Nanoscale Generators for Tissue Healing: A Perspective.

Electroactive components can promote tissue healing and control neuronal activity with the support of the tissue environment and offer electrical impulses and biocompatible material habitats. Due to the increasing growth of portable electronics, it is imperative to generate tiny, lightweight power supply appliances with outstanding performance and sustainable energy conversion ability. In order to deal with the energy deficiency of electronic devices, self-powered systems based nanogenerators are committed to capturing ambient energy for electronic device consumption.

On the Ion Implantation Synthesis of Ag-Embedded Over Sr-Substituted Hydroxyapatite on a Nano-Topography Patterned Ti for Application in Acetabular Fracture Sites.

Introduction: There is an ongoing need for improved healing response and expedited osseointegration on the Ti implants in acetabular fracture sites. To achieve adequate bonding and mechanical stability between the implant surface and the acetabular fracture, a new coating technology must be developed to promote bone integration and prevent bacterial growth.

Methods: A cylindrical Ti substrate mounted on a rotating specimen holder was used to implant Ca, P, and Sr ions at energies of 100 KeV, 75 KeV and 180 KeV, respectively, using a low-energy accelerator to synthesize strontium-substituted hydroxyapatite at varying conditions.

Exploring fibroblast interactions on nanocrystalline surfaces in physiological environments through a phenomenological lens.

The cytological behaviour and functional dynamics (adhesion, spreading, synthesis of proteins) of fibroblasts when interacting with biomedical surfaces are intricately influenced by the inherent nature of surface (nanocrystalline or microcrystalline), where the nanocrystalline (NC) surface is preferred in relation to the microcrystalline (MC) surface. This preference is a direct consequence of the distinct differences in physical and chemical characteristics between NC and MC surfaces, which include crystal boundary bio-physical attributes, electron work function, surface energy, and charge carrier density. The observed variances in cytological behaviour at the interfaces of NC and MC bio-surfaces can be attributed to these fundamental differences, particularly accounting for the percentage and nature of crystal boundaries.

Process-structure-biofunctional paradigm in cellular structured implants: an overview and perspective on the synergy between additive manufacturing, bio-mechanical behaviour and biological functions.

The overview describes the synergy between biological sciences and cellular structures processed by additive manufacturing to elucidate the significance of cellular structured implants in eliminating stress shielding and in meeting the bio-mechanical property requirements of elastic modulus, impact resistance, and fatigue strength in conjunction with the biological functionality. The convergence of additive manufacturing, computer-aided design, and structure-property relationships is envisaged to provide the solution to the current day challenges in the biomedical arena. The traditional methods of fabrication of biomedical devices including casting and mechanical forming have limitations because of the mismatch in micro/microstructure, mechanical, and physical properties with the host site.

The significance of thermomechanical processing on the cellular response of biomedical Co-Cr-Mo alloys.

Strengthening of biomedical Co-Cr-Mo alloys has been explored via thermomechanical processing for enhancing the durability of their biomedical applications. However, the effects of cold and hot deformation on the cellular activity continue to be unclear. In this study, we prepared Co-Cr-Mo alloy rods via cold swaging and hot-caliber rolling and studied the relationship between the microstructure and cellular response of pre-osteoblasts.

Improving Biological Functions of Three-Dimensional Printed Ti2448 Scaffolds by Decoration with Polydopamine and Extracellular Matrices.

Extracellular matrices (ECMs) provide important cues for cell proliferation and differentiation in the complex environment, which show a significant influence on cell functions. Herein, cell-derived ECMs were deposited on the polydopamine (PDA)-decorated porous Ti-24Nb-4Zr-8Sn (Ti2448) scaffolds fabricated by the electron beam melting method in order to improve biological functions. The influence of PDA-ECM coatings on cell functions was further investigated.

Effects of integrated bioceramic and uniaxial drawing on mechanically-enhanced fibrogenesis for bionic periosteum engineering.

Periosteum is clinically required for the management of large bone defects. Attempts to exploit the periosteum's participation in bone healing, however, have rarely featured biological and mechanical complexity for the scaffolds relevant to translational medicine. In this regard, we report engineering of bioinspired periosteum with co-delivery of ionic and geometry cues.

Recent Advances on Development of Hydroxyapatite Coating on Biodegradable Magnesium Alloys: A Review.

The wide application of magnesium alloys as biodegradable implant materials is limited because of their fast degradation rate. Hydroxyapatite (HA) coating can reduce the degradation rate of Mg alloys and improve the biological activity of Mg alloys, and has the ability of bone induction and bone conduction. The preparation of HA coating on the surface of degradable Mg alloys can improve the existing problems, to a certain extent.

The significance of phase reversion-induced nanograined/ultrafine-grained (NG/UFG) structure on the strain hardening behavior and deformation mechanism in copper-bearing antimicrobial austenitic stainless steel.

The unique concept of phase reversion involving severe deformation of parent austenite into martensite, followed by annealing for a short duration, whereby the strain-induced martensite reverts to austenite, was adopted to obtain nano-grained/ultrafine-grained (NG/UFG) structure in a Cu-bearing biomedical austenitic stainless steel resulting in high strength-high ductility combination. Work hardening and accompanying deformation mechanism are two important aspects that govern the mechanical behavior of biomedical devices. Thus, post-mortem electron microscopy of the strained region was carried out to explore the differences in the deformation mechanisms induced by grain refinement, while the strain hardening behavior was analyzed by Crussard-Jaoul (C-J) analysis of the tensile stress-strain data.

The synergistic effect of grain boundary and grain orientation on micro-mechanical properties of austenitic stainless steel.

Micro/nano-scale deformation behavior including hardness, elastic modulus, and pop-ins, was studied in a medical austenitic stainless steel followed by post-mortem EBSD characterization. Relatively higher hardness and modulus was observed near {101} and more pop-ins occurred in this orientation at high loading rate. The activation volume (v) obtained from nanoindentation had weak dependence on grain orientation and was ~10-20 b, indicating that neither diffusional creep processes nor conventional dislocation segments passing through dislocation forests controls plastic deformation in our study.

Evolution of the Shear Band in Cold-Rolling of Strip-Cast Fe-1.3% Si Non-Oriented Silicon Steel.

Cube texture and microstructural evolution of as-cast non-oriented silicon steel (1.3% Si) during cold rolling and annealing were studied. The results showed that the as-cast microstructure with grain size in the range of 100-500 μm had a weak texture.

The effect of different coatings on bone response and degradation behavior of porous magnesium-strontium devices in segmental defect regeneration.

Regeneration of long-bone segmental defects remains a challenge for orthopedic surgery. Current treatment options often require several revision procedures to maintain acceptable alignment and achieve osseous healing. A novel hollow tubular system utilizing magnesium-strontium (Mg-Sr) alloy with autogenous morselized bone filled inside to repair segmental defects was developed.

The Significance of Coherent Transformation on Grain Refinement and Consequent Enhancement in Toughness.

Coherent transformation is considered to be an effective approach to refine the microstructure and enhance toughness of structural steels. However, there are gaps in the knowledge on the key aspects of microstructure that govern toughness. In this regard, a low alloyed experimental steel with lean chemistry was subjected to a simple heat treatment involving austenitization at different temperatures, followed by quenching and tempering to obtain bainitic microstructures with different boundary composition.

The Impact of Interphase Precipitation on the Mechanical Behavior of Fire-Resistant Steels at an Elevated Temperature.

In this study, we address the challenge of obtaining high strength at ambient and elevated temperatures in fire-resistant Ti-Mo-V steel with ferrite microstructures through thermo-mechanical controlled processing (TMCP). Thermally stable interphase precipitation of (Ti, Mo, V)C was an important criterion for retaining strength at elevated temperatures. Electron microscopy indicated that interphase precipitation occurred during continuous cooling after controlled rolling, where the volume fraction of interphase precipitation was controlled by the laminar cooling temperature.

The significant impact of mechanically-induced phase transformation on cellular functionality of biomedical austenitic stainless steel.

The implant surface and tissue experience strain when micro-motion occurs at the bone-implant interface under physiological loading. Moreover, strain is also introduced on the surface during mechanical processing of biomedical devices. Both these situations can induce phase transformation depending on the degree of stability of the microstructural constituents.

The significance of phase reversion-induced nanograined/ultrafine-grained structure on the load-controlled deformation response and related mechanism in copper-bearing austenitic stainless steel.

The ingenious concept of phase reversion annealing involving cold deformation of parent austenite to strain-induced martensite, followed by annealing was used to obtain nano-grained/ultrafine-grained (NG/UFG) structure in a Cu-bearing biomedical austenitic stainless steel resulting in high strength-high ductility combination. Having employed the concept effectively, the primary objective of this study is to critically analyze the interplay between the load-controlled deformation response, strain-rate sensitivity and deformation mechanism of NG/UFG austenitic stainless steel via nanoscale deformation experiments and compare with its coarse-grained (CG) counterpart. The study demonstrated that the strain-rate sensitivity of NG/UFG was ~1.

Mechanistic understanding of compression-compression fatigue behavior of functionally graded Ti-6Al-4V mesh structure fabricated by electron beam melting.

In recent years, mesh structures have attracted significant interest for structural and functional applications. However, the mechanical strength and energy absorption ability of uniform mesh structured materials degrade with density. To address this challenge, we propose the concept of functionally graded mesh structures.

In-situ monitoring of the electrochemical behavior of cellular structured biomedical Ti-6Al-4V alloy fabricated by electron beam melting in simulated physiological fluid.

Ti-6Al-4V alloys with cellular structure fabricated by additive manufacturing are currently of significant interest because their modulus is comparable to bone and the cellular structure allows the cells to penetrate and exchange nutrients, promoting osseointegration. We describe here a unique simulation device that replaces the traditional steady electrochemistry approach, enabling in-situ study of variation of ion concentration and surface potential with pore depth for cellular structured Ti-6Al-4V alloys fabricated by electron beam melting (EBM) in phosphate buffered saline (PBS). This approach addresses the scientific gap on the electrochemical behavior of cellular structured titanium alloys.

Favorable modulation of osteoblast cellular activity on Zr-modified Co-Cr-Mo alloy: The significant impact of zirconium on cell-substrate interactions.

Cobalt-chromium-molybdenum alloys exhibit good mechanical properties (yield strength: ~530 MPa, ultimate tensile strength: ~1114 MPa, elongation-to-failure: ~47.3%, and modulus: ~227 GPa) and corrosion resistance. In recent years, from the perspective of osseointegration, they are considered to be lower in rank in comparison to the widely used titanium alloys.

The Significant Impact of Carbon Nanotubes on the Electrochemical Reactivity of Mg-Bearing Metallic Glasses with High Compressive Strength.

Here, we elucidate the significant impact of carbon nanotubes (CNTs) on the electrochemical behavior of Mg-based amorphous composite materials that were reinforced with CNTs while using pressure die casting. The addition of 3 vol % CNTs led to an increase in the compressive strength of Mg-based amorphous material from 812 MPa to 1007 MPa, and the fracture strain from 1.91% to 2.

On the mechanical behavior of austenitic stainless steel with nano/ultrafine grains and comparison with micrometer austenitic grains counterpart and their biological functions.

Conventional coarse-grained (CG) biomedical austenitic stainless steel with grain size in the micrometer range was subjected to a novel phase reversion concept involving severe cold deformation, followed by annealing, when the cold deformed martensite reverts to austenite with grain size in the nanometer/ultrafine (NG/UFG) regime (~200-400 nm). The mechanical behavior of CG and NG/UFG steels was studied via load-controlled and displacement-controlled experiments using a nanoindentation technique with the aim to simulate micromotion. The plastic zone associated with the indentation-induced deformed region was characterized by post-mortem electron microscopy of the deformed region to elucidate the deformation mechanism.

The Impact of Process Parameters on Microstructure and Mechanical Properties of Stainless Steel/Carbon Steel Clad Rebar.

In this study, a 304/20MnSi stainless-steel clad rebar was prepared by single-pass compression process using the MMS-200 Thermal Mechanical Simulator. The impact of different degrees of deformation and deformation temperature on microstructure evolution and the mechanical properties of stainless steel clad rebars were investigated. The study indicated that with the increase of the degree of deformation, the content of pearlite in a carbon steel matrix was increased, and the grains refined.

Influence of Inter-Pass Cooling on Microstructural Evolution and Plastic Deformation of Heavy EH47 Plates.

Herein, the influence of inter-pass cooling (IC) and conventional two-stage rolling (CTR), on microstructural evolution and plastic deformation behavior of ultra-heavy EH47 plates, is demonstrated. It is reported that the deformation amount and deformation rate, in every deformation pass during rough rolling, at 1/4- and 1/2-thickness of IC steel were higher than the CTR steel. The volume fraction of ferrite and acicular ferrite was 45% and 18%, at 1/4-thickness, and 35% and 50% at 1/2-thickness of IC steel, respectively, whereas the sum of both ferrite phases was smaller than 25% in the CTR steel.