Journal of Nano Research Vol. 16

Abstract: Many materials with different surfaces have been developed for dental and orthopedics implants. Among the various materials for implants, titanium and bioactive ones such as calcium phosphates and hydroxyapatite, are widely used clinically. When these materials are inserted into bone several biological reactions occur. Thes processes can be associated with surface properties (topography, roughness and surface energy). In this work, ingots were obtained from titanium and molybdenum by using an arc-melting furnace. They were submitted to heat treatment at 1100°C for one hour, cooled in water and cold worked by swaging. Titanium nanotubes were fabricated on the surface of Ti-7,5Mo alloy by anodization, and then treated with NaOH solution to make them bioactive, to induce growth of calcium phosphate in a simulated body fluid. . It is shown that the presence of titanium nanotubes induces the growth of a sodium titanate nanolayer. During the subsequent in-vitro immersion in a simulated body fluid, the sodium titanate nanolayer induced the nucleation and growth of nano-dimensioned calcium phosphate. These titanium nanotubes can be useful as a well-adhered bioactive surface layer on Ti implant metals for orthopedic and dental implants.

Abstract: The structure of Nb3Sn-based, bronze-processed Ti-doped multifilamentary superconducting wires has been studied by TEM and SEM after the first (5750C,100 h) and the second (6500C,100 h) stage of the diffusion annealing. The Nb3Sn layers formation in all the composites proceeds by one and the same mechanism and starts with nucleation of particles and very fine grains of this phase in Nb filaments where Sn diffuses from the bronze matrix. Ti, inserted both in the bronze matrix, or Nb filaments, diffuses into the growing superconducting layer and promotes its more active formation. At the first stage of annealing (5750C, 100 h) Nb3Sn grains have an average size of 40 nm, and at the second stage (6500C, 100 h) they increase by a factor of 1.5 and the grain size distribution gets wider. After the two-stage annealing the amount of the residual niobium is small, and some Nb filaments, especially in doped composites, almost completely transform into Nb3Sn. In the Nb3Sn layers of a zone of columnar grains is adjacent to the residual Nb.

Abstract: An Ag nanoparticle included Glassy carbon (GC)/poly [3, 4-ethylenedioxythiophene] (PEDOT) modified electrode was organized by a straightforward electrochemical method without using any stabilizer or reducing agent. The obtained working electrodes showed a high conductivity when compared to the bare electrode. It also shows superior ability of electrochemically sensing towards the electroreduction of H2O2 with no need for an enzyme or mediator immobilized in the electrode. Under optimum condition the detection limit using chronoamperometry response was estimated to be 0.61 M based on the criterion of signal-to-noise ratio of 3 (S/N of 3).

Abstract: By a single-step supercritical hydrothermal synthesis method, yttrium oxide nanoparticles were successfully prepared without additional treatment. Yttrium oxide nanoparticles were employed as an adsorbent to study the adsorption of some heavy metal ions. This study revealed that nano structure yttrium oxide was an effective adsorbent for removal of lead ions from aqueous solutions.

Abstract: New nanofluids carrier containing fine homogeneous whey protein α-lactalbumin spherical nanoparticles and nanospheres have been synthesized by three methods in this research. Biochemical enzymatic catalysis by V8- protease, chemical hydrolysis (sol-gel assisted self assembly method) using cationic templates and metal ions ligand forming, and also by direct acidic titration method with applying various ethylene glycol derivatives containg alcohol solvents. Repeatability and stability of synthetic nanoparticles and nanospheres milk protein structures in clear and crystalline green water-based nanofluids was confirmed by dynamic light scattering (DLS) analysis and TEM images (2-5nm) even after a one year period of preparation. Fabrication of non-toxic nanosolutions-nanofluids including nonionic and cationic surfactants, cosurfactants and suitable solvents, besides proper incubation temperatures (37-50°C), adjusted aging times and doped of divalent ions–bridging (Ca2+, Mn2+ and Zn2+ ) between specific amino acids and carboxyl groups, are so vital factors in kinetically controlled self-assembly phenomenon of the natural protein building blocks to form high resistant and homogeneous nanoparticles and nanospheres in transparent and clear green nanofluids. Such nanofluids can have many applications in food and pharmaceutical industries for example in formulate foods with high nutritional value in oral and digestive (ingestion) routes, and drug delivery. Interesting textures of SEM images have also shown these new nanobiostructures of natural milk protein morphologies.

Abstract: Undoped ZnO and 0.5−5.0 at.% Sn-doped ZnO nanoparticles were synthesized by flame spray pyrolysis (FSP) using zinc naphthenate and tin (II) 2-ethylhexanoate dissolved in xylene as the precursors under a 5/5 (precursor/oxygen) flame condition. UV-Vis absorption characteristics of the samples were investigated for understanding and relating with the physiochemical characteristics in photocatalytic applications. Kinetic analyzes indicated that the photodegradation rates of phenol could be approximated as pseudo-first-order and zero-order kinetics in the case of undoped ZnO and Sn-doped ZnO nanoparticles respectively, according to the Langmuir-Hinshelwood model. The effect of Sn doping revealed the deterioration of the phenol photodegradation performance over ZnO-based catalysts, possibly due to the formation of a deep state in the ZnO band gap energy.

Abstract: Titanium dioxide thin films have been prepared by the sol–gel dip-coating method on an ITO substrate. The samples obtained were characterized by different experimental techniques: XRD, Raman, FTIR, spectroscopy of the electrochemical potential and SEM. The X-ray diffraction results showed that the TiO2 thin film obtained for a layer, after a temperature of annealing (400°C) and at the speeds of steeping between 2 and 10 cm∙s-1 was amorphous, and transformed into anatase–brookite at 0.6 cm∙s-1 for 400°C. The data of Raman spectroscopy is in good agreement with the DRX results. Observation by scanning electron microscope shows that the coating was transparent and homogeneous without any visual cracking over a wide area, and the increase in the treatment temperature did not affect the uniformity of the film. The interface of our layers to behaved like a n-type semiconductor.

Abstract: We report on an experimental study on transparent nanoporous titanium oxide films on glass substrates using an anodization process. Ti thin films of 50-90 nm have been deposited on glass substrate by dc sputtering (1.8210-3 Pa, 100 W) followed by a thermal treatment of 500°C for 30 min. in order to improve the adhesion to the glass substrate. Then an anodization process was applied in order to obtain TiO2 thin nanoporous layers using a cell consisted of three electrodes and aqueous electrolyte solution of 1% NH4F concentration, monoethyleneglycol and DI water. After anodization the samples were annealed at 450°C for 45 min using nitrogen gas. The layers have a nanoporous structure with pore dimensions in the range of 50-80 nm. FTIR and micro-Raman spectroscopy were used to identify the crystalline phase of the TiO2 layers. Raman scattering spectra clearly identify the anatase phase on the basis of Eg modes at ~ 146 cm-1 of the TiO2. The FTIR spectrum showed only the peak at 614 cm−1 which can be associated with the characteristic vibrational mode of TiO2 anatase. The optical properties of TiO2 thin films have been determined by ellipsometric measurements in the spectral range (0.2-0.8 μm) and a value of 2.41-2.45 was obtain for refractive index at 632 nm. Spectrophotometric measurements showed a transmittance over 70% and an optical band gap of 3.3-3.5 eV was determined.

Abstract: Ammonia production is a capital-intensive industry as it requires high temperature (400-500oC) and also high pressure (150-300 bar) for its daily operations. An earnest effort was made to synthese ammonia gas using an in-house designed microreactor. The production of ammonia was carried out in a magnetic field reaction zone, with the reaction temperature of 30°C - 280°C and ambient operation pressure. Mn0.8Zn0.2Fe2O4 nanoparticles, synthesized using the sol gel method, were used as the catalyst for the ammonia synthesis. XRD confirmed the single phase ferrites and FESEM images revealed nanofibre-like morphology when sintered at 700oC in argon gas. Electron diffraction was performed using HRTEM and obtained diffraction patterns confirmed the crystal structure of the catalyst. By using the Kjeldahl method it was found that the reaction carried out in 1 Tesla magnetic field gave approximately 46% ammonia yield. The proposed new method could be appealing for ammonia manufacturers due to highly economical implication which may offer urea producers a potential contender in the competitive market place.

Abstract: Using various electron microscopy techniques, we have demonstrated that resistance of enamel and dentin to acid attack could be increased in an acid-base resistant zone which was formed following the application of some acidic monomers, especially phosphoric-acid ester methacrylates incorporated into a few self-etching dental adhesives. We proposed that the diffusion of such acidic monomers beyond the classic hybrid layer (interfacial zone) and their ion-exchange interactions with the available hydroxyapatite could result in formation of stable organic-inorganic complexes, and that the structures should be termed “super tooth”, as they would in concept withstand major causes of dental caries and tissue degradation. We also reported that the fluoride-release from these biomaterials could contribute to reinforcement of the underlying tissue. On mechanical testing methodology, we demonstrated that time-dependent nanomechanical response of dental structures in nanoindentation could provide useful information that may not be derived under large-scale fracture experiments such as the common bonding tests. In the present paper, we present some of our recent findings on the ultra-morphological and nanomechanical characteristics of super enamel and super dentin created by self-etching adhesives, compared with sound tissue and the tissue bonded by conventional adhesives following phosphoric-acid treatment or etch-and-rinse adhesives.