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In the following work, synthesized polyethylene nanocomposites combined with a metallocene zirconium catalyst (PEZr) with 1 and 3 % multi-walled carbon nanotubes (MWCNT) were prepared. Maleic anhydride functionalized polyethylene nanocomposites (PEZr-g-MAH) and 4-aminopyridine functionalized polyethylene (PEZr-g-MAH / 4ampy) with 1 % NTsC were also prepared. All nanocomposites were characterized by: Infrared spectroscopy (FTIR), Differential Scanning Calorimetry (DSC); Self-nucleation (SN) and Thermal Fractionation by Successive Self-nucleation and annealing (SSA) experiments. The FTIR spectrum of the PEZr-g-MAH/1 %NTsC nanocomposite showed displacement of some absorption bands that increased a higher wave of numbers and that could occurred due to the interaction between the MWCNT and the carbonyl group of the anhydride and acid function of functionalized PE; while, in the PEZr-g-MAH / 4Ampy /1% NTsC nanocomposite, the intensive increment of the bands at 1097 and 1019 cm-1 was visualized. Non-isothermal DSC scans demonstrated the property of nanotubes to act as nucleating agents on the matrix of all the polymers studied. The study by SSA, together with the evaluation of the melting peaks using the software Peakfit 4.12, indicates that a redistribution of the lamellar thicknesses of the fraction with the highest melting temperature, speculating that it is possible the interactions of the π-π type between the pairs of free electrons of the pyridine ring of 4-Ampy and the electron cloud of MWCNTs. [ABSTRACT FROM AUTHOR]

Ahuyama (Cucurbita moschata) is recognized by its nutritional value, as it is composed of vitamin A, carbohydrates, phosphorus and minerals. Also, for its content of 45 % of total carotenoids; 66 % of β-carotene; 33 % of α-carotene, and 44 % of lutein. However, its high amount of water, about 90%, is conducive to bacterial and/or fungal growth reducing its useful life. Present study evaluated every three days, over a total of 12, three repetitions and three replications of freshly cut green bolus squash variety. Physicochemical attributes like weight, color, firmness, and respiration rate were observed, as well as those microscopic (MOAR and MET); bromatological, and microbiological characteristics to 4 different treatments as follow: SN (control sample); CV (Vinyl wrap); CR (coated with cassava starch and 1 % thyme essential oil); and CB: (binary system with natural source coating and Vinyl wrap) under environmental conditions of 19 °C temperature and 77,75 % average humidity. Vinyl wrap treatment exhibited lower weight, firmness loss, fewer respiration rate loss, and had better color stability. Control and coated samples showed higher sugar and moisture content but lower ash and protein. Additionally, samples with coated and uncoated stretch film registered minor fungal growth. Fresh cut squash could be properly preserved through the use of low-density polyethylene films (vinyl wrap), allowing to effectively delay the course of quality loss because of handling operations. [ABSTRACT FROM AUTHOR]

Introduction: In primary hip replacement, different materials are used for bearing surfaces. In our medium metal or ceramic heads with highly crossed-linked polyethylene (PA) are the most used. These combinations have good results, but it is not clear which is clinically superior. The objective of this study is to determine whether there is any clinically significant difference based on a systematic review of the literature and national registries of arthroplasty. Material and methods: We conduct a systematic review of the literature and national registries of arthroplasty and we were looking for studies comparing bearing surfaces: ceramic-highly cross-linked polyethylene (CP) and metal-highly cross-linked polyethylene (MP); describing the revision rate according to the surface type with a minimum 10-year follow-up. The outcome evaluated was: review rate for any cause depending on surface type. Results: Two out of fifteen national registries were included. The Australian registry shows a difference in the 15-year revision rate: CP: 6.3 (IC 5.8, 6.7) vs MP: 5.1 (IC 4.6, 5.7). The New Zealand registry shows no differences in revision rate/100 components/year: CP 0.54 (0.48-0.61) vs MP 0.61 (0.57-0.66). We do not find clinical studies with inclusion criteria that answer the research question. Conclusion: The results of this review show a high survival rate with the use of highly cross-linked polyethylene, the results are similar when using ceramic or metal heads. [ABSTRACT FROM AUTHOR]

Copyright of Terra Latinoamericana is the property of Sociedad Mexicana de la Ciencia del Suelo A.C. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The plastic bag used in the packaging of mozzarella cheese was characterized, for which the quality of the bag was evaluated through its identification by the method of solubility in organic and inorganic solvents, the quality of sealing by the colorful solution method, the determination of the speed of transmission to water vapor by the method gravimetric, dimensions and thickness. The results of the functional length and width presented average values of 396 mm and 374 mm respectively, the material proved to be made up of two flexible layers with a total thickness of 67.17 μm; an inner layer of polyethylene with a thickness of 47 μm and an outer layer of polyester with a thickness of 21 μm. The transmission speed to water vapor of the container was 2.33 g/m2d. [ABSTRACT FROM AUTHOR]

The polymer crystallization of the melt state occurs in the form of crystalline aggregates, known as spherulites. Polarized Light Microscopy (PLM) can be applied to the characterization of high density polyethylene (HDPE) grafting with maleic anhydride (HDPE-g-MAH), monitoring the spherulitic morphology before and after being chemically modified. The aim of the work was to characterize HDPE-g-MAH by PLM, Differential Scanning Calorimetry (DSC), Fourier Transform Infrared (FTIR) and calculate the grafting degree. With this purpose, national HDPE was placed in a three-necked flask with maleic anhydride (MAH) using o-dichlorobenzene as solvent and DBPH as initiator, at reflux for 67 minutes, at a temperature of 150 °C. From the product purified, films of HDPE and HDPE-g-MAH were obtained and analyzed. The results show that MAH was incorporated into amorphous zones of HDPE, with maleic acid units, indicating that the ring of maleic anhydride was hydrolyzed. In addition, was obtained a grafting degree of 2,42% molar. [ABSTRACT FROM AUTHOR]

In this work the influence of two semiconductor layers Ethyl Vinyl Acetate (EVA) and carbon black on the formation and propagation of space charge in contact with the low density polyethylene (LDPE) at high electric field (100 kV/ mm) was studied. These layers are used as internal and external contacts with cross-linked polyethylene (XLPE) MV cables forming interfaces where charge accumulates. Same chemical composition are used, the ion charge packets is attenuated and delay the propagation time through the sample volume of LDPE. [ABSTRACT FROM AUTHOR]

Copyright of Agro Productividad is the property of Colegio de Postgraduados and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

El objetivo principal de este trabajo fue estudiar el efecto de la temperatura y tiempo de calentamiento y tipo de plástico reciclado utilizado en la elaboración de ladrillos, sobre su resistencia a la compresión, módulo de elasticidad, densidad y absorción de agua. Se utilizaron dos tipos de plástico: polipropileno y polietileno de alta densidad, y temperaturas de entre 150 y 200 °C y tiempos entre 120 y 180 min. Las características fisicoquímicas de los ladrillos se analizaron en teniendo en cuenta las normas ASTM D695, D570, D792, D635. Se determinó una temperatura de 170 °C y un tiempo de 150 min permiten obtener ladrillos compactos, sin quema del plástico o emisión de gases. Así mismo, se concluyó que los ladrillos de plástico reciclado presentan una resistencia a la compresión mayor que los ladrillos convencionales, pero menor absorción de agua y densidad, especialmente en el caso de los ladrillos de polietileno. [ABSTRACT FROM AUTHOR]

Copyright of Superficies y Vacío is the property of Sociedad Mexicana de Ciencia y Tecnologia de Superficies y Materiales and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A great amount of gaseous pollutants are discharged directly into the atmosphere including VOCs due to industrial activity. Gaseous phase of photooxidation consisting of continuous irradiation of a catalyst based on TiO2, shows potential uses in removing VOCs in airstreams; in this sense and with regard to technology, the main challenge is the design and optimization of the reactor to get both high residence times and high degradation levels. That is why the basic aspects of heterogeneous photocatalysis in the gaseous phase, the concept of photoreactors and their developing, both in their beginnigs and in their evolution in the search for better removal efficiency and optimization of irradiation sources are presented here. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the sliding wear behavior of γ-irradiated linear polyethylene. The polymers used were two linear polyethylenes that were irradiated by γ rays at room temperature. Equal total doses of 2, 5, 10 and 20 Mrad were applied. Tribological tests were performed in a Pin On Disc tribometer with normal loads between 2, 5 and 15 N. The results show that the wear rate increases with the applied load in the case of the samples irradiated with the lowest doses, while the wear rate displays a maximum with the applied load in the samples irradiated with the highest dose. [ABSTRACT FROM AUTHOR]

Composites made of recycled low density polyethylene and wood or bark flour of Pinus radiata D. Don were tested, the effect of the flour content and density of the composites on physical and mechanical properties were determinated. These both types of composites were prepared by injection moulding and without chemical additives at 20/80, 40/60 and 60/40 of flour/polyethylene (w/w). Several physical and mechanical properties were measured. The results were tested for comparison of means and Multiple Linear Regression Analysis (ARLM), followed by the method stepwise (SWM). The results indicate that the physical properties and the E increased with increasing flour content, while the tensile strength and the hardness tended to decline. The composites made with bark flour had higher stiffness, absorbed less water and swelled less, and show similar hardness than the composite made with wood flour, but only the composite with 20% (w/w) of bark flour showed greater tensile strength than the others composites. The content of flour was the variable that most affects the properties evaluated, except to the E and the hardness of the wood flour composites, they were most affected by their density. [ABSTRACT FROM AUTHOR]

The case of a male 76 year-old patient with a history of total hip replacement surgery is presented herein. The patient had tumors in the iliac fossa with swelling of the thigh and pain upon hip flexion and extension. The complementary ultrasound and computed tomography show a large lobed cystic tumor in the left iliac fossa, 7 cm in diameter, close to the prosthesis. The diagnosis was psoas bursitis secondary to the release of polyethylene particles that caused compression and thrombosis of the superficial femoral vein. Cyst formation caused by polyethylene disease after total hip arthroplasty is infrequent. [ABSTRACT FROM AUTHOR]

The subject of this work was to define the shelf life, at room temperature, of soft crust bread with 11 % (flour weight) soy fiber. Four different variants were studied: not packed and packed without addition of calcium propionate, and packed and not packed with addition of 0,3 % of calcium propionate. The sensorial microbiological characteristics and were determined during the storage. To know the durability the results were processed statistically as incomplete failure data using the statistical method "plot risk". The shelf life at room temperature of the breads with soy fiber was 2 days without packing and 4 days with packed. The refusal took place due to deterioration of the freshness, flavor and also firmness for those not packed, the stability. The incorporation of calcium propionate at 0,3 % had any increase in the shelf life of the bread, but it allowsed that the packed breads maintain a better microbiological quality during its useful life. [ABSTRACT FROM AUTHOR]

In the present work is carried out a study of the demand of High Density Polyethylene at national scale, and in a particular way in the provinces of Ciego de Ávila and Camagüey aimed at predicting the capacity of a plant for the production of polyethylene of high density from ethylene obtained by means of the alcho-chemical Route. For it, it was applied the Method of the Initial no-Null Demand, proposed by Rudd and Watson, starting from the polyethylene consumption in the main industries. To minimize the financial uncertainty it was carried out the analysis parting from an interest rate of 0.15, with values above and below this (0.12 and 0.18). It was used, also 20 % -over designs value , recommended by Rudd and Watson for the Classic Design. [ABSTRACT FROM AUTHOR]

The objective of this work was to evaluate different flexible materials and its close. It didn't meet significant difference as for the vapour water permeability of the folding box of 2 kg of cookies with interior polypropylene's bag closed with loop and the variant with interior polypropylene's bag, tied with cotton thread. The variant of folding box with interior highdensity polyethylene's bag closed white plastic seal and external cover of polyvinyl chloride retractile film presented a water vapour permeability 2, 85 times major that the other ones. The cookie packed in box of folding cardboard with interior bag of polypropylene, closed in its superior part by means of loop presented a bigger conservation of its quality and sensorial preference for the appraisers. [ABSTRACT FROM AUTHOR]

In this work, polyethylenes modified with acrylamide (AAm) and dyethylmaleate (DEM) to improve their apolar character in materials with potential applications for orthopedic surgery were evaluated by the thermal fractionation technique known as Successive Self-nucleation and Annealing (SSA). Similarly PE belonging to parts for orthopedic joint implants, that were prosthetic components formed by metal-polyethylene pairs, were evaluated. With the aid of SSA, the approximate amount of crosslinks in the material was estimated. These results demonstrate that the SSA technique is a powerful tool for characterizing PE parts for biomedical use. [ABSTRACT FROM AUTHOR]

The performance of Ziegler-Natta catalyst in polymerization reaction is affected by the presence of active impurities and the productivity of these system decreases accordingly. the effect of three different species (namely methyl ketone, ethanol or water) on the performance of TiCl4/MgCl2/Al(CH2CH3)3 catalytic system used in the ethylene polymerization, was studied. It was found that the higher the concentration of impurities causes lower the productivity. When methyl ketone was used as a contaminant, the productivity decreased sharply. [ABSTRACT FROM AUTHOR]