDPE degradation in eco-friendly and sustainable manner in the environment.

Characterization of the microporous HDPE film with a stearyl alcohol and its physical properties

International Nuclear Information System (INIS)

Park, Jong Seok; Sung, Hae Jun; Gwon, Hui Jeong; Lim, Youn Mook; Nho, Young Chang

2009-01-01

The addition effects of the stearyl alcohol (STE) on the properties of the microporous high density polyethylene (HDPE) films were investigated. STE and dibuthyl phthalate (DBP) were premixed as a codiluent. The HDPE and the codiluent were mixed to obtain the precursor film in the twin extruder. The precursor films were uni-axially stretched up to 600% in a bath 80 .deg. C and then the stretched HDPE films were irradiated by gamma rays. The pore volume and pore size on the microporous HDPE films were increased with an increasing content of STE. The mechanical characteristics of the microporous HDPE films were increased with an irradiation dose up to 50 kGy. Also, the thermal shrinkage behavior of the microporous HDPE films was decreased with an increasing radiation dose up to 50 kGy

Diversity and effectiveness of tropical mangrove soil microflora on the degradation of polythene carry bags

Directory of Open Access Journals (Sweden)

Shristi Kumar

2007-12-01

microflora en la degradación del polietileno comercial de bolsas hechas de polietileno de alta densidad (HDPE y de baja densidad (LDPE fue estudiada en el laboratorio por un periodo de ocho semanas. La biodegradación fue medida en términos de pérdida de peso, la cual indicó una disminución del 5 %. Después de ocho semanas en el suelo de un manglar, el polietileno clase 1 y clase 3 contenía fundamentalmente Bacillus, pero en el polietileno clase 2 predominó el género Staphylococcus. Mientras que la mayoría de bacterias aisladas fueron capaces de producir enzimas hidrolíticas como la amilasa y la gelatinasa, la actividad lipolítica fue muy baja. La clase 2 (HDPE experimentó la mayor biodegradación.

Tensile strength of ramie yarn (spinning by machine)/HDPE thermoplastic matrix composites

International Nuclear Information System (INIS)

Banowati, Lies; Hadi, Bambang K.; Suratman, Rochim; Faza, Aulia

2016-01-01

Technological developments should be trooped to prevent a gap between technology and environmental sustainability, then it needs to be developed “Green technology”. In this research is making of green composites which use natural fiber ramie as reinforcement. Whereas the matrix used was HDPE (High Density Polyethylene) thermoplastic polymer which could be recycled and had a good formability and flexibility. The ramie yarns and fibers for unidirectional (0°) direction respectively were mixed with HDPE powder and processed using hot compression molding. The surface morphology was observed by SEM (Scanning Electrone Microscopy). Results showed that both tensile strength of the ramie fiber/HDPE composites increased in comparison with the ramie yarn (spinning by machine)/HDPE composites. However, the ramie yarn (spinning by machine)/HDPE composites have a good producibility for wider application. Analysis of the test results using the Weibull distribution as approaches to modeling the reliability of the specimens.

Tensile strength of ramie yarn (spinning by machine)/HDPE thermoplastic matrix composites

Energy Technology Data Exchange (ETDEWEB)

Banowati, Lies, E-mail: liesbano@gmail.com; Hadi, Bambang K., E-mail: bkhadi@ae.itb.ac.id; Suratman, Rochim, E-mail: rochim@material.itb.ac.id; Faza, Aulia [Faculty of Mechanical and Aerospace Engineering, Bandung Institute of Technology, Indonesia Jl. Ganesha 10, Bandung (Indonesia)

2016-03-29

Technological developments should be trooped to prevent a gap between technology and environmental sustainability, then it needs to be developed “Green technology”. In this research is making of green composites which use natural fiber ramie as reinforcement. Whereas the matrix used was HDPE (High Density Polyethylene) thermoplastic polymer which could be recycled and had a good formability and flexibility. The ramie yarns and fibers for unidirectional (0°) direction respectively were mixed with HDPE powder and processed using hot compression molding. The surface morphology was observed by SEM (Scanning Electrone Microscopy). Results showed that both tensile strength of the ramie fiber/HDPE composites increased in comparison with the ramie yarn (spinning by machine)/HDPE composites. However, the ramie yarn (spinning by machine)/HDPE composites have a good producibility for wider application. Analysis of the test results using the Weibull distribution as approaches to modeling the reliability of the specimens.

Suspension-like hardening behavior of HDPE and time-hardening superposition

NARCIS (Netherlands)

Roozemond, P.C.; Janssens, V.; Puyvelde, van P.C.J.; Peters, G.W.M.

2012-01-01

The rheology of solidifying high-density polyethylene (HDPE) is investigated. Experiments on an HDPE were performed with a novel RheoDSC device. Results agree quantitatively with simulations for a suspension of elastic spheres in a viscoelastic matrix except for very low values of space filling

AFM study of the morphologic change of HDPE surface photografted with glycidyl methacrylate.

Science.gov (United States)

Wang, Huiliang; Han, Jianmei

2009-05-01

The UV-induced grafting of glycidyl methacrylate (GMA) onto high-density polyethylene (HDPE) and the atomic force microscopy (AFM) study of the morphologic change of the grafted surface are reported. The grafting was carried out in GMA acetone solutions with different monomer concentrations. Grafting was much faster in a solution with a higher monomer concentration. FTIR analyses proved that GMA had been successfully grafted onto HDPE. The morphologies of grafted HDPE surfaces changed with UV irradiation time. The monomer concentration had a significant effect on the morphologies of the grafted HDPE surfaces. The HDPE surface grafted in a solution with a higher monomer concentration was much rougher than that grafted in a solution with a lower monomer concentration. The growth models of the grafted granules or clusters are also proposed.

Effects of γ-irradiation and thermal treatment of crystallinity of drawn HDPE

International Nuclear Information System (INIS)

Liu Zhanjun; Silverman, J.

1997-01-01

The effect of absorbed dose irradiated in vacuum and air on the crystallinity of drawn HDPE was studied. Experimental results show that up to 250 kGy of absorbed dose when irradiated in vacuum, the crystallinity of drawn HDPE is decreased from about 75% to about 71%, and then the increase of absorbed dose until 1000 kGy has no further effect in lowering the crystallinity; when irradiated in air, an absorbed dose of 1000 kGy has no effect on the crystallinity of drawn HDPE. The effect of temperature of thermal treatment on the crystallinity of unirradiated drawn HDPE was also investigated. At first, the crystallinity is increased with the increase of temperature of thermal treatment, at about 120 degree C, it reaches the maximum value, and then it is rapidly lowered with the further increase of temperature of thermal treatment. Based on the existence of a lot of voids and lattice defects inside the drawn HDPE, the above experimental results were explained

Enhancement of in vitro high-density polyethylene (HDPE) degradation by physical, chemical, and biological treatments.

Science.gov (United States)

Balasubramanian, V; Natarajan, K; Rajeshkannan, V; Perumal, P

2014-11-01

Partially degraded high-density polyethylene (HDPE) was collected from plastic waste dump yard for biodegradation using fungi. Of various fungi screened, strain MF12 was found efficient in degrading HDPE by weight loss and Fourier transform infrared (FT-IR) spectrophotometric analysis. Strain MF12 was selected as efficient HDPE degraders for further studies, and their growth medium composition was optimized. Among those different media used, basal minimal medium (BMM) was suitable for the HDPE degradation by strain MF12. Strain MF12 was subjected to 28S rRNA sequence analysis and identified as Aspergillus terreus MF12. HDPE degradation was carried out using combinatorial physical and chemical treatments in conjunction to biological treatment. The high level of HDPE degradation was observed in ultraviolet (UV) and KMnO4/HCl with A. terreus MF12 treatment, i.e., FT10. The abiotic physical and chemical factors enhance the biodegradation of HDPE using A. terreus MF12.

The Effect of Different Shape and Perforated rHDPE in Concrete Structures on Flexural Strength

Science.gov (United States)

Yuhazri, MY; Hafiz, KM; Myia, YZA; Jia, CP; Sihombing, H.; Sapuan, SM; Badarulzaman, NA

2017-10-01

This research was carried out to develop a reinforcing structure from recycled HDPE plastic lubricant containers to be embedded in concrete structure. Different forms and shapes of recycled HDPE plastic are designed as reinforcement incorporate with cement. In this study, the reinforcing structure was prepared by washing, cutting, dimensioning and joining of the waste HDPE containers (direct technique without treatment on plastic surface). Then, the rHDPE reinforced concrete was produced by casting based on standard of procedure in civil engineering technique. Eight different shapes of rHDPE in concrete structure were used to determine the concrete’s ability in terms of flexural strength. Embedded round shape in solid and perforated of rHDPE in concrete system drastically improved flexural strength at 17.78 % and 13.79 %. The result would seem that the concrete with reinforcing rHDPE structure exhibits a more gradual or flexible properties than concrete beams without reinforcement that has the properties of fragile.

Effects of chemical contamination on HDPE - thermo-mechanical and characterisation properties

International Nuclear Information System (INIS)

Ashraf, G.

2002-01-01

Studying the effects of chemical contamination on HDPE is an important precursor in recycling of plastic packaging and polymer reprocessing. This research involves and discusses the results of an in-depth investigation into the effects of chemically contaminating, using various acids, commercial grade high density polyethylene (HDPE) used commonly in packaging applications. An extensive formulation study was conducted and it became obvious that in some cases degradation had occurred to HDPE when chemically contaminated with particular functional group types. The functional groups in contaminated HDPE were successfully identified. A variety of analytical techniques such as Fourier transform Infra-red spectroscopy, X-ray Florescence, x-ray photo electron spectroscopy could identify compounds such as HCl acid, HNO/sub 3/ acid and other related contaminants. Some chemical additives had effects on the mechanical and thermal properties when added in the most appropriate concentration. The results have shown lower tensile modulus and strength tensile elongation, lower modular weight, melt flow index and crystallinity. The amount of contaminant concentration, the type of chemical functional groups used and the type of test selected to affect degradation are important factors in proving the effects of chemical contamination on HDPE in the melt state. (author)

Pengaruh Penggunaan Serat High Density Polyethylene (Hdpe) Pada Campuran Beton Terhadap Kuat Tarik Beton

OpenAIRE

Rommel, Erwin; Rusdianto, Yunan; Kurniati, Anita

2014-01-01

Research on the addition of HDPE fibers in normal concrete is intended to determine therelationship between the percentage of variation of fiber addition of HDPE to the workability, tensilestrength and determine the pattern of deployment of fiber in concrete. The addition of HDPE fibersis intended to increase the tensile strength of concrete.The concrete was mixed using gresik cement type PPC, sand with the gradation limits zone 2,the gravel with a maximum grain size of 20 mm, and HDPE fibers...

Nanocompósitos poliméricos de polietileno de alta densidade contendo hidróxidos duplos lamelares intercalados com ânions derivados de corantes azo

Directory of Open Access Journals (Sweden)

Ademir Zimmermann

2014-06-01

Full Text Available O presente trabalho descreve a síntese e caracterização de hidróxidos duplos lamelares (HDL de Zn/Al na razão molar 2:1, os quais foram intercalados com íons cloreto hidratados e ânions derivados dos corantes azo alaranjado de metila (AM e alaranjado II (AII. Após caracterização, os materiais foram utilizados como cargas em polietileno de alta densidade (PEAD e nanocompósitos foram preparados por extrusão e injeção, seguindo a norma ASTM D638-10. Os teores de cargas variaram de 0,1 até 2% (incluindo-se os sais de sódio dos corantes e os nanocompósitos homogêneos foram avaliados em relação as suas propriedades estruturais, térmicas e mecânicas. De modo geral, após a adição das cargas existe somente uma pequena influência na temperatura de fusão e cristalização do PEAD. Para os HDLs contendo o pigmento intercalado com o ânion do corante AM e sais de sódio de ambos os corantes, as propriedades mecânicas apresentaram leve aumento do módulo e tensão de ruptura e diminuição do alongamento em relação ao polímero puro e um comportamento inverso foi observado para o ânion AII, além do HDL contendo ânions cloreto hidratados.

Effect of HDPE plastic waste towards batako properties

Science.gov (United States)

Nursyamsi, N.; Indrawan, I.; Theresa, V.

2018-02-01

Indonesia is the world’s second largest producer of plastic waste to the sea, after China. Most of the plastic waste is polyethylene. Polyethylene is a polymer consisting of long chains of ethylene monomers. Moreover, polyethylene is plastic that has characteristics such as; thermoplastic, elastic, non-translucent, odorless, slightly opaque and transparent, resistant to impact and has a resistance of up to 135 degrees Celsius. The type of HDPE plastic (high-density polyethylene), which has been cleaned and chopped as a substitute of fine aggregate, is used in the brick’s making process. HDPE has a stronger, harder, smoother and more resistant to high-temperature properties. In this study, a weight variation of 0%, 10%, and 20% of HDPE plastic wastes was used from the total weight of sand as a substitution. Furthermore, the tensile and compressive strength were tested on day 7. Based on the research, the quality of the specimen achieved was categorized in quality III according to SNI 03-0349-1989.

Efeito dos solventes orgânicos sobre o comportamento físico-químico do polietileno de alta densidade (PEAD e polipropileno (PP

Directory of Open Access Journals (Sweden)

Thieres Magaive Costa Pereira

2014-06-01

Full Text Available O mercado brasileiro de embalagens empregado ao armazenamento de petróleo e seus derivados vem crescendo a cada ano, sendo constituídas basicamente por polietileno de alta densidade (PEAD e polipropileno (PP. Contudo durante o armazenamento, a matriz polimérica fica exposta ao óleo, comprometendo suas propriedades físicas e consequentemente a durabilidade do material. Portanto, estudos relacionados com a interação entre solventes orgânicos e a matriz polimérica tornam-se importantes. Neste trabalho, a interação do PEAD e PP com diferentes solventes apolares (tolueno, n-heptano, n-decano e n-tetradecano foram estudadas em função da temperatura (25, 50 e 80 ºC. Os valores de ganho de massa, coeficientes de difusão, sorção, permeabilidade e parâmetros de mecanismo de transporte foram calculados. O ganho de massa observado para o PP foi maior do que para o PEAD, em todas as temperaturas, sendo que o tolueno foi o solvente responsável pelo maior ganho de massa, atingindo o equilíbrio em um menor intervalo de tempo. Esse resultado corrobora com os valores de coeficiente de difusão e de permeabilidade, que aumentaram na seguinte ordem: n-heptano > n-decano > n-tetradecano. Uma ordem inversa foi observada para os solventes alifáticos quando os valores de coeficiente de sorção foram calculados. O mecanismo de transporte foi também estudado através da regressão dos dados de sorção, sendo classificado como anômalo.

Enhanced Thermal, Mechanical and Morphological Properties of CNT/HDPE Nanocomposite Using MMT as Secondary Filler

OpenAIRE

M. E. Ali Mohsin; Agus Arsad; Othman Y. Alothman

2014-01-01

This study explains the influence of secondary filler on the dispersion of carbon nanotube (CNT) reinforced high density polyethylene (HDPE) nanocomposites (CNT/HDPE). In order to understand the mixed-fillers system, Montmorillonite (MMT) was added to CNT/HDPE nanocomposites. It was followed by investigating their effect on the thermal, mechanical and morphological properties of the aforesaid nanocomposite. Incorporation of 3 wt% each of MMT into CNT/HDPE nanocomposite resulted to the increas...

Estrés abiótico en maíz : efectos sobre la variabilidad poblacional del crecimiento de las plantas, la partición de biomasa y el desarrollo reproductivo en genotipos contrastantes en su tolerancia a la densidad

OpenAIRE

Rossini, María de los Angeles

2012-01-01

Los sistemas de producción de maíz (Zea mays L.)en secano con altas densidades de siembra promueven procesos de competencia intra-específica desde etapas tempranas del desarrollo. Existen diferencias genotípicas en la evolución temporal de la variabilidad poblacional del crecimiento de las plantas (indicativa de la intensidad de la competencia intra-específica)en cultivos con densidades de siembra contrastantes. Sin embargo, esta información es escasa en cultivos bajo estrés hídrico y nitroge...

Nanoheteroestructuras de GaAs/AlGaAs. Simulación y aplicación en transistores de alta movilidad

Directory of Open Access Journals (Sweden)

Eduardo Martín Rodríguez

2011-01-01

Los transistores de alta movilidad (HEMT, High Electron Mobility Transistor son una de las aplicaciones más importantes de las propiedades de las heteroestructuras, con frecuencias de trabajo en el rango de 30 a 300 GHz. La simulación de un ejemplo de estos transistores es presentada en este trabajo, lográndose una densidad de corriente máxima en el canal de 1 A/mm2 comparable con resultados reportados para transistores similares.

Changes in mechanical properties due to gamma irradiation of high-density polyethylene (HDPE

Directory of Open Access Journals (Sweden)

S. S. Cota

2007-06-01

Full Text Available This paper presents an experimental analysis of the effect of dose and dose rate parameters during gamma irradiation of high-density polyethylene (HDPE samples. Considerations concerning the influence of these parameters on HDPE mechanical strength properties as a result of the predominance of oxidative degradation or of cross-linking are presented. The experimental results show an improvement of HDPE mechanical strength as dose increases, indicating the predominance of cross-linking over oxidative degradation and that lower doses are necessary to obtain a similar change in resistance parameters when radiation is applied at lower dose rates, showing that gamma radiation affects the HDPE in a more efficient way at lower dose rates.

Changes in mechanical properties due to gamma irradiation of high-density polyethylene (HDPE)

International Nuclear Information System (INIS)

Cota, S.S.; Vasconcelos, V.; Senne Junior, M.; Carvalho, L.L.; Rezende, D.B.; Correa, R.F.

2007-01-01

This paper presents an experimental analysis of the effect of dose and dose rate parameters during gamma irradiation of high-density polyethylene (HDPE) samples. Considerations concerning the influence of these parameters on HDPE mechanical strength properties as a result of the predominance of oxidative degradation or of cross-linking are presented. The experimental results show an improvement of HDPE mechanical strength as dose increases, indicating the predominance of cross-linking over oxidative degradation and that lower doses are necessary to obtain a similar change in resistance parameters when radiation is applied at lower dose rates, showing that gamma radiation affects the HDPE in a more efficient way at lower dose rates. (author)

Effect of compatibilizer on impact and morphological analysis of recycled HDPE/PET blends

Energy Technology Data Exchange (ETDEWEB)

Salleh, Mohd Nazry [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia and School of Materials Engineering, Universiti Malaysia Perlis, 02600 Jejawi, Perlis (Malaysia); Ahmad, Sahrim; Ghani, Mohd Hafizuddin Ab; Chen, Ruey Shan [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia)

2013-11-27

Blends based on recycled high density polyethylene (rHDPE) and recycled polyethylene terephthalate (rPET) were prepared using a corotating twin screw extruder. PET and HDPE are incompatible polymers and their blends showed poor properties. Compatibilization is a step to obtain blends with good mechanical properties and in this work, ethylene glycidyl methacrylate copolymer (E-GMA) was used as a compatibilizing agent. The effect of blends based on rHDPE and rPET with and without a compatibilizer, E-GMA were examined. From the studies clearly showed that the addition of 5% E-GMA increased the impact strength. SEM analysis of rHDPE/rPET blends confirmed the morphological interaction and improved interfacial bonding between two phases.

Surface Spectroscopic Signatures of Mechanical Deformation in HDPE.

Science.gov (United States)

Averett, Shawn C; Stanley, Steven K; Hanson, Joshua J; Smith, Stacey J; Patterson, James E

2018-01-01

High-density polyethylene (HDPE) has been extensively studied, both as a model for semi-crystalline polymers and because of its own industrial utility. During cold drawing, crystalline regions of HDPE are known to break up and align with the direction of tensile load. Structural changes due to deformation should also manifest at the surface of the polymer, but until now, a detailed molecular understanding of how the surface responds to mechanical deformation has been lacking. This work establishes a precedent for using vibrational sum-frequency generation (VSFG) spectroscopy to investigate changes in the molecular-level structure of the surface of HDPE after cold drawing. X-ray diffraction (XRD) was used to confirm that the observed surface behavior corresponds to the expected bulk response. Before tensile loading, the VSFG spectra indicate that there is significant variability in the surface structure and tilt of the methylene groups away from the surface normal. After deformation, the VSFG spectroscopic signatures are notably different. These changes suggest that hydrocarbon chains at the surface of visibly necked HDPE are aligned with the direction of loading, while the associated methylene groups are oriented with the local C 2 v symmetry axis roughly parallel to the surface normal. Small amounts of unaltered material are also found at the surface of necked HDPE, with the relative amount of unaltered material decreasing as the amount of deformation increases. Aspects of the nonresonant SFG response in the transition zone between necked and undeformed polymer provide additional insight into the deformation process and may provide the first indication of mechanical deformation. Nonlinear surface spectroscopy can thus be used as a noninvasive and nondestructive tool to probe the stress history of a HPDE sample in situations where X-ray techniques are not available or not applicable. Vibrational sum-frequency generation thus has great potential as a platform for

Modeling benzene permeation through drinking water high density polyethylene (HDPE) pipes.

Science.gov (United States)

Mao, Feng; Ong, Say Kee; Gaunt, James A

2015-09-01

Organic compounds such as benzene, toluene, ethyl benzene and o-, m-, and p-xylene from contaminated soil and groundwater may permeate through thermoplastic pipes which are used for the conveyance of drinking water in water distribution systems. In this study, permeation parameters of benzene in 25 mm (1 inch) standard inside dimension ratio (SIDR) 9 high density polyethylene (HDPE) pipes were estimated by fitting the measured data to a permeation model based on a combination of equilibrium partitioning and Fick's diffusion. For bulk concentrations between 6.0 and 67.5 mg/L in soil pore water, the concentration-dependent diffusion coefficients of benzene were found to range from 2.0×10(-9) to 2.8×10(-9) cm2/s while the solubility coefficient was determined to be 23.7. The simulated permeation curves of benzene for SIDR 9 and SIDR 7 series of HDPE pipes indicated that small diameter pipes were more vulnerable to permeation of benzene than large diameter pipes, and the breakthrough of benzene into the HDPE pipe was retarded and the corresponding permeation flux decreased with an increase of the pipe thickness. HDPE pipes exposed to an instantaneous plume exhibited distinguishable permeation characteristics from those exposed to a continuous source with a constant input. The properties of aquifer such as dispersion coefficients (DL) also influenced the permeation behavior of benzene through HDPE pipes.

Melting and crystallization behavior of partially miscible high density polyethylene/ethylene vinyl acetate copolymer (HDPE/EVA) blends

Energy Technology Data Exchange (ETDEWEB)

Chen, Yang; Zou, Huawei, E-mail: hwzou@163.com; Liang, Mei, E-mail: liangmeiww@163.com; Cao, Ya

2014-06-01

Highlights: • HDPE/EVA blends undergo phase separation, making it an interesting topic to investigate the relationships between miscibility and crystallization. • Influences from blending on the crystallization kinetics were successfully evaluated by Friedman's and Khanna's method. • X-ray diffraction studies revealed that blending with EVA the unit length of the unit cell of the HDPE increases. • Thermal fractionation method was successfully used to characterize the co-crystallization in HDPE/EVA blends. - Abstract: Crystallization studies on HDPE/EVA blends and the individual components were performed with differential scanning calorimetry (DSC) technique and wide angle X-ray scattering (WAXS). Influences of blending on the crystallization kinetics of each component in HDPE/EVA mixture were evaluated by Friedman's activation energy and Khanna's crystallization rate coefficient (CRC). The addition of more HDPE into the EVA matrix causes more heterogeneous nucleation while the addition of EVA would hinder the nucleation of HDPE at the beginning of cooling process. Inter-molecular interaction in the melt facilitated the crystallization of both EVA and HDPE components. X-ray diffraction studies revealed that HDPE and EVA have orthorhombic unit cell. Blending with EVA did not affect the crystalline structure of HDPE. In addition, a little shift of (1 1 0), (2 0 0) and (0 2 0) crystalline peaks toward lower 2θ values of samples indicating a little increase of unit cell parameters of the orthorhombic unit cell of polyethylene. Thermal fractionation results showed that co-crystallization took place in the HDPE/EVA blend. All those results indicated that the polymer pair we choose was partially miscible.

Contribution of Brazil nut shell fiber and electron-beam irradiation in thermomechanical properties of HDPE

International Nuclear Information System (INIS)

Polato, Pamella; Lorusso, Leandro Alex; Souza, Clecia de Moura; Moura, Esperidiana Augusta Barretos de; Chinellato, Anne; Rosa, Ricardo de

2010-01-01

In the present work, the influence of electron-beam irradiation on thermo-mechanical properties of HDPE and HDPE/Brazil nut shell fiber composite was investigated. The materials were irradiated at radiation dose 50 kGy using a 1.5 MeV electron beam accelerator, at room temperature in presence of air. The irradiated and non-irradiated samples were submitted to thermo-mechanical tests and the correlation between their properties was discussed. The results showed that the incorporation of Brazil nut shell fiber represented a significant gain (p < 0,05) in tensile strength at break, flexural strength, flexural module, Vicat softening temperature and heat distortion temperature (HDT) properties of the HDPE. In addition, the irradiated HDPE/Brazil nut shell fiber composite presented a significant increase (p < 0.05) in this properties compared with irradiated HDPE. (author)

Collagen-grafted porous HDPE/PEAA scaffolds for bone reconstruction.

Science.gov (United States)

Kim, Chang-Shik; Jung, Kyung-Hye; Kim, Hun; Kim, Chan-Bong; Kang, Inn-Kyu

2016-01-01

After tumor resection, bone reconstruction such as skull base reconstruction using interconnected porous structure is absolutely necessary. In this study, porous scaffolds for bone reconstruction were prepared using heat-pressing and salt-leaching methods. High-density polyethylene (HDPE) and poly(ethylene-co-acrylic acid) (PEAA) were chosen as the polymer composites for producing a porous scaffold of high mechanical strength and having high reactivity with biomaterials such as collagen, respectively. The porous structure was observed through surface images, and its intrusion volume and porosity were measured. Owing to the carboxylic acids on PEAA, collagen was successfully grafted onto the porous HDPE/PEAA scaffold, which was confirmed by FT-IR spectroscopy and electron spectroscopy for chemical analysis. Osteoblasts were cultured on the collagen-grafted porous scaffold, and their adhesion, proliferation, and differentiation were investigated. The high viability and growth of the osteoblasts suggest that the collagen-grafted porous HDPE/PEAA is a promising scaffold material for bone generation.

Biodegradation of HDPE by Aspergillus spp. from marine ecosystem of Gulf of Mannar, India.

Science.gov (United States)

Sangeetha Devi, Rajendran; Rajesh Kannan, Velu; Nivas, Duraisamy; Kannan, Kanthaiah; Chandru, Sekar; Robert Antony, Arokiaswamy

2015-07-15

High density polyethylene (HDPE) is the most commonly found non-degradable solid waste among the polyethylene. In this present study, HDPE degrading various fungal strains were isolated from the polyethylene waste dumped marine coastal area and screened under in vitro condition. Based on weight loss and FT-IR Spectrophotometric analysis, two fungal strains designated as VRKPT1 and VRKPT2 were found to be efficient in HDPE degradation. Through the sequence analysis of ITS region homology, the isolated fungi were identified as Aspergillus tubingensis VRKPT1 and Aspergillus flavus VRKPT2. The biofilm formation observed under epifluorescent microscope had shown the viability of fungal strains even after one month of incubation. The biodegradation of HDPE film nature was further investigated through SEM analysis. HDPE poses severe environmental threats and hence the ability of fungal isolates was proved to utilize virgin polyethylene as the carbon source without any pre-treatment and pro-oxidant additives. Copyright © 2015 Elsevier Ltd. All rights reserved.

Isothermal Crystallization Kinetics of HDPE/HA Compounds Irradiated with Sterilization Doses of Gamma Rays

International Nuclear Information System (INIS)

Albano, C.

2006-01-01

The objective of this work was to study the isothermal crystallization of High Density Polyethylene/Hydroxyapatite nanocomposites, with 2 and 5 ppc of HA, irradiated with 25 kGy (sterilization dose) of γ-Ray from a 60 C o source, at a rate of 4.8 kGy/h in air and at room temperature. The selected crystallization temperatures were 118, 117, 116 and 115 degree. The crystallization kinetics was analyzed using the Avrami's model whose parameters were optimized using a non-linear regression technique. Regression results show that the Avrami exponent varies between 1.8 and 1.5, meaning that the spherulitic growth is mainly two dimensional. Values for specific crystallization constant 'k' were found to be higher for HDPE/HA compounds than for pure HDPE, clearly indicating the presence of an HA nucleation effect. It was also observed that values for the specific crystallization constant 'k' decreases with increasing temperatures, being this effect more noticeable for HDPE/HA compounds than for pure HDPE. Regarding to irradiated samples, their 'k' values were found to be lower than those for non irradiated samples, the difference getting more significant with decreasing crystallization temperature. Simulation of experimental data with the Avrami's model show a clear influence of the crystallization temperature, the HA content in the sample and the amount of applied radiation. It was also observed that the Avrami model correlates satisfactorily experimental data for not irradiated samples of pure HDPE and HDPE/HA compounds at the highest crystallization (T c ). However, as the crystallization temperature decreases, the values simulated with the Avrami model increasingly deviate from experimental data, specifically at the highest values of the relative crystallinity. This effect is even stronger on irradiated samples of HDPE and HDPE/HA compounds

Study of positron annihilation lifetime spectroscopy in carbon black-filled HDPE composite

CERN Document Server

Zhang Xian Feng; Zhou Xian Yi; Weng Hu Imin; Ye Bang Jiao; Han Rong Dian; Jia Shao Jin; Zhang Zhi Cheng

2002-01-01

The variation of the electrical conductivity of high density polyethylene (HDPE) with the carbon black (CB) content was studied using positron annihilation lifetime spectroscopy (PALS) and free-volume model, the crystallinity of HDPE/CB composite and 'percolation' effect were discussed with measurements of conductivity and DSC test

Efecto de la densidad de explantes y el volumen de medio de cultivo sobre la multiplicación in vitro de arándano (Vaccinium corymbosum L. variedades Brigitta y Legacy

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Mario Rodríguez Beraud

2015-01-01

Full Text Available El objetivo fue evaluar la multiplicación in vitro de dos variedades de arándano (Vaccinium corymbosum L., “Brigitta” y “Legacy”, en respuesta a cinco densidades de explantes (5, 10, 15, 20 y 25 y cuatro volúmenes de medio (10, 20, 30 y 40 mL utilizando para ambas variedades el medio WPM (Woody Plant Medium en un diseño completamente al azar con 20 tratamientos y 12 repeticiones por tratamiento. Transcurrido 45 días se evaluó: altura de brote, número de brotes/explante, número de nudos/brote y número de brotes/frasco. Brigitta obtuvo la mayor altura del brote en tratamientos con densidades y volúmenes elevados, mientras que Legacy obtuvo el mayor promedio de altura del brote con densidades intermedias y volúmenes elevados. En cuanto al número de brotes/explante, el volumen de medio no influyó en la variedad Brigitta, en cambio, altas densidades la afectaron significativamente, mientras que en Legacy el máximo número de brotes se alcanzó con densidades bajas y volúmenes intermedios. En relación al número de nudos por explante Brigitta obtuvo los valores más bajos comparados con Legacy, pero en ambas variedades se produjo una disminución del número de nudos con menores volúmenes de medio. Para el número de brotes por frasco Brigitta obtuvo las mayores respuestas con densidades elevadas, superando los 40 brotes por frasco. En cambio, en Legacy el resultado máximo se obtuvo con la densidad 25 explantes en 30 mL de medio. Por lo tanto, se concluye que ambas variedades fueron influenciadas tanto por el volumen del medio como la densidad de explantes.

Characterization by EPR of radicals in HDPE, PA6 and HDPE/PA6 blend irradiated with gamma rays

Energy Technology Data Exchange (ETDEWEB)

Silva, P. [Centro de Fisica, Instituto Venezolano de Investigacion Cientifica IVIC, Carretera Panamericana Km. 11, A.P. 21827, Caracas 1020-A (Venezuela); Albano, C.; Lovera, D. [Centro de Quimica, IVIC (Venezuela); Perera, R. [Departamento de Mecanica, Universidad Simon Bolivar, Caracas (Venezuela)

2003-07-01

Using electron paramagnetic resonance (EPR), we studied the tree radical formation in high-density Polyethylene (HDPE), polyamide (PA6) and HDPE/PA6 (80/20)blend, irradiated with integral doses (D), 0 < D < 1000 KGy, with a dose rate of irradiation in air of 6.6 KGy/h. Typical spectra indicative of the formation of allyl, alkyl and poly enyl radicals were obtained. A decay in the total number of spins per gram (C/g), when the samples are aged by a period of time of 30 days, was found, which is typical of a recombination of radicals with their environment. Additionally, a different order fit for the C/g as a function of D was obtained, which is indicative of the complex behavior of the kinetics of the decomposition. (Author)

Effect of admixed high-density polyethylene (HDPE) spheres on contraction stress and properties of experimental composites.

Science.gov (United States)

Ferracane, J L; Ferracane, L L; Braga, R R

2003-07-15

Additives that provide stress relief may be incorporated into dental composites to reduce contraction stress (CS). This study attempted to test the hypothesis that conventional fillers could be replaced by high-density polyethylene (HDPE) spheres in hybrid and nanofill composites to reduce CS, but with minimal effect on mechanical properties. Nanofill and hybrid composites were made from a Bis-GMA/TEGDMA resin having either all silica nanofiller or 75 wt.% strontium glass + 5 wt.% silica and replacing some of the nanofiller or the glass with 0%, 5% (hybrid only), 10% or 20 wt.% HDPE. The surface of the HDPE was either left untreated or had a reactive gas surface treatment (RGST). Contraction stress (CS) was monitored for 10 min in a tensilometer (n = 5) after light curing for 60 s at 390 mW/cm(2). Other specimens (n = 5) were light cured 40 s from two sides in a light-curing unit and aged 1 d in water before testing fracture toughness (K(Ic)), flexure strength (FS), and modulus (E). Results were analyzed by ANOVA with Tukey's multiple comparison test at p HDPE except for FS-10% HDPE hybrid (RGST higher). An increased level of HDPE reduced contraction stress for both types of composites. Flexure strength, modulus (hybrid only), and fracture toughness were also reduced as the concentration of HDPE increased. SEM showed evidence for HDPE debonding and plastic deformation during fracture of the hybrid composites. In conclusion, the addition of HDPE spheres reduces contraction stress in composites, either through stress relief or a reduction in elastic modulus. Copyright 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 66B: 318-323, 2003

Effects of Cross-Linking on the Hydrostatic Pressure Testing for HDPE Pipe Material using Electron Beam Machine

International Nuclear Information System (INIS)

Mohd Jamil Bin Hashim

2011-01-01

One of the most inventive, sustainable strategies used in engineering field is to improve the quality of material and minimize production cost of material for example in this paper is HDPE material. This is because HDPE is an oil base material. This paper proposes to improve its hydrostatic pressure performance for HDPE pipe. The burst test is the most direct measurement of a pipe materials resistance to hydrostatic pressure. Test will be conducted in accordance with ASTM standard for HDPE pipe that undergo electron beam irradiation cross-linking. Studies show the effect of electron beam irradiation will improve the mechanical properties of HDPE pipe. When cross-linking is induced, the mechanical properties such as tensile strength and young modulus is increase correspond to the radiation dose. This happen because the structure of HDPE, which is thermoplastic change to thermosetting. This will indicate the variability of irradiation dose which regard to the pipe pressure rating. Hence, the thickness ratio of pipe will be re-examining in order to make the production of HDPE pipe become more economical. This research review the effects of electron beam on HDPE pipe, as well as to reduce the cost of its production to improve key properties of selected plastic pipe products. (author)

Densidad y estructura poblacional de Cebus capucinus curtus (Primates: Cebidae y Bradypus variegatus gorgon (Pilosa: Bradypodidae, en Isla Gorgona , Colombia

Directory of Open Access Journals (Sweden)

Mario Fernando Garcés-Restrepo

2014-02-01

Full Text Available En Isla Gorgona se registran dos subespecies endémicas de mamíferos arbóreos, el Mono capuchino de pecho blanco (Cebus capucinus curtus y el Perezoso de tres dedos de garganta marrón (Bradypus variegatus gorgon, especies importante para la conservación debido a su carácter endémico y papel ecológico como dispersores de semillas en el PNN Gorgona. En este trabajo se presenta información sobre la ecología poblacional de estas dos subespecies, utilizando el método de muestreo por distancia con transectos lineales para establecer la densidad, además se describió la estructura etaria general de cada población con base en los muestreos y observaciones directas. La densidad de C. capucinus curtus en isla Gorgona fue de 170,6 ind/km² (IC 95%=122,0-238,4 ind/km² mientras que para B. variegatus gorgon fue de 2,6 ind/km² (IC 95%=1,3-4,9 ind/km². El registro de densidad de C. capucinus curtus en isla Gorgona es el más alto para la especie en todo su rango de distribución geográfica, mientras que el de B. variegatus gorgon es el más bajo reportado para la especie. La alta densidad de C. capucinus curtus estaría relacionada con un efecto sinérgico entre la baja depredación natural y la continua disponibilidad de alimento, mientras que la baja densidad de B. variegatus gorgon estaría relacionada con la presión de caza realizada en el pasado, la baja tasa reproductiva de la especie y una pandemia ocurrida en el año 2005. Se recomienda el monitoreo constante de las poblaciones y estudios de salud poblacional para B. variegatus gorgon.

Effect of Addition of Soybean Oil and Gamma-Ray Cross-linking on the Nanoporous HDPE Membrane

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Jong-Seok Park

2012-01-01

Full Text Available A nanoporous high-density polyethylene (HDPE membrane was prepared by a wet process. Soybean oil and dibutyl phthalate (DBP were premixed as codiluents, and gamma-rays were used for the cross-linking of HDPE. The pore volume of the nanoporous HDPE membranes with soybean oil was affected by the extracted amount of oil. The tensile strength of the membrane improved with an increasing absorbed dose up to 60 kGy, but decreased at 80 kGy due to severe degradation. The ionic conductivity of the nanoporous HDPE membrane did not really change with an increasing absorbed dose because the pores had already been formed before the gamma-ray radiation. Finally, the electrochemical stability of the HDPE membrane increased when the absorbed dose increased up to 60 kGy.

Volatile organic components migrating from plastic pipes (HDPE, PEX and PVC) into drinking water.

Science.gov (United States)

Skjevrak, Ingun; Due, Anne; Gjerstad, Karl Olav; Herikstad, Hallgeir

2003-04-01

High-density polyethylene pipes (HDPE), crossbonded polyethylene pipes (PEX) and polyvinyl chloride (PVC) pipes for drinking water were tested with respect to migration of volatile organic components (VOC) to water. The odour of water in contact with plastic pipes was assessed according to the quantitative threshold odour number (TON) concept. A major migrating component from HDPE pipes was 2,4-di-tert-butyl-phenol (2,4-DTBP) which is a known degradation product from antioxidants such as Irgafos 168(R). In addition, a range of esters, aldehydes, ketones, aromatic hydrocarbons and terpenoids were identified as migration products from HDPE pipes. Water in contact with HDPE pipes was assessed with respect to TON, and values > or =4 were determined for five out of seven brands of HDPE pipes. The total amount of VOC released to water during three successive test periods were fairly constant for the HDPE pipes. Corresponding migration tests carried out for PEX pipes showed that VOC migrated in significant amounts into the test water, and TON >/=5 of the test water were observed in all tests. Several of the migrated VOC were not identified. Oxygenates predominated the identified VOC in the test water from PEX pipes. Migration tests of PVC pipes revealed few volatile migrants in the test samples and no significant odour of the test water.

Efecto de abono orgánico y densidad de siembra en crecimiento y producción de papa china (Colocasia esculenta L.

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Nilsen Leonardo Lasso-Rivas

2016-06-01

Full Text Available La papa china es un cultivo importante para los habitantes de la región Pacífica colombiana, este cultivo posee una dinámica de producción fluctuante con rendimientos promedio por debajo de su potencial. En este trabajo se evaluó el efecto de la aplicación de abono orgánico (gallinaza y la densidad de siembra en el crecimiento y la producción de papa china en la vereda Zacarías, Buenaventura, Valle del Cauca, Colombia. El diseño experimental consistió en un arreglo de bloques completamente al azar con un arreglo de parcelas divididas, con tres densidades de siembra (100 cm x 50 cm, 60 cm x 60 cm, y 50 cm x 40cm y tres niveles de fertilización orgánica (alta 3 kg planta-1, media 2 kg planta-1, y baja 1 kg planta-1. Los resultados mostraron que la distancia de siembra es el factor que afecta de manera significativa las variables de desarrollo inicial de las plantas (altura de la planta, número de hojas y circunferencia del tallo. Para las variables de producción (longitud, circunferencia y peso del cormo se encontró que con la distancia de siembra de 100 cm x 50 cm se obtuvo el mejor desarrollo de producción de cormos, y la dosis de fertilización alta resultó en mejor desarrollo en la producción en las plantas.

HDPE-Al2O3-HAp composites for biomedical applications: processing and characterizations.

Science.gov (United States)

Nath, Shekhar; Bodhak, Subhadip; Basu, Bikramjit

2009-01-01

The objective of this work is to demonstrate how the stiffness, hardness, as well as the biocompatibility property, of bioinert high-density polyethylene (HDPE) can be significantly improved by the combined addition of both bioinert and bioactive ceramic fillers. For this purpose, different volume fractions of hydroxyapatite and alumina, limited to a total of 40 vol %, have been incorporated in HDPE matrix. All the hybrid composites and monolithic HDPE were developed under optimized hot pressing condition (130 degrees C, 0.5 h, 92 MPa pressure). The results of the mechanical property characterization reveal that higher elastic modulus (6.2 GPa) and improved hardness (226.5 MPa) could be obtained in the developed HDPE-20 vol %-HAp-20 vol % Al(2)O(3) composite. Under the selected fretting conditions against various counterbody materials (steel, Al(2)O(3), and ZrO(2)), an extremely low COF of (0.07-0.11) and higher wear resistance (order of 10(-6) mm(3)/Nm) are obtained with the HDPE/20 vol % HAp/20 vol % Al(2)O(3) composite in both air and simulated body fluid environment. Importantly, in-vitro cell culture study using L929 fibroblast cells confirms favorable cell adhesion properties in the developed hybrid composite. (c) 2008 Wiley Periodicals, Inc.

The effect of partially stabilized zirconia on the biological properties of HA/HDPE composites in vitro.

Science.gov (United States)

Sadi, A Yari; Shokrgozar, M A; Homaeigohar, S Sh; Hosseinalipour, M; Khavandi, A; Javadpour, J

2006-05-01

The effect of partially stabilized zirconia (PSZ) on the biological properties of the hyroxyapatite - high density polyethylene (HA/HDPE) composites was studied by investigating the simultaneous effect of hydroxyapatite and PSZ volume fractions on the in vitro response of human osteoblast cells. The biocompatibility of composite samples with different volume fraction of HA and PSZ powders was assessed by proliferation, alkaline phosphatase (ALP) and cell attachment assays on the osteoblast cell line (G-292) in different time periods. The effect of composites on the behavior of G-292 cells was compared with those of HDPE and TPS (Tissue Culture Poly Styrene as negative control) samples. Results showed a higher proliferation rate of G-292 cells in the presence of composite samples as compared to the HDPE sample after 7 and 14 days of incubation period. ALP production rate in all composite samples was higher than HDPE and TPS samples. The number of adhered cells on the composite samples was higher than the number adhered on the HDPE and TPS samples after the above mentioned incubation periods. These findings indicates that the addition of PSZ does not have any adverse affect on the biocompatibility of HA/HDPE composites. In fact in some experiments PSZ added HA/HDPE composites performed better in proliferation, differentiation and attachment of osteoblastic cells.

Interfacial thermal resistance between high-density polyethylene (HDPE) and sapphire

International Nuclear Information System (INIS)

Zheng Kun; Ma Yong-Mei; Wang Fo-Song; Zhu Jie; Tang Da-Wei

2014-01-01

To improve the thermal conductivity of polymeric composites, the numerous interfacial thermal resistance (ITR) inside is usually considered as a bottle neck, but the direct measurement of the ITR is hardly reported. In this paper, a sandwich structure which consists of transducer/high density polyethylene (HDPE)/sapphire is prepared to study the interface characteristics. Then, the ITRs between HDPE and sapphire of two samples with different HDPE thickness values are measured by time-domain thermoreflectance (TDTR) method and the results are ∼ 2 × 10 −7 m 2 ·K·W −1 . Furthermore, a model is used to evaluate the importance of ITR for the thermal conductivity of composites. The model's analysis indicates that reducing the ITR is an effective way of improving the thermal conductivity of composites. These results will provide valuable guidance for the design and manufacture of polymer-based thermally conductive materials. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Facile fabrication of HDPE-g-MA/nanodiamond nanocomposites via one-step reactive blending.

Science.gov (United States)

Song, Ping'an; Yu, Youming; Wu, Qiang; Fu, Shenyuan

2012-06-29

In this letter, nanocomposites based on maleic anhydride grafted high density polyethylene (HDPE-g-MA) and amine-functionalized nanodiamond (ND) were fabricated via one-step reactive melt-blending, generating a homogeneous dispersion of ND, as evidenced by transmission electron microscope observations. Thermal analysis results suggest that addition of ND does not affect significantly thermal stability of polymer matrix in nitrogen. However, it was interestingly found that incorporating pure ND decreases the thermal oxidation degradation stability temperature, but blending amino-functionalized ND via reactive processing significantly enhances it of HDPE in air condition. Most importantly, cone tests revealed that both ND additives and reactive blending greatly reduce the heat release rate of HDPE. The results suggest that ND has a potential application as flame retardant alternative for polymers. Tensile results show that adding ND considerably enhances Young's modulus, and reactive blending leads to further improvement in Young's modulus while hardly reducing the elongation at break of HDPE.

Blends of HDPE wastes: study of the properties.

Science.gov (United States)

Sánchez-Soto, M; Rossa, A; Sánchez, A J; Gámez-Pérez, J

2008-12-01

In this work we have analysed the properties of blends of recycled high-density polyethylene (HDPE) filled with talc. We have used two kinds of polymer matrices. The first one came entirely from ground injection moulded parts whereas the second was bimodal, incorporating 80% of the previous HDPE and 20% of recycled HDPE coming from bottles. We have also used two kinds of commercial talc characterized by a medium particle size of 2 microm and 10 microm, respectively. The amount of talc added to both matrices weighed of 10% and 20%. With regards to the mechanical properties of the analysed composites, greater values of Young's modulus and break stresses were found using a smaller particle size and higher talc content. On the other hand, the combination of the two HDPEs with very different viscosities produced a notable increase in the strain at break and in the absorbed energy; both measured at high and low strain rates. Despite the differences in viscosities between the two HDPEs, we did not observe separation of phases during either the processing or testing. Under impact loading, the higher energy absorption in the composites was observed when the finest talc grade with a 10% content weight was added to the bimodal matrix.

Preparation and characterization of electron-beam treated HDPE composites reinforced with rice husk ash and Brazilian clay

Energy Technology Data Exchange (ETDEWEB)

Ortiz, A.V., E-mail: angelortiz@ipen.br [Nuclear and Energy Research Institute, IPEN-CNEN/SP Av. Prof. Lineu Prestes 2242, São Paulo, SP 05508-000 (Brazil); Teixeira, J.G.; Gomes, M.G.; Oliveira, R.R. [Nuclear and Energy Research Institute, IPEN-CNEN/SP Av. Prof. Lineu Prestes 2242, São Paulo, SP 05508-000 (Brazil); Díaz, F.R.V. [Metallurgical and Materials Engineering Department, Polytechnic School, University of São Paulo Av. Prof. Mello de Morais 2463, São Paulo, SP 05508-900 (Brazil); Moura, E.A.B. [Nuclear and Energy Research Institute, IPEN-CNEN/SP Av. Prof. Lineu Prestes 2242, São Paulo, SP 05508-000 (Brazil)

2014-08-15

Highlights: • We examine changes in HDPE properties when waste and clay are used as reinforcement. • The addition of only 3% of clay leads to important gains in HDPE properties. • The use of electron-beam contributes to greater improvements in material properties. • We observe 85% of cross-linking degree for the HDPE when treated with e-beam. - Abstract: This work evaluates the morphology, mechanical and thermo-mechanical properties of high density polyethylene (HDPE) composites. HDPE reinforced with rice husk ashes (80:20 wt%), HDPE reinforced with clay (97:3 wt%) and HDPE reinforced with both rice husk ashes and clay(77:20:3 wt%) were obtained. The Brazilian bentonite chocolate clay was used in this study. This Brazilian smectitic clay is commonly used to produce nanocomposites. The composites were produced by melting extrusion process and then irradiation was carried out in a 1.5 MeV electron-beam accelerator (room temperature, presence of air). Comparisons using the irradiated and non-irradiated neat polymer, and the irradiated and non-irradiated composites were made. The materials obtained were submitted to tensile, flexural and impact tests. Additionally HDT, SEM and XRD analyses were carried out along with the sol–gel analysis which aimed to assess the cross-linking degree of the irradiated materials. Results showed great improvement in most HDPE properties and a high cross-linking degree of 85% as a result of electron-beam irradiation of the material.

A novel wood flour-filled composite based on microfibrillar high-density polyethylene (HDPE)/Nylon-6 blends.

Science.gov (United States)

Liu, Hongzhi; Yao, Fei; Xu, Yanjun; Wu, Qinglin

2010-05-01

A novel wood flour (WF)-filled composite based on the microfibrillar high-density polyethylene (HDPE) and Nylon-6 co-blend, in which both in situ formed Nylon-6 microfibrils and WF acted as reinforcing elements, was successfully developed using a two-step extrusion method. At the 30wt.% WF loading level, WF-filled composite based on the microfibrillized HDPE/Nylon-6 blend exhibited higher strengths and moduli than the corresponding HDPE-based composite. The incorporation of WF reduced short-term creep response of HDPE matrix and the presence of Nylon-6 microfibrils further contributed to the creep reduction. Copyright 2009 Elsevier Ltd. All rights reserved.

Comparative biodegradation of HDPE and LDPE using an indigenously developed microbial consortium.

Science.gov (United States)

Satlewal, Alok; Soni, Ravindra; Zaidi, Mgh; Shouche, Yogesh; Goel, Reeta

2008-03-01

A variety of bacterial strains were isolated from waste disposal sites of Uttaranchal, India, and some from artificially developed soil beds containing maleic anhydride, glucose, and small pieces of polyethylene. Primary screening of isolates was done based on their ability to utilize high- and low-density polyethylenes (HDPE/LDPE) as a primary carbon source. Thereafter, a consortium was developed using potential strains. Furthermore, a biodegradation assay was carried out in 500-ml flasks containing minimal broth (250 ml) and HDPE/ LDPE at 5 mg/ml concentration. After incubation for two weeks, degraded samples were recovered through filtration and subsequent evaporation. Fourier transform infrared spectroscopy (FTIR) and simultaneous thermogravimetric-differential thermogravimetry-differential thermal analysis TG-DTG-DTA) were used to analyze these samples. Results showed that consortium-treated HDPE (considered to be more inert relative to LDPE) was degraded to a greater extent 22.41% weight loss) in comparison with LDPE (21.70% weight loss), whereas, in the case of untreated samples, weight loss was more for LDPE than HDPE (4.5% and 2.5%, respectively) at 400 degrees . Therefore, this study suggests that polyethylene could be degraded by utilizing microbial consortia in an eco-friendly manner.

Degradação de poliolefinas utilizando catalisadores zeolíticos Degradation of polyolefins using zeolitic catalysts

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Maria Letícia M. Valle

2004-03-01

Full Text Available Neste trabalho foi estudada a degradação de alguns dos principais constituintes dos rejeitos plásticos (polietileno de alta densidade (HDPE, polietileno de baixa densidade (LDPE e polipropileno (PP, empregando-se um catalisador exausto de unidades de craqueamento de fluidos (FCC e um catalisador zeolítico (ADZ3 sintetizado em laboratório. Utilizando técnicas de termogravimetria (TG-DTG e cromatografia gasosa (CG, foi possível avaliar os produtos gerados no craqueamento destas poliolefinas. Na degradação catalítica de poliolefinas com catalisadores zeolíticos, verificou-se a obtenção preferencial de gasolina, GLP e diesel, produtos importantes na matriz energética brasileira. O catalisador de FCC exausto foi mais seletivo para a produção de gasolina e GLP, enquanto que a produção de diesel foi mais favorecida com o catalisador ADZ3.In this work the degradation of some of the main plastics responsible for waste, viz. high density polyethylene (HDPE, low density polyethylene (LDPE and polypropylene (PP, was studied using a spent FCC catalyst (fluid cracking catalyst and a zeolitic catalyst (ADZ3 synthesized in laboratory. Using thermogravimetry (TG-DTG and gas chromatography (GC techniques, it was possible to evaluate the products from these polyolefins cracking. The catalytic degradation of polyolefins led to a preferential production of LPG, diesel and gasoline, which are important products of the Brazilian energetic matrix. The spent FCC catalyst was more selective for production of LPG and gasoline, whereas the diesel production was more favored with the ADZ3 catalyst.

Effect of EVA on thermal stability, flammability, mechanical properties of HDPE/EVA/Mg(OH)2 composites

Science.gov (United States)

Cao, R.; Deng, Z. L.; Ma, Y. H.; Chen, X. L.

2017-06-01

In this work, ethylene vinyl acetate (EVA) is introduced to improve the properties of high-density polyethylene (HDPE)/magnesium hydroxide (MH) composites. The thermal stability, flame retardancy and mechanical properties of HDPE/EVA/MH composites are investigated and discussed. With increasing content of EVA, the limiting oxygen index (LOI) of the composites increases. The thermal stability analysis shows that the initial decomposition temperature begins at a low temperature; however, the residues of the composites at 600°C increase when HDPE is replaced by small amounts of EVA. The early degradation absorbs heat, dilute oxygen and residue. During this process, it protects the matrix inside. Compared with the HDPE/MH and EVA/MH composites, the ternary HDPE/EVA/MH composites exhibit better flame retardancy by increasing the LOI values, and reducing the heat release rate (HRR) and total heat release (THR). With increasing content of EVA, the mechanical properties can also be improved, which is attributed to the good affinity between EVA and MH particles.

Fabrication and materials properties of high-density polyethylene (HDPE)/biphasic calcium phosphate (BCP) hybrid bone plates

International Nuclear Information System (INIS)

Jo, Sun Young; Youn, Min Ho; Lim, Youn Mook; Gwon, Hui Jeong; Park, Jong Seok; Nho, Young Chang

2010-01-01

Biphasic calcium phosphate-reinforced high-density polyethylene (BCP/HDPE) hybrid composite is a new orthopedic biomaterial, which was made to simulate a natural bone composition. Calcium phosphate systems and HDPE hybrid composites have been used in biomedical applications without any inflammatory response. Differences in natural bone of both materials have motivated the use of coupling agents to improve their interfacial interfacial interactions. The composites were prepared using medical grade BCP powder and granular polyethylene. This material was produced by replacing the mineral component and collagen soft tissue of the bone with BCP and HDPE, respectively. As expected, increased volume fraction of either reinforcement type over 0 ∼ 50 vol.% resulted in a increased Vickers hardness and Young's modulus. Thus, BCP particle-reinforced HDPE composites possessed improved material and mechanical properties. BCP particles-reinforced composites were anisotropic due to an alignment of the particles in the matrix during a processing. On the other hand, bending and tensile strength was dramatically changed in the matrix. To change the material and mechanical properties of HDPE/BCP composites, the process of a blending was used, and its effect on the microstructure and mechanical proprieties of HDPE/BCP composites were investigated by means of FT-IR/ATR spectroscopy, XRD, FE-SEM, Vickers Hardness Testing Machine, Universal Testing Machine, Mercury Porosimeter and Ultrasonic Flaw Detector at room temperature. For the evaluation of the cell viability and proliferation onto the external surface of HDPE/BCP hybrid plates with a HaCaT cell line, which is a multipotent cell line able to differentiate towards different phenotypes under the action of biological factors, has been evaluated with in vitro studies and quantified by colormetric assays. These findings indicate that the HDPE/BCP hybrid plates are biocompatible and non-toxic

Studies on the effects of EPDM, SR on PTC- of HDPE/CB before and after γ-radiation

International Nuclear Information System (INIS)

Jia Shaojin; Jiang Pingkai; Xiu Qihui; Wang Zongguang; Zhang Zhicheng

2004-01-01

High-density-polyethylene (HDPE), Si rubber (SR) and ethylene-density-polyethylene (EPDM) were used as the polymer matrices. A kinds of carbon blacks was used as the conductive filler. The positive temperature coefficient (PTC) intensity of the HDPE/CB, HDPE/EPDM/CB composites flow during extrusion to produced was tested before and after irradiation. Compared to that of HDPE/CB composites, the electrical reproducibility of the irradiated HDPE/EPDM/CB composites of is better. The effects of γ-rays irradiation were also estimated. The results showed that the reproductive of the PTC effect was related to the adhesion between the interface of the polymer matrices and CB particles. These PTC phenomena and their distinctive aspects were described. The explanations were given from the structural characteristics of the blends, CB particles distribution and motion of polymer segments. (authors)

On the Injection Molding Processing Parameters of HDPE-TiO₂ Nanocomposites.

Science.gov (United States)

Mourad, Abdel-Hamid I; Mozumder, Mohammad Sayem; Mairpady, Anusha; Pervez, Hifsa; Kannuri, Uma Maheshwara

2017-01-20

In recent years, the development and use of polymeric nanocomposites in creating advanced materials has expanded exponentially. A substantial amount of research has been done in order to design polymeric nanocomposites in a safe and efficient manner. In the present study, the impact of processing parameters, such as, barrel temperature, and residence time on the mechanical and thermal properties of high density polyethylene (HDPE)-TiO₂ nanocomposites were investigated. Additionally, scanning electron microscopy and X-ray diffraction spectroscopy were used to analyze the dispersion, location, and phase morphology of TiO₂ on the HDPE matrix. Mechanical tests revealed that tensile strength of the fabricated HDPE-TiO₂ nanocomposites ranged between 22.53 and 26.30 MPa, while the Young's modulus showed a consistent increase as the barrel temperature increased from 150 °C to 300 °C. Moreover, the thermal stability decreased as the barrel temperature increased.

Sintering Process and Mechanical Property of MWCNTs/HDPE Bulk Composite.

Science.gov (United States)

Ming-Wen, Wang; Tze-Chi, Hsu; Jie-Ren, Zheng

2009-08-01

Studies have proved that increasing polymer matrices by carbon nanotubes to form structural reinforcement and electrical conductivity have significantly improved mechanical and electrical properties at very low carbon nanotubes loading. In other words, increasing polymer matrices by carbon nanotubes to form structural reinforcement can reduce friction coefficient and enhance anti-wear property. However, producing traditional MWCNTs in polymeric materix is an extremely complicated process. Using melt-mixing process or in situ polymerization leads to better dispersion effect on composite materials. In this study, therefore, to simplify MWCNTs /HDPE composite process and increase dispersion, powder was used directly to replace pellet to mix and sinter with MWCNTs. The composite bulks with 0, 0.5, 1, 2 and 4% nanotube content by weight was analyzed under SEM to observe nanotubes dispersion. At this rate, a MWCNTs/HDPE composite bulk with uniformly dispersed MWCNTs was achieved, and through the wear bench (Pin-on-Disk), the wear experiment has accomplished. Accordingly, the result suggests the sintered MWCNTs/HDPE composites amplify the hardness and wear-resist property.

Evaluation on Compression Properties of Different Shape and Perforated rHDPE in Concrete Structures

Science.gov (United States)

Yuhazri, M. Y.; Hafiz, K. M.; Myia, Y. Z. A.; Jia, C. P.; Sihombing, H.; Sapuan, S. M.; Badarulzaman, N. A.

2017-10-01

The purpose of this study was to develop a concrete structure by incorporating waste HDPE plastic as the main reinforcement material and cement as the matrix via standard casting technique. There are eight different shapes of rHDPE reinforcing structure were used to investigate the compression properties of produced concrete composites. Experimental result shown that the highest shape in compressive strength of rHDPE reinforcing structure were the concrete with the addition of X-perforated beam (18.22 MPa), followed by X-beam (17.7 MPa), square perforated tube (17.54 MPa), round tube (17.42 MPa) and round perforated tube (16.69 MPa). In terms of their compressive behavior, the average concrete containing rHDPE reinforcement was successfully improved by 6 % of the mechanical characteristic compared to control concrete. It is shown that the addition of waste plastic as reinforcement structure can provide better compressive strength based on their shape and pattern respectively.

SYNTHESIS AND CHARACTERIZATION OF HDPE PLASTIC FILM FOR HERBICIDE CONTAINER USING FLY ASH CLASS F AS FILLER

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Yatim Lailun Ni’mah

2010-06-01

Full Text Available High Density Polyethylene (HDPE plastic plays an important role in various applications, for example, it can be used as a container (bottle. Petrokimia Kayaku Company, a branch of Petrokimia Company of Gresik, produces herbicides using HDPE plastic bottles as their container. Those plastic bottles undergo degradation (kempot for certain period of time. The aim of this research is to characterize and to synthesize the HDPE plastic film with class F fly ash as filler. The results expected from this research are producing the plastic with a better properties and durability. This research was initiated by taking the sample of HDPE plastic bottle and herbicides (containing Gramakuat, on active material parakuat dichloride at Petrokimia Kayaku Company. Both the initial HDPE and the degraded bottles was analyzed their tensile strength and Fourier Transform-Infra Red (FTIR spectral. The next step was to synthesize the HDPE plastic film using class F fly ash as filler and a coupling agent. The filler concentrations were 0%, 5%, 10%, 15%, and 20wt %. The best result was 5% filler concentration with tensile strength of 27.7 lbs. This HDPE film was then subjected to degradation test using pyridine solution with various concentrations (1%, 3% and 5% for two weeks, thermal degradation at 100 °C for two weeks and chemical resistance by xylene with soak time variation of 24 h, 98 h and 168 h. The result of degradations test show that the value of tensile strength was decreased with the increase of filler consentration. The chemical resistance, however, was increased.   Keywords: degradation, filler, fly ash, HDPE, Herbicide

Study on the Mechanical Properties of Stay Cable HDPE Sheathing Fatigue in Dynamic Bridge Environments

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Danhui Dan

2015-08-01

Full Text Available As the main force-bearing component of a cable-stayed bridge, a durable stay cable is paramount to the safety and durability of the entire bridge. High-density polyethylene (HDPE sheathing is the main protective component of a stay cable and is the key to insuring cable durability. To address the issue of HDPE sheathing fracture on service, strain level data for in-service, HDPE bridge cable sheathing was used in this study as the basis for HDPE material aging and fatigue testing. A fatigue yield phenomenon with a yield platform on the hysteresis curve of the fatigue cycles is observed by the fatigue test. The parameters to describe this phenomenon are proposed and defined in this paper. A preliminary examination of the relationship between these parameters and the factors, such as the number of cycles, the strain amplitude, and strain rate, are presented. Based on the results obtained, it is suggested that the condition of fatigue yield of HDPE sheathing be defined as the fatigue durability limit state for the purposes of durability design, assessment, and protection of cable-stayed bridges.

[Study on biocompatibility of hydroxyapatite/high density polyethylene (HA/HDPE) nano-composites artificial ossicle].

Science.gov (United States)

Wang, Guohui; Zhu, Shaihong; Tan, Guolin; Zhou, Kechao; Huang, Suping; Zhao, Yanzhong; Li, Zhiyou; Huang, Boyun

2008-06-01

This study was aimed to evaluate the biocompatibility of Hydroxyapatite/High density polyethylene (HA/ HDPE) nano-composites artificial ossicle. The percentage of S-period cells were detected by flow cytometry after L929 cells being incubated with extraction of the HA/HDPE nano-composites; the titanium materials for clinical application served as the contrast. In addition, both materials were implanted in animals and the histopathological evaluations were conducted. There were no statistically significant differences between the two groups (P >0.05). The results demonstrated that the HA/HDPE nano-composite artificial ossicle made by our laboratory is of a good biocompatibility and clinical application outlook.

Diffusion and solubility coefficients determined by permeation and immersion experiments for organic solvents in HDPE geomembrane.

Science.gov (United States)

Chao, Keh-Ping; Wang, Ping; Wang, Ya-Ting

2007-04-02

The chemical resistance of eight organic solvents in high density polyethylene (HDPE) geomembrane has been investigated using the ASTM F739 permeation method and the immersion test at different temperatures. The diffusion of the experimental organic solvents in HDPE geomembrane was non-Fickian kinetic, and the solubility coefficients can be consistent with the solubility parameter theory. The diffusion coefficients and solubility coefficients determined by the ASTM F739 method were significantly correlated to the immersion tests (pHDPE as barriers in the field.

Barrier Properties and Structural Study of Nanocomposite of HDPE/Montmorillonite Modified with Polyvinylalcohol

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María C. Carrera

2013-01-01

Full Text Available In this work was studied the permeation of CO2 in films of high-density polyethylene (HDPE and organoclay modified with polyvinylalcohol (MMTHDTMA/PVA obtained from melt blending. Permeation study showed that the incorporation of the modified organoclay generates a significant effect on the barrier properties of HDPE. When a load of 2 wt% of MMTHDTMA/PVA was incorporated in the polymer matrix, the flow of CO2 decreased 43.7% compared to pure polyethylene. The results of TEM showed that clay layers were dispersed in the polymeric matrix, obtaining an exfoliated-structure nanocomposite. The thermal stability of nanocomposite was significantly enhanced with respect to the pristine HDPE. DSC results showed that the crystallinity was maintained as the pure polymeric matrix. Consequently, the decrease of permeability was attributable only to the effect of tortuosity generated by the dispersion of MMTHDTMA/PVA. Notably the mechanical properties remain equal to those of pure polyethylene, but with an increase in barrier properties to CO2. This procedure allows obtaining nanocomposites of HDPE with a good barrier property to CO2 which would make it competitive in the use of packaging.

La calidad de la densidad urbana en Bogotá

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Óscar Alfonso Roa

2016-06-01

Full Text Available Para alojar a la creciente población de Bogotá, desde mediados del siglo pasado se prefiere aumentar la densidad en zonas residenciales que la expansión metropolitana. En este artículo se hace un análisis de la ocupación del perímetro bogotano que no se limita a los gradientes de densidad sino que integra medidas de su calidad que captan la desigualdad en materia de densidad, dotación pública, espacios libres y mezcla social. El índice resultante es una medida alternativa de la segregación socio-espacial.

Study of Crossling Agent and Couplink Agent Synergism on Mechanical Properties of HDPE-Cu Composites

International Nuclear Information System (INIS)

Mashuri; Sujud, A.A.; Karo Karo, Aloma

2001-01-01

The effects of crosslink agents, coupling agents and synergism on mechanical properties of HDPE-Cu composites materials has been investigated. The crosslink was made with dicumyl peroxide as crosslink agents of 2% concentration, so the interface adhesion of matrix-filler was made with 3-amino propyl triethoxysilane as coupling agents of 0.5% concentration. The results of research's showed, that the crosslink and interface adhesion of matrix-filler can increase tensile strength and elongation at break of HDPE-Cu composites. The synergism of two agents can increase tensile strength to 20% and elongation at break to 23% of HDPE-Cu composites materials

Elongational viscometry and bubble inflation experiments of two HDPE materials with different molecular structures

DEFF Research Database (Denmark)

Rasmussen, Henrik Koblitz; Eggen, Svein; Malmberg, Anneli

2002-01-01

The most common materials used for manufacturing of bottles and containers for household and industrial packaging has been single reactor Chromium-catalyst HDPE materials. These materials etc.......The most common materials used for manufacturing of bottles and containers for household and industrial packaging has been single reactor Chromium-catalyst HDPE materials. These materials etc....

SAXS investigation of latent track structure in HDPE irradiated with high energy Fe ions

Energy Technology Data Exchange (ETDEWEB)

Hai, Yang; Huang, Can [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Ma, Mingwang [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Institute of Electronic Engineering, CAEP, Mianyang 621900 (China); Liu, Qi; Wang, Yuzhu; Liu, Yi; Tian, Feng; Lin, Jun [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Zhu, Zhiyong, E-mail: zhuzhiyong@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China)

2015-08-01

Semi-crystalline high density polyethylene (HDPE) samples were irradiated with 1.157 GeV {sup 56}Fe ion beams to fluences ranging from 1 × 10{sup 11} to 6 × 10{sup 12} ions/cm{sup 2}. The radiation induced changes in nano/microstructure were investigated with small angle X-ray scattering (SAXS) technique. The scattering contributions from HDPE matrix and ion tracks are successfully separated and analyzed through tilted SAXS measurements with respect to the X-ray beam direction. Lorentz correction, one-dimensional correlation function calculation, fractal nature analysis of the isotropic scattering pattern reveal that HDPE long period polymeric structures are damaged and new materials, possibly clusters of carbon-rich materials, are formed inside the ion tracks. Least square curve fitting of the scattering contribution from the ion track reveals that the track is composed of a core of about 5.3 nm in radius, characterized by a significant density deficit compared to the virgin HDPE, surrounded by a shell of about 4.3 nm in thickness with less density reduction.

EVALUATION OF ULTRASONIC PHASED-ARRAY FOR DETECTION OF PLANAR FLAWS IN HIGH-DENSITY POLYETHYLENE (HDPE) BUTT-FUSION JOINTS

Energy Technology Data Exchange (ETDEWEB)

Prowant, Matthew S.; Denslow, Kayte M.; Moran, Traci L.; Jacob, Rick E.; Hartman, Trenton S.; Crawford, Susan L.; Mathews, Royce; Neill, Kevin J.; Cinson, Anthony D.

2016-09-21

The desire to use high-density polyethylene (HDPE) piping in buried Class 3 service and cooling water systems in nuclear power plants is primarily motivated by the material’s high resistance to corrosion relative to that of steel and metal alloys. The rules for construction of Class 3 HDPE pressure piping systems were originally published in Code Case N-755 and were recently incorporated into the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME BPVC) Section III as Mandatory Appendix XXVI (2015 Edition). The requirements for HDPE examination are guided by criteria developed for metal pipe and are based on industry-led HDPE research or conservative calculations.

A tomografia computadorizada de alta resolução na avaliação da toxicidade pulmonar por amiodarona High-resolution computed tomography of amiodarone pulmonary toxicity

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Daniela Peixoto Consídera

2006-04-01

Full Text Available OBJETIVO: Avaliar as principais alterações identificadas na tomografia computadorizada de alta resolução do tórax em pacientes com toxicidade pulmonar pela amiodarona. MATERIAIS E MÉTODOS: Foram avaliadas dez tomografias computadorizadas de alta resolução de tórax de pacientes com pneumonite pela amiodarona, seis desses pacientes do sexo masculino e quatro do sexo feminino, com idade média de 73,5 anos. RESULTADOS: Os achados tomográficos mais relevantes foram opacidades lineares ou reticulares em seis casos (60%, pequenos nódulos com densidade elevada em seis casos (60%, consolidações densas em três casos (30% e aumento da densidade do parênquima hepático em cinco de oito casos em que havia estudo tomográfico do abdome superior (62,5%. CONCLUSÃO: A tomografia computadorizada de alta resolução é um exame importante na avaliação de pacientes com toxicidade pulmonar pela amiodarona, devendo ser realizada sempre que houver suspeita deste diagnóstico. O achado de espessamento de septos interlobulares associado a lesões com aumento de densidade é altamente sugestivo deste diagnóstico.OBJECTIVE: To evaluate the main findings of chest high-resolution computed tomography in patients with amiodarone pulmonary toxicity. MATERIALS AND METHODS: Ten patients - six male and four female, average age of 73.5 years - with amiodarone-induced pneumonitis have undergone chest high-resolution computed tomography. RESULTS: The most relevant tomographic findings were linear or reticular opacities in six cases (60%, small high density nodules in six cases (60%, dense consolidations in three cases (30% and increased density in the hepatic parenchyma in five of eight cases in which there was a superior abdomen CT scan (62.5%. CONCLUSION: The high-resolution computed tomography is a valuable non-invasive test for evaluating patients with amiodarone pulmonary toxicity and should always be performed when one suspects of the presence of this

Modulation of Protein Adsorption and Cell Proliferation on Polyethylene Immobilized Graphene Oxide Reinforced HDPE Bionanocomposites.

Science.gov (United States)

Upadhyay, Rahul; Naskar, Sharmistha; Bhaskar, Nitu; Bose, Suryasarathi; Basu, Bikramjit

2016-05-18

The uniform dispersion of nanoparticles in a polymer matrix, together with an enhancement of interfacial adhesion is indispensable toward achieving better mechanical properties in the nanocomposites. In the context to biomedical applications, the type and amount of nanoparticles can potentially influence the biocompatibility. To address these issues, we prepared high-density polyethylene (HDPE) based composites reinforced with graphene oxide (GO) by melt mixing followed by compression molding. In an attempt to tailor the dispersion and to improve the interfacial adhesion, we immobilized polyethylene (PE) onto GO sheets by nucleophilic addition-elimination reaction. A good combination of yield strength (ca. 20 MPa), elastic modulus (ca. 600 MPa), and an outstanding elongation at failure (ca. 70%) were recorded with 3 wt % polyethylene grafted graphene oxide (PE-g-GO) reinforced HDPE composites. Considering the relevance of protein adsorption as a biophysical precursor to cell adhesion, the protein adsorption isotherms of bovine serum albumin (BSA) were determined to realize three times higher equilibrium constant (Keq) for PE-g-GO-reinforced HDPE composites as compared to GO-reinforced composites. To assess the cytocompatibility, we grew osteoblast cell line (MC3T3) and human mesenchymal stem cells (hMSCs) on HDPE/GO and HDPE/PE-g-GO composites, in vitro. The statistically significant increase in metabolically active cell over different time periods in culture for up to 6 days in MC3T3 and 7 days for hMSCs was observed, irrespective of the substrate composition. Such observation indicated that HDPE with GO or PE-g-GO addition (up to 3 wt %) can be used as cell growth substrate. The extensive proliferation of cells with oriented growth pattern also supported the fact that tailored GO addition can support cellular functionality in vitro. Taken together, the experimental results suggest that the PE-g-GO in HDPE can effectively be utilized to enhance both mechanical and

On the Injection Molding Processing Parameters of HDPE-TiO2 Nanocomposites

Science.gov (United States)

Mourad, Abdel-Hamid I.; Mozumder, Mohammad Sayem; Mairpady, Anusha; Pervez, Hifsa; Kannuri, Uma Maheshwara

2017-01-01

In recent years, the development and use of polymeric nanocomposites in creating advanced materials has expanded exponentially. A substantial amount of research has been done in order to design polymeric nanocomposites in a safe and efficient manner. In the present study, the impact of processing parameters, such as, barrel temperature, and residence time on the mechanical and thermal properties of high density polyethylene (HDPE)-TiO2 nanocomposites were investigated. Additionally, scanning electron microscopy and X-ray diffraction spectroscopy were used to analyze the dispersion, location, and phase morphology of TiO2 on the HDPE matrix. Mechanical tests revealed that tensile strength of the fabricated HDPE-TiO2 nanocomposites ranged between 22.53 and 26.30 MPa, while the Young’s modulus showed a consistent increase as the barrel temperature increased from 150 °C to 300 °C. Moreover, the thermal stability decreased as the barrel temperature increased. PMID:28772444

Life cycle assessment of a road safety product made with virgin and recycled HDPE.

Science.gov (United States)

Simões, Carla L; Xará, Susana M; Bernardo, C A

2011-04-01

The present study aims at evaluating the potential environmental impact of using recycled high-density polyethylene (HDPE) in the production of an anti-glare lamella (AGL), a road safety device currently manufactured from virgin (not recycled) polymer. The impact was evaluated using the life cycle assessment (LCA) technique and comparing two alternative systems: current AGL, manufactured from virgin HDPE, and optional AGL, made with recycled HDPE obtained from post-consumer packages. The AGL manufacturing phase was found to be responsible for most of the impacts in both systems, with the production of the raw material being the largest contributor for that phase. The present study makes a contribution to the problem of developing value-added products made from post-consumer polymeric recyclates.

A study on thermal and mechanical properties of mechanically milled HDPE and PP

International Nuclear Information System (INIS)

Can, S.; Tan, S.

2003-01-01

In this study, mechanical mixing of HDPE and PP was performed via ball milling. Prepared compositions were 75/25 , 50/50 , 25/75 w/w HDPE/PP. Milling time and ball to powder ratio (B/P) were kept constant and system was cooled by adding solid CO 2 to improve the milling efficiency. To compare these systems with traditional methods, mixtures were also melt mixed by Brabender Plasti-Corder. Both milled and melt mixed systems were examined with DSC for thermal properties and tensile testing for mechanical properties Results are discussed by comparing milled , melt mixed and as-received polymers. It is observed that, unlike ball milled systems' in melt mixed systems mechanical properties are composition dependent. In addition , ball milling results in amorphization of both polymers and very high amounts of PP (75wt %) creates very amorphous HDPE structure. (Original)

KARAKTERISTIK MORFOLOGI, TERMAL, FISIK-MEKANIK, DAN BARRIER PLASTIK BIODEGRADABEL BERBAHAN BAKU KOMPOSIT PATI TERMOPLASTIK-LLDPE/HDPE

Directory of Open Access Journals (Sweden)

Waryat Waryat

2013-08-01

  ABSTRAK   Plastik sebagai kemasan suatu produk sudah banyak dipakai dan digunakan dalam kurun waktu lama. Namun, limbah plastik tersebut dapat menimbulkan pencemaran lingkungan dikarenakan plastik sulit untuk terdegradasi oleh mikroorganisme. Usaha untuk mengurangi ketergantungan terhadap plastik salah satunya adalah penggunaan plastik ramah lingkungan dari bahan baku yang dapat diperbaruhi dengan metode pencampuran/blending. Permasalahan yang dihadapi dalam pembuatan plastik biodegradabel berbahan baku campuran antara bahan alami dan sintetis adalah tidak kompatibel antara kedua bahan tersebut karena bahan alami bersifat hidrofilik/polar dan bahan sintetis bersifat hidrofobik/non polar. Untuk meningkatkan kompatibilitas antara kedua campuran itu perlu ditambahkan bahan seperti compatibilizer. Tujuan penelitian ini adalah untuk mengetahui karakteristik morfologi permukaan plastik, kecepatan alir, densitas, suhu leleh, sifat mekanik, dan barrier pastik biodegradabel berbahan baku campuran pati termoplastik-LLDPE/HDPE. Penelitian ini dibagi menjadi tiga tahap yaitu pembuatan pati termoplastik, pembuatan compatibilizer LLDPE/HDPE-g-MA dan pembuatan plastik biodegradabel. Karakteristik sifat aliran, kekuatan tarik, perpanjangan putus, dan permeabilitas oksigen plastik biodegradabel berbahan baku pati termoplastik-LLDPE/HDPE cenderung menurun, sedangkan karakteristik permeabilitas terhadap uap air cenderung meningkat dengan semakin meningkatnya kandungan pati termoplastik. Adanya compatibilizer LLDPE/HDPE-g-MA menghasilkan sifat mekanik lebih baik pada plastik biodegradabel. Kata kunci: plastik biodegradabel, pati termoplastik, compatibilizer MA-g-LLDPE/HDPE

Effects of electron-beam irradiation on HDPE/Brazil nut shell fiber composite

Energy Technology Data Exchange (ETDEWEB)

Ferreira, Maiara S.; Sartori, Mariana N.; Oliveira, Rene R.; Moura, Esperidiana A.B., E-mail: maiara.sferreira@gmail.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2013-07-01

In recent years, research on the replacement of synthetic fibers by natural fibers as reinforcement in thermoplastic composites has increased dramatically due to the advantages of natural fibers, such as low density, low cost, environmental appeal and recyclability. In the present work, the influence of electron-beam irradiation on mechanical properties of HDPE and HDPE/Brazil Nut Shell (Bertholletia excelsa) fiber compositive was investigated. The HDPE composite reinforced with 5% or 10%, by weight of Brazil nut shell fiber powder with particle sizes equal or smaller than 250 μm were obtained by extrusion, using a twin screw extruder. The materials were irradiated at 200 kGy using a 1.5 MeV electron beam accelerator, at room temperature in presence of air. The irradiated and non-irradiated specimens tests samples were submitted to mechanical and thermo-mechanical tests, scanning electron microscopy (SEM), X-Ray diffraction (XRD) and sol-gel analysis and the correlation between their properties was discussed. The results showed significant changes in HDPE mechanical and thermo-mechanical properties due to Brazil nut shell fibers addition and electron-beam irradiation. The surface of the cryo fractured composite samples irradiated showed important visual changes which suggest a better fiber-matrix interfacial adhesion, due to irradiation treatment. These results showed that it is possible to get interesting property gains by using waste from renewable sources instead of the traditional ones and electron-beam radiation treatment. (author)

Effects of electron-beam irradiation on HDPE/Brazil nut shell fiber composite

International Nuclear Information System (INIS)

Ferreira, Maiara S.; Sartori, Mariana N.; Oliveira, Rene R.; Moura, Esperidiana A.B.

2013-01-01

In recent years, research on the replacement of synthetic fibers by natural fibers as reinforcement in thermoplastic composites has increased dramatically due to the advantages of natural fibers, such as low density, low cost, environmental appeal and recyclability. In the present work, the influence of electron-beam irradiation on mechanical properties of HDPE and HDPE/Brazil Nut Shell (Bertholletia excelsa) fiber compositive was investigated. The HDPE composite reinforced with 5% or 10%, by weight of Brazil nut shell fiber powder with particle sizes equal or smaller than 250 μm were obtained by extrusion, using a twin screw extruder. The materials were irradiated at 200 kGy using a 1.5 MeV electron beam accelerator, at room temperature in presence of air. The irradiated and non-irradiated specimens tests samples were submitted to mechanical and thermo-mechanical tests, scanning electron microscopy (SEM), X-Ray diffraction (XRD) and sol-gel analysis and the correlation between their properties was discussed. The results showed significant changes in HDPE mechanical and thermo-mechanical properties due to Brazil nut shell fibers addition and electron-beam irradiation. The surface of the cryo fractured composite samples irradiated showed important visual changes which suggest a better fiber-matrix interfacial adhesion, due to irradiation treatment. These results showed that it is possible to get interesting property gains by using waste from renewable sources instead of the traditional ones and electron-beam radiation treatment. (author)

Biocompatibility evaluation of HDPE-UHMWPE reinforced β-TCP nanocomposites using highly purified human osteoblast cells.

Science.gov (United States)

Shokrgozar, M A; Farokhi, M; Rajaei, F; Bagheri, M H A; Azari, Sh; Ghasemi, I; Mottaghitalab, F; Azadmanesh, K; Radfar, J

2010-12-15

Biocompatibility of β-TCP/HDPE-UHMWPE nanocomposite as a new bone substitute material was evaluated by using highly purified human osteoblast cells. Human osteoblast cells were isolated from bone tissue and characterized by immunofluorescence Staining before and after purification using magnetic bead system. Moreover, proliferation, alkaline phosphatase production, cell attachment, calcium deposition, gene expression, and morphology of osteoblast cells on β-TCP/HDPE-UHMWPE nanocomposites were evaluated. The results have shown that the human osteoblast cells were successfully purified and were suitable for subsequent cell culturing process. The high proliferation rate of osteoblast cells on β-TCP/HDPE-UHMWPE nanocomposite confirmed the great biocompatibility of the scaffold. Expression of bone-specific genes was taken place after the cells were incubated in composite extract solutions. Furthermore, osteoblast cells were able to mineralize the matrix next to composite samples. Scanning electron microscopy demonstrated that cells had normal morphology on the scaffold. Thus, these results indicated that the nanosized β-TCP/HDPE-UHMWPE blend composites could be potential scaffold, which is used in bone tissue engineering. Copyright © 2010 Wiley Periodicals, Inc.

The Effects of Coupling Agents on the Mechanical and Thermal Properties of Eucalyptus Flour/HDPE Composite

Directory of Open Access Journals (Sweden)

Metanawin Siripan

2015-01-01

Full Text Available The aim of this research was to study the effects of the coupling agents, FusabondTM E-528 (polyethylene-grafted maleic anhydride; PE-g-MA, MA and Amino Silane (Si, on the thermal properties, and mechanical properties of Eucalyptus flour-HDPE composite. Variation of the Eucalyptus flour contents in the HDPE resulted in properties of the composite. With increasing in the contents of Eucalyptus flour in polymer matrix, the mechanical properties of the HDPE composite decreased in EU-MA series samples while they were gradually decreased in EU-Si series samples. SEM micrographs showed the fracture surface of the HDPE/Eucalyptus composite at different ratios of Eucalyptus flour. SEM micrograpgh exhibited the dispersion of EU flour in polymer matrix. The samples of both coupling agents showed an increase in interfacial adhesion, observed for the considerable decreased of gaps between the matrix and the dispersed phase. However, the EU-MA sample appeared to be more uniformly than the EU-Si sample.

Temperature and loading frequency effects of fatigue crack growth in HDPE pipe material

International Nuclear Information System (INIS)

Merah, N.; Khan, Z.; Bazoune, A.; Saghir, F.

2006-01-01

High density polyethylene (HDPE) pipes are being extensively used for gas, water, sewage and waste water distribution systems. Laboratory tests appear to show that HDPE is more able to suppress rapid crack propagation, while remaining somehow resistant to slow crack growth failures observed in service. Procedures for estimating pipe life in service have been established by making use of fatigue crack growth (FCG) results. These procedures are concerned mainly with room temperature. Applications with some safety factor to include the temperature effect. Use of HDPE pipes in water and gas distribution in the Gulf area has seen a net increase. This study addresses the combined effects of temperature and frequency on FCG properties of commercial HDPE pipe material. FCG accelerated tests were conducted on single-etch notch (SEN) specimens in the temperature range of -10 to 70C at frequencies ranging from 0.1 to 50 Hz. The FCG tests are conducted at a stress amplitude level approximately 1/4 of room temperature yield stress and crack growth behavior was investigated using linear elastic fracture mechanics concepts. The stress intensity range delta K gave satisfactory correlation of crack, growth rate (da/dN) at the temperatures of -10, 0, 23 and 40C and at frequencies of 0.1, 1, and 50 Hz. The crack growth resistance was found to decrease with increase in test temperature and decrease growth resistance was found to decrease with increase in test temperature and decrease with frequency. For 70C no crack propagation was observed, the failure was observed to occur by collapse or generalized yielding. Fractographic analyses results are used to explain temperature and frequency effects on FCG. The effect of temperature on da/dN for HDPE material was investigated by considering the variation of mechanical properties with temperature. Master curves were developed by normalizing delta K yield stress. (author)

Comparison of rheological, mechanical, electrical properties of HDPE filled with BaTiO{sub 3} with different polar surface tension

Energy Technology Data Exchange (ETDEWEB)

Su, Jun [Department of Polymer Science and Engineering, College of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009 (China); College of Mechanics Engineering, Nanjing Institute of Industry Technology, Nanjing, 210023 (China); Zhang, Jun, E-mail: zhangjun@njtech.edu.cn [Department of Polymer Science and Engineering, College of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009 (China)

2016-12-01

Graphical abstract: - Highlights: • The non-polar and short vinyl groups can greatly reduce G′ of HDPE composites. • Long chains on BaTiO{sub 3} surface enhance the interaction of BaTiO{sub 3} with HDPE. • Polar amino groups on BaTiO{sub 3} surface raise the interaction of BaTiO{sub 3} with HDPE. • Polar amino groups can boost the dielectric constant of HDPE composites. • The potential use in electronic equipment of the KH550 composites is obtained. - Abstract: In this work, three types of coupling agents: isopropyl trioleic titanate (NDZ105), vinyltriethoxysilane (SG-Si151), 3-aminopropyltriethoxysilane (KH550) were applied to modify the surface tension of Barium titanate (BaTiO{sub 3}) particles. The Fourier transform infrared (FT-IR) spectra confirm the chemical adherence of coupling agents to the particle surface. The long hydrocarbon chains in NDZ105 can cover the particle surface and reduce the polar surface tension of BaTiO{sub 3} from 37.53 mJ/m{sup 2} to 7.51 mJ/m{sup 2}, turning it from hydrophilic to oleophilic properties. The short and non-polar vinyl groups in SG-Si151 does not influence the surface tension of BaTiO{sub 3}, but make BaTiO{sub 3} have both hydrophilic and oleophilic properties. The polar amino in KH550 can keep BaTiO{sub 3} still with hydrophilic properties. It is found that SG-Si151 modified BaTiO{sub 3} has the lowest interaction with HDPE matrix, lowering the storage modulus of HDPE composites to the greatest extent. As for mechanical properties, the polar amino groups in KH550 on BaTiO{sub 3} surface can improve the adhesion of BaTiO{sub 3} with HDPE matrix, which increases the elongation at break of HDPE composites to the greatest extent. In terms of electrical properties, the polar amino groups on surface of BaTiO{sub 3} can boost the dielectric properties of HDPE/BaTiO{sub 3} composites and decrease the volume resistivity of HDPE/BaTiO{sub 3} composites. The aim of this study is to investigate how functional groups

Synthesis of manganese stearate for high density polyethylene (HDPE) and its biodegradation

Science.gov (United States)

Aras, Neny Rasnyanti M.; Arcana, I. Made

2015-09-01

An oxidant additive is one type of additive used for oxo-biodegradable polymers. This additive was prepared by reaction multivalent transition metals and fatty acids to accelerate the degradation process of polymers by providing a thermal treatment or irradiation with light. This study focused on the synthesis of manganese stearate as an additive for application in High Density Polyethylene (HDPE), and the influence of manganese stearate on the characteristics of HDPE including their biodegradability. Manganese stearate was synthesized by the reaction of stearic acid with sodium hydroxide, and sodium stearate formed was reacted with manganese chloride tetrahydrate to form manganese stearate with a melting point of 100-110 °C. Based on the FTIR spectrum showed absorption peak at wave number around 1560 cm-1 which is an asymmetric vibration of CO functional group that binds to the manganese. The films of oxo-biodegradable polymer were prepared by blending HDPE and manganese stearate additives at various concentrations with using the polymer melting method, followed heating at a temperature of 50°C and 70°C for 10 days. The characterizations of the oxo-biodegradable polymers were carried out by analysis the functional groups (FTIR and ATR),thermal properties (TGA), surface properties (SEM), as well as analysis of the biodegradability (the biodegradation test by using activated sludge, % weight loss). Based on COi indicate that the additive of manganese stearate is active in oxidizing polymer by heating treatment. Results of biodegradation by microorganisms from activated sludge showed that the percentage weight loss of polymers increase with the increasing incubation time and the concentration of manganese stearate in HDPE. Biodegradability of HDPE with the addition of manganese stearate and followed by heating at a higher temperature was better observed. The highest percentage weight loss was obtained at the polymer with concentration of 0.2% manganese stearate

Synthesis of manganese stearate for high density polyethylene (HDPE) and its biodegradation

Energy Technology Data Exchange (ETDEWEB)

Aras, Neny Rasnyanti M., E-mail: neny.rasnyanti@gmail.com; Arcana, I Made, E-mail: arcana@chem.itb.ac.id [Inorganic and Physical Chemistry Research Division, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jalan Ganesha 10, Bandung 40132 (Indonesia)

2015-09-30

An oxidant additive is one type of additive used for oxo-biodegradable polymers. This additive was prepared by reaction multivalent transition metals and fatty acids to accelerate the degradation process of polymers by providing a thermal treatment or irradiation with light. This study focused on the synthesis of manganese stearate as an additive for application in High Density Polyethylene (HDPE), and the influence of manganese stearate on the characteristics of HDPE including their biodegradability. Manganese stearate was synthesized by the reaction of stearic acid with sodium hydroxide, and sodium stearate formed was reacted with manganese chloride tetrahydrate to form manganese stearate with a melting point of 100-110 °C. Based on the FTIR spectrum showed absorption peak at wave number around 1560 cm{sup −1} which is an asymmetric vibration of CO functional group that binds to the manganese. The films of oxo-biodegradable polymer were prepared by blending HDPE and manganese stearate additives at various concentrations with using the polymer melting method, followed heating at a temperature of 50°C and 70°C for 10 days. The characterizations of the oxo-biodegradable polymers were carried out by analysis the functional groups (FTIR and ATR),thermal properties (TGA), surface properties (SEM), as well as analysis of the biodegradability (the biodegradation test by using activated sludge, % weight loss). Based on COi indicate that the additive of manganese stearate is active in oxidizing polymer by heating treatment. Results of biodegradation by microorganisms from activated sludge showed that the percentage weight loss of polymers increase with the increasing incubation time and the concentration of manganese stearate in HDPE. Biodegradability of HDPE with the addition of manganese stearate and followed by heating at a higher temperature was better observed. The highest percentage weight loss was obtained at the polymer with concentration of 0.2% manganese

Synthesis of manganese stearate for high density polyethylene (HDPE) and its biodegradation

International Nuclear Information System (INIS)

Aras, Neny Rasnyanti M.; Arcana, I Made

2015-01-01

An oxidant additive is one type of additive used for oxo-biodegradable polymers. This additive was prepared by reaction multivalent transition metals and fatty acids to accelerate the degradation process of polymers by providing a thermal treatment or irradiation with light. This study focused on the synthesis of manganese stearate as an additive for application in High Density Polyethylene (HDPE), and the influence of manganese stearate on the characteristics of HDPE including their biodegradability. Manganese stearate was synthesized by the reaction of stearic acid with sodium hydroxide, and sodium stearate formed was reacted with manganese chloride tetrahydrate to form manganese stearate with a melting point of 100-110 °C. Based on the FTIR spectrum showed absorption peak at wave number around 1560 cm −1 which is an asymmetric vibration of CO functional group that binds to the manganese. The films of oxo-biodegradable polymer were prepared by blending HDPE and manganese stearate additives at various concentrations with using the polymer melting method, followed heating at a temperature of 50°C and 70°C for 10 days. The characterizations of the oxo-biodegradable polymers were carried out by analysis the functional groups (FTIR and ATR),thermal properties (TGA), surface properties (SEM), as well as analysis of the biodegradability (the biodegradation test by using activated sludge, % weight loss). Based on COi indicate that the additive of manganese stearate is active in oxidizing polymer by heating treatment. Results of biodegradation by microorganisms from activated sludge showed that the percentage weight loss of polymers increase with the increasing incubation time and the concentration of manganese stearate in HDPE. Biodegradability of HDPE with the addition of manganese stearate and followed by heating at a higher temperature was better observed. The highest percentage weight loss was obtained at the polymer with concentration of 0.2% manganese

Case study installation of a HDPE curtain wall with sheetpile tie-in on both ends

International Nuclear Information System (INIS)

Schindler, R.M.; Maltese, P.C.

1997-01-01

The plans for eliminating the off-site migration of non-aqueous phase liquid (NAPL) from a refinery into a nearby river included the installation of a High Density Polyethylene (HDPE) curtain wall and an underdrain system. A 640 m (2100 lineal feet) HDPE Curtain Wall was installed along the river boundary, tying into an existing sheet pile wall on both ends. The wall varied from approximately 4.5 m (15 feet) deep at the northern end to about 7 m (23 feet) deep at the southern end, running approximately 3 to 3.6 m (10 to 12 feet) inland of an existing wooden bulkhead. The curtain wall was successfully installed through a slurry supported trench. A 930 m (3050 lineal feet) interception/collection trench was installed parallel to the HDPE Curtain Wall, continuing on beyond the curtain wall on the southern end. The depth of the trench varied from approximately 3 to 4 m (10 to 13 feet) deep. A 20.32 cm (8 inch) diameter perforated HDPE header pipe was placed in the trench to convey groundwater and product to two sumps. The trench is 53.34 cm (21 inches) wide and contained aggregate to approximately 0.9 m (3 feet) below ground. This work was accomplished using the bio-polymer slurry drainage trench (BP Drain) technique. This paper briefly describes the construction methods utilized during this project, specifically HDPE curtain wall installation thru a bentonite slurry and tie-in to the existing sheet pile wall

Effect of gamma radiation and accelerated aging on the mechanical and thermal behavior of HDPE/HA nano-composites for bone tissue regeneration.

Science.gov (United States)

Alothman, Othman Y; Almajhdi, Fahad N; Fouad, H

2013-09-24

The replacement of hard tissues demands biocompatible and sometimes bioactive materials with properties similar to those of bone. Nano-composites made of biocompatible polymers and bioactive inorganic nano particles such as HDPE/HA have attracted attention as permanent bone substitutes due to their excellent mechanical properties and biocompatibility. The HDPE/HA nano-composite is prepared using melt blending at different HA loading ratios. For evaluation of the degradation by radiation, gamma rays of 35 kGy, and 70 kGy were used to irradiate the samples at room temperature in vacuum. The effects of accelerated ageing after gamma irradiation on morphological, mechanical and thermal properties of HDPE/HA nano-composites were measured. In Vitro test results showed that the HDPE and all HDPE/HA nano-composites do not exhibit any cytotoxicity to WISH cell line. The results also indicated that the tensile properties of HDPE/HA nano-composite increased with increasing the HA content except fracture strain decreased. The dynamic mechanical analysis (DMA) results showed that the storage and loss moduli increased with increasing the HA ratio and the testing frequency. Finally, it is remarked that all properties of HDPE/HA is dependent on the irradiation dose and accelerated aging. Based on the experimental results, it is found that the addition of 10%, 20% and 30% HA increases the HDPE stiffness by 23%, 44 and 59% respectively. At the same time, the G' increased from 2.25E11 MPa for neat HDPE to 4.7E11 MPa when 30% HA was added to the polymer matrix. Also, significant improvements in these properties have been observed due to irradiation. Finally, the overall properties of HDPE and its nano-composite properties significantly decreased due to aging and should be taken into consideration in the design of bone substitutes. It is attributed that the developed HDPE/HA nano-composites could be a good alternative material for bone tissue regeneration due to their acceptable

Preparation and characterization of high density polyethylene and residual fibre of Attalea funifera Mart (piacava) composites; Preparacao e caracterizacao de compositos de polietileno de alta densidade com residuos de fibras de piacava da especie Attalea funifera Mart

Energy Technology Data Exchange (ETDEWEB)

Agrela, Sara P.; Guimaraes, Danilo H.; Jose, Nadia M., E-mail: saraagrela@hotmail.co [Universidade Federal da Bahia (GECIM/IQ/UFBA), Salvador, BA (Brazil). Inst. de Quimica. Grupo de Energia e Ciencias dos Materiais; Carvalho, Gleidson G.P. [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Escola de Medicina Veterinaria. Dept. de Producao Animal; Carvalho, Ricardo F. [Universidade Federal da Bahia (EP/UFBA), Salvador, BA (Brazil). Escola Politecnica. Curso de Mestrado em Engenharia Ambiental Urbana

2009-07-01

The use of natural fiber reinforcement thermoplastic polymer is continuously increasing. This fact is manly due to its advantages as low cost, availability, recyclability, low energy demand and then environmental appeal if compared to synthetics fibers. The composites were prepared in different fiber volume ratios (5%, 10% and 20%) mixed with high density polyethylene (HDPE) and heated at 190 deg C. Thermogravimetric analysis and differential scanning calorimetry were used to investigate thermal stability. The composites structure was characterized by Fourier Transform Infrared spectroscopy, X-ray diffractometry. Fiber and residue of piassava (Attalea funifera Mart) chemical composition were determined by Van Soest Method. The results indicate that thermo stability of the composites of HDPE prepared with fiber volume ratios up to 20% is only slightly lowered. (author)

Structural characterization of HDPE/LLDPE blend-based nano composites obtained by different blending sequence

International Nuclear Information System (INIS)

Passador, Fabio R.; Ruvolo Filho, Adhemar; Pessan, Luiz A.

2011-01-01

The blending sequence affects the morphology formation of the nanocomposites. In this work, the blending sequences were explored to determine its influence in the rheological behavior of HDPE/LLDPE/OMMT nanocomposites. The nanocomposites were obtained by melt-intercalation using a mixture of LLDPE-g-MA and HDPE-g-MA as compatibilizer system in a torque rheometer at 180 deg C and five blending sequences were studied. The materials structures were characterized by wide angle X-ray diffraction (WAXD) and by rheological properties. The nanoclay's addition increased the shear viscosity at low shear rates, changing the behavior of HDPE/LLDPE matrix to a Bingham model behavior with an apparent yield stress. Intense interactions were obtained for the blending sequence where LLDPE and/or LLDPE-g-MA were first reinforced with organoclay since the intercalation process occurs preferentially in the amorphous phase. (author)

Influence of the surfactant in the shear-induced crystallization kinetics of HDPE/MMT nano composites; Influencia do tratamento superficial da montmorilonita na cinetica de cristalizacao induzida por fluxo de nanocompositos de HDPE

Energy Technology Data Exchange (ETDEWEB)

Bonel, A.B. [Universidade Federal de Sao Carlos (DEMA/UFSCAR), SP (Brazil). Dept. de Engenharia de Materiais; Beatrice, C.A.G.; Marini, J.; Bretas, R.E.S., E-mail: bretas@ufscar.b [Universidade Federal de Sao Carlos (UFSCAR), SP (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais

2010-07-01

High-density polyethylene (HDPE) compatibilized with ethylene vinyl-acetate copolymer (EVA)r, with 5 wt% of two different organically modified montmorillonite (with polar and non-polar surfactant) were prepared by melt blending in a corrotational twin-screw extruder at 225 deg C, 100rpm and 3kg/h. Both nanocomposites were characterized by wide-angle x-ray scattering (WAXS), transmission electron microscopy (TEM) and rheological measurements. The nanoclay's lamellas were intercalated in both samples. The storage and the loss moduli of the nanocomposites, at low frequencies, showed that the particles of the nanoclay modified with a polar surfactant were well dispersed thru the HDPE matrix, while the particles of the other nanoclay were well distributed thru the matrix. The presence of a nanoclay modified with a non-polar surfactant reduced the induction times for the crystals growth, due to the strong interactions with the HDPE chains. (author)

Quality monitoring of salt produced in Indonesia through seawater evaporation on HDPE geomembrane lined ponds

Science.gov (United States)

Jumaeri; Sulistyaningsih, T.; Alighiri, D.

2018-03-01

Salt is one of the primary ingredients that humans always need for various purposes, both for consumption and industry. The need for high-quality salt continues to increase, as long as industry growth. It must improve product quality through the development of salt production process technology. In this research, the quality monitoring of salt produced in Indonesia by evaporation of seawater on ponds lined using high-density polyethylene (HDPE) geomembrane has been studied. The manufacturing of salt carried out through the gradual precipitation principle on prepared ponds. HDPE geomembrane is used to coat evaporation ponds with viscosity 12-22°Be and crystallization ponds with a viscosity of 23°Be. The monitoring of the product is carried out in the particular periods during the salt production period. The result of control shows that the quality of salt produced in HDPE geomembrane coated salt ponds has an average NaCl content of 95.75%, so it has fulfilled with Indonesia National Standard (SNI), that is NaCl> 94.70%. The production of salt with HDPE geomembrane can improve the quality of salt product from NaCl 85.4% (conventional system) to 95.75%.

Application of glass particles doped by Zn+2 as an antimicrobial and atoxic compound in LLDPE and HDPE

International Nuclear Information System (INIS)

Santos, M.F.; Machado, C.; Tachinski, C.G.; Júnior, J.F.; Piletti, R.; Peterson, M.; Fiori, M.A.

2014-01-01

This study demonstrates the potential application of glass particles doped with Zn +2 (GZn) as an atoxic, antimicrobial additive when used in conjunction with high density polyethylene (HDPE) and linear low density polyethylene (LLDPE) polymers. Toxicity tests demonstrated that these modified glass particles were nontoxic to human cells, and atomic absorption analyses demonstrated the migration of ionic species in quantities less than 2.0 ppm for both the HDPE/GZn and LLDPE/GZn compounds. Microbiological tests demonstrated the antimicrobial effect of the pure GZn compound as well as the polymeric HDPE/GZn and LLDPE/GZn compounds. In addition, at percentages of GZn higher than 2.00 wt.% and at a time of 4 h, the bactericidal performance is excellent and equal for both polymeric compounds. - Highlights: • Glass doped with Zn +2 (GZn) promoted a good bactericidal properties in LLDPE and HDPE. • LLDPE and HDPE doped with GZn have capacity of liberty ionic zinc during a time period. • GZn is not toxic to human and can be used with antimicrobial additive to polymers. • GZn has an antimicrobial effect in bacteria type Gram positive and Gram negative

Environmental and economic assessment of a road safety product made with virgin and recycled HDPE: a comparative study.

Science.gov (United States)

L Simões, Carla; Costa Pinto, Lígia M; Bernardo, C A

2013-01-15

The development of value-added products made from post-consumer plastic recyclates has become an important goal in the quest for a sustainable society. To attain such goal, tools with higher accuracy and wider scope are increasingly necessary. The present work describes the application of a Life Cycle Assessment (LCA)/Life Cycle Costing (LCC) integrated model, with inclusion of externalities (environmental and social costs), to Anti-Glare Lamellae (AGL) made with High Density Polyethylene (HDPE). It compares an AGL currently manufactured from virgin HDPE (current AGL) with an alternative one made with recycled HDPE (optional AGL). The results obtained show that neither the current nor the optional AGL depict the best environmental performance in all impact categories. Nevertheless, there is a clear overall environmental and economic advantage in replacing virgin HDPE with recycled HDPE. The present work also makes evident that the LCA/LCC integrated model allows the identification of economic and environmental win-win and trade-off situations related to the full life cycle of products. As such, its results can be used as valuable guidelines in product development. Copyright © 2012 Elsevier Ltd. All rights reserved.

Surface chemistry changes of weathered HDPE/wood-flour composites studied by XPS and FTIR spectroscopy

Science.gov (United States)

Nicole M. Stark; Laurent M. Matuana

2004-01-01

The use of wood-derived fillers by the thermoplastic industry has been growing, fueled in part by the use of wood-fiber–thermoplastic composites by the construction industry. As a result, the durability of wood-fiber– thermoplastic composites after ultraviolet exposure has become a concern. Samples of 100% high-density polyethylene (HDPE) and HDPE filled with 50% wood-...

The Tension and Puncture Properties of HDPE Geomembrane under the Corrosion of Leachate.

Science.gov (United States)

Xue, Qiang; Zhang, Qian; Li, Zhen-Ze; Xiao, Kai

2013-09-17

To investigate the gradual failure of high-density polyethylene (HDPE) geomembrane as a result of long-term corrosion, four dynamic corrosion tests were conducted at different temperatures and durations. By combining tension and puncture tests, we systematically studied the variation law of tension and puncture properties of the HDPE geomembrane under different corrosion conditions. Results showed that tension and puncture failure of the HDPE geomembrane was progressive, and tensile strength in the longitudinal grain direction was evidently better than that in the transverse direction. Punctures appeared shortly after puncture force reached the puncture strength. The tensile strength of geomembrane was in inversely proportional to the corrosion time, and the impact of corrosion was more obvious in the longitudinal direction than transverse direction. As corrosion time increased, puncture strength decreased and corresponding deformation increased. As with corrosion time, the increase of corrosion temperature induced the decrease of geomembrane tensile strength. Tensile and puncture strength were extremely sensitive to temperature. Overall, residual strength had a negative correlation with corrosion time or temperature. Elongation variation increased initially and then decreased with the increase in temperature. However, it did not show significant law with corrosion time. The reduction in puncture strength and the increase in puncture deformation had positive correlations with corrosion time or temperature. The geomembrane softened under corrosion condition. The conclusion may be applicable to the proper designing of the HDPE geomembrane in landfill barrier system.

Coupling of HDPE/hydroxyapatite composites by silane-based methodologies.

Science.gov (United States)

Sousa, R A; Reis, R L; Cunha, A M; Bevis, M J

2003-06-01

Several coupling treatments based on silane chemicals were investigated for the development of high density (HDPE)/hydroxyapatite (HA) composites. Two HA powders, sintered HA (HAs) and non sintered HA (HAns), were studied in combination with five silanes, namely y-methacryloxy propyltrimethoxy silane (MEMO), 3-(2-aminoethyl)aminopropyltrimethoxy silane (DAMO), vinyltrimethoxy silane (VTMO), 3-aminopropyltriethoxy silane (AMEO) and trimethoxypropyl silane (PTMO). The HA particles were treated by a dipping in method or by spraying with silane solutions. After drying, the treated powders were compounded with HDPE or HDPE with acrylic acid and/or organic peroxide and subsequently compression molded. The tensile test specimens obtained from the molded plates were tensile tested and their fracture surfaces were observed by scanning electron microscopy (SEM). For the sintered HA (HAs) composites, the most effective coupling treatments concerning stiffness are those based on MEMO and AMEO. The low influence of these coupling procedures on strength is believed to be associated to the low volume fraction and the relatively smooth surface of the used HA particles. For the non-sintered HA (HAns) composites, it was possible to improve significantly both the stiffness and the strength. Amino silanes demonstrated to be highly efficient concerning strength enhancement. The higher effectiveness of the coupling treatments for HAns filled composites is attributed to their higher particle surface area, smaller particle size distribution and expected higher chemical reactivity. For both cases, the improvement in mechanical performance after the coupling treatment is consistent with the enhancement in interfacial adhesion observed by SEM.

Consumo de alimentos de alta densidad energética en los beneficiarios del programa Oportunidades. El caso del Área Metropolitana de Monterrey

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Óscar Alfonso Martínez Martínez

2012-01-01

refrescos y frituras, entre los beneficiarios y no beneficiarios de dicho programa. Se encontró que no existen diferencias estadísticamente significativas en su consumo, pero sí que las ingestas son altas para ambos grupos.

Estudo da influência de resíduos catalíticos na degradação de plásticos reciclados (Blenda HDPE/PP e PET provenientes de lixo urbano

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Santos Amélia S. F.

1999-01-01

Full Text Available A degradação derivada do processamento, uso, descarte, lavagem e reprocessamento foram caracterizados neste estudo. Para o HDPE/PP pós-consumo, a degradação foi estudada em função da presença de garrafas de HDPE/LDPE reprocessadas (recicladas e da presença de tampas e rótulos de LDPE e PP. Esses materiais mostraram uma influência significativa na degradação total de HDPE/PP apenas quando presentes em conjunto. Os resíduos que apresentaram menor estabilidade termo-oxidativa foram os rótulos e tampas de LDPE e PP. As análises usadas na caracterização da influência destes resíduos foram espectroscopia do Infra-vermelho (IR e Calorimetria Diferencial Exploratória (tempo de indução oxidativa - OIT. Além disso, a degradação do PET foi estudada em função das condições de lavagem e da presença de resíduos de soda cáustica e adesivo. Foram usadas medidas de viscosidade intrínseca e de titulação para caracterizar estas variáveis. Foi observado que apesar do uso de altas temperaturas (80 ºC durante a lavagem, a extensão de tempo desta etapa (5 ou 15 min não afetou a degradação do PET, pelo menos não em níveis detectáveis pelas análises. No entanto, a remoção do resíduo de adesivo mostrou uma influência significativa na degradação catalítica do PET.

Effect of TiO2 Nanofiller Concentration on the Mechanical, Thermal and Biological Properties of HDPE/TiO2 Nanocomposites

Science.gov (United States)

Mozumder, Mohammad Sayem; Mourad, Abdel-Hamid I.; Mairpady, Anusha; Pervez, Hifsa; Haque, Md Emdadul

2018-05-01

The necessity for advanced and effective biomimetic tissue engineering materials has increased massively as bone diseases such as osteoporosis and bone cancer have become a major public health problem. Therefore, the objective of this study is to develop titanium dioxide (TiO2) nanoparticles-enriched high-density polyethylene (HDPE) nanocomposites that could serve as potential biomaterials. HDPE/TiO2 nanocomposites with varying TiO2 nanoparticles content were fabricated by using injection molding technique and were subjected to mechanical, thermal and biological characterization. SEM-EDS analysis confirmed even dispersion of TiO2 nanoparticles into the HDPE matrix. It was observed from the mechanical testing that the addition of TiO2 nanoparticles to HDPE noticeably improved the stiffness (from 345 to 378 MPa) while maintaining almost similar yield strength of pure HDPE. The thermal analyses revealed that TiO2 nanoparticles inclusion to HDPE matrix enhanced the thermal stability of nanocomposites, as the overall rate of crystallization increased by almost 4%. Furthermore, biocompatibility of nanocomposites was also studied by means of various cell culture experiments; human osteoblasts (hFOB) were seeded on the HDPE/TiO2 nanocomposites and were visualized through SEM after 72 h of incubation; surface morphology revealed normal cell growth and spreading with more attachment on PNC-10 that contains 10 wt.% of TiO2. Moreover, cell viability assays (i.e., MTT and cell attachment) revealed consistent increase in cell count and metabolic activity when triplicate cultures were incubated for 1, 3 and 7 days.

Post-consumer contamination in high-density polyethylene (HDPE) milk bottles and the design of a bottle-to-bottle recycling process.

Science.gov (United States)

Welle, F

2005-10-01

Six hundred conventional recycled HDPE flake samples, which were recollected and sorted in the UK, were screened for post-consumer contamination levels. Each analysed sample consisted of 40-50 individual flakes so that the amount of analysed individual containers was in the range 24,000-30,000 post-consumer milk bottles. Predominant contaminants in hot-washed flake samples were unsaturated oligomers, which can be also be found in virgin high-density polyethylene (HDPE) pellet samples used for milk bottle production. In addition, the flavour compound limonene, the degradation product of antioxidant additives di-tert-butylphenol and low amounts of saturated oligomers were found in higher concentrations in the post-consumer samples in comparison with virgin HDPE. However, the overall concentrations in post-consumer recycled samples were similar to or lower than concentration ranges in comparison with virgin HDPE. Contamination with other HDPE untypical compounds was rare and was in most cases related to non-milk bottles, which are HDPE and on the high cleaning efficiency of the super-clean recycling process especially for highly volatile compounds, the recycling process investigated is suitable for recycled post-consumer HDPE bottles for direct food-contact applications. However, hand-picking after automatically sorting is recommended to decrease the amount of non-milk bottles. The conclusions for suitability are valid, provided that the migration testing of recyclate contains milk bottles up to 100% and that both shelf-life testing and sensorial testing of the products are successful, which are topics of further investigations.

Effect of TiO2 Nanofiller Concentration on the Mechanical, Thermal and Biological Properties of HDPE/TiO2 Nanocomposites

Science.gov (United States)

Mozumder, Mohammad Sayem; Mourad, Abdel-Hamid I.; Mairpady, Anusha; Pervez, Hifsa; Haque, Md Emdadul

2018-03-01

The necessity for advanced and effective biomimetic tissue engineering materials has increased massively as bone diseases such as osteoporosis and bone cancer have become a major public health problem. Therefore, the objective of this study is to develop titanium dioxide (TiO2) nanoparticles-enriched high-density polyethylene (HDPE) nanocomposites that could serve as potential biomaterials. HDPE/TiO2 nanocomposites with varying TiO2 nanoparticles content were fabricated by using injection molding technique and were subjected to mechanical, thermal and biological characterization. SEM-EDS analysis confirmed even dispersion of TiO2 nanoparticles into the HDPE matrix. It was observed from the mechanical testing that the addition of TiO2 nanoparticles to HDPE noticeably improved the stiffness (from 345 to 378 MPa) while maintaining almost similar yield strength of pure HDPE. The thermal analyses revealed that TiO2 nanoparticles inclusion to HDPE matrix enhanced the thermal stability of nanocomposites, as the overall rate of crystallization increased by almost 4%. Furthermore, biocompatibility of nanocomposites was also studied by means of various cell culture experiments; human osteoblasts (hFOB) were seeded on the HDPE/TiO2 nanocomposites and were visualized through SEM after 72 h of incubation; surface morphology revealed normal cell growth and spreading with more attachment on PNC-10 that contains 10 wt.% of TiO2. Moreover, cell viability assays (i.e., MTT and cell attachment) revealed consistent increase in cell count and metabolic activity when triplicate cultures were incubated for 1, 3 and 7 days.

Application of glass particles doped by Zn{sup +2} as an antimicrobial and atoxic compound in LLDPE and HDPE

Energy Technology Data Exchange (ETDEWEB)

Santos, M.F. [Post-Graduate Program in Science and Materials Engineering, Universidade do Extremo Sul Catarianese/UNESC, Av. Universitária, 1105, CEP 88806-000, Criciúma, Santa Catarina (Brazil); Machado, C.; Tachinski, C.G.; Júnior, J.F.; Piletti, R. [Laboratory of Advanced Materials and Processes, Universidade do Extremo Sul Catarianese/UNESC, iParque, Rod. Gov. Jorge Lacerda, km 4,5, CEP 88806-000, Criciúma, SC (Brazil); Peterson, M. [Post-Graduate Program in Science and Materials Engineering, Universidade do Extremo Sul Catarianese/UNESC, Av. Universitária, 1105, CEP 88806-000, Criciúma, Santa Catarina (Brazil); Laboratory of Advanced Materials and Processes, Universidade do Extremo Sul Catarianese/UNESC, iParque, Rod. Gov. Jorge Lacerda, km 4,5, CEP 88806-000, Criciúma, SC (Brazil); Fiori, M.A., E-mail: fiori@unochapeco.edu.br [Post-Graduation Program in Environmental Science, Universidade Comunitária da Região de Chapecó (Unochapecó), Chapecó, SC (Brazil); Post-Graduation Program in Technology and Management of the Innovation, Universidade Comunitária da Região de Chapecó (Unochapecó), Chapecó, SC (Brazil)

2014-06-01

This study demonstrates the potential application of glass particles doped with Zn{sup +2} (GZn) as an atoxic, antimicrobial additive when used in conjunction with high density polyethylene (HDPE) and linear low density polyethylene (LLDPE) polymers. Toxicity tests demonstrated that these modified glass particles were nontoxic to human cells, and atomic absorption analyses demonstrated the migration of ionic species in quantities less than 2.0 ppm for both the HDPE/GZn and LLDPE/GZn compounds. Microbiological tests demonstrated the antimicrobial effect of the pure GZn compound as well as the polymeric HDPE/GZn and LLDPE/GZn compounds. In addition, at percentages of GZn higher than 2.00 wt.% and at a time of 4 h, the bactericidal performance is excellent and equal for both polymeric compounds. - Highlights: • Glass doped with Zn{sup +2} (GZn) promoted a good bactericidal properties in LLDPE and HDPE. • LLDPE and HDPE doped with GZn have capacity of liberty ionic zinc during a time period. • GZn is not toxic to human and can be used with antimicrobial additive to polymers. • GZn has an antimicrobial effect in bacteria type Gram positive and Gram negative.

Estudo da densidade óssea na esclerodermia sistêmica

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da Silva H.C.

1997-01-01

Full Text Available OBJETIVO. A osteopenia em pacientes com esclerodermia sistêmica foi descrita, radiologicamente, em mãos e, por densidade óssea, no terço proximal e distal do rádio. A redução da massa óssea, nesses pacientes, tem sido atribuída à isquemia, imobilização e à menopausa precoce. O objetivo deste estudo é analisar a densidade óssea na coluna, região proximal do fêmur e corpo todo de pacientes com esclerodermia sistêmica. PACIENTES E MÉTODO. Foram examinadas 25 pacientes caucasóides, sem outras condições que pudessem afetar o metabolismo ósseo. A média de idade das pacientes foi de 48 ± 12 anos, e o tempo de doença, de 7 ± 7 anos; 13 estavam na pós-menopausa há 8 ± 8 anos. A medida de massa óssea foi realizada na coluna, região proximal do fêmur e corpo todo, utilizando-se densitômetro de dupla emissão com fonte de raios X (Lunar - modelo DPX. RESULTADOS. Não houve diferença estatisticamente significante na densidade óssea das regiões avaliadas nas pacientes com esclerodermia sistêmica e as mulheres-controle pareadas para a idade, peso, altura e anos de menopausa. A densidade óssea das pacientes com forma limitada não foi diferente daquelas com a forma difusa. Pacientes com calcinose apresentaram menor densidade óssea na região proximal do fêmur que aquelas sem calcinose. CONCLUSÕES. Os autores concluíram que pacientes com esclerodermia sistêmica não apresentam perda de massa óssea. Portanto, a esclerodermia não é um fator de risco para o desenvolvimento de osteoporose generalizada.

HDPE/LLDPE blend-based nanocomposites - Part I: evaluation of thermo-mechanical properties and weathering resistance; Nanocompositos de blendas HDPE/LLDPE e OMMT - parte I: avaliacao das propriedades termo-mecanicas e da resistencia ao intemperismo

Energy Technology Data Exchange (ETDEWEB)

Passador, Fabio R.; Backes, Eduardo H.; Travain, Daniel R.; Ruvolo Filho, Adhemar; Pessan, Luiz A., E-mail: fabiopassador@gmail.com [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Engenharia de Materiais

2013-07-01

Nano composites from high density polyethylene/ linear low density polyethylene (HDPE/LLDPE) blends were prepared at the melt state in an extruder, using HDPE-g-MA as compatibilizer agent. The structural characterization was performed through wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). The results showed that adding the compatibilizer induced formation of a predominant intercalated microstructure. Dynamic-mechanical studies showed that the addition of the compatibilizer increases the interactions between the nano clay surface and the polyolefin matrix. The weathering conditions affected the mechanical behavior of HDPE/LLDPE blend-based nano composites. Both treatments performed in hot water and in a forced convection air oven provided the relief of residual stresses in the polymer matrix, while the treatment in an accelerated aging chamber provided the formation of carbonyl groups that lead to a decreased degree of crystallinity and elastic modulus of the nanocomposites. (author)

La densidad urbana como variable de análisis de la ciudad: El caso de Cuenca, Ecuador

Directory of Open Access Journals (Sweden)

M. Augusta Hermida

2015-09-01

Full Text Available El debate teórico sobre la ciudad dispersa versus la ciudad compacta, en el mundo y particularmente en América Latina, pone en la palestra los aspectos clave necesarios para proponer un nuevo modelo de ciudad, donde la calidad de vida de las presentes y futuras generaciones sea el punto focal de reflexión. A través del estudio del estado del arte sobre el tema se concluye que el regreso a la ciudad compacta es la alternativa para un posible desarrollo sustentable en las ciudades intermedias de América Latina. En el caso de Cuenca, se concentra el estudio en las densidades de la ciudad desde los años cincuenta hasta nuestros días. Sorprende comprobar que Cuenca fue una ciudad compacta con alta calidad de vida pero que, paulatinamente, se está expandiendo innecesariamente, con todos los problemas que ello implica.

HDPE/clay hybrids: the effect of clay modified with poly(diphenyl siloxanes) on thermal and rheological properties

Energy Technology Data Exchange (ETDEWEB)

Monasterio, Fernanda E.; Carrera, Maria C.; Erdmann, Eleonora; Destefanis, Hugo A., E-mail: ferelenakq@gmail.co [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Buenos Aires (Argentina). Inst. de Investigaciones para la Industria Quimica; Pita, Victor J.R.R.; Dias, Marcos L. [Universidade Federal do Rio de Janeiro (IMA/UFRJ), RJ (Brazil). Inst. de Macromoleculas Profa. Eloisa Mano

2009-07-01

Poly(diphenyl siloxanes) (PDPhS) were synthesized in presence of organophilic clay in order to modify its nano structure. Two silane monomers were used: dimethoxydiphenylsilane and dichlorodiphenylsilane. The following characterizations were performed for all clays: XRD, FTIR and TGA/DTG. These siloxane-modified clays were more hydrophobic and had enhanced thermal stability. Solvent extraction was carried out in the siloxane-modified clays and the PDPhS soluble fraction analyzed according the molecular weight via GPC. The presence of free and grafted oligomers on clay surface was identified. The modified clays were added to HDPE by melt processing to obtain HDPE/clay hybrids which exhibited marked differences in the rheological behavior when compared with neat HDPE. (author)

HDPE/clay hybrids: the effect of clay modified with poly(diphenyl siloxanes) on thermal and rheological properties

International Nuclear Information System (INIS)

Monasterio, Fernanda E.; Carrera, Maria C.; Erdmann, Eleonora; Destefanis, Hugo A.; Pita, Victor J.R.R.; Dias, Marcos L.

2009-01-01

Poly(diphenyl siloxanes) (PDPhS) were synthesized in presence of organophilic clay in order to modify its nano structure. Two silane monomers were used: dimethoxydiphenylsilane and dichlorodiphenylsilane. The following characterizations were performed for all clays: XRD, FTIR and TGA/DTG. These siloxane-modified clays were more hydrophobic and had enhanced thermal stability. Solvent extraction was carried out in the siloxane-modified clays and the PDPhS soluble fraction analyzed according the molecular weight via GPC. The presence of free and grafted oligomers on clay surface was identified. The modified clays were added to HDPE by melt processing to obtain HDPE/clay hybrids which exhibited marked differences in the rheological behavior when compared with neat HDPE. (author)

Riqueza e densidade de aves que nidificam em cavidades em plantações abandonadas de eucalipto

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Hugo de Siqueira Pereira

2015-05-01

Full Text Available Monoculturas de árvores, como as de espécies de eucalipto, têm substituído florestas naturais, impactando a fauna pela perda de habitat e recursos. Diversas espécies de aves necessitam de ocos em árvores para nidificar. A falta de recursos como cavidades formadas pela degradação da árvore ou locais apropriados para serem criadas cavidades leva a diminuição na abundância das populações destas espécies. Este trabalho tem o objetivo de comparar a riqueza e a densidade de aves que nidificam em ocos em áreas de plantação de eucalipto abandonadas com áreas de vegetação nativa em duas unidades de conservação em Minas Gerais. Em cada tipo de vegetação de cada reserva foram estabelecidos 25 pontos, nas quais foi utilizado o método de contagem por remoção para o levantamento das espécies de aves. A riqueza de espécies de aves de cada área foi estimada por Jackniffe e a densidade foi estimada através do método de máxima verossimilhança; modelos candidatos que poderiam influenciar a abundância das aves foram avaliados utilizando-se o Critério de Informação Akaike (AIC. Os resultados mostraram que a riqueza de espécies foi maior nas áreas de florestas nativas e que a densidade foi significantemente mais alta nas áreas de florestas nativas, e que o tipo de vegetação e a hora do dia influenciam na abundância e detecção das aves. Esses resultados indicam que as plantações de eucaliptos influenciam negativamente a comunidade de aves que nidificam em ocos, provavelmente por causa da falta de cavidades ou de sub-bosque. Plantações de eucaliptos normalmente não substituem as florestas nativas e seu uso deve ser controlado em áreas de conservação.

Morphology, rheology and electrical resistivity of PLLA/HDPE/CNT nanocomposites: Effect of maleic anhydride

Energy Technology Data Exchange (ETDEWEB)

Shao, Li-na; Chen, Jie; Dai, Jian; Chen, Hai-ming; Yang, Jing-hui [Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Wang, Yong, E-mail: yongwang1976@163.com [Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Zhang, Chao-liang [State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610041 (China)

2015-02-15

As a part of serial work about tuning the selective location of carbon nanotubes (CNTs) in immiscible polymer blends, this work reports the effects of component polarity and viscosity ratio between components on the selective location of CNTs and the resultant electrical resistivity of the nanocomposites. To achieve the research aim, maleic anhydride (MA) was grafted onto poly(L-lactide) (PLLA) main chain through a reactive compounding processing. After that, different contents of CNTs were incorporated into blends of high density polyethylene (HDPE) and PLLA (or PLLA-g-MA). The morphologies of the ternary nanocomposites and the selective location of CNTs in the nanocomposites were characterized using scanning electron microscope (SEM) and transmission electron microscope (TEM). The microstructure of nanocomposites and the dispersion of CNTs were further proved by rheological measurement. Finally, the electrical resistivity of nanocomposites containing different CNT contents was measured. The results showed that through increasing the polarity of PLLA and decreasing the melt viscosity, CNTs were kinetically trapped at the blend interface region. Consequently, largely decreased percolation threshold was achieved for the PLLA-g-MA/HDPE/CNT nanocomposites. The morphological changes as well as the rheological properties were also comparatively analyzed. - Highlights: • PLLA/HDPE/CNT and PLLA-g-MA/HDPE/CNT composites were prepared. • Different selective location states of CNTs were achieved in different composites. • Selectively located CNTs at the interface resulted in lower percolation threshold.

HDPE/LLDPE blend-based nanocomposites - Part I: evaluation of thermo-mechanical properties and weathering resistance

International Nuclear Information System (INIS)

Passador, Fabio R.; Backes, Eduardo H.; Travain, Daniel R.; Ruvolo Filho, Adhemar; Pessan, Luiz A.

2013-01-01

Nano composites from high density polyethylene/ linear low density polyethylene (HDPE/LLDPE) blends were prepared at the melt state in an extruder, using HDPE-g-MA as compatibilizer agent. The structural characterization was performed through wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). The results showed that adding the compatibilizer induced formation of a predominant intercalated microstructure. Dynamic-mechanical studies showed that the addition of the compatibilizer increases the interactions between the nano clay surface and the polyolefin matrix. The weathering conditions affected the mechanical behavior of HDPE/LLDPE blend-based nano composites. Both treatments performed in hot water and in a forced convection air oven provided the relief of residual stresses in the polymer matrix, while the treatment in an accelerated aging chamber provided the formation of carbonyl groups that lead to a decreased degree of crystallinity and elastic modulus of the nanocomposites. (author)

Rheological characterization of LDPE{sub Al} (low density polyethylene and aluminum) e HDPE (high density polyethylene); Caracterizacao das propriedades reologicas da mistura LDPE{sub Al} (polietileno de baixa densidade e aluminio) e HDPE (polietileno de alta densidade)

Energy Technology Data Exchange (ETDEWEB)

Santa Marinha, Ana Beatriz Abreu; Pacheco, Elen Beatriz Acordi Vasques; Monteiro, Elisabeth Ermel da Costa [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Macromoleculas

2008-07-01

The long life packaging contains paper, polyethylene and aluminum for packaging of food. A few part of total amount produced is recycled and another is discharged in landfills in Brazil. The low density polyethylene and aluminum (LDPE{sub Al}) was obtained from recycling this packaging. The rheological properties of the blends were intermediate to ones of the pure polymers. In a general way, the rheological properties were not modified by the aluminum presence. (author)

Efeito da adição de diferentes copolímeros em blendas HDPE/HIPS pós-consumo: morfologia de fases e propriedades térmicas The effect of different block copolymers on post consumer HDPE/HIPS Blends: phase morphology and thermal properties

Directory of Open Access Journals (Sweden)

Igor S. B. Perez

2008-09-01

Full Text Available Blendas de poliolefinas/HIPS têm sido exploradas para obter filmes especiais com determinadas propriedades desejadas, tornando imperativo desenvolver vários estudos para um melhor conhecimento do comportamento desses materiais. Neste trabalho, efeitos da adição dos copolímeros comerciais de estireno-butadieno multibloco (SBS e de estireno-(etileno-co-butileno-estireno (SEBS tribloco linear em blendas pós-consumo de HDPE e HIPS são reportados. A diminuição nas dimensões da microfase dispersa, aliada à rugosidade superficial da fase HDPE após extração seletiva do HIPS, independentemente de a fase matriz ser HIPS ou HDPE, mostraram mais eficiência do SEBS como modificador interfacial de tensão ou como surfactante entre os diferentes domínios quando comparado com o SBS. Os resultados das caracterizações térmicas, por exemplo, menor Tm e menor grau de cristalinidade do HDPE, e maior Tg do poliestireno na presença de SEBS corroboraram esta conclusão, como será discutido posteriormente.Blending of post-consumer polyolefins/HIPS has been exploited for obtaining special films with a desired set of properties, which has required studies to understand the behavior of these materials. In this work the effects of commercial multiblock styrene-butadiene (SBS and linear triblock styrene-(ethylene-co-butylene-styrene (SEBS copolymers in blends of post-consumer high density polyethylene (HDPE and HIPS are reported. Thermal properties and phase morphology were comparatively analyzed for the additives aiming at verifying possible correlations between them. Decreased dimensions of the minor micro phase along with HDPE surface roughness after HIPS selective extraction, independently of the matrix being HIPS or HDPE, showed better effectiveness for SEBS as interfacial tension modifier or as surfactant at the different domains interface when compared with SBS. The results of thermal characterizations, e.g. lower HDPE melting temperature, lower

ESR Study of PE, HDPE and UHMWPE Irradiated with Ion Beams and Neutrons

International Nuclear Information System (INIS)

Reyes-Romero, J.

2006-01-01

We report the Electron Spin Resonance (RES) studies on the effects produced by bombarding with accelerated Sulfur ions, Protons and Neutrons on the Polyethylene, PE, (Hostalen and Romanian), ultra-high molecular weight polyethylene, UHMWPE, ( GUR 1050, medical grade Lennite), and high density polyethylene, HDPE, (HDPE-7000F, Polinter de Venezuela, PDVSA). The resonance spectra have been recorded using a Varian E-line-X ESR spectrometer at 100 KHz modulation frequency. In thin films of Polyethylene (Hostalen and UHMWPE) have been irradiated with Sulfur ions, S, accelerated at about 7 MeV/nucleons, and Protons at about 5 MeV/nucleons (IFIN, Romania). Samples of Polyethylene ( HDPE 7000-F) were irradiate with neutrons from a Pu-Be source (flux of 1.19 x 10 6 n/s. cm 2 , 5.65 MeV, IVIC, Venezuela) from 0 to 8 hours in the presence of air and at room temperature (RT). The ESR measurements were performed after a storage time of about 7 months, in air at room temperature. The nature of the free radicals induced by irradiation as well as the dependence of resonance line, resonance line shape and radicals concentration has been studied

Diffusion of multiwall carbon nanotubes (MWCNTs) through a high density polyethylene (HDPE) geomembrane.

Science.gov (United States)

Saheli, P T; Rowe, R K; Petersen, E J; O'Carroll, D M

2017-05-01

The new applications for carbon nanotubes (CNTs) in various fields and consequently their greater production volume have increased their potential release to the environment. Landfills are one of the major locations where carbon nanotubes are expected to be disposed and it is important to ensure that they can limit the release of CNTs. Diffusion of multiwall carbon nanotubes (MWCNTs) dispersed in an aqueous media through a high-density polyethylene (HDPE) geomembrane (as a part of the landfill barrier system) was examined. Based on the laboratory tests, the permeation coefficient was estimated to be less than 5.1×10 -15 m 2 /s. The potential performance of a HDPE geomembrane and geosynthetic clay liner (GCL) as parts of a composite liner in containing MWCNTs was modelled for six different scenarios. The results suggest that the low value of permeation coefficient of an HDPE geomembrane makes it an effective diffusive barrier for MWCNTs and by keeping the geomembrane defects to minimum during the construction (e.g., number of holes and length of wrinkles) a composite liner commonly used in municipal solid waste landfills will effectively contain MWCNTs.

Compressive strength and initial water absorption rate for cement brick containing high-density polyethylene (HDPE) as a substitutional material for sand

Science.gov (United States)

Ali, Noorwirdawati; Din, Norhasmiza; Sheikh Khalid, Faisal; Shahidan, Shahiron; Radziah Abdullah, Siti; Samad, Abdul Aziz Abdul; Mohamad, Noridah

2017-11-01

The rapid growth of today’s construction sector requires high amount of building materials. Bricks, known to have solid properties and easy to handle, which leads to the variety of materials added or replaced in its mixture. In this study, high density polyethylene (HDPE) was selected as the substitute materials in the making of bricks. The reason behind the use of HDPE is because of its recyclable properties and the recycling process that do not emit hazardous gases to the atmosphere. Other than that, the use of HDPE will help reducing the source of pollution by avoiding the millions of accumulated plastic waste in the disposal sites. Furthermore, the material has high endurance level and is weatherproof. This study was carried out on experimenting the substitute materials in the mixture of cement bricks, a component of building materials which is normally manufactured using the mixture of cement, sand and water, following a certain ratios, and left dried to produce blocks of bricks. A series of three different percentages of HDPE were used, which were 2.5%, 3.0% and 3.5%. Tests were done on the bricks, to study its compressive strength and the initial water absorption rate. Both tests were conducted on the seventh and 28th day. Based on the results acquired, for compressive strength tests on the 28th day, the use of 2.5% of HDPE shown values of 12.6 N/mm2 while the use of 3.0% of HDPE shown values of 12.5 N/mm2. Onto the next percentage, 3.5% of HDPE shown values of 12.5 N/mm2.

Estabilidad de procesamiento de polímeros: índice de degradación en proceso

OpenAIRE

Andrés Felipe Rojas González; Laura María Aranzazu Ríos

2015-01-01

Se presentan los resultados del análisis de estabilidad en proceso para polietileno de alta densidad grado extrusión (PEAD-GE), polietileno de alta densidad grado inyección (PEAD-GI), polietileno de baja densidad (PEBD), poliácido láctico (PLA), policarbonato (PC), poliestireno (PS), polimetíl metacrilato (PMMA) y polipropileno (PP). Estos polímeros se reprocesaron en 5 ciclos de extrusión, inyección y extrusión/inyección. Cada polímero virgen y reprocesado se caracterizó respecto al índice d...

The Effect of Water Cement Ratio on Cement Brick Containing High Density Polyethylene (HDPE as Sand Replacement

Directory of Open Access Journals (Sweden)

Ali Noorwirdawati

2018-01-01

Full Text Available Waste disposal can contribute to the problem of environmental pollution. Most of the waste material is plastic based, because the nature of difficult of plastic degradable by itself. In order to overcome the problem, many study has been conducted on the reuse of plastic material into various field such as civil engineering and construction. In this study, municipal solid waste (MSW in the form of High Density Polyethylene (HDPE plastic was used to replace sand in cement sand brick production. The HDPE used in this study was obtained from a recycle factory at Nilai, Negeri Sembilan. 3% of HDPE replacement was applied in this study, with the cement-sand mix design of 1:6 and water-cement ratio 0.35, 0.40, 0.45 and 0.50 respectively. All specimens were tested for compressive strength and water absorption at 7 and 28 days. The density of the bricks was also recorded. The finding show that brick with 3% HDPE content and 0.45 of water-cement ratio at 28 days of age curing show the highest compressive strength, which is 19.5N/mm2 compared to the control specimen of 14.4 N/mm2.

Estudio de un oscilador de densidad mediante medidas de potencial eléctrico

OpenAIRE

Rincon,N.E.; Fajardo,F.

2006-01-01

Un oscilador de densidad u oscilador salino, es un sistema no lineal que presenta cambios alternantes del sentido de flujo en el tiempo, como efecto de las restricciones espaciales entre dos fluidos de diferente densidad. Los fluidos están en recipientes separados, los cuales están interconectados por medio de un tubo capilar vertical. En este trabajo se construye un oscilador de densidad para estudiar la influencia de la variación de algunos de sus parámetros sobre las oscilaciones en el sen...

Engineering cartilage substitute with a specific size and shape using porous high-density polyethylene (HDPE) as internal support.

Science.gov (United States)

Wu, Yujia; Zhu, Lie; Jiang, Hua; Liu, Wei; Liu, Yu; Cao, Yilin; Zhou, Guangdong

2010-04-01

Despite the great advances in cartilage engineering, constructing cartilage of large sizes and appropriate shapes remains a great challenge, owing to limits in thickness of regenerated cartilage and to inferior mechanical properties of scaffolds. This study introduces a pre-shaped polyglycolic acid (PGA)-coated porous high-density polyethylene (HDPE) scaffold to overcome these challenges. HDPE was carved into cylindrical rods and wrapped around by PGA fibres to form PGA-HDPE scaffolds. Porcine chondrocytes were seeded into the scaffolds and the constructs were cultured in vitro for 2 weeks before subcutaneous implantation into nude mice. Scaffolds made purely of PGA with the same size and shape were used as a control. After 8 weeks of implantation, the construct formed cartilage-like tissue and retained its pre-designed shape and size. In addition, the regenerated cartilage grew and completely surrounded the HDPE core, which made the entire cartilage substitute biocompatible to its implanted environment as native cartilage similarly does. By contrast, the shape and size of the constructs in the control group seriously deformed and obvious hollow cavity and necrotic tissue were observed in the inner region. These results demonstrate that the use of HDPE as the internal support of a biodegradable scaffold has the potential to circumvent the problems of limitations in size and shape, with promising implications for the development of engineered cartilage appropriate for clinical applications. Copyright 2009 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Sensory aspects and water quality impacts of chlorinated and chloraminated drinking water in contact with HDPE and cPVC pipe.

Science.gov (United States)

Heim, Timothy H; Dietrich, Andrea M

2007-02-01

Pipes constructed with high-density polyethylene (HDPE) or chlorinated polyvinyl chloride (cPVC) are commonly used in drinking water distribution systems and premise plumbing. In this comprehensive investigation, the effects on odor, organic chemical release, trihalomethane (THM) formation, free chlorine demand and monochloramine demand were determined for water exposed to HDPE and cPVC pipes. The study was conducted in accordance with the Utility Quick Test (UQT), a migration/leaching protocol for analysis of materials in contact with drinking water. The sensory panel consistently attributed a weak to moderate intensity of a "waxy/plastic/citrus" odor to the water from the HDPE pipes but not the cPVC-contacted water samples. The odor intensity generated by the HDPE pipe remained relatively constant for multiple water flushes, and the odor descriptors were affected by disinfectant type. Water samples stored in both types of pipe showed a significant increase in the leaching of organic compounds when compared to glass controls, with HDPE producing 0.14 microgTOC/cm(2) pipe surface, which was significantly greater than the TOC release from cPVC. Water stored in both types of pipe showed disinfectant demands of 0.1-0.9 microg disinfectant/cm(2) pipe surface, with HDPE exerting more demand than cPVC. No THMs were detected in chlorinated water exposed to the pipes. The results demonstrate the impact that synthetic plumbing materials can have on sensory and chemical water quality, as well as the significant variations in drinking water quality generated from different materials.

TransAlta: More than a utility

International Nuclear Information System (INIS)

Mikalson, D.A.

1991-01-01

TransAlta Utilities Corporation is Canada's largest privately owned utility and is also a major coal mining company. In 1989, TransAlta produced 20.9% of all coal mined in Canada. A brief history of TransAlta is presented along with TransAlta's present coal operations and plans for the next three years. An overview is presented of how TransAlta Fuel Supply is organized to utilize contracted mining operation, engineering and environmental services and in-house capabilities. Recent strategic initiatives to improve organizational efficiency and the mining operations are discussed. These range from developing a common departmental vision to modifying major mining equipment. TransAlta's proactive role in clean coal combustion such as low NOx-SOx burner, integrated combined cycle gasification, and other energy research projects is reviewed. A summary is provided of recent participation of TransAlta in environmental management initiatives. Recent successes of TransAlta's unregulated subsidiary in the development of cogeneration facilities and the future of this area of business are discussed. 8 refs., 4 figs

Oxygen plasma treatments of jute fibers in improving the mechanical properties of jute/HDPE composites

Energy Technology Data Exchange (ETDEWEB)

Sever, K. [Department of Mechanical Engineering, Dokuz Eylul University, 35100, Izmir (Turkey); Erden, S. [Department of Mechanical Engineering, Ege University, 35100, Izmir (Turkey); Guelec, H.A. [Department of Food Engineering, Yuzuncu Yil University, 65250, Van (Turkey); Seki, Y., E-mail: yoldas.seki@deu.edu.tr [Department of Chemistry, Dokuz Eylul University, 35160, Buca, Izmir (Turkey); Sarikanat, M. [Department of Mechanical Engineering, Ege University, 35100, Izmir (Turkey)

2011-09-15

Highlights: {yields} To improve mechanical properties of jute/HDPE composites, jute fabric was subjected to oxygen plasma treatment. {yields} LF and RF plasma systems at different plasma powers were used for treatment. {yields} In LF system, interlaminar shear strength, tensile and flexure strengths showed a tendency to increase at plasma powers of 30 and 60 W. - Abstract: The surfaces of jute fabrics have been oxygen plasma treated using low frequency (LF) and radio frequency (RF) plasma systems at different plasma powers (30, 60, and 90 W) for 15 min to improve the mechanical properties of jute fiber/HDPE (high density polyethylene) composites. The effect of oxygen plasma treatment on the functional groups of jute fibers was examined by X-ray photoelectron spectroscopy (XPS) analysis. Effects of oxygen plasma treatments on the mechanical properties of jute fiber/HDPE composites were investigated by means of tensile, flexure, and short-beam shear tests. Surface morphology of the fractured surfaces of composites was observed by using scanning electron microscopy (SEM). When RF plasma system was used, the interlaminar shear strength (ILSS) values of the composites increased with increasing plasma power. Similarly, in LF plasma system, ILSS values showed a tendency to increase at plasma powers of 30 and 60 W. However, increasing of plasma power to 90 W decreased the ILSS value of jute/HDPE composite. Also, tensile and flexure strengths of the composites showed similar trends.

Oxygen plasma treatments of jute fibers in improving the mechanical properties of jute/HDPE composites

International Nuclear Information System (INIS)

Sever, K.; Erden, S.; Guelec, H.A.; Seki, Y.; Sarikanat, M.

2011-01-01

Highlights: → To improve mechanical properties of jute/HDPE composites, jute fabric was subjected to oxygen plasma treatment. → LF and RF plasma systems at different plasma powers were used for treatment. → In LF system, interlaminar shear strength, tensile and flexure strengths showed a tendency to increase at plasma powers of 30 and 60 W. - Abstract: The surfaces of jute fabrics have been oxygen plasma treated using low frequency (LF) and radio frequency (RF) plasma systems at different plasma powers (30, 60, and 90 W) for 15 min to improve the mechanical properties of jute fiber/HDPE (high density polyethylene) composites. The effect of oxygen plasma treatment on the functional groups of jute fibers was examined by X-ray photoelectron spectroscopy (XPS) analysis. Effects of oxygen plasma treatments on the mechanical properties of jute fiber/HDPE composites were investigated by means of tensile, flexure, and short-beam shear tests. Surface morphology of the fractured surfaces of composites was observed by using scanning electron microscopy (SEM). When RF plasma system was used, the interlaminar shear strength (ILSS) values of the composites increased with increasing plasma power. Similarly, in LF plasma system, ILSS values showed a tendency to increase at plasma powers of 30 and 60 W. However, increasing of plasma power to 90 W decreased the ILSS value of jute/HDPE composite. Also, tensile and flexure strengths of the composites showed similar trends.

Parâmetros sangüíneos de pacu Piaractus mesopotamicus (Holmberg, 1887 alimentados com dietas suplementadas com cromo trivalente em duas densidades de estocagem = Hematological parameters of pacu Piaractus mesopotamicus (Holmberg, 1887 fed diets supplemented with trivalent chromium in two stocking densities

Directory of Open Access Journals (Sweden)

Rodrigo Yudi Fujimoto

2007-10-01

Full Text Available O objetivo deste trabalho foi avaliar os efeitos da suplementação com cromo trivalente (0, 6, 12 e 18 mg kg-1 de ração sobre as variáveis hematológicas de Piaractus mesopotamicus, mantidos em duas densidades de estocagem (4 e 20 kg m-3. Os mantidos na maior densidade e alimentados com dietas suplementadas com 0 e 6 mg de cromo kg-1apresentaram redução do número de linfócitos circulantes, sugerindo má adaptação a essa condição de alta densidade. Nas dietas suplementadas com 12 e 18 mg kg-1, tal efeito não foi observado, porém verificou-se aumento do número de trombócitos no tratamento com 12 mg de cromo kg-1. A inexistência de diferença significativa entre os tratamentos, aos 30 dias, sugere a adaptação dos peixes ao tipo de alimento e à situação de alta densidade. Portanto, nas condições deste ensaio, a suplementação com 12 e 18 mg de cromo kg-1 é interessante como estratégia alimentar durante 15 dias.This work evaluated the effects of chromium supplementation on thehematological parameters of Piaractus mesopotamicus Holmberg, 1887 maintained in two stocking densities. Fish were fed diets supplemented with 0, 6, 12 and 18 mg trivalent chromium kg-1 dry ration and maintained at 4 and 20 kg m-3. The fish under high stockingdensity and fed diets supplemented with 0 and 6 mg kg-1 showed reduction in the number lymphocytes, which suggests non-adaptation to this condition of high density. This was not observed in fish fed diets supplemented with 12 and 18 mg chromium kg-1, but an increasein the number of thrombocytes was evident. The lack of difference between treatments after 30 days may suggest a possible adaptation of fish to the situation. It can be added that supplementation with 12 and 18 mg chromium kg-1 is an interesting feeding strategy for aperiod of 15 days.

Hydrogen-rich gas production by continuous pyrolysis and in-line catalytic reforming of pine wood waste and HDPE mixtures

International Nuclear Information System (INIS)

Arregi, Aitor; Amutio, Maider; Lopez, Gartzen; Artetxe, Maite; Alvarez, Jon; Bilbao, Javier; Olazar, Martin

2017-01-01

Highlights: • Plastic co-feeding improves the flexibility of biomass pyrolysis-reforming strategy. • Hydrogen production is enhanced by increasing plastic content in the feed. • The joint valorization of biomass and plastics attenuates catalyst deactivation. • The amorphous coke derived from biomass is the main responsible for deactivation. - Abstract: The continuous pyrolysis-reforming of pine sawdust and high density polyethylene mixtures (25, 50 and 75 wt% HDPE) has been performed in a two-stage reaction system provided with a conical spouted bed reactor (CSBR) and a fluidized bed reactor. The influence HDPE co-feeding has on the conversion, yields and composition of the reforming outlet stream and catalyst deactivation has been studied at a reforming temperature of 700 °C, with a space time of 16.7 g_c_a_t min g_f_e_e_d_i_n_g"−"1 and a steam/(biomass + HDPE) mass ratio of 4, and a comparison has been made between these results and those recorded by feeding pine sawdust and HDPE separately. Co-feeding plastics enhances the hydrogen production, which increases from 10.9 g of H_2 per 100 g of feed (only pine sawdust in the feed) to 37.3 g of H_2 per 100 g of feed (only HDPE in the feed). Catalyst deactivation by coke is attenuated when HDPE is co-fed due to the lower content of oxygenated compounds in the reaction environment. The higher yield of hydrogen achieved with this two-step (pyrolysis-reforming) strategy, its ability to jointly valorise biomass and plastic mixtures and the lower temperatures required compared to gasification make this promising process for producing H_2 from renewable raw materials and wastes.

Application of glass particles doped by Zn(+2) as an antimicrobial and atoxic compound in LLDPE and HDPE.

Science.gov (United States)

Santos, M F; Machado, C; Tachinski, C G; Júnior, J F; Piletti, R; Peterson, M; Fiori, M A

2014-06-01

This study demonstrates the potential application of glass particles doped with Zn(+2) (GZn) as an atoxic, antimicrobial additive when used in conjunction with high density polyethylene (HDPE) and linear low density polyethylene (LLDPE) polymers. Toxicity tests demonstrated that these modified glass particles were nontoxic to human cells, and atomic absorption analyses demonstrated the migration of ionic species in quantities less than 2.0ppm for both the HDPE/GZn and LLDPE/GZn compounds. Microbiological tests demonstrated the antimicrobial effect of the pure GZn compound as well as the polymeric HDPE/GZn and LLDPE/GZn compounds. In addition, at percentages of GZn higher than 2.00wt.% and at a time of 4h, the bactericidal performance is excellent and equal for both polymeric compounds. Copyright © 2014 Elsevier B.V. All rights reserved.

Identificación de Tareas Isométricas y Dinámicas del Miembro Superior Basada en EMG de Alta Densidad

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Mónica Rojas- Martínez

2017-10-01

Full Text Available Resumen: La identificación de tareas y estimación del movimiento voluntario basados en electromiografía (EMG constituyen un problema conocido que involucra diferentes áreas en sistemas expertos, particularmente la de reconocimiento de patrones, con muchas aplicaciones posibles en dispositivos de asistencia y rehabilitación. La información que proporciona puede resultar útil para el control de exoesqueletos o brazos robóticos utilizados en terapias activas. La tecnología emergente de electromiografía de alta densidad (HD-EMG abre nuevas posibilidades para extraer información neural y ya ha sido reportado que la distribución espacial de mapas de intensidad HD-EMG es una característica valiosa en la identificación de tareas isométricas (contracciones que no producen cambio en la longitud del músculo. Este estudio explora la utilización de la distribución espacial de la actividad mioeléctrica y lleva a cabo identificación de tareas durante ejercicios dinámicos a diferentes velocidades que son mucho más cercanos a los que se utilizan habitualmente en las terapias de rehabilitación. Con este objetivo, se registraron señales HD-EMG en un grupo de sujetos sanos durante la realización de un conjunto de tareas isométricas y dinámicas del miembro superior. Los resultados indican que la distribución espacial es una característica muy útil en la identificación, no solo de contracciones isométricas sino también de contracciones dinámicas, mejorando la eficiencia y naturalidad del control de dispositivos de rehabilitación para que se adapte mejor al usuario. Abstract: Identification of tasks and estimation of volitional movement based on electromyography (EMG constitute a known problem that involves different areas in the field of expert systems and particularly pattern recognition, with many possible applications in assistive and rehabilitation devices. The obtained information can be very useful to control exoskeletons or

Variación de la densidad aparente en órdenes de suelos de Costa Rica

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Alfredo Alvarado

2005-01-01

Full Text Available Este estudio se basa en la información de densidad aparente de 111 perfiles de suelos, representativos de los principales órdenes de suelo descritos por varios autores en Costa Rica. El ámbito de variación de la densidad aparente en los suelos estudiados es alto y osciló entre 0,53 y 2,00 Mg m-3. En general, los valores tendieron a aumentar con la profundidad del suelo debido a la reducción de la actividad biológica desarrollada en el horizonte A. Cuando no se encuentran capas compactadas, el horizonte enriquecido con arcilla eluviada (B2t de Ultisoles y Alfisoles presenta un incremento de la densidad aparente. Los valores bajos de densidad aparente en Andisoles se relacionan con el origen del material parental y en el caso de los Vertisoles con la densidad de partículas de la fracción esmectítica dominante.

LENRA as compatibilizer in NR/HDPE blends

International Nuclear Information System (INIS)

Mahathir Mohamed; Dahlan Mohd

2004-01-01

Polymer blends of 60/40 NR/HDPE were prepared using Brabender PL2000 plasticorder with 60g capacity. The blends were added with radiation sensitive natural rubber (NR)-based compatibilizer, known as LENRA. They were irradiated in air with electron beam radiation at various doses. The efficacy of the compatibilizer was monitored by measuring various properties of the blends such as physical and dynamic mechanical properties including morphological studies by electron microscopic technique. Early results show that the addition of LENRA improves the properties of the TPNR blends. (Author)

Effect of processing method on the mechanical and thermal of Silvergrass/HDPE composites

Science.gov (United States)

Liu, Bing; Jin, Yueqiang; Wang, Shuying

2017-05-01

This paper investigates the effect of compression and injection molding methods on properties of Silvergrass-HDPE (High Density Polyethylene) composites, with respect to mechanical behaviors. Maleated polyethylene (MAPE) was added in the composite and improved the mechanical property of the composite. The research founds MAPE can improve the mechanical property because it improved the interfacial compatibility as a coupling agent. When added a content of 8% of MAPE, Silvergrass-HDPE composites made from compression molding shows a better mechanical performance in tensile strength and flexural strength than that made from injection molding, with increasing Silvergrass fiber content from 30% to 50%. However, the WPCs (wood plastics composites) made from injection molding had a lower degree of crystallinity with or without MAPE treatment.

Impacto del CO2 sobre la densidad celular en seis cepas de microalgas marinas

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Alberto I. Oscanoa Huaynate

2015-12-01

Full Text Available Debido a la gran facilidad con que las microalgas pueden capturar el CO2 del medio ambiente, resulta interesante evaluar la cantidad y tiempo de ingreso de éste a los cultivos masivos, con la fi nalidad de aumentar la densidad celular. El objetivo del presente estudio fue evaluar los tiempos de inyección del mencionado gas, durante la producción de biomasa que conlleve a una mayor densidad celular, evaluando además, la variación del pH sin alterar la calidad del cultivo. A partir de seis cepas obtenidas del Banco de Germoplasma del Instituto del Mar del Perú, se realizaron cultivos tipo batch de 300L en invernadero, el tiempo de cultivo de la fase exponencial donde se realizaron las pruebas fue de tres días. Los datos se procesaron mediante el análisis del parámetro pendiente de la regresión lineal. Los resultados mostraron que la densidad celular es inversamente proporcional al tiempo de inyección de CO2 al cultivo. La mayor densidad celular, en las diferentes cepas, se obtuvo a los 5min, excepto para las cepas Chaetoceros gracilisy Nannochloris maculata, las cuales obtienen la mayor densidad a los 10 y 15min, respectivamente. La variación de pH tendió hacia la acidez, en un rango de 8 a 4, sin alterar la densidad celular, por el contrario, los cultivos permanecieron libres de contaminantes. En conclusión, los resultados permiten establecer tiempos adecuados de inyección del CO2, los cuales fortalecen la fase de crecimiento exponencial aumentando la densidad poblacional en un 30% sobre lo establecido en esta fase.

Effect of titanium dioxide (TiO2) on largely improving solar reflectance and cooling property of high density polyethylene (HDPE) by influencing its crystallization behavior

International Nuclear Information System (INIS)

Wang, Shichao; Zhang, Jun

2014-01-01

Highlights: • HDPE/TiO 2 composites have more perfect crystal structure. • Refractive index is the key factor affecting the final solar reflectance. • HDPE/TiO 2 composites can achieve high solar reflectance. • The real cooling property is in accordance with solar reflectance. - Abstract: In this study, the different crystal forms of titanium dioxide (TiO 2 ) were added into high density polyethylene (HDPE) to fabricate cool material. Crystal structure, crystallization behavior, crystal morphology were investigated by wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and polarized optical microscope (POM). Scanning electron microscope (SEM) was applied to observe dispersion of TiO 2 particles in the HDPE matrix and the cross section morphology. The solar reflectance and actual cooling property were evaluated by UV–Vis–NIR spectrometer and a self-designed device. By adding TiO 2 particles into HDPE matrix, the polymer chain could crystallize into more perfect and thermal stable lamella. The presence of TiO 2 particles dramatically increased the number of nucleation site therefore decreased the crystal size. The subsequent solar reflectance was related to the degree of crystallinity, the spherulite size of HDPE, refractive index, and distribution of TiO 2 particles in HDPE matrix. It was found the rutile TiO 2 could largely improve the total solar reflectance from 28.2% to 51.1%. Finally, the temperature test showed that the composites had excellent cooling property, which was in accordance with solar reflectance result

Compression Molding of Composite of Recycled HDPE and Recycled Tire Particles

Science.gov (United States)

Liu, Ping; Waskom, Tommy L.; Chen, Zhengyu; Li, Yanze; Peng, Linda

1996-01-01

Plastic and rubber recycling is an effective means of reducing solid waste to the environment and preserving natural resources. A project aimed at developing a new composite material from recycled high density polyethylene (HDPE) and recycled rubber is currently being conducted at Eastern Illinois University. The recycled plastic pellets with recycled rubber particles are extruded into some HDPE/rubber composite strands. The strand can be further cut into pellets that can be used to fabricate other material forms or products. This experiment was inspired by the above-mentioned research activity. In order to measure Durometer hardness of the extruded composite, a specimen with relatively large dimensions was needed. Thus, compression molding was used to form a cylindrical specimen of 1 in. diameter and 1 in. thickness. The initial poor quality of the molded specimen prompted a need to optimize the processing parameters such as temperature, holding time, and pressure. Design of experiment (DOE) was used to obtain optimum combination of the parameters.

Morphology, mechanical and thermal oxidative aging properties of HDPE composites reinforced by nonmetals recycled from waste printed circuit boards.

Science.gov (United States)

Yang, Shuangqiao; Bai, Shibing; Wang, Qi

2016-11-01

In this study nonmetals recycled from waste printed circuit boards (NPCB) is used as reinforce fillers in high-density polyethylene (HDPE) composites. The morphology, mechanical and thermal oxidative aging properties of NPCB reinforced HDPE composites are assessed and it compared with two other commercial functional filler for the first time. Mechanical test results showed that NPCB could be used as reinforcing fillers in the HDPE composites and mechanical properties especially for stiffness is better than other two commercial fillers. The improved mechanical property was confirmed by the higher aspect ratio and strong interfacial adhesion in scanning electron microscopy (SEM) studies. The heat deflection temperature (HDT) test showed the presence of fiberglass in NPCB can improve the heat resistance of composite for their potential applications. Meanwhile, the oxidation induction time (OIT) and the Fourier transform infrared (FTIR) spectroscopy results showed that NPCB has a near resistance to oxidation as two other commercial fillers used in this paper. The above results show the reuse of NPCB in the HDPE composites represents a promising way for resolving both the environmental pollution and the high-value reuse of resources. Copyright © 2015. Published by Elsevier Ltd.

Estonia's Alta buys Lauma lingerie

Index Scriptorium Estoniae

2004-01-01

Eesti investeeringute firma Alta Capital ostis 76,4 protsenti pesutootja Lauma aktsiatest. Tulevikus plaanitakse suunduda Ida- ja Lääne-Euroopa turgudele. Alta Capital omab 79 protsenti Klementi aktsiatest

Effect of ionizing radiation exposure in the morphology of modified HDPE with amphiphilic particles

International Nuclear Information System (INIS)

Saldanha, Ana Luiza M.; Vivas, Viviane; Zylberberg, Marcel P.; Silva, Tamara I.; Cardoso, Andre Luis V.; Pereira, Iaci M.; Patricio, Patricia S.O.

2015-01-01

One of the techniques used to improve the properties of high performance polymers is the addition of hybrid particles in the polymer. In this context, amphiphilic particles were synthesized in order to provide surface characteristics that enhance the interaction of the interface with the polymeric matrix of high density polyethylene (HDPE). The amphiphilic particles were added to matrix of HDPE and the modified polymer composites were exposed to ionizing radiation (x-rays) for different times. The changes caused by exposure to ionizing radiation in the composite morphology was observed through the small angle x-ray technique. The results suggest that the addition of amphiphilic particles increased the stability of the composite to degradation by radiation. (author)

MEASUREMENT AND MODELLING OF SORPTION EQUILIBRIUM CURVE OF WATER ON PA6, PP, HDPE AND PVC BY USING FLORY-HUGGINS MODEL

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Suherman Suherman

2012-02-01

Full Text Available The sorption of water on granular polyamide-6 (PA6, granular polypropylene (PP, and powdery high density polyethylene (HDPE and powdery polyvinyl chloride (PVC were measured using a gravimetric method in a magnetic suspension balance (MSB. The Flory-Huggins model was successfully applied on the sorption equilibrium curve of all investigated polymers. The influence of temperature is low. The value of Flory-Huggins parameters(c of PA6, PVC, PP and HDPE were 1.8, 5.8, 6.3, and 8.1, respectively. The water in PA6 is mainly bound moisture, while in PP, HDPE and PVC it is mainly surface moisture.

Preparation and Characterization of HDPE/EVA Flat Sheet Membranes by Thermally Induced Phase Separation Method

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Zahra Shoeyb

2015-06-01

Full Text Available The adjustment of material composition in fabrication of modified polymeric membrane has been considered the most efficient and easiest method. For this purpose blended membranes of high density polyethylene (HDPE–ethylene vinyl acetate (EVA were prepared by thermally induced phase separation method. The impact of EVA in the presence of diluent on the crystalization temperature was assessed using differential scanning calorimetry (DSC. The obtained results showed that EVA has no significant effect on the crystalization temperature of HDPE. The absorption frequencies at 1248 and 1749 cm-1, respectively, due to C-O and C=O streching vibrations of EVA functional groups, confirmed the existence of EVA in HDPE membrane. The pure water permeability of HDPE/EVA blend was measured and compared with that of neat HDPE membrane. The results showed that an EVA content up to 2.5 wt% raised water permeability considerably and the leafy structure of the membranes contracted and the pure water permeation dropped with higher EVA content. The results of porosity measurement and scanning electronic microscopic (SEM analysis also confirmed these findings. Contact angel measurements and atomic force microscopy (AFM examinations and static absorption of collagen protein on the membrane surfaces revealed that EVA content up to 5 wt% lowered the hydrophobicity of the membrane. By EVA content above 10 wt%, due to the structural alteration on the membrane surface, the contact angel and the collagen absorption on the surface of membrane increased. The measurement of tensile strength showed that with increasing EVA content the mechanical properties of the membranes improved due to interactions of polar groups in EVA.

High-density polyethylene (HDPE)-degrading potential bacteria from marine ecosystem of Gulf of Mannar, India.

Science.gov (United States)

Balasubramanian, V; Natarajan, K; Hemambika, B; Ramesh, N; Sumathi, C S; Kottaimuthu, R; Rajesh Kannan, V

2010-08-01

Assessment of high-density polyethylene (HDPE)-degrading bacteria isolated from plastic waste dumpsites of Gulf of Mannar. Rationally, 15 bacteria (GMB1-GMB15) were isolated by enrichment technique. GMB5 and GMB7 were selected for further studies based on their efficiency to degrade the HDPE and identified as Arthrobacter sp. and Pseudomonas sp., respectively. Assessed weight loss of HDPE after 30 days of incubation was nearly 12% for Arthrobacter sp. and 15% for Pseudomonas sp. The bacterial adhesion to hydrocarbon (BATH) assay showed that the cell surface hydrophobicity of Pseudomonas sp. was higher than Arthrobacter sp. Both fluorescein diacetate hydrolysis and protein content of the biofilm were used to test the viability and protein density of the biomass. Acute peak elevation was observed between 2 and 5 days of inoculation for both bacteria. Fourier transform infrared (FT-IR) spectrum showed that keto carbonyl bond index (KCBI), Ester carbonyl bond index (ECBI) and Vinyl bond index (VBI) were increased indicating changes in functional group(s) and/or side chain modification confirming the biodegradation. The results pose us to suggest that both Pseudomonas sp. and Arthrobacter sp. were proven efficient to degrade HDPE, albeit the former was more efficacious, yet the ability of latter cannot be neglected. Recent alarm on ecological threats to marine system is dumping plastic waste in the marine ecosystem and coastal arena by anthropogenic activity. In maintenance phase of the plastic-derived polyethylene waste, the microbial degradation plays a major role; the information accomplished in this work will be the initiating point for the degradation of polyethylene by indigenous bacterial population in the marine ecosystem and provides a novel eco-friendly solution in eco-management.

Desenvolvimento e produção da bananeira 'grande naine' sob diferentes densidades de plantio em região com ocorrência natural de sigatoka-negra

Directory of Open Access Journals (Sweden)

Edson Shigueaki Nomura

2013-06-01

Full Text Available A alta densidade de plantio de algumas cultivares de bananeira é uma prática utilizável para aumentar a produtividade, sobretudo em regiões afetadas pela Sigatoka. Este trabalho objetivou avaliar o desenvolvimento e a produção de bananeiras 'Grande Naine' cultivadas em diferentes densidades de plantio para a convivência com a Sigatoka-Negra no Vale do Ribeira-SP. Para isso, foi instalado pomar de bananeiras produzidas in vitro da 'Grande Naine', em delineamento inteiramente ao acaso, em esquema fatorial 5 x 2, sendo cinco densidades (2.500; 2.222; 2.000; 1.667 e 1.111 plantas.ha-1 e dois ciclos de produção. A severidade da Sigatoka-Negra foi monitorada semanalmente, utilizando o método de Estado da Evolução (EE e para o seu controle foram definidas pela segunda progressão consecutiva da severidade e/ou aumento superior a 200 pontos de uma semana para a outra. De cada parcela, oito plantas foram avaliadas quanto à altura, diâmetro do pseudocaule, número de folhas ativas no florescimento e na colheita, massa fresca dos frutos comercializáveis, produtividade, número de pencas e frutos no cacho, massa fresca total e por frutos da 2ª penca, comprimento e diâmetro de frutos da 2ª penca. Os dados foram submetidos à análise de variância pelo teste F, e as médias, quando significativas, foram comparadas pelo teste de Tukey (5% de probabilidade. Diante das condições experimentais, conclui-se que o adensamento não influenciou no desenvolvimento em altura da planta e no diâmetro do pseudocaule de bananeira 'Grande Naine'. O adensamento de plantas proporcionou maiores produtividades de bananeira 'Grande Naine' nas condições do Vale do Ribera-SP.

Morphology and properties of SEBS block copolymer compatibilized PS/HDPE blends

Czech Academy of Sciences Publication Activity Database

Rek, V.; Vranješ, N.; Šlouf, Miroslav; Fortelný, Ivan; Jelčic, Ž.

2008-01-01

Roč. 40, č. 3 (2008), s. 237-251 ISSN 0095-2443 Grant - others:Ministry of Science, Education and Sport (HR) 0125059 Institutional research plan: CEZ:AV0Z40500505 Keywords : aPS/HDPE/SEBS blends * morphology * processing * rheological Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.658, year: 2008

Pengaruh Konsentrasi Maleat Anhidrat Terhadap Derajat Grafting Maleat Anhidrat Pada High Density Polyethylene ( HDPE ) Dengan Inisiator Benzoil Peroksida

OpenAIRE

Iwan Pranata Sitepu

2009-01-01

Telah dilakukan penelitian tentang pengaruh konsentrasi maleat anhidrat terhadap derajat grafting maleat anhidrat pada High Density Polyethylene ( HDPE ) dengan inisiator Benzoil Peroksida, dilakukan dengan teknik pengolahan reaktif dalam Internal Mixer pada suhu 1450C dan waktu proses selama 60 menit dengan variasi komposisi HDPE:MA:BPO, 95:3:2, 92:6:2, 89:9:2, 86:12:2 dan 83:15:2. Selanjutnya dilakukan penentuan derajat grafting dengan metode titrasi dan analisis spektra FTIR untuk menen...

Partitioning and diffusion of PBDEs through an HDPE geomembrane.

Science.gov (United States)

Rowe, R Kerry; Saheli, Pooneh T; Rutter, Allison

2016-09-01

Polybrominated diphenyl ether (PBDE) has been measured in MSW landfill leachate and its migration through a modern landfill liner has not been investigated previously. To assure environmental protection, it is important to evaluate the efficacy of landfill liners for controlling the release of PBDE to the environment to a negligible level. The partitioning and diffusion of a commercial mixture of PBDEs (DE-71: predominantly containing six congeners) with respect to a high-density polyethylene (HDPE) geomembrane is examined. The results show that the partitioning coefficients of the six congeners in this mixture range from 700,000 to 7,500,000 and the diffusion coefficients range from 1.3 to 6.0×10(-15)m(2)/s depending on the congener. This combination of very high partitioning coefficients and very low diffusion coefficients suggest that a well constructed HDPE geomembrane liner will be an extremely effective barrier for PBDEs with respect to diffusion from a municipal solid waste landfill, as illustrated by an example. The results for pure diffusion scenario showed that the congeners investigated meet the guidelines by at least a factor of three for an effective geomembrane liner where diffusion is the controlling transport mechanism. Copyright © 2016 Elsevier Ltd. All rights reserved.

Structural Studies of dielectric HDPE+ZrO2 polymer nanocomposites: filler concentration dependences

Science.gov (United States)

Nabiyev, A. A.; Islamov, A. Kh; Maharramov, A. M.; Nuriyev, M. A.; Ismayilova, R. S.; Doroshkevic, A. S.; Pawlukojc, A.; Turchenko, V. A.; Olejniczak, A.; Rulev, M. İ.; Almasan, V.; Kuklin, A. I.

2018-03-01

Structural properties of HDPE+ZrO2 polymer nanocomposites thin films of 80-100μm thicknesses were investigated using SANS, XRD, Laser Raman and FTIR spectroscopy. The mass fraction of the filler was 1, 3, 10, and 20%. Results of XRD analysis showed that ZrO2 powder was crystallized both in monoclinic and in cubic phase under normal conditions. The percentages of monoclinic and cubic phase were found to be 99.8% and 0.2%, respectively. It was found that ZrO2 nanoparticles did not affect the main crystal and chemical structure of HDPE, but the degree of crystallinity of the polymer decreases with increasing concentration of zirconium oxide. SANS experiments showed that at ambient conditions ZrO2 nanoparticles mainly distributed like mono-particles in the polymer matrix at all concentrations of filler.The structure of HDPE+ZrO2 does not changes up to 132°C at 1-3% of filler, excepting changing of the polymer structure at temperatures upper 82°C. At high concentrations of filler 10-20% the aggregation of ZrO2 nanoparticles occurs, forming domains of 2.5μm. The results of Raman and FTIR spectroscopy did not show additional specific chemical bonds between the filler and the polymer matrix. New peaks formation was not observed. These results suggest that core-shell structure does not exist in the polymer nanocomposite system.

Densidad de la madera de Pinus ponderosa (Dougl. Ex Laws) en tres localidades de Argentina

OpenAIRE

JOVANOVSKI, A; JARAMILLO, M; LOGUERCIO, G; ANTEQUERA, S

2002-01-01

Se estudió el ancho de anillo, la densidad básica de la madera y su variación y la relación entre ancho de anillo y densidad en Pinus ponderosa (Dougl. Ex. Laws) creciendo en tres localidades de la Patagonia andina argentina. El ancho de anillo obtenido se corresponde con una conífera de rápido crecimiento, mientras que la densidad media es levemente menor que la de la especie creciendo en los sitios de origen en Estados Unidos. Ring-width growth, wood specific gravity and its variation, a...

Effect of titanium dioxide (TiO{sub 2}) on largely improving solar reflectance and cooling property of high density polyethylene (HDPE) by influencing its crystallization behavior

Energy Technology Data Exchange (ETDEWEB)

Wang, Shichao; Zhang, Jun, E-mail: zhangjun@njtech.edu.cn

2014-12-25

Highlights: • HDPE/TiO{sub 2} composites have more perfect crystal structure. • Refractive index is the key factor affecting the final solar reflectance. • HDPE/TiO{sub 2} composites can achieve high solar reflectance. • The real cooling property is in accordance with solar reflectance. - Abstract: In this study, the different crystal forms of titanium dioxide (TiO{sub 2}) were added into high density polyethylene (HDPE) to fabricate cool material. Crystal structure, crystallization behavior, crystal morphology were investigated by wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and polarized optical microscope (POM). Scanning electron microscope (SEM) was applied to observe dispersion of TiO{sub 2} particles in the HDPE matrix and the cross section morphology. The solar reflectance and actual cooling property were evaluated by UV–Vis–NIR spectrometer and a self-designed device. By adding TiO{sub 2} particles into HDPE matrix, the polymer chain could crystallize into more perfect and thermal stable lamella. The presence of TiO{sub 2} particles dramatically increased the number of nucleation site therefore decreased the crystal size. The subsequent solar reflectance was related to the degree of crystallinity, the spherulite size of HDPE, refractive index, and distribution of TiO{sub 2} particles in HDPE matrix. It was found the rutile TiO{sub 2} could largely improve the total solar reflectance from 28.2% to 51.1%. Finally, the temperature test showed that the composites had excellent cooling property, which was in accordance with solar reflectance result.

A densidade básica e característica anatômicas variam radialmente na madeira de Astronium graveolens Jacq. (Anacardiaceae. Basic density and anatomical features vary in the radial direction in the wood of Astronium graveolens Jacq. (Anacardiaceae.

Directory of Open Access Journals (Sweden)

Camila Moura SANTOS

2011-12-01

Full Text Available Estudos sobre variações nas dimensões celulares de espécies arbóreas de clima tropical são escassos. Sendo assim, o objetivo deste trabalho foi caracterizar a variação da densidade básica e da anatomia no sentido radial da madeira de Astronium graveolens Jacq. Coletaram-se cinco indivíduos da espécie, provenientes da Estação Experimental Luiz Antônio (SP. Os métodos empregados nas análises foram os usualmente utilizados em pesquisas de densidade e anatomia de madeira. De acordo com os resultados foram constatadas altas correlações entre densidade básica, comprimento de fibra, espessura da parede da fibra, diâmetro de vaso e frequência de vaso com a distância da medula. A densidade básica da madeira é altamente dependente do comprimento das fibras, espessura da parede das fibras e diâmetro dos vasos, ocorrendo aumento no sentido da medula para a casca.Studies on variations in cell sizes of tree species in tropical climate are scarce. Thus, the aim was characterize the radial variation of basic density and wood anatomy of Astronium graveolens Jacq. Five specimens were collected at the Luiz Antônio Experimental Station,(SP. Sstandard methods for studying the density and wood anatomy were employed. According to the results we observed high correlation among basic density,fiber length, fiber wall thickness, vessel diameter and vessel frequency with distance fromthe pith. The wood density is highly dependent on fiber length, fiber wall thicknessand vessel diameter, there was an increase towards the pith to bark.

Friction and wear properties of novel HDPE--HAp--Al2O3 biocomposites against alumina counterface.

Science.gov (United States)

Bodhak, Subhadip; Nath, Shekhar; Basu, Bikramjit

2009-03-01

In an effort to enhance physical properties of biopolymers (high-density polyethylene, HDPE) in terms of elastic modulus and hardness, various ceramic fillers, like alumina (Al2O3) and hydroxyapatite (HAp) are added, and therefore it is essential to assess the friction and wear resistance properties of HDPE biocomposites. In this perspective, HDPE composites with varying ceramic filler content (upto 40 vol%) were fabricated under the optimal compression molding conditions and their friction and wear properties were evaluated against Al2O3 at fretting contacts. All the experiments were conducted at a load of 10 N for duration of 100,000 cycles in both dry as well as simulated body fluid (SBF). Such planned set of experiments has been designed to address three important issues: (a) whether the improvement in physical properties (hardness, E-modulus) will lead to corresponding improvement in friction and wear properties; (b) whether the fretting in SBF will provide sufficient lubrication in order to considerably enhance the tribological properties, as compared to that in ambient conditions; and (c) whether the generation of wear debris particles be reduced for various compositionally modified polymer composites, in comparison to unreinforced HDPE. The experimental results indicate the possibility of achieving extremely low coefficient of friction (COF approximately 0.047) as well as higher wear resistance (wear rate in the order of approximately 10(-7) mm3 N(-1) m(-1)) with the newly developed composites in SBF. A low wear depth of 3.5-4 microm is recorded, irrespective of fretting environment. Much effort has been put forward to correlate the friction and wear mechanisms with abrasion, adhesion, and wear debris formation.

Preparação e caracterização de biocompósitos baseados em fibra de curauá, biopolietileno de alta densidade (BPEAD e polibutadieno líquido hidroxilado (PBHL Preparation and characterization of biocomposites based on curaua fibers, high-density biopolyethylene (HDBPE and liquid hydroxylated polybutadiene(LHPB

Directory of Open Access Journals (Sweden)

Daniele O. Castro

2013-01-01

Full Text Available Neste trabalho, foram utilizadas fibras de curauá como reforço de matriz termoplástica de biopolietileno de alta densidade. O polietileno foi obtido por polimerização de eteno, gerado do etanol de cana de açúcar. Este polímero é também chamado de biopolietileno (BPEAD, por ser preparado a partir de material oriundo de fonte natural. Desta forma, pretendeu-se contribuir para desenvolver materiais que, dentre outras propriedades, causem menor emissão de CO2 para a atmosfera na sua produção, utilização e substituição, comparativamente a outros materiais. Adicionalmente, polibutadieno líquido hidroxilado (PBHL foi acrescentado à formulação do compósito, visando a um aumento na resistência à propagação da trinca durante impacto. Os compósitos e as fibras foram caracterizados por várias técnicas, tais como microscopia eletrônica de varredura (MEV, Calorimetria Exploratória Diferencial (DSC, Termogravimetria (TG, além da caracterização dos compósitos quanto à Análise Térmica Dinâmico-Mecânica (DMTA, propriedades mecânicas (impacto e flexão e absorção de água. A presença das fibras de curauá diminuiu algumas propriedades do BPEAD, como resistência ao impacto. A análise de DMTA mostrou que as fibras geram material mais rígido. Pode-se considerar que a introdução de PBHL na formulação do material foi eficiente, levando a uma resistência ao impacto do compósito BPEAD/PBHL/Fibra maior do que a do compósito BPEAD/Fibra.In this work, curaua fibers were used in the reinforcement of a high-density (HDPE thermoplastic matrix. The polyethylene used was obtained by polymerization of ethene produced from sugarcane ethanol. This polymer, also called high-density biopolyethylene (HDBPE, was prepared from a natural source material. The aim was to contribute to developing materials which could lead to smaller release of CO2 into the atmosphere in comparison to other materials. Additionally, liquid

Efeito do bebedouro e da densidade no desempenho de frangos alojados em alta temperatura Effect of type of water facility and density on performance of broiler reared in hot-climate

Directory of Open Access Journals (Sweden)

José H.V. Silva

2005-12-01

Full Text Available Com o objetivo de avaliar o efeito do bebedouro pendular (BP e do bebedouro alternativo (BALT, e de diferentes densidades (10 e 14 aves m-2 sobre o desempenho de 240 frangos de corte de 12 a 18, 19 a 38 e de 39 a 46 dias de idade, realizou-se este experimento em condições de temperatura média de 27,6 ºC e umidade relativa de 70,4%, no qual foi utilizado um delineamento inteiramente casualizado em esquema fatorial 2 x 2 (dois bebedouros x duas densidades, resultando em quatro tratamentos constituídos de cinco repetições de 10 aves. O BALT foi desenvolvido com base no conceito de amplo espaço de calha circular e alta profundidade de lâmina de água (5 cm para permitir a imersão do bico e das faces da ave. Na alimentação das aves, foram utilizadas rações comerciais, cujo consumo (CR caiu, enquanto a conversão alimentar (CA melhorou, quando o BALT foi empregado de 12 a 18 dias. Não houve efeito do bebedouro sobre o CR, ganho de peso (GP e CA no período total. A D14 (14 aves m-2 afetou o GP e o CR de 19 a 38 e de 39 a 46 dias e também no período total, mas a CA não foi alterada. O BALT não afeta o desempenho de frangos de corte, podendo ser usado como opção de baixo custo ao BP. A análise econômica pelo índice de rentabilidade relativa mostrou que o BALT e a D14 oferecem 1 e 5,9% de retorno a mais que o BP e a D10, (10 aves m-2 respectivamente.The experiment was undertaken in conditions of average temperature of 27.6 ºC and relative humidity of 70.4%, with the objective to evaluate bell (BD and alternative (ALT water facility and stocking densities (SD of 10 and 14 broilers m-2 (SD10 and SD14, on performance of 240 broiler chickens of 12 to 18, 19 to 38 and 39 to 46 days of age, allotted in boxes in a completely randomized design in 2 x 2 factorial arrangement (two types of drinking facility and two stocking densities, resulting in four treatments, each one with five replications of ten birds. The ALT was developed based on

In vitro cytotoxicity and in vivo osseointergration properties of compression-molded HDPE-HA-Al2O3 hybrid biocomposites.

Science.gov (United States)

Tripathi, Garima; Gough, Julie E; Dinda, Amit; Basu, Bikramjit

2013-06-01

The aim of this study was to investigate the in vivo biocompatibility in terms of healing of long segmental bone defect in rabbit model as well as in vitro cytotoxicity of eluates of compression-molded High density polyethylene (HDPE)-hydroxyapatite (HA)-aluminum oxide (Al2O3) composite-based implant material. Based on the physical property in terms of modulus and strength properties, as reported in our recent publication, HDPE-40 wt % HA and HDPE-20 wt % HA-20 wt % Al2O3 hybrid composites were used for biocompatibility assessment. Osteoblasts cells were cultured in conditioned media, which contains varying amount of composite eluate (0.01, 0.1, and 1.0 wt %). In vitro, the eluates did not exhibit any significant negative impact on proliferation, mineralization or on morphology of human osteoblast cells. In vivo, the histological assessment revealed neobone formation at the bone/implant interface, characterized by the presence of osteoid and osteoblasts. The observation of osteoclastic activity indicates the process of bone remodeling. No inflammation to any noticeable extent was observed at the implantation site. Overall, the combination of in vitro and in vivo results are suggestive of potential biomedical application of compression-molded HDPE- 20 wt % HA- 20 wt % Al2O3 composites to heal long segmental bone defects without causing any toxicity of bone cells. Copyright © 2012 Wiley Periodicals, Inc.

ALTA: A BRDF analysis library

OpenAIRE

Belcour , Laurent; Barla , Pascal; Pacanowski , Romain

2014-01-01

International audience; In this document, we introduce ALTA, a cross platform generic open-source library for Bidirectional Reflectance Distribution Function (BRDF) analysis. Among others, ALTA permits to estimate BRDF models parameters from measured data, to perform statistical analysis and also to export BRDF data models in a wide variety of formats.

Effect of γ-aminopropyltriethoxy silane (γ-APS) coupling agent on mechanical and morphological properties of high density polyethylene (HDPE)/acrylonitrile butadiene rubber (NBR)/palm pressed fibre (PPF) composites

Science.gov (United States)

Norizan, Nabila Najwa; Santiagoo, Ragunathan; Ismail, Hanafi

2017-07-01

The fabrication of High Density Polyethylene (HDPE)/ Acrylonitrile-butadiene rubber (NBR)/ Palm Pressed Fibre (PPF) composite were investigated. The effect of γ-Aminopropyltriethoxy Silane (APS) as coupling agent on the properties of HDPE/ NBR/ PPF composite were studied. The composites were melt mixed using heated two roll mill at 180°C and speed of 15rpm with six different loading (100/0/10, 80/20/10, 70/30/10, 60/40/10, 50/50/10, and 40/60/10). The effects of γ-APS silane on mechanical, and morphological properties were examined using universal tensile machine (UTM) and scanning electron microscopy (SEM), respectively. Tensile strength and Young's modulus of HDPE/ NBR/ PPF composites decrease with increasing of NBR loading, whilst increasing the elongation at break. However, treated composites have resulted 3% to 29%, and 9% to 19%, higher in tensile strength and young's modulus compared to untreated composites. This was due to the better adhesion between HDPE/ NBR matrices and PPF filler with the presence of silanol moieties. From the morphological study, the micrograph of treated composites has proved the well bonded and good attachment of PPF filler with HDPE/ NBR matrices which resulted to better tensile strength to the HDPE/ NBR/ PPF composites.

Dynamic mechanical analysis of multi-walled carbon nanotube/HDPE composites.

Science.gov (United States)

Kanagaraj, S; Guedes, R M; Oliveira, Mónica S A; Simões, José A O

2008-08-01

Since the discovery of carbon nanotubes (CNTs), their remarkable properties make them ideal candidates to reinforce in advanced composites. In this attempt, an enhancement of mechanical properties of high density polyethylene (HDPE) by adding 1 wt% of CNTs is studied using Dynamic mechanical and Thermal analyzer (DMTA). The chemically treated and functionalized CNTs were homogeneously dispersed with HDPE and the test samples were made using injection molding machine. Using DMTA, storage modulus (E'), loss modulus (E") and damping factor (tan delta) of the sample under oscillating load were studied as a function of frequency of oscillation and temperatures. The storage modulus decreases with an increase of temperature and increases by adding CNTs in the composites where the reinforcing effect of CNT is confirmed. It is concluded that the large scale polymer relaxations in the composites are effectively restrained by the presence of CNTs and thus the mechanical properties of nanocomposites increase. The transition frequency of loss modulus is observed at 1 Hz. The loss modulus decreases with an increase of temperature at below 1 Hz but opposite trend was observed at above 1 Hz. The shift factor could be predicted from Williams-Landel-Ferry (WLF) model which has good agreement with experimental results.

Persamaan Prediksi Umur Simpan Filet Ikan Nila (Oreochromis niloticus yang Dikemas Vakum dalam HDPE

Directory of Open Access Journals (Sweden)

Rudi Riyanto

2014-06-01

Full Text Available Penelitian ini dilakukan untuk mendapatkan data laju penurunan mutu filet ikan nila (Oreochromis niloticus yang dikemas vakum dengan HDPE. Hasil analisis digunakan untuk menentukan indikator yang paling tepat untuk persamaan prediksi umur simpan menggunakan persamaan regresi. Dalam percobaan yang dilakukan filet ikan nila yang dikemas vakum dengan HDPE disimpan pada suhu 0, 10, 20, dan 30 oC. Parameter yang dianalisis adalah TVB-N, pH, TBA, Organoleptik (hedonik, dan TPC (aerob dan anaerob. Data yang dihasilkan menunjukkan bahwa suhu dan lama penyimpanan berpengaruh nyata terhadap laju penurunan mutu filet ikan nila (P<0,05. Berdasarkan tingkat kecepatan parameter mutu untuk mencapai limit toleransi, nilai TVB-N merupakan parameter mutu yang paling tepat untuk dijadikan parameter penentu kinetika pembusukan filet ikan nila. Kandungan TVB filet ikan nila yang disimpan pada suhu 30, 20, 10, dan 0 °C telah melampaui batas mutu (30 mg-N/100 g secara berturut-turut pada penyimpanan 9, 24, 72, dan 168 jam. Berdasarkan hasil pengolahan data nilai TVB filet ikan nila pada beberapa suhu penyimpanan menggunakan persamaan Arrhenius, nilai Ea yang didapatkan sebesar 72,17 KJ/mol dengan menggunakan nilai TVB 30 mg-N/100 g sebagai nilai batas penolakan mutu filet ikan nila. Persamaan prediksi umur simpan (t=jam filet ikan nila dalam HDPE vakum yang didapatkan adalah ln A = ln A0 + (t.exp[26,44-8681(1/T] dengan tingkat akurasi nilai prediksi terhadap nilai mutu filet ikan nila percobaan adalah 73–78%.

Nucleation and growth of apatite on NaOH-treated PEEK, HDPE and UHMWPE for artificial cornea materials.

Science.gov (United States)

Pino, M; Stingelin, N; Tanner, K E

2008-11-01

The skirt of an artificial cornea must integrate the implant to the host sclera, a major failure of present devices. Thus, it is highly desirable to encourage the metabolic activity of the cornea by using more bioactive, flexible skirt materials. Here we describe attempts to increase the bioactivity of polyether ether ketone (PEEK), high-density polyethylene (HDPE) and ultra-high molecular weight polyethylene (UHMWPE) films. The effectiveness of different strength NaOH pre-treatments to initiate apatite deposition on PEEK, HDPE and UHMWPE is investigated. We find that exposure of PEEK, HDPE and UHMWPE films to NaOH solutions induces the formation of potential nuclei for apatite (calcium phosphate), from which the growth of an apatite coating is stimulated when subsequently immersing the polymer films in 1.5 strength Simulated Body Fluid (SBF). As immersion time in SBF increases, further nucleation and growth produces a thicker and more compact apatite coating that can be expected to be highly bioactive. Interestingly, the apatite growth is found to also be dependent on both the concentration of NaOH solution and the structure of the polymer surface.

Research on the suitability of organosolv semi-chemical triticale fibers as reinforcement for recycled HDPE composites

Directory of Open Access Journals (Sweden)

Nour-Eddine El Mansouri

2012-11-01

Full Text Available The main objective of this research was to study the feasibility of incorporating organosolv semi-chemical triticale fibers as the reinforcing element in recycled high density polyethylene (HDPE. In the first step, triticale fibers were characterized in terms of chemical composition and compared with other biomass species (wheat, rye, softwood, and hardwood. Then, organosolv semi-chemical triticale fibers were prepared by the ethanolamine process. These fibers were characterized in terms of its yield, kappa number, fiber length/diameter ratio, fines, and viscosity; the obtained results were compared with those of eucalypt kraft pulp. In the second step, the prepared fibers were examined as a reinforcing element for recycled HDPE composites. Coupled and non-coupled HDPE composites were prepared and tested for tensile properties. Results showed that with the addition of the coupling agent maleated polyethylene (MAPE, the tensile properties of composites were significantly improved, as compared to non-coupled samples and the plain matrix. Furthermore, the influence of MAPE on the interfacial shear strength (IFSS was studied. The contributions of both fibers and matrix to the composite strength were also studied. This was possible by the use of a numerical iterative method based on the Bowyer-Bader and Kelly-Tyson equations.

Mechanical properties of HDPE/UHMWPE blends: effect of filler loading and filler treatment.

Science.gov (United States)

Lai, K L K; Roziyanna, A; Ogunniyi, D S; Zainal, Arifin M I; Azlan, Ariffin A

2004-05-01

Various blend ratios of high-density polyethylene (HDPE) and ultra high molecular weight polyethylene (UHMWPE) were prepared with the objective of determining their suitability as biomaterials. In the unfilled state, a blend of 50/50 (HDPE/UHMWPE) ratio by weight was found to yield optimum properties in terms of processability and mechanical properties. Hydroxyapatite (HA) was compounded with the optimum blend ratio. The effects of HA loading, varied from 0 to 50wt% for both filled and unfilled blends were tested for mechanical properties. It was found that the inclusion of HA in the blend led to a remarkable improvement of mechanical properties compared to the unfilled blend. In order to improve the bonding between the polymer blend and the filler, the HA used was chemically treated with a coupling agent known as 3-(trimethoxysiyl) propyl methacrylate and the treated HA was mixed into the blend. The effect of mixing the blend with silane-treated HA also led to an overall improvement of mechanical properties.

Study of mechanical and morphological properties of bio-based polyethylene (HDPE) and sponge-gourds (Luffa-cylindrica) agroresidue composites

Science.gov (United States)

Escocio, Viviane A.; Visconte, Leila L. Y.; Cavalcante, Andre de P.; Furtado, Ana Maria S.; Pacheco, Elen B. A. V.

2015-05-01

Brazil has a remarkable position in the use of renewable energy. The potential of natural resources in Brazil has motivated the use of these renewable resources to make technologies more sustainable. From the large variety of commercially available High Density Polyethylene (HDPE) from different sources, two were chosen for investigation: one produced from sugarcane ethanol, and the other one, a conventional polyethylene, produced from fossil resources. In the preparation of the composites, sponge-gourds also called Luffa cylindrica were selectec. The main application of this product is as bath sponge, whose production generates scraps that are generally burnt. In this work, the composites were prepared by blending the sponge scrap at different proportions (10, 20, 30 and 40% wt/wt) with high density polyethylene (HDPE) from renewable source by extrusion. The melt flow index analysis of the composites was determined and specimens were obtained by injection molding for the assessment of mechanical properties such as tensile (elasticity modulus), flexural and Izod impact strengths. The microstructure of the impact fractured surface of the specimen also was determined. The results showed that the addition of sponge scrap affects positively all the properties studied as compared to HDPE. The results of tensile strength, elasticity modulus and flexural strength were similar to those observed in the literature for composites of HDPE from fossil source. The microstructure corroborates the results of mechanical properties. It was shown that the sponge scrap has potential to be applied as cellulosic filler for renewable polyethylene, providing a totally renewable material with good mechanical properties.

Metodologia para estudo do volume e densidade absoluta da placenta humana de termo

Directory of Open Access Journals (Sweden)

Del Nero Ulisses

2002-01-01

Full Text Available OBJETIVO: comparar duas metodologias para o cálculo do volume placentário em gestações normais de termo: a do princípio de Arquimedes e a do volume do cilindro, para estimar a densidade absoluta da placenta. Definir a metodologia mais adequada para o cálculo do volume e densidade placentários, que se relacione com o peso e classificação do recém-nascido. MÉTODOS: foram estudadas 50 placentas provenientes de gestações de termo sem complicações e calculados o volume e a densidade absoluta placentários: a pelo princípio de Arquimedes e b na suposição de que a placenta seria uma secção de cilindro com duas alturas diferentes do bolo placentário: com a altura média e com a altura da média aritmética do centro e extremidades. As densidades absolutas placentárias foram calculadas pelo quociente entre o peso ao ar da placenta e os diferentes volumes. RESULTADOS: a maioria das gestantes eram multíparas, idade média de 25,4 anos, volume placentário médio entre 547,8 e 610 cmsuperscript three e densidade média entre 0,94 e 1,14 g/cmsuperscript three, dependendo da metodologia empregada. CONCLUSÕES: a metodologia mais adequada para estimar o volume placentário no termo foi a do princípio de Arquimedes, pela melhor correlação com o peso dos recém-nascidos, o índice placentário e a classificação do peso dos recém-nascidos em relação à idade gestacional.

SURFACE MODIFICATION OF SUGARCANE BAGASSE CELLULOSE AND ITS EFFECT ON MECHANICAL AND WATER ABSORPTION PROPERTIES OF SUGARCANE BAGASSE CELLULOSE/ HDPE COMPOSITES

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Daniella Regina Mulinari

2010-05-01

Full Text Available Cellulose fibres from sugarcane bagasse were bleached and modified by zirconium oxychloride in order to improve the mechanical properties of composites with high density polyethylene (HDPE. The mechanical properties of the composites prepared from chemically modified cellulose fibres were found to increase compared to those of bleached fibres. Tensile strengths of the composites showed a decreasing trend with increasing filler content. However, the values for the chemically modified cellulose fibres/HDPE composites at all mixing ratios were found to be higher than that of neat HDPE. Results of water immersion tests showed that the water absorption affected the mechanical properties. The fracture surfaces of the composites were recorded using scanning electron microscopy (SEM. The SEM micrographs revealed that interfacial bonding between the modified filler and the matrix was significantly improved by the fibre modification.

Evaluación de los métodos directo, precipitado y Friedewald para la cuantificación de colesterol LDL y HDL en pollos de engorde

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José Henry Osorio

2012-12-01

Full Text Available El objetivo fue evaluar los métodos directo y precipitado para el colesterol de las lipoproteínas de alta densidad y los métodos directo, precipitado y Friedewald para el colesterol de las lipoproteínas de baja densidad en pollos de engorde. Se obtuvo suero de 30 pollos de engorde de 36 días de edad, en ayunas, de la línea Cobb 500, se determinaron los niveles de triglicéridos y colesterol total usando un kit enzimático-colorimétrico. El colesterol, tanto de las lipoproteínas de alta densidad como de las de baja densidad, se midió por el método de precipitación y el método directo, y la estimación del colesterol de la lipoproteína de baja densidad se determinó usando la fórmula de Friedewald. Las medias ± desviación estándar para los niveles de colesterol de las lipoproteínas de alta densidad, por los métodos directo y precipitado, en mg/dl, fueron de: 92,8 ± 16,7; 92,2 ± 16,3, respectivamente. El valor P del test F es mayor a 0,05, por lo cual no hay diferencia estadísticamente significativa, con un índice de confianza de 95 % entre métodos, y para los niveles de colesterol de la lipoproteínas de baja densidad por los métodos directo, precipitado y Friedewald, en mg/dl, fueron: 51,8 ± 9,4; 21,9 ± 12,6 y 26,1 ± 12,9, respectivamente. El valor P del test F es inferior a 0,05 evidenciando diferencia estadísticamente significativa, con un índice de confianza de 95 % entre métodos. Se concluye que en los pollos de engorde se puede cuantificar el colesterol de la lipoproteína de alta densidad con los dos métodos evaluados (directo y precipitado, sin embargo, para calcular el colesterol de la lipoproteína de baja densidad solo se recomienda utilizar el método directo ya que los métodos de precipitado y de Friedewald dieron resultados mucho menores en dicha especie.

Embalse de Puente Alta

OpenAIRE

Isabel Crespo, Josué

2014-01-01

El presente proyecto de construcción define todas las actuaciones necesarias para la realización de las obras del Embalse de Puente Alta, ubicado en el término municipal de Revenga, provincia de Segovia. El proyecto se plantea debido a las previsiones de fuerte crecimiento poblacional, con motivo de la llegada del Tren de Alta Velocidad, puesto que el mantenimiento de la situación actual podría causar en su momento un déficit estructural en esta zona.

Caracterización superficial, electroquímica y de composición de aleaciones zinc níquel electrodepositadas

OpenAIRE

PIRATOBA, ULISES; VERA, ENRIQUE; ORTIZ, CESAR

2008-01-01

La gran demanda de láminas de acero recubiertas con Zinc o con aleaciones de Zinc, es atendida conprocesos de electro deposición en continuo; estos requieren de altas densidades de corriente, obtenidas en electrolitos ácidos. En este trabajo se presenta la composición, morfología superficial y la caracterización electroquímica de aleaciones Zinc Níquel fase gamma sobre láminas de acero, depositadas con altas densidades de corriente. Estas fueron determinadas mediante Análisis de Energía Disp...

Addition of nitrogen had no effect on yield and quality of apples in an high density orchard carrying a dwarf rootstock A adição de nitrogênio não afetou o rendimento e a qualidade de maçãs em pomar com alta densidade e porta-enxerto anão

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Paulo Roberto Ernani

2008-12-01

alta densidade sobre porta-enxerto anão (M.9. O pomar com a cultivar Royal Gala foi plantado em 1995, na densidade de 2.857 plantas ha-1, em um Latossolo Bruno com 40 g kg-1 de matéria orgânica e pH 6,0. O experimento foi implantado em 1998 e foi encerrado em 2005. Os tratamentos consistiram da aplicação anual de 0; 50; 100 e 150 kg ha-1 de N de 1998 até 2001 e de, respectivamente, 0; 100; 200 e 300 kg ha-1 de N a partir da safra 2002-2003. Metade de cada dose foi aplicada no início da brotação, e o restante após a colheita, sempre na forma de sulfato de amônio. A aplicação de N ao solo não influenciou no rendimento de frutos em nenhuma das seis safras, independentemente da dose. Na média das doses e dos anos, o rendimento foi de 52,3 t ha-1. A adição de N também não afetou a concentração de N nas folhas (média de 24 g kg-1 e nos frutos (media de 346 mg kg-1, nem tampouco os atributos relacionados com a qualidade dos frutos (cor da epiderme, firmeza da polpa, acidez, sólidos solúveis, desordens fisiológicas. Alguns atributos relacionados com o vigor das plantas, entretanto, aumentaram com o aumento da dose de N. Portanto, em solos profundos do Sul do Brasil, com alto teor de matéria orgânica, não é necessário aplicar N para obter altas produtividades e frutos de boa qualidade em pomares de 'Royal Gala' contendo porta-enxerto anão (M.9 e alta densidade de plantas, provavelmente porque a necessidade das árvores é suprida pelo N oriundo da decomposição orgânica.

Preparation and properties of banana fiber-reinforced composites based on high density polyethylene (HDPE)/Nylon-6 blends.

Science.gov (United States)

Liu, H; Wu, Q; Zhang, Q

2009-12-01

Banana fiber (BaF)-filled composites based on high density polyethylene (HDPE)/Nylon-6 blends were prepared via a two-step extrusion method. Maleic anhydride grafted styrene/ethylene-butylene/styrene triblock polymer (SEBS-g-MA) and maleic anhydride grafted polyethylene (PE-g-MA) were used to enhance impact performance and interfacial bonding between BaF and the resins. Mechanical, crystallization/melting, thermal stability, water absorption, and morphological properties of the composites were investigated. In the presence of SEBS-g-MA, better strengths and moduli were found for HDPE/Nylon-6 based composites compared with corresponding HDPE based composites. At a fixed weight ratio of PE-g-MA to BaF, an increase of BaF loading up to 48.2 wt.% led to a continuous improvement in moduli and flexural strength of final composites, while impact toughness was lowered gradually. Predicted tensile modulus by the Hones-Paul model for three-dimensional random fiber orientation agreed well with experimental data at the BaF loading of 29.3 wt.%. However, the randomly-oriented fiber models underestimated experimental data at higher fiber levels. It was found that the presence of SEBS-g-MA had a positive influence on reinforcing effect of the Nylon-6 component in the composites. Thermal analysis results showed that fractionated crystallization of the Nylon-6 component in the composites was induced by the addition of both SEBS-g-MA and PE-g-MA. Thermal stability of both composite systems differed slightly, except an additional decomposition peak related to the minor Nylon-6 for the composites from the HDPE/Nylon-6 blends. In the presence of SEBS-g-MA, the addition of Nylon-6 and increased BaF loading level led to an increase in the water absorption value of the composites.

Durability and Reliability of Large Diameter HDPE Pipe for Water Main Applications (Web Report 4485)

Science.gov (United States)

Research validates HDPE as a suitable material for use in municipal piping systems, and more research may help users maximize their understanding of its durability and reliability. Overall, corrosion resistance, hydraulic efficiency, flexibility, abrasion resistance, toughness, f...

Influencia de la densidad y del confinamiento con geotextil en columnas de grava

OpenAIRE

Miranda Manzanares, Marina

2014-01-01

RESUMEN: El tratamiento con columnas de grava es uno de los métodos de mejora del terreno empleados habitualmente para la cimentación de terraplenes o estructuras sobre suelos blandos. El estudio realizado en esta Tesis Doctoral se centra en analizar: - La influencia de la densidad de la grava de la columna - El empleo de columnas ensacadas con geotextil. El análisis de la influencia de la densidad de la grava se ha realizado mediante ensayos realizados en laboratorio en modelo reducido con d...

Influencia de la densidad y del confinamiento con geotextil en columnas de grava

OpenAIRE

Miranda Manzanares, Marina

2014-01-01

El tratamiento con columnas de grava es uno de los métodos de mejora del terreno empleados habitualmente para la cimentación de terraplenes o estructuras sobre suelos blandos. El estudio realizado en esta Tesis Doctoral se centra en analizar: - La influencia de la densidad de la grava de la columna - El empleo de columnas ensacadas con geotextil. El análisis de la influencia de la densidad de la grava se ha realizado mediante ensayos realizados en laboratorio en modelo reducido con dos densid...

Dosimetric evaluation of multi-sided irradiation on HDPE pipes under 2 MeV electron beam

Energy Technology Data Exchange (ETDEWEB)

Benny, P.G., E-mail: bennypg@yahoo.com; Khader, S.A.; Sarma, K.S.S.

2014-03-01

The use of electron beam technology has enabled the production of heat resistant pipe for hot water circulation. One of the difficulties in the irradiation of pipe products is the uneven penetration of electrons. Quality of the radiation process depends on radiation dose and homogeneity of the dose distribution, which becomes a major concern when treatments of circular objects like pipes are performed. One method to achieve uniformity in the absorbed dose in the product is to use multi-sided irradiation. The paper discusses the importance of dosimetry mapping in industrial electron beam radiation processing and outlines the challenges in delivering a uniform dose to cylindrical objects. In this study, HDPE pipe of 5 mm thickness of homogeneous material (40 mm outer diameter and 30 mm inner diameter) has been chosen for multi-sided irradiation under 2 MeV scanned electron beam from the ILU-6 accelerator. - Highlights: • The paper outlines the challenges in delivering uniform dose to cylindrical objects at 2 MeV industrial electron beam facility. • HDPE pipe of 40 mm outer diameter and 30 mm inner diameter has been chosen for the study. • The circumferential dose distribution inside and outside of the pipes were evaluated by using calibrated CTA dosimeter strips. • Using stack of dosimeter strips, changes in circumferential dose distribution in the annular region of the pipe was evaluated. • Optimization of multi-sided irradiation on the HDPE pipes for better dose homogeneity is reported in the paper.

Effect of phenol formaldehyde resin as vulcanizing agent on flow behavior of HDPE/PB blend

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Moayad N. Khalaf

2014-07-01

Full Text Available Thermoplastic elastomer (TPE based on High density polyethylene (HDPE/polybutadiene (HDPE/PB = 70/30 parts blends containing 1, 3, 5, 7 and 10 wt.% of dimethylol phenolic resin as a vulcanizing agent in the presence of SnCl2 as catalyst was prepared. The dimethylol phenolic resin was prepared in our laboratory. The blends were compounded in mixer-60 attached to a Haake rheochord meter-90. The rheological properties were measured at temperatures 140, 160, 180 and 200 °C. The linearity of the flow curve appeared for 5% of the vulcanizing agent. The shear stress and shear viscosity have increased upon increasing the shear rate over a range of loading levels of vulcanizing agent of 1%, 3%, 5%, 7% and 10%. This may be attributed to the increased vulcanization between polyethylene and the rubber blend. The flow behavior index of the system shows a pseudo plastic nature behavior (since n < 1. The consistency index (K increased with the increase in the phenol formaldehyde resin content and the temperature. Hence, the increase in the value of the consistency index (K of the polymer melts refers to more viscous materials prepared. The activation energy for the TPE blends fluctuated indicating that there is phase separation; where each polymer behaved separately. This study showed that HDPE/PB blends are characterized with good rheological properties, which can be recommended to be processed with the injection molding technique.

Dosimetric evaluation of multi-sided irradiation on HDPE pipes under 2 MeV electron beam

International Nuclear Information System (INIS)

Benny, P.G.; Khader, S.A.; Sarma, K.S.S.

2014-01-01

The use of electron beam technology has enabled the production of heat resistant pipe for hot water circulation. One of the difficulties in the irradiation of pipe products is the uneven penetration of electrons. Quality of the radiation process depends on radiation dose and homogeneity of the dose distribution, which becomes a major concern when treatments of circular objects like pipes are performed. One method to achieve uniformity in the absorbed dose in the product is to use multi-sided irradiation. The paper discusses the importance of dosimetry mapping in industrial electron beam radiation processing and outlines the challenges in delivering a uniform dose to cylindrical objects. In this study, HDPE pipe of 5 mm thickness of homogeneous material (40 mm outer diameter and 30 mm inner diameter) has been chosen for multi-sided irradiation under 2 MeV scanned electron beam from the ILU-6 accelerator. - Highlights: • The paper outlines the challenges in delivering uniform dose to cylindrical objects at 2 MeV industrial electron beam facility. • HDPE pipe of 40 mm outer diameter and 30 mm inner diameter has been chosen for the study. • The circumferential dose distribution inside and outside of the pipes were evaluated by using calibrated CTA dosimeter strips. • Using stack of dosimeter strips, changes in circumferential dose distribution in the annular region of the pipe was evaluated. • Optimization of multi-sided irradiation on the HDPE pipes for better dose homogeneity is reported in the paper

Study of the Mechanical and Morphology Properties of Recycled HDPE Composite Using Rice Husk Filler

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Jia Ying Tong

2014-01-01

Full Text Available WPCs are being used in a large number of applications in the automotive, construction, electronic, and aerospace industries. There are an increasing number of research studies and developments in WPC technology involving rice husk as fillers. This study investigated the effects of different compositions of rice husk (RH filler on the mechanical and morphological properties of recycled HDPE (rHDPE composite. The composites were prepared with five different loading contents of RH fibers (0, 10, 20, 30, and 40 wt% using the twin screw extrusion method. Maleic acid polyethylene (MAPE was added as a coupling agent. Results showed that tensile and flexural properties improved with increasing RH loading. However, the impact strength of the composites decreased as the RH loading increased. SEM micrographs revealed good interfacial bonding between the fiber and polymer matrix.

Study of herbicide ametryne degradation in HDPE packaging using the advanced oxidation process by ionizing radiation

International Nuclear Information System (INIS)

Andrade, Debora Cristina de

2008-01-01

This study is part of the project with the objective to evaluate pesticides degradation for decontamination of commercial polymeric packaging of high density polyethylene, HDPE, used in agriculture. The herbicide used to this study was the herbicide ametryne (commercial name, Gesapax 500), due to its great use, mainly on field crops and on corn. Ametryne is commercialized since 1975, and, depending on the pesticide formulation and type of application, residues may be detectable in water, soil and on the surfaces for months or years. In order to evaluate the efficiency of radiation processing on removal the pesticides contamination, HDPE packaging were irradiated using Radiation Dynamics Electron Beam Accelerator with 1,5 MeV energy and 37 kW, in batch system. The samples were irradiated with water, in various absorbed doses. Ametryne was analyzed by gas chromatography (GC Shimadzu 17A), after extraction with hexane/dichloromethane (1:1 v/v) solution. The calibration curve was obtained with a regression coefficient of 0.986, and the relative standard deviation was lower than 10%. The radiation processing yield was evaluated by the rate of ametryne degradation and by the destruction G-value (Gd). The electron beam irradiation processing, showed high efficiency in destroying ametryne in the HDPE packaging when the samples were irradiated in presence of small quantities of water. (author)

THE ANALYSIS OF PARTIAL DISCHARGE (PD FROM ELECTRICAL TREEING IN LINEAR LOW DENSITY POLYETHYLENE (LLDPE AND HIGH DENSITY POLYETHYLENE (HDPE

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Hermawan Hermawan

2012-02-01

Full Text Available Recently, the transmission of electric energy has been developed by insulated cable. The suitable materialas an insulated cable is LLDPE and HDPE. In order to understand the quality of insulation system, themeasuring of PD has done. PD could begin completely insulation failure (breakdown. Therefore, it is veryimportant to understand the characteristic of PD and the enclose event on it, because PD is a main factorwhich caused insulation failure.This paper presents the result of PD measurement in the laboratory that used needle-plane electrode. Itwas supported by equipments such as osiloskop Digital GDS 2104 GW Instek, HPF, and RC detector.Polymer sample that used in this research is LLDPE (Linier Low Density Polyethylene and HDPE with 20x 4 x 25 mm3 dimension in each. Needle was made by steel (length 50 mm and diameter 1.15 mm, it wasstick to the polymer material. The distance between needle to the plane is 5 mm. The applied voltage foreach sample was 16 kVrms, 18 kVrms, 20 kVrms and 22 kVrms. The Taking of PD data was done in thefirst minute, 10th minute, 20th and so on until 180th minute.The measurement result shows that the characteristic of PD number and maximum charge as a function oftime and as a function of applied voltage inclined increasing both on LLDPE and HDPE. But, PD intensityin HDPE is higher than LLDPE.

Densidade de estocagem na engorda de camarão-branco cultivado em sistema de biofloco

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Charles Fróes

2013-08-01

Full Text Available O objetivo deste trabalho foi determinar a densidade de estocagem ideal para o cultivo de camarão-branco, em sistema de biofloco sem renovação de água. Foram realizados dois experimentos inteiramente casualizados, com três repetições para cada tratamento. No primeiro, juvenis de camarão-branco, com peso médio inicial de 1,23±0,09 g, foram cultivados a densidades de estocagem de 833, 1.250, 1.667, 2.083 e 2.500 camarões por m³. No segundo experimento, o peso médio inicial foi de 6,32±0,7 g, e as densidades foram de 566, 833, 1.111, 1.388 e 1.667 camarões por m³. Os melhores resultados de produtividade, com médias de 9,92 e 10,77 kg m-3, foram obtidos com 1.667 e 1.111 camarões por m³, respectivamente, no primeiro e segundo experimentos. O aumento da densidade de estocagem afeta o crescimento e a sobrevivência do camarão-branco em sistema de biofloco.

Caracterización de la composición y fluctuaciones en la densidad y diversidad de los ensambles planctónicos en cuatro humedales de Tarapacá

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Esteban Quinan

2016-12-01

Full Text Available La limnología de los humedales interiores en Tarapacá presenta ciclos productivos altamente dependientes de las lluvias estivales y las condiciones fisicoquímicas del medio. Entre 2013 y 2015 se estudiaron ensambles planctónicos de dos lagunas de evaporación y dos quebradas, durante dos temporadas productivas y dos vegetativas, junto con esto se observaron las condiciones fisicoquímicas asociadas. Los resultados mostraron que el fitoplancton en general estuvo dominado por diatomeas y solo en una quebrada por algas verdes, mientras que el zooplancton presentó composiciones muy distintas entre las lagunas y entre las quebradas, con importantes variaciones temporales. En lagunas las densidades altas de zooplancton asociaron positivamente con sólidos disueltos totales y su diversidad inversamente con la temperatura, por su parte la diversidad de fitoplancton mantuvo una relación inversa con la riqueza de zooplancton.

Migration of residual nonvolatile and inorganic compounds from recycled post-consumer PET and HDPE

Energy Technology Data Exchange (ETDEWEB)

Dutra, Camila; Reyes, Felix G.R., E-mail: reyesfgr@fea.unicamp.br [Universidade de Campinas (UNICAMP), SP (Brazil). Escola de Engenharia dos Alimentos. Dept. de Ciencias dos Alimentos; Freire, Maria Teresa de A. [Universidade de Sao Paulo (USP), Pirassununga, SP (Brazil). Fac. de Ciencia Animal e Engenharia dos Alimentos. Dept. de Engenharia dos Alimentos; Nerin, Cristina; Bentayeb, Karim; Rodriguez-Lafuente, Angel; Aznar, Margarita [Dept. of Analytical Chemistry, Arago Inst. of Engineering Research, University of Zaragoza (Spain)

2014-04-15

Migration of nonvolatile and inorganic residual compounds from post-consumer recycled polyethylene terephthalate (PET) submitted to cleaning processes for subsequent production of materials intended to food contact, as well as from multilayer packaging material containing post-consumer recycled high-density polyethylene (HDPE) was determined. Tests were carried out using food simulant. Nonvolatile organic contaminants from PET, determined by liquid chromatography-mass spectrometry (UPLC-QqQ/MS), showed significant migration reduction as consequence of the more complex cleaning technologies applied. However, contaminants not allowed by Brazilian and European Union regulations were identified even in deep cleaning samples. Results from multilayer HDPE showed a greater number of contaminants when compared to recycled pellets. Inorganic contaminants, determined by inductively coupled plasma mass spectrometry were below the acceptable levels. Additional studies for identification and quantitation of unknown molecules which were not possible to identify in this study by UPLC-QqQ/MS are required to ascertain the safety of using post-consumer recycled packaging material. (author)

Respuesta fisiológica del ñame espino (Dioscorea Rotundata Poir a las densidades de siembra

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Dairo J. Pérez

2015-12-01

Full Text Available Esta investigación tuvo como objetivo estudiar la respuesta fisiológica del ñame espino (Dioscorea rotundata cv. brasilero en función del incremento de las densidades de siembra, bajo la oferta ambiental del Sinú medio. El estudio se llevó a cabo en la Universidad de Córdoba (Montería, Colombia, donde se evaluaron las densidades de siembra de 45.455, 30.303, 22.727 y 10.101 plantas/ha; bajo un diseño de Bloques Completos al Azar con tres repeticiones. Las variables de respuestas consideradas fueron la fotosíntesis neta (Pn, medida en tres etapas fenológicas (vegetativa, inicio y final de tuberización; y los índices de crecimiento: tasa absoluta de crecimiento (TAC, tasa de asimilación neta (TAN, tasa relativa de crecimiento (TRC e índice de área foliar (IAF. La Pn no varió entre las densidades de siembra (p≤0,05, pero después de la etapa vegetativa, se redujo en promedio un 19,14% para el inicio y final de la tuberización. La TAC y la TRC tuvieron similar tendencia, se incrementaron desde la etapa vegetativa, pero esta última se redujo al final del cultivo. La TAN comenzó a decrecer desde la etapa vegetativa con un leve incremento al final del ciclo. El IAF se incrementó significativamente a partir de la tuberización, para las densidades de siembra superiores a 10.101 plantas/ha, alcanzando valores entre 3,08 y 4,03. Se concluye que los índices de crecimiento a excepción del IAF y la Pn, no variaron entre las densidades de siembra, probablemente por la capacidad de la especie de regular su actividad fisiológica en función de la densidad de siembra.

Characterization of laser beam transmission through a High Density Polyethylene (HDPE) plate

Science.gov (United States)

Genna, S.; Leone, C.; Tagliaferri, V.

2017-02-01

Infrared (IR) light propagation in semicrystalline polymers involves mechanisms such as reflection, transmission, absorption and internal scattering. These different rates determine either the interaction mechanism, either the temperatures reached in the IR heating processes. Consequently, the knowledge of these rates is fundamental in the development of IR heating processes in order to avoid the polymer's damage and to increase the process energy efficiency. Aim of this work is to assess a simple procedure to determine the rates of absorbed, reflected, transmitted and scattered energy in the case of an unfilled High Density Polyethylene (HDPE) plate. Experimental tests were performed by exposing a HDPE plate, 3 mm in thickness, to a diode laser source, working at the fundamental wavelength of 975 nm. The transmitted power was measured by power meter, the reflected one by applying the Beer-Lambert law to sample of different thickness. IR thermal images were adopted to measure the absorbed ratio. The scattered ratio was measured by energetic balance, as difference between the incoming power and the other ratios. Finally, IR thermal images were adopted to measure the scattered ratio and to validate the procedure.

Parâmetros sangüíneos de pacu Piaractus mesopotamicus (Holmberg, 1887 alimentados com dietas suplementadas com cromo trivalente em duas densidades de estocagem - DOI: 10.4025/actascianimsci.v29i4.1019 Hematological parameters of pacu Piaractus mesopotamicus (Holmberg, 1887 fed diets supplemented with trivalent chromium in two stocking densities - DOI: 10.4025/actascianimsci.v29i4.1019

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Flávio Ruas de Moraes

2008-03-01

Full Text Available O objetivo deste trabalho foi avaliar os efeitos da suplementação com cromo trivalente (0, 6, 12 e 18 mg kg-1 de ração sobre as variáveis hematológicas de Piaractus mesopotamicus, mantidos em duas densidades de estocagem (4 e 20 kg m-3. Os mantidos na maior densidade e alimentados com dietas suplementadas com 0 e 6 mg de cromo kg-1 apresentaram redução do número de linfócitos circulantes, sugerindo má adaptação a essa condição de alta densidade. Nas dietas suplementadas com 12 e 18 mg kg-1, tal efeito não foi observado, porém verificou-se aumento do número de trombócitos no tratamento com 12 mg de cromo kg-1. A inexistência de diferença significativa entre os tratamentos, aos 30 dias, sugere a adaptação dos peixes ao tipo de alimento e à situação de alta densidade. Portanto, nas condições deste ensaio, a suplementação com 12 e 18 mg de cromo kg-1 é interessante como estratégia alimentar durante 15 dias.This work evaluated the effects of chromium supplementation on the hematological parameters of Piaractus mesopotamicus Holmberg, 1887 maintained in two stocking densities. Fish were fed diets supplemented with 0, 6, 12 and 18 mg trivalent chromium kg-1 dry ration and maintained at 4 and 20 kg m-3. The fish under high stocking density and fed diets supplemented with 0 and 6 mg kg-1 showed reduction in the number lymphocytes, which suggests non-adaptation to this condition of high density. This was not observed in fish fed diets supplemented with 12 and 18 mg chromium kg-1, but an increase in the number of thrombocytes was evident. The lack of difference between treatments after 30 days may suggest a possible adaptation of fish to the situation. It can be added that supplementation with 12 and 18 mg chromium kg-1 is an interesting feeding strategy for a period of 15 days.

Avaliação da macroporosidade e da densidade de partículas do solo através da microtomografia de raios-x

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A. Macedo

1999-12-01

Full Text Available A Ciência do Solo procura compreender e modelar os fenômenos ocorridos no solo, principalmente na zona não saturada. Como o entendimento de muitos desses fenômenos exige determinações em escalas que permitam incorporar aos modelos a variabilidade de poros e agregados, desenvolveu-se, na Embrapa Instrumentação Agropecuária, um tomógrafo de raios-X, de resolução micrométrica, com o objetivo de se obterem imagens, de forma não-destrutiva, de amostras de solo, com resolução espacial igual ou inferior a 100 μm. Foi possível projetar e construir um equipamento, de alta resolução, com baixo custo, comparativamente aos equipamentos comerciais disponíveis, cujos preços são proibitivos para aplicações em solo. Obtiveram-se imagens de amostras de solos com estrutura deformada, compostos por agregados de 212 a 250 μm, nos quais foram identificados poros medindo 100 μm ou menos. Poros dessas dimensões foram visualizados, também, em tomografias de amostras compostas de grãos de areia de 1 mm e capilares de vidro com diâmetros internos de 100, 200 e 300 μm. Tomografias de amostras não deformadas de solos evidenciaram, além de poros de 200 a 800 μm, partículas de alta densidade não-detectáveis com a tomografia de resolução milimétrica.

Densidades divergentes y segregación socio-espacial en la Bogotá de hoy: un análisis a partir de un índice de calidad de la densidad

OpenAIRE

Alfonso R, Óscar A

2016-01-01

La densidad poblacional de Bogotá es bastante diversa al decir de la amplitud de su rango, siendo el mínimo una persona por hectárea y el máximo de 622/ha. Las densidades más elevadas serían la opción más eficiente y socialmente deseable ante la disyuntiva de la densificación o la expansión metropolitana. El problema radica en si tal opción está dotada de la mejor calidad. El objetivo es demostrar que esto no ocurre pues al vincular tres factores que determinan la calidad de la oc...

Segregation effect of radiation induced crosslinking of HDPE: morphology change

International Nuclear Information System (INIS)

Deng Pengyang; Zhong Xiaoguang

2000-01-01

Scanning Electronic Microscopy has been used to study morphology of pure gel; sol-gel blend and sol-gel segregation samples of radiation induced crosslinking of HDPE. The results show that the morphology of segregation sample is the same as that of pure gel and different from that of sol-gel blend. This kind of morphology change proves that the sol-gel blend have occurred a liquid---solid phase segregation in the melting state. The liquid phase (sol) will naturally immersed in the network of the gel. (author)

Reconfiguración del territorio y política territorial: Dispersión y baja densidad en las áreas de crecimiento reciente de la ciudad de Tandil, provincia de Buenos Aires

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Licia Ríos

2014-06-01

Full Text Available En el marco del fenómeno de urbanización creciente, se verifican cambios en la configuración territorial que dan cuenta de la emergencia de procesos de expansión urbana dispersos en coexistencia con las tradicionales formas de gradiente por periferización del modelo de ciudad compacta. Tanto en la reestructuración territorial de las áreas metropolitanas como de las ciudades de menor rango, se manifiestan cambios específicos caracterizados por dinámicas demográficas y económicas intensas, en correspondencia con significativas transformaciones de los entornos periurbanos y rurales. El estudio del crecimiento urbano en la ciudad de Tandil busca explicar las relaciones entre las reconfiguraciones ocurridas en las áreas de crecimiento urbano reciente, y la planificación y gestión territorial. La tesis que subyace es que la política territorial favoreció las tendencias de expansión urbana dispersas y de baja densidad, en articulación con las dinámicas del mercado de suelos rururbanos y nuevas demandas socioculturales. La política territorial ha tenido una alta capacidad de incidencia en la configuración del territorio a partir del reconocimiento de nuevas tendencias, fundamentalmente las asociadas al crecimiento extensivo, disperso y de baja densidad, porque sus acciones y decisiones validan los nuevos modelos.

Examining Mechanical Strength Characteristics of Selective Inhibition Sintered HDPE Specimens Using RSM and Desirability Approach

Science.gov (United States)

Rajamani, D.; Esakki, Balasubramanian

2017-09-01

Selective inhibition sintering (SIS) is a powder based additive manufacturing (AM) technique to produce functional parts with an inexpensive system compared with other AM processes. Mechanical properties of SIS fabricated parts are of high dependence on various process parameters importantly layer thickness, heat energy, heater feedrate, and printer feedrate. In this paper, examining the influence of these process parameters on evaluating mechanical properties such as tensile and flexural strength using Response Surface Methodology (RSM) is carried out. The test specimens are fabricated using high density polyethylene (HDPE) and mathematical models are developed to correlate the control factors to the respective experimental design response. Further, optimal SIS process parameters are determined using desirability approach to enhance the mechanical properties of HDPE specimens. Optimization studies reveal that, combination of high heat energy, low layer thickness, medium heater feedrate and printer feedrate yielded superior mechanical strength characteristics.

Three Point Bending of Top-Hat Stiffened Chopped Short Fibre Ramie/HDPE Thermoplastic Composite Beam

Science.gov (United States)

Hadi, Bambang K.; Nuril, Yogie S.

2018-04-01

The use of natural fibre and thermoplastic matrices in composite materials increased significantly during the last decade especially in the automotive industries. Ramie is one of these potential natural fibres. In this paper, a three point bending of top-hat beam made of ramie/HDPE (High-Density-Polyethylene) composites was performed. Top-hat stiffened structures were common structures found in the aerospace industries. Nevertheless, these structures are beginning to be applied in automotive structures in the forms of chassis and bumpers. The ramie/HDPE composite was manufactured using hot-press technique. The temperature was set to be 135°C and the pressure was 6 bars. Chopped short ramie fibre was used, due to good drape ability characteristics. The experiments showed that the beams produced a large non-linearity. Linear Finite Element Analysis was carried out to be compared with the experimental data. The differences are reasonable.

Sistema Computacional para Ajuste de Funções Densidade de Probabilidade

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Daniel Henrique Breda Binoti

Full Text Available RESUMO Este trabalho teve por objetivo iniciar, implementar e validar um projeto de construção de um sistema computadorizado para ajuste de funções densidade de probabilidade. O FitFD foi desenvolvido utilizando-se a linguagem de programação Java. Como ambiente de desenvolvimento foram utilizadas a IDE (Integrated Development Environment Netbeans 7.1 e a JDK 7.3 (Java Development Kit. Os testes do sistema foram realizados em ambiente Windows. Foram implementadas no sistema as seguintes funções densidade de probabilidade: Weibull (2P, 3P, 2P com dap mínimo como locação, 3P truncada, hiperbólica (2P, 3P, 2P com dap mínimo como locação, 3P truncada, log-logística (2P, 3P, 2P com dap mínimo como locação, logística generalizada, Fatigue life (2P e 3P e Frechet (2P e 3P. O sistema desenvolvido auxilia os usuários na definição e escolha da fdp que melhor atenda suas necessidades, contudo melhorias são necessárias. O projeto iniciado mostrou-se eficiente para ajustes de funções de densidade probabilidade.

Pesque-solte: pesca repetitiva, variáveis hematológicas e parasitismo no peixe híbrido tambacu

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Daniela Nomura Varandas

2013-08-01

Full Text Available O objetivo deste trabalho foi avaliar a resposta hematológica e parasitológica de tambacus (Colossoma macropomum x Piaractus mesopotamicus submetidos ao estresse de captura e a diferentes densidades de estocagem, em sistema de pesque-solte. Foram utilizados 210 peixes com peso médio inicial de 785,33±152,02 g e comprimento total médio de 34,43±2,21 cm, mantidos em viveiros escavados e divididos em três grupos: sem pesca e baixa densidade (G1, com pesca e baixa densidade (G2, e com pesca e alta densidade (G3. Não houve diferença significativa entre os valores médios da concentração de hemoglobina, do número de eritrócitos, da contagem diferencial de leucócitos e da glicose. Os peixes do grupo G3 apresentaram número maior de parasitos e trombócitos, e menor ganho de peso e hematócrito. A atividade de pesque-solte, aliada à alta densidade de estocagem, pode prejudicar o equilíbrio orgânico e o desempenho zootécnico, o que favorece a parasitose.

In vitro biological evaluation of beta-TCP/HDPE--A novel orthopedic composite: a survey using human osteoblast and fibroblast bone cells.

Science.gov (United States)

Homaeigohar, S Sh; Shokrgozar, M A; Khavandi, A; Sadi, A Yari

2008-02-01

Beta-tricalcium phosphate reinforced high density polyethylene (beta-TCP/HDPE) was prepared to simulate bone composition and to study its capacity to act as bone tissue. This material was produced by replacing the mineral component and collagen soft tissue of the bone with beta-TCP and HDPE, respectively. The biocompatibility of the composite samples with different volume fractions of TCP (20, 30 and 40 vol %) was examined in vitro using two osteoblast cell lines G-292 and Saos-2, and also a type of fibroblast cell isolated from bone tissue, namely human bone fibroblast (HBF) by proliferation, and cell adhesion assays. Cell-material interaction with the surface of the composite samples was examined by scanning electron microscopy (SEM). The effect of beta-TCP/HDPE on the behavior of osteoblast and fibroblast cells was compared with those of composite and negative control samples; polyethylene (PE) and tissue culture polystyrene (TPS), respectively. In general, the results showed that the composite samples containing beta-TCP as reinforcement supported a higher rate of proliferation by various bone cells after 3, 7, and 14 days of incubation compared to the composite control sample. Furthermore, more osteoblast cells were attached to the surface of the composite samples when compared to the composite control samples after the above incubation periods (p HDPE composites are biocompatible, nontoxic, and act to stimulate proliferation and adhesion of the cells, whether osteoblast or fibroblast. (c) 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008.

Preparation and characterizations of HDPE-EVA alloy/OMT nanocomposites/paraffin compounds as a shape stabilized phase change thermal energy storage material

International Nuclear Information System (INIS)

Cai Yibing; Hu Yuan; Song Lei; Lu Hongdian; Chen Zuyao; Fan Weicheng

2006-01-01

A kind of shape stabilized phase change nanocomposites materials (PCNM) based on high density polyethylene (HDPE)/ethylene-vinyl acetate (EVA) alloy, organophilic montmorillonite (OMT), paraffin and intumescent flame retardant (IFR) are prepared using twin-screw extruder technique. The structures of the HDPE-EVA alloy/OMT nanocomposites are evidenced by the X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that an ordered intercalated nanomorphology of the HDPE-EVA alloy/OMT nanocomposites is formed. Then the structures of the shape stabilized PCNM are characterized by scanning electron microscopy (SEM). The HDPE-EVA alloy/OMT nanocomposites act as the supporting material and form the three-dimensional network structure. The paraffin acts as a phase change material and disperses in the three-dimensional network structure. Its latent heat is given by differential scanning calorimeter (DSC) method. The SEM and DSC results show that the additives of IFR have little effect on the network structure and the latent heat of shape stabilized PCNM, respectively. The thermal stability properties are characterized by thermogravimetric analysis (TGA). The TGA analysis results indicate that the flame retardant shape stabilized PCNM produce a larger amount of char residue at 800 deg. C than that of shape stabilized PCNM, although the onset of weight loss of the flame retardant shape stabilized PCNM occur at a lower temperature. The formed multicellular char residue contributes to the improvement of thermal stability performance. The probable combustion mechanisms are also discussed in this paper

RESISTENCIA MECÁNICA EVALUADA EN EL ENSAYO MARSHALL DE MEZCLAS DENSAS EN CALIENTE ELABORADAS CON ASFALTOS MODIFICADOS CON DESECHOS DE POLICLORURO DE VINILO (PVC, POLIETILENO DE ALTA DENSIDAD (PEAD Y POLIESTIRENO (PS MECHANICAL RESISTANCE OF HOT THICK MIXTURES MADE WITH ASPHALT MODIFIED WITH POLYVINYL CHLORIDE, POLYCLORURE (PVC WASTES, HIGH DENSITY POLYETHYLENE (PEAD, AND POLYSTYRENE (PS EVALUATED IN MARSHALL ASSAY

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Hugo Alexánder Rondón Quintana

2007-07-01

Full Text Available El presente trabajo buscó evaluar en laboratorio el cambio en la resistencia mecánica que experimentan mezclas asfálticas densas en caliente cuando se adicionan, por vía húmeda, al cemento asfáltico aditivos poliméricos producto de desechos industriales del tipo plastómero (policloruro de vinilo, polietileno de alta densidad y poliestireno. Para tal fin se empleó el ensayo Marshall. De los resultados obtenidos se concluye que la resistencia mecánica de mezclas asfálticas modificadas con desechos del tipo plastómero es mayor en comparación con las convencionales (mezclas que emplean asfaltos sin ningún aditivo.The main objective of this research Project was to evaluate in a laboratory the change in mechanical strength that dense hot asphalt mixtures go through when waste polymeric additives of plastomeric type (polyvinyl chloride, high density polyethylene and polystyrene are added to asphalt cement, by 'wet way'. This change was evaluated using Marshall Test. The general conclusion of the experimental results was that modified hot asphalt mixtures present better mechanical behavior than conventional mixtures (mixtures which use asphalt without additives.

Rendimiento de plantas de tomate injertadas y efecto de la densidad de tallos en el sistema hidropónico Yield of tomato crop as a result of grafting and shoot density in hydroponic system

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Roberta M.N. Peil

2004-06-01

Full Text Available El cultivo de tomate en primavera con baja densidad inicial de plantas y luego aumentar-se la densidad efectiva mediante el desarrollo de tallos laterales, cuando las integrales diarias de radiación son altas, parece ser una manera prometedora de incrementar el número de frutos m-2 y uniformizar el tamaño del fruto; y presenta la ventaja adicional de requerir-se un menor número de plantas para la superficie de cultivo. Por lo tanto, se ha llevado a cabo un ensayo cuyo objetivo ha sido evaluar los efectos de la densidad de tallos sobre el rendimiento y la uniformidad de los frutos de un cultivo de tomate injertado y no injertado. El cultivo se realizó de marzo a julio de 1998, en las condiciones de invernadero en Almería (sudeste español. La densidad inicial de plantación fue de 2,4 y 3,0 plantas m-2, en el caso de las plantas no injertadas, que presentaban un único tallo en el transplante; y 1,2 plantas m-2 en las plantas injertadas, que tenían dos tallos (2,4 tallos m-2. A partir del mes de abril, mediante el desarrollo de tallos laterales (cuando el tratamiento así lo exigía se pasó a tener las siguientes densidades: 2,4; 3,0 y 3,5 tallos m-2 (plantas injertadas y no injertadas; y 3,0 plantas no injertadas m-2 a un tallo durante todo el ciclo. Los resultados muestran que plantas de tomate injertadas y transplantadas a dos tallos tuvieron igual producción total, pero frutos de tamaño más uniforme, que plantas no injertadas transplantadas a un tallo y con doble densidad de plantas. Dentro del rango de 2,4 a 3,5 tallos m-2, una mayor densidad de tallos aumentó la producción precoz y dio un tamaño más uniforme de frutos, no afectando su peso promedio y la producción total. La adición de tallos laterales (3,0 tallos m-2 supuso una reducción de un 20% en el rendimiento total, pero vino acompañada por un ahorro de un 21% y de un 39% en el número de plantas no injertadas e injertadas, respectivamente, necesarias para la misma

Changes in wood flour/HDPE composites after accelerated weathering with and without water spray

Science.gov (United States)

Nicole M. Stark

2005-01-01

Wood-plastic lumber is promoted as a low-maintenance high-durability product. After weathering, however, wood-plasticcomposites (WPCs) often fide and lose mechanical properties. In the first part ofthis study, 50%wood-flour-filled high-density polyethylene (HDPE) composite samples were injection molded or extruded. Composites were exposed to two accelerated weathering...

Mechanical properties of concrete reinforced with recycled HDPE plastic fibres\\ud

OpenAIRE

Pešić, Ninoslav; Živanović, Stana; Garcia, Reyes; Papastergiou, Panos

2016-01-01

This work investigates potential engineering benefits of the pioneering application of simply extruded recycled high-density polyethylene (HDPE) plastic fibres in structural concrete. Mechanical and serviceability properties of concrete are studied through the testing of seven series of specimens: one made of the plain concrete and, for each of the two fibre diameters View the MathML source and View the MathML source, three series with 0.40%, 0.75% and 1.25% volume fraction of fibres. While t...

Altas capacidades en el aula /

OpenAIRE

Conesa Muñoz., María Gregoria

2014-01-01

Las altas capacidades necesitan un tratamiento específico, del mismo modo que lo necesitan otros alumnos con dificultades para el aprendizaje, el hecho de que les sea más fácil aprender no significa que no se deban potenciar sus capacidades. Se analiza el tratamiento que han tenido las altas capacidades intelectuales a lo largo de los diferentes sistemas educativos, se ven las características más importantes que pueden tener estos niños y las diferentes vías de identificación y diagnóstico. ...

Influência da densidade do solo no desenvolvimento inicial do pinhão-manso cultivado em Latossolo Vermelho eutroférrico

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Tatiane Ohland

2014-10-01

Full Text Available Este trabalho teve por objetivo avaliar a influência da densidade do solo no desenvolvimento inicial da cultura do pinhão-manso. O experimento foi realizado em vasos de 10,6 dm³, em casa de vegetação. O solo utilizado foi o Latossolo Vermelho eutroférrico de textura argilosa, coletado em Marechal Cândido Rondon - PR. O delineamento experimental utilizado foi o de blocos casualizados, composto por cinco níveis de densidade do solo (1,08; 1,22; 1,36; 1,50 e 1,64 kg dm-3, com quatro repetições. Após 120 dias da emergência das plantas, foram efetuadas as avaliações biométricas e as relativas ao do tecido vegetal. Houve redução de 25% da altura das plantas, na densidade de 1,64 kg dm-3, quando,comparada com a da densidade de 1,08 kg dm-3. Para o comprimento radicular, a redução foi de aproximadamente 24 , 35 , 54 e 66 % para as densidades de 1,22; 1,36; 1,50 e 1,64 kg dm-3 respectivamente, quando comparadas com o da densidade de 1,08 kg dm-3. A limitação do desenvolvimento da parte aérea ocorreu a partir da densidade estimada de 1,26 kg dm-3, com redução do número de folhas, da área foliar e da produção de matéria seca da parte aérea. O desenvolvimento do sistema radicular e o conteúdo de P e K nas plantas de pinhão-manso reduziram-se linearmente com o aumento da densidade do solo.

PROPIEDADES TECNOLÓGICAS DE LA MADERA DE ALGARROBO (Hymenaea oblongifolia Huber., DE BAGADÓ-CHOCÓ, COLOMBIA

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Yessica B. Serna Mosquera

2011-01-01

Full Text Available Este trabajo tuvo como objetivo determinar las propiedades tecnológicas de la madera de Hymenaea oblongifolia Huber algarrobo, proveniente del municipio de Bagadó-Chocó, Colombia. Las muestras tomadas de los árboles (cilindros de la madera fueron estudiadas para determinar las características microscópicas, la densidad básica y la densidad normal; además, se estimaron las propiedades mecánicas utilizando los valores de densidad básica. Los resultados indicaron que la madera presenta vasos escasos -de medianos a grandes-, las fibras son medianas y los radios son finos a moderadamente largos con células cristalíferas, presenta mala calidad para producción de pulpa para papel, la densidad básica de la madera se clasificó como semipesada, y presenta una resistencia mecánica que varía de alta a muy alta. Puede utilizarse en la elaboración de pisos, muebles y mangos decorativos, entre otros usos.

Alta peab tasuma Kalevile mais / Kersti Saar

Index Scriptorium Estoniae

Saar, Kersti

2008-01-01

Indrek Rahumaa juhitav Alta Capital peab tasuma Oliver Kruudale Kalevi tütarfirmade eest 660 miljonit krooni hiljemalt 30. maiks. Vt. samas: Investorid teavad tehingu hinda ja lõplikku tähtaega. Diagramm: Kalevi turuväärtus jääb Alta müügihinnale alla

El niño, oscilación del sur (ENOS, con relación a la transmisión de malaria, densidad y paridad de An. albimanus y An. darlingi (diptera: culicidae en dos regiones de Colombia

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Ricardo Mantilla

2000-02-01

Full Text Available

Una fuerte asociación ha sido registrada entre los incrementos en la transmisiónas forzadas por el fenómeno El Niño. Entre las posibles explicaciones para esta asociación está el efecto del clima sobre la dinámica de población de vectores, por ejemplo, generando cambios en la densidad y en las tasas de sobrevivencia de la población, y en la cantidad y calidad de sitios de reproducción, como también a través de cambios en el período de incubación extrínseco del parásito dentro del vector. Con el propósito de evaluar la influencia de ENOS sobre la densidad y paridad de Anopheles albimanus y An. darlingi, y su relación con la transmisión de malaria, se realizó un estudio longitudinal en Chocó y Casanare. En cada área se seleccionaron dos localidades y se realizaron muestreos entomológicos durante una semana cada mes, desde finales de 1997 hasta 1999. Este período cubrió los eventos El Niño 1997 -1998 y La Niña 1998 - 2000. En las localidades de Chocó se observó un importante incremento en el número de casos de malaria durante el evento ENOS, asociado con la temperatura. No se observó una asociación estadísticamente significativa entre los casos de malaria y la precipitación o la humedad relativa. La relación entre el incremento de malaria durante El Niño y las variables entomológicas no fue evidente. La densidad y paridad de ambas especies de vectores fluctuaron durante el período de estudio y no se encontró una asociación significativa entre estas variables y los factores climáticos como la temperatura. La precipitación y la humedad relativa. La densidad de larvas de An. albimanus fluctuó durante el estudio, y mostró altas densidades alrededor de julio - agosto. No se observó asociación entre la densidad de larvas con la densidad de adultos o las variables climáticas. El efecto del evento ENOS sobre las poblaciones de vectores

Development of Composite Made of HDPE and Fiber Reinforced Polymer Dust

International Nuclear Information System (INIS)

Muhamad Noor Izwan Ishak; Ismail Mustapha; Mohd Reusmazran Yusof; Yusof Abdullah; Nor Pai'za Mohamad Hasan; Mohamad Ridzuan Ahamad; Md Fakarudin Ab Rahman; Hafizal Yazid; Ainul Mardhiah Terry; Airwan Affandi Mahmood; Nurliyana Abdullah

2016-01-01

Full text: Composite of High Density Polyethylene and Fiber Reinforced Polymer Dust (HDPE/ FRPD) were prepared by melt mixing technique. The blend was mixed and compression molded by hydraulic press at 150 degree Celsius. Effect of blend ratio on mechanical properties of the developed composite was determined. Tensile properties of the blends found to show decreasing trend with addition of FRPD. While impact strength and hardness properties showed promising result. Reuse of ' Fiber Reinforced Polymer ' dust can be improved by the present invention. (author)

IDENTIFICACIÓN DE MICROALGAS OLEAGINOSAS EN EL ÁREA DE CONCESIÓN PARA CONSERVACIÓN, CUENCA ALTA DEL RÍO ITAYA. LORETO-PERÚ

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Marianela Cobos Ruiz

2012-12-01

Full Text Available Las microalgas oleaginosas constituyen una nueva alternativa para la producción de biodiesel, por su alta eficiencia fotobiosintética de triglicéridos y presentan productividades mayores de 10 a 100 veces que los cultivos convencionales. Además que actúan como sumideros de CO2 y pueden usar aguas servidas para producir biodiesel. Sin embargo, los estudios sobre identificación de este tipo de microalgas en la amazonía son escasos. El objetivo del presente trabajo de investigación fue identificar especies de microalgas oleaginosas con potencial aplicación para la producción de biodiesel que se encuentran en ambientes acuáticos del Área de Concesión para Conservación de la Universidad Científica del Perú (UCP. La colecta de las muestras se realizó del 27/06/12 al 03/07/12 entre las 12 y 15 h utilizando red planctónica tipo cono y como preservante formol al 3%. La identificación microscópica se realizó en el Laboratorio de Ciencias Básicas de la UCP. La densidad de las microalgas fue realizada en base a su conteo en cámaras de Neubauer  y Sedgwick-Rafter. Los resultados muestran la presencia de 20 especies de microalgas, de las cuales cinco son microalgas oleaginosas. Correspondiente a las del género Chlorella quienes presentaron la mayor densidad promedio (6x104 células/ml en las tres cochas evaluadas.

Tensile behaviour and properties of a bone analogue composite (HA, HDPE) crosslinked by gamma radiation

International Nuclear Information System (INIS)

Romero, G.; Smolko, Eduardo E.

2005-01-01

A natural composite material, hydroxyapatite (HA) and high density polyethylene (HDPE) crosslinked by ionizing radiations is been developed as a bioactive analogue material for bone replacement. Mechanical properties of the composites irradiated up to 300 kGy under tensile tests was studied. Gel content and micrographs of different composite fractures are shown. (author)

γ-Radiation (0-150 kGy) Effects on HDPE/LDPE Blends

International Nuclear Information System (INIS)

Albano, C.

2006-01-01

In the present work, irradiation with 60 C o source was employed to study the effect of γ-rays on some physical properties of HDPE/LDPE blends (0/100, 10/90, 25/75, 50/50, 75/25, 100/0), using various doses: 0, 50, 150 kGy. The blends were prepared by extrusion and plates were compression molded employing fast and slow cooling methods from the melt. Density, degree of crystallinity and mechanical properties were dependant on the cooling rate used and blend composition. Better properties were found for HDPE-rich blends. Mechanical properties showed no significant variations in tensile modulus and yield stress. Instead, a decrease in elongation at break, due to molecular crosslinking or branching reaction effects, with the raise of radiation dose was obtained. Density measurements and differential scanning calorimetry results failed to exhibit significant changes with radiation dose. Some qualitative aspects included changes in endotherms shape. These were attributed to the variation of in crystallite sizes, probably due to structural changes originated by crosslinking and chain scission reactions occurring as a result of γ-rays exposure. On the other hand, there was an abrupt reduction of the melt flow index (MFI) from the range of 16-9 dg/min for 0 kGy to non-fluidity for an exposure of 150 kGy; this behavior is another sign of high crosslinking, impairing the viscous fluidity of the blends

Densidade de plantio, crescimento, produtividade e qualidade das frutas de morangueiro "Camino Real" em hidroponia

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Isabelita Pereira Portela

2012-09-01

Full Text Available Com o objetivo de determinar o efeito da densidade de plantio sobre o crescimento da planta, a produtividade e características químicas relacionadas à qualidade organoléptica das frutas da cultivar de morangueiro Camino Real em sistema hidropônico do tipo NFT, diferentes densidades de plantio foram avaliadas: 15,0; 12,5; 10,7 e 9,3 plantas m-2, correspondentes ao espaçamento entre plantas de 0,25; 0,30; 0,35 e 0,40 m, sendo fixado o espaçamento entre linhas de 0,18 m. O sistema NFT foi constituído por bancadas de telhas de fibrocimento de 1,10 x 2,44 m, considerando-se cada ondulação côncava da telha como um canal de cultivo. O transplante foi realizado em 26-04-2010, encerrando-se o experimento em 05-01-2011. Avaliaram-se a matéria fresca e seca de folhas, coroa, raízes e frutas, a área foliar, o número de frutas e o peso médio das frutas. Amostras das frutas foram analisadas em relação ao teor de sólidos solúveis totais (SST e à acidez total titulável (ATT. Com base nos resultados obtidos, conclui-se que o crescimento e a produtividade individual das plantas da cultivar de morangueiro Camino Real não são afetados pela elevação da densidade de plantio, no intervalo entre 9,3 e 15,0 plantas m-2. O crescimento e a produtividade por unidade de área, bem como a concentração de sólidos solúveis totais e a relação SST/ATT apresentam resposta linear ao incremento da densidade de plantio. Sugere-se a adoção da densidade de 12,5 plantas m-2, que proporcionaria rendimento mais elevado (2,79 kg m-2 de frutas com adequadas características organolépticas e redução no número de mudas necessárias, em relação à densidade de 15,0 plantas m-2. Existe a necessidade de desenvolver estudos adicionais com a cultivar Camino Real, a fim de promover adaptações no sistema e verificar a viabilidade econômica de seu cultivo em hidroponia.

Características agronômicas da mamoneira afetadas pelo método de condução de plantas e densidade de semeadura

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Samuel Luiz Fioreze

Full Text Available RESUMO A cultura da mamona possui grande potencial para o cultivo em condições brasileiras, contudo, deve-se buscar métodos cada vez mais eficientes de manejo da cultura, a fim de atingir altas produtividades e introduzir de modo definitivo a cultura no sistema agrícola nacional. O objetivo do presente estudo foi avaliar as características agronômicas e a produtividade da mamoneira em função do método de condução de plantas e da densidade de cultivo. O estudo foi conduzido em condições de campo no ano agrícola de 2010, utilizando a cultivar IAC 2028, em delineamento experimental de blocos casualizados em esquema fatorial 2x3 com quatro repetições. O primeiro fator foi composto por duas densidades de semeadura (26666 e 111111 plantas ha-1, enquanto o segundo fator foi composto por três métodos de condução de plantas (testemunha, poda parcial e poda+desbrota. Ao final do desenvolvimento da cultura, foram determinadas as características agronômicas das plantas, os componentes da produção e a produtividade. A poda + desbrota proporcionou melhoria dos caracteres agronômicos, sem afetar a produtividade e reduziu o ciclo da cultura em até 30 dias. Este comportamento, aliado à maturação uniforme, pode proporcionar a colheita mecanizada da cultura, além de proporcionar o cultivo da mamoneira em janelas de cultivo na safrinha, sem prejudicar a implantação da safra seguinte. O cultivo adensado de plantas de mamona limitou a emissão de ramos produtivos secundários sem afetar a produtividade, revelando elevada plasticidade fenotípica no desenvolvimento da cultura.

A hierarchical classification approach for recognition of low-density (LDPE) and high-density polyethylene (HDPE) in mixed plastic waste based on short-wave infrared (SWIR) hyperspectral imaging

Science.gov (United States)

Bonifazi, Giuseppe; Capobianco, Giuseppe; Serranti, Silvia

2018-06-01

The aim of this work was to recognize different polymer flakes from mixed plastic waste through an innovative hierarchical classification strategy based on hyperspectral imaging, with particular reference to low density polyethylene (LDPE) and high-density polyethylene (HDPE). A plastic waste composition assessment, including also LDPE and HDPE identification, may help to define optimal recycling strategies for product quality control. Correct handling of plastic waste is essential for its further "sustainable" recovery, maximizing the sorting performance in particular for plastics with similar characteristics as LDPE and HDPE. Five different plastic waste samples were chosen for the investigation: polypropylene (PP), LDPE, HDPE, polystyrene (PS) and polyvinyl chloride (PVC). A calibration dataset was realized utilizing the corresponding virgin polymers. Hyperspectral imaging in the short-wave infrared range (1000-2500 nm) was thus applied to evaluate the different plastic spectral attributes finalized to perform their recognition/classification. After exploring polymer spectral differences by principal component analysis (PCA), a hierarchical partial least squares discriminant analysis (PLS-DA) model was built allowing the five different polymers to be recognized. The proposed methodology, based on hierarchical classification, is very powerful and fast, allowing to recognize the five different polymers in a single step.

Densidad mineral ósea en una muestra de jóvenes chilenos practicantes de diversas modalidades deportivas

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Rossana Gómez-Campos

2017-01-01

Full Text Available Objetivos: Objetivos: a Comparar la densidad mineral ósea de una muestra de jóvenes chilenos practicantes de diversas modalidades deportivas y b Analizar la densidad mineral ósea en función de la maduración biológica. Métodos: Se estudiaron 146 adolescentes de sexo masculino, con un rango de edad entre 10 a 18 años. Se organizaron cinco grupos de trabajo: Grupo control (escolares n= 40, Canotaje (n= 30, Ciclismo (n=14, Fútbol (n=28 y Natación (n=34. Se evaluó el peso, estatura, altura tronco-cefálica. Se calculó el índice de Masa Corporal y la maduración biológica por medio de años de pico de velocidad de crecimiento. La densidad mineral ósea de cuerpo total y el porcentaje de grasa corporal se determinó por medio de la absorciometría de rayos X de doble energía. Resultados: Los adolescentes que practicaban fútbol evidenciaron mayor densidad mineral ósea (1,23±0,12g/cm 2 en relación a los jóvenes del ciclismo (0,99±0,11g/cm 2 , canotaje (1,09±0,17g/cm 2 , natación (1,10±0,11g/cm 2 y al grupo control de escolares (1,04±0,14g/ cm 2 (p<0.001. Hubo diferencias entre los tres niveles de maduración biológica en las cuatro modalidades deportivas y en el grupo control (p<0.001. La mayor densidad mineral ósea en función de la maduración somática se observó en los futbolistas. Conclusión: Los adolescentes que practican fútbol evidenciaron mayor densidad mineral ósea con relación a las demás modalidades deportivas y con relación al grupo control, además la maduración somática juega un papel relevante en el incremento de densidad mineral ósea, en especial en los futbolistas. Los resultados sugieren desarrollar actividades físico- deportivas de alto impacto antes, durante y después de producirse la maduración biológica en adolescentes de edad escolar.

Synthesis and thermal properties of the MA/HDPE composites with nano-additives as form-stable PCM with improved thermal conductivity

International Nuclear Information System (INIS)

Tang, Yaojie; Su, Di; Huang, Xiang; Alva, Guruprasad; Liu, Lingkun; Fang, Guiyin

2016-01-01

Highlights: • MA/HDPE composites with nano-additives were prepared for thermal conductivity enhancement. • Microstructure and chemical structure of the FSPCM were analyzed. • Thermal properties and thermal reliability of the FSPCM were investigated. • Thermal conductivity of the FSPCM can be enhanced by adding NAO and NG. - Abstract: For the purpose of improving the thermal conductivity of the form–stable phase change materials (FSPCM), two types of nano–powders with high thermal conductivity were added into the samples. In the modified FSPCM, myristic acid (MA) was used as a solid–liquid phase change material (PCM), high density polyethylene (HDPE) acted as supporting material to prevent the leakage of the melted MA. Nano–Al 2 O 3 (NAO) and nano–graphite (NG) were the additives for thermal conductivity enhancement. Scanning electronic microscope (SEM), Fourier transformation infrared spectroscope (FT–IR) and X-ray diffractometer (XRD) were used to analyze the microstructure, chemical structure and crystalline phase of the samples, respectively. Furthermore, the specific latent heat and phase transition temperature, thermal conductivity and thermal reliability were investigated using differential scanning calorimeter (DSC), thermal conductivity meter and thermo–gravimetric analyzer (TGA). The results showed that the MA was uniformly absorbed in the HDPE matrices and there was no leakage during the melting process when the mass fraction of the MA in the MA/HDPE composite was less than 70%. The DSC results revealed that the modified FSPCM have a constant phase change temperature and high specific latent heat. The thermal conductivity of the FSPCM was measured in the solid (30 °C) and liquid (60 °C) states of the MA. When the mass fraction of nano–powder additives is 12%, the thermal conductivities of the FSPCM increase by 95% (NAO) and 121% (NG) at 30 °C. It is anticipated that the FSPCM possess a potential application for thermal energy

The roles of liquid epoxidized natural rubber acrylate (LENRA) as compatibiliser in NR/HDPE blends: structural studies by electron microscopy and SANS techniques

International Nuclear Information System (INIS)

Dahlan Mohd; Mahathir Mohamed; Abdul Aziz Mohamed

2006-01-01

Further works have been carried out to determine the roles of LENRA in inducing compatibility between immiscible blends of NR/HDPE 60/40. In addition to electron microscopy images, SANS technique has been used to determine the interface thickness between the blend components. Phase-separated structures of HDPE domain embedded in NR matrix were observed by electron microscopy technique. From the results so far, the combination of 15% LENRA and 200 kGy EB radiation gives us the best Porod plot indicating the more meaningful SANS results. (Author)

Pengaruh Penambahan Cacahan Limbah Plastik Jenis High Density Polyethylene (Hdpe) Pada

OpenAIRE

Sina, Dantje A. T; Udiana, I Made; Da Costa, Bernad D

2012-01-01

Waste is a very complex problem in urban area. Plastic waste is increasing every year. Kupang with population of 291,794 people generate waste reaches 926 m3/day. Organic waste to 700 m3 and inorganic waste about 226 m3. Concrete is planned by strength quality 25 MPa. Based on the analysis in this study obtained that concrete flexural strength value increased due to the addition of HDPE plastic shredded into the concrete, with chopped levels are added to the concrete at 0%, 0.50% and 0.90...

Installing a HDPE vertical containment and collection system in one pass utilizing a deep trencher

International Nuclear Information System (INIS)

Bocchino, W.M.; Burson, B.

1997-01-01

A unique method has been developed to install high density polyethylene (HDPE) vertical containment panels and a horizontal collection system for the containment and collection of contaminated groundwater. Unlike other means of creating this type of system, this barrier wall and collection system is installed in one step and in one narrow trench, utilizing a one-pass deep trencher. Originally HDPE vertical barriers were installed using conventional slurry trenching techniques. Use of this method raised questions of trench stability and disposal costs for the trench spoils. In addition, if a collection system was desired, a separate trench or vertical wells were required. In response to these concerns, a trenchless vibratory installation method was developed. Although this method addressed the concerns of trench stability and disposal costs, it raised a whole new set of concerns dealing with drivable soil conditions, buried debris and obstructions. Again, if a collection system was desired, a separate trench or vertical wells had to be installed. The latest development, the one-pass, deep trencher, has eliminated or significantly reduced the previously discussed construction concerns. The trencher methods reduce the amount of spoils generated because a trench width of 61 cm (24 inches) is constantly maintained by the machine. Additionally, soil classification and density are not as critical as with a vibratory installation. This is due to the trencher's ability to trench in all but the hardest of materials (blow counts exceeding 35 blows/ft). Finally, the cost to add a collection system adjacent to the cutoff wall is substantially reduced and is limited only to the cost of the additional hydraulic fill and 4 inches HDPE collection piping. The trench itself is already constructed with the installation of the wall

Effect of n-3 polyunsaturated fatty acids on the lipidic profile of healthy Mexican volunteers Efecto de los ácidos grasos polinsaturados n-3 en el perfil lipídico de mexicanos voluntarios

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OCTAVIO CARVAJAL

1997-05-01

Full Text Available Objective. The effect of n-3 polyunsaturated fatty acids on the serum lipid profile in a Mexican population was evaluated. Material and methods. Three g of salmon oil was the daily intake during four weeks. Total cholesterol, triglycerides, low density lipoproteins, high density lipoproteins and erythrocyte fatty acid composition were analyzed. Results. The hypertriglyceridemic group showed a statistically significant (pObjetivo. Estudiar el efecto de los ácidos grasos polinsaturados n-3 en el perfil lipídico sérico de una población mexicana. Material y métodos. La ingesta diaria del suplemento de aceite de salmón fue de 3 gramos durante cuatro semanas. Se evaluaron los niveles de colesterol total, triglicéridos, lipoproteínas de baja densidad, lipoproteínas de alta densidad y la composición en ácidos grasos de los eritrocitos. Resultados. Muestran una reducción significativa (p< 0.05 en los niveles de triglicéridos y un aumento significativo (p< 0.01 en los niveles de lipoproteínas de alta densidad en los sujetos con hipertrigliceridemia. El grupo con hipercolesterolemia presentó reducción en los niveles de colesterol total y triglicéridos y aumento significativo en los niveles de lipoproteínas de alta densidad (p< 0.01. Conclusiones. El efecto hipolipidemiante de los ácidos grasos polinsaturados n-3 se puso de manifiesto en voluntarios mexicanos bajo las condiciones aquí evaluadas.

Avaliação da densidade populacional e regeneração natural do palmito juçara (Euterpe edulis Mart. no município de São João Evangelista-MG

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Paulo do Nascimento

2015-07-01

Full Text Available Este trabalho foi desenvolvido em uma população de E. edulis (palmito juçara em uma área de 4.5 hectares da fazenda Nova Granja de 363 hectares, em São João Evangelista, MG. Objetivou-se analisar a estrutura populacional dessa espécie em Floresta Estacional Semidecidual Montana, compreender sua dinâmica e contribuir com informações  sobre o manejo sustentado de E. edulis nesse tipo de ambiente. Os dados da população foram coletados em 10 parcelas de 10 x 15 m, alocadas em três transectos dispostos em nordeste-sudoeste, com 175 m de distância entre si. Coletaram-se dados referentes a cinco estádios de desenvolvimento (Jovem I, Jovem II, Imaturo I, Imaturo II e Adulto e avaliaram-se a densidade e a regeneração dessa população. Foi encontrado grande percentual de Jovem I. Adultos com altura de inserção foliar entre 14,3 e 18,3 m foram a classe mais frequente nessa população. A densidade populacional apresentou-se relativamente alta (0,74/m2; a população possui distribuição em “J” invertido, sendo uma população em estado natural de conservação. Palavras-chave: Palmeira juçara. “J” invertido. Arecaceae.

Effect of Boron and Phosphate compounds on Thermal and Fire Properties of wood/HDPE composites

Science.gov (United States)

Turgay Akbulut; Nadir Ayrilmis; Turker Dundar; Ali Durmus; Robert H. White; Murat Teker

2011-01-01

Melting and non-isothermal crystallization behaviors, oxidative induction time, and fire performance of the injection-molded wood flour-high density polyethylene (HDPE) composites (WPCs) incorporated with different levels (4, 8, or 12 wt %) of boron compounds [borax/boric acid (BX/BA) (0.5:0.5 wt %), zinc borate (ZB)] and phosphorus compounds [mono- and di-ammonium...

Densidad, estructura de tallas y actividad reproductiva del caracol rosado Eustrombus gigas (Mesogastropoda: Strombidae en Banco Chinchorro, México

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Yuself R Cala

2013-12-01

Full Text Available Eustrombus gigas es uno de los recursos pesqueros costeros más valiosos en la región del Caribe y constituye un molusco con un elevado valor estético y ecológico. En esta investigación se evalúa su densidad total, densidad de adultos, la estructura de tallas y frecuencia de evidencias reproductivas en Banco Chinchorro, México, periodo 2009-2010; durante tres períodos (de lluvias, seca y de frentes fríos en tres zonas: Norte, Centro y Sur. La densidad total para el área de estudio varió de 127ind./ha en lluvias a 384ind./ha en seca, la menor densidad se presentó en la zona Norte del Banco (198ind./ha y la mayor en la zona Sur (385ind./ha. La densidad de caracoles adultos fue baja (6.11ind./ha en seca y 8.33ind./ha en lluvias y 5.55, 7.05 y 8.33ind./ha para las zonas Centro, Sur y Norte, respectivamente. Las densidades de adultos estuvieron por debajo del umbral mínimo necesario para mantener la reproducción. El 42% de la población es vulnerable a la pesca (Lsi≥200mm; sin embargo, solo 2.2% de la población alcanza un Gl>15mm. Solo se observaron seis evidencias de reproducción durante el período de estudio, lo que señala la presencia del efecto Allee en la población y la urgente necesidad del cierre de su pesquería. Se proponen tres puntos importantes para el manejo de la especie: cierre de la pesca, monitoreo de la población y la implementación refugios pesqueros

The extrudate swell of HDPE: Rheological effects

Science.gov (United States)

Konaganti, Vinod Kumar; Ansari, Mahmoud; Mitsoulis, Evan; Hatzikiriakos, Savvas G.

2017-05-01

The extrudate swell of an industrial grade high molecular weight high-density polyethylene (HDPE) in capillary dies is studied experimentally and numerically using the integral K-BKZ constitutive model. The non-linear viscoelastic flow properties of the polymer resin are studied for a broad range of large step shear strains and high shear rates using the cone partitioned plate (CPP) geometry of the stress/strain controlled rotational rheometer. This allowed the determination of the rheological parameters accurately, in particular the damping function, which is proven to be the most important in simulating transient flows such as extrudate swell. A series of simulations performed using the integral K-BKZ Wagner model with different values of the Wagner exponent n, ranging from n=0.15 to 0.5, demonstrates that the extrudate swell predictions are extremely sensitive to the Wagner damping function exponent. Using the correct n-value resulted in extrudate swell predictions that are in excellent agreement with experimental measurements.

The ALTA global positioning satellite based timing system

CERN Document Server

Brouwer, W; Caron, B; Hewlett, J C; Holm, L; Hamilton, A H; McDonald, W J; Pinfold, J L; Schaapman, J R; Soluk, R A; Wampler, L J

2002-01-01

The Alberta Large-area Time-coincidence Array (ALTA) experiment uses a number of scintillation detector systems to form a sparse very large area cosmic air-shower detection array. An important scientific goal of the ALTA collaboration is to search for coincidences in the ALTA array due to large area cosmic ray phenomena. A local cosmic ray event, determined by a coincidence of the triplet of cosmic ray detectors forming a local detector system, is time stamped with a temporal coordinate obtained from a GPS receiver. The readout of the data, the local coincidence and the GPS time stamp are all performed in the local readout crate. This time stamp, along with the local shower direction is used to search for coincidences within the large area array. Using two GPS receivers and duplicate sets of ALTA electronics the timing resolution of the GPS time difference between sites was estimated to be 16 ns.

Thermal, tensile and rheological properties of high density polyethylene (HDPE) processed and irradiated by gamma-ray in different atmospheres

Energy Technology Data Exchange (ETDEWEB)

Ferreto, H. F. R., E-mail: hferreto@ipen.br, E-mail: ana-feitoza@yahoo.com.br; Oliveira, A. C. F., E-mail: hferreto@ipen.br, E-mail: ana-feitoza@yahoo.com.br; Parra, D. F., E-mail: dfparra@ipen.br, E-mail: ablugao@ipen.br; Lugão, A. B., E-mail: dfparra@ipen.br, E-mail: ablugao@ipen.br [Center of Chemistry and Environment, Institute of Energy and Nuclear Research - IPEN (Brazil); Gaia, R., E-mail: renan-gaia7@hotmail.com [Faculdades Oswaldo Cruz (Brazil)

2014-05-15

The aim of this paper is to investigate structural changes of high density polyethylene (HDPE) modified by ionizing radiation (gamma rays) in different atmospheres. The gamma radiation process for modification of commercial polymers is a widely applied technique to promote new physical-chemical and mechanical properties. Gamma irradiation originates free radicals which can induce chain scission or recombination, providing its annihilation, branching or crosslinking. This polymer was irradiated with gamma source of {sup 60}Co at doses of 5, 10, 20, 50 or 100 kGy at a dose rate of 5 kGy/h. The changes in molecular structure of HDPE, after gamma irradiations were evaluated using thermogravimetric analysis (TGA) and tensile machine and oscillatory rheology. The results showed the variations of the properties depending on the dose at each atmosphere.

Effect of wood flour content on the optical color, surface chemistry, mechanical and morphological properties of wood flour/recycled high density polyethylene (rHDPE) composite

Science.gov (United States)

Sheng, Chan Kok; Amin, Khairul Anuar Mat; Kee, Kwa Bee; Hassan, Mohd Faiz; Ali, E. Ghapur E.

2018-05-01

In this study, effect of wood flour content on the color, surface chemistry, mechanical properties and surface morphology of wood-plastic composite (WPC) on different mixture ratios of recycled high density polyethylene (rHDPE) and wood flour were investigated in detail. The presence of wood flour in the composite indicates a significant total color change and a decrease of lightness. Functional groups of wood flour in WPC can be seen clearer from the Fourier transform infrared (FTIR) spectra as the wood flour content increases. The mechanical tensile testing shows that the tensile strength of Young's modulus is improved, whereas the strain and elongation at break were reduced by the addition of wood flour. The gap between the wood flour microvoid fibre and rHDPE matrix becomes closer when the wood flour content is increased as observed by scanning electron microscope (SEM) image. This finding implies a significant improvement on the interaction of interfacial adhesion between the rHDPE matrix and wood flour filler in the present WPC.

EFECTO DEL RALEO SOBRE EL CRECIMIENTO Y LA DENSIDAD DE LA MADERA DE Pinus taeda IMPLANTADO EN MISIONES, ARGENTINA

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Rodolfo Martiarena

2014-09-01

Full Text Available http://dx.doi.org/10.5902/1980509815746El mayor incremento en crecimiento de la plantación puede causar variación en las propiedades físicas de la madera, pudiendo disminuir la calidad de la misma para la industria. El objetivo del presente trabajo es evaluar el efecto de los tratamientos de raleo sobre el crecimiento y densidad de la madera de Pinus taeda implantado en Misiones, Argentina (25º 59’S - 54º24’O. La plantación se estableció en 1985 con densidad inicial de 1644 pl.ha-1y se manejó con tres intensidades de raleo (0, 33 y 66 % del área basal del testigo sin ralear, bajo un diseño de bloques completos al azar (3 bloques. A los 20 años se efectuó tala rasa, cuyas densidades eran 711 (0 %, 364 (33 % y 122 (66 % plantas por hectárea, momento en el cual se seleccionaron 45 árboles para determinar la densidad básica de la madera. La misma se determinó a través de la realización de 2.700 probetas. El crecimiento de la plantación fue afectado por la intensidad de raleo, registrando diámetros promedio de 28,7, 34,8 y 45,9 cm, respectivamente, en los tratamientos 0, 33 y 66 % de raleo. El volumen de la plantación, al momento del apeo, fue superior en el tratamiento sin raleo, no obstante el tratamiento 66 % de raleo generó mayor cantidad de madera de grandes dimensiones. La densidad básica como promedio simple y ponderado por volumen no presentó diferencias significativas entre tratamientos. Los valores de densidad ponderada fueron de 0,406, 0,418 y 0,420 g.cm-3 para los tratamientos 0, 33 y 66 % de raleo, respectivamente, mientras que el análisis de correlación entre diámetro y densidad no fue significativo. El estudio mostró que la intensidad de raleo puede ser manejada para maximizar la producción, manteniendo idéntica la calidad de la madera para la industria.

EFECTO DEL RALEO SOBRE EL CRECIMIENTO Y LA DENSIDAD DE LA MADERA DE Pinus taeda IMPLANTADO EN MISIONES, ARGENTINA

Directory of Open Access Journals (Sweden)

Rodolfo Martiarena

2014-01-01

Full Text Available El mayor incremento en crecimiento de la plantación puede causar variación en las propiedades físicas de la madera, pudiendo disminuir la calidad de la misma para la industria. El objetivo del presente trabajo es evaluar el efecto de los tratamientos de raleo sobre el crecimiento y densidad de la madera de Pinus taeda implantado en Misiones, Argentina (25º 59’S - 54º24’O. La plantación se estableció en 1985 con densidad inicial de 1644 pl.ha -1 y se manejó con tres intensidades de raleo (0, 33 y 66 % del área basal del testigo sin ralear, bajo un diseño de bloques completos al azar (3 bloques. A los 20 años se efectuó tala rasa, cuyas densidades eran 711 (0 %, 364 (33 % y 122 (66 % plantas por hectárea, momento en el cual se seleccionaron 45 árboles para determinar la densidad básica de la madera. La misma se determinó a través de la realización de 2.700 probetas. El crecimiento de la plantación fue afectado por la intensidad de raleo, registrando diámetros promedio de 28,7, 34,8 y 45,9 cm, respectivamente, en los tratamientos 0, 33 y 66 % de raleo. El volumen de la plantación, al momento del apeo, fue superior en el tratamiento sin raleo, no obstante el tratamiento 66 % de raleo generó mayor cantidad de madera de grandes dimensiones. La densidad básica como promedio simple y ponderado por volumen no presentó diferencias significativas entre tratamientos. Los valores de densidad ponderada fueron de 0,406, 0,418 y 0,420 g.cm -3 para los tratamientos 0, 33 y 66 % de raleo, respectivamente, mientras que el análisis de correlación entre diámetro y densidad no fue significativo. El estudio mostró que la intensidad de raleo puede ser manejada para maximizar la producción, manteniendo idéntica la calidad de la madera para la industria.

Data characterizing tensile behavior of cenosphere/HDPE syntactic foam.

Science.gov (United States)

Kumar, B R Bharath; Doddamani, Mrityunjay; Zeltmann, Steven E; Gupta, Nikhil; Ramakrishna, Seeram

2016-03-01

The data set presented is related to the tensile behavior of cenosphere reinforced high density polyethylene syntactic foam composites "Processing of cenosphere/HDPE syntactic foams using an industrial scale polymer injection molding machine" (Bharath et al., 2016) [1]. The focus of the work is on determining the feasibility of using an industrial scale polymer injection molding (PIM) machine for fabricating syntactic foams. The fabricated syntactic foams are investigated for microstructure and tensile properties. The data presented in this article is related to optimization of the PIM process for syntactic foam manufacture, equations and procedures to develop theoretical estimates for properties of cenospheres, and microstructure of syntactic foams before and after failure. Included dataset contains values obtained from the theoretical model.

Comparación de las densidades de Annelida en diferentes paisajes de la Amazonía colombiana

Directory of Open Access Journals (Sweden)

Miguel Antonio Molano Molano

2006-01-01

de Tarapacá, la correlación se presentó con: la humedad, densidad aparente, y porosidad. Se infiere de las observaciones realizadas en las zonas donde se efectuaron los muestreos que la densidad de Annelida esta influenciada más por el uso al que es sometido el suelo que por el tipo de paisaje donde éste se encuentra. Adicionalmente, se reporta la presencia de Hirudinida en tres sitios diferentes, dentro del perfil edáfico.

Expansión estacionaria del plasma producido por un pulso de láser sobre una microesfera

OpenAIRE

Sanz Recio, Javier

1981-01-01

Para obtener energía de fusión mediante el láser, es necesario comprimir una microesfera a densidades muy altas (diez mil veces la densidad inicial), calentando al mismo tiempo un pequeño núcleo central del blanco a temperaturas del orden de 10 KeV. El problema queda dividido en dos partes bien diferenciadas cuando existe una superficie de ablación que separa el problema interior que es no estacionario y el problema exterior,, el cual se puede tomar cuasi estacionario si la densidad crítica d...

Comportamento de poedeiras criadas a diferentes densidades e tamanhos de grupo em ambiente enriquecido

Directory of Open Access Journals (Sweden)

Danilo Florentino Pereira

2013-06-01

Full Text Available O objetivo deste trabalho foi determinar diferenças comportamentais entre poedeiras criadas sob diferentes densidades e tamanhos de grupo, em condições de ambiente enriquecido. Foram utilizadas poedeiras Isa Brown com idade entre 30 e 32 semanas alojadas em galpões de escala reduzida e distorcida. As aves foram criadas durante 28 dias, em baias com cama de maravalha, poleiro e ninho. Foram avaliados dois tamanhos de grupos (6 e 12 aves e duas densidades de criação (774 e 1.440 cm² por ave, em arranjo fatorial com três repetições. Em amostras de vídeo de 15 min, foram registrados as frequências e os tempos de expressão dos comportamentos: arrumar penas, banho de areia, bater asas, beber água, bicar, coçar a cabeça, ciscar, comer, empoleirar, esticar perna, perseguir, sentar e visitar o ninho. Foram observados efeitos significativos dos tratamentos e da interação entre eles. O grupo de seis aves manifestou aumento da frequência de comportamentos que indicam maior frustração das aves, independentemente da densidade. O tamanho de grupo é o fator mais importante para o bem-estar das aves.

Effect of fiber orientation on tensile and impact properties of Zalacca Midrib fiber-HDPE composites by compression molding

Science.gov (United States)

Lasikun, Ariawan, Dody; Surojo, Eko; Triyono, Joko

2018-02-01

The research aims to investigate the fiber orientation effect on the tensile and impact properties of zalacca midrib fiber /HDPE composites. The composites were produced by compression molding with pressing temperature at 150°C, pressing pressure at 50 bar, and holding time of 25 minutes. The fiber orientations applied in composites were 0°, 15°, 30°, 45°, 60°, 75°, and 90°, at 10% fiber volume fraction. The samples were evaluated by using: Tensile test and Izod impact test according to ASTM D638 and ASTM D5941, respectively. The result of experiments indicate that the orientation of zalacca midrib fiber influences the characteristics of HDPE composite-zalacca midrib fiber. The composite mechanical strength decline with the increase of orientation fibers from 0° to 90°. The composite failure mode of composites are observed by Scanning Electron Microscope (SEM).

The ALTA cosmic ray experiment electronics system

International Nuclear Information System (INIS)

Brouwer, W.; Burris, W.J.; Caron, B.; Hewlett, J.; Holm, L.; Hamilton, A.; McDonald, W.J.; Pinfold, J.L.; Price, P.; Schaapman, J.R.; Sibley, L.; Soluk, R.A.; Wampler, L.J.

2005-01-01

Understanding the origin and propagation of high-energy cosmic rays is a fundamental area of astroparticle physics with major unanswered questions. The study of cosmic rays with energy more than 10 14 eV, probed only by ground-based experiments, has been restricted by the low particle flux. The Alberta Large-area Time-coincidence Array (ALTA) uses a sparse array of cosmic ray detection stations located in high schools across a large geographical area to search for non-random high-energy cosmic ray phenomena. Custom-built ALTA electronics is based on a modular board design. Its function is to control the detectors at each ALTA site allowing precise measurements of event timing and energy in the local detectors as well as time synchronization of all of the sites in the array using the global positioning system

LA DENSIDAD Y TAMAÑO DE PLÁNTULAS CON CEPELLÓN EN LA PRODUCCIÓN DE ESPÁRRAGO VERDE

OpenAIRE

Ana Mar\\u00EDa Castagnino; Karina Elizabeth D\\u00EDaz; Patricia Sastre V\\u00E1zquez; Mar\\u00EDa Bel\\u00E9n Rosini; Silvina Sasale

2011-01-01

La densidad y tamaño de plántulas con cepellón en la producción de espárrago verde. Con el objetivo de determinar la influencia del tamaño de la celda utilizada para la obtención de plántulas de espárrago y la densidad o marco de plantación empleado, sobre la producción de turiones, se evaluó en invernadero tres tamaños de celda: 1) PG: grande (70 cm³), 2) PM: mediana (30 cm³) y 3) PCh: pequeña (20 cm³) y tres densidades (35 714 (D1); 23 810 (D2) y 17 857 (D3) plantas/ha). Se efectuó un traba...

TransAlta Corporation 1996 annual report : new directions, new opportunities

International Nuclear Information System (INIS)

Anon.

1997-01-01

TransAlta Corp. is an energy management company that operates through two subsidiaries: (1) TransAlta Utilities Corp. which owns and operates electricity generation, transmission and distribution assets in Alberta, and (2) TransAlta Energy Corp. which is in the business of electric and thermal energy supply, gas and electricity distribution, energy services and energy marketing in regions of Canada, New Zealand, Australia, Argentina and the United States. This report presents a summary of operations, and provides consolidated financial statements and common share information for 1996. During the year the corporation advanced three significant initiatives (1) operational effectiveness, as shown by impressive productivity increases, and major investments in three independent power projects, (2) improved strategic direction through a review of plans and options, resulting in a clearer, more focused vision of the future, and (3) realignment of the organizational structure by centralizing marketing and sales functions, and establishing a corporate business development group. Details of operational and financial results were provided for both subsidiaries, i. e. TransAlta Utilities and TransAlta Energy. Sales of electric energy for TransAlta Utilities amounted to 27.8 billion kWh; 4.6 billion kWh for TransAlta Energy. Return on equity was 11.4 per cent, down from 11.8 per cent in 1995. Net earnings per common share were $1.14 per share (including one-time items), the same as in 1995. tabs., figs

A Taguchi approach on optimal process control parameters for HDPE pipe extrusion process

Science.gov (United States)

Sharma, G. V. S. S.; Rao, R. Umamaheswara; Rao, P. Srinivasa

2017-06-01

High-density polyethylene (HDPE) pipes find versatile applicability for transportation of water, sewage and slurry from one place to another. Hence, these pipes undergo tremendous pressure by the fluid carried. The present work entails the optimization of the withstanding pressure of the HDPE pipes using Taguchi technique. The traditional heuristic methodology stresses on a trial and error approach and relies heavily upon the accumulated experience of the process engineers for determining the optimal process control parameters. This results in setting up of less-than-optimal values. Hence, there arouse a necessity to determine optimal process control parameters for the pipe extrusion process, which can ensure robust pipe quality and process reliability. In the proposed optimization strategy, the design of experiments (DoE) are conducted wherein different control parameter combinations are analyzed by considering multiple setting levels of each control parameter. The concept of signal-to-noise ratio ( S/ N ratio) is applied and ultimately optimum values of process control parameters are obtained as: pushing zone temperature of 166 °C, Dimmer speed at 08 rpm, and Die head temperature to be 192 °C. Confirmation experimental run is also conducted to verify the analysis and research result and values proved to be in synchronization with the main experimental findings and the withstanding pressure showed a significant improvement from 0.60 to 1.004 Mpa.

White HDPE bottles as source of serious contamination of water samples with Ba and Zn.

Science.gov (United States)

Reimann, Clemens; Grimstvedt, Andreas; Frengstad, Bjørn; Finne, Tor Erik

2007-03-15

During a recent study of surface water quality factory new white high-density polyethylene (HDPE) bottles were used for collecting the water samples. According to the established field protocol of the Geological Survey of Norway the bottles were twice carefully rinsed with water in the field prior to sampling. Several blank samples using milli-Q (ELGA) water (>18.2 MOmega) were also prepared. On checking the analytical results the blanks returned values of Ag, Ba, Sr, V, Zn and Zr. For Ba and Zn the values (c. 300 microg/l and 95 microg/l) were about 10 times above the concentrations that can be expected in natural waters. A laboratory test of the bottles demonstrated that the bottles contaminate the samples with significant amounts of Ba and Zn and some Sr. Simple acid washing of the bottles prior to use did not solve the contamination problem for Ba and Zn. The results suggest that there may exist "clean" and "dirty" HDPE bottles depending on manufacturer/production process. When collecting water samples it is mandatory to check bottles regularly as a possible source of contamination.

Impact of landfill liner time-temperature history on the service life of HDPE geomembranes.

Science.gov (United States)

Rowe, R Kerry; Islam, M Z

2009-10-01

The observed temperatures in different landfills are used to establish a number of idealized time-temperature histories for geomembrane liners in municipal solid waste (MSW) landfills. These are then used for estimating the service life of different HDPE geomembranes. The predicted antioxidant depletion times (Stage I) are between 7 and 750 years with the large variation depending on the specific HDPE geomembrane product, exposure conditions, and most importantly, the magnitude and duration of the peak liner temperature. The higher end of the range corresponds to data from geomembranes aged in simulated landfill liner tests and a maximum liner temperature of 37 degrees C. The lower end of the range corresponds to a testing condition where geomembranes were immersed in a synthetic leachate and a maximum liner temperature of 60 degrees C. The total service life of the geomembranes was estimated to be between 20 and 3300 years depending on the time-temperature history examined. The range illustrates the important role that time-temperature history could play in terms of geomembrane service life. The need for long-term monitoring of landfill liner temperature and for geomembrane ageing studies that will provide improved data for assessing the likely long-term performance of geomembranes in MSW landfills are highlighted.

Finite Element Analysis of Patella Alta: A Patellofemoral Instability Model.

Science.gov (United States)

Watson, Nicole A; Duchman, Kyle R; Grosland, Nicole M; Bollier, Matthew J

2017-01-01

This study aims to provide biomechanical data on the effect of patella height in the setting of medial patellofemoral ligament (MPFL) reconstruction using finite element analysis. The study will also examine patellofemoral joint biomechanics using variable femoral insertion sites for MPFL reconstruction. A previously validated finite element knee model was modified to study patella alta and baja by translating the patella a given distance to achieve each patella height ratio. Additionally, the models were modified to study various femoral insertion sites of the MPFL (anatomic, anterior, proximal, and distal) for each patella height model, resulting in 32 unique scenarios available for investigation. In the setting of patella alta, the patellofemoral contact area decreased, resulting in a subsequent increase in maximum patellofemoral contact pressures as compared to the scenarios with normal patellar height. Additionally, patella alta resulted in decreased lateral restraining forces in the native knee scenario as well as following MPFL reconstruction. Changing femoral insertion sites had a variable effect on patellofemoral contact pressures; however, distal and anterior femoral tunnel malpositioning in the setting of patella alta resulted in grossly elevated maximum patellofemoral contact pressures as compared to other scenarios. Patella alta after MPFL reconstruction results in decreased lateral restraining forces and patellofemoral contact area and increased maximum patellofemoral contact pressures. When the femoral MPFL tunnel is malpositioned anteriorly or distally on the femur, the maximum patellofemoral contact pressures increase with severity of patella alta. When evaluating patients with patellofemoral instability, it is important to recognize patella alta as a potential aggravating factor. Failure to address patella alta in the setting of MPFL femoral tunnel malposition may result in even further increases in patellofemoral contact pressures, making it

Amine modified polyethylenes, prepared in near critical propane, as adhesion promoting agents in multilayered HDPE/PET films

NARCIS (Netherlands)

Gooijer, de J.M.; Scheltus, M.; Koning, C.E.

2001-01-01

High d. polyethylene (HDPE) grafted with 0.13, 0.40 and 1.04 wt% maleic anhydride (abbreviation PEMA) was modified with an excess of a variety of diamines in near crit. propane. The resulting amic acid groups were quant. imidized to the corresponding imide (PEMI) in the melt. Increasing the

Criatividade e altas habilidades/superdotação

Directory of Open Access Journals (Sweden)

Denise de Souza Fleith

2011-11-01

Full Text Available Identificar e estimular a criança com altas habilidades/superdotação tem se constituído em um desafio para educadores e psicólogos. Muitas concepções acerca do fenômeno das altas habilidades têm sido propostas por estudiosos desde o início do século XX. Uma das concepções mais conhecidas sobre o superdotado é de que seria aquele indivíduo que se sai bem nos testes de inteligência, ou que apresenta um desempenho intelectual superior. Entretanto, superdotação não pode ser considerada exclusivamente como sinônimo de QI alto. Concepções atuais sobre este fenômeno têm chamado a atenção para a importância de se considerar outros aspectos como influência do ambiente, sorte, autoconceito positivo, motivação e, especialmente, a criatividade. Dois importantes objetivos da educação do aluno com altas habilidades/superdotação são: (a desenvolver talentos e habilidades, auxiliando estes indivíduos a atualizarem seu potencial e se tornarem criativos, e (b habilitá-los a darem contribuições criativas à sociedade. O objetivo deste artigo é, portanto, discutir a importância da criatividade no desenvolvimento de altas habilidades/superdotação. Palavras-chave: Superdotação. Altas Habilidades. Criatividade. Inteligência.

Gas-phase and liquid-phase pre-irradiation grafting of AAc onto LDPE and HDPE films for pervaporation membranes

International Nuclear Information System (INIS)

Rao Zhigong; Li Guixiang; Sugo, Takanobu; Okamoto, Jiro

1992-01-01

A study has been made on gas-phase and liquid-phase pre-irradiation grafting of acrylic acid onto LDPE and HDPE films for pervaporation membranes of ethanol-water mixtures. It was found that the degree of grafting, percent volume change of grafted membranes and length of grafting chains depend on the methods of grafting, crystal state of substrate films and diffusion rate of the monomer in the films. The pervaporation characteristics of grafted membranes is influenced directly by the surface hydrophilicity of grafted membranes, temperature of the feed, degree of grafting, crosslinking of grafted chains and alkaline metal ions in the functional groups. The potassium ion exchange membrane of HDPE synthesized by gas-phase grafting has better pervaporation efficiency. At 80 wt% ethanol in the feed, 25 o C feed temperature and 70% degree of grafting a grafted membrane has a 0.65 kg/m 2 h flux and a separation factor of 20. (Author)

Comparative study of three different kinds of geomembranes (PVC-P, HDPE, EPDM) used in the waterproofing of reservoirs

International Nuclear Information System (INIS)

Blanco Fernandez, M.; Castillo Rubi, F.; Soriano Carrillo, J.; Noval Arango, A. M.; Touze-Foltz, N.; Pargada Iglesias, L.; Rico Arnaiz, G.; Aguilar gonzalez, E.

2014-01-01

This work describes the long-term behaviour of three kinds of geomembranes which are constituted by plasticized poly vinyl chloride (PVC-P), high density polyethylene (HDPE) and terpolymer rubber of ethylene-propylene-dienic monomer (EPDM) used as the waterproofing system of the reservoirs Los Llanos de Mesa, San Isidro and El Golfo, respectively. Characteristics of the three original geomembranes and their behaviour along time are presented. Thicknesses, content and nature of the plasticizers ( in PVC-P), tensile properties dynamic and static puncture, foldability at low temperature, shore hardeness, tear resistance and carbon black ( in HDPE), joint strength (shear and peeling test) and microscopy, both optical and electronic scanning tests were carried out. Results obtained conclude with a long-term durability of geomembranes, independently of their macromolecular nature. These characteristics were determined by advanced analytical techniques in PVC-P samples, such as fourier Transform Infrared Spectroscopy (FTIR), Gas Chromatography (GC) and Mass Spectrometry (MS). Spectrometry (MS). (Author)

Fluidized bed pyrolysis of HDPE: A study of the influence of operating variables and the main fluid dynamic parameters on the composition and production of gases

Energy Technology Data Exchange (ETDEWEB)

Martinez, Lidia; Aguado, Alicia; Moral, Alberto [CARTOF Centro Tecnologico, Valladolid (Spain). Environmental Div.; Irusta, Ruben [CARTOF Centro Tecnologico, Valladolid (Spain). Environmental Div.; Valladolid Univ. (Spain). Dept. of Chemical Engineering and Environmental Technology

2011-02-15

In the present work, a preliminary study of the pyrolysis process of high density polyethylene (HDPE) in a fluidized bed is investigated in order to determine the influence between the fluid dynamic properties of the bed reactor and the amount and composition of the gases produced. As is known, fluidized bed technology is a very interesting option to apply in the pyrolysis field due to i) the lack of moving parts in the hot region that facilitates the maintenance of equipment, ii) the high surface area to volume ratio available in the bed, and iii) the high heat transfer coefficient reached which governs the reaction products. But, heat and mass transfer coefficients are strongly affected by the fluid dynamic properties of the bed. During the pyrolysis of HDPE, a fluid dynamic characterization of the bed particles that consist of char-coated sand of HDPE has been carried out. Parameters such as the minimum fluidizing velocity (u{sub mf}), terminal velocity (u{sub t}), bed height (h{sub f}), bed voidage ({epsilon}{sub f}), fraction of the bed occupied by bubbles ({delta}), bubble diameter (d{sub b}), bubble velocity (u{sub b}), the mass transfer coefficients between the bubble and the cloud (K{sub bc}) and between the cloud and the emulsion (K{sub ce}) were determined. Subsequently, the influence of major operating variables and the fluid dynamic parameters on the composition and the gas yield of the pyrolysis of HDPE were studied. (author)

Caracterización morfométrica de la cuenca alta del río Sauce Grande.

Directory of Open Access Journals (Sweden)

Fernanda Julia Gaspari

2013-01-01

Full Text Available La cuenca alta del río Sauce Grande abastece el complejo hidráulico Embalse Paso de las Piedras, comportándose como servicio ambiental primordial para el consumo hídrico de Bahía Blanca. El análisis de las características morfométricas y funcionales de una cuenca hidrográfica a través de parámetros de forma, relieve y red de drenaje, es básico en la modelación hidrológica para determinar el movimiento y captación del agua de lluvia. Estos indicadores pueden apoyar una formulación de un Sistema de Pago por Servicios Ambientales, como estrategia básica de ordenamiento territorial y desarrollo local, centrado en la oferta de agua generada por la cuenca. El objetivo fue caracterizar morfométricamente la cuenca alta del río Sauce Grande. La metodología aplicada se basó en establecer y analizar los parámetros morfométricos mediante el uso de Sistemas de Información Geográfica y planillas de cálculo, a partir de un modelo digital del terreno e imágenes satelitales. Los resultados alcanzados definieron que la cuenca posee un área de 1502.6 km2. La longitud axial es de 41.6 km con un ancho promedio de 36.1 km. El Factor de forma (0.87 indica que posee forma alargada, siendo rectangular oblonga según el coeficiente de compacidad de Gravelius (2.8. La longitud del cauce principal es 58.34 km con pendiente media de 0.48 %. La densidad de drenaje es 0.27 km.km-2 y su coeficiente de sinuosidad 1.42. El tiempo de concentración es 11.8 hs. La curva hipsométrica adimensional corresponde a una cuenca con un avanzado grado de desarrollo. Todos estos parámetros facilitan la cuantificación del caudal líquido en la cuenca.

Shear and elongational rheology of photo-oxidative degraded HDPE and LLDPE

Science.gov (United States)

Wagner, Manfred Hermann; Zheng, Wang; Wang, Peng; Talamante, Sebastián Ramos; Narimissa, Esmaeil

2017-05-01

The effect of photo-oxidative degradation of high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE) was investigated by linear and non-linear rheological measurements. The linear-viscoelastic rheological measurements were performed at different temperatures, while the elongational viscosity was measured at 170°C and at different strain rates. The rheological data are indicative of structural changes caused by photo-oxidative degradation including formation of long-chain branches (LCB), cross-linking, and chain scission, and they revealed a cyclic and continuing competition between chain scission and LCB/gel formation. These findings are supported by additional FTIR measurements and direct measurements of the gel content of the degraded samples.

Effect of liquid epoxidized natural rubber (LENR) on mechanical properties and morphology of natural rubber/high density polyethylene/mengkuang fiber (NR/HDPE/MK) bio-composite

Science.gov (United States)

Piah, Mohd Razi Mat; Baharum, Azizah

2016-11-01

The use of mengkuang fiber (MK) fibers in NR/HDPE (40/60) blend was studied via surface modification of fiber. The MK fiber was pre-washed with 5%wt/v sodium hydroxide solution prior to treatment with liquid epoxidized natural rubber (LENR). The concentration of LENR were varied from 5%-20%wt in toluene. The effects of LENR concentrations were studied in terms of mechanical properties and morphology formed. Melt-blending was performed using an internal mixer (Haake Rheomix 600). The processing parameters identified were 135°C temperature, 45 rpm rotor speed, 12 minutes processing time and at 20%wt MK fiber loading. The optimum LENR treatment concentration was obtained at 5%wt with tensile strength, tensile modulus, and impact strength of 10.3 MPa, 414.2 MPa and 14.4 kJ/m2 respectively. The tensile modulus of LENR-treated MK fiber filled NR/HDPE bio-composite has shown enhancement up to 16.7% higher than untreated MK fiber. The tensile and impact strength were decreased with increasing LENR concentration due to the broken of MK fibers to smaller particles and adhered to each other. FESEM micrographs confirmed the formation of fiber-fiber agglomeration in NR/HDPE blends. The optical microscope analysis shows MK fibers is shorter than original fiber lengths after NaOH-LENR surface modification. The internal bonding forces of MK fiber seems to be weaker than external force exerted on it, therefore, the MK fiber has broken to smaller particles and reduced the mechanical properties of NR/HDPE/MK(20%) bio-composite.

Medición comparativa de la densidad urinaria: tira reactiva, refractómetro y densímetro

OpenAIRE

Costa, Christian Elías; Bettendorff, Carolina; Bupo, Sol; Ayuso, Sandra; Vallejo, Graciela

2010-01-01

Introducción. La densidad urinaria se utiliza en la clínica para evaluar la capacidad renal de concentrar y diluir la orina. Se puede medir mediante tres métodos: urodensímetro (UD), refractómetro (RE) y tiras reactivas (TR). Objetivo. Evaluar la exactitud de diferentes métodos de medición de la densidad urinaria. Diseño del estudio. Transversal, comparativo, con recolección prospectiva de datos. Material y métodos. Se analizaron 156 muestras de orina de pacientes pediátricos, durante abril y...

O papel do professor junto ao aluno com Altas Habilidades

Directory of Open Access Journals (Sweden)

Andréia Jaqueline Devalle Rech

2012-03-01

Full Text Available .Quando se discute a Educação Especial é comum, num primeiro momento, lembrar do aluno que compõe o especial na Educação como aquele com deficiência mental, auditiva, visual ou física. No entanto, assim como essas crianças, também os alunos com altas habilidades necessitam de um atendimento especializado, pois ele também é um sujeito da Educação Especial. Nesse sentido, este artigo apresenta a definição de altas habilidades, baseada na teoria de um pesquisador norte-americano e, como foco principal algumas questões que envolvem o professor de forma mais direta com o aluno com altas habilidades em sala de aula. Entre elas estão: questões sobre a aprendizagem escolar desses alunos, bem como os fatores que fazem parte desse processo, estratégias de ensino e a importância da identificação dos alunos com altas habilidades.Palavras-chave: Educação Especial. Professor. Aluno com Altas Habilidades

Elevada densidade de semeadura aumenta a produtividade da soja? Respostas da radiação fotossinteticamente ativa

Directory of Open Access Journals (Sweden)

Fabiano André Petter

2016-01-01

Full Text Available Resumo Estudos recentes têm abordado o uso da prática da elevada densidade de semeadura na cultura da soja. Entretanto, os resultados práticos dessa técnica são divergentes. Assim, pesquisas nesse campo são importantes para elucidar os efeitos diretos dessa prática de manejo, como, por exemplo, a interferência no uso da radiação fotossinteticamente ativa (RFA. Portanto, objetivou-se com este estudo avaliar a dinâmica da RFA em diferentes densidades de cultivo na cultura da soja. Para tanto, conduziu-se um experimento a campo com delineamento em blocos casualizados com os tratamentos distribuídos em arranjo fatorial 3 × 5: três cultivares de soja RR® (P98Y12, TMG 132 e M-Soy 9056 e cinco densidades de semeadura (20, 30, 40, 50 e 60 plantas∙m–2 com quatro repetições. Foram avaliados massa seca da parte aérea, radiação fotossinteticamente ativa no dossel inferior (RFA-I e superior (RFA-S, intercepção da RFA, taxa de crescimento da cultura (TCC, taxa de crescimento relativo (TCR, taxa de assimilação líquida (TAL, eficiência de uso da radiação (EUR, coeficiente de extinção luminosa (k, índice de colheita de grãos (ICG, peso de 1.000 grãos e produtividade. Independentemente do cultivar, as densidades de 20 e 30 plantas∙m–2 proporcionaram os maiores valores de TAL, TCR, k, ICG e produtividade. Apenas o uso dos parâmetros EUR, TCC e RFA interceptada não fornece informações sólidas para predizer a eficiência do cultivo adensado na cultura da soja. As densidades de cultivo tradicionalmente utilizadas se sobrepõem às demais quanto à qualidade da RFA no dossel e produtividade da soja.

Environmental and economic analysis of end of life management options for an HDPE product using a life cycle thinking approach.

Science.gov (United States)

Simões, Carla L; Pinto, Lígia M Costa; Bernardo, C A

2014-05-01

Manufacturers have been increasingly considering the implication of materials used in commercial products and the management of such products at the end of their useful lives (as waste or as post-consumer secondary materials). The present work describes the application of the life cycle thinking approach to a plastic product, specifically an anti-glare lamellae (used for road safety applications) made with high-density polyethylene (HDPE). This study shows that optimal environmental and economic outcomes associated with this product can be realized by recovering the material at the end of its useful life (end of life, EoL) and by using the recycled HDPE as a raw material in the production of new similar products. The study confirmed the applicability of the life cycle thinking approach by industry in sustainable products development, supporting the development of robust environmental and economic guidelines.

TransAlta 2003 annual report

International Nuclear Information System (INIS)

2004-01-01

This annual report presents financial information from TransAlta Corp., along with a review of its operations throughout 2003 and a summary of the how the electric utility has performed in terms of power generation, independent power producers, transmission and energy marketing. TransAlta is one of the largest non-regulated power generation and wholesale marketing companies in Canada. It's assets include coal-fired, gas-fired, hydro and renewable generation facilities in Canada, the United States, Mexico and Australia. Reported earnings in 2003 were $1.26 per share compared to $1.17 in 2002. The strong first quarter was followed by harsh market conditions, low water levels which affected hydro production, and pricing restrictions in Ontario that reduced contribution from the Sarnia plant. This report outlines the utility's progress in increasing revenue and producing more power. In 2003, unplanned outages were reduced by 7 per cent and injury frequency rate was reduced by 27 per cent. The installation of 114 wind turbines in Fort Macleod, Alberta, increased TransAlta's renewable energy capacity to 3.7 per cent in 2003. The wind farm produces 75 MW of electricity, enough to power more than 32,500 homes annually. This report summarized the company's energy resource activities and presented an operations review as well as consolidated financial statements and common share information. This included the utility's assets, liabilities, revenues, expenses and cash flows. Revenue and expenditure statements were summarized by source. refs., tabs., figs

Dendrogramas de densidade para Hovenia dulcis Thunberg na região central do estado do Rio Grande do Sul, Brasil

Directory of Open Access Journals (Sweden)

Gerson Luiz Selle

2010-09-01

Full Text Available O objetivo principal deste trabalho foi elaborar dendrogramas para o manejo de densidade (DMD, em populações de Hovenia dulcis localizadas na região central do estado do Rio Grande do Sul, Brasil. Para tanto, foram utilizadas informações de dois povoamentos, com idades de 25 anos, localizado na Fundação de Pesquisa Agropecuária (FEPAGRO e de uma população de árvores livres, com DAPs variando de 5 a 45 cm, localizado no campus da Universidade Federal de Santa Maria (UFSM, RS. Nos povoamentos sob concorrência, os dados foram coletados em árvores dos estratos dominante, intermediário e dominado, pelo método da densidade pontual. As árvores livres de concorrência foram coletadas sob a forma de censo. Como conclusão obteve-se que o modelo de Reineke ajustou-se satisfatoriamente para estimar as linhas de densidade de fechamento do dossel e de autodesbaste, com os coeficientes angulares se aproximando de -1,5, comprovando que a lei da potência de -3/2 de autodesbaste foi contemplada e que a hipótese postulada por Reineke tambem foi satisfeita. A densidade populacional, para a lotação do dossel, foi de 42,5% do número máximo de árvores, sendo possível construir diagramas para o manejo da densidade, dos 5 aos 31 cm de diâmetro da árvore de área basal média.

Effect of gamma irradiation on mechanical, thermal and rheological behavior of HDPE filled with seaweed residues

International Nuclear Information System (INIS)

Catano, L.; Albano, C.; Karam, A.; Dominguez, N.; Sanchez, Y.; Gonzalez, J.

2005-01-01

The present work shows the results obtained during the investigation of the influence of gamma irradiation on mechanical, thermal and rheological properties of high-density polyethylene (HDPE) filled with seaweed residues (SR). The SR used was located on Venezuelan coastlines and they are composed mainly by CaCO 3 in aragonite phase. The HDPE was extruded along with the filler at different compositions (20, 30 and 40 wt.%). The composites were exposed to a 60 Co source irradiated at 25 and 100 kGy. From the obtained results, it was noticed that Young modulus remained constant with filler content. Moreover, the influence of filler content was found to be more prominent on properties like tensile stress and elongation at break. On the other hand, thermal analysis showed that filler content had no significant influence on thermal stability. Still, it is necessary to point out that low radiation doses improved thermal stability of the composites. From rheological studies it was observed a decreasing of melt flow index (MFI) by increasing the SR amount and radiation. Therefore, was determinate that high filler content composites are the best choice to be considered for biomedical and industrial applications

Embarcaciones de alta velocidad

OpenAIRE

Rodrigo de Larrucea, Jaime

2008-01-01

revolución tecnológica, con el desarrollo de nuevos tipos de buques de diseños cada vez más específicos y adaptados a su navegación y función. Sin duda una de las más espectaculares innovaciones es la de los buques de alta velocidad.

Avaliação dos efeitos da adição de sal e da densidade no transporte de tambaqui

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Gomes Levy de Carvalho

2003-01-01

Full Text Available Os objetivos deste trabalho foram testar a eficiência do sal como redutor de estresse e verificar a melhor densidade de transporte de juvenis de tambaqui (Colossoma macropomun em caixas de plástico adaptadas. No primeiro experimento foram testadas diferentes concentrações de sal de cozinha (NaCl na água; no segundo, o transporte foi realizado por três horas em caixas de plástico de 200 L estocadas com diferentes densidades de peixe, com 8 g de sal/L de água. O cortisol plasmático dos peixes sofreu aumento significativo após o transporte no tratamento sem sal e com 2 g de sal/L de água, retornando para níveis normais após 96 horas. A glicose plasmática dos peixes sofreu aumento após o transporte em todas as concentrações de sal testadas, com exceção da com 8 g/L de água, retornando para níveis normais em 24 horas. Nos peixes transportados no segundo experimento, com 8 g de sal/L de água, não foi verificada mudança significativa no cortisol plasmático, mas a glicose aumentou significativamente em todas as densidades após o transporte, retornando para níveis normais em 24 horas. Houve mortalidade de 11% em uma das repetições da densidade de 200 kg/m³ de água. Para o transporte com 8 g de sal/L de água, a densidade máxima deve ser de 150 kg/m³ de água. Nesta densidade os parâmetros físico-químicos de qualidade de água se mantêm com características adequadas, as respostas ao estresse são mínimas e não há mortalidade.

Technical Letter Report - Preliminary Assessment of NDE Methods on Inspection of HDPE Butt Fusion Piping Joints for Lack of Fusion

International Nuclear Information System (INIS)

Crawford, Susan L.; Cumblidge, Stephen E.; Doctor, Steven R.; Hall, Thomas E.; Anderson, Michael T.

2008-01-01

The U.S. Nuclear Regulatory Commission (NRC) has a multi-year program at the Pacific Northwest National Laboratory (PNNL) to provide engineering studies and assessments of issues related to the use of nondestructive evaluation (NDE) methods for the reliable inspection of nuclear power plant components. As part of this program, there is a subtask 2D that was set up to address an assessment of issues related to the NDE of high density polyethylene (HDPE) butt fusion joints. This work is being driven by the nuclear industry wanting to employ HDPE materials in nuclear power plant systems. This being a new material for use in nuclear applications, there are a number of issues related to its use and potential problems that may evolve. The industry is pursuing ASME Code Case N-755 entitled 'Use of Polyethylene (PE) Plastic Pipe for Section III, Division 1, Construction and Section XI Repair/Replacement Activities' that contains the requirements for nuclear power plant applications of HDPE. This Code Case requires that inspections be performed after the fusion joint is made by visually examining the bead that is formed and conducting a pressure test of the joint. These tests are only effective in general if gross through-wall flaws exist in the fusion joint. The NRC wants to know whether a volumetric inspection can be conducted on the fusion joint that will reliably detect lack-of-fusion conditions that may be produced during joint fusing. The NRC has requested that the work that PNNL is conducting be provided to assist them in resolving this inspection issue of whether effective volumetric NDE can be conducted to detect lack of fusion (LOF) in the butt HDPE joints. PNNL had 24 HDPE pipe specimens manufactured of 3408 material to contain LOF conditions that could be used to assess the effectiveness of NDE in detecting the LOF. Basic ultrasonic material properties were measured and used to guide the use of phased arrays and time-of-flight diffraction (TOFD) work that was

HDPE (High Density Polyethylene) pipeline and riser design in Guanabara Bay: challenges and solutions

Energy Technology Data Exchange (ETDEWEB)

Bomfimsilva, Carlos; Jorge, Joao Paulo Carrijo; Schmid, Dominique; Gomes, Rodrigo Klim [INTECSEA, Sao Paulo, SP (Brazil); Lima, Alexander Piraja [GDK, Salvador, BA (Brazil)

2009-12-19

Worldwide shipments of plastic pipes are forecasted to increase 5.2% per year since 2008, being commonly used for water supply and sewage disposal. The HDPE (High Density Polyethylene) pipes have been applied recently to deliver potable water and fire fighting water for the main pier of the LNG system in Guanabara Bay, Rio de Janeiro. The system contains three sizes of pipe outside diameter, 110 mm and 160 mm for water supply, and 500 mm for the fire fighting system. The main design challenges of the pipeline system included providing on-bottom stability, a suitable installation procedure and a proper riser design. The on-bottom stability calculations, which are quite different from the conventional steel pipelines, were developed by designing concrete blocks to be assembled on the pipeline in a required spacing to assure long term stability, knowing that plastic pipes are buoyant even in flooded conditions. The installation procedure was developed considering the lay down methodology based on surface towing technique. The riser was designed to be installed together with additional steel support structure to allow the entire underwater system to have the same plastic pipe specification up to the surface. This paper presents the main challenges that were faced during the design of the HDPE pipelines for the LNG system in Guanabara Bay, addressing the solutions and recommendations adopted for the plastic underwater pipeline system.

Bienestar psicológico en personas con alta capacidad intelectual

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Pedro Ramiro Olivier

2016-12-01

Full Text Available El bienestar psicológico en las personas de alta capacidad intelectual ha sido motivo de controversia en la literatura especializada. En ocasiones se ha considerado que estas personas son más proclives a un desajuste psicológico, mientras que otras veces los resultados han sido poco concluyentes. En el presente trabajo se ha estudiado el bienestar psicológico en personas de altas capacidades intelectuales, administrando la Escala de Bienestar Psicológico a 28 participantes de edades comprendidas entre los 22 y 34 años de edad. Fueron divididos en 2 grupos, uno de altas capacidades y otro de inteligencia estándar. El grupo de altas capacidades había sido identificado como tal 25 años atrás, cuando tenían una edad comprendida entre los 5 y 13 años, utilizando el modelo de los 3 anillos de Renzulli. Los resultados indicaron la inexistencia de diferencias significativas entre los participantes de altas capacidades e inteligencia estándar en las diferentes subescalas de bienestar personal, a excepción de la subescala de bienestar material.

Niche conservatism of Eulophia alta, a trans-Atlantic orchid species

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Marta Kolanowska

2014-03-01

Full Text Available The genus Eulophia embraces over 230 species distributed through the tropical and subtropical Africa, Asia, Australia and the Americas. In Neotropics it is represented by a sole species – E. alta. The aim of the presented study was to evaluate the difference between ecological niches occupied by American and African populations of this species based on the ecological niche modeling. The similarity between the glacial and present niches occupied by E. alta was calculated and the factors limiting the species occurrence were identified. Areas of seasonal tropical forest, tropical savanna and woodland served as refugia for the studied species during last glacial maximum and they were more widespread in Neotropics than in Africa. No significant niche shift after last glacial maximum was observed. The distribution of E. alta in its whole range is restricted mainly by temperature seasonality. The differences in the niches occupied by African and Neotropical populations of E. alta suggest preglacial disjunction of the species range and independent adaptation of both groups. Despite the significant range disjunction of E. alta the species is characterized by relatively high degree of niche conservatism.

Aclimatação de mudas de acariquara à alta irradiância Acclimation of manwood seedlings to full sunlight

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Nilvanda dos Santos Magalhães

2009-07-01

Full Text Available O objetivo deste trabalho foi determinar as mudanças fisiológicas que ocorrem em acariquara (Minquartia guianensis durante o processo de aclimatação à alta irradiância, bem como a estratégia de aclimatação dessa espécie. Plantas mantidas em baixa irradiância foram transferidas para alta irradiância por 290 dias. Durante esse período, foi medida a relação entre fluorescência variável e máxima (Fv/Fm, em folhas desenvolvidas à sombra e, após a senescência prematura por foto-oxidação, em folhas aclimatadas ao sol. Ao final do experimento, foram determinadas as características fotossintéticas e anatômicas da folha. A exposição à alta irradiância causou, logo após a transferência, forte fotoinibição e foto-oxidação parcial da folhagem, mas não provocou a morte da planta. Folhas produzidas no ambiente ensolarado apresentaram valores de Fv/Fm similares aos do controle. A fotossíntese saturada por luz e a fotossíntese saturada por CO2 foram 90 e 50% maiores em plantas aclimatadas à alta irradiância. A velocidade máxima de carboxilação da rubisco e a taxa máxima de regeneração da ribulose bisfosfato seguiram a mesma tendência. Folhas produzidas ao sol apresentaram maior densidade estomática e maior espessura foliar. A produção de folhas novas é a principal estratégia de aclimatação da acariquara à alta irradiância.The aim of this work was to determine the physiological changes that occur in manwood (Minquartia guianensis during the acclimation process to high irradiance, and also to determine the acclimation strategy of this species. Plants kept in low light were transferred to high irradiance for 290 days. During this period the ratio between variable fluorescence and maximum fluorescence (Fv/Fm was measured in leaves developed in the shade, and after premature senescence due to photooxidation, in sun-acclimated leaves. At the end of the experimental period the anatomic and photosynthetic

HDPE/HA composites obtained in solution: Effect of the gamma radiation

International Nuclear Information System (INIS)

Carmen, Albano; Arquimedes, Karam; Rosestela, Perera; Gema, Gonzalez; Nohemy, Dominguez; Jeanette, Gonzalez; Yanixia, Sanchez

2006-01-01

Radiation is employed to sterilize composite materials used in the biomedical field. Due to the changes induced by radiation onto polymeric materials, it is important to study variations in their melt flow index (MFI), as well as in their mechanical and thermal properties. In this work, those previous parameters were determined in composites obtained via solution of a high-density polyethylene (HDPE) in decalin, with different amounts of hydroxyapatite (HA), varying from 10 to 30 parts per hundred, after being exposed to gamma radiation at absorbed doses between 25 and 100 kGy. After the irradiation, the MFI of HDPE dissolved in decalin and precipitated afterwards and without filler increased from 6 to 24 g/10 min at the highest absorbed doses. This behavior was also observed in composites with 10 pph of HA, being the increase less pronounced, specifically in the range between 50 and 100 kGy. Composites with 20 and 30 pph of HA showed a maximum MFI value at 50 kGy, which decreased at higher doses. This implies that the filler begin to exert an influence because it does not melt at the test temperature and consequently, it does not flow. It was observed that Young's modulus increased with HA addition due to rigidity of the ceramic filler. Radiation did not significantly affect this tensile property. On the other hand, the tensile strength did not show significant variations at the different doses but the filler content did affect this property improving it. Finally, elongation at break showed a drastic decrease with filler addition. When the thermal behavior was studied it was noticed that crystallization and melting temperatures remained unchanged. Instead, crystallinity degree slightly increased in the composites, and a little decrease was obtained when they were irradiated

La materia en condiciones extremas de densidad y temperatura

OpenAIRE

Morones Ibarra, José Rubén

2013-01-01

El estudio de las propiedades de la materia cuando se encuentra sometida a condiciones extremas de temperatura y presión ha llamado la atención de los físicos nucleares y de partículas elementales debido a la importancia que este tema tiene para conocer las condiciones iniciales del universo. En los primeros instantes del Gran Estallido (Big Bang) el universo era una región muy pequeña del espacio y por lo tanto su densidad y temperatura eran enormes. Para ente...

Estabilidad de procesamiento de polímeros: índice de degradación en proceso

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Andrés Felipe Rojas González

2015-06-01

Full Text Available Se presentan los resultados del análisis de estabilidad en proceso para polietileno de alta densidad grado extrusión (PEAD-GE, polietileno de alta densidad grado inyección (PEAD-GI, polietileno de baja densidad (PEBD, poliácido láctico (PLA, policarbonato (PC, poliestireno (PS, polimetíl metacrilato (PMMA y polipropileno (PP. Estos polímeros se reprocesaron en 5 ciclos de extrusión, inyección y extrusión/inyección. Cada polímero virgen y reprocesado se caracterizó respecto al índice de fluidez y se calculó su estabilidad en proceso mediante el índice de degradación en proceso (IDP. Se encontró que la estabilidad de los polímeros, de mayor a menor, durante la extrusión es: PEBD> PS> PMMA> PEAD-GI> PP> PLA, y en la inyección: PEAD-GI> PP> PLA >PC. Además, se determinó que la velocidad de giro del husillo no afecta la degradación en proceso.

Densidade e diversidade fenotípica de bactérias diazotróficas não simbióticas em solos da Reserva Biológica Serra dos Toledos, Itajubá (MG

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Talita Filomena Silva

2011-04-01

Full Text Available Bactérias diazotróficas não simbióticas (BDNS atuam no desenvolvimento das plantas por meio da fixação biológica de nitrogênio e também pela produção e liberação de substâncias reguladoras do crescimento vegetal. Este estudo objetivou avaliar a densidade e diversidade fenotípica desse grupo de bactérias em fragmentos de solo da Reserva Biológica Serra dos Toledos e entorno, em Itajubá/MG. Essa reserva localiza-se na Área de Proteção Ambiental da Mantiqueira, constituindo-se em uma importante área de recarga e de abrigo à flora e fauna endêmicas. Amostras de solo superficial foram coletadas em áreas com diferentes declividades na reserva, em épocas representativas das estações de inverno (setembro/2006 e verão (abril/2007. A densidade, avaliada pelo número mais provável, utilizando os meios de cultura NFb, JNFb e Fam, para Azospirillum spp., Herbaspirillum spp. e A. amazonense, respectivamente, variou de 0,12 a 75,60 (NMP x 10(5 bactérias g-1 solo seco. Foram obtidos 172 e 174 isolados, respectivamente para as amostras de inverno e verão, dos quais 30 e 55 % apresentaram similaridade igual ou superior a 70 % com as estirpes-tipo Azospirillum brasilense, A. amazonense, A. lipoferum, Herbaspirillum seropedicae e Burkholderia brasilensis. O resultado do comportamento dos isolados com base na tolerância à salinidade nem sempre foi semelhante ao obtido pelas características fenotípicas culturais a 70 % de similaridade, sendo indicado para estudos complementares de diversidade desses organismos. As BDNS apresentam potencial de utilização em estudos de avaliação da qualidade e sustentabilidade de ecossistemas. No entanto, apesar da alta densidade e diversidade fenotípica em solos da reserva, maiores valores foram obtidos no entorno, evidenciando o efeito positivo da cobertura vegetal do tipo gramíneas sobre elas, independentemente da variação climática.

Influencias de la densidad y podas sobre la producción de Pinus taeda L. a los 7 años de edad.

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Rubén Costas

2010-08-01

Full Text Available En un ensayo con 3 niveles de densidad y 12 tratamientos de poda, se evaluaron los efectos de la densidad, la altura de poda, el número de levantes de poda y la interacción entre la densidad y las podas sobre la producción de la masa de Pinus taeda L. a los 7 años de edad. Las variables evaluadas fueron el diámetro a la altura de pecho medio (DAP, la altura media, el volumen individual, el volumen por unidad de superficie, el área basal, el diámetro máximo sobre muñón (DMSM, el coeficiente de forma de Girard (CFG, el diámetro de ramas (DRBC y el ángulo de inserción de las ramas (ARBC en la base de la copa. En los tratamientos con mayor densidad de plantación se observaron mayores volúmenes por unidad de superficie, área basal y CFG que en los tratamientos con menor densidad. Estos produjeron mayores DAP, volúmenes individuales, DMSM, DRBC y ARBC que los tratamientos con mayores densidades. Los tratamientos con menores alturas finales de poda produjeron mayores DAP, volúmenes individuales, área basal y volúmenes por unidad de superficie que los tratamientos con mayores alturas de poda. Los menores DMSM se obtuvieron con alturas finales de poda de 3,30 m y 4,40 m realizadas a los 4 años de edad y los mayores DMSM ocurrieron al no efectuarse podas a los 5 años hasta 5,50 m y 6,60 m. No se encontraron diferencias significativas entre los valores medios de DRBC, ARBC y CFG producidos por los 12 tratamientos de poda. La interacción entre densidad y los tratamientos de poda no fue significativa para ninguna de las variables respuestas.

Cócs. Hallmark of the Terra Alta

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Maria Del Loreto Meix

2004-04-01

Full Text Available This article looks at the traditional cake making in the Terra Alta (Catalonien area linked to festivities, and in particular the pastries usually made. In this area the pastries are known as cócs, a word common to Terra Alta and the neighbouring districts of Ribera d'Ebre and the Priorat. Locally produced mistelle, sweet or rancid wine is served with the pastries. Nowadays, the bakeries and cake makers in the area's towns and villages also produce traditionally crafted products, that used only to be homemade.The article, resulting from the final degree project produced by the author for her Humanities degree at the UOC, offers a privileged look at the richness of the Terra Alta in terms of its gastronomic history, customs and its high regard for its cakes. The author, who has previous experience in the field, places the specific aspects of Terra Alta cake making in the context of the Mediterranean cultures with common roots dating back to the ancient and medieval worlds and which still have an easily identifiable "family feel", whilst looking, from an ethnographic point of view, at what she calls the "world of wheat" in the area, (the dough for bread, the craft of the baker, the ovens and other tools, and the associated traditions, among other things. In short, she rescues a living part of the local day-to-day activities and places it under the microscope of food history, whilst providing information that may well be of interest for study from other points of view.

Investigación en materiales sometidos a altas presiones

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Juan Carlos Fallas

2010-10-01

Full Text Available El estudio de materiales sometidos a altas presiones es un tema de profundo interés en el campo científico e ingenieril actual. Diferentes análisis experimentales permiten descubrir los efectos que esta condición genera en la estructura molecular de un determinado compuesto.La implementación de la celda de diamante para altas presiones ha revolucionado este tema en las últimas décadas, al ser una herramienta vital en el desarrollo de estas pruebas. Presiones superiores, inclusive a los 20 Gpa, pueden ser generadas con este artefacto.Adicionalmente, la posibilidad de caracterizar muestras bajo estos parámetros y la inclusión de otras variables, como altas temperaturas, ofrecen un ambiente propicio para la evaluación de materiales bajo condiciones extremas.Este artículo explica los fundamentos básicos de la ciencia de materiales a altas presiones. Aspectos relevantes acerca de la celda de diamante y de la ejecución de experimentos son tratados en diferentes apartados. Se quiere compartir los alcances que esta disciplina posee, así como diferentes resultados que se han logrado en varias aplicaciones.Investigaciones en materiales para el almacenamiento de hidrógeno y energía, así como la simulación de condiciones presentes a muy altas profundidades en la Tierra, son casos que se tomaron en cuenta para ejemplificar áreas donde existen aplicaciones sustanciales.

Prácticas de Física: Medición de masas. Determinación de densidades con la balanza hidrostática

OpenAIRE

Beléndez, Augusto; Bernabeu, Guillermo; Vera Guarinos, Jenaro; Pastor Antón, Carlos; Martín García, Agapito

1988-01-01

El objetivo de esta práctica es conocer los distintos métodos de pesada y el empleo del método de la tara constante para determinar la densidad de líquidos y sólidos con la balanza hidrostática, utilizando un líquido patrón. Se trata de obtener la densidad de un líquido utilizando un picnómetro y un líquido de referencia (agua destilada). Se determinará primero la masa del picnómetro lleno de agua destilada y después lleno con el líquido problema. Se obtendrá la densidad relativa del líquido ...

Synthesis of carbon nanostructures from high density polyethylene (HDPE) and polyethylene terephthalate (PET) waste by chemical vapour deposition

Science.gov (United States)

Hatta, M. N. M.; Hashim, M. S.; Hussin, R.; Aida, S.; Kamdi, Z.; Ainuddin, AR; Yunos, MZ

2017-10-01

In this study, carbon nanostructures were synthesized from High Density Polyethylene (HDPE) and Polyethylene terephthalate (PET) waste by single-stage chemical vapour deposition (CVD) method. In CVD, iron was used as catalyst and pyrolitic of carbon source was conducted at temperature 700, 800 and 900°C for 30 minutes. Argon gas was used as carrier gas with flow at 90 sccm. The synthesized carbon nanostructures were characterized by FESEM, EDS and calculation of carbon yield (%). FESEM micrograph shows that the carbon nanostructures were only grown as nanofilament when synthesized from PET waste. The synthesization of carbon nanostructure at 700°C was produced smooth and the smallest diameter nanofilament compared to others. The carbon yield of synthesized carbon nanostructures from PET was lower from HDPE. Furthermore, the carbon yield is recorded to increase with increasing of reaction temperature for all samples. Elemental study by EDS analysis were carried out and the formation of carbon nanostructures was confirmed after CVD process. Utilization of polymer waste to produce carbon nanostructures is beneficial to ensure that the carbon nanotechnology will be sustained in future.

Determination of water vapor transmission rate (WVTR) of HDPE bottles for pharmaceutical products.

Science.gov (United States)

Chen, Yisheng; Li, Yanxia

2008-06-24

The objective of this study was to investigate the effects of experimental conditions for measuring the water vapor transmission rate (WVTR) of high-density polyethylene (HDPE) bottles using a steady-state sorption method. Bottles were filled with desiccant, closed with caps and heat induction sealed, and then stored in stability chambers at controlled temperature and relative humidity. Weight gain of the bottles was determined every 1 or 2 weeks until a linear weight gain profile was obtained. WVTR of the bottles was determined from the slope of the linear portion of the weight gain versus time profile. The effects of desiccants and temperature/humidity were studied. Results show that, with a sufficient amount of anhydrous calcium chloride in bottles, a negligibly low and sufficiently constant headspace humidity is maintained, and a steady-state permeation rate is achieved. For all 8 sizes of bottles used in this study, steady-state was achieved in 1 or 2 weeks after the experiment was started. This method provided reproducible WVTR data for HDPE bottles. Apparent moisture permeability of all 8 sizes of bottles was (2.3+/-0.3)x10(-7), (2.6+/-0.2)x10(-7), and (3.4+/-0.2)x10(-7)cm(2)/s at 25 degrees C, 30 degrees C, 40 degrees C, respectively. Moisture permeability determined from the current study was similar to data reported in the literature, indicating that the steady-state weight gain method can be used to obtain reliable WVTR of containers for pharmaceutical products.

Substitution potentials of recycled HDPE and wood particles from post-consumer packaging waste in Wood-Plastic Composites.

Science.gov (United States)

Sommerhuber, Philipp F; Welling, Johannes; Krause, Andreas

2015-12-01

The market share of Wood-Plastic Composites (WPC) is small but expected to grow sharply in Europe. This raises some concerns about suitable wood particles needed in the wood-based panels industry in Europe. Concerns are stimulated by the competition between the promotion of wooden products through the European Bioeconomy Strategy and wood as an energy carrier through the Renewable Energy Directive. Cascade use of resources and valorisation of waste are potential strategies to overcome resource scarcity. Under experimental design conditions, WPC made from post-consumer recycled wood and plastic (HDPE) were compared to WPC made from virgin resources. Wood content in the polymer matrix was raised in two steps from 0% to 30% and 60%. Mechanical and physical properties and colour differences were characterized. The feasibility of using cascaded resources for WPC is discussed. Results indicate the technical and economic feasibility of using recycled HDPE from packaging waste for WPC. Based on technical properties, 30% recycled wood content for WPC is feasible, but economic and political barriers of efficient cascading of biomass need to be overcome. Copyright © 2015 Elsevier Ltd. All rights reserved.

Evaluación de densidades de siembra en tomate (Lycopersicon esculentum Mill en invernadero

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Jos\\u00E9 Cruz Carrillo

2003-01-01

Full Text Available Esta investigación se realizó de junio a diciembre del 2001 en el módulo de horticultura protegida del Instituto Tecnológico Agropecuario de Oaxaca No. 23 ubicado en la ex Hacienda de Nazareno, Xoxocotlan, Oax., con el propósito de evaluar el efecto de tres densidades de plantación en el desarrollo vegetativo y producci ón de diferentes híbridos de tomate con crecimiento indeterminado cultivados bajo invernadero. Los híbridos de tomate fueron el SXT, DRW3410 y SXT0289. No hubo diferencia estad ística para los híbridos, sólo para densidades de plantación, obteniendo los mejores rendimientos 5,3 plantas/m2 y 4 plantas/ m2 con 17,52 y 17,37 kg/m2, respectivamente, lo que represent ó en promedio un rendimiento de 151,6 t/ha.

Resolução lamelar num novo microscópio eletrônico de varredura Lamellar resolution in a new scanning electron microscope

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Hans-Jürgen Kestenbach

1997-03-01

Full Text Available RESUMO: Trabalhando com elétrons de baixa energia (na faixa de 1keV, o novo microscópio eletrônico de varredura dispensa a etapa de metalização e permite a observação direta da estrutura lamelar de polímeros semicristalinos, sem a necessidade de preparação de amostras. São apresentados exemplos da morfologia lamelar do PVDF em função das condições de processamento e da temperatura de cristalização, em filmes contendo as fases a, b e g. Um outro exemplo revela o crescimento inicial da camada transcristalina que se formou ao longo de uma fibra de polietileno de ultra-alto peso molecular embutida em matriz de polietileno de alta densidade.ABSTRACT: Working with low energy electrons (in the range of 1keV, the new scanning electron microscope permits the lamellar (supermolecular structure of semicrystalline polymers to be observed directly without the need of specimen coating or of any other sample preparation technique. Microscope performance is demonstrated by several examples of high resolution micrographs which show spherulitic, lamellar and fibrilar morphologies developed by the a, b and g phases of PVDF as a function of processing conditions and crystallization temperature. Another example reveals the early stages of transcrystalline layer formation in HDPE reinforced by UHMWPE fibers.

Investigation on the hot melting temperature field simulation of HDPE water supply pipeline in gymnasium pool

Science.gov (United States)

Cai, Zhiqiang; Dai, Hongbin; Fu, Xibin

2018-06-01

In view of the special needs of the water supply and drainage system of swimming pool in gymnasium, the correlation of high density polyethylene (HDPE) pipe and the temperature field distribution during welding was investigated. It showed that the temperature field distribution has significant influence on the quality of welding. Moreover, the mechanical properties of the welded joint were analyzed by the bending test of the weld joint, and the micro-structure of the welded joint was evaluated by scanning electron microscope (SEM). The one-dimensional unsteady heat transfer model of polyethylene pipe welding joints was established by MARC. The temperature field distribution during welding process was simulated, and the temperature field changes during welding were also detected and compared by the thermo-couple temperature automatic acquisition system. Results indicated that the temperature of the end surface of the pipe does not reach the maximum value, when it is at the end of welding heating. Instead, it reaches the maximum value at 300 sand latent heat occurs during the welding process. It concludes that the weld quality is the highest when the welding pressure is 0.2 MPa, and the heating temperature of HDPE heat fusion welding is in the range of 210 °C-230 °C.

An investigation on morphology and mechanical properties of HDPE/nanoclay/nanoCaCO_3 ternary nanocomposites

International Nuclear Information System (INIS)

Garmabi, Hamid; Tabari, Seyed Emad Alavi; Javadi, Azizeh; Behrouzi, Hormoz; Hosseini, Gholamabbas

2016-01-01

Ternary Nanocomposites of high-density polyethylene (HDPE) containing two types of nano particles, a layered organoclay (Closite 15A) and a spherical nano Calcium Carbonate (CaCO_3), with various compositions were prepared using melt mixing. Maleic anhydride grafted polyethylene (MA-g-PE) was used to enhance the dispersion of nanofillers and better interface adhesion. Three different levels of nanoclay (1, 3, 5 wt. %), CaCO_3 (6, 8, 10 wt. %) and MA-g-PE (3, 6, 9 wt. %) were used. The mixing was done in two steps: First a concentrated masterbatch of nanoparticles in HPDE and MA-g-PE was prepared using an internal mixer and then melt-mixing of nanocomposites was done in a lab scale co-rotating twin screw extruder. The morphology of samples was studied using Scanning Electron Microscopy (SEM) and mechanical properties were evaluated using tensile and impact tests. According to the SEM micrographs, nanofillers were well dispersed in the HDPE matrix and XRD patterns showed the intercalation of nanoclay layers too. Generally using the layered nanoclay can enhance the tensile modulus while the use of spherical nano CaCO_3 results into improved toughness. It was found that co-incorporation of these two types of nanofillers, leads to improve the stiffness and minimize the reduction of impact strength, simultaneously.

Diversidade de formigas (Hymenoptera: Formicidae) em sistemas de cultivo de algodoeiro no Distrito Federal

OpenAIRE

Monteiro, André Fábio Medeiros

2009-01-01

Diversos estudos mostram que as formigas exercem papéis importantes para o funcionamento dos agroecossistemas. Néctar extrafloral, exsudados de pulgões e alta densidade de herbívoros atraem formigas predadoras para o algodoeiro, que poderiam protegê-lo de danos por pragas. Isso dependeria de circunstâncias regionais, da intensidade de manejo de sistemas de cultivo específicos e da densidade e agressividade de formigas dominantes. Os objetivos gerais desse estudo foram avaliar o...

Intervalo hídrico ótimo e densidade crítica de um Latossolo Amarelo coeso sob diferentes usos no ecossistema Tabuleiro Costeiro

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Camila Brasil Dias

Full Text Available RESUMO Os impactos do uso e do manejo na qualidade física do solo têm sido quantificados, utilizando-se o intervalo hídrico ótimo e a densidade crítica do solo. O objetivo deste trabalho foi determinar o intervalo hídrico ótimo (IHO e a densidade crítica de um Latossolo Amarelo coeso, dos Tabuleiros Costeiros do Recôncavo da Bahia, submetido a diferentes usos e manejo do solo. Foram selecionadas três áreas, sobre solo coeso típico, submetidas aos seguintes usos e manejos: mata nativa (Mata Atlântica; pastagem de Brachiaria decumbens Stapf, em estado de degradação, e cana-de-açúcar, com subsolagem no sulco de plantio. Foram retiradas em cada área 40 amostras com estrutura indeformada, na porção central de cada horizonte (A e AB. Foram determinados nessas amostras, após serem submetidas a dez valores de tensão e pressão, a umidade, a resistência à penetração e a densidade do solo. Na área cultivada com cana, a coleta das amostras foi feita nas linhas de plantio, onde foi realizada a subsolagem. O intervalo hídrico ótimo do horizonte A, da mata, e do Ap, da cana-de-açúcar foram semelhantes e, ambos, maiores que na pastagem. Já no horizonte AB, o IHO da cana-de-açúcar foi maior que o da mata e, o desta, maior que o da pastagem. Os horizontes A e Ap apresentaram valores de densidade crítica maiores que os de AB para todos os usos avaliados. O uso que apresentou maior frequência de valores de densidade do solo acima da densidade crítica foi a pastagem.

Assessment of nanoscopic dynamic mechanical properties and B-C-N triad effect on MWCNT/h-BNNP nanofillers reinforced HDPE hybrid composite using oscillatory nanoindentation: An insight into medical applications.

Science.gov (United States)

Badgayan, Nitesh Dhar; Sahu, Santosh Kumar; Samanta, Sutanu; Rama Sreekanth, P S

2018-04-01

A thrust on improvement of different properties of polymer has taken a contemporary route with advent of nanofillers. Although several nanofillers are existent; MultiWalled Carbon Nanotubes- (MWCNTs) and h-Boron Nitride nanoplatelets-(h-BNNPs) unique combination of 1D and 2D dimensional geometry aids an advantage of B-C-N triad elemental effects on properties of tested samples. The current study aims to investigate the effects of MWCNT and h-BNNP reinforcement in High Density Polyethylene (HDPE) for high load bearing areas of medical applications requiring both elastic and viscous behavior. The results were analyzed keeping a view of its application in areas like HDPE based fracture fixation plates, acetabular cups and others. The composite and hybrid samples with different loadings were prepared after surface modification of nanofillers by mechanical mixing and molding technique. The dynamic nano-mechanical properties like storage modulus, loss modulus and tan delta were assessed for each sample during frequency swept from 10 to 220 Hz. The viscoelastic properties like h c /h m , H/E, elastic-plastic deformation were investigated and evaluated. At a frequency of 10 Hz, the storage and loss modulus of 0.1 CNT increased by 37.56% and decreased by 23.52% respectively on comparison with pure HDPE. This infers a good elastic as well as viscous behavior. Overall elastic behavior of 0.1 CNT was confirmed from tan delta evaluation. The interaction between B-C-N elemental triad had significant effect on creep strength, visco-damping property (h c /h m and H/E), elastic plastic displacement and pile-up and sink-in behavior. Highest creep strength and visco-damping property was exhibited by 0.25 CNT/0.15 BNNP hybrid. The elastic-plastic displacement of hybrid composite was noted as least, which decreased by 30% on comparison with pure HDPE. It can be inferred that presence of 1D-MWCNT and 2D-h-BNNP had significant effect on important dynamic viscoelastic and creep

Avaliação da Densidade dos anestésicos locais e da combinação com adjuvantes: estudo em laboratório Evaluación de la densidad de los anestésicos locales y de la combinación con adyuvantes: estudio en laboratorio Assessment of the densities of local anesthetics and their combination with adjuvants: an experimental study

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Luiz Eduardo Imbelloni

2009-04-01

Full Text Available JUSTIFICATIVA E OBJETIVOS: Uma das mais importantes propriedades físicas que afetam o nível da analgesia obtida após a injeção subaracnoidea de um anestésico local é sua densidade relativa à densidade do líquido cefalorraquidiano (LCR a 37°C. O objetivo deste trabalho foi determinar a densidade das soluções de anestésicos locais com e sem glicose e a combinação de anestésico local com adjuvantes a 20°C, 25°C e 37°C em avaliação laboratorial. MÉTODO: A densidade (g.mL-1 foi medida como auxílio de um densímetro DMA 450, sensível a ± 0,00001 g.mL-1. A densidade e suas variações com a temperatura foram obtidas de todos os anestésicos locais e suas combinações com opioides a 20°C, 25°C e 37°C. A solução é hiperbárica se sua densidade excede a 1,00099, a solução é hipobárica quando a densidade está abaixo de 1,00019 e é isobárica quando a densidade é maior que 1,00019 e menor que 1,00099. RESULTADOS: Ambos, anestésicos locais e adjuvantes, exibem diminuição da densidade quando se aumenta a temperatura. A 37°C, todas as soluções que contêm glicose são hiperbáricas. Na ausência de glicose, todas as soluções são hipobáricas. A 37°C, morfina, fentanil, sufentanil e clonidina são hipobáricas. CONCLUSÕES: A densidade dos anestésicos locais e adjuvantes diminui com o aumento da temperatura e aumenta com a adição de glicose. O conhecimento da baricidade, densidade relativa, ajuda na seleção do anestésico local mais adequado e dos adjuvantes para uso subaracnoideo.JUSTIFICATIVA Y OBJETIVOS: Una de las más importantes propiedades físicas que afectan el nivel de la analgesia obtenida después de la inyección subaracnoidea de un anestésico local, es su densidad relativa a la densidad del líquido cefalorraquídeo (LCR a 37°C. El objetivo de este trabajo fue determinar la densidad de las soluciones de anestésicos locales con y sin glucosa y la combinación de anestésico local con

EFECTO DE LA DENSIDAD DE PLANTACIÓN EN SANDÍA SIN SEMILLA INJERTADA SOBRE BULE (Lagenaria siceraria (Molina Standl.

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Jesus Lopez Elias

2010-11-01

Full Text Available En los últimos años se ha incrementado el interés en sandía injertada sobre portainjertos tolerantes a Fusarium. En virtud de que la densidad de plantación es un factor determinante en el grado de competencia entre las plantas y de que el rendimiento por planta disminuye a medida que la densidad por unidad de superficie se incrementa, el objetivo de este estudio fue evaluar el efecto de tres densidades de plantación, en hileras a 2.0 m de separación con plantas espaciadas a 1.25, 1.55 y 2.00 m, sobre la producción y calidad de sandía sin semilla híbrido ‘Tri-X 313’, injertada sobre bule (Lagenaria siceraria (Molina Standl. híbrido ‘Emphasis’. El experimento se desarrolló utilizando un diseño en bloques completos al azar, con cuatro repeticiones. Las densidades de plantación evaluadas no influyeron sobre la producción de sandía sin semilla, híbrido ‘Tri-X 313’, injertada sobre L. siceraria; Sin embargo, las plantas injertadas mostraron una disminución del rendimiento por superficie con respecto de aquellas sin injertar, que varió del 10 al 24%, por lo que su uso está restingido a suelos con problemas de estrés causado principalmente por enfermedades. El peso promedio del fruto se incrementó en un 10% con el espaciamiento a 2.00 m. Asimismo, el número de frutos por planta disminuyó significativamente a medida que la densidad se incrementó. Los resultados en sandía injertada no fueron positivos por unidad de superficie; sin embargo, se obtuvo mayor producción por planta a menor densidad de plantación (mayor espaciamiento. Dado el incremento en los costos de producción al utilizar plantas injertadas, existe ventaja en el uso de menor densidad de plantación (mayor espaciamiento, pudiendose usar hasta un 50% menos densidad de plantación que en sandía sin injertar, sin afectar significativamente la producción y la

Estudio comparativo de cuatro sistemas de propagación de levadura cervecera por lote alimentado Comparative study of four fed-batch propagation systems of beer yeast

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Hoyos H.

1998-06-01

Full Text Available

Se realizó la propagación por lotes de levadura cervecera y con base en estos resultados se ajustó un modelo matemático. Se llevaron a cabo cuatro fermentaciones con diferentes técnicas de alimentación y se confrontaron los resultados mediante simulación. Las técnicas estudiadas fueron alimentación puntual, alimentación continua-puntual y de alta densidad. La mayor concentración celular y factor de propagación se presentó con el cultivo de alta densidad. La simulación demostró que la alimentación continua o puntual afecta el comportamiento celular, ya sea sobre la velocidad específica y/o el factor estequiométrico Yx/s . Se encontró que la técnica de alta densidad aumenta el factor estequiométrico Yx/s.

Efecto de la administración subcrónica de glucosamina oral en la regulación del peso corporal, glucemia y dislipidemias provocada por una dieta hipercalórica en rata Wistar

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Cornelio Barrientos Alvarado

2014-12-01

Full Text Available Objetivo: Este estudio evaluó el efecto de la glucosamina oral en el sobrepeso y dislipidemia provocada por una dieta hipercalórica en ratas. Métodos: En 4 grupos de ratas Wistar: alimentados con dieta comercial para roedores y agua de beber sin grupo de control y con glucosamina (500 mg/kg-1 por día grupo glucosamina y con dieta hipercalórica enriquecida al 24% (g/g compuesta por manteca de cerdo y agua de beber sin grupo hipercalórico y con glucosamina grupo hipercalórico + grupo glucosamina, durante 22 semanas, se evaluaron el peso corporal, grasa abdominal, niveles de glucemia, triglicéridos, colesterol total y lipoproteínas de alta densidad en suero. Resultados: Se observó un aumento del peso corporal y glucemia en suero con dislipidemias en el grupo con dieta hipercalórica grupo hipercalórico versus grupo de controle (p0.05 y regulándose el peso corporal, las lipoproteínas de alta densidad y la glucemia basal (p<0.05. Conclusion: La glucosamina reguló el peso corporal y la glucemia en sangre y minimizó las dislipidemias provocadas por la dieta hipercalórica, favoreciendo el aumento de colesterol lipoproteínas de alta densidad en las ratas. No afectó el peso corporal y el metabolismo lipídico cuando se administró con dieta comercial.

Sugarcane bagasse ash reinforced HDPE composites: effects of electron-beam radiation crosslinking on tensile and morphological properties

Energy Technology Data Exchange (ETDEWEB)

Teixeira, Jaciele G.; Gomes, Michelle G.; Oliveira, Rene R.; Silva, Valquiria A.; Sartori, Mariana M.; Ortiz, Angel V.; Moura, Esperidiana A.B., E-mail: jacielegteixeira@yahoo.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Sao Paulo, SP (Brazil)

2013-07-01

Environmental issues have led to the development of polymeric materials reinforced with fibers originated from renewable agricultural sources such as pineapple leaf, sisal, jute, piassava, coir, and sugarcane bagasse. Although sugarcane bagasse fiber residues has been extensively studied and used as a source of reinforcement of polymers, the major portion of these residues is currently burnt for energy supply in the sugar and alcohol industries and as a result of its burning, tons of ashes are produced. Due to the inorganic composition, ashes can be used as reinforcement in polymeric materials. This study presents the preparation and characterization of a composite based on HDPE matrix and sugarcane bagasse ashes as reinforcement cross-linked by electron-beam radiation. The HDPE /Ash composite (95:5 wt %) was obtained by using a twin-screw extruder machine followed by injection molding. After extrusion and injection molding process, the composites were subjected to electron-beam radiation, at radiation doses of 150 kGy and 250 kGy using a Dynamitron electron beam accelerator, at room temperature in the presence of air. The irradiated and non-irradiated composite specimens were characterization by tensile and MFI tests, scanning electron microscopy (SEM), X-ray diffraction (XRD) and sol-gel analysis. In addition, ash from bagasse fiber was characterized by WDXRF. (author)

Sugarcane bagasse ash reinforced HDPE composites: effects of electron-beam radiation crosslinking on tensile and morphological properties

International Nuclear Information System (INIS)

Teixeira, Jaciele G.; Gomes, Michelle G.; Oliveira, Rene R.; Silva, Valquiria A.; Sartori, Mariana M.; Ortiz, Angel V.; Moura, Esperidiana A.B.

2013-01-01

Environmental issues have led to the development of polymeric materials reinforced with fibers originated from renewable agricultural sources such as pineapple leaf, sisal, jute, piassava, coir, and sugarcane bagasse. Although sugarcane bagasse fiber residues has been extensively studied and used as a source of reinforcement of polymers, the major portion of these residues is currently burnt for energy supply in the sugar and alcohol industries and as a result of its burning, tons of ashes are produced. Due to the inorganic composition, ashes can be used as reinforcement in polymeric materials. This study presents the preparation and characterization of a composite based on HDPE matrix and sugarcane bagasse ashes as reinforcement cross-linked by electron-beam radiation. The HDPE /Ash composite (95:5 wt %) was obtained by using a twin-screw extruder machine followed by injection molding. After extrusion and injection molding process, the composites were subjected to electron-beam radiation, at radiation doses of 150 kGy and 250 kGy using a Dynamitron electron beam accelerator, at room temperature in the presence of air. The irradiated and non-irradiated composite specimens were characterization by tensile and MFI tests, scanning electron microscopy (SEM), X-ray diffraction (XRD) and sol-gel analysis. In addition, ash from bagasse fiber was characterized by WDXRF. (author)

Variação do incremento anual ao longo do fuste de Pinus taeda L. em diferentes idades e densidades populacionais.

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César Martins Andrade

2010-08-01

Full Text Available A variação do crescimento anual em diferentes alturas do fuste de Pinus taeda L. foi estudada por meio da análise de tronco em árvores do estrato dominante e médio. Foram coletadas secções transversais ao longo do fuste de 9 árvores-amostra, tomadas na base, à altura do peito (DAP, e após, a cada metro. A amostragem foi constituída de 4 árvores provenientes de Canela, Rio Grande do Sul, em floresta com 17 anos de idade, submetida a um desbaste, e 5 árvores de Ponte Alta do Norte, Santa Catarina, em floresta com 34 anos, submetida a cinco desbastes. Os resultados, expressos na forma percentual do incremento em área basal na posição "i", sobre o incremento em área basal ao nível do DAP, mostraram a forte variação na deposição anual de lenho ao longo do fuste em função da densidade populacional, caracterizando os efeitos da competição e da liberação pela execução do desbaste. Árvores sujeitas à competição mostraram maior crescimento nas partes superiores do fuste, enquanto que árvores sob menor concorrência apresentaram maior crescimento em posições inferiores, facilmente identificadas pela forma e inclinação das curvas de incremento.

Basic density and pulp yield relationship with some chemical parameters in eucalyptus trees Densidade e rendimento em polpa celulósica e sua relação com alguns parâmetros químicos no eucalipto

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Ana Maria Loureiro da Seca

2006-12-01

/guaiacilo (S/G e seringaldeído/vanilina (S/V. As amostras dos quartis de alta densidade e as de baixo rendimento foram semelhantes, ambas com baixos valores de S/V (3,99-4,09 e S/G (3,88-4,12 e os mais elevados teores de fenóis totais (13,3-14,3 g de ácido gálico por quilograma. As madeiras do quarto quartil de rendimento são estatisticamente distintas das outras, com as maiores razões S/G (5,15 e S/V (4,98 e os menores teores de fenóis totais (8,7 g de ácido gálico por quilograma. Os parâmetros grupos metoxílicos e açúcares totais são os mais adequados para a diferenciação das amostras provenientes do primeiro quartil de densidade.

Sistemas de información geográfica: aplicación práctica para el estudio de atropellos en el Cercado de Lima, Perú

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Akram Hernández-Vásquez

Full Text Available El objetivo del estudio fue explorar geoespacialmente los patrones de ocurrencia de atropellos en el Cercado de Lima, Perú. Se describieron y georreferenciaron los atropellos registrados en el Censo Nacional de Comisarías 2015 del Instituto Nacional de Estadística e Informática. Posteriormente, se realizó un análisis Kernel Density para localizar áreas con alta, mediana y baja densidad de eventos. Se estudiaron 171 registros de atropellos, los tipos de vehículo involucrados fueron automóvil (56,7% y vehículos menores (22,8%. El mayor porcentaje de atropellos (38,6% ocurrió entre las 12.00-17.00 horas. Se encontraron dos zonas de alta densidad y dos de densidad intermedia para atropellos, coincidiendo con ubicaciones reportadas previamente como críticas por sus deficiencias y mayor probabilidad de accidentes de tránsito. El empleo de sistemas de información geográfica ofrece una visión rápida y general de los patrones de ocurrencia de atropellos, permitiendo realizar comparaciones y facilitaría la implementación de respuestas a nivel local.

Effects of chemical and gamma irradiation environments on the mechanical properties of high-density polyethylene (HDPE)

International Nuclear Information System (INIS)

Soo, P.

1988-01-01

High-density polyethylene (HDPE) is currently being used as a high-integrity container material for low-level wastes. Potential failure/degration modes must be determined for realistic environmental conditions. These include consideration of mechanical stress, gaseous/liquid environments within and external to the container, and the gamma radiation field. A combination of simple inexpensive tests (stressed U-bend samples) and more sophisticated longer-term uniaxial creep tests are being used to define the ranges of conditions for which mechanical failure/degradation is important. Test environments include Igepal CO-630, turbine oil and liquid scintillation fluid as well as air and deionized water, the control environments. Igepal CO-630 is a surfactant specified in standard ASTM tests for environmental stress cracking. Turbine oil is a possible constituent of low-level waste generated at reactor power plants, and is used in the current tests because of its known detrimental behavior to many types of plastic. Liquid scintillation fluids are being evaluated here because they are representative of the class of organiz solvents containing toluene and xylene. As such they will give valuable insights regarding a type of potential failure or degradation mode for HDPE. The effect of gamma irradiation on crack initiation and propagation is also being studied. A description of the work and results are presented. 8 refs., 6 figs., 2 tabs

Evaluasi Kuat Tumpu Alat Sambung Baut pada Papan WPC dari Limbah Sengon dan Plastik HDPE

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Yudhi Arnandha

2016-12-01

Full Text Available Wood Plastic Composite (WPC is wood based material that been produce by mixing sawdust as main composition and plastic polymer as bonding agent. Nowadays, WPC board already been produced in Indonesia using Sengon sawdust and recycle HDPE plastic. Sengon sawdust was used as WPC since its availability from plywood production waste, moreover HDPE plastic considered had higher strength and more rigid than PET plastic. WPC occasionally being used as non structural material, moreover from previous study about mechanical properties of WPC, it was found that WPC Sengon has high shear strength around 25 – 30 MPa. These lead that WPC Sengon had a potential used as shear wall sheathing, thus additional research need to be conducted in order to study the type of bolt and diameter of the bolt can be used for these shear wall. This study aimed to investigate the dowel bearing of bolt using full hole method based on ASTM D5764 with type and bolt diameter as specimen variation. Two types of bolt were used in this study; stainless bolt and standard bolt with diameter each of 6 mm, 8 mm, 10 mm and 12 mm. According to ANOVA, there was insignificant result between stainless bolt and standard one, but there was significant result based on diameter of the bolt. Hereafter, it can be recommended the used of 10 mm diameter of bolt for structural purpose with dowel bearing strength around 67 – 70 MPa.

Assessment of NDE Methods on Inspection of HDPE Butt Fusion Piping Joints for Lack of Fusion with Validation from Mechanical Testing

International Nuclear Information System (INIS)

Anderson, Michael T.; Cinson, Anthony D.; Crawford, Susan L.; Doctor, Steven R.; Moran, Traci L.; Watts, Michael W.

2010-01-01

Studies at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington, are being conducted to evaluate nondestructive examinations (NDE) coupled with mechanical testing of butt fusion joints in high-density polyethylene (HDPE) pipe for assessing lack of fusion. The work provides information to the U.S. Nuclear Regulatory Commission (NRC) on the effectiveness of volumetric inspection techniques of HDPE butt fusion joints in Section III, Division 1, Class 3, buried piping systems in nuclear power plants. This paper describes results from preliminary assessments using ultrasonic and microwave nondestructive techniques and mechanical testing with the high-speed tensile impact test and the side-bend test for determining joint integrity. A series of butt joints were fabricated in 3408, 12-in. IPS DR-11 HDPE material by varying the fusion parameters to create good joints and joints containing a range of lack-of-fusion conditions. Six of these butt joints were volumetrically examined with time-of-flight diffraction (TOFD), phased-array (PA) ultrasound, and the Evisive microwave system. The outer-diameter weld beads were removed for the microwave inspection. In two of the four pipes, both the outer and inner weld beads were removed and the pipe joints re-evaluated. The pipes were sectioned and the joints destructively evaluated with the side-bend test by cutting portions of the fusion joint into slices that were planed and bent. The last step in this limited study will be to correlate the fusion parameters, nondestructive, and destructive evaluation results to validate the effectiveness of what each NDE technology detects and what each does not detect. The results of the correlation will be used in identifying any future work that is needed.

Los profesores de alumnos con altas habilidades

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Cándido GENOVARD

2010-01-01

Full Text Available En este trabajo analizamos las características de los profesores expertos para alumnos de altas habilidades. Se analizan los antecedentes del tema y el proceso instruccional para atender la diversidad de estos alumnos. Se destaca el valor de las interacciones entre profesor¿ alumnos y los estilos de enseñar y aprender. Asimismo, recogemos pautas de acción y recursos instruccionales a utilizar en el aula para la enseñanza de estos alumnos. No hay un profesor ideal para los alumnos con altas habilidades, pero los docentes deben conocer qué son y cómo funcionan los procesos de enseñanza¿aprendizaje y las variables psicológicas, de contenidos y contextuales implicadas en éstos.

Thermal and optical excitation of trapped electrons in high-density polyethylene (HDPE) studied through positron annihilation

International Nuclear Information System (INIS)

Nahid, F.; Zhang, J.D.; Yu, T.F.; Ling, C.C.; Fung, S.; Beling, C.D.

2011-01-01

Positronium (Ps) formation in high-density polyethylene (HDPE) has been studied below the glass transition temperature. The formation probability increases with positron irradiation time due to an increasing number of inter-track trapped electrons becoming available for positron capture. The temperature variation of the saturated Ps level is discussed in different models. The quenching of trapped electrons by light has been studied and the optical de-trapping cross-section for different photon energies has been estimated over the visible region.

Percepción socioemocional de los profesores en adolescentes con altas habilidades versus habilidades medias

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Mari Carmen FERNÁNDEZ

2011-01-01

Full Text Available El objetivo de este trabajo es estudiar la percepción que los profesores tienen sobre las competencias socioemocionales de sus alumnos adolescentes, según la excepcionalidad (alta habilidad vs. no alta habilidad y el género. La muestra estuvo compuesta por 443 profesores pertenecientes a 55 centros de Educación Secundaria Obligatoria de la Región de Murcia. El instrumento utilizado fue el EQ-i, YV-O dirigido a profesores (BAR-ON & PARKER, en prensa. Los resultados indicaron, según la excepcionalidad de los alumnos (alta habilidad vs. no alta habilidad, que los profesores percibieron al grupo de alumnos de alta habilidad más adaptados, con mayor estado de ánimo y con mayores habilidades interpersonales. Respecto al género, los profesores valoraron con mayor manejo del estrés a los chicos. Además, según la excepcionalidad (alta habilidad vs. no alta habilidad y el género, los datos mostraron diferencias estadísticamente significativas para las dimensiones adaptabilidad, estado de ánimo e intrapersonal.

Stocking density of “Pseudoplatystoma” spp. surubim reared in cages Densidade de estocagem do surubim "Pseudoplatystoma" spp. cultivado em tanque-rede

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Daniel Vieira Crepaldi

2009-03-01

Full Text Available This work aimed to determine the effect of stocking density on the biomass production, final weight, feed conversion and survival rate of Pseudoplatystoma spp. surubim reared in floating net cages under three initial stocking densities. Twelve floating net cages located in a 47-ha reservoir were stocked with 35, 70 and 105 fish/m3 averaging 50 g from April to August 1999. At the end of the experimental period (105 days, the final average weights of the treatments were 197.4, 171.15, and 161.45 g, respectively. The highest final mean weight was reached at the lowest initial density. No significant effects of initial stocking density were observed on survival (95.97, 97.80 and 96.73%, respectively and feed conversion rates (1.49; 1.60 e 1.56; respectively. The final biomass of 87.93, 157.67, and 220.46 kg were affected by the initial stocking density. At higher storage densities, the individual weight gain decreased, but the final biomass increased significantly.Objetivou-se com este trabalho determinar o efeito da densidade de estocagem na produção, no ganho de peso, na conversão alimentar e na sobrevivência do surubim Pseudoplatystoma spp. cultivado em tanques-rede, sob três diferentes densidades de estocagem iniciais. Doze tanques-rede foram instalados em uma represa de 47 ha e estocados com 35, 70 e 105 alevinos de surubim/m3, com peso médio de 50g, no período de abril a agosto de 1999. Ao final de 105 dias de experimento, os pesos finais médios para os tratamentos foram 197,4; 171,15 e 161,45 g, respectivamente. O maior peso médio foi alcançado no tratamento de menor densidade. As sobrevivências (95,97; 97,80 e 96,73%, respectivamente e a conversão alimentar (1,49; 1,60 e 1,56:1, respectivamente não foram afetadas pela densidade de estocagem inicial. As biomassas finais foram 87,93; 157,67 e 220,46 kg, respectivamente, com efeito significativo da densidade de estocagem inicial. Com o aumento da densidade de estocagem, houve redu

Formas funcionales del potencial y la densidad electrónica para grafeno delta dopado

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Francisco J. López-Rodríguez

2013-01-01

Full Text Available Establecemos las bases para el estudio del efecto de una línea extendida de impurezas sobre una placa d e grafeno. Mediante el uso de análisis dimensional y la propuesta de una ecuación de Poisson bidimensional, obtenemos las formas funcionales del potencial y la densidad electrónica de este problema.

Research on FR-HDPE/EPDM for cable and wire insulation by γ rays

International Nuclear Information System (INIS)

Jia Shaojin; Zhang Zhicheng; Ge Xuewu; Du Zhiwen; Wang Zhenzhou

2002-01-01

By blending low-halogen flame-retarding agent with the basic resin and using γ irradiation FR-HDPE/EPDM for cable and wire insulation with 125 degree C heat resistance was prepared. The mechanical and electrical measurement showed that radiation crosslinking improves some essential properties of the material, such as the heat resistance, tensile strength et al. The dynamic flammability of the material was researched by cone calorimeter, it was found that radiation crosslinking decreases both release heat rate and effective heat of combustion while burning, besides, crosslinking increases oxygen index and the residues of combustion though the time to ignition of the irradiated material is somewhat decreased. The work was compared with the traditional method TG measurement

Densidad de la madera en clones de Eucalyptus por densitometría de rayos X

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Bibiana Arango

2008-01-01

Full Text Available En el Brasil y en diversos países se han verificado avances significativos en la silvicultura clonal intensiva con diferencias marcadas entre clones de especies e híbridos de Eucalyptus en lo referente a los parámetros de crecimiento y desarrollo. Al mismo tiempo, en los últimos años, se introdujo el concepto de uso múltiplo del leño de los árboles con la utilización de la madera como fuente de celulosa y papel, madera sólida y otras aplicaciones como estrategia de aumento de la rentabilidad del emprendimiento forestal. El presente trabajo tuvo como objetivo determinar el índice de uniformidad de la madera y la variación de la densidad en el sentido radial por densitometría de rayos X de árboles de 8 años de edad de clones de Eucalyptus grandis y E. grandis x urophylla, buscando posibilitar la optimización de su uso. Por sus características silviculturales se seleccionaron los 5 mejores clones de la especie e híbrido de las plantaciones clonales localizadas en el municipio de San Miguel de Arcanjo-SP de la Cia Suzano de Celulosa y Papel. Se caracterizaron 3 modelos de variación radial de la densidad y la formación de 3 tipos de madera (juvenil, de transición y adulta; el valor medio de densidad aparente de la madera en los clones fue de 0,46 y 0,54 g/cm3, para el Eucalyptus grandis y E. grandis x urophylla, respectivamente.

Effect of ionizing radiation exposure in the morphology of modified HDPE with amphiphilic particles; Efeito da exposicao a radiacao ionizante na morfologia de PEAD modificado com particulas anfifilicas

Energy Technology Data Exchange (ETDEWEB)

Saldanha, Ana Luiza M. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil); Vivas, Viviane; Zylberberg, Marcel P.; Silva, Tamara I.; Cardoso, Andre Luis V.; Pereira, Iaci M., E-mail: iacipere@gmail.com [Centro Tecnologico do Exercito (CTEx), Rio de Janeiro, RJ (Brazil); Patricio, Patricia S.O. [Centro Federal de Educacao Tecnologica de Minas Gerias (CEFET), Belo Horizonte, MG (Brazil)

2015-07-01

One of the techniques used to improve the properties of high performance polymers is the addition of hybrid particles in the polymer. In this context, amphiphilic particles were synthesized in order to provide surface characteristics that enhance the interaction of the interface with the polymeric matrix of high density polyethylene (HDPE). The amphiphilic particles were added to matrix of HDPE and the modified polymer composites were exposed to ionizing radiation (x-rays) for different times. The changes caused by exposure to ionizing radiation in the composite morphology was observed through the small angle x-ray technique. The results suggest that the addition of amphiphilic particles increased the stability of the composite to degradation by radiation. (author)

An investigation on morphology and mechanical properties of HDPE/nanoclay/nanoCaCO{sub 3} ternary nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Garmabi, Hamid, E-mail: garmabi@aut.ac.ir; Tabari, Seyed Emad Alavi; Javadi, Azizeh [Department of Polymer Engineering and Color Technology, Amirkabir University of Technology - Tehran - Iran (Iran, Islamic Republic of); Behrouzi, Hormoz; Hosseini, Gholamabbas [Boushehr Province Gas Company - Boushehr - Iran (Iran, Islamic Republic of)

2016-03-09

Ternary Nanocomposites of high-density polyethylene (HDPE) containing two types of nano particles, a layered organoclay (Closite 15A) and a spherical nano Calcium Carbonate (CaCO{sub 3}), with various compositions were prepared using melt mixing. Maleic anhydride grafted polyethylene (MA-g-PE) was used to enhance the dispersion of nanofillers and better interface adhesion. Three different levels of nanoclay (1, 3, 5 wt. %), CaCO{sub 3} (6, 8, 10 wt. %) and MA-g-PE (3, 6, 9 wt. %) were used. The mixing was done in two steps: First a concentrated masterbatch of nanoparticles in HPDE and MA-g-PE was prepared using an internal mixer and then melt-mixing of nanocomposites was done in a lab scale co-rotating twin screw extruder. The morphology of samples was studied using Scanning Electron Microscopy (SEM) and mechanical properties were evaluated using tensile and impact tests. According to the SEM micrographs, nanofillers were well dispersed in the HDPE matrix and XRD patterns showed the intercalation of nanoclay layers too. Generally using the layered nanoclay can enhance the tensile modulus while the use of spherical nano CaCO{sub 3} results into improved toughness. It was found that co-incorporation of these two types of nanofillers, leads to improve the stiffness and minimize the reduction of impact strength, simultaneously.

Stress responses of juvenile matrinxã (Brycon amazonicus after transport in a closed system under different loading densities Respostas de estresse de matrinxã (Brycon amazonicus juvenil após transporte em sistema fechado sob diferentes densidades de carga

Directory of Open Access Journals (Sweden)

Janessa Sampaio de Abreu

2008-08-01

, a temperatura esteve em torno de 32°C, pH 6,5-6,78, a amônia total foi de 1,09-1,7mg L-1, a amônia não-ionizada foi de 3,58-9,33 x 10³mg L-1 e alcalinidade 134-165mg CaCO3 L-1. O cortisol plasmático e a glicose sanguínea aumentaram após o transporte nos peixes em todas as densidades ensaiadas, voltando aos valores controle 24h depois. Os valores de osmolaridade não mudaram logo após o transporte, mas aumentaram 24h depois de modo igual em todas as densidades. O cloreto plasmático diminuiu na chegada, de modo inversamente proporcional à densidade de carga. O hematócrito diminuiu 24h depois da chegada dos peixes, em todas as densidades testadas, mas não houve diferença no número de eritrócitos. Não houve mortalidade até uma semana após o transporte. O matrinxã mostrou ser uma espécie tolerante a altas densidades de carga em embalagens para transporte além de suportar baixos níveis de oxigênio na água.

Blends of ground tire rubber devulcanized by microwaves/HDPE - Part A: influence of devulcanization process

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Fabiula Danielli Bastos de Sousa

2015-06-01

Full Text Available AbstractThe main objective of this work is the study of the influence of microwaves devulcanization of the elastomeric phase on dynamically revulcanized blends based on Ground Tire Rubber (GTR/High Density Polyethylene (HDPE. The devulcanization of the GTR was performed in a system comprised of a conventional microwave oven adapted with a motorized stirring at a constant microwaves power and at various exposure times. The influence of the devulcanization process on the final properties of the blends was evaluated in terms of mechanical, viscoelastic, thermal and rheological properties. The morphology was also studied.

New Supercapacitors of Hybrid Configurations

OpenAIRE

Naoi, Katsuhiko; Naoi, Wako

2013-01-01

[ES] En los últimos años, la mejora de la densidad energética de los nanocompositos empleados en baterías ha sido objeto de un intenso estudio. La unión de un material de baterías y uno de condensadores resuelve las limitaciones de los condensadores de primera generación desde el punto de vista de la densidad energética, sin sacrificar demasiado su comportamiento frente al ciclado. Los híbridos batería-condensador usuales emplean un electrodo redox de alta energía p...

Aplicação de redes neurais na formulação de gorduras para bolo baseada em gorduras interesterificadas de soja e algodão

OpenAIRE

Scaranto, Bruna Antunes Alves

2010-01-01

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias, Programa de Pós-Graduação em Ciência dos Alimentos, Florianópolis, 2010 Os ácidos graxos trans (AGT) na dieta são oriundos principalmente das gorduras parcialmente hidrogenadas. Estudos comprovam que o consumo de AGT ocasiona obesidade, o aumento da lipoproteína de baixa densidade (LDL) em grau similar ao causado pelos ácidos graxos saturados e a diminuição da lipoproteína de alta densidade (HDL)....

Estudio experimental del procesamiento fotónico y térmico de hielos interestelares

OpenAIRE

Jiménez Escobar, Antonio

2013-01-01

El medio interestelar (ISM) es el espacio que hay entre las estrellas, dentro del ISM se puede distinguir el medio difuso, compuesto principalmente por hidrógeno atómico. Si la densidad sigue aumentando se empezarían a formar las nubes moleculares que se componen principalmente por hidrógeno molecular y polvo. Dentro de una nube molecular la densidad de partículas es lo suficientemente alta como para apantallar la región interior de la radiación UV dominante en el ISM, debido a este apantalla...

Determination of thermal and mechanical properties of HDPE-based polymer blends for use in traffic signs

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Benito A. Stradi-Granados

2016-06-01

Full Text Available Two recycled high-density polyethylene specimens and two recycled high-density polyethylene blends were characterized in terms of their thermal and mechanical properties with the purpose of assessing their suitability for the construction of traffic signs. Traffic signs constructed from recycled plastics provide an application for materials that otherwise with end up in landfills. The HDPE composite containing 25% LDPE and 5% ABS had the best mechanical and thermal performance. Of importance is the recycling of ABS that traditionally had not been recycled locally and found its final fate in landfills.

The effects of particle size and content on the thermal conductivity and mechanical properties of Al2O3/high density polyethylene (HDPE composites

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2011-07-01

Full Text Available The influences of filler size and content on the properties (thermal conductivity, impact strength and tensile strength of Al2O3/high density polyethylene (HDPE composites are studied. Thermal conductivity and tensile strength of the composites increase with the decrease of particle size. The dependence of impact strength on the particle size is more complicated. The SEM micrographs of the fracture surface show that Al2O3 with small particle size is generally more efficient for the enhancement of the impact strength, while the 100 nm particles prone to aggregation due to their high surface energy deteriorate the impact strength. Composite filled with Al2O3 of 0.5 µm at content of 25 vol% show the best synthetic properties. It is suggested that the addition of nano-Al2O3 to HDPE would lead to good performance once suitably dispersed.

Variação da densidade básica da madeira de progênies de Eucalyptus urophylla em dois locais.

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Maria Aparecida Mourão Brasil

2009-09-01

Full Text Available Normal 0 21 false false false MicrosoftInternetExplorer4 Estudou-se neste trabalho a variação da densidade básica da madeira entre procedências e progênies de eucalipto plantados em duas localidades. As progênies de Eucalyptus urophylla originárias da ilha de Timor na Indonésia foram plantadas em Belo Oriente (MG e Linhares (ES no delineamento de blocos compactos em famílias (compact family blocks com 3 repetições no espaçamento de 3,0 x 2,0m. Após 4 anos as  árvores  foram amostradas ao nível do DAP com a sonda Pressler e sua densidade básica determinada pelo método do máximo teor de umidade. Os resultados mostraram que as progênies tiveram  comportamento similar nos dois locais. A maior variação entre progênies ocorreu naquelas provenientes da região Oebaha II. Os valores médios de densidade básica* das progênies não foram diferentes das procedências brasileiras utilizadas como testemunhas no experimento.

Aplicación de relaciones de densidad-diámetro y de área potencial aprovechable en bosques de Nothofagus Dombeyi (mirb.) Oerst, como herramientas de planificación silvícola .

OpenAIRE

Cruz Johnson, Pablo Christian

2013-01-01

Uno de los objetivos de esta tesis de doctorado fue analizar la aplicación de relaciones de densidad ¿ diámetro en bosques de Nothofagus dombeyi (Mirb.) oerst, para la localidad del Río Mirta en la XI Región de Chile, como herramientas de planificación silvícola. El método de análisis consistió en la generación de una muestra de densidad¿diámetro a partir de la que se determinó el índice de densidad máximo (IDmax) a partir del cual se estimaron las máximas densidades que la especie podría alc...

Alta Capital investeerib miljardeid kroone / Raigo Neudorf

Index Scriptorium Estoniae

Neudorf, Raigo

2006-01-01

Investeerimisfirma Alta Capital nõukogu esimees Indrek Rahumaa annab ülevaate sellest, kuidas ettevõte on lühikese ajaga suutnud omandada osaluse mitmetes ettevõtetes ning suunanud neisse investeeringuid 150 miljoni euro väärtuses. Vt. samas: Osalused; Omanikud

Influência da densidade de plantio e sistema de podas na produção de café Influence of plant density and pruning system on the yield of coffee

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Sérgio Vasco de Toledo

1999-08-01

Full Text Available Durante 19 anos, foi conduzido um experimento em Campinas, SP, que objetivou avaliar a influência da variedade, espaçamento, número de plantas na cova e sistema de condução da planta sobre a produção de café (Coffea arabica L.. As variedades Mundo Novo e Caturra foram estudadas com cinco densidades de plantio (1, 2, 3, 5 e 6 m²/cova combinadas com uma ou duas plantas por cova e conduzidas sem podas, decotadas a 2 m de altura e recepadas em esquema predeterminado, tipo Beaumont & Fukunaga. Os resultados de 17 colheitas demonstraram que altas densidades de plantio apresentaram elevadas produções nas primeiras safras, com acentuado decréscimo após sete colheitas; a variedade Mundo Novo manteve o potencial produtivo, enquanto a Caturra diminuiu sensivelmente a produção ao longo dos anos; a adoção de um sistema de podas não influenciou na produção, e em alguns períodos foi prejudicial.An experiment with the objective of evaluating the influence of the number of plants per hole, plant density and pruning system on the yield of the Caturra and Mundo Novo varieties of Coffea arabica L. was carried out in Campinas, SP, Brazil, during 19 years. Five planting densities were evaluated: 1, 2, 3, 5 and 6 m²/hole, combined with one and two plants per hole carried out without pruning; pruning at 2 m from the soil; and, plants lapped close to the soil in a regime pre-determinated by Beaumont & Fukunaga. High planting density showed high yields in the first harvests with pronounced decrease after seven harvests. The Mundo Novo variety kept its yield potential while the Caturra variety highly decreased its yield throughout the years; the adoption of a pruning system did not influence the yield and was even prejudicial in some periods.

MÉTODOS DE MEDIÇÃO E ANÁLISE DE DENSIDADE URINÁRIA EM RECÉM-NASCIDOS NA UNIDADE NEONATAL

OpenAIRE

Maria Vera Lúcia Moreira Leitão Cardoso; Gabrielle Gama Teixeira Lima; Leiliane Martins Farias

2013-01-01

El objetivo fue evaluar el método de recolección de orina algodón en contacto con la genital y colector urinario para realización de la densidad urinaria en recién nacidos. Estudio de intervención, cuantitativo, con 61 recién nacidos seleccionados de manera no probabilística. Llevado a cabo en unidad neonatal de Fortaleza-Ceará, Brasil, en 2010. La mayoría nació a término (31/50, 8%) y sexo masculino (33/54%). Los datos de medición de la densidad urinaria con algodón y colector señalaron dife...

Post-{gamma}-irradiation reactions in vitamin E stabilised and unstabilised HDPE

Energy Technology Data Exchange (ETDEWEB)

Mallegol, J.; Carlsson, D.J. E-mail: dave.carlsson@nrc.ca; Deschenes, L

2001-12-01

The oxidation of high density polyethylene (HDPE), both unstabilised and vitamin E stabilised, has been studied by infrared (IR) and electron paramagnetic resonance (EPR) spectroscopies in the period following {gamma}-irradiation at doses from 1 to 60 kGy (range of food sterilisation). Derivatisation by reaction with sulphur tetrafluoride was used to identify macro-ketone and carboxylic acid components of the overlapped IR carbonyl region. Oxidation continued for several hundred hours after the cessation of irradiation as shown by the increase in hydroxyl, ketone and acid groups. Carboxylic acid groups are particularly important as a direct indication of backbone scission. Vitamin E, although an effective antioxidant during {gamma}-irradiation, was less effective in reducing the post-irradiation changes, which are probably driven by migration of radical sites along the polymer backbone from within the crystalline phase to the amorphous/crystalline inter-phase, where they become oxygen accessible.

Bienestar psicológico en personas con alta capacidad intelectual

OpenAIRE

Ramiro Olivier, Pedro; Navarro Guzmán, José I.; Menacho Jiménez, Inmaculada; López Sinoga, M. Mar; García Sedeño, Manuel A.

2016-01-01

El bienestar psicológico en las personas de alta capacidad intelectual ha sido motivo de controversia en la literatura especializada. En ocasiones se ha considerado que estas personas son más proclives a un desajuste psicológico, mientras que otras veces los resultados han sido poco concluyentes. En el presente trabajo se ha estudiado el bienestar psicológico en personas de altas capacidades intelectuales, administrando la Escala de Bienestar Psicológico a 28 participantes de edades comprendi...

Algoritmo recursivo funcional para verificación y monitoreo de la densidad de números primos

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Omar Iván Trejos Buriticá

2016-12-01

Full Text Available El presente artículo formula una solución recursiva, usando programación funcional, para la verificación y monitoreo de la densidad de los números primos que corresponde a la cantidad de números primos que se encuentran en un rango determinado. A partir de este planteamiento se hacen algunas reflexiones en torno a la relación entre matemática y programación de computadores así como alrededor de las tendencias que se notan en la estimación progresiva de la densidad de los números primos cuando se hacen algunas modificaciones en los rangos de evaluación. El propósito de este artículo es poner a consideración de los lectores una solución simple y ágil en la solución del problema planteado así como las reflexiones que de allí se derivan.

Densidad de sitios para anidar y su uso por dos especies de pájaro carpintero (Melanerpes rubricapillus y M. chrysauchen (Piciformes: Picidae en un gradiente urbano de Costa Rica

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Luis Sandoval

2009-11-01

Full Text Available Examiné la densidad de sustratos potencialmente utilizables para anidar por parte de dos especies de pájaros carpinteros (Melanerpes rubricapillus y M. chrysauchen, a lo largo de un gradiente urbano, así como la densidad de sus nidos, haciendo una búsqueda exhaustiva en tres sitios en Golfito, Costa Rica. El área urbana y semi-urbana tuvo la menor densidad de sustratos naturales. La densidad de nidos fue mayor en el área semi-urbana que en los otros dos sitios, posiblemente debido a una mayor abundancia de carpinteros. Los nidos se distribuyeron de forma agrupada, indicando a una mayor preferencia de los carpinteros por anidar en sustratos naturales. Una remoción de los sustratos artificiales podría causar una disminución de la población de ambas especies de carpinteros.

A study of the dynamic flammability of radiation cross-linked flame-retardant HDPE/EPDM/silicon-elastomer compound

Energy Technology Data Exchange (ETDEWEB)

Jia, Shaojin E-mail: jiashaojin2@yahoo.com.cn; Zhang Zhicheng E-mail: zczhang@ustc.edu.cn; Du Zhiwen; Teng Renrui; Wang Zhengzhou

2003-04-01

A dynamic flammability study of flame-retardant compound consisting of HDPE, EPDM and silicon elastomer blended with additives, as wire and cable insulation was made before and after irradiation. The data of RHR, EHC, SEC and the concentration of CO and CO{sub 2} from cone colorimeter shown in the burning process were accessed. By blending silicon elastomer, CO release rate was reduced and the thermal endurance was improved. Oxygen index, mechanical property, morphology of the char formed in dynamical flame and thermal stability were also investigated.

A study of the dynamic flammability of radiation cross-linked flame-retardant HDPE/EPDM/silicon-elastomer compound

International Nuclear Information System (INIS)

Jia, Shaojin; Zhang Zhicheng; Du Zhiwen; Teng Renrui; Wang Zhengzhou

2003-01-01

A dynamic flammability study of flame-retardant compound consisting of HDPE, EPDM and silicon elastomer blended with additives, as wire and cable insulation was made before and after irradiation. The data of RHR, EHC, SEC and the concentration of CO and CO 2 from cone colorimeter shown in the burning process were accessed. By blending silicon elastomer, CO release rate was reduced and the thermal endurance was improved. Oxygen index, mechanical property, morphology of the char formed in dynamical flame and thermal stability were also investigated

TransForm: TransAlta 2000 annual report

International Nuclear Information System (INIS)

2001-01-01

Financial information from TransAlta Corp. was presented along with a review of their operations throughout 2000 and a summary of the how the electric utility is doing in terms of power generation, independent power producers, transmission and energy marketing. The utility has changed from a regulated vertically integrated utility into one of Canada's largest non-regulated electric power generators. The utility sold its retail businesses in Alberta and New Zealand and now focuses on coal and hydro generation, gas generation, high-voltage transmission and energy marketing. The newly constructed Centralia, Washington generation facility was brought on line with 1,340 MW in May 2000, on time and on budget. This was the platform to diversify their generation into the United States. The utility reported a solid financial year with $177.9 million in earnings from continuing operations, an 83 per cent increase from 1999, driven mostly by the results of Centralia and power marketing and trading businesses. A financial loss was suffered when the Wabamum power plant in Alberta was shut down for several months to repair a boiler. The utility made excellent progress toward their goal of 15,000 megawatts by 2005 by starting with the construction of what will be one of Canada's largest cogeneration facilities at Sarnia, Ontario. TransAlta also commissioned a 360 MW cogeneration facility at Poplar Creek at Suncor's Fort McMurray oil sand facility. TransAlta also has an excellent track record in developing power generation projects internationally. refs., tabs., figs

Relaci??n entre la masa muscular, la densidad mineral ??sea, la fuerza muscular, la aptitud funcional y la calidad muscular en personas mayores

OpenAIRE

Pati??o Villada, Fredy Alonso

2015-01-01

294 p. La tesis pretende determinar la frecuencia de la sarcopenia y osteporosis , problemas que afectan a la salud de las personas mayores, y analizar la relaci??n entre la masa muscular, la densidad mineral ??sea (DMO), la fuerza muscular, la aptitud funcional y la calidad muscular (CM). La muestra estudiada fue la formada por un grupo de 83 hombres y 175 mujeres mayores de Le??n (Espa??a). El estudio transversal eval??a ??ndices de masa grasa y densidad mineral ??sea y niveles d...

Performance of juvenile turbot (Scophthalmus maximus fed varying dietary L-carnitine levels at different stocking densities Desempenho de juvenis de pregado (Scophthalmus maximus em função da densidade de estocagem e de níveis dietéticos de L-carnitina

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José Fernando Magalhães Gonçalves

2010-04-01

(75,6 ± 2,8 g alimentados durante 75 dias a dois níveis dietéticos de L-carnitina (40 ou 240 mg kg¹. Após esse período, determinou-se a excreção de amônia pós-prandial durante 24 horas. Os peixes cultivados na menor densidade, 4 kg m², apresentaram melhores taxas de crescimento e ganho de peso (94-96 g em comparação aos mantidos em altas densidades (80-87 g. A taxa de eficiência proteica foi mais elevada a 4 kg m² (1,33-1,36, do que a densidades de 8 kg m² (0,98 ou 14 kg m² (0,45. A ingestão voluntária de alimento decresceu de 0,70 para 0,56% do peso corporal com o incremento da densidade. A suplementação de carnitina não afetou o crescimento e a composição corporal, com exceção do conteúdo de carnitine da carcaça que passou de 75 a 128 mg kg¹. Peixes alimentados com suplementos de 240 mg L-carnitina apresentam excreção de amônia mais baixa comparativamente aos alimentados com 40 mg L-carnitina (p < 0,05.

Neuromielitis óptica con alta expresión de acuaporina-4 y anticuerpos anti-acuaporina-4 positivos en suero

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Alejandra Báez

2012-04-01

Full Text Available La presencia de anticuerpos IgG en suero, con blanco en los canales de acuaporina-4, es específica de la neuromielitis óptica (NMO. El 60% de los pacientes con NMO presentan lesiones cerebrales en la resonancia magnética (RM; en un 8% (mayoría niños estas lesiones se consideraron "atípicas". Presentamos dos pacientes con NMO y lesiones en el SNC de alta expresión de acuaporina-4. Caso 1: varón de 50 años, que comenzó con pérdida de visión en ojo derecho (OD. Recibió tratamiento empírico con metilprednisolona 1 g/d x 3 días. Al mes presentó dolor generalizado y hemiparesia derecha; nuevamente recibió metilprednisolona 1 g/d x 5 días e IgG IV 400 mg/kg/d × 5 días. Recuperó la deambulación persistiendo el dolor y fenómenos paroxísticos en los 4 miembros. Potenciales evocados visuales: P100, ojo izquierdo (OI 123 mseg. OD sin respuesta. La RM de cerebro (FLAIR mostró hiperintensidad en nervio óptico derecho, hipotálamo y comisura blanca anterior. RM cervical: lesión medular extensa (5 cuerpos vertebrales. Caso 2: mujer de 53 años, con disminución de la agudeza visual en ambos ojos y parestesias en miembros inferiores que remitieron espontáneamente. Evolucionó al mes con cuadriparesia e incontinencia esfinteriana. Recibió metilprednisolona 1 g/d x 5 días, sin mejoría. Potenciales evocados visuales: P100 OI 124 mseg. OD 128 mseg. RM cerebro: (FLAIR hiperintensidad hipotalámica y periacueductal. RM cervical: lesión medular extensa (7 cuerpos vertebrales. Anticuerpos anti-acuaporina-4 positivos en ambos pacientes (inmunofluorescencia indirecta. Las lesiones consideradas "atípicas", como aquí, en sitios con alta densidad de proteínas canales de agua AQP4 deberán considerarse para el diagnóstico diferencial.

Comportamiento [del] tanque de material compuesto ante cargas dinámicas

OpenAIRE

Artero Guerrero, José Alfonso

2010-01-01

Este proyecto fin de carrera analiza los impactos de fragmento a alta velocidad sobre estructuras de material compuesto que contienen líquidos. En este proyecto se estudia la vulnerabilidad de la estructura cuando está fabricada en material compuesto. Las excelentes propiedades que tienen los plásticos reforzados de fibras de carbono en cuanto a baja densidad y alta resistencia mecánica los sitúan en una situación clave para desarrollarse como material estructural en fabricación de aviones. E...

Alta Capital venitab Kruudale tasumisega / Sten-Aleks Pihlak

Index Scriptorium Estoniae

Pihlak, Sten-Aleks

2008-01-01

Alta Capital Partnersid pole veel maksnud Oliver Kruudale 2007. aasta septembris müüdud Tere ja Kalevi eest. Vt. samas: Rahasaamise venimine on lükanud Kalevi viimastel kuudel laenurallile. Kommenteerib Aivar Häelm

Desarrollo de un sistema de suspensión magnética para la determinación de densidad de líquidos

OpenAIRE

Centeno González, Luz María; Castillo Castañeda, Eduardo; Becerra Santiago, Luis Omar; Rochín García, Alberto

2013-01-01

La densidad es una magnitud derivada de las magnitudes de base masa y longitud, está definida como masa por unidad de volumen y su unidad en el Sistema Internacional de Unidades (SI) es el kg/m3. En las últimas cinco décadas, en el ámbito de la metrología primaria, se han desarrollado sistemas de suspensión magnética para la determinación de densidad de fluidos, lo que ha permitido realizar investigaciones sobre las características físicas de líquidos y gases. El presente trabajo tiene como o...

Rejuvenecimiento de manos con ácido hialurónico de alta densidad: estudio prospectivo en 29 pacientes Hands rejuvenation with high density hyaluronic acid: prospective study in 29 patients

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J.M. Alcolea

2012-12-01

Full Text Available El objetivo del presente estudio prospectivo es valorar a corto, medio y largo plazo, la eficacia en el rejuvenecimiento de las manos de la inyección subcutánea de ácido hialurónico (AH, Macrolane® 20, de alta densidad y partículas grandes, teniendo en cuenta el beneficio del tratamiento, la satisfacción de los pacientes y las posibles complicaciones. Este estudio se realizó entre mayo del 2010 y diciembre del 2011. Se seleccionaron 29 pacientes al azar entre 51 y 74 años de edad con fototipos II a IV, a los que se les inyectó AH para rejuvenecer las manos. La cantidad de AH inyectada en cada mano fue de 1 a 2 ml. Se realizaron controles sistemáticos en la 2ª semana, en los meses 1º, 3º, 6º, 9º y 12º. Se tuvieron en cuenta las complicaciones en cada paciente en todos los controles. En el primer control, en la 2ª semana, junto al examen clínico se practicó examen ecográfico a fin de determinar si sería necesaria una segunda inyección de AH. En cada uno de los controles los pacientes contestaron a un formulario para indagar sobre su grado de satisfacción con el tratamiento. Solo 1 paciente presentó edema y 3 tuvieron equimosis leve; 2 pacientes manifestaron dolor leve con las inyecciones y 2 requirieron una segunda inyección tras la valoración en la 2ª semana. La satisfacción de los pacientes en los controles superó la valoración clínica y fotográfica. En nuestra opinión, el rejuvenecimiento de las manos con este tipo de AH de grandes partículas tiene una baja tasa de complicaciones y es bien tolerado, con un alto grado de satisfacción por parte de los pacientes y una notable mejoría de los parámetros estudiados: arrugas, aspecto de la atrofia dérmica y subcutánea y disminución de los relieves óseos, tendinosos y venosos. La valoración tanto subjetiva como objetiva se hizo hasta el año de seguimiento con buenos resultados.The aim of this prospective study is to assess the efficacy of a high density

LA DENSIDAD Y TAMAÑO DE PLÁNTULAS CON CEPELLÓN EN LA PRODUCCIÓN DE ESPÁRRAGO VERDE

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Ana Mar\\u00EDa Castagnino

2011-01-01

Full Text Available Con el objetivo de determinar la influencia del tamaño de la celda utilizada para la obtención de plántulas de espárrago y la densidad o marco de plantación empleado, sobre la producción de turiones, se evaluó en invernadero tres tamaños de celda: 1 PG: grande (70 cm3, 2 PM: mediana (30 cm3 y 3 PCh: pequeña (20 cm3 y tres densidades (35 714 (D1; 23 810 (D2 y 17 857 (D3 plantas/ha. Se efectuó un trabajo en la Chacra Experimental de la Facultad de Agronomía, en Azul, provincia de Buenos Aires. La plantación en el campo se efectuó en noviembre 2002, setenta días después de la siembra del almácigo con plántulas con cepellón. La cosecha se realizó del 25/09 al 18/10 del año 2006, en el cuarto año desde la plantación, con una frecuencia de cosecha de día por medio. Se realizó un análisis de la varianza, con un diseño completamente al azar y considerando como factor: el tamaño de las plántulas que provenían de cada contenedor y tres densidades. En el segundo año evaluado, la densidad D1 fue la de mayor producción (4450 kg/ha netos totales y mayor cantidad de turiones (380 166. Las plantas provenientes de los dos mayores tamaños de celda produjeron 4 t/ha netas en promedio. Las bandejas de siembra de tamaño G y D1 resultaron más apropiados para la producción de espárrago ya que permitieron obtener el mayor rendimiento en peso y número, y obtener un mejor aparato radical.

Propiedades mecánicas del telururo de bismuto (Bi2Te3 procesado mediante torsión bajo alta presión (HPT

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Santamaría, Jon Ander

2013-06-01

Full Text Available Bismuth telluride, Bi2Te3, is the main thermoelectric material currently in use for commercial cooling devices or for energy harvesting near room temperature. Because of its highly anisotropic layered structure, Bi2Te3 is very brittle, failing by cleavage along its basal plane. Refining its grain size is expected to increase its toughness with the advantage that, simultaneously, its thermoelectric “figure of merit” results increased. In this work, powders of the compound have been compacted by conventional methods as well as by severe plastic deformation under high pressure (3 GPa using high pressure torsion (HPT, one turn at room temperature. Near-theoretical density has been achieved. The hardness and toughness of the compacts have been assessed by micro and nano-indentation.Actualmente el telururo de bismuto (Bi2Te3 es el material termoeléctrico más ampliamente usado en sistemas de refrigeración comerciales o en la conversión de energía en torno a temperatura ambiente. Debido a su estructura laminar altamente anisótropa, el Bi2Te3 es muy frágil y suele agrietarse fácilmente a lo largo de su plano basal. Se espera que el afino del tamaño de grano incremente su tenacidad, con la ventaja de que al mismo tiempo la figura de mérito termoeléctrica se vea incrementada. En este trabajo, polvos del compuesto Bi2Te3 se han compactado mediante dos métodos convencionales y mediante deformación plástica severa bajo alta presión (3 GPa usando la técnica HPT (torsión a alta presión, 1 giro de deformación. Se ha conseguido una densidad cercana a la teórica. La dureza y tenacidad de los compuestos se han ensayado mediante micro- y nano- indentación.

Pilot-Scale Demonstration of ALTA for NOx Control in Pulverized Coal-Fired Boilers

Energy Technology Data Exchange (ETDEWEB)

Andrew Fry; Devin Davis; Marc Cremer; Bradley Adams

2008-04-30

This report describes computational fluid dynamics (CFD) modeling and pilot-scale testing conducted to demonstrate the ability of the Advanced Layered Technology Approach (ALTA) to reduce NO{sub x} emissions in a pulverized coal (PC) boiler. Testing specifically focused on characterizing NO{sub x} behavior with deep burner staging combined with Rich Reagent Injection (RRI). Tests were performed in a 4 MBtu/hr pilot-scale furnace at the University of Utah. Reaction Engineering International (REI) led the project team which included the University of Utah and Combustion Components Associates (CCA). Deep burner staging and RRI, combined with selective non-catalytic reduction (SNCR), make up the Advanced Layered Technology Approach (ALTA) for NO{sub x} reduction. The application of ALTA in a PC environment requires homogenization and rapid reaction of post-burner combustion gases and has not been successfully demonstrated in the past. Operation of the existing low-NO{sub x} burner and design and operation of an application specific ALTA burner was guided by CFD modeling conducted by REI. Parametric pilot-scale testing proved the chemistry of RRI in a PC environment with a NOx reduction of 79% at long residence times and high baseline NOx rate. At representative particle residence times, typical operation of the dual-register low-NO{sub x} burner provided an environment that was unsuitable for NO{sub x} reduction by RRI, showing no NOx reduction. With RRI, the ALTA burner was able to produce NO{sub x} emissions 20% lower than the low-NO{sub x} burner, 76 ppmv vs. 94 ppmv, at a burner stoichiometric ratio (BSR) of 0.7 and a normalized stoichiometric ratio (NSR) of 2.0. CFD modeling was used to investigate the application of RRI for NO{sub x} control on a 180 MW{sub e} wall-fired, PC boiler. A NO{sub x} reduction of 37% from baseline (normal operation) was predicted using ALTA burners with RRI to produce a NO{sub x} emission rate of 0.185 lb/MBtu at the horizontal nose of

Respostas lactacidêmicas de ratos ao treinamento intermitente de alta intensidade

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Ana Carolina Panveloski-Costa

2012-04-01

Full Text Available Durante contrações musculares de alta intensidade intervaladas por curtos períodos de tempo há importante participação do metabolismo glicolítico e, consequentemente, aumento das concentrações de lactato sanguíneo. O objetivo do estudo foi avaliar as respostas lactacidêmicas agudas e crônicas de ratos Wistar submetidos a um treinamento intermitente de alta intensidade (salto tipo jump squat de três sessões semanais, a cada 24h, três séries de 12 repetições com intervalos de 60s entre cada uma. Houve aumento das concentrações de lactato sanguíneo durante a sessão aguda do treinamento (lactacidemia basal vs. lactacidemia após último esforço, P < 0,001. Contrariamente, após seis semanas de treinamento, ocorreu redução de 49% na resposta lactacidêmica ao exercício em relação à primeira sessão, P = 0,0002. O exercício intermitente de alta intensidade intervalado favorece a participação do sistema glicolítico; no entanto, o treinamento intermitente de alta intensidade promove redução das respostas lactacidêmicas, sugerindo melhora da capacidade de ressíntese de fosfocreatina e da biogênese mitocondrial.

Sostenibilidad de sistemas ganaderos bovinos de alta montaña en Colombia

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Raúl Andrés Molina Benavides

2017-09-01

Full Text Available La complejidad de los sistemas agropecuarios dadas sus múltiples interacciones de elementos bióticos y abióticos, hace que estudios integrales sean importantes para un mejor entendimiento y actuación frente a éstos. Este trabajo tuvo como objetivo estudiar la sostenibilidad de 8 sistemas ganaderos alto andinos. Se encontró en promedio carga animal de 0,5 UGG, producción de leche de 4 kg/vaca/día, intervalos de partos de 450 días y producciones de forraje de 2,45 t MS/ha con 14% PC y 60% FDN. En promedio para el bosque, el carbono orgánico del suelo fue de 33,72 t/ha y para los potreros de pastoreo de 25,29 t/ha, siendo significativa la diferencia (p≤0,05. No se encontró diferencias (p≥0,05 entre las densidades aparentes en el suelo de los bosques nativos (0,46g/cm3 y los potreros (0,5 g/cm3. Las cantidades de CO2 equivalente (CO2eq producidas en promedio  fueron de 76,12 t/predio (65,5 t CO2eq correspondientes a la producción de CH4 y 10,87 t CO2eq a la producción de N2O. El agua virtual requerida en promedio para los bovinos fue de 16.222,26 m3 para cubrir sus necesidades de alimento, bebida y servicios (10 años, y para producir un litro de leche requerían 1,78 m3. En el aspecto social los indicadores con menor calificación fueron servicios públicos y acceso a educación. En conclusión y sabiendo que la sostenibilidad se logra cuando hay un balance entre los componentes económico, ambiental y social; los resultados encontrados permiten afirmar que los sistemas productivos ganaderos de alta montaña incluidos en este trabajo no son sostenibles.

Cobertura plástica e densidade de plantio na qualidade das frutas de Physalis peruviana L.

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Pedro Henrique Abreu Moura

2016-06-01

Full Text Available RESUMO Physalis peruviana L. é uma espécie pertencente à família Solanaceae, que vem sendo incorporada em plantios de pequenas frutas, com alto potencial produtivo para regiões subtropicais. Objetivou-se, com este trabalho, avaliar a qualidade das frutas de P. peruviana L., produzidas com ou sem cobertura plástica sobre o dossel das plantas e em duas densidades de plantio (0,5 e 1,0 m entre plantas, sendo de 3,0 m o espaçamento entre linhas. O delineamento experimental adotado foi em blocos ao acaso, em esquema fatorial 2 x 2, com seis blocos e dez plantas por parcela. Foram avaliadas as características qualitativas das frutas, como coloração, quantidade de antocianinas totais, vitamina C, cinzas, sólidos solúveis totais, sacarose, glicose, açúcares totais, acidez titulável, firmeza e umidade. A maior densidade de plantio e o plantio sem cobertura plástica sobre o dossel das plantas resultaram em melhor qualidade das frutas de P. peruviana L.

Aislamiento e identificación de hongos asociados a esclerocios de Sclerotium cepivorum, causante de la pudrición blanca de la cebolla, en la zona alta de Cartago, Costa Rica

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María del Milagro Granados

2005-01-01

Full Text Available Se aislaron e identificaron hongos asociados a esclerocios de Sclerotium cepivorum, causante de la pudrición blanca de la cebolla, con el fin de determinar la existencia de hongos con potencial antagónico nativos en la zona alta de Cartago. Se estudiaron 10 fincas durante febrero-mayo de 2002. Cada una se dividió en 3 áreas de acuerdo al nivel de incidencia histórica de la enfermedad (bajo, intermedio, alto. En cada área se realizó un trampeo de hongos mediante la técnica de entierro de esclerocios; además se hizo muestreo de plantas enfermas, se colectó suelo para cuantificar densidad de inóculo y para realizar análisis microbiológicos, químico sencillo, de textura y determinación de materia orgánica. Los géneros encontrados en el trampeo fueron Alternaria spp., Fusarium spp., Gliocladium sp., Mucor sp., Penicillium spp., Rhizoctonia sp., Rhizopus sp. y Trichoderma spp.; en bulbos enfermos se aislaron Fusarium spp., Monilia sp., Mucor sp., Penicillium spp., Pythium sp., Rhizopus sp., y Trichoderma spp. Los géneros Gliocladium sp., Penicillium spp. y Trichoderma spp. también se hallaron en el análisis microbiológico de suelo. Las poblaciones más altas de microorganismos se recuperaron en el área intermedia de todas las fincas. Este trabajo comprueba que es posible aislar hongos con potencial antagónico, como Trichoderma spp., Gliocladium sp. y Paecilomyces sp., en suelos a los que por muchos años se les ha aplicado una gran cantidad de fungicidas.

High intensity Discharge lighting; Alumbrado de alta intensidad de descarga

Energy Technology Data Exchange (ETDEWEB)

Mendoza E, Ernesto J [Manufacturera de Reactores, S. A., Mexico, D. F. (Mexico)

1994-12-31

This paper gets into contact with some fundamentals in the operation of high discharge intensity lamps. There are useful definitions, as well as the study of the operation of high pressure sodium lamps and of metallic additives operating at less than nominal power. [Espanol] Este trabajo pone al lector en contacto con algunos fundamentos de la operacion de las lamparas de alta intensidad de descarga (HID). Se encuentra con definiciones utiles, asi como el estudio de la operacion de las lamparas de sodio en alta presion y de aditivos metalicos operando a una potencia menor que la nominal.

High intensity Discharge lighting; Alumbrado de alta intensidad de descarga

Energy Technology Data Exchange (ETDEWEB)

Mendoza E, Ernesto J. [Manufacturera de Reactores, S. A., Mexico, D. F. (Mexico)

1993-12-31

This paper gets into contact with some fundamentals in the operation of high discharge intensity lamps. There are useful definitions, as well as the study of the operation of high pressure sodium lamps and of metallic additives operating at less than nominal power. [Espanol] Este trabajo pone al lector en contacto con algunos fundamentos de la operacion de las lamparas de alta intensidad de descarga (HID). Se encuentra con definiciones utiles, asi como el estudio de la operacion de las lamparas de sodio en alta presion y de aditivos metalicos operando a una potencia menor que la nominal.

Participação do colmo principal e dos afilhos na produtividade do arroz irrigado, em função da densidade de semeadura

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Eduardo do Valle Lima

2010-01-01

Full Text Available Entre as práticas culturais a serem consideradas na implantação da cultura do arroz destaca-se a densidade de semeadura, que deve estabelecer, em grande parte, a participação do colmo principal e dos afilhos nos componentes da produção, possibilitando a obtenção da máxima produtividade. O trabalho teve como objetivo avaliar a participação do colmo principal e dos afilhos na produtividade de grãos de arroz, cv. IAC 102, no sistema irrigado por inundação, em função da densidade de semeadura. O experimento foi desenvolvido sob túnel plástico, em Botucatu (SP, em caixas d'água de cimento amianto de 500 L, contendo Neossolo Flúvico Ta Eutrófico, com profundidade de 30 cm. O delineamento experimental foi o inteiramente casualizado, com quatro repetições. As densidades de semeadura foram: 100, 200, 300, 400, 500 e 600 sementes viáveis por m², em 4 linhas de 1 m por caixa, espaçadas com 20 cm. A elevação da densidade de semeadura diminui o afilhamento e proporciona a maior participação dos colmos principais, porém, não resultando em incremento de produtividade, devido à plasticidade das plantas de arroz, que proporciona o ajustamento dos componentes da produção.

Densidade das células do endotélio corneano em olhos de cães à microscopia especular

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João Antonio Tadeu Pigatto

2006-08-01

Full Text Available Objetivou-se examinar a superfície posterior do endotélio corneano e realizar análise morfométrica das células endoteliais da córnea de olhos normais de cães à microscopia especular. Procedeu-se à morfometria avaliando-se a área celular média e a densidade endotelial. Ambos os olhos de dez cães, sem raça definida, machos ou fêmeas, com 6 anos de idade, com peso médio de 15 kg, eutanasiados por razões não relacionadas a este estudo foram estudados. Os olhos foram avaliados para determinar as condições de higidez e transportados ao laboratório em câmara úmida. Valendo-se de microscópio especular de contato o endotélio corneano foi examinado. Obteve-se 3 imagens da região central de cada córnea. Realizou-se a análise morfométrica valendo-se de software adequado para determinação da área celular média e da densidade endotelial. A área celular média foi 395 ± 36 µm² e a densidade endotelial 2555 ± 240 células/mm². O presente estudo demonstrou que o endotélio de bulbos oculares normais de cães é similar ao endotélio de indivíduos da espécie humana.

Effect of TiO2 photocatalytic activity in a HDPE-based food packaging on the structural and microbiological stability of a short-ripened cheese.

Science.gov (United States)

Gumiero, Matteo; Peressini, Donatella; Pizzariello, Andrea; Sensidoni, Alessandro; Iacumin, Lucilla; Comi, Giuseppe; Toniolo, Rosanna

2013-06-01

A high density polyethylene (HDPE)/calcium carbonate (CaCO(3)) film containing TiO(2) was prepared via blown film extrusion process. The photocatalytic properties of this film were evaluated by voltammetric, UV-Vis spectrophotometric and gas chromatographic measurements following the decomposition rate of suitably selected molecular probes, such as 4-hydroxybenzoic acid and methylene blue. The film containing 1% w/w of TiO(2) displayed a profitable and reproducible photoinduced degradation activity towards target organic compounds. The effect of packaging photocatalytic activity on the structural and microbiological stability of a short-ripened cheese was studied. Cheese structure was assessed by dynamic, small deformation rheological tests. A container consisting of a multilayer material, where the layer brought in contact with the food, made from the HDPE+CaCO(3)+TiO(2) composite matrix, was able to provide a greater maintenance of the original cheese structure than a rigid container currently used, mainly due to the inhibition of lactic acid bacteria and coliforms. Copyright © 2012 Elsevier Ltd. All rights reserved.

diferentes idades e densidades populacionais

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César Martins Andrade

2007-01-01

Full Text Available The variation of the annual growth in different heights of the stem of Pinus taeda L. was studied through the stem analysis, accomplished in dominant and medium stratum trees. Cross sections were collected along the stem from 9 sample trees on the base, breast height diameter (BHD and after these positions, at every meter. The sampling was constituted of 4 trees coming from Canela, Rio Grande do Sul, in a 17-years-old stand, submitted to one thinning, and 6 trees from Ponte Alta do Norte, Santa Catarina, in a 34-years-old stand, submitted to five thinnings. The results, expressed in percentage of the basal area increment in several positions of the tree height, showed strong variation in the annual deposition of wood along the stem in function of the populational density, characterizing the effects of the competition and of the thinning liberation. Trees subjected to the competition showed larger growth on top parts of the stem, while trees under smaller competition presented larger growth on lower positions, easily identified by the form and inclination of the increment curves.

CAMBIOS EN LA ESTRUCTURA DE LA POBLACIÓN DE Boeckella gracilis (CRUSTACEA, CENTROPAGIDAE EN EL PLANCTON DEL LAGO DE TOTA, BOYACÁ - COLOMBIA

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ADRIANA DEL PILAR GONZÁLEZ ANGARITA

2008-05-01

Full Text Available Se realizó un seguimiento a la población de Boeckella gracilis Daday, 1902 en el lago de Tota, Boyacá, Colombia, durante seis meses con periodicidad quincenal a partir de mayo de 2004. La densidad poblacional fue de 11.968 Ind.m-3 en promedio y expresó un incremento progresivo hasta el final del estudio que corresponde a época de fuertes lluvias en la zona y aguas altas en el lago. Los machos adultos dominaron en densidad y biomasa, constituyendo el 32,5% y el 35,8% de la población, respectivamente. La fecundidad promedio se estimó en 0,32 huevos por hembra. En la época de aguas altas se presentó un aumento de la actividad reproductiva evidenciado por el incremento de la fecundidad y el mayor número de copepoditos. Con base en el análisis de componentes principales, la transparencia, el pH y el oxígeno disuelto fueron las variables determinantes de la expresión temporal del hábitat. El comportamiento de la biomasa de la población se asoció positivamente con la variación de la densidad de los adultos y copepoditos y negativamente con la concentración de oxígeno disuelto en el lago.

Mechanical properties of chemically modified Sansevieria trifasciata/natural rubber/high density polyethylene (STF/NR/HDPE) composites: Effect of silane coupling agent

Science.gov (United States)

Zakaria, Nurzam Ezdiani; Baharum, Azizah; Ahmad, Ishak

2018-04-01

The main objective of this research is to study the effects of chemical modification on the mechanical properties of treated Sansevieria trifasciata fiber/natural rubber/high density polyethylene (TSTF/NR/HDPE) composites. Processing of STF/NR/HDPE composites was done by using an internal mixer. The processing parameters used were 135°C for temperature and a mixing rotor speed of 55 rpm for 15 minutes. Filler loading was varied from 10% to 40% of STF and the fiber size used was 125 µm. The composite blends obtained then were pressed with a hot press machine to get test samples of 1 mm and 3 mm of thickness. Samples were evaluated via tensile tests, Izod impact test and scanning electron microscopy (SEM). Results showed that tensile strength and strain value decreased while tensile modulus increased when filler loading increased. Impact strength increased when filler loading increased and began to decrease after 10% of filler amount for treated composites. For untreated composites, impact strength began to decrease after 20% of filler loading. Chemical modification by using silane coupling agent has improved certain mechanical properties of the composites such as tensile strength, strain value and tensile modulus. Adding more amount of filler will also increase the viscosity and the stiffness of the materials.

Characterization of Alkaline Treatment and Fiber Content on the Physical, Thermal, and Mechanical Properties of Ground Coffee Waste/Oxobiodegradable HDPE Biocomposites

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Ming Yee Tan

2017-01-01

Full Text Available Effect of alkali treatment on ground coffee waste/oxobiodegradable HDPE (GCW/oxo-HDPE composites was evaluated using 5%, 10%, 15%, and 20% volume fraction of GCW. The composites were characterized using structural (Fourier transform infrared spectroscopy (FTIR and scanning electron microscopy (SEM, thermal (thermogravimetric analysis (TGA and differential scanning calorimetry (DSC, mechanical (tensile and impact test properties, and water absorption. FTIR spectrum indicated the eradication of lipids, hemicellulose, lignin, and impurities after the treatments lead to an improvement of the filler/matrix interface adhesion. This is confirmed by SEM results. Degree of crystallinity index was increased by 5% after the treatment. Thermal stability for both untreated and treated GCW composites was alike. Optimum tensile result was achieved when using 10% volume fraction with enhancement of 25% for tensile strength and 24% for tensile modulus compared to untreated composite. Specific tensile strength and modulus had improved as the composite has lower density. The highest impact properties were achieved when using 15% volume fraction that lead to an improvement of 6%. Treated GCW composites show better water resistance with 57% improvement compared to the untreated ones. This lightweight and ecofriendly biocomposite has the potential in packaging, internal automotive parts, lightweight furniture, and other composite engineering applications.

Diffusione molecolare neLl' alta atmosfera

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C. ARDUINI

1963-06-01

Full Text Available Le perturbazioni indotte nell'alta atmosfera dall'emissione,
a mezzo di razzi sonda, di nubi di vapori estranei sono un utile
mezzo per lo studio simultaneo di alcune caratteristiche fisiche e dinamiche
degli alti strati.
La presente relazione illustra in breve i principi di alcune tecniche
per la misura del coefficiente di diffusione binaria tra l'aria e il vapore
della nube artificiale.

Un modelo educativo de adaptación curricular en alumnos de altas capacidades

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Celestino RODRÍGUEZ

2010-01-01

Full Text Available En base a la legislación educativa española vigente, las altas capacidades se incluyen en el marco de las necesidades educativas específicas de apoyo educativo. En el presente estudio ejemplificamos una propuesta de adaptación curricular individual para alumnos con altas capacidades, que pretende promover el desarrollo equilibrado de los objetivos de aprendizaje propuestos en su programación de aula. Todo ello, a través de una descripción por pasos del proceso, partiendo de una evaluación previa de las altas capacidades, una planificación de la intervención educativa, una propuesta educativa concreta (ejemplificada en el área de Lengua castellana y el desarrollo de programas complementarios.

URBANIZAÇÃO EFETIVA E DENSIDADE DE DOMICÍLIOS NA REGIÃO OCEÂNICA DE NITERÓI (RJ ENTRE 1976 E 2010

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Thiago Henriques Fontenelle

2013-03-01

Full Text Available A Região Oceânica do município de Niterói (RJ tem sido objeto de intensa especulação imobiliária nas últimas décadas, associando o ideário de paisagens naturais e qualidade de vida a um modelo de habitações predominantemente voltado para população de alto padrão aquisitivo. Neste sentido, este trabalho objetiva analisar a expansão tanto do perímetro urbano como da densidade de domicílios da região no período entre 1976 e 2010, associando ainda a situação atual com o zoneamento urbano-ambiental vigente. A análise histórica, a geoestatística e um conjunto variado de geotecnologias foram as principais ferramentas utilizadas para produção e análise de dados. Em conjunto com estas ferramentas, é proposta uma metodologia alternativa de tratamento de dados censitários e avaliação de densidades de domicílios por unidade de área. Os resultados demonstram o crescimento de 112% da área urbanizada da Região Oceânica, enquanto o número de domicílios cresceu na ordem de 600%, remontando ao processo interligado de avanço tanto via expansão em área quanto via aumento de densidade. Em comparação com o zoneamento, há esgotamento para incorporação de novas áreas perimetrais, o que aponta para um aprofundamento ainda maior do aumento de densidades demográficas nas próximas décadas assim como da pressão sobre os geossistemas costeiros.

Efeito da densidade máxima teórica na dosagem e no comportamento mecânico de mistura asfáltica tipo CBUQ

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Kamilla Lima Vasconcelos

2009-12-01

Full Text Available

A partir da densidade aparente dos agregados, da densidade aparente do corpo-de-prova compactado e da densidade máxima teórica (DMT determinam-se as características volumétricas de uma mistura asfáltica e, em vários métodos, sua dosagem quanto ao teor de ligante a ser empregado. Diferentes procedimentos na determinação da DMT podem levar a resultados distintos, acarretando em parâmetros volumétricos também distintos. No Brasil, a DMTé comumente calculada através de uma ponderação das densidades reais dos materiais constituintes da mistura. Neste trabalho, além do cálculo da DMT, são investigados dois procedimentos de laboratório para sua determinação: (i norma americana ASTM D 2041, que utiliza uma bomba de vácuo (método Rice e, (ii método utilizando querosene. São discutidas possíveis diferenças nos valores de DMT obtidos pelos procedimentos, avaliando a influência das diferenças nos parâmetros volumétricos e, conseqüentemente, na escolha do teor de projeto. Por fim, o comportamento mecânico das misturas cujo teor de ligante foi determinado pelos três métodos foi avaliado por meio dos ensaios de resistência à tração, módulo de resiliência e vida de fadiga a tensão controlada.

A study on residual stress mitigation of the HDPE pipe for various annealing conditions

Energy Technology Data Exchange (ETDEWEB)

Kim, Jong Sung [Sunchon National University, Sunchon (Korea, Republic of); Yoo, Jeong Ho [Korea Laboratory Engineering System, Daejeon (Korea, Republic of); Oh, Young Jin [KEPCO E and C, Sungnam (Korea, Republic of)

2015-03-15

This paper presents effects of the annealing condition variables such as temperature and time on the residual stress mitigation. The effects were investigated by using the various measurement methods such as hole-drilling method and slitting method. As a result of the investigation, the residual stress mitigation magnitude increases with increasing the annealing time and temperature. Based on the investigation results, the quantitative correlations between the annealing variables and the residual stress mitigation were derived. Finally, the effect of long-term operation under the normal operating temperature conditions on the residual stress mitigation was investigated by referring to the derived equations and performing some additional tests, and it is identified that the residual stresses are not significantly relaxed over the design lifetime of the safety class III buried HDPE pipes.

Optimization of Injection Molding Parameters for HDPE/TiO₂ Nanocomposites Fabrication with Multiple Performance Characteristics Using the Taguchi Method and Grey Relational Analysis.

Science.gov (United States)

Pervez, Hifsa; Mozumder, Mohammad S; Mourad, Abdel-Hamid I

2016-08-22

The current study presents an investigation on the optimization of injection molding parameters of HDPE/TiO₂ nanocomposites using grey relational analysis with the Taguchi method. Four control factors, including filler concentration (i.e., TiO₂), barrel temperature, residence time and holding time, were chosen at three different levels of each. Mechanical properties, such as yield strength, Young's modulus and elongation, were selected as the performance targets. Nine experimental runs were carried out based on the Taguchi L₉ orthogonal array, and the data were processed according to the grey relational steps. The optimal process parameters were found based on the average responses of the grey relational grades, and the ideal operating conditions were found to be a filler concentration of 5 wt % TiO₂, a barrel temperature of 225 °C, a residence time of 30 min and a holding time of 20 s. Moreover, analysis of variance (ANOVA) has also been applied to identify the most significant factor, and the percentage of TiO₂ nanoparticles was found to have the most significant effect on the properties of the HDPE/TiO₂ nanocomposites fabricated through the injection molding process.

High density of defoliated tomato plants in protected cultivation and its effects on development of trusses and fruits Alta densidade com desfolhamento de plantas de tomateiro em cultivo protegido e seus efeitos sobre o desenvolvimento de inflorescências e frutos

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Miguel A. Sandri

2002-09-01

ground area seems to be the upper limit in maximizing the number of set fruits of this crop.O número de frutos em plantas de tomateiro cultivadas em alta densidade e com índice de área foliar similar mantido através de desfolhamento foi determinado em três condições ambientais, no interior de túneis de polietileno. O experimento 1 foi conduzido no outono, com radiação solar média recebida pela cultura de 8,0 MJ m-2 dia-1 e temperatura média exterior de 18,1ºC. Os experimentos 2 e 3 foram conduzidos na primavera, com temperatura média exterior de 19,7ºC. No experimento 2, a radiação solar média recebida pela cultura foi de 12,4 MJ m-2 dia-1, enquanto no experimento 3 foi reduzida para 5,9 MJ m-2 dia-1 por meio de uma tela com 52% de sombreamento. As plantas foram cultivadas em sacolas, com 1,0 m entre fileiras e 0,3 m entre sacolas, enchidas com 5,5 L de substrato comercial. Nutrientes e água foram fornecidos via solução nutritiva, de forma a repor os volumes perdidos pela transpiração. Os tratamentos consistiram de uma (T1, duas (T2 e três (T3 plantas por sacola, correspondendo a densidades de 3,3; 6,7 e 10 plantas m-2, respectivamente. Em T1, três folhas por simpódio foram mantidas, com uma proporção de 3:1 entre o número de folhas e de inflorescências, em cada simpódio. Em T2, duas e uma folha foram mantidas respectivamente em dois simpódios consecutivos, alternativamente em ambas as plantas da sacola. A relação entre o número de folhas e de inflorescências foi de 3:2. Em T3, com três plantas por sacola, somente uma folha por simpódio foi mantida, com uma relação de 3:3. Em todos os experimentos, o número de inflorescências por unidade de área em T2 e T3 foi duas e três vezes maior que em T1, respectivamente. O número de frutos fixados por área de solo foi menor em T1 e similar em T2 e T3 no primeiro experimento, enquanto no segundo e terceiro experimentos valores similares foram observados entre os tratamentos. Os

PHOBOS at RHIC 2000

Energy Technology Data Exchange (ETDEWEB)

Back, B. B [Argonne National Laboratory (United States)] (and others)

2001-12-01

The relativistic heavy ion collider (RHIC) at Brookhaven national laboratory delivered in June 2000 the first collisions between Au nuclei at the highest center-of-mass energies achieved in a controlled environment to date. PHOBOS is one of the four experiments installed during this phase of RHIC running. This paper will describe the PHOBOS experiment, and discuss the results of the first physics measurement, the pseudo rapidity densities of primary charged particles near mid rapidity in central Au+Au collisions at two different energies, S{sub N}N{sup .}5=56 and 130 GeV. The observed densities are higher than those previously observed in any collisions, and the rate of increase between the two energies is larger than that for nucleon-nucleon collisions at comparable beam energies. This talk will describe the PHOBOS experiment, discuss the first physics measurement, and conclude with the present status of the experiment, the physics analysis and the perspectives for the future. [Spanish] El elativistic heavy ion collider (RHIC) en Brookhaven national laboratory produjo por primera vez colisiones de nucleos de oro (Au) a las energias mas altas alcanzadas en un medio ambiente controlado. PHOBOS es uno de los cuatro experimentos presentes en DIC durante su fase inicial. Este articulo describe en detalle a PHOBOS y discute los primeros resultados publicados acerca de la fisica de DIC, esto es la densidad de particulas primarias a id rapidity en colisiones centrales de Au+Au a dos diferentes energias S{sub N}N{sup .}5 =56 y 130 GeV. Las densidades observadas son mas altas que en cualquier otra experimento anterior, las densidades obtenidas son tambien mas altas que las encontradas en colisiones proton-proton a energias comparables. Este articulo tambien discute el estado actual del experimento asi como los planes para el futuro.

Rearing of fat snook (“Centropomus parallelus” at different stocking densities Criação do robalo-peva ("Centropomus parallelus" submetido a diferentes densidades de estocagem

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Pedro Carlos da Silva Serralheiro

2007-10-01

Full Text Available Studies on the effect of stocking density on the growth of fat snook Centropomus parallelus were conducted in floating net cages in the north coast of the State of São Paulo, in Ubatuba City. Juveniles weighing 32.53 ± 6.54 g were stocked in densities of 20 and 40 fish/m3 and appraised for 160 days. Fish were fed commercial diet with 40% of crude protein, supplied twice a day, at the rate of 3% biomass of each tank-net. The environmental variables (water temperature, oxygen level, salinity and transparency were according to the parameters considered ideals for the species. Survival and the apparent feed conversion were not different (p <0.05 between the treatments. The mean final weights, specific growth rate and daily gain weight, indicated that the treatment of lower density was (p <0.05 superior to higher density. In relation to total weight gain, an accretion was observed of 98.6 and 87.9 g for the densities of 20 and 40 fishes/ m3, respectively. However, final biomass was superior (p<0.05 for the treatment with higher density, demonstrating a straight relationship between density and biomass production observed in the fish farming.Estudos sobre o efeito da densidade de estocagem na sobrevivência e no desempenho produtivo do robalo-peva Centropomus parallelus, criado em tanque-rede, foram realizados no litoral norte do Estado de São Paulo, em Ubatuba. Juvenis pesando 32,53 ± 6,54 g foram estocados em densidades de 20 e 40 peixes/m3 e avaliados durante 160 dias. Os peixes foram alimentados com ração comercial com 40% de proteína bruta, fornecida duas vezes ao dia, à taxa de 3% da biomassa de cada tanque-rede.. As variáveis ambientais (temperatura da água, teor de oxigênio, salinidade e transparência mantiveram-se dentro dos parâmetros considerados ideais para a espécie. Em relação à sobrevivência e a conversão alimentar aparente, não foram observadas diferenças significativas (p<0.05 entre os tratamentos. As médias de

Análisis de vulnerabilidad ambiental de la cuenca alta del río San Pedro, estado Miranda, Venezuela

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Haideé Coromoto Marín

2017-12-01

Full Text Available Se caracterizó la vulnerabilidad ambiental por inundación y desplazamiento en comunidades asentadas en la Cuenca alta del río San Pedro, municipio Guaicaipuro, estado Miranda; Venezuela usando SIG. El área de estudio se dividió en dos zonas, una ligeramente intervenida (A y otra fuertemente intervenida (B, para obtener los mapas temáticos usados como indicadores, los cuales se estandarizaron mediante la técnica de re-clasificación asignándoles valores numéricos en una escala del 1 al 5. Los resultados muestran que la vulnerabilidad por inundación en la subcuenca siguió la siguiente tendencia: clase media (3 33.75% > clase Baja (2 31.91% > clase muy Baja (1 26.86% > clase Alta (4 6.12% > clase muy alta (5 1.37%, no obstante las clases alta y muy alta se corresponde con comunidades cercanas al río, caracterizadas por la presencia de desarrollos urbanos, alta actividad agrícola, sugiriendo un alto riesgo por inundación. La distribución espacial de la vulnerabilidad por desplazamiento sugiere que predomina la clase media (3 y baja (2, las cuales representan el 50.58% y 36.25% respectivamente, mientras que el resto de las clase como alta (4, muy baja (1 y muy alta (5 mostraron porcentajes de 9.37, 3.29 y 0.41 respectivamente. Las clases de vulnerabilidad alta y muy alta están localizadas en el área de mayor intervención (Zona B, con un patrón muy irregular asociado a suelos con altas pendientes (>30% y manejo de suelo con cultivos pocos protectores como las hortalizas, favoreciendo procesos de degradación e incidiendo en la sustentabilidad de la zona. Los resultados obtenidos han servido para discriminar cuales comunidades son más vulnerables y establecer prioridades en cuanto a la intervención para minimizar los impactos ambientales.

Cambios en los precios de bebidas y alimentos con impuesto en áreas rurales y semirrurales de México

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M Arantxa Colchero

2017-03-01

Full Text Available Objetivo. Analizar cambios en precios asociados con la implementación de los impuestos a bebidas azucaradas y alimentos no básicos con alta densidad energética imple­mentados en 2014. Material y métodos. Se recolectaron precios en áreas rurales y semiurbanas en diciembre de 2013, y abril y diciembre de 2014. Se analizaron cambios en precios por tipo de bebidas y alimento con impuesto usando modelos de efectos fijos y estratificando por región, tipo de establecimiento y tamaño de presentación. Resultados. El impuesto a bebidas azucaradas no pasó por completo a los precios; en promedio, los precios aumentaron 0.73 pesos por litro. Para alimentos con alta densidad energética, el impuesto pasó igual o mayor al monto del impuesto para galletas, barras de cereal y cereales de caja. Conclusión. El potencial efecto de los impuestos en consumo podría ser menor al esperado en áreas rurales dado que los impuestos no pasaron por completo a los precios.

Recruitment of mud clam Polymesoda erosa (Solander, 1876) in a mangrove habitat of Chorao Island, Goa

Digital Repository Service at National Institute of Oceanography (India)

Clemente, S.; Ingole, B.S.

ocorrendo em setembro de 2004. A densidade de adultos fixados no lado terrestre variou de 7 a 12 indiv.m-2 (média: 9 ± 6 dp; n = 122). Na região voltada ao mar, os adultos estiveram ausentes no nível da maré baixa. As altas densidades de juvenis... observadas nos níveis de maré baixa e média estão provavelmente relacionadas à inundação frequente da área, o que permite aos indivíduos jovens alimentarem-se adequadamente e atingirem os tamanhos críticos em que a vulnerabilidade aos estresses físicos e...

Diseño de un sistema de carga y descarga de energía eléctrica para vehículos eléctricos de alto desempeño

OpenAIRE

Martínez Martínez, Wilmar Hernán

2013-01-01

Uno de los grandes inconvenientes de la movilidad eléctrica en Colombia es la baja densidad de potencia que presentan los vehículos autónomos. Esto se debe a que la mayoría de fabricantes diseñan sus vehículos para países con terrenos estables y de bajo relieve. Por esta razón, esta investigación muestra el diseño de los diferentes subsistemas eléctricos de un vehículo eléctrico de alto desempeño con alta densidad de potencia y cuya primera aplicación es correr un cuarto de milla en 10 segun...

COMPARAÇÃO ENTRE DOIS MÉTODOS DE AVALIAÇÃO DA VARIABILIDADE GENÉTICA EM VOLUME, DENSIDADE BÁSICA DA MADEIRA E MATÉRIA SECA DE Pinus tecunumanii (Schwd Eguiluz e Perry

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Fabio Bakker Isaias

2004-01-01

Full Text Available O volume, a densidade básica e o peso da matéria seca da madeira de oitenta e quatro árvores, de sete famílias de polinização aberta, procedência de Mountain Pine Ridge (MPR, Belize, de Pinus tecunumanii (Schwd Eguiluz e Perry foram estimados aos 12 e 17 anos de idade em experimento instalado em Planaltina, Distrito Federal. Para todos os parâmetros avaliados, houve diferenças significativas entre famílias, exceto para densidade básica, medidas aos 17 anos de idade. Aos 12 anos de idade, foram testados dois métodos de avaliação para densidade básica da madeira; um com os três melhores indivíduos da parcela, e outro com todos indivíduos da parcela. As médias de densidade foram de 0,425 g/cm3 e 0,424 g/cm3, praticamente iguais para as duas amostragens. A correlação da densidade básica entre as idades foi positiva e significativa, mostrando um ganho de 0,031 g/cm3 em 5 anos. A herdabilidade da densidade básica calculada aos 12 anos de idade, em nível individual, para família e dentro de família, considerando-se a amostragem com três e seis indivíduos, foi de respectivamente 0,43, 0,81, 0,33 e 0,47, 0,63, 0,37. Como conclusão, as seleções para densidade básica devem ser feitas preferencialmente em idades quando a competição entre os indivíduos ainda não atingiu níveis elevados. Ganhos consideráveis podem ser obtidos na seleção de indivíduos ou famílias dentro da população de MPR, Belize, na região do Cerrado. Será necessário trabalhar com populações de maior base genética.

Densidade de estocagem e salinidade da água na larvicultura do pacamã Stocking density and water salinity on pacamã larviculture

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Ronald Kennedy Luz

2008-07-01

Full Text Available O objetivo deste trabalho foi avaliar o efeito da densidade de estocagem e da salinidade da água, na larvicultura do pacamã Lophiosilurus alexandri, alimentado com náuplios de Artemia sp. Foram utilizadas três densidades de estocagem: 20, 40 e 60 larvas L-1 (D20, D40 e D60, respectivamente. Para cada densidade testaram-se três índices de salinidade da água: água doce (S0, 2‰ (S2 e 4‰ (S4, em delineamento experimental inteiramente ao acaso, em esquema fatorial 3x3, com três repetições. Foram analisados: crescimento, sobrevivência, mortalidade, canibalismo, produtividade e níveis de amônia não ionizada. As concentrações de amônia não ionizada foram maiores nas densidades D40 e D60. Aos dez dias de alimentação, o peso foi afetado negativamente em D40 e D60 associado à maior salinidade da água (S4. A maior sobrevivência foi obtida no tratamento D20S2, enquanto os menores valores foram registrados em relação à salinidade S4, independentemente da densidade testada. Foram verificadas baixas taxas de mortalidade e ausência de canibalismo. A produção de juvenis também foi influenciada pelos fatores avaliados. Larvas de L. alexandri podem ser criadas, durante os dez primeiros dias de alimentação exógena, em água doce ou a 2‰ com maior produção de juvenis na densidade D60.The objective of this work was to evaluate the effect of stocking density and water salinity levels on Lophiosilurus alexandri (pacamã larvae rearing fed with Artemia sp. nauplii. Three stocking densities were used: 20, 40 and 60 larvae L-1 (D20, D40 and D60, respectively. For each density, three different levels of salinity were tested: freshwater (S0, 2‰ (S2 and 4‰ (S4, in a completely randomized design, in a 3x3 factorial scheme, with three replications. The growth, survival, mortality, cannibalism, production and nonionized ammonia levels were evaluated. The nonionized ammonia levels were higher at D40 and D60. At 10 days of feeding, the

Influence of fiber length on flexural and impact properties of Zalacca Midrib fiber/HDPE by compression molding

Science.gov (United States)

Pamungkas, Agil Fitri; Ariawan, Dody; Surojo, Eko; Triyono, Joko

2018-02-01

The aim of the research is to investigate the effect of fiber length on the flexural and impact properties of the composite of Zalacca Midrib Fiber (ZMF)/HDPE. The process of making composite was using compression molding method. The variation of fiber length were 1 mm, 3 mm, 5 mm, 7 mm and 9 mm, at 30% fiber volume fraction. The flexural and impact test according to ASTM D790 and ASTM D5941, respectively. Observing fracture surface was examained by using Scanning Electron Microscopy (SEM). The results showed that the flexural and impact strengths would be increase with the increase of fiber length.

Época e densidade de semeadura afetando a produção de Capim Piatã e Brachiaria ruziziensis em consórcio com soja

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Eduardo Andrea Lemus Erasmo

2017-09-01

Full Text Available O sistema de consórcio entre culturas é usado em muitas partes do mundo, em geral, tem se mostrado mais produtivo que o monocultivo. Assim sendo, o presente trabalho tem como objetivo avaliar a densidade e época de semeadura de Brachiária brizantha cv. BRS Piatã e Brachiaria ruziziensis em consorcio com a cultura da soja. O estudo foi conduzido em condições de campo na estação experimental da Universidade Federal do Tocantins. O delineamento experimental utilizado foi em blocos casualizados, em esquema fatorial de (2 x 2 x 3 + 4, com quatro repetições, correspondendo a duas épocas de semeadura da Brachiaria brizantha cv. BRS Piatã e Brachiaria ruziziensis, duas densidades de semeadura da braquiária e a braquiária crescida isoladamente nas duas densidades e épocas testadas. 140 dias após o plantio da soja foram determinados o número de perfilhos, altura, massa seca da parte aérea; massa seca foliar e massa seca do colmo. Os dados foram submetidos à análise variância e as médias comparadas pelo teste Tukey. O cultivo da braquiária em consórcio com a soja promoveu a redução de todos os parâmetros avaliados. O aumento da densidade de semeadura promoveu redução no perfilhamento, e aumento na produção de matéria seca.

DILEMA ECONÓMICO - AMBIENTAL DEL URBANISMO EN CIUDADES LATINOAMERICANAS

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Néstor Garza

2009-01-01

Full Text Available En este artículo se plantea que la intervención sobre el funcionamiento de los mercados de suelo ha coincidido en Estados Unidos con el fenómeno de la suburbanización y una gama amplia de problemáticas ambientales asociadas a ésta. De otra parte, se argumenta que en América Latina no se ha seguido ese tipo de políticas, y se ha privilegiado intervenciones que han implicado ciudades compactas y de rentas altas, con problemas ambientales y urbanos por la escasa provisión de bienes públicos que viabilicen altas densidades. Se describe el proceso que dio lugar al ejercicio del urbanismo en el Primer Mundo y posteriormente en América Latina, y se detectan faltantes importantes en la conceptualización del fenómeno de la urbanización para el caso de esta última región. El artículo concluye que es inevitable confrontar un dilema económico-ambiental en el ejercicio del urbanismo, el cual se resume de la siguiente manera: la gestión activa de suelo implica precios bajos y suburbanización, con consecuencias no deseables, mientras que su ausencia implica precios altos con altas densidades que requieren costosas infraestructuras de soporte.

Development of a high density fuel based on uranium-molybdenum alloys with high compatibility in high temperatures

OpenAIRE

OLIVEIRA, FABIO B.V. de

2014-01-01

Este trabalho tem como objetivo o desenvolvimento de um combustível nuclear de alta densidade e baixo enriquecimento com base na liga ?-UMo, para aplicações nas quais seja necessário desempenho satisfatório a altas temperaturas, considerando-se a sua utilização na forma de dispersão. Para tanto, partiu-se da análise dos resultados dos testes RERTR (sigla em inglês para \\"Reduced Enrichment of Research and Test Reactors\\") e de alguns trabalhos teóricos envolvendo a elaboração de ligas metaest...

Anatomía y densidad o peso específico de la madera

OpenAIRE

León Hernández, Williams J.

2010-01-01

El presente trabajo trata sobre la relación que existe entre las características anatómicas de la madera y su densidad o peso específico. Tomando en consideración la importancia de esta propiedad física y su relación con otras propiedades físico-mecánicas de la madera, es necesario conocer cuáles son los elementos celulares que influyen sobre la misma. En el caso de maderas de coníferas, las características de las traqueidas definen el valor promedio y el patrón de variac...

Optimization of Injection Molding Parameters for HDPE/TiO2 Nanocomposites Fabrication with Multiple Performance Characteristics Using the Taguchi Method and Grey Relational Analysis

Directory of Open Access Journals (Sweden)

Hifsa Pervez

2016-08-01

Full Text Available The current study presents an investigation on the optimization of injection molding parameters of HDPE/TiO2 nanocomposites using grey relational analysis with the Taguchi method. Four control factors, including filler concentration (i.e., TiO2, barrel temperature, residence time and holding time, were chosen at three different levels of each. Mechanical properties, such as yield strength, Young’s modulus and elongation, were selected as the performance targets. Nine experimental runs were carried out based on the Taguchi L9 orthogonal array, and the data were processed according to the grey relational steps. The optimal process parameters were found based on the average responses of the grey relational grades, and the ideal operating conditions were found to be a filler concentration of 5 wt % TiO2, a barrel temperature of 225 °C, a residence time of 30 min and a holding time of 20 s. Moreover, analysis of variance (ANOVA has also been applied to identify the most significant factor, and the percentage of TiO2 nanoparticles was found to have the most significant effect on the properties of the HDPE/TiO2 nanocomposites fabricated through the injection molding process.

Optimization of Injection Molding Parameters for HDPE/TiO2 Nanocomposites Fabrication with Multiple Performance Characteristics Using the Taguchi Method and Grey Relational Analysis

Science.gov (United States)

Pervez, Hifsa; Mozumder, Mohammad S.; Mourad, Abdel-Hamid I.

2016-01-01

The current study presents an investigation on the optimization of injection molding parameters of HDPE/TiO2 nanocomposites using grey relational analysis with the Taguchi method. Four control factors, including filler concentration (i.e., TiO2), barrel temperature, residence time and holding time, were chosen at three different levels of each. Mechanical properties, such as yield strength, Young’s modulus and elongation, were selected as the performance targets. Nine experimental runs were carried out based on the Taguchi L9 orthogonal array, and the data were processed according to the grey relational steps. The optimal process parameters were found based on the average responses of the grey relational grades, and the ideal operating conditions were found to be a filler concentration of 5 wt % TiO2, a barrel temperature of 225 °C, a residence time of 30 min and a holding time of 20 s. Moreover, analysis of variance (ANOVA) has also been applied to identify the most significant factor, and the percentage of TiO2 nanoparticles was found to have the most significant effect on the properties of the HDPE/TiO2 nanocomposites fabricated through the injection molding process. PMID:28773830

USO DA INTERNET: DIFERENÇAS ENTRE CLASSE MÉDIA E ALTA

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Jorge Ferreira da Silva

2013-12-01

Full Text Available Este estudo busca propor e testar um modelo que explique o uso da internet pelos jovens e identificar possíveis diferenças neste uso entre jovens de classe média e alta. A motivação para a pesquisa partiu da observação dos novos hábitos de consumo originados do uso da internet por estes jovens, que consideram a tecnologia indispensável em suas vidas. Baseado na literatura, o modelo final envolveu os seguintes fatores: Barreiras Percebidas ao Acesso, Comunicação, Interatividade e Uso da Internet. As hipóteses de pesquisa foram testadas por meio de uma survey com 394 jovens, com a amostra sendo divida em dois grupos: jovens de classe média e jovens de classe alta. Os dados foram analisados por modelagem de equações estruturais multigrupo. Os resultados sugerem diferenças na utilização de internet entre jovens de classe média e alta, com somente a classe média sendo influenciada significativamente pela Interatividade e Comunicação percebidas.

Hormigones de alta resistencia con nano-adiciones y fibras de acero

OpenAIRE

Alizo Mirabal, Manuel Arturo

2015-01-01

El presente Trabajo Fin de Máster consistió en determinar la influencia que pueden poseer las nano-adiciones de Sílice y Alúmina y fibras de acero en un Hormigón de Alta Resistencia. Partiendo de una dosificación de Hormigón de Alta Resistencia conocida, que contenía humo de Sílice (10%) y fibras de poliolefina (3kg/m3), se les procedió a sustituir por la incorporación de nano-adiciones de Sílice y Alúmina (7% y 3% respectivamente) y añadiendo fibras de acero en lugar de poliolefina. En el pr...

Prediction of mechanical properties of composites of HDPE/HA/EAA.

Science.gov (United States)

Albano, C; Perera, R; Cataño, L; Karam, A; González, G

2011-04-01

In this investigation, the behavior of the mechanical properties of composites of high-density polyethylene/hydroxyapatite (HDPE/HA) with and without ethylene-acrylic acid copolymer (EAA) as possible compatibilizer, was studied. Different mathematical models were used to predict their Young's modulus, tensile strength and elongation at break. A comparison with the experimental results shows that the theoretical models of Guth and Kerner modified can be used to predict the Young's modulus. On the other hand, the values obtained by the Verbeek model do not show a good agreement with the experimental data, since different factors that influence the mechanical properties are considered in this model such as: aspect ratio of the reinforcement, interfacial adhesion, porosity and binder content. TEM analysis confirms the discrepancies obtained between the experimental Young's modulus values and those predicted by the Verbeek model. The values of "P", "a" and "σ(A)" suggest that an interaction among the carboxylic groups of the copolymer and the hydroxyl groups of hydroxyapatite might be present. In composites with 20 and 30 wt% of filler, this interaction does not improve the Young's modulus values, since the deviations of the Verbeek model are significant. Copyright © 2010 Elsevier Ltd. All rights reserved.

Influence of the nanotube oxidation on the rheological and electrical properties of CNT/HDPE composites

Energy Technology Data Exchange (ETDEWEB)

Nobile, Maria Rossella, E-mail: mrnobile@unisa.it; Somma, Elvira; Valentino, Olga; Neitzert, Heinz-Christoph [Department of Industrial Engineering – DIIn - Università di Salerno Via Giovanni Paolo II, 132 - 84084 Fisciano (Italy); Simon, George [Department of Materials Engineering, Monash University, Clayton, Victoria 3800 (Australia)

2016-05-18

Rheological and electrical properties of nanocomposites based on multi-walled carbon nanotubes (MWNTs) and high density polyethylene (HDPE), prepared by melt mixing in a micro-twin screw extruder, have been investigated. The effect of MWNT concentration (0.5 and 2.5 wt %) and nanotube surface treatment (oxidative treatment in a tubular furnace at 500°C for 1 hr in a 95% nitrogen, 5% oxygen atmosphere) has been analyzed. It has been found that the sample conductivity with oxidation of the nanotubes decreases more than 2 orders of magnitude. Scanning electron microscopy showed good adhesion and dispersion of nanotubes in the matrix, independently of the surface treatment. Electrical and rheological measurements revealed that the oxidative treatment, causing some reduction of the MWNT quality, decreases the efficiency of the nanotube matrix interaction.

Controlling Short-Range Interactions by Tuning Surface Chemistry in HDPE/Graphene Nanoribbon Nanocomposites.

Science.gov (United States)

Sadeghi, Soheil; Zehtab Yazdi, Alireza; Sundararaj, Uttandaraman

2015-09-03

Unique dispersion states of nanoparticles in polymeric matrices have the potential to create composites with enhanced mechanical, thermal, and electrical properties. The present work aims to determine the state of dispersion from the melt-state rheological behavior of nanocomposites based on carbon nanotube and graphene nanoribbon (GNR) nanomaterials. GNRs were synthesized from nitrogen-doped carbon nanotubes via a chemical route using potassium permanganate and some second acids. High-density polyethylene (HDPE)/GNR nanocomposite samples were then prepared through a solution mixing procedure. Different nanocomposite dispersion states were achieved using different GNR synthesis methods providing different surface chemistry, interparticle interactions, and internal compartments. Prolonged relaxation of flow induced molecular orientation was observed due to the presence of both carbon nanotubes and GNRs. Based on the results of this work, due to relatively weak interactions between the polymer and the nanofillers, it is expected that short-range interactions between nanofillers play the key role in the final dispersion state.

Evaluation of mechanical properties and durability performance of HDPE-wood composites

Energy Technology Data Exchange (ETDEWEB)

Tazi, M.; Erchiqui, F. [Engineering department, Université de Quebec en Abitibi-Témiscamingue (Canada); Kaddami, H. [Université Caddi Ayad Marrakech, Laboratoire ’LCO2MC’, B.P. 549, Marrakech 40000, Maroc (Morocco); Bouazara, M. [Mechanical department, Université de Québec à Chicoutimi Canada (Canada); Poaty, B. [Technology Center of industrial residuals, QC Canada (Canada)

2015-05-22

The objective of this work is to evaluate the mechanical properties and durability performance of bio-composite materials made from sawdust and thermoplastic polymer (HDPE). For the preparation of the composites, sawdust in different proportions with Maleic Anhydride grafted Polyethylene (MAPE) as the coupling agent was used. The thermal and mechanical properties were successively characterized. The results indicate that adding wood fillers to a polymer matrix increases the degree of crystallinity and improves the tensile strength and ductility of composites. On the contrary, resistance to water absorption decreases as a function of the wood fillers. Scanning electron microscopy (SEM) was used to analyze morphological structure alteration when exposed to intense weathering. The biodegradability of bio-composites up to 97 days was also investigated; the results indicate that, by increasing the filler content, the amount of weight loss increased as well. In other words, even though the addition of sawdust to thermoplastic polymer improves the mechanical performance of a composite material, it also accelerates the biodegradation rate of the composite. An optimum amount of filler content might compromise the effect of biodegradation and mechanical properties of composite materials.

Evaluation of mechanical properties and durability performance of HDPE-wood composites

International Nuclear Information System (INIS)

Tazi, M.; Erchiqui, F.; Kaddami, H.; Bouazara, M.; Poaty, B.

2015-01-01

The objective of this work is to evaluate the mechanical properties and durability performance of bio-composite materials made from sawdust and thermoplastic polymer (HDPE). For the preparation of the composites, sawdust in different proportions with Maleic Anhydride grafted Polyethylene (MAPE) as the coupling agent was used. The thermal and mechanical properties were successively characterized. The results indicate that adding wood fillers to a polymer matrix increases the degree of crystallinity and improves the tensile strength and ductility of composites. On the contrary, resistance to water absorption decreases as a function of the wood fillers. Scanning electron microscopy (SEM) was used to analyze morphological structure alteration when exposed to intense weathering. The biodegradability of bio-composites up to 97 days was also investigated; the results indicate that, by increasing the filler content, the amount of weight loss increased as well. In other words, even though the addition of sawdust to thermoplastic polymer improves the mechanical performance of a composite material, it also accelerates the biodegradation rate of the composite. An optimum amount of filler content might compromise the effect of biodegradation and mechanical properties of composite materials

Processamento radiográfico - câmara escura portátil: relação entre filtro de luz e densidade de base + véu

Directory of Open Access Journals (Sweden)

TAMBURÚS José Roberto

1999-01-01

Full Text Available O objetivo desta pesquisa foi avaliar o efeito sobre a densidade de base + véu de filmes radiográficos, decorrente do uso da luz filtrada pelo polímero acrílico utilizado nas câmaras portáteis para processamento radiográfico. Filmes Kodak Ultra-speed e Ektaspeed Plus foram colocados no interior de uma câmara desse tipo e submetidos durante cinco minutos às condições de iluminação natural e artificial em que elas são rotineiramente utilizadas. Depois disso, os filmes foram processados pelo método temperatura-tempo em câmara escura convencional, juntamente com filmes dos mesmos grupos de sensibilidade que serviram como controle. Os valores densitométricos obtidos das amostras dos filmes foram analisados pelo teste de Mann-Whitney que indicou ao nível de 1% de significância, que os filmes submetidos às condições da câmara portátil apresentaram densidades de base + véu maiores em relação aos grupos controle. Os resultados mostraram que o filme Ektaspeed Plus apresentou valores maiores de densidade de base + véu em comparação com o filme Ultra-speed e que, embora o acrílico filtre a luz de forma similar ao filtro Kodak GBX 2, a maior intensidade de luz no interior da câmara escura portátil ocasionou o aumento na densidade de base + véu.

Características agronómicas de la soya en función de las densidades de siembra y profundidad de deposición de abono

Directory of Open Access Journals (Sweden)

Jorge Wilson Cortez

2011-02-01

Full Text Available El objetivo de este trabajo fue evaluar las características agronómicas de la soya sembrada en Sistema de Siembra Directa, en función de las densidades de siembra (15, 16 y 20 plantas por metro y la profundidad de deposición de abono (11, 14 y 17 cm. El experimento fue realizado en el Departamento de Ingeniería Rural, UNESP/Jaboticabal, utilizando, en el delineamiento, parcelas subdivididas en bloques al acaso, con cuatro repeticiones. Características agronómicas de la soya analizadas: número de días de aparición, índice de aparición, porcentaje de daños, altura de plantas, altura de inserción de la primera vaina, vainas por planta, granos por vaina, porcentaje de plantas sobrevivientes y productividad. Los resultados indicaron que el número de días de aparición, índice de aparición y el porcentaje de daños, no fueron influenciados por las densidades y la profundidad de deposición de abono. Los daños por insectos y aves fueron del orden de 30% de plantas atacadas. La altura de plantas, altura de inserción de la primera vaina, vainas por planta y granos por vaina no variaron en relación a la densidad y profundidad de deposición de abono. La productividad de la soya (5.146 kg ha-1 fue semejante en las densidades y profundidades de deposición de abono.

Produção e qualidade de rosas em três densidades de plantio e uso de soluções conservantes com sacarose na colheita de rosas

OpenAIRE

Bastos, Fernanda Espíndola Assumpção

2014-01-01

O objetivo deste trabalho foi avaliar a produtividade das cultivares de rosa Avalanche‟ e Carola‟, de coloração branca e vermelha, respectivamente, em três densidades de plantio bem como a qualidade e conservação pós-colheita da cultivar Carola‟, no município de Lages-SC. O experimento referente à densidade de plantio foi implantado em janeiro de 2013, no campus da Universidade do Estado de Santa Catarina (UDESC), com espaçamento de 1,0 m entre fileiras e de 30, 40 e 50 c...

Analytical protocol to study the food safety of (multiple-)recycled high-density polyethylene (HDPE) and polypropylene (PP) crates: Influence of recycling on the migration and formation of degradation products

NARCIS (Netherlands)

Coulier, L.; Orbons, H.G.M.; Rijk, R.

2007-01-01

An analytical protocol was set up and successfully applied to study the food safety of recycled HDPE and PP crates. A worst-case scenario was applied that focused not only on overall migration and specific migration of accepted starting materials but also on migratable degradation products of

Efectos del alta hospitalaria temprana en el periodo posparto en la Clínica del Prado, Medellín, Colombia

OpenAIRE

Cardona-Ospina, Arturo; Ordoñez-Molina, Jaime; Vásquez-Trespalacios, Elsa María; Universidad CES; Mestra-Palomino, Laureano; García-Posada, Raúl Alejandro

2014-01-01

Problema: evaluar el efecto del alta hospitalaria temprana en pacientes sanas. Objetivo: establecerel riesgo de complicaciones en pacientes obstétricas con alta temprana respecto a aquellasque egresan después de 24 horas. Métodos: cohorte prospectiva con seguimiento postparto.Resultados: 750 pacientes, edad promedio de 24,5 años y edad gestacional de 38,5 semanas.El porcentaje de consulta luego del alta fue 2,0 %. El efecto del alta hospitalaria tempranasobre la necesidad de consultar luego d...

Relação das propriedades mecânicas e densidade de postes de madeira de eucalipto com seu estado de deterioração

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Rafael Colombo Abruzzi

2012-12-01

Full Text Available Este trabalho apresenta correlações obtidas entre propriedades mecânicas, densidade e o estado de deterioração de postes de eucalipto novos e retirados de serviço. O estado de deterioração foi determinado por inspeções em campo de postes da rede de distribuição de energia elétrica no sul do Brasil. Postes em diferentes estados de deterioração foram retirados da rede para os ensaios de flexão estática e medidas de densidade. Os testes mecânicos indicaram que os valores médios da resistência a flexão e da rigidez decrescem com o estado de deterioração do eucalipto. Entretanto, verificou-se uma grande variação nessas medidas com diferentes classes de deterioração apresentando resistência mecânica residual similar. Esse comportamento pode ser explicado pela influência da densidade da madeira nas correlações entre propriedades mecânicas e o estado de deterioração dos postes. Madeiras menos densas podem apresentar baixa resistência mecânica residual mesmo sem apresentar sinais de deterioração. O estudo da caracterização da madeira de eucalipto indicou que o estado de deterioração avaliado pela inspeção em campo, por si só não é um bom indicativo para prever a durabilidade das estruturas de madeiras, fazendo-se necessária uma análise preliminar da densidade da mesma.

Hemorragia digestiva alta no varicosa: comportamiento e índice de Rockall

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John Karol Ramírez

Full Text Available Introducción: la hemorragia digestiva alta no varicosa es actualmente una emergencia quirúrgica de difícil manejo, hecho que motivó el conocer su comportamiento y, usando el índice de Rockall, el riesgo de los afectados de sufrir resultados adversos durante su evolución, aquellos de posible alta precoz y las causas que la impiden. Métodos: estudio descriptivo de corte transversal realizado en el Hospital General Docente "Ernesto Guevara de la Serna" con 182 pacientes atendidos entre 2009 y 2010. Resultados: los hombres fueron los más afectados (54,4 % y el grupo de 60-80 años tuvo el mayor número de casos. La úlcera gastroduodenal fue la primera causa (52,7 %. La melena se presentó como manifestación inicial en el 60,4 % de los pacientes. La hipertensión arterial fue la comorbilidad más frecuente (60,7 %. El 44,5 % de los pacientes necesitó transfusión sanguínea. La mortalidad fue del 8,2 %. La mayor parte de la muestra se ubicó en el grupo de riesgo intermedio de Rockall (40,1 %. Recibió alta precoz solo el 11,5 % de los pacientes, y la inestabilidad hemodinámica (38 % fue la mayor responsable de este bajo número. El Rockall tuvo sensibilidad del 98,3 %, especificidad del 56,9 %, valor predictivo positivo del 52,3 %, valor predictivo negativo del 98,6 % y una exactitud del 70,9 %. En los pacientes clasificados de bajo riesgo la única complicación fue la recidiva (1,4 %. Conclusiones: el alta precoz puede ser dada a pacientes con Rockall bajo, siempre que se preste especial atención a la estabilidad hemodinámica.

Procesos de automatización cognitiva en alumnado con altas capacidades intelectuales

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Juan Montero-Linares

2013-05-01

Full Text Available Proponemos desde el enfoque del procesamiento de la información, el estudio de características cognitivas que faciliten la identificación de las altas capacidades. A tal fin, elaboramos una tarea de habilidad de segmentación silábica que, a partir del modelo propuesto por Baddeley sobre la memoria de trabajo y la distinción entre procesos automáticos y controlados, nos permitiese comprobar las diferencias en cuanto a la capacidad de automatización de la información y si los indicadores propuestos en la misma, tenían suficiente poder clasificatorio o predictivo en la identificación de la alta capacidad intelectual. Participaron 480 niños y niñas de primero a cuarto de Educación Primaria. Se clasificaron, en función de su CI, en dos grupos: alumnado de altas capacidades y alumnado de capacidades medias. Se les administró una batería de pruebas entre las que se encontraba el test de habilidad de segmentación silábica, lo que permitió realizar su estandarización. Los resultados mostraron que los alumnos con CI superior a 130 fueron capaces de automatizar la segmentación de forma más eficiente que los de inteligencia media. La medición de los procesos automáticos a través del test de habilidad de segmentación silábica, permitió diferenciar a los participantes de altas capacidades de los que no lo eran.

"Estudo comaparativo das densidades radiográficas de diferentes filmes periapicais obtidas por meio da análise computadorizada em valores de alumínio-equivalente"

OpenAIRE

Felipe Paes Varoli

2004-01-01

RESUMO O objetivo deste estudo foi obter as densidades radiográficas de diferentes filmes periapicais por meio de um programa computadorizado que utiliza a imagem equivalente em alumínio (alumínio-equivalente). Avaliaram-se os filmes Agfa Dentus M2 “Comfort”, Kodak InSight, Kodak Ektaspeed Plus, Kodak Ultra-speed e Kodak D. Todos foram expostos aos raios X juntamente com um escalímetro de Alumínio, variando-se o tempo de exposição (0,1 a 1 segundo). Após a leitura das densidades radiográfica...

Estudio del perfil lipídico canino por edad y sexo

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José Henry Osorio

2012-06-01

Full Text Available Este trabajo se propone comparar el perfil lipídico en caninos criollos o sus cruces en el departamento de Caldas, Colombia, y analizar la correlación entre las cantidades lipídicas del suero de seis grupos. Se obtuvieron muestras de sangre de 156 caninos en estado de ayuno, diferenciados por sexo y edad (32 machos y 34 hembras menores de un año, y 42 machos adultos y 48 hembras mayores de un año; se determinaron triglicéridos, colesterol total y el colesterol de las lipoproteínas de alta densidad mediante el método enzimático colorimétrico. El colesterol de las lipoproteínas de muy baja densidad y de baja densidad se determinó usando las fórmulas de Friedewald. Las medias ± desviación estándar para colesterol total, triglicéridos y colesterol de las lipoproteínas de alta, muy baja y baja densidad en mg/dL fueron de: 214,91 ± 75,3; 50,01 ± 42,5; 133,73 ± 40,11; 10, 00 ± 8,51; 71,17 ± 57,12 respectivamente. Para el resto de los grupos, los triglicéridos, el colesterol VLDL y el colesterol LDL no fueron significativos (p ≥ 0,05. El colesterol HDL en los caninos jóvenes y adultos presentó un valor de 0,0377 en el valor p del test F, que mostró diferencia significativa (p < 0,05. En los resultados mostrados por los caninos jóvenes, especialmente los machos, se observa que estos presentan un colesterol total y un colesterol HDL más altos si se compara con los adultos.

Altas tecnologías, conflictos armados y seguridad humana

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Elena del Mar García Rico

2016-01-01

Full Text Available El examen de las amenazas para la seguridad y el bienestar de las personas inherentes al concepto de seguridad humana exige ocuparse también de las consecuencias que la utilización de las altas tecnologías puedan ocasionar en relación con los conflictos armados actuales. De ahí que en este trabajo abordemos los cambios relevantes en la naturaleza y características de los nuevos conflictos armados provocados por la celeridad y amplitud en el empleo de altas tecnologías y su desigual distribución entre los beligerantes, tal y como muestran las llamadas guerras de coste cero, de cuarta generación o asimétricas, e incluso las híbridas. Asimismo, el desarrollo reciente de las capacidades militares cibernéticas, de los sistemas de armas autónomos y de los vehículos aéreos no tripulados plantea nuevos retos al Derecho Internacional Humanitario, aspectos contemplados en este estudio.

Determinantes sociodemográficos, antropométricos e alimentares de dislipidemia em pré-escolares

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Luciana N. Nobre

2013-10-01

Full Text Available OBJETIVO: O objetivo deste estudo foi investigar os determinantes de dislipidemia em pré-escolares. MÉTODOS: A partir de um desenho transversal, foi avaliado um total de 227 pré-escolares com 5 anos de idade residentes em uma área urbana da cidade de Diamantina, Minas Gerais, Brasil. Foram avaliados: variáveis bioquímicas, antropométricas, condição socioeconômica e comportamental, a partir de um questinário; e ingestão alimentar, a partir de um questionário de fequência de consumo de alimentos. Os padrões alimentares denominados "dieta mista", "fast food" e "não saudável" foram identificados por meio de análise de componentes principais. Os determinantes de dislipidemia foram examinados através da análise de regressão de Poisson. RESULTADOS: A prevalência de dislipidemia, neste estudo, foi de 65,19%. Os pré-escolares que consumiam com menos frequência alimentos do padrão "dieta mista" tiveram um risco maior de concentrações mais altas de lipoproteína de baixa densidade (PR = 2,30; p = 0,004, em comparação com aqueles com um consumo mais frequente do padrão "dieta mista". Os pré-escolares cujas mães apresentaram uma escolaridade mais baixa tiveram menor risco de concentrações mais altas de lipoproteína de baixa densidade (PR = 0,43; p = 0,003, e os pré-escolares que estavam com sobrepeso/obesos apresentaram maior risco de concentrações mais altas de lipoproteína de baixa densidade (PR = 2,23; p = 0,003. CONCLUSÃO: Os determinantes de dislipidemia identificados neste estudo foram o consumo menos frequente de alimentos do padrão "dieta mista", índice de massa corporal mais alto e um maior nível de escolaridade materna. Este estudo mostra que, apesar da baixa idade do grupo em estudo, já estão apresentando alta prevalência de dislipidemia, que é um fator de risco importante para doença cardiovascular.

Catalytic co-pyrolysis of paper biomass and plastic mixtures (HDPE (high density polyethylene), PP (polypropylene) and PET (polyethylene terephthalate)) and product analysis

International Nuclear Information System (INIS)

Chattopadhyay, Jayeeta; Pathak, T.S.; Srivastava, R.; Singh, A.C.

2016-01-01

Catalytic co-pyrolysis of biomass and plastics (HDPE (high density polyethylene), PP (polypropylene) and PET (polyethylene terephthalate)) has been performed in a fixed-bed reactor in presence of cobalt based alumina, ceria and ceria-alumina catalysts to analyze the product distribution and selectivity. Catalysts are synthesized using co-precipitation method and characterized by BET (Brunauer–Emmett–Teller) surface area and XRD analysis. The effect of catalytic co-pyrolysis at different temperature with product distribution has been evaluated. The results have clearly shown the synergistic effect between biomass and plastics, the liquid products gradually increases forming with rise in the plastic content in the blend. Gaseous products have yielded most during pyrolysis of blend having biomass/plastics ratio of 5:1 with the presence of 40% Co/30% CeO_2/30% Al_2O_3 catalyst with hydrogen gas production touched its peak of 47 vol%. Catalytic performance enhanced with increase with the cobalt loading, with best performance attributing to 40% Co/30% CeO_2/30% Al_2O_3 catalyst. - Highlights: • Catalytic co-pyrolysis of biomass and plastics (HDPE, PP & PET) blends in fixed-bed reactor. • Strong synergistic effect evident between biomass and plastics. • Solid residue diminished with application of catalysts. • Aromatics and olefins production increases with higher plastic content. • More hydrogen production with application of catalysts with higher cobalt content.

Época e Densidade de Semeadura de Aveia Preta (Avena strigosa Schreb. e Azevém (Lolium multiflorum Lam. no Alto Vale do Itajaí, Santa Catarina

Directory of Open Access Journals (Sweden)

Flaresso Jefferson Araújo

2001-01-01

Full Text Available O experimento foi conduzido na Epagri, Estação Experimental de Ituporanga, SC, com o objetivo de determinar a época e a densidade de semeadura de Avena strigosa Schreb. (aveia preta e Lolium multiflorum Lam. (azevém. Os tratamentos foram avaliados por três anos, dispostos num delineamento de blocos casualizados, em parcelas subdivididas com três repetições. As épocas de semeadura para as duas espécies foram: Época 1 - meados de março; Época 2 - meados de abril; Época 3 - meados de maio; Época 4 - meados de junho. As densidades de sementes puras viáveis foram: aveia preta, 60, 80 e 100 kg/ha; azevém, 15, 25 e 35 kg/ha. A aveia preta foi menos produtiva e mais precoce que o azevém. Para as duas espécies, não houve diferença significativa entre as densidades de semeaduras. A melhor época de implantação das espécies foi em meados de abril.

Densidade populacional de raposa-do-campo Lycalopex vetulus (Carnivora, Canidae em áreas de pastagem e campo sujo, Campinápolis, Mato Grosso, Brasil

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Ednaldo C. Rocha

2008-03-01

Full Text Available Diante da crescente descaracterização do Bioma Cerrado em função da expansão da fronteira agropecuária na região central do Brasil, torna-se importante avaliar a capacidade de adaptação das espécies ao ambiente antropizado. Neste sentido, este trabalho foi desenvolvido com o objetivo de estimar e comparar a densidade populacional da raposa-do-campo Lycalopex vetulus (Lund, 1842 em duas áreas com diferentes graus de alteração, pastagem e campo sujo, em Campinápolis, Mato Grosso. Para tanto, no período entre agosto a novembro de 2005, foram efetuados censos noturnos ao longo de transectos lineares, totalizando percursos de 129,8 km na área de campo sujo e 62,08 km na área de pastagem. Estimativas de densidade populacional foram geradas utilizando o programa Distance 5.0, sendo que o modelo e ajuste mais adequados aos dados foram half-normal + hermite. Foram obtidas 23 e 52 detecções de raposas-do-campo nas áreas de campo sujo e pastagem, respectivamente. A densidade populacional de raposa-do-campo na área de pastagem (D=4,28 indivíduos/km²; IC=2,69 - 6,82 foi maior que na área de campo sujo (D=1,21 indivíduos/km²; IC=0,73 - 2,01, fato que deve estar relacionado, principalmente, com a disponibilidade de alimento e redução de potenciais predadores. Por apresentar uma dieta composta principalmente de cupins, especialmente os dos gêneros Syntermes e Cornitermes, a raposa-do-campo encontra na área de pastagem uma base alimentar abundante e estável. Além disto, a simplificação ambiental, em função da implantação de pastagens acaba por reduzir, ou até mesmo eliminar, animais que são potenciais predadores de raposas-do-campo, como Chrysocyon brachyurus (Illiger, 1815, favorecendo o aumento da densidade populacional da espécie neste tipo de ambiente. Por fim, características adaptativas apresentadas pela raposa-do-campo têm permitido que esta espécie sobreviva, inclusive apresentando elevada densidade

Nanocompósitos de PEAD/PEBDL: avaliação da esfoliação da argila organofílica pela aplicação do modelo de Nielsen e das propriedades mecânicas, ópticas e permeabilidade PEAD/PEBDL composites: evaluation of the exfoliation of organophilic clay using the Nielsen model and of the mechanical, optical and permeability properties

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Ana R. Morales

2010-01-01

Full Text Available Uma blenda de polietileno de alta densidade e polietileno de baixa densidade (PEAD/PEBDL comumente utilizada em filmes de embalagem foi modificada com argila montmorilonita organofílica comercial para obter nanocompósitos com melhores propriedades de barreira. Amostras com 5 e 7,5% de argila (em massa foram estudadas em diferentes condições de processamento. Filmes produzidos com os nanocompósitos foram avaliados quanto à dispersão da argila por difração de raio X e Microscopia Eletrônica de Transmissão. As propriedades de barreira dos filmes foram determinadas pelas medições de permeabilidade ao oxigênio e ao vapor d'água. As propriedades mecânicas e ópticas também foram determinadas. Observou-se uma estrutura com a argila parcialmente esfoliada e intercalada. A permeabilidade ao oxigênio diminuiu significativamente enquanto a permeabilidade à água foi pouco influenciada. As propriedades mecânicas e a transparência dos filmes foram pouco alteradas. O modelo de Nielsen foi aplicado para os dados de permeabilidade relativa e demonstrou ser um ótimo recurso para a avaliação do grau de esfoliação da argila para as diferentes amostras, que foram confirmadas pelas análises realizadas em microscopia eletrônica de transmissão.A typical high density polyethylene and linear low density polyethylene (HDPE/LLDPE blend used in flexible packaging was modified with commercial organophylic montmorilonite clay to obtain nanocomposites with superior barrier properties. Samples with 5 and 7.5% of clay were prepared under different processing conditions. Films produced from the nanocomposites were evaluated in terms of oxygen and water vapor permeation and also by X-ray diffraction and Transmission Electron Microscopy. Tensile and optical properties were also evaluated. The clay showed to be intercalated and partially exfoliated. The oxygen permeation was mainly reduced and the vapor permeation was weakly modified. The mechanical

Tribological investigation of novel HDPE-HAp-Al2O3 hybrid biocomposites against steel under dry and simulated body fluid condition.

Science.gov (United States)

Nath, Shekhar; Bodhak, Subhadip; Basu, Bikramjit

2007-10-01

Among various biocompatible polymers, polyethylene based materials have received wider attention because of its excellent stability in body fluid, inertness, and easy formability. Attempts have been made to improve their physical properties (modulus/strength) to enable them to be used as load bearing hard tissue replacement applications. Among such attempts, high density polyethylene (HDPE)-hydroxyapatite (HAp) composite (HAPEX), has already been developed for total hip replacement (THR) acetabular cup and low load bearing bone tissue replacement. In the present work, alumina has been added as a partial replacement of HAp phase to improve the mechanical and tribological properties of the HAPEX composite. In an attempt to assess the suitability of the developed composite in THR application, the tribological properties against steel counterbody under both in air and simulated body fluid (SBF), have been investigated and efforts have been made to understand the wear mechanisms. The fretting wear study indicates the possibility of achieving extremely low COF (Coefficient of Friction approximately 0.09) as well as higher wear resistance (order of 10(-6) mm(3)/N m) with the newly developed composites in SBF. A low wear depth of approximately 4.6-5.3 microm is recorded, irrespective of fretting environment. The implication of the work is that optimal and combined addition of bioactive and bioinert ceramic filler to HDPE can provide a good opportunity to obtain hybrid biocomposites with better combination of physical properties (modulus, hardness) as well as low friction and high wear resistance.

Densidad de población y su efecto sobre el rendimiento de papa

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Rodríguez Loyla

2004-06-01

Full Text Available

En dos localidades del departamento

de Cundinamarca, el Centro Agropecuario Marengo

(Mosquera, 2.550 m.s.n.m y el Centro ICA San

Jorge (Soacha, 3.100 m.s.n.m, se evaluó el efecto de

la densidad de población (50.000, 125.000, 200.000,

Variação, divergência e correlações genéticas entre caracteres silviculturais e densidade básica da madeira em progênies de Myracrodruon urundeuva (Engler Fr. Allem. Genetic variation, divergence and correlations among silvicultural traits and wood density in progenies of Myracrodruon urundeuva (Engler Fr. Allem.

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Eduardo Luiz LONGUI

2011-06-01

Full Text Available Myracrodruon urundeuva foi muito explorada no passado devido às qualidades de sua madeira e tornou-se escassa em todas as áreas naturais de ocorrência, sendo atualmente considerada como ameaçada de extinção (categoria vulnerável. Isso torna a espécie importante para estudos relacionados à estrutura genética de populações para fins de conservação e melhoramento genético. Assim, a partir de um teste de progênies, instalado em 1987, em Selvíria–MS, foram estimados parâmetros genéticos para a densidade básica da madeira em três posições radiais (medula, intermediária e casca, a distância genética de Mahalanobis e correlações genéticas e fenotípicas entre caracteres de crescimento (altura total, altura do fuste e diâmetro à altura do peito – DAP e densidade básica da madeira. A população apresentou alta densidade básica da madeira (0,75 g.cm-3 e alta herdabilidade (0,64 para este carácter na posição intermediária e na medula, indicando forte controle genético e a possibilidade de melhoramento por seleção. Os resultados também mostraram que para essa população de M. urundeuva deve-se utilizar as progênies 1 e 14 para obtenção de híbridos mais heteróticos por apresentarem maior distância de Mahalanobis; as progênies 14 e 20 por outro lado possuem distâncias muito próxima constituindo pares de progênies semelhantes, o que é interessante para se buscar melhoramento por retrocruzamento. Tais informações são importantes para escolha de métodos adequados de conservação e melhoramento genético.In the past, Myracrodruon urundeuva was intensively exploited due the quality of its wood and became scarce in all natural areas of occurrence, being actually considered in extinction (vulnerable category. This makes the species important for studies of population genetic structure for conservation and breeding purposes. Thus, from a progeny test established in 1987 in Selvíria, Mato Grosso do Sul

A Ligadura Tubária é Fator de Risco para a Redução da Densidade Mineral Óssea em Mulheres na Pós-menopausa?

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Zabaglia Silval Fernando Cardoso

2001-01-01

Full Text Available Objetivo: comparar a densidade mineral óssea de mulheres menopausadas com e sem o antecedente de laqueadura tubária e avaliar quais fatores nos dois grupos poderiam estar associados à densidade mineral óssea no fêmur e coluna lombar. Métodos: foram incluídas 70 pacientes em cada grupo, no ano de 1998, do Centro de Atenção Integral à Saúde da Mulher da Universidade Estadual de Campinas. As mulheres responderam um questionário sobre características clínicas e reprodutivas e foram submetidas à densitometria óssea (Lunar DPX no fêmur e coluna lombar. Os dados foram analisados por meio dos testes t de Student, exato de Fisher, c² de Pearson, t com correção de Bonferroni e regressão múltipla. Resultados: a média etária das laqueadas foi de 53,2 anos e das não-laqueadas de 52,6 anos, com média da idade à menopausa de 48 anos, semelhante nos dois grupos. As médias de idade à cirurgia foi 33,7 anos, com tempo decorrido da cirurgia de 18 anos. A média da densidade mineral óssea para o fêmur e coluna lombar não apresentaram diferenças significativas entre os dois grupos. A distribuição percentual em categorias de T-score do fêmur e coluna lombar não mostrou diferenças significativas nos dois grupos. Na regressão múltipla, observou-se que a idade mostrou uma associação inversa e o índice de massa corporal uma associação direta com a densidade mineral óssea no fêmur. Para a coluna lombar, cor não-branca, paridade, idade à menopausa, escolaridade e índice de massa corporal mostraram uma associação direta e a idade à menarca uma associação inversa com a densidade mineral óssea. Conclusão: a laqueadura tubária não ocasionou redução na massa óssea em mulheres na pós-menopausa.

Modelo dinámico para lámparas de descarga de alta intensidad en alta frecuencia; Dynamic model for high intensity discharge lamps in high frequency

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Leonardo Cedeño Rodríguez

2015-04-01

Full Text Available En este trabajo se desarrolla el modelado dinámico de lámparas de descarga de alta intensidad (HID en inglés, de manera que pueda contribuir al desarrollo posterior de un sistema de control avanzado sobre la etapa de potencia de un balasto electrónico, que permita operar este tipo de lámparas en alta frecuencia. El modelo tiene en cuenta la presencia del fenómeno de la resonancia acústica (RA, que usualmente se presenta en las lámparas HID a frecuencias elevadas. Para el modelado se emplean técnicas híbridas, teniendo como punto de partida las ecuaciones de balance de energía en el interior de la lámpara, en tanto para la parametrización, se aplica identificación de sistemas y optimización mediante algoritmos genéticos. La implementación del modelo se realiza con el software Matlab R2011a. Como resultado se obtiene un modelo dinámico para lámparas HID en alta frecuencia, validado para lámparas de alta presión de sodio.In this paper the dynamic modeling of high intensity discharge lamps (HID is developed. This will contribute to the further development of an advanced control system on the power stage of an electronic ballast, which allows these lamps operate at high frequency. The model must take into account the presence of the acoustic resonance’s phenomenon (AR, which usually occurs when HID lamps operates at high frequency. Hybrid modeling techniques were employed, the balance equations and the empirical expressions were obtained and the model was parameterized by identification techniques and optimization based on genetic algorithms. The implementation of the model has performed using Simulink tool of Matlab R2011a software. As a result, a dynamic model for HID lamps in high frequency has achieved and validated for high-pressure sodium lamps (HPS.

Ocorrência de Trypanosoma evansi em eqüinos no município de Cruz Alta, RS, Brasil Occurrence of Trypanosoma evansi in equines in Cruz Alta, RS, Brazil

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Régis Adriel Zanette

2008-08-01

Full Text Available O objetivo deste trabalho foi relatar a ocorrência de Trypanosoma evansi em eqüinos no município de Cruz Alta, Estado do Rio Grande do Sul, abordando aspectos epidemiológicos e sinais clínicos da infecção. A tripanosomose ocorreu em uma propriedade rural no município de Cruz Alta. Ao exame clínico, observou-se que quatro dos animais apresentavam marcha oscilante, com incoordenação dos membros posteriores. No entanto, eles estavam em bom estado nutricional, sem febre, bem hidratados e alimentavam-se normalmente. Foram coletadas amostras de sangue das éguas para hemograma, sendo identificado aumento das proteínas plasmáticas, leucocitose, eosinofilia e linfocitose em animais com sinais clínicos. No esfregaço sangüíneo periférico, observou-se a forma flagelada do T. evansi em três dos eqüinos.This study aimed at describing the occurrence of Trypanosoma evansi in equines from the city of Cruz Alta, RS, Brazil, relating epidemiological aspects and clinical signs of the infection. The tripanosomiasis occurred in a rural area of Cruz Alta, RS. Clinical signs presented by four animals were stiff and incoordinated gait of the pelvic members, although they were in good nutritional status, without fever, well-hydrated and eating normally. Blood samples were collected from the mares for hemogram. Increased levels of plasmatic proteins, leukocytosis, eosinophilia, and limphocytosis were observed in animals with clinical signs. Flagellated forms of T. evansi were observed in the blood smear of three animals.

77 FR 35669 - AltaGas Renewable Energy Colorado LLC; Supplemental Notice That Initial Market-Based Rate Filing...

Science.gov (United States)

2012-06-14

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. ER12-1875-000] AltaGas Renewable Energy Colorado LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request... of AltaGas Renewable Energy Colorado LLC application for market-based rate authority, with an...

[Preliminary study of constructing tissue-engineered cartilage with the endoskeletal scaffold of HDPE by bone marrow stromal cells].

Science.gov (United States)

Zhu, Lie; Jiang, Hua; Zhou, Guang-Dong; Wu, Yu-Jia; Luo, Xu-Song

2008-09-01

To explore the feasibility of using a nonreactive, permanent endoskeletal scaffold to create the prothesis in special shape which is covered with tissue-engineered cartilage. Porcine BMSCs and articular chondrocytes were isolated and expanded respectively in vitro. Porcine BMSC of passage 1 in the concentration of 10 x 10(7)/ml were seeded onto a cylinder-shaped PGA (1 mm in thickness)/Medpor (3mm in diameter and 5mm in highness) scaffold as the experimental group. After the cell-scaffold constructs were cultured for 5 days, the primary medium, high-glucose DMEM medium with 10% fetal bovine serum (FBS), was replaced by chondrogenically inductive medium for 4 weeks. BMSCs and chondrocytes of the same concentration were seeded respectively onto the scaffold as the negative control group and the positive control group. After cultured in vitro for 4 weeks, the cell-scaffolds construct were implanted into subcutaneous pockets on the back of nude mice. Four and eight weeks later, the formed cartilage prosthesis were harvested and then evaluated by gross view, histology, immunohistochemistry and glycosamino-glycan (GAG) content. Cells in all groups had fine adhesion to the scaffold and could secrete extracellular matrix. All specimens in experimental group and positive control group formed mature cartilage with collagen II expression.The mature catrtilage wraped HDPE compactly and grown into the gap of HDPE. Mature lacuna structures and metachromatic matrices were also observed in these specimens. GAG contents in experimental group were (5.13 +/- 0.32) mg/g (4 weeks), (5.37 +/- 0.12) mg/g (8 weeks). In contrast, specimens in BMSC group showed mainly fibrous tissue. It indicates that it is feasible to create special shaped tissue-engineering cartilage with the permanent internal support using BMSCs as seed cell.

Tillering dynamics of Tanzania guinea grass under nitrogen levels and plant densities=Dinâmica de perfilhamento do capim-tanzânia sob doses de nitrogênio e densidades de plantas

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Manoel Eduardo Rozalino Santos

2012-10-01

Full Text Available This study evaluated the influence of nitrogen levels (N and plant density (D on the tillering dynamics of Tanzania guinea grass (Panicum maximum Jacq.. Treatments were arranged in a completely randomized block design with 12 treatments and two replicates in a factorial scheme (4 × 3 with four levels of N (0, 80, 160 or 320 kg ha-1 N and three plant densities (9, 25, and 49 plant m-². Higher number of tillers was observed in the treatment with 9 plants m-² and under higher levels of N, especially in the second and third generations. Still, the N influenced quadratically the appearance rate of basal and total tillers, which were also affected by plant density and interaction N × D. However, the appearance rate of aerial tiller was not influenced by factors evaluated. The mortality rate of total tiller was influenced quadratically by the nitrogen levels and plant densities. The mortality rate of basal tiller responded quadratically to plant density, whereas the mortality rate of aerial tiller increased linearly with fertilization. Pastures with low or intermediate densities fertilized with nitrogen, presented a more intense pattern of tiller renewal. Objetivou-se com este trabalho avaliar o efeito de doses de nitrogênio (N e densidades de plantas (D sobre a dinâmica de perfilhamento do capim-tanzânia (Panicum maximum Jacq.. O delineamento foi em blocos casualizados, com 12 tratamentos e duas repetições em esquema fatorial 4 × 3, com quatro doses de N (0, 80, 160 ou 320 kg ha-1 ano-1 e três densidades de plantas (9, 25 ou 49 plantas m-². O número de perfilhos foi maior na densidade de 9 plantas m-² e nas maiores doses de N, principalmente na segunda e terceira gerações. O N influenciou quadraticamente as taxas de aparecimento de perfilhos basilares e totais, que também foram influenciadas pela densidade de plantas e pela interação N × D. A taxa de aparecimento de perfilhos aéreos, no entanto, não foi influenciada pelos fatores

[Epidemiology of urinary calculi in the Marina Alta (Alicante) region].

Science.gov (United States)

Romero Pérez, P; Amat Cecilia, M

1992-06-01

An epidemiological study on urolithiasis was conducted in the Borough of Marina Alta from December 1989 to December 1990. The Health Care region of Marina Alta includes 11 health care areas, all centralized into one single Local Hospital offering service to an estimated population of 125,290 inhabitants, which experiences a remarkable increase over the summer months. During the study period 1,792 patients, 350 (20%) of which were lithiasis cases were seen in the Urology Unit. 2.80 per thousand of the studied population had urolithiasis-related signs. Incidence is higher in males than in females, as well as in patients with prior lithiasic diseases, surgery and urinary infections. Urinary infection was present in 20% of patients. Nine percent of patients had some type of associated urinary malformation. The most frequent mineral composition of the lithiasis was: Calcium oxalate (52%), uric acid (20%) and oxalate plus uric acid (9%).

EFECTO DE LA TEXTURA DE ELECTRODEPÓSITOS DE ZINC EN ACERO SOBRE SU RESISTENCIA A LA CORROSIÓN

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Zulema A. Mahmud

2010-01-01

Full Text Available En este trabajo, las texturas de depósitos de zinc en acero templado se correlacionan con la resistencia de corrosión del metal base. Se estudian por difracción de rayos X las texturas de electrodepósitos de zinc. Los depósitos de zinc se realizaron simulando las condiciones industriales de temperatura, tiempo y densidad de corriente, utilizando soluciones de electrodeposición de ZnCl2 + NH4Cl en presencia y ausencia de tiourea. Según se ha reportado, los depósitos de Zn con una alta intensidad en la textura de los planos basales (0,0,2 y bajas intensidades en la textura de planos piramidales (del tipo (1,0,3, (1,1,2, (2,0,1 presentan mayor resistencia a la corrosión. Para tiempos de electrodeposición bajos, los cincados obtenidos desarrollan una textura (1,0,3 y las densidades de corriente de corrosión son altas. Mientras que, para tiempos de deposición altos (10 minutos, los cincados tienen una textura (0,0,2 y el valor de la corriente de corrosión disminuye notablemente. La preponderancia de la textura (0,2,2 en los planos basales y la baja intensidad de DRX para la textura (0,0,3 en los planos piramidales, están asociados a los depósitos que presentan una alta resistencia a la corrosión.

Altas habilidades: uma questão escolar Giftedness: a shool matter

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Célia Maria Paz Ferreira Barreto

2011-12-01

Full Text Available Esse estudo foi realizado em uma escola federal de ensino, localizada no Rio de Janeiro. Estabeleceu como objetivos gerais investigar as representações dos professores sobre as altas habilidades e a existência da indicação de alunos com esse perfil para atendimento. Utilizou duas amostras diferenciadas. A primeira, formada por 36 professores que atuavam do 1º ao 9º ano do ensino fundamental e do 1º ao 3º ano do ensino médio. A outra amostra foi constituída por quatro setores da escola responsáveis pelo registro histórico dos alunos. Utilizou-se a metodologia da análise de conteúdo no tratamento dos dados obtidos. Os resultados mostraram que os professores respondentes têm representações sobre altas habilidades e que não existem alunos com altas habilidades matriculados na instituição. Os resultados indicam urgência no implemento de ações inclusivas para as altas habilidades nessa escola, assim como a continuidade e aprofundamento nessa pesquisa.The study took place in a public federal school in Rio de Janeiro. The overall objectives were to investigate representations teachers have about giftedness and existing indications of such students that should be referred to specific learning and counseling programs. Two different groups were taken as samples. The first was made up of 36 elementary and high school teachers. The other consisted of four school sectors, charged with keeping students data records. The qualitative method of contents analysis was used. This study indicates its participants have representations about giftedness, although there were no gifted students enrolled in the institution where the study took place. The results also suggest that there is a pressing need to implement inclusive actions for gifted students at this school, as well as further developing the investigation at a deeper level.

Estabilidad fenotípica y densidades de planta de genotipos de estevia (Stevia rebaudiana Bert. en la región Caribe de Colombia

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Jarma Orozco Alfredo

2011-06-01

Full Text Available Los estudios de estabilidad fenotípica son importantes para la siembra de genotipos que muestranun adecuado comportamiento en una o varias zonas. Estevia (Stevia rebaudiana Bert. es una especierecientemente introducida en Colombia, por tanto, los estudios sobre su adaptación en áreas productorasdel país son escasos. Esta planta se caracteriza por sintetizar glucósidos de diterpeno altamenteedulcorantes con bajo aporte calórico. El presente estudio se realizó en Montería (8º 52' N y 76º 48'O, Colombia, con el objeto de determinar la estabilidad fenotípica de los genotipos Morita 1 y Morita 2de estevia, sembrados en tres densidades de plantas (25, 12.5 y 6.25 plantas/m2 y dispuestos en undiseño de bloques completos al azar, en tres épocas de siembra en el Caribe húmedo de Colombia. Losresultados más importantes señalan que Morita 2, en densidades de 25 plantas/m2, registró los mejoresíndices de estabilidad para el rendimiento de hoja seca/ha (Pig = 0; Pid = 0. Por su parte, éste mismogenotipo presentó una mayor relación hoja/tallo (1.17 ± 0.3 y mayor contenido de glucósidos totales(0.1586 ± 0.024 cuando la radiación solar fue mayor y las densidades eran entre 12.5 y 25 plantas/m2.

EVALUACIÓN DE DENSIDADES DE SIEMBRA EN Solanum sessiliflorum dunal “COCONA” Y SU EFECTO EN EL RENDIMIENTO DE FRUTO

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Rodrigo Gonzales Vega

2012-12-01

Full Text Available La cocona es una especie vegetal nativa de América Tropical, cuyos frutos maduros son ricos en hierro, vitamina B5 (Niacina, se utilizan en la preparación de jugos, refrescos, jarabes y ensaladas. El estudio se realizó en el Campo Experimental “El Dorado” de Estación Experimental San Roque, del INIA Loreto con el objetivo principal de determinar el mejor distanciamiento para establecer plantaciones comerciales de Solanum sessiliflorum dunal “Cocona”, en condiciones de suelos no inundables o de altura. Se evaluaron cuatro densidades de siembra 2,0m x 2,0m; 1,5m x 1,5m, 2,0m x 1,0 y 1,5m x 1,0m. Las variables evaluadas fueron el número de frutos, peso de frutos y rendimiento de frutos por cada tratamiento en estudio, el diseño experimental utilizado fue Bloques Completos al Azar (DBCA, con cuatro repeticiones, los datos fueron analizados mediante el Análisis de Variancia y Prueba Estadística de Tukey, usando el software SPSS, versión 10. De los resultados Obtenidos se determinó que la densidad 1,5m x 1,0m (6 666 plantas/ha, produjo el mejor rendimiento con 14 600 kg/ha de fruto, superando significativamente a los tratamientos 2m x 1,0, 1,5m x 1,5m y 2,0 x 2,0m, que alcanzaron rendimientos de fruto de 12020, 11 330 y 10 570 kg/ha, respectivamente. Se concluye que la densidad de siembra influye en el rendimiento de fruto, así a menor número de plantas, mayor número y peso de fruto por planta se obtiene un menor rendimiento de fruto/ha.

Effects of Rice Husk Modification with Liquid Natural Rubber and Exposure to Electron Beam Radiation on the Mechanical Properties of NR/ HDPE/ Rice Husk Composites

International Nuclear Information System (INIS)

Lane, C.E.; Ishak Ahmad; Ibrahim Abdullah; Dahlan Mohd

2011-01-01

Rice husk (RH) powder is a natural fibre capable of reinforcing natural rubber thermoplastic (TPNR) NR/ HDPE composites on specific modification of the particle surface. In this study the modification of RH powder involved pre-treatment with 5 % sodium hydroxide (NaOH) solution, soaking in LNR solution and exposure of LNR coated RH to electron beam (EB) irradiation. Preparation of NR/ HDPE/ RH composites was via melt-mixing in an internal mixer at predetermined conditions. Morphology study of the composites using scanning electron microscope (SEM) showed a homogeneous distribution of modified RH particles and particle-matrix interaction in the composite. Modified RH filled composites exhibited a significant change in mechanical properties. The maximum stress and impact strength were 6.7 MPa and 13.2 kJ/ m 2 , respectively at 20 kGy radiation, while the tensile modulus was 79 MPa at 30 kGy dose. The interfacial RH-TPNR interaction for the LNR-EB treated RH particles had improved in the EB dosage range of 20-30 kGy. However, over exposure to radiation caused degradation of rubber coat and interaction between particles to increase. Agglomeration of filler particles would occur and caused inhomogeneous distribution of filler in the composite. (author)

The effects of new diversion valves in Alta hydro-power station on the population of Atlantic salmon; Ny forbitappingsventil i Alta kraftverk. Betydning for laksebestanden

Energy Technology Data Exchange (ETDEWEB)

Forseth, Torbjoern; Naesje, Tor F.; Jensen, Arne J.; Saksgaard, Laila; Hvidsten, Nils Arne

1997-02-01

The report deals with consequential relations for the environment of Alta river in Northern Norway in connection with a hydroelectric power plant. The consequences of regulating the flow by the installation of an new diversion valve are discussed. 39 refs., 10 figs., 4 tabs.

Estimación poblacional y conservación de felinos (Carnivora: Felidae en el norte de Quintana Roo, México

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Dulce María Ávila-Nájera

2015-09-01

Full Text Available Resumen:La estimación de la densidad de fauna silvestre permite tener una idea del estado de salud de las poblaciones y en algunos casos indica el estado de conservación de los ecosistemas. Los métodos de evaluación deben hacer estimaciones no sesgadas, ya que servirán de base para estrategias de conservación de especies clave. Algunas regiones en México han sido identificadas como áreas de alta prioridad para la conservación de especies con cierto nivel de riesgo, como es la Península de Yucatán (PY, donde prevalece la mayor población de jaguares en México. Sin embargo, poco se sabe acerca de la situación actual de los felinos amenazados y en peligro de extinción, como un grupo de especies que conviven en la parte noreste de la Península. Nuestro objetivo fue estimar la densidad de las poblaciones de felinos silvestres a mediano plazo en la Reserva Ecológica El Edén (EEER y sus alrededores. Se llevaron a cabo muestreos con cámaras-trampa durante cuatro años (2008, 2010, 2011 y 2012, se usaron modelos de captura-recaptura para poblaciones cerradas (CAPTURA + MMDM o VMMDM y un modelo de C-R espacial-mente explícito (CERC por medio del paquete SPCACAP para realizar las estimaciones de densidad. Las especies estudiadas fueron: jaguar (Panthera onca,puma (Puma concolor,ocelote (Leopardus pardalis,jaguarundi (Puma yaguaroundiy tigrillo (Leopardus wiedii.La frecuencia de captura se obtuvo para las cinco especies y la densidad para tres (individuos/100km2. La densidad estimada por medio de MMDM varió entre 1.2 y 2.6 para jaguares, pumas (1.7-4.3 y ocelotes (1.4-13.8. Las estimaciones de la densidad en SPACECAP variaron desde 0.7 hasta 3.6 para jaguares, de 1.8 a 5.2 para pumas y de 2.1 a 5.1 en ocelotes. El método de C-R espacialmente explícito (SECR, SPACECAP tiene menos probabilidades de sobrestimar la densidad, lo que provee una herramienta útil en el proceso de planificación y toma de decisiones para la conservación de

Densidad, crecimiento y supervivencia de juveniles de Lyropecten (Nodipecten nodosus (Pteroida: Pectinidae en cultivo suspendido en el Golfo de Cariaco, Venezuela

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Vanessa Acosta

2000-12-01

Full Text Available El efecto de la densidad sobre el crecimiento y la supervivencia de juveniles del pectínido Lyropecten nodosus se estudió en condiciones de cultivo intermedio en el Golfo de Cariaco, Estado Sucre, Venezuela (diciembre 93 - julio 94. Se evaluaron seis densidades de siembra (7, 15, 30, 60, 125 y 250 ejemplares/cesta con una longitud y una masa seca inicial de 9.4 + 0.18 mm y 0.007 + 0.0026 g, respectivamente. Los juveniles fueron colocados en cestas japonesas "pearl nets" y posteriormente suspendidas en un "long line" a 8 m de profundidad. Los patrones de crecimiento en cada uno de los compartimientos del soma fueron similares, pero con magnitudes diferentes e inversamente proporcionales a la densidades de cultivo; sin embargo, la supervivencia no fue afectada significativamente, sugiriendo que la competencia intraespecífica de los organismos en cultivo provocó un estrés notable, aunque insuficiente para causar mortalidad. Los resultados y estrategias proyectadas para el cultivo intermedio de L. nodosus sugieren un procedimiento de disminución de la densidad de organismos a través de desdobles sucesivos en un período de cultivo de seis meses obteniendo tallas cercanas a los 50 mm para comenzar el cultivo de engorde.The effect of culture density on growth and survival of juveniles was studied in the scallop Lyropecten nodosus with intermediate hanging cultures in Golfo de Cariaco, Sucre state, Venezuela, from December 1993 to July 1994. Six spat-densities (7, 15, 30, 60, 125 and 250 scallops/nets were evaluated. The initial shell height and dry mass tissue were 9.4 + 0.18 mm and 0.007 + 0.0026 g, respectively. The specimens were placed into pearl nets and suspended in a long line at 8 m depth. Growth patterns of somatic tissue were similar, but with different magnitudes and inverse proportionality to culture density. No effect of density was observed on survival. These results suggest that intraspecific competition of cultivated scallops

Fertilización de base en un cultivo inicial de pecan con dos marcos de plantación de alta densidad Effect of different fertilization strategies on pecan growth parameters under two high density plantation frames

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Lidia Giuffré

2011-07-01

Full Text Available El pecán, Carya illinoensis Koch, es una especie cuyo fruto es reconocido como un alimento altamente saludable. Su cultivo se encuentra en expansión en la Argentina pero existen muy pocas investigaciones sobre fertilización y sistemas de plantación. Los objetivos del trabajo fueron caracterizar algunas propiedades físico-químicas y químicas de un suelo en el que se inicia un cultivo de pecán, y comparar tratamientos de fertilización de base (FB en dos marcos de plantación de alta densidad (MP. Se realizó una plantación de pecán en Villanueva (provincia de Buenos Aires, sobre un suelo Hapludol taptoárgico, con dos marcos de plantación: 10 x 10 m (marco real: MR y 8 x 8 m (tresbolillo: TR. El diseño del experimento fue en parcelas divididas con cuatro repeticiones. La parcela principal fueron los dos marcos de plantación, y las subparcelas fueron los distintos tratamientos de fertilización base: Compost (C, Fósforo (P, Nitrógeno (N y Control sin fertilización base (T. Las determinaciones para evaluar el crecimiento de las plantas de pecán fueron: la altura de las plantas y el diámetro del tronco. Con respecto a la fertilidad del suelo, la fertilización fosforada y el agregado de compost permitieron aumentar significativamente los niveles de P-Bray. El tratamiento con fertilización orgánica: compost, presentó un incremento significativo en altura de los pecanes en el marco de plantación 8 x 8 m, que no se manifestó en ningún caso en los diámetros del tronco, con una interacción MP x FB significativa (P=0,01 para la variación de altura al primer año. La variación del volumen del árbol durante el año de experimentación no presentó efectos significativos según el marco de plantación ni la fertilización base aplicada.The fruit of the pecan tree, Carya illinoensis Koch, is considered a very healthy food. In Argentina, pecan cultivation has been expanding rapidly but very little research has been conducted on

Fatores de risco cardiovascular e consumo alimentar em cadetes da Academia da Força Aérea Brasileira

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Fernanda Elisabete Hilgenberg

2016-04-01

Full Text Available Resumo O objetivo deste artigo é investigar a prevalência de fatores de risco cardiovascular e inadequações de consumo alimentar em cadetes da Academia da Força Aérea Brasileira e a associação com sexo e ano de formação. Estudo transversal com 166 cadetes da Academia da Força Aérea Brasileira, em Pirassununga – SP, entre junho e dezembro de 2013. Foram avaliadas medidas antropométricas, parâmetros bioquímicos e clínicos, nível de atividade física, tabagismo e consumo alimentar. Testes de Qui-Quadrado de Pearson ou Exato de Fisher foram utilizados. A prevalência de excesso de peso (IMC >25,0 kg/m2 foi de 29,7% nos homens e de 16,7% nas mulheres. Hipertensão arterial foi prevalente em 15,2% dos homens. Verificou-se hipercolesterolemia em 50,7% dos cadetes; 24,3% apresentaram valores elevados de lipoproteína de baixa densidade e, 11,2%, lipoproteína de alta densidade baixa. Houve associação entre tempo de permanência na Academia e lipoproteína de alta densidade baixa. Observou-se consumo elevado de gorduras saturadas (87,2% e de colesterol (42,7%. A ingestão inadequada de fibras foi verificada em 92,7% da amostra. Observou-se considerável prevalência de fatores de risco cardiovascular entre os cadetes, principalmente hipercolesterolemia e consumo alimentar inadequado.

Effects of larval crowding on development time, survival and weight at metamorphosis in Aedes aegypti (Diptera: Culicidae

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Arnaldo MACIÁ

2009-01-01

Full Text Available Los efectos del hacinamiento larval sobre el tiempo de desarrollo, la supervivencia y el peso en la metamorfosis fueron estudiados en el mosquito del dengue, Aedes aegypti L., en el laboratorio. Se criaron cohortes de larvas en 7 densidades (4, 8, 16, 32, 64, 128 y 256 larvas/ recipiente de 175 ml mientras se mantuvo constante el volumen de agua y la calidad y cantidad de alimento, bajo fotoperíodo y temperatura controlados. Se usaron detritos naturales, principalmente hojas, obtenidos de contenedores colonizados naturalmente por A. aegypti como fuente de nutrientes para las larvas. En cada densidad se registraron el tiempo de desarrollo, la mortalidad, el peso en la metamorfosis y la biomasa total. El tiempo de desarrollo varió entre 4 y 23 días en los machos, y 5 a 24 días en hembras; fue más prolongado a la densidad de 64 (en las hembras y 128 (en los machos larvas por recipiente. En densidades altas la proporción de sexos favoreció los machos. Hubo un incremento en la mortalidad en densidades iguales o mayores que 0,4 larvas/ ml (0,32 larvas/cm2. Se detectó una relación inversa entre la densidad larval y el peso de las pupas. La biomasa por individuo alcanzó un valor asintótico de aproximadamente 1 mg/individuo en una densidad de 128 individuos/ recipiente (0,64 larvas/cm2. Las poblaciones de A. aegypti, cercanas a su extremo sur de distribución, serían sensibles al hacinamiento en pequeños contenedores de agua.

Factores de riesgo cardiovascular en estudiantes universitarios chilenos

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Chiang-Salgado María Teresa

1999-01-01

Full Text Available OBJETIVO: Evaluar la prevalencia de factores de riesgo cardiovascular en universitarios asintomáticos de ambos sexos, de entre 18 y 25 años de edad. MATERIAL Y MÉTODOS: La muestra quedó integrada por 1 301 estudiantes. En una submuestra de 293 sujetos se midieron lípidos séricos, con un analizador químico Hitachi 717. La obesidad se estimó considerando el índice de masa corporal (IMC; el antecedente familiar de infarto, así como el consumo de cigarrillos y el nivel de actividad física se determinaron mediante un cuestionario de autoevaluación. Se construyeron tablas de contingencia para estudiar asociaciones entre factores de riesgo lipídicos y no lipídicos, usando la prueba ji² de Pearson. Se realizó un análisis de regresión múltiple para determinar la relación de cada una de las variables lipídicas (colesterol total, colesterol-lipoproteína de baja densidad, colesterol-lipoproteína de alta densidad y triglicéridos, así como de las no lipídicas (edad, peso, estatura, IMC, sexo, presión arterial, conducta sedentaria y antecedente familiar de infarto precoz. RESULTADOS: Se encontraron niveles de riesgo lipídico en 29.2% de los casos para colesterol total, en 16.2% para lipoproteína de baja densidad y en 5% para lipoproteína de alta densidad. Entre los factores de riesgo no lipídicos más prevalentes, estaban el consumo de cigarrillos, con 46.1%, y el sedentarismo, que alcanzó 60.8%. La obesidad, la hipertensión arterial y el antecedente familiar alcanzaron 1.9, 4.6 y 11%, respectivamente. Se observó una asociación entre el perfil lipídico de riesgo, la obesidad, la conducta fumadora y el antecedente familiar. CONCLUSIONES: Los resultados mostraron una alta prevalencia de sedentarismo y conducta fumadora, asociada a un perfil lipídico de riesgo. Se deduce la necesidad imperiosa de diseñar programas de intervención con el fin de modificar el estilo de vida y prevenir la posible presencia de enfermedades

SU-E-I-45: Measurement of CT Dose to An HDPE Phantom Using Calorimetry: A Feasibility Study.

Science.gov (United States)

Chen-Mayer, H; Tosh, R; Bateman, F; Zimmerman, B

2012-06-01

Radiation dose in CT is traditionally evaluated using an ionization chamber calibrated in terms of air kerma in a phantom of specific dimensions. The radiation absorbed dose, J/kg, can also be realized directly by measuring the temperature rise in the medium. We investigate using this primary method to determine the CT dose at a point (a few mm), using the recently proposed (APMM TG220) high density polyethylene (HDPE) phantom as a medium. The calorimeter detection scheme is adapted from the second generation NIST water calorimeter using sensitive thermistors in a Wheatstone bridge powered by a lock-in amplifier. The temperature sensitivity is about 3 microK. The expected temperature rise in PE is about 0.6 mK per Gy. The thermistor sensors were placed inside a 26 cm dia. × 10 cm HDPE phantom. Two preliminary tests were made: at a linear accelerator with a 6 MV photon beam, and at a 16-slice CT scanner with a 120 kV beam, each with the thermal sensor and with a calibrated ionization chamber. The 6 MV photon beam with 10 on/off cycles at 60 s each yielded the (uncorrected) run-to-run average dose of 3.06 Gy per cycle (sdm 0.3%), about 8% higher than the Result from the ionization chamber (calibrated in terms of absorbed to water). The CT measurements were also made in the middle section of the TG200 30 cm phantom. Twenty consecutive axial scans at 250 mA, which delivers a nominal accumulated dose (CTDIvol) of 705 mGy in 50 s at three axial and three radial locations were measured. The accumulated dose measured by the ionization chamber at the center of the smaller phantom was 347 mGy. The calorimeter data show qualitative tracking of the chamber measurements. Detailed thermal and electrical analysis of the system are planned to obtain quantitative results. © 2012 American Association of Physicists in Medicine.

Digital radiographic evaluation of optical density of porcelains used for fabrication of inlay/onlay prosthesis Avaliação da densidade óptica de porcelanas usadas para confecção de próteses inlay/onlay por meio de radiografia digital

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Júlio Cezar de Melo Castilho

2006-01-01

Full Text Available The purpose of this article was to compare the mean value of optical density of four porcelains commonly used for fabrication of inlay/onlay prostheses using direct digital radiograph. The sample consisted of 20 2-mm thick porcelain specimens (measured by digital pachymeter: Empress (Ivoclair, Simbios (Degussa, Vita Omega 900 and Vitadur Alpha (Vita Zahnfabrik. The values of optical density of the specimens were expressed in millimeters aluminum equivalent (mm eq Al. The samples were X-rayed using two charge coupled devices (CCD - RVG (Trophy - Visualix (Gendex and a phosphor plate system - Digora (Soredex. The optical density reading was performed with Image Tool 1.28 in a total of 110 measurements. Statistical analysis showed that there were statistically significant differences in all materials studied (p Objetivo desse trabalho é comparar valores médios de densidade óptica de quatro porcelanas comumente utilizadas para confecção de inlay/onlay por meio da densidade óptica usando radiografia digital. A amostra constou de 20 corpos de prova com espessura de 2mm (mensurados em paquímetro digital das porcelanas: Empress (Ivoclair, Simbios (Degussa, Vita Omega 900 e Vitadur Alpha (Vita Zahnfabrik. Os valores de densidade óptica das amostras foram expressos em milímetros equivalente em alumínio (mm eq Al. Os espécimes foram radiografados, utilizando dois sistemas de dispositivo de carga acoplada (CCD - RVG (Trophy - Visualix (Gendex e um sistema de placa de fósforo - Digora (Soredex. A leitura da densidade óptica foi realizada no programa Image Tool 1.28 totalizando 110 medições. As leituras de densidade ópticas foram feitas no programa Image Tool 1.28 totalizando 110 mensurações. A análise estatística demonstrou que houve diferença estatisticamente significante entre a densidade óptica das porcelanas estudadas independentemente do sistema de radiografia empregado (p < 0,05. A porcelana Omega 900 obteve 1,8988mmeq

Movimento e inativação do metribuzin em materiais de dois solos, sob diferentes densidades aparentes Movement and inactivation of metribuzin in two soil materials with different bulk densities

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L.E.F. Fontes

1980-06-01

Full Text Available Numa série de ensaios em laboratório e casa-de-vegetação, estudou-se a mobilidade e a inativação do herbicida metribuzin em materiais de um Latossolo e de um Podzólico representativos de duas regiões do Estado de Minas Gerais, em função de diferentes densidades aparentes. Ensaios biológicos foram utilizados para medir a inativação e a mobilidade do metribuzin nos diferentes solos e densidades. A densidade aparente alterou de forma pronunciada a quantidade de herbicida lixiviado através das colunas dos materiais dos solos estudados. Quanto maior a densidade, menor a quantidade de herbicida lixiviado. A quantidade de herbicida que permaneceu biologicamente ativo ao longo da coluna foi diretamente relacionada com a densidade, em cada solo. A mobilidade do metribuzin no material do Latossolo foi maior que no de Podzólico, em consequência de maior atividade coloidal deste.The leaching and inactivation of metribuzin were studied with materials of two mineral soilsat different bulk densities. Plastic tubing of' 7.25 cm diameter and 10 cm height were filled up with different amounts of soil to get different bulk densities. One kg/ha of a.i. of metribuzin placed on the surface are a of the column was le ached through these soil colums using 250 ml of water. The cotyledon disk bioassay method was used to detect the metribuzin leachet. The biological active metribuzin in the soil colunn at different depths, and the inativation abil ity of the soils were determined using the assay with cucumber (Cucumis sativus L. as test-plant. The increase of bulk density reduced the leaching and enhanced the biologically active metribuzin in the soil column. Metribuzin was more mobil in the Red -yellow Lato ssol and more inactivated in the Red-yellow Podzolic soils.

Variação espacial e temporal de larvas de Odonata associadas com macrófitas aquáticas em duas lagoas da planície de inundação do alto rio Paraná, Brasil Spatial and temporal variation of Odonata larvae associated with macrophytes in two floodplain lakes from the upper Paraná River, Brazil

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Gilza Maria de Souza Franco

2002-05-01

Full Text Available Amostras de macrófitas aquáticas foram coletadas de março de 1992 a fevereiro de 1993, nas lagoas do Guaraná (Eichhornia azurea e dos Patos (E. crassipes e E. azurea. Na lagoa do Guaraná, a maior densidade e a maior diversidade foram registradas nas águas altas, com dominância de Telebasis e Acanthagrion, enquanto na lagoa dos Patos a maior densidade e a maior diversidade foram verificadas na fase de águas baixas. Os táxons dominantes na lagoa dos Patos foram Telebasis, Acanthagrion, Neoneura (?,Coryphaeschna adnexa, Miathyria, Diastatops intensa e Erythemis. A lagoa dos Patos diferenciou-se da lagoa do Guaraná principalmente pela alta densidade de C. adnexa, Miathyria, D. intensa e Erythemis, sugerindo que a morfologia de E. crassipes abrigue maior número de invertebrados. A variação do nível hidrométrico dos rios influenciou na concentração de oxigênio dissolvido e pH. Essa variação foi um dos fatores determinantes na flutuação mensal da densidade das larvas. A diferença entre as lagoas, mostrada na análise DCA, deveu-se, principalmente, à variação da densidade de Odonata.Samples of aquatic macrophytes were collected on Guaraná (Eichhornia azurea and Patos (E. crassipes and E. azurea Lakes from March 1992 to February 1993. On Guaraná Lake the highest density and diversity were registered during the high water phase with dominance of Telebasis and Acanthagrion, while on Patos Lake, highest density and diversity were observed during the low water phase. The dominant taxa on Patos Lake were Telebasis, Acanthagrion, Neoneura (?,Coryphaeschna adnexa, Miathyria, Diastatops intensa and Erythemis. DCA and ANOVA differentiated Patos Lake mainly, because of the high abundance of C. adnexa, Miathyria, D. intensa and Erythemis which may be due to morphology of E. crassipes that shelters larger number of invertebrates. Water level variation of rivers influenced concentration of dissolved oxygen and pH. This variation was

MATÉRIA SECA E ABSORÇÃO DE NUTRIENTES EM FUNÇÃO DO ESPAÇAMENTO E DA DENSIDADE DE SEMEADURA EM ARROZ DE TERRA ALTA DRY MATTER AND NUTRIENT UPTAKE OF DRYLAND RICE RELATED TO ROW SPACING AND PLANT POPULATION

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Carlos Alexandre Costa Crusciol

1999-01-01

Full Text Available Foi instalado um experimento em condições de campo, em um Latossolo Vermelho escuro, epi-eutrófico, textura argilosa, em Selvíria-MS, com arroz de sequeiro cv. IAC 201, estudando-se três espaçamentos entre fileiras (30, 40 e 50 cm e três densidades de semeadura (100, 150 e 200 sementes viáveis/m2. Foram avaliadas a produção de matéria seca da parte aérea no momento do florescimento e determinados os teores e quantidades de N, P, K, Ca, Mg e S absorvidos, assim como a eficiência de utilização de nutrientes. A redução do espaçamento entre fileiras aumentou a produção de matéria seca da parte aérea e a quantidade de nutrientes absorvidos. A variação da densidade de semeadura não afetou os parâmetros estudados. A redução do espaçamento entre fileiras proporcionou maior eficiência de utilização do Ca e diminuiu a do N e Mg. Os teores de nutrientes na matéria seca da parte aérea não foram afetados pela variação do espaçamento entre fileiras.A field experiment was conducted in a clayey Dark Red Latosol in Selviria, MS, Brazil, to study the effect of three row spacings (30, 40 and 50 cm and three seed densities (100, 150 and 200 viable seeds/m2 on plant dry matter yield, macronutrient (N, P, K, Ca, Mg and S uptake at flowering, and the nutrient use efficiency. A decrease in row spacing led to an increase in shoot dry matter production and nutrient uptake. There was no effect of plant densities on dry matter or nutrient uptake. The decrease in row spacing allowed a higher Ca use efficiency, but not for N and Mg. The concentration of the macronutrients in the shoots was not affected by spacing.

Estabilidad fenotípica y densidades de planta de genotipos de estevia (Stevia rebaudiana Bert. en la región Caribe de Colombia

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Alfredo Jarma Orozco

2011-04-01

Full Text Available Los estudios de estabilidad fenotípica son importantes para la siembra de genotipos que muestran un adecuado comportamiento en una o varias zonas. Estevia (Stevia rebaudiana Bert. es una especie recientemente introducida en Colombia, por tanto, los estudios sobre su adaptación en áreas productoras del país son escasos. Esta planta se caracteriza por sintetizar glucósidos de diterpeno altamente edulcorantes con bajo aporte calórico. El presente estudio se realizó en Montería (8° 52' N y 76° 48' O, Colombia, con el objeto de determinar la estabilidad fenotípica de los genotipos Morita 1 y Morita 2 de estevia, sembrados en tres densidades de plantas (25, 12.5 y 6.25 plantas/m² y dispuestos en un diseño de bloques completos al azar, en tres épocas de siembra en el Caribe húmedo de Colombia. Los resultados más importantes señalan que Morita 2, en densidades de 25 plantas/m², registró los mejores índices de estabilidad para el rendimiento de hoja seca/ha (Pig = 0; Pid = 0. Por su parte, éste mismo genotipo presentó una mayor relación hoja/tallo (1.17 ± 0.3 y mayor contenido de glucósidos totales (0.1586 ± 0.024 cuando la radiación solar fue mayor y las densidades eran entre 12.5 y 25 plantas/m².

Fabrication and Characterization of Micro- and Nano- Gd2O3 Dispersed HDPE/EPM Composites

International Nuclear Information System (INIS)

Uhm, Young Rang; Kim, Jae Woo; Jun, Ji Heon; Lee, Sol; Rhee, Chang Kyu

2010-01-01

Hydrophobic polymer mixed with Gd 2 O 3 can be used in nuclear industry as a neutron shield because of its neutron attenuating and absorbing property, while it was reported that the smaller particles dispersed polymer composites can enhance radiation shielding efficiency compared to larger particles dispersed ones. However, preparations of such materials are difficult because of the poor dispersion of the fine particles in the polymer matrix. Surface modification of the nanoparticles is therefore required for the homogeneous dispersion of the particles in the polymer matrix. In this study, pulverization of the micro-Gd 2 O 3 particles and simultaneous surface coating of the nanoparticles by polymeric surfactant low density polyethylene (LDPE) were performed by using one-step of high energy wet ball-mill. Dispersion and neutron shielding effect of the nano- and micro-Gd 2 O 3 fillers in mixed polymer of ethylene propylene monomer (EPM) and high density polyethylene (HDPE) were examined

Efeito da Densidade de Criação e do Sexo Sobre o Empenamento, Incidência de Lesões na Carcaça e Qualidade da Carne de Peito de Frangos de Corte

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Garcia RG

2002-01-01

Full Text Available O experimento foi conduzido nas instalações experimentais da Faculdade de Medicina Veterinária e Zootecnia - UNESP, Campus de Botucatu, SP, Brasil, com o objetivo de avaliar o efeito da densidade de criação e do sexo sobre o empenamento, incidência de lesões na carcaça e a qualidade de carne de peito de frangos de corte. Foram utilizados 1950 pintos de corte sexados, da linhagem Ross, distribuídos em um delineamento inteiramente casualizado, com esquema fatorial com 3 densidades (10, 13 e 16 aves/m² e dois sexos com 5 repetições, sendo que uma foi destinada exclusivamente para reserva, criados até os 42 dias de idade. Aos 28, 35 e 42 dias foram amostradas 3 aves por repetição para a determinação do empenamento através da porcentagem de penas e 10 aves para a determinação do escore de empenamento. Também aos 42 dias de idade todas as aves foram identificadas na pata com anilhas numeradas e submetidas à avaliação da incidência de lesões na pele. Foram escolhidas ao acaso 5 aves por repetição para a determinação da qualidade da carne de peito. Pode-se concluir que o aumento na densidade de criação promoveu uma diminuição na velocidade de empenamento e, conseqüentemente, uma maior incidência de lesões na carcaça. O comprimento, a largura e a espessura do peito foram menores para as aves criadas na maior densidade, e a perda de peso por cozimento foi maior para as aves criadas na maior densidade.

Ventajas de los motores de flujo axial

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Alberto M Basanta Otero

2011-03-01

Full Text Available Es importante conocer sobre una familia de motores que a diferencia de los convencionales o tradicionales no presentanun flujo rotatorio radial, denominados motores de flujo axial. Dichos motores presentan altos valores de par motriz abajas velocidades, una alta eficiencia y alta densidad de potencia. Este trabajo constituye un breve análisis dealgunos motores de la referencia bibliográfica.  Is important to know about a family of motors that at difference whit the traditional, don't have a rotator radial flux,called, axial flux motors. These motors have high torque for low speed, high efficiency and high power density. Thiswork is a brief analysis of several motors of the bibliographic references.

Technology for Salt Production in the Mixteca Alta

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Ricardo Antonio León Hernández

2015-01-01

Full Text Available Salt production in the Mixteca Alta is a traditional means of production from prehispanic period, which, despite the economic transformation processes in the colonial period, remained significant features of the traditional process, based on the documented similar models from other productive regions in Mexico. The salt in the novohispanic period was considered a major consumption economic asset due to its use in production processes for the production of new economic products that supported the economy of preindustrial societies (Terán, 2011, p. 71; Williams, 2008. Technology refers to the knowledges for solving human needs arising lifestyle of the cultural groups that develop them. The resources of the natural environment underpin the means of labor that man requires to perform its activities, including economic. The means of production and production processes are technological developments, which involve elements of tangible and intangible order. The study of work processes for salt extraction, are significantly related to the processes of technological evolution that man has developed for the use of natural resources. The economic activities of the primary sector are examples of how humans culturally and economically were inserted in the natural environment (Malpica, 2008, p. 59. This analysis presents a historiographical approach to the study of the processes and the technology required for the extraction of salt in the Mixteca Alta.

AGRICULTURA SOSTENIBLE EN ECOSISTEMAS DE ALTA MONTAÑA

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DIANA MARCELA RUIZ O

Full Text Available La agricultura como principal actividad del desarrollo económico rural en Colombia ha sido implementada con diferentes estrategias desde la época precolombina. Los ecosistemas de la alta montaña no han sido ajenos a esta realidad, y particularmente en las zonas de Páramo del Cauca, el intento por favorecer la prevalencia de un modelo altamente productivo e intensivo en el uso del suelo ha conllevado al detrimento de la diversidad socio-ecológica, la rápida expansión de la frontera agropecuaria en áreas estratégicas, la pérdida del conocimiento tradicional sobre el uso de la tierra y el bajo rendimiento de los cultivos que ha implicado mayor incorporación de fertilizantes al suelo amenazando estos sistemas vulnerables en la alta montaña. Sin embargo, es común encontrar en diferentes localidades paramunas caucanas comunidades indígenas y campesinas que reconocen la necesidad de cambiar los sistemas productivos que han venido empleando debido a la disminución de la fertilidad del suelo que limita la comercialización de sus productos y a la problemática ambiental asociada, en este sentido, el acompañamiento institucional en este proceso es vital para favorecer la implementación de procesos sostenibles de forma integral.

Altas habilidades/superdotação: mitos e dilemas docentes na indicação para o atendimento

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Sonia Maria Lourenço de Azevedo

Full Text Available O baixo quantitativo de indicação de alunos com altas habilidades/superdotação apontado pelos professores de um Município da periferia do Rio de Janeiro motivou a investigação das possíveis dificuldades encontradas pelos professores nesse processo. Os sujeitos desta pesquisa são 52 professores divididos em dois grupos: 26 professores que indicaram alunos para o programa de alunos com altas habilidades/ superdotação da Secretaria Municipal de Educação desse Município (grupo 1, e 26 professores que não indicaram alunos (grupo 2. Os fatores utilizados nesta pesquisa foram: (a perfil sociodemográfico dos respondentes; (b levantamento de possíveis elementos da representação social desse professor por meio dos termos indutores: altas habilidades/superdotação e educação especial; (c três dilemas baseados na teoria de julgamento moral e nos mitos referentes a altas habilidades/superdotação. conclui-se que, em ambos os grupos, há fortes indícios de que os mitos acerca das altas habilidades/superdotação influenciam a indicação/não indicação desses alunos, e que esses mitos devem ser discutidos junto aos professores de modo a facilitar a indicação

Efeitos do treinamento resistido sobre o perfil lipídico de indivíduos com síndrome metabólica

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R.A. Albarello

2017-09-01

Conclusão: Maiores concentrações de lipoproteína de alta densidade, a diminuição da circunferência do abdômen e menores níveis de ureia, bem como provocados pelo treinamento resistido na população em questão são reflexão de menor risco cardiovascular, indicando que o treinamento resistido pode ser benéfico.

Comportamento de cultivares de cafeeiro em diferentes densidades de plantio The behavior of coffee cultivars under different plant densities

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Edison Martins Paulo

2005-01-01

Full Text Available Avaliou-se em Adamantina, na Região da Alta Paulista, em São Paulo, entre maio de 1995 e junho de 2000, o crescimento e quatro produções de cafeeiros das cultivares de porte baixo Catuaí Amarelo IAC 47 e Obatã IAC 1669-20 de Coffea arabica L., submetidas às densidades de plantio de 2.500, 5.000, 7.519 e 10.000 plantas ha-1, com uma planta por cova. Estudou-se também a população de 2.500 plantas.ha-1 em covas com duas plantas com 2,0 m de distância na linha de plantio. Adotou-se o delineamento estatístico de blocos ao acaso com três repetições, com parcelas subdivididas, onde as parcelas foram as populações e as subparcelas, as cultivares. Os resultados permitiram inferir que, no período estudado, o aumento da densidade influenciou positivamente a altura e negativamente o diâmetro do caule e da base da copa dos cafeeiros, mas não a altura da inserção do primeiro ramo plagiotrópico a partir do nível do solo. O aumento da população de cafeeiros acarretou menor produção de café beneficiado por planta, mas concorreu para o aumento da produtividade no período de 1997 a 2000. O plantio de duas mudas de café por cova acarretou também diminuição do diâmetro do caule e da produção individual dos cafeeiros. Observou-se na cultivar Catuaí Amarelo IAC 47 maior diâmetro da base da copa e maior crescimento em altura, enquanto a cv. Obatã IAC 1669-20 evidenciou seu maior diâmetro do caule. As cultivares Catuaí Amarelo IAC 47 e Obatã IAC 1669-20 não diferiram entre si quanto à produção individual e à produtividade de café beneficiado no quadriênio (1997-2000.This experiment was developed at Adamantina, west region of the State of São Paulo, Brazil, during May of 1995 to June of 2000. The plant growth and productivity of two coffee cultivars Catuaí Amarelo IAC 47 and Obatã IAC 1669-20, were evaluated considering to plant densities of 2.500, 5.000, 7.519 and 10.000 plants ha-1. The density of 2500 also was

EFECTO DE LA DENSIDAD DE PLANTACIÓN EN LA RENTABILIDAD DE PLANTACIONES DE Eucalyptus globulus

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Emilio Guerra-Bugueño

2014-01-01

Full Text Available El estudio evaluó, económicamente, la respuesta de densidades de plantación y marcos de espaciamiento de Eucalyptus globulus establecido con fines pulpables. La técnica de Montecarlo se usó para examinar el efecto de las variaciones de precios y la tasa de descuento sobre la rentabilidad. El ensayo fue realizado en el Valle Central de la IX Región de Chile. Los tratamientos fueron: 1,000 árboles·ha-1(T1; 1,428 árboles·ha-1 (T2; 1,667 árboles·ha-1 (T3 y 2,000 árboles·ha-1 (T4. El volumen de producción de cada tratamiento se midió a la edad de cosecha (10 años y posteriormente se realizó un análisis financiero, para obtener la rentabilidad (valor actual neto [VAN], valor económico del suelo [VES] y tasa interna de retorno [TIR]. Los mayores valores de VAN se obtuvieron con el T1 (US$ 330·ha-1 y T4 (US$ 322·ha-1. Los pronósticos obtenidos para el VAN de T1 mostraron una probabilidad de ocurrencia de 73 %, resultando ser la opción menos riesgosa para la inversión. Los mayores rendimientos volumétricos (T4 y T3 no propician las mayores rentabilidades, pues el incremento de la densidad de plantación aumenta los costos por unidad de planta con relación al manejo de suelos, control de malezas y fertilización.

Chemical recycling of plastic wastes made from polyethylene (LDPE and HDPE) and polypropylene (PP)

International Nuclear Information System (INIS)

Achilias, D.S.; Roupakias, C.; Megalokonomos, P.; Lappas, A.A.; Antonakou, E.V.

2007-01-01

The recycling of either model polymers or waste products based on low-density polyethylene (LDPE), high-density polyethylene (HDPE) or polypropylene (PP) is examined using the dissolution/reprecipitation method, as well as pyrolysis. In the first technique, different solvents/non-solvents were examined at different weight percent amounts and temperatures using as raw material both model polymers and commercial products (packaging film, bags, pipes, food-retail outlets). The recovery of polymer in every case was greater than 90%. FT-IR spectra and tensile mechanical properties of the samples before and after recycling were measured. Furthermore, catalytic pyrolysis was carried out in a laboratory fixed bed reactor with an FCC catalyst using again model polymers and waste products as raw materials. Analysis of the derived gases and oils showed that pyrolysis gave a mainly aliphatic composition consisting of a series of hydrocarbons (alkanes and alkenes), with a great potential to be recycled back into the petrochemical industry as a feedstock for the production of new plastics or refined fuels

Chemical recycling of plastic wastes made from polyethylene (LDPE and HDPE) and polypropylene (PP).

Science.gov (United States)

Achilias, D S; Roupakias, C; Megalokonomos, P; Lappas, A A; Antonakou, Epsilon V

2007-11-19

The recycling of either model polymers or waste products based on low-density polyethylene (LDPE), high-density polyethylene (HDPE) or polypropylene (PP) is examined using the dissolution/reprecipitation method, as well as pyrolysis. In the first technique, different solvents/non-solvents were examined at different weight percent amounts and temperatures using as raw material both model polymers and commercial products (packaging film, bags, pipes, food-retail outlets). The recovery of polymer in every case was greater than 90%. FT-IR spectra and tensile mechanical properties of the samples before and after recycling were measured. Furthermore, catalytic pyrolysis was carried out in a laboratory fixed bed reactor with an FCC catalyst using again model polymers and waste products as raw materials. Analysis of the derived gases and oils showed that pyrolysis gave a mainly aliphatic composition consisting of a series of hydrocarbons (alkanes and alkenes), with a great potential to be recycled back into the petrochemical industry as a feedstock for the production of new plastics or refined fuels.

Evaluation of HDPE and LDPE degradation by fungus, implemented by statistical optimization

Science.gov (United States)

Ojha, Nupur; Pradhan, Neha; Singh, Surjit; Barla, Anil; Shrivastava, Anamika; Khatua, Pradip; Rai, Vivek; Bose, Sutapa

2017-01-01

Plastic in any form is a nuisance to the well-being of the environment. The ‘pestilence’ caused by it is mainly due to its non-degradable nature. With the industrial boom and the population explosion, the usage of plastic products has increased. A steady increase has been observed in the use of plastic products, and this has accelerated the pollution. Several attempts have been made to curb the problem at large by resorting to both chemical and biological methods. Chemical methods have only resulted in furthering the pollution by releasing toxic gases into the atmosphere; whereas; biological methods have been found to be eco-friendly however they are not cost effective. This paves the way for the current study where fungal isolates have been used to degrade polyethylene sheets (HDPE, LDPE). Two potential fungal strains, namely, Penicillium oxalicum NS4 (KU559906) and Penicillium chrysogenum NS10 (KU559907) had been isolated and identified to have plastic degrading abilities. Further, the growth medium for the strains was optimized with the help of RSM. The plastic sheets were subjected to treatment with microbial culture for 90 days. The extent of degradation was analyzed by, FE-SEM, AFM and FTIR. Morphological changes in the plastic sheet were determined.

Preparation and characterization of bagasse/HDPE composites using multi-walled carbon nanotubes.

Science.gov (United States)

Ashori, Alireza; Sheshmani, Shabnam; Farhani, Foad

2013-01-30

This article presents the preparation and characterization of bagasse/high density polyethylene (HDPE) composites. The effects of multi-walled carbon nanotubes (MWCNTs), as reinforcing agent, on the mechanical and physical properties were also investigated. In order to increase the interphase adhesion, maleic anhydride grafted polyethylene (MAPE) was added as a coupling agent to all the composites studied. In the sample preparation, MWCNTs and MAPE contents were used as variable factors. The morphology of the specimens was characterized using scanning electron microscopy (SEM) technique. The results of strength measurement indicated that when 1.5 wt% MWCNTs were added, tensile and flexural properties reached their maximum values. At high level of MWCNTs loading (3 or 4 wt%), increased population of MWCNTs lead to agglomeration and stress transfer gets blocked. The addition of MWCNTs filler slightly decreased the impact strength of composites. Both mechanical and physical properties were improved when 4 wt% MAPE was applied. SEM micrographs also showed that the surface roughness improved with increasing MAPE loading from 0 to 4 wt%. The improvement of physicomechanical properties of composites confirmed that MWCNTs have good reinforcement and the optimum synergistic effect of MWCNTs and MAPE was achieved at the combination of 1.5 and 4 wt%, respectively. Copyright © 2012 Elsevier Ltd. All rights reserved.

Evaluation of HDPE and LDPE degradation by fungus, implemented by statistical optimization.

Science.gov (United States)

Ojha, Nupur; Pradhan, Neha; Singh, Surjit; Barla, Anil; Shrivastava, Anamika; Khatua, Pradip; Rai, Vivek; Bose, Sutapa

2017-01-04

Plastic in any form is a nuisance to the well-being of the environment. The 'pestilence' caused by it is mainly due to its non-degradable nature. With the industrial boom and the population explosion, the usage of plastic products has increased. A steady increase has been observed in the use of plastic products, and this has accelerated the pollution. Several attempts have been made to curb the problem at large by resorting to both chemical and biological methods. Chemical methods have only resulted in furthering the pollution by releasing toxic gases into the atmosphere; whereas; biological methods have been found to be eco-friendly however they are not cost effective. This paves the way for the current study where fungal isolates have been used to degrade polyethylene sheets (HDPE, LDPE). Two potential fungal strains, namely, Penicillium oxalicum NS4 (KU559906) and Penicillium chrysogenum NS10 (KU559907) had been isolated and identified to have plastic degrading abilities. Further, the growth medium for the strains was optimized with the help of RSM. The plastic sheets were subjected to treatment with microbial culture for 90 days. The extent of degradation was analyzed by, FE-SEM, AFM and FTIR. Morphological changes in the plastic sheet were determined.

Creación de dinero y demanda por dinero durante la alta inflación boliviana de 1982-1985

OpenAIRE

Morales, Juan Antonio

2012-01-01

Las tasas de inflación mensual boliviana desde el segundo trimestre de 1984 asta el tercer trimestre de 1985 fueron las más altas del mundo en los últimos 35 años y solo comparables a aquellas sufridas en algunas naciones de Europa Central después de las dos guerras mundiales. Las altas tasas de crecimiento de los precios durante este periodo caracterizan un claro caso de hiperinflación. Aunque los síntomas más agudos se presentaron en el periodo mencionado, las altas tasas de inflación apare...

EFEITOS DO TRANSPORTE NO BEM-ESTAR E QUALIDADE DA CARNE DE BOVINOS / EFFECTS OF TRANSPORT ON WELFARE AND QUALITY OF BEEF CATTLE

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P. P. DINIZ

2011-11-01

Full Text Available Objetivou-se com esta revisão fazer um estudo bibliográfico sobre como o transporte rodoviário e o manejo inadequado dos animais na fazenda mostram-se importantes causas de perdas econômicas devido às lesões nas carcaças com consequente rejeição do sistema de inspeção durante o abate. O transporte rodoviário é o meio mais comum de condução de animais de corte para o abate. O transporte rodoviário, em condições desfavoráveis, pode provocar a morte dos animais ou conduzir a contusões, perda de peso e estresse dos animais. O aumento do estresse durante o transporte é proporcionado pelas condições desfavoráveis como privação de alimento e água, alta umidade, alta velocidade do ar e densidade de carga. O principal aspecto a ser considerado durante o transporte de bovinos, é o espaço ocupado por animal, ou seja, a densidade de carga, que pode ser classificada em alta (600 Kg/m², média (400 Kg/m² e baixa (200 Kg/m². Assim, o objetivo desta revisão bibliográfica é fazer um levantamento dos principais fatores durante o transporte dos bovinos que estão relacionados com as perdas na qualidade e rendimentos de carcaça. Palavras-chave: carcaça, lesões, transporte. 

Basic specific gravity and anatomy of Peltophorum dubium wood as a function of provenance and radial position. Densidade aparente e anatomia da madeira de Peltophorum dubium em função da procedência e posição radial.

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Israel Luiz de LIMA

2015-06-01

da madeira em comparação com as características externas mais sensíveis a estresses ambientais, como as folhas. Com base na literatura e em nossos resultados anteriores, a variação radial em P. dubium foi semelhante à encontrada em muitas espécies nativas, incluindo, por exemplo, aumento na densidade aparente, comprimento e espessura da parede das fibras, aumento no diâmetro e diminuição na frequência de vasos na direção da casca. Concluímos que P. dubium tem alta adaptabilidade em diferentes locais e que a consistência na qualidade de sua madeira pode ser mantida entre procedências, com implicações concomitantes, tanto para produção quanto para a utilização.

: Toward a conceptualization of a paracas urbanism in ánimas altas / ánimas bajas (Ica Valley)?

OpenAIRE

Bachir Bacha , Aïcha; Llanos Jacinto , Oscar Daniel

2015-01-01

International audience; Since 2009, within the framework of the Ánimas Altas Archaeological Program in Ica, Peru — under the direction of the au-thors — systematic excavations have been carried out in the Ánimas Altas/Ánimas Bajas archaeological complex, the center ofthe Paracas culture in the lower Ica valley. To date, the project has documented public-ceremonial architecture as well as domesticand production areas. Additionally, excavations have revealed evidence of pyramidal complexes cont...

Valor pronóstico de las fracciones lipídicas basales, en pacientes operados de revascularización miocárdica con circulación extracorpórea Prognostic value of basal lipid fractions in patients operated on of myocardial revascularization with extracorporeal circulation

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José Ramón Llanes Echevarría

2011-09-01

Full Text Available Se realizó un estudio observacional, longitudinal y prospectivo en 60 pacientes, durante el período de enero 2008-2009, con el objetivo de determinar el valor pronóstico de estas fracciones lipídicas basales y su relación con la ocurrencia de eventos clínicos adversos, en el posoperatorio de pacientes con indicación de revascularización miocárdica con circulación extracorpórea. Como resultados obtuvimos, que las concentraciones basales del colesterol total, los triglicéridos, y el colesterol asociado a las lipoproteínas de alta densidad, a las lipoproteínas de baja densidad y a las lipoproteínas de muy baja densidad, se modificaron durante el proceder quirúrgico y en la sala de recuperación. Además, se demostró una disminución significativa de las lipoproteínas de alta densidad y una tendencia de aumentar el nivel de colesterol, en el grupo de pacientes que manifestó eventos clínicos adversos, y se observó también, una estrecha asociación entre estos eventos y estas 2 variables lipídicas (pA prospective, longitudinal and observational study was conducted in 60 patients from January 2000-2009 to determine the prognostic value of these basal lipid fractions and its relation to occurrence of adverse clinical events in postoperative period of patients with an extracorporeal circulation myocardial revascularization indication. As result, the basal concentrations of total cholesterol, triglycerides and the cholesterol associated with high density lipoproteins (HDL were modified during the surgical procedure and in the recovery unit. Also, it was shown a significant decrease of HDL and a trend to increase the cholesterol level as well as a close association among these events and these lipid variables (p <0.05. We conclude that patients with an altered lipid profile basis are more liable to develop adverse clinical events in the immediate postoperative period of coronary surgery with extracorporeal circulation.

Diseño de decodificadores de altas prestaciones para código LDPC

OpenAIRE

Angarita Preciado, Fabian Enrique

2013-01-01

En esta tesis se han investigado los algoritmos de decodificación para códigos de comprobación de paridad de baja densidad (LDPC) y las arquitecturas para la implementación hardware de éstos. El trabajo realizado se centra en los algoritmos del tipo de intercambio de mensajes para códigos estructurados los cuales se incluyen en varios estándares de comunicaciones. Inicialmente se han evaluado las prestaciones de los algoritmos existentes Sum-product, Min-Sum y las principales variantes de...

Audiitor kaebas Alta Capitali arve pärast Läti kohtusse / Henrik Ilves

Index Scriptorium Estoniae

Ilves, Henrik

2008-01-01

Eesti Päevalehe andmetel kaebas rahvusvaheline audiitorfirma Ernst & Young Lätis kohtusse investeerimisfirma Alta Capital, kuna firma ei ole maksnud esitatud arvet. Nõude suuruseks on 4,69 miljonit krooni

The influence of sol on the behavior of melting and nonisothermal crystallization kinetic of radiation cross-linking HDPE

International Nuclear Information System (INIS)

Deng Pengyang; Xie Hongfeng; Deng Mingxiao; Zhong Xiaoguang

2000-01-01

By using DSC, the behavior of second melting and nonisothermal crystallization of pure gel pure sol and sol-gel blend of radiation crosslinking HDPE was studied. The authors found that, because of the existence of sol, there is notable difference between pure gel and pure sol or sol-gel blend. Under the same dose, the melting point and crystallization temperature of pure sol and sol-gel blend are higher than that of pure gel. At the same time, the authors also found that the Avrami exponent of original PE, pure sol and sol-gel blend is the similar to each other and different to that of pure gel, which means that the procedure of nucleation and growth of these samples is the same and also different to that of pure gel

Cinemómetro piezoeléctrico de alta exactitud (VUAE

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Jiménez Martínez, F. J.

2012-02-01

Full Text Available We have developed a portable computerized and low consumption, our system is called High Accuracy Piezoelectric Kinemometer measurement, herein VUAE. By the high accuracy obtained by VUAE it make able to use the VUAE to obtain references measurements of system for measuring Speeds in Vehicles. Therefore VUAE could be used how reference equipment to estimate the error of installed kinemometers. The VUAE was created with n (n≥2 pairs of ultrasonic transmitter-receiver, herein E-R_ult. The transmitters used in the n couples E-R_ult generate n ultrasonic barriers and receivers receive the echoes when the vehicle crosses the barriers. Digital processing of the echoes signals let us to obtain acceptable signals. Later, by mean of cross correlation technics is possible make a highly exact estimation of speed of the vehicle. The log of the moments of interception and the distance between each of the n ultrasounds allows for a highly exact estimation of speed of the vehicle. VUAE speed measurements were compared to a speed reference system based on piezoelectric cables.

Se ha desarrollado un sistema electrónico computerizado, portátil y de bajo consumo, denominado Medidor de Velocidad de Vehículos por Ultrasonidos de Alta Exactitud, VUAE. La alta exactitud de la medida conseguida en el VUAE hace que pueda servir de medida de referencia de la velocidad de un vehículo circulando en carretera. Por tanto el VUAE puede usarse como medida de referencia que permita estimar el error de los cinemómetros comerciales. El VUAE está compuesto por n (n≥2 parejas de emisores y receptores piezoeléctricos de ultrasonidos, denominados E-R_ult. Los emisores de las n parejas E-R_ult generan n barreras de ultrasonidos, y los receptores piezoeléctricos captan la señal de los ecos cuando el vehículo atraviesa las barreras. Estos ecos se procesan digitalmente para conseguir se

Defectos eritrocíticos y densidad de la parasitemia en pacientes con malaria por Plasmodium falciparum en Buenaventura, Colombia Erythrocyte defects and parasitemia density in patients with Plasmodium falciparum malaria in Buenaventura, Colombia

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Martha Moyano

2005-07-01

Full Text Available OBJETIVOS: Determinar la prevalencia de algunos defectos eritrocíticos y evaluar su relación con la densidad de la parasitemia en personas con diagnóstico de malaria (paludismo por Plasmodium falciparum en una población del Pacífico colombiano. MÉTODOS: Se realizó un estudio de prevalencia en 242 personas con malaria por P. falciparum que consultaron al Programa de Enfermedades Tropicales en la ciudad de Buenaventura, Colombia. Se midieron los niveles de parasitemia y se determinó la presencia de defectos eritrocíticos congénitos (deficiencia de glucosa-6-fosfato deshidrogenasa [G6PD] y presencia de hemoglobinas anormales y de talasemias y de otros factores potencialmente relacionados con los niveles de parasitemia. RESULTADOS: La prevalencia obtenida de defectos eritrocíticos fue de 26,4% (IC95% 21,0 a 32,5, similar a la hallada en estudios realizados antes en la misma zona. En los modelos de regresión múltiple, las personas con drepanocitosis o deficiencia total de la G6PD presentaron una menor densidad de parasitemia que las personas sin defecto, y el riesgo de parasitemias altas fue menor en estas personas después de ajustes respecto a otras variables de interés (razón de posibilidades [odds ratio, RP]: 0,30 y 0,72, respectivamente. CONCLUSIONES: Los resultados confirman una alta prevalencia de defectos eritrocíticos en el Pacífico colombiano, en una población con características étnicas similares a las de algunas poblaciones del África Occidental, y aportan información en favor de la existencia de resistencia innata a la malaria en personas portadoras de hemoglobina AS o con deficiencia de la G6PD.OBJECTIVES: To determine the prevalence of some erythrocyte defects and to evaluate the relation that that has with parasitemia density in individuals diagnosed with Plasmodium falciparum malaria in a population in the Pacific coastal region of Colombia. METHODS: This prevalence study was carried out with 242 persons with P

Resposta de híbridos de milho irrigado à densidade de plantas em três épocas de semeadura Response of irrigated corn hybrids to plant density in three sowing dates

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Paulo Regis Ferreira da Silva

1999-04-01

Full Text Available A determinação da densidade ótima de semeadura do milho, além de ser influenciada pelas características dos híbridos, pelo nível de fertilidade do solo e pela disponibilidade hídrica, pode também variar de acordo com a época da semeadura, uma vez que ela afeta o crescimento e desenvolvimento da planta. Com o objetivo de determinar a densidade ótima de planta em híbridos de milho com elevado potencial de rendimento de grãos, em três épocas de semeadura, com relação a rendimento de grãos, componentes do rendimento e outras características agronômicas, foram feitos quatro experimentos na região fisiográfica da Depressão Central do Rio Grande do Sul, município de Eldorado do Sul, com suplementação hídrica por aspersão. Os tratamentos constaram de quatro híbridos (Pioneer 3063, Pioneer 3207, XL 212 e Cargill 901, quatro densidades de plantas (50, 70, 90 e 110.000 pl/ha e de três épocas de semeadura (agosto, outubro e dezembro. Não há resposta à densidade de plantas dos híbridos de milho testados nas épocas de semeadura de agosto e dezembro. O aumento na densidade de plantas somente foi vantajosa na semeadura de outubro, quando se obtiveram maiores rendimentos de grãos na densidade de 70.000 pl/ha, independentemente do híbrido avaliado, nas duas estações de crescimento.Plant density response of corn besides influenced by hybrids traits, soil fertility level and water availability, could also vary with sowing date, since it affects plant growth and development. With the objective of determining the most adequate plant density of corn hybrids with high potential grain yields, in three sowing dates, in relation to grain yields, yield components and other agronomic traits, four experiments were conducted in the state of Rio Grande do Sul, Brazil, with complementary irrigation. The treatments were composed by four hybrids (Pioneer 3063, Pioneer 3207, XL 212 and Cargill 901, four plant densities (50, 70, 90 and 110

Alta precoz postparto. Evaluación de las complicaciones maternas y neonatales; repercusión en la ansiedad materna

OpenAIRE

Goyeneche Lasaga, Leire

2014-01-01

246 p. Ensayo clínico controlado aleatorizado simple ciego, sin medicamento, fase IV, unicéntrico donde se comparó el alta precoz a las 24 horas del parto y una visita hospitalaria a las 48h del alta, con el alta habitual a las 48-72 horas. Para ello se incluyeron un total de 416 mujeres sanas y mayores de edad que habían dado a luz por vía vaginal a un RN único, sano y a término entre el 1 de Octubre del 2012 y el 19 de Septiembre del 2013 en el Hospital Universitario Donostia; 208 fueron...

La evaluación psicopedagógica del alumnado con altas capacidades

OpenAIRE

Grau Rubio, Claudia

2012-01-01

Se describen los instrumentos de evaluación psicopedagógica aplicables al alumnado con altas capacidades. Instrumentos referidos al alumno, al contexto escolar, a las variables socio-familiares y la determinación de las necesidades educativas especiales.

Densidade do solo, atributos químicos e sistema radicular do milho afetados pelo pastejo e manejo do solo

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V. R. Silva

2000-03-01

Full Text Available A integração lavoura-pecuária é uma alternativa de renda dos produtores no sul do Brasil. Entretanto, o pisoteio animal e, ou, o preparo de solo podem compactá-lo, prejudicando o crescimento radicular e a produtividade das plantas. Estudaram-se os efeitos do pisoteio animal em regime de pastejo contínuo durante o inverno/primavera e do impacto do plantio direto e do preparo convencional de solo no estado de compactação, atributos químicos e distribuição radicular. Em Podzólico Vermelho-Amarelo de textura superficial franca, foi implantada uma pastagem de estação fria composta por aveia (Avena strigosa Schreb e azevém (Lolium multiflorum L.. A carga animal variou conforme o crescimento da pastagem. Em dezembro de 1996, foi implantada a cultura do milho (Zea mays L. para a produção de silagem, usando os seguintes tratamentos: plantio direto na área não pastejada, plantio direto após o pastejo, preparo convencional de solo na área não pastejada e preparo convencional de solo após pastejo. As avaliações apresentadas neste estudo são referentes ao terceiro ano de cultivo, no qual houve um período de pastejo de 107 dias. Aos 45 dias da emergência do milho, foram abertas trincheiras (100 x 40 cm para visualizar a distribuição do sistema radicular e coletar amostras de solo, a cada 5 cm, para caracterização química e determinação da densidade do solo e de raízes. Ao longo do perfil (0-40 cm, o desenho da distribuição de raízes indicou maior quantidade de raízes no preparo convencional de solo, concordando com os resultados de densidade de raízes. O pisoteio animal não teve efeito sobre as características físicas, possivelmente pelo fato de o resíduo da pastagem permanecer próximo a 1,0 Mg ha-1 de matéria seca. A densidade do solo no plantio direto, na camada de 5-10 cm, foi de 1,41 Mg m-3, tanto na área pastejada como na não pastejada. No preparo convencional de solo, esses valores foram de 1,15 Mg m-3

Densidades de plantio e doses de biofertilizante na produção de capim-limão Density and biofertilizer levels for lemon grass production

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Arie F Blank

2007-09-01

Full Text Available O objetivo do trabalho foi avaliar o efeito de densidades de plantio e doses de biofertilizante comercial na produção de capim-limão (Cymbopogon citratus (D.C. Stapf. O experimento foi implantado em parcelas subdivididas com três repetições, colocando-se nas parcelas as densidades de plantio (33.333, 49.382, 55.555 e 111.111 plantas ha-1 e nas subparcelas as doses de biofertilizante (0; 20; 40 e 60 t ha-1. Foram realizadas nove colheitas em intervalos de 42 dias. Avaliou-se a sobrevivência, a altura de planta, o número de perfilhos por touceira, a massa seca por touceira e da parte aérea, o teor e o rendimento de óleo essencial. O teor de óleo essencial não foi influenciado pelas densidades de plantio e doses de biofertilizante. A densidade crescente resultou em regressões lineares crescentes para o rendimento de óleo essencial e a massa seca da parte aérea e em uma regressão linear decrescente para a massa seca por touceira. A dose de biofertilizante resultou em regressões lineares crescentes para o rendimento de óleo essencial e a massa seca por touceira e da parte aérea. A densidade de 111.111 plantas ha-1 (0,30 x 0,30 m e a dose de biofertilizante de 60 t ha-1 no primeiro ano de cultivo poderão ser recomendados para produção do capim-limão.The aim of this work was to evaluate the plant density and biofertilizer levels on lemon grass (Cymbopogom citratus (D.C. Stapf. The experiment was installed in split plot design with three replications, having plant density as plots (33,333; 49,382; 55,555 and 111,111 plants ha-1 and biofertilizer doses as sub plots (0; 20; 40; 60 t ha-1 year-1. Nine cuttings were realized using an interval of 42 days between cuttings. We evaluated survival, plant height, number of tillers per plant, dry weight per plant and of biomass yield, essential oil content and yield. The essential oil content was not influenced by the plant densities and biofertilizer doses. The crescent density resulted in

Chapter 2 Western dominance Piedra Alta terrane

International Nuclear Information System (INIS)

2005-01-01

Piedra Alta Stone includes: geo chemical and geochronology of the granitic complex is located in the SW portion of the crystalline basement of Uruguay. It consists of four thin metamorphic belts separated by a granitic complex - gneissic - migmatítico (CGG) and associated with an important granite, granodiorite, basic or ultrabasic magmatic. Belts north to south are called Arroyo Grande Andresito by renowned Bossi et al. (2000); San Jose (Preciozzi et al., 1991), San Juan (Preciozzi et al, 2005) and Montevideo (Bossi et al., 1993) Pando by renowned Bossi et al. (2000). They are composed of volcano-sedimentary units of different degrees of metamorphism and a set of associated intrusions

Decision 2010-021 : TransAlta Wind Ardenville wind plant and substation : application no. 1604970, proceeding ID 260

International Nuclear Information System (INIS)

2010-01-01

TransAlta Wind, a wholly owned subsidiary of TransAlta Corporation, filed an application in April 2009 to construct and operate the Ardenville wind farm and substation in Alberta. The wind farm consists of 23 wind turbines, each rated at 3 MW, for a total installed capacity of 69 MW. The wind farm would be connected to the Alberta Interconnected Electric System at the substation. TransAlta anticipates that a new 138-kV transmission line will be required and has contacted the transmission facilities for the future applications. The Alberta Utilities Commission issued a notice to all interested parties and landholders within 2 km of the proposed wind farm. Two residents raised concerns regarding the use of fossil fuels and alternative fuels, ecological impacts and aesthetic impacts of wind farms and land values. Upon review of information, the Commission was satisfied that approval of the application was in the public interest and that the wind farm complies with all regulatory requirements, including sound levels. Pursuant to sections 11, 14 and 15 of the Hydro and Electric Energy Act, the Commission approved the application and granted approval to TransAlta Wind to construct and operate the Ardenville wind power plant and substation.

Situación actual de primates en bosques de alta perturbación del nororiente de la Amazonía peruana

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Rolando Aquino

2015-06-01

Full Text Available En el nororiente peruano, el área comprendida entre la cuenca baja del río Tigre y sub cuenca del río Nanay es una de las más impactadas por las actividades del hombre. Con excepción del río Itaya y bajo Nanay, para el resto del área no existe información acerca de los primates que habitan, ni de las amenazas para sus poblaciones; motivo por el cual nos propusimos a la conducción de este estudio. De Febrero a Julio del 2013 fueron llevados a cabo censos por transecto y entrevistas a cazadores. Durante el recorrido de 1 218 km fueron registrados 373 grupos pertenecientes a 10 especies, siendo los más comunes Saguinus lagonotus (104 grupos y Lagothrix poeppigii (61 grupos. Grupos más pequeños fueron para Alouatta seniculus (3–4 individuos y Callicebus discolor (2–4 individuos y la más grande para Saimiri macrodon. La densidad poblacional más alta fue para S. macrodon (30,4 individuos/km2 seguido de S. lagonotus (25,8 individuos/km2 y la más baja para A. seniculus (1,4 individuos/km2 y C. discolor (2,3 individuos/km2. Durante los censos no observamos ni escuchamos vocalizaciones de Ateles belzebuth, en tanto que A. seniculus  estuvo ausente en el Alto Itaya. Entre las actividades, la caza y deforestación con diversos fines son las principales amenazas, por lo tanto, serían las responsables para la extinción local de A. belzebuth y escasa población de A. seniculus y C. discolor.

Physical, mechanical and neutron shielding properties of h-BN/Gd2O3/HDPE ternary nanocomposites

Science.gov (United States)

İrim, Ş. Gözde; Wis, Abdulmounem Alchekh; Keskin, M. Aker; Baykara, Oktay; Ozkoc, Guralp; Avcı, Ahmet; Doğru, Mahmut; Karakoç, Mesut

2018-03-01

In order to prepare an effective neutron shielding material, not only neutron but also gamma absorption must be taken into account. In this research, a polymer nanocomposite based novel type of multifunctional neutron shielding material is designed and fabricated. For this purpose, high density polyethylene (HDPE) was compounded with different amounts of hexagonal boron nitride (h-BN) and Gd2O3 nanoparticles having average particle size of 100 nm using melt-compounding technique. The mechanical, thermal and morphological properties of nanocomposites were investigated. As filler content increased, the absorption of both neutron and gamma fluxes increased despite fluctuating neutron absorption curves. Adding h-BN and Gd2O3 nano particles had a significant influence on both neutron and gamma attenuation properties (Σ, cm-1 and μ/ρ, cm-2/g) of ternary shields and they show an enhancement of 200-280%, 14-52% for neutron and gamma radiations, respectively, in shielding performance.

Vulnerabilidad en la cuenca alta del rio Lerma

OpenAIRE

Cedeño Valdiviezo, Alberto; Torres Lima, Pablo

2013-01-01

La subcuenca Alta del Río Lerma en el Estado de México, importante abastecedor de agua para la Ciudad de México, ha estado expuesta a una fuerte contaminación en los últimos años, misma que ha tenido como consecuencia el Cambio Climático y los consecuentes problemas de salud pública que se están manifestando de diferentes maneras. No obstante, el Estado Mexicano insiste en seguir apoyando a empresas trasnacionales asociadas al cultivo de transgénicos, producción de plaguicidas, pesticidas y P...

Efeito da Densidade de Criação e do Sexo Sobre o Empenamento, Incidência de Lesões na Carcaça e Qualidade da Carne de Peito de Frangos de Corte

OpenAIRE

Garcia RG; Mendes AA; Garcia EA; Nääs IA; Moreira J; Almeida ICL; Takita TS

2002-01-01

O experimento foi conduzido nas instalações experimentais da Faculdade de Medicina Veterinária e Zootecnia - UNESP, Campus de Botucatu, SP, Brasil, com o objetivo de avaliar o efeito da densidade de criação e do sexo sobre o empenamento, incidência de lesões na carcaça e a qualidade de carne de peito de frangos de corte. Foram utilizados 1950 pintos de corte sexados, da linhagem Ross, distribuídos em um delineamento inteiramente casualizado, com esquema fatorial com 3 densidades (10, 13 e 16 ...

DENSIDAD CRÍTICA DE Meloidogyne exigua EN PLANTAS DE ALMÁCIGO DE CAFÉ VARIEDAD CATURRA

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Mainor Rojas

2013-01-01

Full Text Available El objetivo del estudio fue evaluar el efecto de densidad creciente de Meloidogyne exigua sobre el desarrollo de plantas de almácigo. Se trasplantaron plántulas de café variedad caturra a bolsas de polietileno con 1335 cm3 de sustrato desinfectado, para establecer un ensayo con diseño de bloques completos al azar, con 8 repeticiones. Los tratamientos aplicados consistieron de poblaciones iniciales (Pi de 0; 0,125; 0,25; 0,5; 1; 2; 4; 8; 16; 32 y 64 huevos+J2/ cm3 de sustrato, aplicadas un mes después del trasplante. El modelo y=m+(1-m ZP-T aplicado 234 días después del trasplante para la altura, diámetro, número de nudos y peso fresco aéreo, indicó que el límite de tolerancia (T fue de 0,66; 0,06; 0,13 y 0,88 huevos+J2/cm3, respectivamente; la producción mínima relativa (m fue de 0,79; 0,79; 0,33 y 0,54 respectivamente, a Pi iguales o mayores a 64 huevos+J2/cm3. El índice de agallas alcanzó el máximo a partir de una Pi de 2; el pico máximo de nematodos en el suelo y las raíces se alcanzó con Pi entre 2 y 4; mientras la tasa máxima de reproducción fue de 114 con Pi de 0,125. Se concluyó que la densidad crítica fue cercana a cero huevos/cm3 de sustrato como población inicial, y que el almácigo se debe desarrollar libre de nematodos, ya que aún con Pi bajas se puede alcanzar la máxima población en corto tiempo.

Densidade de estocagem no desempenho de larvas de tilápia-do-Nilo (Oreochromis niloticus L., durante a reversão sexual Stocking density effect on Nile tilapia (Oreochromis niloticus L. fry performance during sex reversal

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Luís Eduardo Ferrari Sanches

1999-11-01

Full Text Available Para estudar os efeitos da densidade de estocagem no desempenho de larvas de tilápia-do-Nilo, Oreochromis niloticus, durante a fase de reversão sexual em águas verdes, foram estocadas 1.500 larvas com peso médio de 12,41mg e comprimento total médio de 9,38mm em tanques-rede de 12,5 litros, nas densidades de 2, 4, 6, 8 e 10 larvas/litro, em delineamento totalmente aleatório com 4 repetições. Essas foram tratadas com ração comercial fina com 43% de PB, contendo 60mg de metiltestosterona/kg, 6 vezes por dia, durante 28 dias. O aumento da densidade resultou em menor peso e comprimento médios finais, definidos por modelos de regressão. O efeito da densidade sobre a diminuição do crescimento se evidenciou a partir da terceira semana de criação. A biomassa total e a conversão alimentar mostraram-se incrementadas com o aumento da densidade. A sobrevivência, o fator de condição e o coeficiente de variação foram independentes da densidade. Conclui-se que 2 larvas/litro devem ser usadas, quando se objetiva produção de alevinos maiores; mas densidades maiores podem ser utilizadas, obtendo-se alevinos menores, porém incrementando a biomassa total.To study the effects of stocking density on the performance of newborn fries of Nile tilapia Oreochromis niloticus, during sex reversal stage in green waters, 1500 fries were stocked with 12.41mg of average weight and 9.38mm of total average length in hapas of 12,5 litres, at densities of 2, 4, 6, 8 and 10 fries/litre, in a completely randomized design with 4 replications. They were fed with a fine commercial diet containing 43% CP, and 60mg of methyltestosterone/kg, six times a day, during 28 days. The density increase resulted in lower final average weight and length defined by regression models. The effect of density on the growth decrease started to be significative on the second week of rearing, while the total biomass and feed conversion were increased with the density increase

Sobrepeso, obesidad y dislipidemias en población universitaria del noreste de México Sobrepeso, obesidade e dislipidemias em população universitária do nordeste de México Overweight, obesity, and dyslipidemias at a mexican northeastern university population

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Martha Magallanes Monrreal

2010-03-01

Full Text Available Objetivo: determinar la prevalencia de sobrepeso, obesidad y dislipidemias en la población universitaria del noreste de México. Metodología: estudio descriptivo de corte transversal. Se hizo muestreo aleatorio estratificado con asignación proporcional de 292 personas. Se tomaron muestras sanguíneas para determinación del colesterol total, las lipoproteínas de baja y alta densidad, se midieron el peso y la talla para cálculo de índice de masa corporal (IMC. Resultados: se encontró una prevalencia total de 31,2% de sobrepeso (45.8% en hombres y 22.4% en mujeres y 15.1% de obesidad. La prevalencia global de hipercolesterolemia fue de 23.6% (31.4% en hombres y 18.4% en mujeres, y mayor en trabajadores manuales y administrativos (53.8% y 52.8% respectivamente. Las personas IMC por encima de lo normal tienen 2.55 veces el riesgo de dislipidemias, comparadas con las que tienen un peso normal (IC95:1.46-4.46. Los análisis multivariados mostraron diferencias significativas entre dos de los grupos comparados para las variables: colesterol total, lipoproteínas de alta densidad y triglicéridos; finalmente, el análisis Post Hoc de Tuckey mostró diferencias significativas entre el peso normal y el sobrepeso para colesterol total y las lipoproteínas de alta y baja densidad. Conclusión:hay una mayor prevalencia de obesidad en hombres que en mujeres. La asociación entre la obesidad y el colesterol total sugiere un mayor riesgo de enfermedad cardiovascular .Objetivo: determinar a prevalência de sobrepeso, obesidade e dislipidemias em população universitária do nordeste de México. Metodologia: estudo descritivo de corte transversal fezse amostragem aleatória estratificado com atribuição proporcional de 292 pessoas. Tomaramse mostras sanguíneas para determinação de colesterol total, lipoproteínas de baixa e alta densidade tomarameo peso e a talha para cálculo de índice de massa corporal (IMC. Resultados: encontrouse uma preval

Efeito da densidade de estocagem no cultivo de tainha, Mugil platanus (Günther, 1880 em laboratório Effect of stocking density on laboratory rearing of mullet fingerlings, Mugil platanus (Günther, 1880

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Marcelo Borges Tesser

2001-05-01

Full Text Available Estudou-se o efeito da densidade de estocagem sobre a produção de alevinos de Mugil platanus em laboratório. Foram testadas cinco densidades de estocagem em duplicata: 1, 3, 5, 10 e 15 tainhas/L. Os peixes foram alimentados duas vezes ao dia, sendo oferecido alimento na proporção de 10% do peso vivo de cada tanque. O melhor crescimento foi observado para os animais cultivados na menor densidade de estocagem (1 alevino/L. Observaram-se neste tratamento a melhor qualidade de água e a maior sobrevivência. Por outro lado, o maior número de animais foi produzido na densidade de 10 alevinos/L; entretanto, isto foi obtido às custas de uma menor qualidade da água, que se refletiu em uma redução no crescimento e na sobrevivência. No caso de produção comercial, os alevinos de M. platanus poderiam ser cultivados em uma densidade de estocagem entre 3 e 5 alevinos/L; contudo, a taxa de troca de água deveria ser mais elevada, para manter a concentração de amônia mais baixa do que aquela observada neste trabalhoThe effect of stocking density on production of Mugil platanus fingerlings in laboratory was analyzed. Five stocking densities were evaluated: 1, 3, 5, 10 and 15 mullet/L. After 28 days, the highest growth rate was reported for animals reared at the lowest stocking density (1 mullet/L. Survival rate and water quality were also higher at the lowest stocking density. Although more fingerlings were produced at 10 mullet/L, greater number of animals decreased the water quality, which was reflected in their reduced growth and survival rates. M. platanus fingerlings should be reared in commercial production at intermediate stocking densities (3-5 mullet/L but higher water exchange rates are recommended for lower ammonia concentration

Las nominaciones de los profesores en la identificación de alumnos de alta capacidad intelectual

OpenAIRE

Tourón, J. (Javier); Repáraz, C. (Charo); Peralta, F. (Feli)

2006-01-01

La capacidad de los profesores para identificar, a través de sus nominaciones, a los alumnos de alta capacidad intelectual en la Clase regular, es uno de los aspectos más controvertidos en la literatura de investigación. Mientras unos trabajos señalan la adecuación y conveniencia de las mismas, otros estudios ponen de manifiesto su falta de consitencia. En este estudio analizamos las nominaciones de los profesores en un proceso de identificación de alumnos de alta capacidad intelectual ...

Efecto de la densidad de semillas en la germinación de Isolatocereus dumortieri y Myrtillocactus geometrizans, cactáceas columnares endémicas de México Effect of seed density on germination of Isolatocereus dumortieri and Myrtillocactus geometrizans, endemic columnar cacti species from Mexico

Directory of Open Access Journals (Sweden)

Joel Flores

2009-04-01

Full Text Available Se evaluó el efecto de la densidad de semillas en la germinación de 2 cactáceas columnares: Isolatocereus dumortieri y Myrtillocactus geometrizans. Se utilizaron 5 tratamientos de densidad de semillas (1, 5, 10, 20 y 50 semillas. Isolatocereus dumortieri mostró menor porcentaje de germinación con el aumento de la densidad, mientras que la germinación de M. geometrizans no fue afectada por la densidad de semillas. Estos resultados sugieren que las plántulas de I. dumortieri podrían competir por recursos.The effect of seed density on the germination of 2 columnar cactus species (Isolatocereus dumortieri and Myrtillocactus geometrizans was evaluated using 5 seed density treatments (1, 5, 10, 20 and 50 seeds. Isolatocereus dumortieri had a lower germination percentage with increasing seed density; germination of M. geometrizans was not affected by seed density. These results suggest that I. dumortieri seedlings might compete for resources with siblings.

Conciliación de la medicación al alta hospitalaria en farmacia comunitaria: a propósito de un caso

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Molinero A

2017-09-01

Full Text Available Mujer de 86 años (itinerante entre dos comunidades autónomas con fibrilación auricular (FA persistente y fibrilación ventricular (FV controlada con anticoagulación oral, distimia, desorden de ansiedad, temblor esencial e insuficiencia venosa crónica que acude a la farmacia comunitaria (FC después de haber acudido a la consulta de su médico de atención primaria (MAP y que ha sido diagnosticada al alta hospitalaria (en la otra comunidad autónoma de ictus isquémico parietal derecho cardioembólico. No se ha realizado conciliación al alta y al dispensar las recetas del MAP se detecta que hay algunas duplicidades, faltan medicamentos prescritos en el informe de alta y sobran otros según lo que aparece en el informe al alta

微胶囊化阻燃剂对HDPE阻燃性能的影响%Effect of Microencapsulated Flame Retardant on Flame Retardancy of HDPE

Institute of Scientific and Technical Information of China (English)

陶圣熹; 夏艳平; 章诚; 曹峥; 陶国良

2017-01-01

以环氧树脂为囊材,阻燃剂二乙基次磷酸铝(ADP)和聚磷酸铵(APP)为芯材,制备了具有核壳结构的ADP微胶囊和APP微胶囊,并考察了其对高密度聚乙烯(HDPE)的阻燃性能.结果表明,当ADP微胶囊和APP微胶囊的总添加量为质量分数20%,复配质量比为2:1时,对HDPE的阻燃效果好,垂直燃烧达到V-0级,极限氧指数为32%,热失重残炭率为16.8%,拉伸强度达到21.6 M Pa.%Aluminum diethylphosphinate ( ADP ) microcapsules and ammonium polyphosphate (APP) microcapsules are prepared ,in which the epoxy resin is the shell , ADP and APP are the core .The effects of ADP and APP microcapsules on flame retarclancy of HDPE were studied . The results show that the total mass fraction of ADP microcap-sules and APP microcapsules is 20% with the ratio of 2 to 1 . The vertical burning is V-0 ,and the limit oxygen index is 32% . The carbon residue rate in the thermogravimetric (TG) test is 16 .8% . The maximum tensile strength is 21 .6 MPa ,and the material has the best flame retardant property .