Preparation and characterisation of biodegradable starch-based nanocomposite materials

Different formulations of biodegradable starch-polyester blend nanocomposite materials have been film blown on a pilot scale film blowing tower. The physical properties of different films have been examined by thermal and mechanical analysis and X-ray diffraction. The results show that the addition of an organoclay (from 0 to 5 wt%) significantly improves both the processing and tensile properties over the original starch blends. Wide angle X-ray diffraction (WAXD) results indicate that the best results were obtained for 30wt% starch blends, and the level of delamination depends on the ratio of starch to polyester and amount of organoclay added. The crystallisation temperature of the nanocomposite blends is significantly lower than the base blend. This is probably due to the platelets inhibiting order, and hence crystallisation, of the starch and polyester. The mechanical and thermal properties of the blends are also sensitive to the way the clay particles are dispersed. (C) 2003 Society of Chemical Industry.

Pyrazole or tris(pyrazolyl)ethanol oxo-vanadium(IV) complexes as homogeneous or supported catalysts for oxidation of cyclohexane under mild conditions

The oxovanadium(IV) complexes [VO(acac)(2)(Hpz)].HC(pz)(3) 1.HC(pz)(3) (acac= acetylacetonate, Hpz = pyrazole, pz = pyrazoly1) and [VOCl2{HOCH2C(pz)(3)}] 2 were obtained from reaction of [VO(acac)(2)] with hydrotris(1-pyrazolyl)methane or of VCl(3)with 2,2,2-tris(1-pyrazolyl)ethanol. The compounds were characterized by elemental analysis, IR, Far-IR and EPR spectroscopies, FAB or ESI mass-spectrometry and, for 1, by single crystal X-ray diffraction analysis. 1 and 2 exhibit catalytic activity for the oxidation of cyclohexane to the cyclohexanol and cyclohexanone mixture in homogeneous system (TONS up to 1100) under mild conditions (NCMe, 24h, room temperature) using benzoyl peroxide (BPO), tert-butyl hydroperoxide (TBHP), m-chloroperoxybenzoic acid (mCPBA), hydrogen peroxide or the urea-hydrogen peroxide adduct (UHP) as oxidants. 1 and 2 were also immobilized on a polydimethylsiloxane membrane (1-PDMS or 2-PDMS) and the systems acted as supported catalysts for the cyclohexane oxidation using the above oxidants (TONs up to 620). The best results were obtained with mCPBA or BP0 as oxidant. The effects of various parameters, such as the amount of catalyst, nitric acid, reaction time, type of oxidant and oxidant-to-catalyst molar ratio, were investigated, for both homogeneous and supported systems. (C) 2012 Elsevier B.V. All rights reserved.

Influence of the pre-treatments on the properties of biodegradable films from bovine hair

The replacement of conventional synthetic films and coatings by biodegradable alternatives reduces the use of non-renewable resources and waste disposal problems. Considering that Portugal is a major producer of leather, and consequently a large producer of related wastes, in this research, bovine hair was tested for the production of biodegradable films directly by thermo-compression, allowing waste valorisation and reduction of environmental pollution. The aim of this study was to determine the influence of the different pre-treatments performed by two processes (removal by mechanical action and removal by chemical process), applied to bovine hair, in order to obtain a biodegradable film with appropriate properties. Mechanical properties for these films were evaluated, namely strain at break, stress at break and Young modulus. Additionally colour, solubility and swelling in water were also studied. The mechanical removal hair only produced films with Na2S treatment. Chemical removed hair (immunization) depends of the pre-treatment and the degreasing with petroleum ether or sodium sulphide pre-treatment leads better mechanical properties. The results obtained indicated that the pre-treatments have an important role in the final properties of biodegradable films.

Friction and wear in thrust ball bearings lubricated with biodegradable greases

Thrust ball bearings lubricated with several different types of grease, including three biodegradable low-toxicity greases, were tested in a modified four-ball machine in order to evaluate the bearing friction torque. At the end of each test, grease samples were obtained and analysed through ferrography, allowing the quantification and evaluation of the bearing wear. In order to compare the grease performance in terms of friction and wear, a correlation between the grease characteristics (base oil, bleed oil, thickener structure, and rheological parameters) and the experimental results was established.

Baeyer-Villiger oxidation of Keotones catalysed by rhenium complexes bearing N- Or Oxo-Ligands

Rhenium (I, III-V or VII) complexes bearing N-donor or oxo-ligands catalyse the Baeyer-Villiger oxidation of cyclic and linear ketones (e.g. 2-methylcyclohexanone, 2-methylcyclopentanone, cyclohexanone, cyclopentanone, cyclobutanone and 3,3-dimethyl-2-butanone) into the corresponding lactones or esters, in the presence of aqueous H2O2 (30%). The effects of various reaction parameters are studied allowing to achieve yields up to 54%.

Oxo-molybdenum(VI) complexes containing chiral ligands: catalytic applications in selective epoxidations

Dissertation presented to obtain the Ph.D. degree in Chemistry

Brazilian fruit pulps as functional foods and additives: Evaluation of bioactive compounds

Eight tropical fruit pulps from Brazil were simultaneously characterised in terms of their antioxidant and antimicrobial properties. Antioxidant activity was screened by DPPH radical scavenging activity (126–3987 mg TE/100 g DW) and ferric reduction activity power (368–20819 mg AAE/100 g DW), and complemented with total phenolic content (329–12466 mg GAE/100 g DW) and total flavonoid content measurements (46–672 mg EE /100 g DW), whereas antimicrobial activity was tested against the most frequently found food pathogens. Acerola and açaí presented the highest values for the antioxidant-related measurements. Direct correlations between these measurements could be observed for some of the fruits. Tamarind exhibited the broadest antimicrobial potential, having revealed growth inhibition of Pseudomonas aeruginosa. Escherichia coli, Listeria monocytogenes, Salmonella sp. and Staphylococcus aureus. Açaí and tamarind extracts presented an inverse relationship between antibacterial and antioxidant activities, and therefore, the antibacterial activity cannot be attributed (only) to phenolic compounds.

Validation of alternative additives for paste production

Dissertation presented to confer Master Degree in Chemical and Biochemical Engineering

The influence of use additives on nitrous oxide emission during swine slurry composting.

use of additives (Mg/P and nitrification inhibitor dicyandiamide - DCD), on nitrous oxide emission during swine slurry composting. The experiment was run in duplicate; the gas was monitored for 30 days in different treatments (control, DCD, Mg/P and DCD + Mg/P). Nitrous oxide emissions rate (mg of N2O-N.day-1) and the accumulated emissions were calculated to compare the treatments. Results has shown that emissions of N-N2O were reduced by approximately 70, 46 and 96% through the additions of DCD, MgCl2.6H2O + H3PO4 and both additives, respectively, compared to the control. Keywords Composting; swine slurry; additives; nitrous

Poly lactic acid based biodegradable stents and functionalization techniques: brief review

Commercial stents, especially metallic ones, present several disadvantages, and this gives rise to the necessity of producing or coating stents with different materials, like natural polymers, in order to improve their biocompatibility and minimize the disadvantages of metallic ones. This review paper discusses some applications of natural-based polymers in stents, namely polylactic acid (PLA) for stent development and chitosan for biocompatible coatings of stents . Furthermore, some effective stent functionalization techniques will be discussed, namely Layer by Layer (LBL) technique.

Highly functional and biodegradable nanofibrous scaffolds combined with stem cells for bone and cartilage tissue engineering

Among the various possible embodiements of Advanced Therapies and in particular of Tissue Engineering the use of temporary scaffolds to regenerate tissue defects is one of the key issues. The scaffolds should be specifically designed to create environments that promote tissue development and not merely to support the maintenance of communities of cells. To achieve that goal, highly functional scaffolds may combine specific morphologies and surface chemistry with the local release of bioactive agents. Many biomaterials have been proposed to produce scaffolds aiming the regeneration of a wealth of human tissues. We have a particular interest in developing systems based in nanofibrous biodegradable polymers1,2. Those demanding applications require a combination of mechanical properties, processability, cell-friendly surfaces and tunable biodegradability that need to be tailored for the specific application envisioned. Those biomaterials are usually processed by different routes into devices with wide range of morphologies such as biodegradable fibers and meshes, films or particles and adaptable to different biomedical applications. In our approach, we combine the temporary scaffolds populated with therapeutically relevant communities of cells to generate a hybrid implant. For that we have explored different sources of adult and also embryonic stem cells. We are exploring the use of adult MSCs3, namely obtained from the bone marrow for the development autologous-based therapies. We also develop strategies based in extra-embryonic tissues, such as amniotic fluid (AF) and the perivascular region of the umbilical cord4 (Whartonâ s Jelly, WJ). Those tissues offer many advantages over both embryonic and other adult stem cell sourcess. These tissues are frequently discarded at parturition and its extracorporeal nature facilitates tissue donation by the patients. The comparatively large volume of tissue and ease of physical manipulation facilitates the isolation of larger numbers of stem cells. The fetal stem cells appear to have more pronounced immunomodulatory properties than adult MSCs. This allogeneic escape mechanism may be of therapeutic value, because the transplantation of readily available allogeneic human MSCs would be preferable as opposed to the required expansion stage (involving both time and logistic effort) of autologous cells. Topics to be covered: This talk will review our latest developments of nanostructured-based biomaterials and scaffolds in combination with stem cells for bone and cartilage tissue engineering.

Biodegradable drug-eluting stents: Targeting urothelial tumors of upper urinary tract

INTRODUCTION & OBJECTIVES: Urothelial tumors of upper urinary tract are ranked among the most common types of cancers worldwide. The current standard therapy to prevent recurrence is intravesical Bacillus Calmetteâ Guerin (BCG) immunotherapy, but it presents several disadvantages such as BCG failure and intolerance. Another way is to use chemotherapy, which is generally better tolerated that BCG. In this case, drugs such as epirubicin, doxorubicin, paclitaxel and gemcitabine are used. Nevertheless, intravesical chemotherapy only prevents recurrence in the short-term. These failings can be partially attributed to the short residence time and low bioavailability of the drug within the upper urinary tract and the cancer cells, resulting in a need for frequent drug instillation. To avoid these problems, biodegradable ureteral stents impregnated by supercritical fluid CO2 (SCF) with each of the four anti-cancer drugs were produced. MATERIAL & METHODS: Four formulations with different concentrations of gelatin and alginate and crosslink agent were tested and bismuth was added to confer radiopaque properties to the stent. The preliminary in vivo validation studies in female domestic pigs was conducted at the University of Minho, Braga, after formal approval by the institutionâ s review board and in accordance with its internal ethical protocol for animal experiments. Paclitaxel, epirubicin, doxorubicin and gemcitabine were impregnated in the stents and the release kinetics was measured in artificial urine solution (AUS) for 9 days by UV spectroscopy in a microplate reader. The anti-tumoral effect of the developed stents in transitional cell carcinoma (TCC) and HUVEC primary cells, used as control, was evaluated. RESULTS: The in vivo validation of this second-generation of ureteral stents performed was herein demonstrated. Biodegradable ureteral stents were placed in the ureters of a female pigs, following the normal surgical procedure. The animals remained asymptomatic, with normal urine flow. The in vitro release study in AUS of the stent impregnated showed a higher release in the first 72h for the four anti-cancer drugs impregnated after this time the plateau was achieved and the stent degraded after 9 days. The direct and indirect contact of the anti-cancer biodegradable stents with the TCC and HUVEC cell lines confirm the anti-tumor effect of the stents impregnated with the four anti-cancer drugs, reducing around 75% of the viability of the TCC cell line after 72h and no killing effect in the HUVEC cells. CONCLUSIONS: The use of biodegradable ureteral stent in urology clinical practice not only reduce the stent-related symptoms but also open new treatment therapyâ s, like in urothelial tumors of upper urinary tract. Furthermore, we have demonstrated the clinical validation in vivo pig model. This study has thus shown the killing efficacy of the anti-cancer drug eluting biodegradable stents in vitro for the TCC cell line, with no toxicity observed in the control, non-cancerous cells.The direct and indirect contact of the anti-cancer biodegradable stents with the TCC and HUVEC cell lines confirm the anti-tumor effect of the stents impregnated with the four anti-cancer drugs, reducing around 75% of the viability of the TCC cell line after 72h and no killing effect in the HUVEC cells. This study has thus shown the killing efficacy of the anti-cancer drug eluting biodegradable stents in vitro for the TCC cell line, with no toxicity observed in the control, non-cancerous cells.

Production and extraction of polysaccharides and oligosaccharides and their use as new food additives

Polysaccharides and oligosaccharides can improve quality and enhance nutritional value of final food products due to their technological and nutritional features ranging from their capacity to improve texture to their effect as dietary fibers. For this reason, they are among the most studied ingredients in the food industry. The use of natural polysaccharides and oligosaccharides as food additives has been a reality since the food industry understood their potential technological and nutritional applications. Currently, the replacement of traditional ingredients and/or the synergy between traditional ingredients and polysaccharides and oligosaccharides are perceived as promising approaches by the food industry. Traditionally, polysaccharides have been used as thickening, emulsifying, and stabilizing agents, however, at this moment polysaccharides and oligosaccharides claim health and nutritional advantages, thus opening a new market of nutritional and functional foods. Indeed, their use as nutritional food ingredients enabled the food industry to develop a countless number of applications, e.g., fat replacers, prebiotics, dietary fiber, and antiulcer agents. Based on this, among the scientific community and food industry, in the last years many research studies and commercial products showed the possibility of using either new or already used sources (though with changed properties) of polysaccharides for the production of food additives with new and enhanced properties. The increasing interest in such products is clearly illustrated by the market figures and consumption trends. As an example, the sole market of hydrocolloids is estimated to reach $7 billion in 2018. Moreover, oligosaccharides can be found in more than 500 food products resulting in a significant daily consumption. A recent study from the Transparency Market Research on Prebiotic Ingredients Market reported that prebiotics' demand was worth $2.3 billion in 2012 and it is estimated to reach $4.5 billion in 2018, growing at a compound annual growth rate of 11.4% between 2012 and 2018. The entrance of this new generation of food additives in the market, often claiming health and nutritional benefits, imposes an impartial analysis by the legal authorities regarding the accomplishment of requirements that have been established for introducing novel ingredients/food, including new poly- and oligosaccharides. This chapter deals with the potential use of polysaccharides and oligosaccharides as food additives, as well as alternative sources of these compounds and their possible applications in food products. Moreover, the regulation process to introduce novel polysaccharides and oligosaccharides in the market as food additives and to assign them health claims is discussed.

Fotoestabilidad de compuestos fenólicos. Evaluación de su potencial capacidad como aditivos antioxidantes. Photostability of phenolic compounds. Assessment of their potential antioxidant activity as additives.

La autooxidación es la forma de deterioro de los productos grasos más importante después de las alteraciones producidas por microorganismos, lo que representa un tema de gran interés económico para las industrias alimenticia y cosmética, ya que da lugar a la aparición de sabores y olores desagradables lo que hace que estos productos sean inaceptables para el consumidor o que reduzcan su vida útil. Dicho proceso se inicia a partir de la reacción de ácidos grasos con oxígeno y puede ser desencadenado por la exposición del producto graso a la luz medioambiental. En estos casos ocurre un proceso de fotooxidación sensibilizada, con la participación de especies reactivas de oxígeno (ROS). Por esta razón, la preservación de producto graso al efecto de las ROS es un punto de capital importancia. Las industrias intentan evitar la oxidación de los productos grasos mediante diferentes técnicas, como el envasado al vacío o en recipientes opacos, pero también utilizando antioxidantes agregados ex-profeso. En particular, los fenoles son secuestradores no enzimáticos de ROS y radicales libres. Actúan como antioxidantes secundarios o interruptores de la cadena oxidativa de lípidos, desactivando las especies reactivas en sus etapas iniciales y evitando que el proceso oxidativo continúe. Por tal motivo, para el presente Proyecto hemos escogido, como potenciales antioxidantes, dos fenoles estructuralmente relacionados con el hidroxitirosol-un antioxidante natural del aceite de oliva-. A través de reacciones fotosensibilizadas, mediante un estudio cinético, mecanístico, de relaciones estructura-reactividad y de dilucidación de fotoproductos se intentará obtener la información que satisface los objetivos específicos de este Proyecto, a saber: a) la resistencia de dHT frente a la oxidación fotopromovida, y en particular a los procesos fotosensibilizados; b) la propensión de dHT para generar especies oxidantes ya sea por irradiación directa o por interacciones específicas con estados excitados de otras moléculas; c) la influencia del medio sobre la capacidad antioxidante de dHT; d) el establecimiento de relaciones estructura-reactividad en lo referida a la actividad antioxidante de dHT. Se trabajará con distintos tipos de sensibilizadores como generadores de diferentes ROS. Para establecer y dilucidar los aspectos cinéticos y mecanísticos mencionados es necesario obtenerinformación acerca de las constantes cinéticas de los diferentes procesos involucrados. La estrategia de trabajo consistirá en abordar condiciones experimentales tales que inhiban determinadas reacciones competitivas y permitan el desarrollo de otras. Se espera que el conocimiento que se genere a partir de los resultados del presente Proyecto, constituya un importante aporte para el diseño y desarrollo de nuevos antioxidantes liposolubles que posean exacerbadas sus propiedades como fotoprotectores frente a eventuales oxidaciones a las que pueda estar expuesto un producto graso.