Optical Centers in Cr-, Mn-, and O-Doped AlN and Their Thermodynamic Stability Designed by a Multiscale Computational Approach.

The optical centers in AlN can frequently exist in various charge states and can be accompanied by many coexisting defect species, creating a complex environment where mutual interactions are inevitable. Therefore, it is an immediate quest to design AlN crystal growth protocols that can target a specific optical center of interest and tune its concentration while preventing the formation of other unwanted point defects. Here, we provide a powerful workflow for point defect engineering in wide band gap, binary semiconductors that can be readily used to design optimal crystal growth protocols through combining CALPHAD-based phase analysis, and defect calculations.

Atomistic Origins of Various Luminescent Centers and n-Type Conductivity in GaN: Exploring the Point Defects Induced by Cr, Mn, and O through an Thermodynamic Approach.

GaN is a technologically indispensable material for various optoelectronic properties, mainly due to the dopant-induced or native atomic-scale point defects that can create single photon emitters, a range of luminescence bands, and n- or p-type conductivities. Among the various dopants, chromium and manganese-induced defects have been of particular interest over the past few years, because some of them contribute to our present-day light-emitting diode (LED) and spintronic technologies. However, the nature of such atomistic centers in Cr and Mn-doped GaN is yet to be understood.

Surface analysis of (Ti,Mg)N coated bone fixation devices following the rabbit femur surgery.

Background: Magnesium (Mg) enhances the bone regeneration, mineralization and attachment at the tissue/biomaterial interface.

Objective: In this study, the effect of Mg on mineralization/osseointegration was determined using (Ti,Mg)N thin film coated Ti6Al4V based plates and screws in vivo.

Methods: TiN and (Ti,Mg)N coated Ti6Al4V plates and screws were prepared using arc-PVD technique and used to fix rabbit femur fractures for 6 weeks.

Biocompatibility and Mechanical Stability of Nanopatterned Titanium Films on Stainless Steel Vascular Stents.

Nanoporous ceramic coatings such as titania are promoted to produce drug-free cardiovascular stents with a low risk of in-stent restenosis () because of their selectivity towards vascular cell proliferation. The brittle coatings applied on stents are prone to cracking because they are subjected to plastic deformation during implantation. This study aims to overcome this problem by using a unique process without refraining from biocompatibility.

Effect of TaO content on the osseointegration and cytotoxicity behaviors in hydroxyapatite-TaO coatings applied by EPD on superelastic NiTi alloys.

In the present study, the different contents of tantalum pentoxide (TaO: 10, 15, 20 and 30 wt%) nanoparticles were introduced into the natural hydroxyapatite (nHA) coating structure on NiTi substrate through electrophoretic deposition (EPD) method. The phase compositions of coatings were perused before and after the sintering at 800 °C for 1 h by XRD. The incorporation of 30wt%TaO into nHA matrix induced the formation of undesirable soluble Ca(PO) phase in composite coating.

Self-assembling antimicrobial peptides on nanotubular titanium surfaces coated with calcium phosphate for local therapy.

Bacterial infection is a serious medical problem leading to implant failure. The current antibiotic based therapies rise concerns due to bacterial resistance. The family of antimicrobial peptides (AMP) is one of the promising candidates as local therapy agents due to their broad-spectrum activity.

Magnesium doping on TiN coatings affects mesenchymal stem cell differentiation and proliferation positively in a dose-dependent manner.

Background: In vitro evaluation of cell-surface interactions for hard tissue implants have mostly been done using osteoblasts. However, when an implant is placed in the body, mesenchymal stem cells (MSCs) play a major role in new bone formation. Therefore, using MSCs in cell-surface investigations may provide more reliable information on the prediction of in vivo behavior of implants.

Photocatalytical Antibacterial Activity of Mixed-Phase TiO2 Nanocomposite Thin Films against Aggregatibacter actinomycetemcomitans.

Mixed-phase TiO2 nanocomposite thin films consisting of anatase and rutile prepared on commercially pure Ti sheets via the electrochemical anodization and annealing treatments were investigated in terms of their photocatalytic activity for antibacterial use around dental implants. The resulting films were characterized by scanning electron microscopy (SEM), and X-ray diffraction (XRD). The topology was assessed by White Light Optical Profiling (WLOP) in the Vertical Scanning Interferometer (VSI) mode.

Behavior of mammalian cells on magnesium substituted bare and hydroxyapatite deposited (Ti,Mg)N coatings.

TiN and (Ti,Mg)N thin film coatings were deposited on titanium substrates by using cathodic arc physical vapor deposition (arc-PVD) technique with magnesium contents of 0, 4.24 at% (low Mg) and 10.42 at% (high Mg).

Antibacterial Activity of As-Annealed TiO2 Nanotubes Doped with Ag Nanoparticles against Periodontal Pathogens.

It is important to develop functional transmucosal implant surfaces that reduce the number of initially adhering bacteria and they need to be modified to improve the anti-bacterial performance. Commercially pure Ti sheets were anodized in an electrolyte containing ethylene glycol, distilled water and ammonium fluoride at room temperature to produce TiO2 nanotubes. These structures were then annealed at 450°C to transform them to anatase.

Magnesium substituted hydroxyapatite formation on (Ti,Mg)N coatings produced by cathodic arc PVD technique.

In this study, formation of magnesium substituted hydroxyapatite (Ca10-xMgx(PO4)6(OH)2) on (Ti,Mg)N and TiN coating surfaces were investigated. The (Ti1-x,Mgx)N (x=0.064) coatings were deposited on titanium substrates by using cathodic arc physical vapor deposition technique.

Addressable self-immobilization of lactate dehydrogenase across multiple length scales.

Successful nanobiotechnology implementation largely depends on control over the interfaces between inorganic materials and biological molecules. Controlling the orientations of biomolecules and their spatial arrangements on the surface may transform many technologies including sensors, to energy. Here, we demonstrate the self-organization of L-lactate dehydrogenase (LDH), which exhibits enhanced enzymatic activity and stability on a variety of gold surfaces ranging from nanoparticles to electrodes, by incorporating a gold-binding peptide tag (AuBP2) as the fusion partner for Bacillus stearothermophilus LDH (bsLDH).

Effect of solid surface charge on the binding behaviour of a metal-binding peptide.

Over the last decade, solid-binding peptides have been increasingly used as molecular building blocks coupling bio- and nanotechnology. Despite considerable research being invested in this field, the effects of many surface-related parameters that define the binding of peptide to solids are still unknown. In the quest to control biological molecules at solid interfaces and, thereby, tailoring the binding characteristics of the peptides, the use of surface charge of the solid surface may probably play an important role, which then can be used as a potential tuning parameter of peptide adsorption.

Bioassay-guided isolation of antibacterial and cytotoxic compounds from the mesophilic Actinomycete M-33-5.

One hundred and twenty-six mesophilic Actinomycete cultures were isolated from the Aegean region of Turkey. The antimicrobial activities of pure isolates were tested using the agar-plaque method. Based on high antimicrobial activity against methicillin resistant Staphylococcus aureus (MRSA) and Escherichia coli O157-H7 (E.