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This work aims to study the effect of mechanical treatment technique on titanium coated with PVD for the enhancement of corrosion resistance for the biomedical implant. First, substrates were coated with TiN via PVD then applied the mechanical treatment through ultrasonic vibration. Results show that all coated samples treated with ultrasonic vibration improve the surface of the coated sample and produce a compact coating as compared with a substrate coated without mechanical treatment. The corrosion test evaluated by Potentiodynamic polarization and Electrochemical Impedance Spectroscopy indicated that all coated samples treated with mechanical treatment showed high corrosion resistance as compared with the untreated sample. It can be concluded that mechanical treatment which is a simple technic can be used as an alternative to improve the corrosion resistance thus reduce the implant and manufacturing cost for biomedical applications.

Feeding electivity was investigated in a non-outbreaking population of the crown-of-thorns starfish Acanthaster planci (L.) from North Sulawesi, Indonesia. A null model-based approach was used to assess the feeding pattern of Acanthaster in relation to the availability of coral prey in the field. Of a total of 70 species of corals recorded as prey, massive species, particularly of Faviidae, tended to be more frequently consumed than would be expected under the assumption of random feeding by A. planci. Branched and encrusting/laminar forms of corals that occurred in relatively exposed sites were apparently not preferred, pointing to the importance of non-acroporan massive species of corals in cryptic habitats as prey for A. planci. The null model-based electivity index Z introduced here directly measured the deviation from random feeding, while two common indices (Ivlev's and Vanderploeg and Scavia's) only partially reflected such deviations (hence, prey selection cannot be accurately demonstrated by these). Electivity values (Z) for poritid species and Acropora palifera, the most common Acropora species in the study site, were significantly negative, indicating apparent avoidance of them by Acanthaster. Our results indicate that accessibility to different coral species and the choice/avoidance of certain species are the important elements of feeding in non-outbreaking populations of Acanthaster inhabiting spatially variable reef environments. A similar consideration may apply to the feeding patterns of other corallivores that possess superior/inferior mobility to Acanthaster. The present study emphasizes the merit of testing the observed patterns, using null models for a rigorous assessment of feeding preferences.

Cuprous oxide (Cu2O) thin films were deposited onto indium tin oxide (ITO) coated glass substrate by sol-gel spin coating technique using different additives, namely, polyethylene glycol and ethylene glycol. It was found that the organic additives added had a significant influence on the formation of Cu2O films and lead to different microstructures and optical properties. The films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and ultraviolet-visible spectroscopy (UV-Vis). Based on the FESEM micrographs, the grain size of film prepared using polyethylene glycol additive has smaller grains of about 83 nm with irregular shapes. The highest optical absorbance film was obtained by the addition of polyethylene glycol. The Cu2O thin films were used as a working electrode in the application of photoelectrochemical solar cell (PESC).

This study aimed to further tune the capability of active metal exsolution onto the surface of the CO oxidative perovskite catalyst La 0.7 Ce 0.1 Co 0.3 Ni 0.1 Ti 0.6 O 3 by tuning the reducing parameter. Under same calcination temperature of 800°C, XRD analysis shown that the precursors with calcination duration of 6 hours (S 2 T 8 H 6 ) was able to achieve similar crystalline structure to those with calcination duration of 12 hours (S 2 T 8 H 12 ). In order for the active metal (CoNi) to be exsolved onto the perovskite surface, reducing parameter such as temperature and duration are deemed crucial to the reduction process. The exsolution of the active metals was observed when the samples were treated under reducing condition with varying temperatures of 550°C and 700°C and duration from 200 to 300 minutes. Through comparison with their EDX readings, S 2 T 8 H 6 treated under 700°C and 300 minutes (S 2 T 8 H 6 -R 7 H 5 ) achieved the highest weight percentage of surface Cobalt and Nickel of 3.83 and 2.81. It was clear that by tuning the temperature and duration of reduction, the exsolution of the active metals onto the surface of the perovskite could be improved resulting in better exposure and dispersion of active metals onto the surface of catalyst.

This study aimed to determine the optimum dose of 17α-MT hormone to improve male shrimp P. monodon sperm quality. Male tiger shrimp P. monodon originated from pond with an average weight (57.56 ± 12.79) g were transferred to hatchery and acclimated for 1 week prior treatments. Shrimps were set up in controlled tanks in 5 shrimps/tank density. Treatments were 17α-MT hormone induction in different doses, i.e. A = control (ablation); B = 200 ng/100 g of broodstock body weight (BW); C = 300 ng/100 g BW; and D = 400 ng/100 g BW. The 17-α MT hormone was given using injection method every 7 days in 3 times frequency. Research was completely randomized designed with 4 treatments and 2 replications. Observed variables were: the amount of shrimps which carried spermatophores, weight of spermatophores, quantity of spermatozoa, spermatophores histology and water quality. Data of the amount of shrimps which carried spermatophores, weight of spermatophores and the quantity of spermatozoa were analyzed using analysis of variance (ANOVA), while data of spermatophores histology and water quality were analyzed descriptively. The amount of shrimps which carried spermatophores and weight of spermatophores were not significantly different (P>0.05), but spermatozoa quantity was significantly different (P<0.05). The highest spermatozoa quantity was obtained at 300 ng/100 g BW dose in fourth gonad maturity stage. The 17α-MT in 300 ng/100 g BW was the optimum dose for P. monodon sperm quality improvement and it could be applied to replace ablation method.

Optimization works is an important method for Finite Element (FE) analysis to get better accuracy in simulation study before proceed for further analysis. In this present work, convergence study of local crack tip meshing involving radius of first row element, a/n (DELR) and number of crack tip element (NTHET) is employed on single edge crack in homogenous properties of human cortical bone. Mode I and Mode II Type -7 penetration were determined by using FE analysis and compared with the experimental results. Based on the results, a good agreement is found between numerical and experimental results. The first section in your paper

PtRu catalyst is a promising anodic catalyst for direct methanol fuel cells (DMFCs) but the slow reaction kinetics reduce the performance of DMFCs. Therefore, this study attempts to improve the performance of PtRu catalysts by adding nickel (Ni) and iron (Fe). Multiwalled carbon nanotubes (MWCNTs) are used to increase the active area of the catalyst and to improve the catalyst performance. Electrochemical analysis techniques, such as energy dispersive X-ray spectrometry (EDX), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS), are used to characterize the kinetic parameters of the hybrid catalyst. Cyclic voltammetry (CV) is used to investigate the effects of adding Fe and Ni to the catalyst on the reaction kinetics. Additionally, chronoamperometry (CA) tests were conducted to study the long-term performance of the catalyst for catalyzing the methanol oxidation reaction (MOR). The binding energies of the reactants and products are compared to determine the kinetics and potential surface energy for methanol oxidation. The FESEM analysis results indicate that well-dispersed nanoscale (2–5 nm) PtRu particles are formed on the MWCNTs. Finally, PtRuFeNi/MWCNT improves the reaction kinetics of anode catalysts for DMFCs and obtains a mass current of 31 A g−1 catalyst.

Reaction wheel is the most popular actuator for the attitude manoeuvring of a satellite system due to its compact size, reliability and able to produce precise torque. However, for redundancy purposes, the reaction wheels are assembled in a tetrahedral configuration that is able to generate torque in any direction even when one of the reaction wheel fails. The tetrahedral configured reaction wheel causes the maximum torque generation to be uneven in any direction. Hence, the quaternion rotation is completed at different rate in different direction. In order to optimize the rotation rate, an optimal control using iterative method via GPOPS toolbox. It is then compared with the traditional Eigen-axis Quaternion Feedback control. The improvement shown by the optimal control to be between 3.49% to 25.11% improvement in manoeuvre time depending on the direction of manoeuvre. The optimal control is able to outperform the traditional control method.

Internal fixation is a mechanism purposed to maintain and protect the reduction of a fracture. Understanding of the fixation stability is necessary to determine parameters influence the mechanical stability and the risk of implant failure. A static structural analysis on a bone fracture fixation was developed to simulate and analyse the biomechanics of a diaphysis shaft fracture with a compression plate and conventional screws. This study aims to determine a critical area of the implant to be fractured based on different implant material and angle of fracture (i.e. 0°, 30° and 45°). Several factors were shown to influence stability to implant after surgical. The stainless steel, (S. S) and Titanium, (Ti) screws experienced the highest stress at 30° fracture angle. The fracture angle had a most significant effect on the conventional screw as compared to the compression plate. The stress was significantly higher in S.S material as compared to Ti material, with concentrated on the 4th screw for all range of fracture angle. It was also noted that the screws closest to the intense concentration stress areas on the compression plate experienced increasing amounts of stress. The highest was observed at the screw thread-head junction.

Bare biomedical grade titanium alloys are prone to degradation when in a body fluid environment. Surface coatings such as Physical Vapor Deposition (PVD) can serve as one of the options to minimize this issue. Past reports showed that the PVD coated layer consists of pores, pinholes, and columnar growths which act as channels through which the aggressive medium attacks the substrate. Duplex and multilayer coatings seem able to address this issue to varying extents but at the expense of manufacturing time and cost. In this paper, the effect of an ultrasonic vibration frequency on PVD TiN coated Ti–13Zr–13Nb biomedical alloy was studied. Disk type samples were prepared and coated with TiN at fixed conditions: bias voltage (−125 V), substrate temperature (300 °C), and nitrogen gas flow rate (300 standard cubic centimeters per minute (SCCM)). An ultrasonic vibration was then subsequently applied to the TiN coated samples at frequencies of 8 kHz and 16 kHz for 5 min. All TiN coated samples treated with ultrasonic vibrations exhibited a higher corrosion resistance than the untreated ones. Microstructure analysis under Field Emission Scanning Electron Microscopy (FESEM) confirmed that the coated sample at frequencies of 16 kHz produced the most compact coating. It is believed that the hammering effect of the ultrasonic vibration reduced the micro channels’ size in the coating and thus decelerated the corrosion’s attack.