Synthesis And Characterization Of 3D-Printed Functionally Graded Porous Titanium Alloy

This study aims to 3D print titanium alloy constructs incorporating gradient of porosities, from the fully dense core to the porous outer surface. Gradient porous specimens were prepared using selective laser melting (SLM). Fully dense specimens fabricated by SLM were used as the control group. Characterization of samples was done using X-ray tomography, uniaxial compression testing, and optical and scanning electron microscopes. The biocompatibility of fabricated samples was investigated using human periodontal ligament stem cells via assessment of cell attachment, viability, and proliferation by direct and indirect assays. The data were analyzed using ANOVA and Tukey’s post hoc test. Characterization of constructs reveals interconnected gradient porosities and higher contact angle in porous samples. The introduction of porosity leads to a significant decrease in compression strength. However, Young’s modulus of the samples with gradient porosity was more similar to the natural bone modulus. The surface microstructure consists of loosely bonded spherical particles. Biocompatibility of the dense and porous samples is appropriate. Although the porosity size led to a reduced cell proliferation rate in the gradient sample, the extract of the gradient sample results in more cell proliferation than the dense sample’s extract. The study demonstrates that a biocompatible functionally graded porous titanium structure can be well fabricated by SLM, and this structure leads to a good match of Young’s modulus to that of the bone

Sitagliptin ameliorates the progression of atherosclerosis via down regulation of the inflammatory and oxidative pathways

Back ground: Atherosclerosis is the major cause of death. The most common risk factors are hyperlipidemia, diabetes, and other factors like chronic infection and inflammation. Objective: This study was undertaken to assess the effect of sitagliptin on atherosclerosis via interfering with inflammatory and oxidative pathways. Materials and Methods: A total of 18 local domestic male rabbits were included in this study. The animals were randomly divided into three groups (6 rabbits in each group): Group I normal were fed with chow (oxiod) diet for 12 weeks. Group II were fed with 1% cholesterol enriched diet for 12 weeks. Group III rabbits fed with cholesterol enriched diet for 6 weeks, and then continued on cholesterol enriched diet and treated with sitagliptin 125 mg/kg/day orally for the next 6 weeks. Blood samples were collected at the start of the study, at 6 weeks of the study and then at the end of treatment to measure serum lipids profile, hsCRP and TNFα. At end of the study, the aorta was removed for measurement of MDA, glutathione and, aortic intima-media thickness. Results: Sitagliptin results in a significant reduction (p < 0.05) in serum level of total cholesterol (TC), triglycerides (TG), high sensitive C-reactive protein (hsCRP) and TNFα with a significant increase (p < 0.05) in serum HDL level. There was a significant reduction (p < 0.05) in aortic MDA, in comparison to the untreated control group. Furthermore, sitagliptin causes significant increment (p < 0.05) in aortic GSH in comparison to induced untreated group. Regarding histopathological results, sitagliptin results in a significant reduction (p < 0.05) in atherosclerotic lesions in comparison to the induced untreated group and significant reduction in aortic intima-media thickness (p < 0.05). Conclusion: Sitagliptin reduced atherosclerosis progression in hyperlipidemic rabbit via its effect on lipid parameters and interfering with inflammatory and oxidative stress

An improved performance of the corona-fractal textile antenna using an inverse patch medium-defected ground-structure technique

Abstract The paper presents the design and analysis of a corona-shaped fractal antenna with a defected ground structure (DGS) for wireless applications. The fractal concept with an inverse patch medium DGS (IPM-DGS) technique is proposed and applied to achieve multi-band frequencies with a high efficiency. The same structure on the top face of the antenna is used as the ground face in an inverse medium. Resulting in the same corona-fractal structure as the DGS. The overall dimension of the antenna is 55mm x 55mm (0.48λ × 0.48λ at the lowest resonant frequency) and is designed on a felt substrate to operate at 2.62 GHz, 3.02 GHz, 3.35 GHz, 3.5 GHz, and 3.62 GHz. The maximum gains of 4.06 dBi and 5.13 dBi with efficiencies of 82% and 80 % are observed at 2.62 GHz and 3.02 GHz, respectively, making the proposed antenna potentially suitable for wearable WBAN/WLAN applications

Bio-functionalized hollow core photonic crystal fibers for label-free DNA detection

Bio-functionalization of inner surfaces of all silica Hollow Core-Photonic Crystal Fibers (HC-PCF) has been investigated. The approach is based on layer-by-layer self-assembly Peptide Nucleic Acid (PNA) probes, which is an oligonucleotide mimic that is well suited for specific DNA target recognition. Two kinds of HC-PCFs have been considered: a photonic Bragg fiber and a hollow core (HC-1060) fiber. After spectral characterization and internal surface functionalization by using PNA probes, genomic DNA solutions from soy flour were infiltrated into the fibers. The experimental results indicate that hybridization of the complementary strand of target DNA increases the thickness of the silica layer and leads up to the generation of surface modes, resulting in a significant modulation of the transmission spectra. Numerical analysis confirms such behavior, suggesting the possibility to realize biological sensing. © 2014 SPIE