Rectification of Oblique Cracks in Fracture Toughness Testing

A technique for rectification of oblique crack fronts is described. It involves out-of-plane bending fatigue loading of the specimens. The method can be valuable in cases when residual stresses or other causes precludes a straight crack front being produced by standard fatigue loading in the process of preparing specimens for fracture toughness testing. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis and Evaluation of Novel Functional Polymers Derived from Renewable Jasmine Lactone for Stimuli-Responsive Drug Delivery

Instances of synthetic polymers obtained from renewable feedstock with the possibility of post-synthesis functionalization are scarce. Herein, the first ever synthesis and drug delivery application of amphiphilic block copolymer (mPEG-b-PJL) derived from renewable jasmine lactone with free allyl groups on the backbone is presented. The polymer is synthesized via facile ring-opening polymerization and subsequently, UV mediated thiol-ene click chemistry is utilized for post-functionalization. The introduction of hydroxyl, carboxyl, and amine functionality to mPEG-b-PJL polymer is successfully established. As a proof-of-concept demonstration, doxorubicin (DOX) is conjugated on hydroxyl-terminated polymer (mPEG-b-PJL-OH) via redox responsive disulfide linkage to obtain PJL-DOX. PJL-DOX is readily self-assembled into micelles with an average hydrodynamic size of ≈ 150 nm and demonstrates reduction-responsive DOX release. Micelles are evaluated in vitro for cytocompatibility and selective drug release in cancer cells (MDA-MB-231) using 10 mm glutathione as a reducing agent. Cytotoxicity and microscopy results confirm a redox-triggered release of DOX, which is further confirmed by flow cytometry. The introduction of these novel functional polymers can pave the way forward in designing polymer-drug conjugate-based smart nano-carriers.     

Influence of shallow and deep cryogenic treatment on the corrosion behavior of Ti6Al4V alloy in isotonic solution

This study investigated the corrosion behavior of cryogenically treated Ti6Al4V alloys in an isotonic solution. Samples were subjected to shallow or deep cryogenic treatment, and some samples then underwent an aging procedure. They were characterized by microstructural analysis, an open circuit potential test, an electrochemical impedance method, and a potentiodynamic test. The polarization tests demonstrated that the deep cryogenic treatment shifted the corrosion potential to more anodic values compared to the untreated sample. For all treated samples, it was found that the corrosion current densities were lower than those in the untreated sample, and the lowest current densities were registered for the sample subjected to deep cryogenic treatment for 36 hr. The shallow cryogenic treated samples and the sample aged without cryogenic treatment showed semicapacitive loops with poor corrosion impedance compared to the untreated sample, whereas deep cryogenic treatment produced Warburg impedance with diffusion in the solid phase.     

Application of Radial Basis Function Networks with Feature Selection for GDP Per Capita Estimation Based on Academic Parameters

In this work, a system based on Radial Basis Function Network was developed to estimate Gross Domestic Product per capita. The data set based on 180 academic parameters of 13 Organisation for Economic Co-operation and Development countries was used to verify the effectiveness and accuracy of the proposed method. Gross Domestic Product per capita was studied to be estimated for the first time with academic parameters in this study. The system has been optimized using feature selection method to eliminate unimportant features. Radial Basis Function network results and Radial Basis Function network with feature selection method results were compared. The findings show that the Radial Basis Function network with feature selection is 10% more successful than the Radial Basis Function results. Based on results, this methodology can be applied in applications of Gross Domestic Product per capita forecasting.