Activated lignin‒chitosan extruded blends for efficient adsorption of methylene blue

This work investigates the production of activated lignin-chitosan extruded (ALiCE) pellets with controlled particle size distribution (almost spherical: dp ~500‒1000µm) for efficient methylene blue adsorption. The novel preparation method employed in this study successfully produced activated lignin-chitosan pellets. Structural and morphological characterizations were performed using BET, FTIR and SEM-EDX analyses. The influence of contact time, solution pH, ionic strength, initial adsorbate concentration and desorption studies was investigated. The experimental data fitted well with the Langmuir isotherm (R2 = 0.997), yielding a maximum adsorption capacity of 36.25mg/g. The kinetic data indicated that methylene blue (MB) adsorption onto ALiCE can be represented by the pseudo second-order-model with intraparticle processes initially controlling the process of MB adsorption. Overall, these results indicate that the novel ALiCE offers great potential for removing cationic organic pollutants from rivers and streams.

Banana and abaca fiber-reinforced plastic composites obtained by rotational molding process

Natural fibers can be used in rotational molding process to obtain parts with improved mechanical properties. Different approaches have been followed in order to produce formulations containing banana or abaca fiber at 5% weight, in two- and three-layer constructions. Chemically treated abaca fiber has also been studied, causing some problems in processability. Fibers used have been characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), optical microscopy, and single-fiber mechanical tests. Rotomolded parts have been tested for tensile, flexural, and impact properties, demonstrating that important increases in elastic modulus are achieved with these fibers, although impact properties are reduced. © 2013 Copyright Taylor and Francis Group, LLC.

The Plastic Coupled Map Lattice: a Novel Image‐processing Paradigm

Coupled map lattices (CML) can describe many relaxation and optimization algorithms currently used in image processing. We recently introduced the ‘‘plastic‐CML’’ as a paradigm to extract (segment) objects in an image. Here, the image is applied by a set of forces to a metal sheet which is allowed to undergo plastic deformation parallel to the applied forces. In this paper we present an analysis of our ‘‘plastic‐CML’’ in one and two dimensions, deriving the nature and stability of its stationary solutions. We also detail how to use the CML in image processing, how to set the system parameters and present examples of it at work. We conclude that the plastic‐CML is able to segment images with large amounts of noise and large dynamic range of pixel values, and is suitable for a very large scale integration(VLSI) implementation.

Moisture Desorption Studies on Polymer Hydrated and Vacuum Extruded Bentonite Clay Mat

Moisture desorption observations from two bentonite clay mats subjected to ten environmental zones with individually different combinations of laboratory-controlled constant temperatures (between 20 °C and 40 °C) and relative humidity (between 15% and 70%) are presented. These laboratory observations are compared with predictions from mathematical models, such as thin-layer drying equations and kinetic drying models proposed by Page, Wang and Singh, and Henderson and Pabis. The quality of fit of these models is assessed using standard error (SE) of estimate, relative percent of error, and coefficient of correlation. The Page model was found to better predict the drying kinetics of the bentonite clay mats for the simulated tropical climates. Critical study on the drying constant and moisture diffusion coefficient helps to assess the efficacy of a polymer to retain moisture and control desorption through water molecule bonding. This is further substantiated with the Guggenheim–Anderson–De Boer (GAB) desorption isotherm model which is presented.

Small bowel occlusion due to giant perineal hernia: abdominal approach with plastic perineal reconstruction

A perineal hernia is defined as a protrusion of peritoneal or extraperitoneal content through a pelvic floor defect. A 64-year-old woman with a bowel occlusions due to a giant postoperative perineal hernia was admitted to our hospital. We describe abdominal approach with plastic perineal reconstruction.

Electrolytic cells for plastic waste recycling

The current project assesses potential molten alloy anodes for Solid Oxide Fuel Cells (SOFC) running on solid waste. A detailed phase diagram study was performed to locate probable anode systems. The molten metal oxide system PbO-Sb2O3 was selected as a possible molten alloy anode for this application. A detailed vapour pressure study of this system was performed. Several cells were fabricated to experimentally assess the electrochemical properties of this system. The work reveals several unexpected limiting features such as the incompatibility between the platinum and the chosen alloy. A second cell was built, this time using rhenium wires instead, preventing such reaction. However, the rhenium wire sublimes under oxidizing conditions (air) and the sealing glass and the chosen alloy system react with each other under long term use. Considering all these issues, a third cell design was conceived, surpassing some obstacles and providing some initial information regarding the electrochemical behaviour. The current project shows that many parameters need to be taken into account to ensure materials compatibility. For the PbOSb2O3 system, the high volatility of Sb2O3 was a serious limitation that can only be addressed through the application of new contact wires or sealing materials and conditions. Nonetheless, the project highlights several other potential systems that can be considered, such as Pb11Ge3O17, Pb3GeO5, Pb5Ge3O11, Bi2CuO4, Bi2PdO4, Bi12GeO20.

Experimental Modeling of Twin-Screw Extrusion Processes to Predict Properties of Extruded Composites

Twin-screw extrusion is used to compound fillers into a polymer matrix in order to improve the properties of the final product. The resultant properties of the composite are determined by the operating conditions used during extrusion processing. Changes in the operating conditions affect the physics of the melt flow, inducing unique composite properties. In the following work, the Residence Stress Distribution methodology has been applied to model both the stress behavior and the property response of a twin-screw compounding process as a function of the operating conditions. The compounding of a pigment into a polymer melt has been investigated to determine the effect of stress on the degree of mixing, which will affect the properties of the composite. In addition, the pharmaceutical properties resulting from the compounding of an active pharmaceutical ingredient are modeled as a function of the operating conditions, indicating the physical behavior inducing the property responses.

Performance and ruminal morphologic characteristics of Saanen kids fed ground, pelleted or extruded total ration

The aim of the present study was to determine feed intake and average weight gain and to evaluate the ruminal morphologic characteristics of Saanen kids slaughtered at 30, 45 and 60 days of age, according to a completely randomized design. Thirty-six non-castrated male Saanen kids were fed ground total ration, pelleted total ration, or extruded total ration. Feed intake and refusals were controlled daily and the animals were weighed at birth and then once a week. Newborn kids received a milk replacer and were weaned at 45 days. Immediately after slaughter, the animals were eviscerated, the entire digestive apparatus was removed from the carcass. The reticulo-rumen was separated, emptied, washed and weighed. Samples were collected from the dorsal sac, pillar area and ventral sac of the rumen, fixed for about 24h in Bouin's solution, dehydrated, embedded in Histosec and cut into 5 mu m sections. Results showed that dry matter intake (DMI) at weaning and post-weaning and weight gain were higher (P < 0.05) in animals that received the pelleted total ration. The weight of the reticulo-rumen accompanied body development and was heavier in these animals. Histologically, after weaning ruminal papillae were more developed in animals that received pelleted total ration. Length of papillae increased with increase of age. The ratio of papillary height to papillary width increased with age in the ventral sac and until weaning (P > 0.05). We conclude that the pelleting process of the total ration favored increased intake, with a 46.7% increase in weight gain and increase in rumen weight and papillae length, suggesting that best results are obtained with this processing. In general, no difference was observed between the results obtained with extruded and ground total ration, although animals fed extruded total ration showed an increase in rumen weight and papillae width. (c) 2004 Elsevier B.V All rights reserved.

Dynamics of Granular Crystals with Elastic-Plastic Contacts

We study the behavior of granular crystals subjected to impact loading that creates plastic deformation at the contacts between constituent particles. Granular crystals are highly periodic arrangements of spherical particles, arranged into densely packed structures resembling crystals. This special class of granular materials has been shown to have unique dynamics with suggested applications in impact protection. However, previous work has focused on very low amplitude impacts where every contact point can be described using the Hertzian contact law, valid only for purely elastic deformation. In this thesis, we extend previous investigation of the dynamics of granular crystals to significantly higher impact energies more suitable for the majority of applications. Additionally, we demonstrate new properties specific to elastic-plastic granular crystals and discuss their potential applications as well. We first develop a new contact law to describe the interaction between particles for large amplitude compression of elastic-plastic spherical particles including a formulation for strain-rate dependent plasticity. We numerically and experimentally demonstrate the applicability of this contact law to a variety of materials typically used in granular crystals. We then extend our investigation to one-dimensional chains of elastic-plastic particles, including chains of alternating dissimilar materials. We show that, using the new elastic-plastic contact law, we can predict the speed at which impact waves with plastic dissipation propagate based on the material properties of the constituent particles. Finally, we experimentally and numerically investigate the dynamics of two-dimensional and three-dimensional granular crystals with elastic-plastic contacts. We first show that the predicted wave speeds for 1D granular crystals can be extended to 2D and 3D materials. We then investigate the behavior of waves propagating across oblique interfaces of dissimilar particles. We show that the character of the refracted wave can be predicted using an analog to Snell's law for elastic-plastic granular crystals and ultimately show how it can be used to design impact guiding "lenses" for mitigation applications.

Transport of Pirarucu Arapaima gigas juveniles in plastic bag

Este estudo examinou as respostas de estresse de juvenis de pirarucu transportados em sistema fechado. Pirarucu (Arapaima gigas) é um peixe nativo da bacia Amazônica, da família Osteoglossidae que possui respiração aérea obrigatória. Foi realizado um transporte de curta duração (6 h) em sacos de polietileno inflados com ar atmosférico (grupo ar) ou com oxigênio puro (grupo oxi). O oxigênio dissolvido foi o único parâmetro de qualidade da água que apresentou diferença estatística entre os grupos, e como esperado, o oxigênio estava supersaturado para o grupo oxi. Não houve mortalidade após o transporte em ambos os grupos. Os peixes se alimentaram 36 h após o transporte e apresentaram um consumo de ração habitual após 72 h. As respostas fisiológicas foram semelhantes nos dois grupos. O cortisol não apresentou mudança significativa durante o período de amostragem. Ao contrário da maioria das espécies, os valores de cortisol se apresentaram inalterados nos dois grupos durante a amostragem, enquanto a glicose teve um aumento significativo até 12 h após o transporte. Os resultados mostram que o transporte de pirarucu em sacos de polietileno pode ser realizado com ar atmosférico ou oxigênio puro, uma vez que as respostas de estresse, a qualidade da água e o comportamento alimentar após 36 h foram similar entre os grupos.

TEST-ANALYSIS MODEL CORRELATION AND CALIBRATION OF A MULTI-COMPONENT PLASTIC PART

The goal of this project is to learn the necessary steps to create a finite element model, which can accurately predict the dynamic response of a Kohler Engines Heavy Duty Air Cleaner (HDAC). This air cleaner is composed of three glass reinforced plastic components and two air filters. Several uncertainties arose in the finite element (FE) model due to the HDAC’s component material properties and assembly conditions. To help understand and mitigate these uncertainties, analytical and experimental modal models were created concurrently to perform a model correlation and calibration. Over the course of the project simple and practical methods were found for future FE model creation. Similarly, an experimental method for the optimal acquisition of experimental modal data was arrived upon. After the model correlation and calibration was performed a validation experiment was used to confirm the FE models predictive capabilities.

Intergranular Corrosion and Stress Corrosion Cracking of Extruded AA6005A

A research program focused on understanding the intergranular corrosion (IGC) and stress corrosion cracking (SCC) behavior of AA6005A aluminum extrusions is presented in this dissertation. The relationship between IGC and SCC susceptibility and the mechanisms of SCC in AA6005A extrusions were studied by examining two primary hypotheses. IGC susceptibility of the elongated grain structure in AA6005A exposed to low pH saltwater was found to depend primarily on the morphology of Cu-containing precipitates adjacent to the grain boundaries in the elongated grain structure. IGC susceptibility was observed when a continuous (or semi-continuous) film of Cu-containing phase was present along the grain boundaries. When this film coarsened to form discrete Cu-rich precipitates, no IGC was observed. The morphology of the Cu-rich phase depended on post-extrusion heat treatment. The rate of IGC penetration in the elongated grain structure of AA6005A-T4 and AA6005A-T6 extrusions was found to be anisotropic with IGC propagating most rapidly along the extrusion direction, and least rapidly along the through thickness direction. A simple 3-dimensional geometric model of the elongated grain structure was accurately described the observed IGC anisotropy, therefore it was concluded that the anisotropic IGC susceptibility in the elongated grain structure was primarily due to geometric elongation of the grains. The velocity of IGC penetration along all directions in AA6005A-T6 decreased with exposure time. Characterization of the local environment within simulated corrosion paths revealed that a pH gradient existed between the tip of the IGC path and the external environment. Knowledge of the local environment within an IGC path allowed development of a simple model based on Fick's first law that considered diffusion of Al3+ away from the tip of the IGC path. The predicted IGC velocity agreed well with the observed IGC velocity, therefore it was determined that diffusion of Al3+ was the primary factor in determining the velocity of IGC penetration. The velocity of crack growth in compact tensile (CT) specimens of AA6005A-T6 extrusion exposed to 3.5% NaCl at pH = 1.5 was nearly constant over a range of applied stress intensities, exposure times, and crack lengths. The crack growth behavior of CT specimens of AA6005A-T6 extrusion exposed to a solution of 3.5% NaCl at pH = 2.0 exhibited similar behavior, but the crack velocity was ~10.5X smaller than that those exposed to a solution at pH =1.5. Analysis of the local stress state and polarization behavior at the crack tip predicted that increasing the pH of the bulk solution from 1.5 to 2.0 would decrease the corrosion current density at the crack tip by approximately 11.8X. This predicted decrease in corrosion current density was in reasonable agreement with the observed decrease in SCC velocity associated with increasing the solution pH from 1.5 to 2.0. The agreement between the predicted and observed SCC velocities suggested that the electrochemical reactions controlling SCC in AA6005A-T6 extrusions are ultimately controlled by the pH gradient that exists between the crack tip and external environment.