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Nowadays, there has been continuous development of metallic biomaterials to meet special needs in the manufacturing of biomedical implants, units and systems so as to function well in the required environment. Developed biomaterials which possess exceptional properties in terms of biocompatibility and biomechanical compatibility require precision processing and machining to obtain the desired dimensional tolerances. Electrical discharge machining (EDM) is the noncontact or nontraditional process of machining that suits the precision machining of biomaterials. In this work, an effort was made to optimize the EDM parameters during machining of titanium-based biomaterials Ti-6AL-4V, so that the multi-objective responses could be obtained. The response surface method was used in designing the experiment, while the grey relational method was used to analyze the effect of multiple objectives into a single unit. The electrical parameters that were considered in this study include peak current, gap voltage, pulse turn-on and duty cycle. These parameters were set within the acceptable limits of the equipment. Three responses were studied, which are tool wear rates (TWRs), material removal rate (MRR) and surface roughness (SR). Using the signal-to-noise ratio and ANOVA optimum tool/electrode wear rate (TWR) is obtained at $5\times 10^{-5}$g/min with process parameters $\mathrm{\text{Ip}}=6$ A, $\mathrm{\text{Vg}}=30$V, $\mathrm{\text{Ton}}=200$$\mu$s, $D=65$%. Optimum values of material removal rate (MRR) are obtained as 0.01035g/min with process parameters $\mathrm{\text{Ip}}=6$ A, $\mathrm{\text{Vg}}=60$V, $\mathrm{\text{Ton}}=140$$\mu$s, $D=50$%. Optimum SR is observed as 2.258$\mu$m with EDM process parameters $\mathrm{\text{Ip}}=6$ A, $\mathrm{\text{Vg}}=90$V, $\mathrm{\text{Ton}}=200$$\mu$s, $D=65$%. Surface characteristics are verified with SEM micrographs. Whereas, grey relation analysis predicted the multi-objective optimum response characteristics. Based on the grey relation grade, experiment number 7 ($\mathrm{\text{Ip}}=6$A, $\mathrm{\text{Vg}}=90$V, $\mathrm{\text{Ton}}=200$$\mu$s, $D=65$%) secured the first rank among the experiments/trails.

In order to improve the corrosion resistance of Ni-Ti alloys, mechanically polished Ni-Ti alloys discs were subjected to isothermal oxidation (TO) treatment in N₂-20vol.%O₂ at temperatures ranging from 300 to 800°C. TO-treated surfaces were then analyzed by Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive X-ray spectroscopy (EDX), and X-ray electron spectroscopy (XPS). Electrochemical corrosion tests and wear tests were carried out. Ni-Ti alloys exhibited different oxidation behavior depending on the treatment temperatures. An almost Ni free layer was observed on the surface layer of the specimens treated at temperatures 500°C and above. TO-treated specimens showed a higher corrosion resistance compared to that of the untreated sample, and a higher wear resistance. Consequently, TO-treatment produced an almost nickel free smooth protective oxide layer, which might contribute to good biocompatibility.

Nanocrystalline biphasic calcium phosphate (BCP) powder was synthesized from natural bovine bone via a very economic process. The bovine bone was annealed at 900°C for 2 h and elemental compositions were qualitatively identified by energy dispersive X-ray spectroscopy (EDS) in the scanning electron microscope (SEM). The calcined bovine bone was powdered and mixed with calcium hydrogen phosphate dihydrate (CaHPO₄·2H₂O, DCPD). After that, the prepared powder was uniaxially pressed into pellets. The pellets were annealed at 900–1200°C and then crushed to obtain nanocrystalline BCP powder. The morphology and microstructure of the BCP powder were studied by SEM. The results showed that the prepared powder consisted of small size and highly agglomerated particles. X-ray diffraction method was utilized to characterize the phase formation and crystallite size of prepared powder. The crystallite sizes of BCP powder calculated by using XRD data were in the range of 20–60 nm.

The effect of hydrothermal crystallization and adding reinforced intermediate layers on improving the tensile adhesion of plasma-sprayed HA coatings (HAC) was investigated. The experimental results show that the index of crystallinity (IOC) and phase purity of hydrothermally-treated HAC (HT-HAC) are increased by the low-temperature hydrothermal treatment. The microstructural healing effect with nano-size HA crystallites is significant to diminish the defects and prevent mechanical strength degradation for the HT-HAC. XPS analysis demonstrates that hydrothermal crystallization helps to promote the interfacial Ti–OH chemical reaction. HA composite coatings with CP-Ti and ZrO₂ intermediate layers provide another strengthening effect compared with the hydrothermal-heating method. The inter-diffusion of Ca results in a chemical bonding at the HA/ZrO₂ interface, which results in the increase of the adhesive strength of composite coatings. The fracture behavior is different between the crystallization-induced HAC and the composite coatings. The HT-HAC remains on the substrate with an evident cohesive failure. The adhesive failure occurred at HA/intermediate layers for composite coatings. Failures with less percentage area of interfacial fracture are indicative of a higher strength of a coating.

A study on the acoustic emission (AE) characteristics during deformation of nacre material was performed. We found that intermittent AE events are generated during nacre deformation. These avalanches may be attributed to microfracture events of the aragonite (CaCO₃) nano-asperities and bridges during tablet sliding. These events show several critical features, such as the power-law distributions of the avalanche sizes and interval. These results suggest that the underlying fracture dynamics during nacre deformation display a self-organized criticality (SOC). The results also imply that the disorder and long-range correlation between local microfracture events may play important roles in nacre deformation.

In the present study, two novel silicate glass-ceramics having chemical composition 38SiO₂–41CaO–6P₂O₅–($15-x$)Na₂O–$x$CaF₂ ($x=0$, 0.43 mol%) were synthesized. These glass derivatives were subjected to stimulated body fluid for 24 days in SBF under static condition at $37^{\circ }$C in order to evaluate the bioactive properties of specimens. The antibacterial activity of glass ceramics against three pathogenic bacteria was determined using the modified Kirby Bauer method. It was found that the antibacterial activity primarily depends on the dissolution rate; faster release of ions caused rapid increase in the pH of the solution. Antibacterial properties were found to be strongly affected by changes in the pH of supernatant. The in vitro bioactivity assays showed that both glass derivatives were capable of bonding with bone and secondly effectively inhibit bacteria. However, the glass ceramic without CaF₂ (B2) showed high dissolution rate, better bioactive ability and stronger antibacterial efficacy.

Calcium phosphate based biomaterials play important roles in clinical applications. Calcium pyrophosphate (CPP), a kind of calcium phosphate, can be used as a bone substitution material as well as a bone graft. Because of its similarity to inorganic component of bone and teeth it can be used for surface coating of metallic dental and orthopedic implants. In the present study, calcium pyrophosphate dihydrate (CPPD) nanoparticles were synthesized using surfactant mediated approach. Crystalline nature and average crystallite size was studied using Powder XRD. The CPPD nanocrystallites were found to be triclinic from powder XRD. The TEM study indicated that CPPD nanoparticles were in the range of 13 nm to 20 nm. The presence of various bonds was confirmed by FTIR spectroscopy. The amount of water of hydration and the thermal stability was studied by thermogravimetry. The variations of various dielectric parameters with the frequency of applied field in 3.2 kHz to 32 MHz range and within a temperature range from 60°C to 120°C were studied. The formation of other phases such as β-CPP and α-CPP on heating of CPPD at 900°C and 1250°C, respectively, were studied by the Powder XRD. The results are discussed.

Porous Mg alloys will be promising orthopedic implants materials. In this study, porous Mg–Zn alloy with a porosity of 30% was prepared by powder metallurgy process. XRD was used to examine the composition of the sample and synchrotron radiation-based X-ray micro-computed tomography (SR-μCT) was used to investigate the pore properties of the sample. The results showed that the sample comprised a single Mg phase and a Mg₂Zn₁₁ phase. The SR-μCT results showed that the porosity of the sample is about 30% which is approximate to the theoretical porosity. The pore morphology was irregular and the largest pore was about 200 μm in diameter. And a large pore cluster was identified meaning that most of the pores in the sample were interconnected with each other. This is beneficial for the materials transformation after the implantation of the sample in human body, which will boost the bone regeneration. Drug-loading experiment showed that Ibuprofen can be successfully loaded in porous Mg–Zn alloy, which means that porous Mg–Zn alloy could be an orthopedic drug delivery system (DDS).

Aqueous silk fibroin (SF) sol is a colloidal solution. With the colloidal hydration layer and electrostatic repulsion, the SF sol can hardly make the efficient collision/assembly among micelles and perform like a following sol for a long time. In this paper, hydrophilic silk-based sequences (HSF) derived from SF molecules were obtained by immersing the dried SF condensates with water and extracting the dissolving fraction. The HSF was obtained by immersing the SF condensate dried at the temperature of $20$–$25^{\circ }\mathrm{\text{C}}$ and relative humid of 55–60% in water and collected the lixivium. The dissolving ratio was about 30%. The HSF sol (0.5%, w/v) self-assembled into the mesoscopic 3D nanofibrous network within 8 h. The obtained HSF nanofibers were 10–100 $\mu \mathrm{\text{m}}$ in length and 50–100 nm in diameter. The HSF nanofiber possesses similar hierarchical structure consisting of nanofibrils bundles to the native silk fiber. There were significant aggregation structure transitions from random coil to $\beta$-sheet and amorphous chains to Silk II crystal aggregation during the formation of HSF nanofibers. The HSF nanofiber holds the potential to give further insight into the reconstruction of native silk in vitro and the fabrication of tough silk-based biomaterials.

Cardiovascular disease is the leading cause of death worldwide and 90% of coronary interventions consists in stenting procedures. Most of the implanted stents are made of AISI 316L stainless steel (SS). Excellent mechanical properties, biocompatibility, corrosion resistance, workability and statistically demonstrated medical efficiency are the reasons for the preference of 316L SS over any other material for stent manufacture. However, patients receiving 316L SS bare stents are reported with 15–20% of restenosis probability. The decrease of the restenosis probability is the driving force for a number of strategies for surface conditioning of 316L SS stents. This review reports the latest advances in coating, passivation and the generation of controlled topographies as strategies for increasing the corrosion resistance and reducing the ion release and restenosis probability on 316L SS stents. Undoubtedly, the future of technique is related to the elimination of interfaces with abrupt change of properties, the elimination of molecules and any other phase somehow linked to the metal substrate. And leaving the physical, chemical and topographical smart modification of the outer part of the 316L SS stent for enhancing the biocompatiblization with endothelial tissues.

Surface micro/nanotopography of orthopedic implants plays a significant role in determining their biological performance. In this study, plasma jet was for the first time utilized to modulate the micro/nanostructure of the plasma-sprayed 50% Nb₂O₅-TiO₂ coating on the biomedical Ti alloy based on its high temperature and super-high cooling rate characteristics. Results show that the plasma jet can modulate the shape, dimension and distribution of the surface grains in a process-parameter-dependent manner, thus being able to tailor the micro/nanotopography of the surface coating. In vitro cell culture experiments proved that the plasma jet-induced topographical changes have great effects on the osteogenic activity of the MC3T3-E1 cells cultured on the coating surface.

In this work, TiAlV thin films have been prepared on two different types of substrates: silicon and stainless steel (SS304) by two deposition methods: Pulsed Laser Deposition (PLD) and DC magnetron sputtering. Different techniques have been employed in order to characterize film properties such as: Scanning Electron Microscopy (SEM) equipped with Energy Dispersive X-ray (EDX), X-ray diffraction (XRD), microhardness and corrosion test. EDX analysis showed that the deposited films are slightly different from that of the target material Ti6Al4V alloy. The measured microhardness values are about 11.7GPa and 4.7GPa for films prepared by PLD and DC magnetron sputtering, respectively. Corrosion test indicated that the corrosion resistance of the two TiAlV films deposited on SS304 substrates in (0.9% NaCl) physiological normal saline medium was significantly improved compared with the SS304 substrates. These attractive results could permit applications of our films in the medical implants fabrication.

An upsurge in demand and extensive effort in orthopedic implants directed toward innovative biomaterials for orthopedic applications. Orthopedic implants are significantly used in mature alternatives to retain, restore or modify the defective bone or tissue. However, exhaustive research in the past reveals various health-associated problems that can be effectively overcome by inventing newer kinds of biomaterials. The selection of optimal materials and the fabrication process are crucial challenges enforced by numerous novel materials that could be made for orthopedic applications. This paper intends to systematically assess the processing method employed in manufacturing the biomaterials for orthopedic applications. However, the success of biomedical implants in orthopedic are commonly restricted owing to insufficient bone-implant integration, wear debris induced osteolysis, and implant-associated infections. Nevertheless, the endeavor has also been intended to enhance the biological properties of the biomaterials by surface modification process while retaining their strength and hardness. Furthermore, various surface modifications have been comprehended. This review conferred contemporary advancements in surface coating approaches in orthopedic to enhance their osteointegration, improve corrosion resistance and accomplish antibacterial performance, clinical success and long-term service. The insight review has revealed the current outcomes in the field of engineering biomaterials concerning surface modifications of metallic implants or composite for enhancing their biological properties.

Titanium and its alloys used in biomaterial applications are preferrably the cause of high-corrosion resistance properties in addition to having good mechanical properties. Commercially pure Ti (CP-Ti) (Grade 2), Ti6Al4V (Grade 5) and Ti6Al4V-ELI (Grade 23) samples are used as biomaterials exposed to 750^∘C and 1060^∘C for 1h. The samples were cooled in air after heat treatment at 750^∘C, the other samples were cooled in water after heat treatment at 1060^∘C. The free-heat treatment samples are as producted. Microstructures of heat-treated samples and non-made samples by comparison were evaluated before and after corrosion process microstructures and tensile strengths. Test solution is 0.5mol H₂SO${}_4+1$mol HCl mixture. The corrosion resistance of the titanium samples was evaluated. Microstructure images were monitorized on optical and SEM microscopes.

In this paper, the effect of heat treatment was determined on the microstructure, mechanical properties and corrosion resistances of the material. As a result, heat treatment is useful on corrosion resistance of alloyed samples.

As implant materials, titanium and its alloys have been extensively utilized because of their exceptional mechanical properties and biocompatibility. Despite this, corporations and researchers alike have kept up their aggressive pursuit of better alloys since there are still issues that require immediate attention. One of these causes a problem with stress shielding as a noticeable variation in the elastic modulus of the implant material. Ti alloys release harmful ions after extended usage. The poor bioactivity of the Ti alloy surface slows the healing process. In order to address these problems, additional research has concentrated on developing Ti alloys for the 21st century that contain a more suitable phase and change the surface of the alloy from inherently bioinert to bioactive. This study assesses the knowledge presently existing on the biological, chemical, mechanical, and electrochemical characteristics of important $\beta$-Ti alloys created in recent years with the objective to provide scientific justification for using $\beta$-titanium-based alloys as a substitute for cpTi. Dental implants might be made using $\beta$-Ti alloys as an alternative. The enhanced alloy qualities, which include a lower modulus of elasticity, improved strength, suitable biocompatibility, and good abrasion and excellent resistance to corrosion, offer the essential proof. Additionally, structural, chemical, and thermomechanical modifications to $\beta$-Ti alloys allow for the production of materials that may be tailored to the needs of unique instances for clinical practises. By researching the paper, the performance and attributes of $\beta$-titanium alloy are compared to those of other forms of titanium alloy, such as $\alpha$ titanium alloys. To support their usage as cpTi substitutes, in vivo studies are required to assess new $\beta$-titanium alloys.

In order to improve the interfacial bonding at coating-substrate, a graphene oxide-hydroxyapatite (GH) coating was designed and constructed. The microstructure, bonding strength and in vitro bioactivity of the coating were analyzed. The results showed that GH coating presented uniform and crack-free structure with a flake morphology. The bonding strength of GH coating was 7.81MPa, which is about 1.2 times that of pure hydroxyapatite coating. In vitro bioactivity test using simulated body fluid exhibited that GH coating processes the ability to induce apatite formation. The GH coating should have potential application in surface modification for biomedical materials.

A wide variety of surgical procedures ranging from laminectomy to vertebral body resection are used to restore spinal function. Accordingly, a wide range of man-made and natural materials are used as supplements to improve the long term success rate of these procedures and patient comfort. Requirements for the materials used in spine surgery are similar to other applications; tissue compatibility in terms of mechanical, chemical and pharmacological requirements. The requirements may change as the tissue heals with time. It is imperative that the materials be "dynamic" in their abilities to respond to the changing environmental needs. Due to technical innovations in the area of biomaterials, newer materials have been proposed for the spinal surgery. Graft materials (fat, allo-, auto, BMP), metals, polymers, ceramics, and composites are used to restore spinal function.

The article is about the biotechnology and pharmaceutical industries in Taiwan. It touches on current status and forecast of biotechnology and pharmaceutical industries in Taiwan.

The article is about biotechnology in National Cheng Kung University.

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