Strategies to improve the mechanical properties of starch-based materials: plasticization and natural fibers reinforcement

Biodegradable polymers are starting to be introduced as raw materials in the food-packaging market. Nevertheless, their price is very high. Starch, a fully biodegradable and bioderived polymer is a very interesting alternative due to its very low price. However, the use of starch as the polymer matrix for the production of rigid food packaging, such as trays, is limited due to its poor mechanical properties, high hidrophilicity and high density. This work presents two strategies to overcome the poor mechanical properties of starch. First, the plasticization of starch with several amounts of glycerol to produce thermoplastic starch (TPS) and second, the production of biocomposites by reinforcing TPS with promising fibers, such as barley straw and grape waste. The mechanical properties obtained are compared with the values predicted by models used in the field of composites; law of mixtures, Kerner-Nielsen and Halpin-Tsai. To evaluate if the materials developed are suitable for the production of food-packaging trays, the TPS-based materials with better mechanical properties were compared with commercial grades of oil-based polymers, polypropylene (PP) and polyethylene-terphthalate (PET), and a biodegradable polymer, polylactic acid (PLA).

Skeletal muscle degeneration and regeneration after injection of bothropstoxin-II, a phospholipase A2 isolated from the venom of the snake Bothrops jararacussu

A myotoxic phospholipase A2, named bothropstoxin II (BthTX-II), was isolated from the venom of the South American snake Bothrops jararacussu and the pathogenesis of myonecrosis induced by this toxin was studied in mice. BthTX-II induced a rapid increase in plasma creatine kinase levels. Histological and ultrastructural observations demonstrate that this toxin affects muscle fibers by first disrupting the integrity of plasma membrane, as delta lesions were the earliest morphological alteration and since the plasma membrane was interrupted or absent in many portions. In agreement with this hypothesis, BthTX-II released peroxidase entrapped in negatively charged multilamellar liposomes and behaved as an amphiphilic protein in charge shift electrophoresis, an indication that its mechanism of action might be based on the interaction and disorganization of plasma membrane phospholipids. Membrane damage was followed by a complex series of morphological alterations in intracellular structures, most of which are probably related to an increase in cytosolic calcium levels. Myofilaments became hypercontracted into dense clumps which alternated with cellular spaces devoid of myofibrillar material. Later on, myofilaments changed to a hyaline appearance with a more uniform distribution. Mitochondria were drastically affected, showing high amplitude swelling, vesiculation of cristae, formation of flocculent densities, and membrane disruption. By 24 hr, abundant polymorphonuclear leucocytes and macrophages were observed in the interstitial space as well as inside necrotic fibers. Muscle regeneration proceeded normally, as abundant myotubes and regenerating myofibers were observed 7 days after BthTX-II injection. By 28 days regenerating fibers had a diameter similar to that of adult muscle fibers, although they presented two distinctive features: central location of nuclei and some fiber splitting. This good regenerative response may be explained by the observation that BthTX-II does not affect blood vessels, nerves, or basal laminae. © 1991.

Evaluation of hollow fiberoptic tips for the conduction of Er : YAG laser

Objective: The use of Er:YAG laser operating in the 3 μm range with adjustable power and pulses has become popular for dental and medical practice due to its high photoablative capacity, surgical precision and antimicrobial action. Background data: The existing fiberoptic tips irradiate lasers parallel to the long axes of the tooth limiting its efficiency in the root canal. Methods: We evaluated hollow fiberoptic tips obtained from silicate glass as a means of Er:YAG laser conduction in dental procedures. The fiber tips were molded from capillary tubes with different profiles so that their ends would have cylindric, conical or spherical shapes. The performance of the three fibers as a means of propagation of Er:YAG (λ = 2.94 μm) laser radiation was compared to that of a solid sapphire fiber at 10 Hz and 200 mJ and of 20 Hz and 500 mJ. The profiles of frontal and lateral burning were visualized on thermal paper. Results: Analysis of these profiles demonstrated that the sapphire tip and the hollow fiber of cylindric section did not differ significantly in the profiles of frontal burning, and no lateral burning was detected. The fibers of the conical and spherical sections, although presenting attenuation in the frontal output power, showed a larger burning area in the frontal profile, in addition to producing lateral burning. Conclusions: The results indicate that commercial hollow fiberoptics have advantages such as easy manufacture of the different tip shapes, great adaptability, low cost, and a low loss of transmission. © Mary Ann Liebert, Inc.

Influence of time evolution in the modulus of elasticity of concrete reinforced by carbon fibers

The modulus of elasticity is an important property for the behavior analysis of concrete structures. This research evaluated the strain difference between concrete specimens with and without the application of laminate carbon fiber composites as well as the variation time, in months, of the axial strength compression and modulus of elasticity. Through the experimental results, it is concluded that increases in compressive strength and modulus of elasticity are more significant in the specimens without reinforcement.

Orcs Inc. - jogo de tabuleiro empresarial: capacitação profissional através do lúdico

A proposta deste trabalho é criar um Jogo de Tabuleiro Empresarial voltado para a capacitação de profissionais de micro e pequenas empresas em comunicação, juntamente com a aluna de Design da Unesp - Bauru, Tatiana Kurokawa Hasimoto. Observando o poder dessa ferramenta em outras áreas do conhecimento (como administração e empreendedorismo) exploramos o potencial da área de comunicação para a criação de um Jogo de Tabuleiro Empresarial, voltado para a capacitação e seleção. O trabalho tem como base um mapeamento de microempresas da cidade de Bauru, realizado pelo Núcleo de Opinião da UNESP, coordenado pela Profª Drª Célia Maria Retz Godoy dos Santos, onde foi possível perceber a falta de conhecimento sobre a área de comunicação por essas empresas. O objetivo é mostrar a importância da comunicação e principalmente como o profissional de Relações Públicas pode atuar nessas empresas

Honors, Inc.

Academics across the country are having an allergic reaction to the corporate model of operation being adopted by many universities. Terms like branding, collateral materials, budget controls, marketing strategies, and outcomes are causing a panic among faculty who believe that a customer satisfaction approach to higher education is anti-intellectual and that it leads to grade inflation, teaching toward evaluations, and learning as product, not process. Honors programs in particular, often the standard bearers of undergraduate academic standards, are being asked to market themselves not only to the top prospective students, but also to the university administration at large. Honors is frequently the default focus group expected to show the rest of the university programs and departments ‘How it is done,’ or rather, ‘How it is done according to standard.’ By ‘it,’ of course, I mean marketing our curriculum, selling our program, and branding our product.

Agriculture Builders of Nebraska Inc.

It’s a pleasure to be able to speak with you today. I want you to know that Virginia and I are delighted to be in Nebraska. And I’m especially happy to have arrived in the state at a time where I can, on my 7th day on the job, learn so much about UNL just by reading the state’s largest newspaper.

Agriculture Builders of Nebraska, Inc. Morning Session

Good morning! On behalf of the Institute of Agriculture and Natural Resources representatives here this morning, I want to express our very real pleasure in being with you, and our very great appreciation of all that you do. We in the Institute value the Agriculture Builders of Nebraska highly. Your support for our work and the wise counsel of ABN members has been invaluable to me personally since my arrival in Nebraska, and I know that is true of the entire Institute, as well. In fact, the thoughtful perspective and the confidential advice of the ABN Executive Committee in the recent third-round of budget cutting decisions we faced in the Institute helped me work through what we had to do in that very, very difficult round of cuts.

Agriculture Builders of Nebraska, Inc.

There’s a story that a construction foreman one day noticed one of his workers pushing his wheelbarrow upside down around the work site. “Hey,” the foreman shouted, “turn that thing right side up!” The man with the wheelbarrow looked at him in surprise. “Don’t be silly,” he said. “Every time I do that, they put bricks in it!” I think of that story sometimes, in the midst of these difficult economic times, as our states, its people, and its university, in turn, wrestle with budge cuts. Wouldn’t it be great if we all could just turn our wheelbarrows over and say, “No thanks, no more brick! No more heavy loads to haul!”

Agriculture Builders of Nebraska, Inc.

What a pleasure it is to be with you here this morning! And How startling it is to realize a whole year has passed since we last gathered at this meeting. So much has occurred in that year.

Agriculture Builders of Nebraska, Inc. Annual Meeting

Those of us in the Institute of Agriculture and Natural Resources at your land-grant university view ourselves as partners with Nebraska. Taking the resources of this great university to the citizens of our state is a mission we take very, very seriously. We work hard to apply the university's resources in a diverse number of ways to benefit Nebraska. Today it is my very great pleasure to have this opportunity to provide a brief report to you, our partners, on some of the ways we are returning your investment in us to benefit our state.

Agriculture Builders of Nebraska, Inc. Annual Meeting

It's such a pleasure to be here with you this morning. Each year I look forward to this opportunity to visit with you, to hear your thoughts, to thank you for all you do for the Institute of Agriculture and Natural Resources, and for the University of Nebraska. We truly appreciate your support and your hard work on our behalf. I think Nebraska is extremely fortunate to have ABN at work in our state.

Agriculture Builders of Nebraska, Inc. Annual Meeting

Let me start today by saying thank you. Thank you, each of you, for your strong support of the Institute of Agriculture and Natural Resources and the University of Nebraska.

Agriculture Builders of Nebraska, Inc.

Good morning! There's a lot of information I want to share with you in a short amount of time, so I'm going to get right to it.

Preparation and evaluation of the electrospun chitosan/PEO fibers for potential applications in cartilage tissue engineering

Fibrous materials have morphological similarities to natural cartilage extracellular matrix and have been considered as candidate for bone tissue engineering scaffolds. In this study, we have evaluated a novel electrospun chitosan mat composed of oriented sub-micron fibers for its tensile property and biocompatibility with chondrocytes (cell attachment, proliferation and viability). Scanning electronic microscope images showed the fibers in the electrospun chitosan mats were indeed aligned and there was a slight cross-linking between the parent fibers. The electrospun mats have significantly higher elastic modulus (2.25 MPa) than the cast films (1.19 MPa). Viability of cells on the electrospun mat was 69% of the cells on tissue-culture polystyrene (TCP control) after three days in culture, which was slightly higher than that on the cast films (63% of the TCP control). Cells on the electrospun mat grew slowly the first week but the growth rate increased after that. By day 10, cell number on the electrospun mat was almost 82% that of TCP control, which was higher than that of cast films (56% of TCP). The electrospun chitosan mats have a higher Young’s modulus (P <0.01) than cast films and provide good chondrocyte biocompatibility. The electrospun chitosan mats, thus, have the potential to be further processed into three-dimensional scaffolds for cartilage tissue repair.