Elastic response of functionally graded circular plates under a drop-weight

The three-dimensional impact behaviours of functionally graded (FG) circular plates were studied under a drop-weight. The functionally graded circular plate was composed of ceramic (SiC) and metal (Al) phases and the through-thickness mechanical properties through the region between the metal and ceramic layers vary continuously according to a power-law distribution of the volume fraction of the ceramic. The through-thickness material properties of the FG circular plate were determined using the Mori–Tanaka scheme. The effects of layer number and compositional gradient exponent as well as impactor velocity and plate radius on the elastic impact response of the FG circular plates were investigated. The compositional gradient exponent, impactor velocity and plate radius played an important role on the impact response of the FG circular plates, whereas the layer number through the plate thickness had a minor effect. In addition, the failure strains in all layers were determined using Tamura–Tomota–Ozowa (TTO) model in order to predict the damage regions in each layer through the thickness of FG circular plates.     

Characterization and dual functionalization of polystyrene with propionic anhydride and cyanate derivatives

First, Friedel–Crafts reactions were used for the acylation process. For this, polystyrene (PS) was reacted with propionic anhydride in the presence of Lewis acid catalyst. The amount of acyl group linked PS as a result of acylation has been identified as volumetric. Second, the bromination and lithiation reactions of acylated PS containing carbonyl groups were realized. Also, the lithiated PS containing acyl groups has been modified a second time with various isocyanates and isothiocyanate derivatives in the presence of n?BuLi catalyst. Some important reaction parameters were assigned in order to optimize the process. The structure all of the products were characterized by Fourier transform infrared, ¹H NMR (Proton Nuclear Magnetic Resonance), and thermogravimetric methods. In addition, reaction yields were determined according to the result of elemental analysis. Dual functionalization yields were realized between 62.2% and 69.9%. For kinetic analysis, the TG/DTG (Thermal Gravimetric Analysis/Differantial Thermal Analysis) data obtained at three different heating rates were processed by Kissinger–Akahira–Sunose method. The results demonstrated that the acylation reaction, bromination and lithiation reactions, and dual functionalization reactions with cyanate derivatives can be carried out to obtain a significantly functionalized polymer. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1351‐1362, 2013     

Investigation of Tribological Properties and Characterization of Borided AISI 420 and AISI 5120 Steels

In the present study, tribological and characterization properties of borides formed on AISI 420 martensitic stainless and AISI 5120 cementation steels have been investigated. The boride layer was characterized by optical microscopy, X-ray diffraction technique and the micro-Vickers hardness tester. X-ray diffraction analysis of boride layers on the surface of the steels revealed the existence of FeB, Fe₂B and CrB compounds. The wear tests were carried out in a ball-disc arrangement under a dry friction condition at room temperature with an applied load of 10 N and with a sliding speed of 0.3 m/s at a sliding distance of 1,000 m. The wear surfaces of the steels were analyzed using a SEM microscopy and X-ray energy dispersive spectroscopy EDS. The results were compared with each other. It was observed that the friction coefficient of unborided and borided steels ranged from 0.42 to 0.63. The wear rate of the borided steels was found to be approximately five times lower the wear rate of the unborided steels.     

Universal filter with three inputs using CCII+

A voltage-mode universal filter with three inputs and one output using only plus-type current conveyors (CCII+) is presented. This circuit uses three CCII+s, three resistors and a minimum number of capacitors. It has low sensitivity, low output impedance and low component spread. The use of only CCII+s simplifies the configuration     

CFA based fully integrated nth-order lowpass filter

A general synthesis procedure for the realisation of an nth-order lowpass voltage transfer function by a fully integrated circuit is presented, and a CFA based fully integrated nth-order filter which uses (n) CFA based integrators and only grounded capacitors is given. This circuit is especially suitable for monolithic implementation     

A rare cause of abdominal pain: Catheter in the middle hepatic vein

Hemodialysis catheters are vital for chronic renal failure patients. Permanent tunneled dialysis catheters may be inserted through the jugular, subclavian, and femoral veins. In this paper, we aimed to present the computed tomography findings of a chronic renal failure patient who had referred our clinic with abdominal pain and dyspnea symptoms. This patient had a formerly inserted hemodialysis catheter for chronic renal failure and her catheter was found to be extending towards the middle hepatic vein with the tip leaning onto the parenchyma. Hemodialysis catheters can provide instant vascular access and can also be used for the consecutive procedures. Permanent hemodialysis catheters are ideal for long‐term use when placing an arteriovenous fistula is contraindicated or is no longer possible under conditions like advanced heart failure, peripheral artery disease or short life expectancy. The internal jugular, subclavian, the femoral veins, and the inferior vena cava can be used for catheter insertion. The tip of the catheters inserted in the neck or the thorax must extend to the vena cava superior. Catheter malposition may both lead to fatal outcomes and ineffective dialysis. It is important to obtain chest X‐rays after the procedure, particularly to detect catheter malposition.     

Wear Resistance and Characterization of Borided Ni-Based Alloys

Powder Metallurgy and Metal Ceramics - In this study, nickel-magnesium (Ni–Mg) alloys with a 97% Ni–3% Mg compositions were successfully borided with packet boriding at temperatures...     

Combined effect of a plasticizer and carvacrol and thymol on the mechanical,thermal, morphological properties of poly(lactic acid)

In this study, the effects of the monotherpenic phenol concentration on the properties of biocomposites containing plasticized poly(lactic acid) (PLA) with acetyl tributyl citrate (ATBC) were investigated. The monotherpenic phenols carvacrol (C) and thymol (T) were added to PLA by a melt‐blending method. The prepared samples were characterized by means of tensile testing, Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy (SEM), and antibacterial activity tests. The addition of ATBC to PLA resulted in hydrogen bonding between ATBC and PLA. We observed that ATBC, C, and T reduced the glass‐transition temperature of PLA. The presence of C and T decreased the maximum degradation temperature slightly. Because of the plasticization effect of the additives, the tensile strength and Young's modulus of PLA decreased, whereas the extent of elongation they experienced before failure increased. This effect was also observed with SEM analysis in terms of plastic deformation at break. The antibacterial activity tests showed that samples containing high concentrations of C demonstrated an improved antibacterial activity against Staphylococcus aureus, Salmonella typhimurium, and Listeria monocytogenes bacteria. We observed that C exhibited a higher inhibition against bacterial strains than T. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45895.     

Acceptor formation in Mg-doped,indium-rich GaxIn1?xN: evidence for p-type conductivity

We report on the Mg-doped, indium-rich Ga_xIn_1−xN (x < 30). In the undoped material, the intrinsic electron density is very high and as a result there is no detectable photoconductivity (PC) signal within the range of temperatures of 30 <T < 300 K. In the Mg-doped material however, where the conductivity is reduced, there is a strong PC spectrum with two prominent low-energy peaks at 0.65 and 1.0 eV and one broad high-energy peak at around 1.35 eV. The temperature dependence of the spectral photoconductivity under constant illumination intensity, at T > 150 K, is determined by the longitudinal-optical phonon scattering together with the thermal regeneration of non-equilibrium minority carriers from traps with an average depth of 103 ± 15 meV. This value is close to the Mg binding energy in GaInN. The complementary measurements of transient photoluminescence at liquid He temperatures give the e-A⁰ binding energy of approximately 100 meV. Furthermore, Hall measurements in the Mg-doped material also indicate an activated behaviour with an acceptor binding energy of 108 ± 20 meV.