Sol-gel thin films for corrosion protection

The preparation of sol-gel coatings with specific chemical functions offers potential advantages over traditional methods as it offers tailoring of their structure, texture and thickness and allows the fabrication of large coatings. The chemical protection of 316L stainless steel has been verified for ZrO₂, TiO₂---SiO₂ and Al₂O₃---SiO₂ coatings. The anticorrosion behavior of the films have been characterized in acidic and basic media by weight and loss, electrochemical techniques, XRD and FTIR and SEM spectroscopic techniques. Analysis of the data indicates that the films act as geometric blocking layers against exposure to the corrosive media and increase drastically the lifetime of the substrate (for instance up to 10 for stainless steel).     

Spoilage and shelf life of sardines (Sardina pilchardus) packed in modified atmosphere

The effect of modified atmosphere packing (MAP) (O₂/CO₂/N₂, 5/35/60 (%) and O₂/CO₂/N₂, 5/70/25 (%)) on the quality of sardine stored in refrigerator was investigated in terms of sensory, chemical and microbiological analysis. Although chemical and microbiological analyses indicated that modified atmosphere packing prolonged the shelf life of sardine compared with that of air packing, sensory analysis showed that the extension of shelf life was (condition: O₂/CO₂/N₂, 5/70/25 (%)) 8 days and in air (condition: O₂/CO₂/ N₂, 5/35/60 (%)) 6 days. The results showed significant differences (p <0.05) between air and MAP storage conditions.     

Transxiphoid approach without median sternotomy for the repair of atrial septal defects

BACKGROUND: Interest in minimally invasive procedures has recently increased because it results in less surgical trauma, decreased patient discomfort, short hospital stay, reduced costs, and better cosmetic appearance. Based on these facts, we have been using the transxiphoid process approach without sternotomy for the correction of atrial septal defects. METHODS: From July 1996 to January 1997, the xiphoid process window approach was performed in 10 patients with ostium secundum atrial septal defect. Ages ranged from 6 months to 14 years (mean, 5.3 years). In all patients, extracorporeal circulation was carried out by means of cannulation of the femoral artery and both caval veins and of aortic cross-clamping. Videothoracoscopy was used to improve visualization of the aorta. RESULTS: There were no intraoperative or postoperative complications, and in all but 1 patient, extubation was possible while in the operating room. CONCLUSIONS: The xiphoid process window, with no median sternotomy, permitted closure of the atrial septal defects with good results and could be used as a less invasive technique for their correction.     

A study on the carbonization of grapeseed and chestnut shell

Carbonization experiments of grapeseed and chestnut shell samples having the average particle size of 0.657 mm and 0.377 mm, respectively, were performed to determine the effect of temperature, sweep gas flow rate and heating rate on the biochar yield. A statistical design technique was applied by the use of a two-level factorial design matrix to interpret experimental results. Carbonization conditions were selected according to a two-level factorial design matrix considering the following variables: temperature (723 K and 823 K), nitrogen gas flow rate (0 and 1000 cm³/min) and heating rate (5 and 20 K/min). Empirical relations between the biochar yield and the carbonization conditions were developed. To comment on the effect of parameters between the superior and inferior levels and to prove the accuracy of design equations from statistical design technique, biochar yields obtained at different conditions were also presented in the graphical way. It was found that temperature has the strongest effect on the biochar yields in comparison with nitrogen gas flow rate and heating rate. Biochar yields of grapeseed and chestnut shell were decreased with the increasing temperature, heating rate and sweep gas flow rate. A comparison between the fuel properties of waste materials and biochar products was also done.     

Thermal Residual Stresses in One-Directional Functionally Graded Plates Subjected to In-Plane Heat Flux

This study carries out the transient thermal residual stress analyses of functionally graded clamped plates for different in-plane material compositions and in-plane heat fluxes. The heat conduction and Navier equations representing the two-dimensional thermoelastic problem were discretized using the finite-difference method, and the set of linear equations were solved using the pseudo singular value method. Both in-plane temperature distributions and the heat transfer period were affected considerably by the compositional gradient. The type of in-plane heat flux had a minor effect on the temperature profile, but on the heat transfer period. The high stress levels appeared in the ceramic-rich regions. The normal and equivalent stresses exhibited a sharp change in the plates with ceramic-rich as well as metal-rich compositions, and the concentrated on a narrow ceramic layer. A smooth stress variation was achieved through the graded region with a balanced composition of ceramic and metal-phases, and the stress discontinuities disappeared. The in-plane shear stress was negligible. The equivalent stress exhibited a linear temporal variation for both constant and sinusoidal heat fluxes, but a nonlinear variation for the exponential heat flux. In case the heat flux is applied along the metal edge (metal-to-ceramic plate) instead of the ceramic edge, the displacement and stress components exhibited similar distributions to those of a ceramic-to-metal plate but in the opposite direction. As a result, the distribution of in-plane material composition affects only normal stress distributions, whereas the peak stress levels occur in the ceramic-rich regions. Since the normal stresses concentrate along a narrow ceramic layer for ceramic-rich or metal-rich compositions, a balanced in-plane material composition distribution of ceramic and metal would be useful to avoid probable local ceramic fracture or damage.     

M-hexaferrite–APTES/Pd(0) Magnetically Recyclable Nano Catalysts (MRCs)

Magnetically recovable BaFe₁₂O₁₉–APTES–Pd(0) and SrFe₁₂O₁₉–APTES–Pd(0) catalysts were easily synthesized by immobilizing Pd nanoparticles on the surface of magnetic hexaferrite–NH₂ microspheres. It was found that the combination of BaFe₁₂O₁₉, SrFe₁₂O₁₉ and 3-aminopropyltriethoxysilane (APTES) could give rise to structurally stable catalytic sites. Furthermore, BaFe₁₂O₁₉–APTES–Pd(0) and SrFe₁₂O₁₉–APTES–Pd(0) magnetically recyclable nano catalysts (MRCs) can be recovered by magnet and reused for nine runs for hydrogenation of 4-nitroaniline and dinitribenzene without significant loss in its catalytic activity which shows the indicative of a potential applications of these catalyst in industry.     

Shape engineering vs organic modification of inorganic nanoparticles as a tool for enhancing cellular internalization

ABSTRACT: In nanomedicine, physicochemical properties of the nanocarrier affect the nanoparticle's pharmacokinetics and biodistribution, which are also decisive for the passive targeting and nonspecific cellular uptake of nanoparticles. Size and surface charge are, consequently, two main determining factors in nanomedicine applications. Another important parameter which has received much less attention is the morphology (shape) of the nanocarrier. In order to investigate the morphology effect on the extent of cellular internalization, two similarly sized but differently shaped, rod-like and spherical, mesoporous silica nanoparticles were synthesized, characterized and functionalized to yield different surface charges. The uptake in two different cancer cell lines was investigated as a function of particle shape, coating (organic modification), surface charge and dose. According to the presented results, particle morphology is a decisive property regardless of both the different surface charges and doses tested, whereby rod-like particles internalized more efficiently in both cell lines. At lower doses, whereby the shape-induced advantage is less dominant, however, charge-induced effects can be used to fine-tune the cellular uptake as a prospectively "secondary" uptake regulator for tight dose-control in nanoparticle-based drug formulations.     

Oil prices and current account: A structural analysis for the Turkish economy

Although there has been an increasing number of studies about the effects of oil prices on the macroeconomic performances, the literature on the interaction between oil prices and current account is limited, especially for oil importing developing countries. This paper analyzes the impact of oil prices on the current account balances for the Turkish economy using a structural vector autoregression model. Our model allows us to identify the net effect of oil prices on current account balances after controlling for other factors such as output gap and exchange rate misalignment. The results show that the response of current account ratio to oil price shock increases gradually up to the first three months and then starts to decrease, which indicates a significant effect of oil price shocks in the short-run. Moreover, when the obtained structural shocks are employed in a simple regression analysis, the parameter regarding the oil price shocks is found to be negative and statistically significant. The final section discusses the policy implications of the results.     

Characterization of biochar and bio-oil samples obtained from carbonization of various biomass materials

Apricot stone, hazelnut shell, grapeseed and chestnut shell are important biomass residues obtained from the food processing industry in Turkey and they have a great importance as being a source of energy. In this study, the characteristics of bio-oil and biochar samples obtained from the carbonization of apricot stone, hazelnut shell, grapeseed and chestnut shell were investigated. It was found that the biochar products can be characterized as carbon rich, high heating value and relatively pollution-free potential solid biofuels. The bio-oil products were also presented as environmentally friendly green biofuel candidates.