Revista de Ciências e Engenharia de Materiais

Pectin and Chitosan are the naturally occurring polymers which possess various beneficial properties. Pectin and Chitosan are abundantly available versatile polysaccharides with wide range of applications. The inherent properties of Pectin and Chitosan could be exploited to develop a biocomposite material which can be used as wound dressing material. Pectin is generously available in plant materials mainly citrus fruit peel. In th[e present study, Pectin was extracted from orange peels by Citric Acid and Alcohol Precipitation method as this method retains the Pectin properties and increases the yield of Pectin extraction. Characterization of Pectin extract by solubility tests and SEM analysis revealed the presence of Pectin. The extracted Pectin is sufficient enough to enhance the gelling ability of the biocomposite material. The extracted Pectin along with Chitosan extra pure was used for development of Pectin Chitosan biocomposite materials with the help of suitable solvents. The biocomposite material was prepared by using lactic acid or glycerol by solvent casting method. The biocomposite material was further characterized by SEM analysis which revealed that the surface of the material was smooth and heterogeneous. Also, antibacterial test against Bacillus subtilis confirms that the Pectin and Chitosan retains its antibacterial property in biocomposite materia.

Alternative small diameter vascular grafts are needed for patients that require surgical revascularization in patients lacking autologous vein. In this study, a Polyglycolic Acid (PGA)-Thermoplastic Polyurethane (TPU) electrospun scaffold seeded with human dermal fibroblasts was placed in a biomimetic perfusion system to generate a hybrid tissue engineered vessel. The outer layer was an electrospun PGA that was co-electrosprayed with sacrificial polyethylene oxide (PEO) microparticles to increase porosity. The PGA-TPU scaffold remained static for 1 week, then circumferential strain amplitude was incremented from 1% to 5% over 6 weeks. The hybrid tissue engineered vessel had an outer cellular layer with collagen deposition replacing the biodegradable PGA and the inner residual polyurethane layer remained relatively acellular. The tensile properties of the hybrid tissue engineered vessel demonstrated a significant reduction in the elastic modulus compared to the PGA-TPU scaffold, but the ultimate tensile strength, extension to break, and burst pressure remained stable. Fouriertransform infrared spectroscopy confirmed the degradation of the PGA and a reduction of polyurethane crosslinking in the hybrid TEV compared to the PGA-TPU. Thus, a biomimetic perfusion system can be used to evaluate the biocompatibility of an electrospun polyurethane scaffold in vitro, to understand the mechanical changes of the polyurethane scaffold after exposure to circumferential stretch, and to generate a hybrid tissue engineered vessel with suitable characteristics for implantation.

Today, polymer composites are almost used in all areas of life. Their light weight, strength, low price and fast processing properties open new ways to their use. In this study, design and structural analysis of a short glass fiber reinforced polyamide involving drastic loadings and functioning environments is presented for a washing machine drum support. The results show that at least 50% short glass fiber reinforcement is needed for a successful material conversion from an Aluminum alloy.

A series of alloy systems take place in class of advanced smart materials with adaptive properties and stimulus response to the external changes. Shape memory alloys take place in this group, due to the shape reversibility and capacity of responding to changes in the environment. These alloys exhibit a peculiar property called shape memory effect, which is characterized by the recoverability of two certain shapes of material at different temperatures. These alloys have dual characteristics called thermoelectricity and super elasticity, from viewpoint of memory behavior. Two successive structural transformations, thermal and stress induced martensitic transformations govern shape memory phenomena in crystallographic basis. Thermal induced martensite occurs along with crystal twinning in self-accommodating manner on cooling and ordered parent phase structures turn into twinned martensite structures, and twinned structures turn into the detwinned structures by stressing material in low temperature condition by means of stress.

Ion-selective membranes, as used in potentiometric sensors, are mixtures of a few important constituents in a carefully balanced proportion.
The changes of composition of the ion-selective membrane, both qualitative and quantitative, affect the analytical performance of
sensors. Different constructions and materials applied to improve sensors result in specific conditions of membrane formation, in
consequence, potentially can result in uncontrolled modification of the membrane composition. Clearly, these effects need to be considered,
especially if preparation of miniaturized, potentially disposable internal-solution free sensors is considered. Furthermore, membrane
composition changes can occur during the normal operation of sensors—accumulation of species as well as release need to be taken into
account, regardless of the construction of sensors used. Issues related to spontaneous changes of membrane composition that can occur
during sensor construction, pre-treatment and their operation, seem to be underestimated in the subject literature. The aim of this work is
to summarize available data related to potentiometric sensors and highlight the effects that can potentially be important also for other
sensors using ion-selective membranes, e.g., optodes or voltammetric sensors.

Huge amounts of unusable portion of leather and cattle hair from leather industries and chicken feather from poultries are polluting the environmental atmosphere tremendously. To reduce environmental pollution, these discarded parts need to use to produce other products. In this research, cow hair, chicken feather and waste leather were used to prepare useful composites combining with unsaturated polyester resin (UPR) to consider their reinforcement property and chemical property with view to curtail the environmental pollution. One portion of washed fibers was treated with aqueous solution of sodium hydroxide and the left portion was untreated. Then the chemically treated and untreated both portions of fibers were used to unsaturated polyester resin at 2, 5, 7, 10, 12 and 15 wt% fiber loading respectively. The composites were produced by hand lay-up technique and prepared composites were characterized by tensile and bending properties, Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM) and Thermo Gravimetric Analysis. Obtained all the results revealed best outcomes and significant enhancement in the properties of the composites with the optimum combination by 5 wt% treated cow hair fiber.

Smart materials are materials that have intrinsic sensing, controlling, actuation or information processing capabilities in their microstructures. These materials are used to create smart systems containing multifunctional parts that can perform sensing, control, and actuation. Smart systems often exhibit high functionality such as self-diagnosis and self-restoration. Smart materials are being developed for applications in numerous manufacturing sectors such as in the aerospace industry, biomedical industry, and general manufacturing industries. This review paper covers some of the recent advances in the area of smart materials and the enhanced functional capabilities these materials provide for a range of smart applications.

Ceria particles of nanodispersed composition have been obtained by laser ablation and subsequent treatment in an aqueous solution. Using techniques (TEM, XRD, Raman, EELS) of the nanostructural and electronic analysis, it is shown that the produced particles have structural defects that stabilize their internal structure. It is established that when the particle size decreases from 100 to 10 nm, the crystal lattice parameter lowers from 5.41 to 5.39 , and the elemental O/Ce composition changes from 1:1.83 to 1:1.76. The ablated CeO2 particles of nanodispersed composition exhibit high antioxidant activity due to the high concentration of functional defects on the surface of nanoparticles.