Effects of Nano-Materials on Gas and Liquid Permeability in Wood and Nano-Materials
As a naturally regenerated and biodegradable material, wood and wood composites will be deteriorated in nature. Different poisonous materials, called wood preservatives, are therefore forced into the texture of wood and wood composites to prevent the attack of biological deteriorating agents. Moreover, their hygroscopic property causes absorption of water and water droplets, and even the vapor in the air by the hydroxyl groups in the cell-wall polymers; this process of water absorption would eventually result in dimensional instability and deformation of shape. Water absorption and thickness swelling of wood composites, as their main shortcomings, are also closely correlated to their permeation towards the transfer of different liquids and gases. The susceptibility of woody materials against fire hazards also causes immense losses to both life and property, making it necessary to impregnate wood with fire-retardants. The porous structure and permeability of solid wood species is also practically important for drying wood. Improvement in the permeability of wood, as a porous media, is therefore vital to improve its biological resistance against wooddeteriorating agents, consequently increasing its service life, to improve its dimensional stability, and to increase its fireretardancy. Based on the above mentioned facts, it can be concluded that permeability is a physical property that affects preparation and treatment of solid woods and wood composites, as well as many of their final applications. Over decades, different preservatives and fire-retardants were introduced to wood industry, overcoming many of the above mentioned disadvantages. The increased specific surface area resulted from the breaking down of materials to nano-scale provides more effectiveness of their properties. The present study tries to shortly sum up some of the latest research and projects on the effects of impregnation and/or treatment of wood and wood composites with different nanomaterials on the gas and liquid permeability to overcome some of the above mentioned shortcomings.
Calcium Phosphate Nanoparticles and their Biomedical Potential
Nanodimensional and nanocrystalline calcium phosphates (in the form of apatites) of a biological origin are the basic inorganic building blocks of bones and teeth of mammals. The application and potential use of calcium phosphates for clinical repair of damaged bones and teeth to controlled drug delivery devices, multi-modal imaging, and bone regeneration is gaining importance. Calcium phosphate nanoparticles are rigid, biocompatible, biodegradable, bioactive, resorbable and non-immunogenic. Nanostructured calcium phosphates with various morphologies including spherical nanoparticles, plate-like nanocrystals, nano-needles, whiskers/ fibers/wires, mesoporous, nanotubes, nano-blades, and powders with three-dimensional structures have been synthesized by various methods including mechanochemical synthesis, reverse microemulsion, hydrothermal approach, co-precipitation, spraydrying technique, in-situ deposition technique, wet chemical precipitation, gas phase ablation and biomimetic coating. Nanostructured calcium phosphates are promising biomaterials for applications in biomedical areas, such as tissue engineering scaffolds, drug/gene delivery systems, vaccine adjuvants, contrast agents for imaging and multi-modal imaging, nanosystems for photodynamic therapy and antifungal/antibacterial agents.
Effect of Zn Substitution on the Characterization of Cobalt Ferrite Nano Particles Prepared Co-precipitation Method
Nano-crystalline zinc-substituted cobalt ferrite powders, Co1-xZnxFe2O4 (X=0.0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1.0), have been synthesized by the Co-precipitation method. The structural and magnetic properties of the products were determined and characterized in detail by X-ray diffraction (XRD), High Resolution -Transmission Electron Microscope (HR-TEM), Fourier Transform Infrared (FTIR) and vibrating sample magnetometer (VSM). X-ray analysis showed that the samples were cubic spinel. The increase in zinc concentration resulted in an increase in the lattice constant, X-ray density, ionic radii, the distance between the magnetic ions and bond lengths on tetrahedral sites and octahedral sites of cubic spinel structure. The HR-TEM and XRD shows that crystallite size within the range of 6–24 nm. The FTIR measurements between 400 and 2000 cm-1 confirmed the intrinsic cation vibrations of the spinel structure. The variation of saturation magnetization (Ms) value of the samples and Magnetic coercivity were studied. The magnetic measurements show that the saturation magnetization and coercivity decrease by increasing the zinc content. Furthermore, the results reveal that the sample with a chemical composition of Co0.3 Zn0.7Fe2O4 exhibits the super-paramagnetic behavior.
Antitumor Efficiency of Doxorubicin Loaded in Liposomes and Poly Ethylene Glycol Coated Ferrofluid Nanoparticles
Objective: The purpose of this study is to evaluate the antitumor effect of doxorubicin (Dox) after loading in liposomes and PEG coated iron oxide fluidized magnetic nanoparticles (ferrofluids or FMNP). Methods: Liposomal Dox was prepared from phosphatidylcholine (PC) and characterized by ncapsulation efficiency, particle size and zeta potential. On the other hand, the prepared FMNP, coated by PEG and loaded by Dox, were characterized by magnetism, morphology, particle size and stability. FTIR was carried out to study Dox interaction with both delivery systems. The antitumor activity of loaded Dox was investigated for the tumor size, survival assay and histopathological examination of the tumor specimen and then compared to free Dox. Animals injected by Dox loaded FMNP were further subjected to external magnetic field. Results: Liposomal Dox showed encapsulation efficiency of 84 ± 4.5 %. They had an average size of 199.2 ± 54.35 nm and a zeta potential of -44.3 ± 9.17 mV. The prepared FMNP showed roughly spherical shape, with an average size of 17.61351 ± 3.09 nm, which decreased after loading with Dox to 9.33314 ± 1.7984 nm. It was found that, each 800 μL of FMNP can be saturated with 0.1 μg Dox before which, the amount of loading was increased gradually; however, the loading was decreased after 1 h. FTIR revealed the absence of any interaction between Dox and lipid. Liposomal Dox and FMNP loaded Dox (subjected to external magnet) showed an enhancement of 100% and 83.33%, respectively, in the survival assayand 80% and 90%, respectively, for the tumor necrosis index. Conclusion: Liposomes and FMNP (with an external electromagnetic field) have increased the intratumoral accumulation of Dox and hence increase the chemotherapeutic bioavailability.
Preparation, Structural and Electrical Properties of Tin Oxide Nanoparticles
Tin Oxide (SnO2) nanoparticles were synthesized by the wet chemical method. The synthesized nanoparticles were characterized by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), UV analysis and dielectric studies. The crystalline nature and particle size of the samples were characterized by Powder X-ray diffraction analysis (XRD). The morphology was confirmed by scanning electron microscopy (SEM) analysis. The optical properties were obtained from UVVis absorption spectrum. Dielectric studies were carried out for the pelletized SnO2 nanoparticles. The variation of the dielectric constant and dielectric loss were studied. The dielectric constants of the SnO2 nanoparticles are high at low frequencies, and decrease rapidly when the frequency is increased.