A bone regeneration strategy via dual delivery of demineralized bone matrix powder and hypoxia-pretreated bone marrow stromal cells using an injectable self-healing hydrogel

Dual delivery of demineralized bone matrix (DBM) powder and hypoxia-pretreated bone marrow stromal cells (BMSCs) using an injectable self-healing hydrogel enhances bone regeneration.

Decellularized Porcine Epiphyseal Plate-Derived Extracellular Matrix Powder: Synthesis and Characterization

The aim of this study was to develop a porcine epiphyseal plate-derived extracellular matrix powder (PEPEP) for epiphyseal plate regeneration. PEPEP was characterized by chemical assay to determine the contents of DNA and epiphyseal plate complex chemical components (glycosaminoglycan and hydroxyproline). The effects of PEPEP on the viability, proliferation, and differentiation of human bone marrow mesenchymal stem cells (hBMSCs) were also evaluated. hBMSCs cultured in PEPEP exhibited a good distribution with excellent viability after 72 h, demonstrating the ability of PEPEP to support hBMSC proliferation. At week 4 and 6 in vitro, the PEPEP + hBMSCs structure showed chondrogenic ability and an increase in expression of collagen type I, type II, and type X. PEPEP showed a promising ability to enhance cartilage formation and promote chondrocyte differentiation, maturation, and hypertrophy. The results provide insights into the feasibility of PEPEP as a potential material for tissue engineering applications.

The Effect of Thickness on the Properties of Laser-Deposited NiBSi-WC Coating on a Cu-Cr-Zr Substrate

Ni/60WC coatings on copper substrate were placed via laser deposition (LD). A structural study was conducted using electron microscopy and a microhardness evaluation. Two body abrasive wear tests were conducted with a pin-on-plate reciprocating technique. A tool steel X12MF GOST 5960 (C-Cr-Mo-V 1.6-12-0.5-0.2) with a hardness of 63 HRC was used as a counterpart. The following results were obtained: Precipitation of the secondary carbides takes place in the thicker layers. Their hardness is lower than that of the primary carbides in the deposition (2425 HV vs. 2757 HV) because they mix with the matrix material. In the thin layers, precipitation is restricted due to a higher cooling rate. For both LD coatings, the carbide’s hardness increases compared to the initial mono-tungsten carbide (WC)-containing powder (2756 HV vs. 2200 HV). Such a high level of microhardness reflects the combined influence of a low level of thermal destruction of carbides during laser deposition and the formation of a boride-strengthening phase from the matrix powder. The thicker layer showed a higher wear resistance; weight loss was 20% lower. The changes in the thickness of the laser deposited Ni-WC coating altered its structure and wear resistance.

Production and Processing of a Spherical Polybutylene Terephthalate Powder for Laser Sintering

This work describes the production of a spherical polybutylene terephthalate (PBT) powder and its processing with selective laser sintering (SLS). The powder was produced via melt emulsification, a continuous extrusion-based process. PBT was melt blended with polyethylene glycol (PEG), creating an emulsion of spherical PBT droplets in a PEG matrix. Powder could be extracted after dissolving the PEG matrix phase in water. The extrusion settings were adjusted to optimize the size and yield of PBT particles. After classification, 79 vol. % of particles fell within a range of 10–100 µm. Owing to its spherical shape, the powder exhibited excellent flowability and packing properties. After powder production, the width of the thermal processing (sintering) window was reduced by 7.6 °C. Processing of the powder on a laser sintering machine was only possible with difficulties. The parts exhibited mechanical properties inferior to injection-molded specimens. The main reason lied in the PBT being prone to thermal degradation and hydrolysis during the powder production process. Melt emulsification in general is a process well suited to produce a large variety of SLS powders with exceptional flowability.

Processing of Porous Stainless Steel by Compaction Method Using Egg Shell as Space Holder

Development of lightweight materials becomes essential and has been applied for various structural and functional applications in industrial field since last decade. Porous metal can contribute to lightweight material with great mechanical, thermal and electrical properties. In this study, porous stainless steel was fabricated by using powder metallurgy technique and egg shell as a new potential space holder material. Stainless steel 316L was used as metal matrix powder, egg shells as space holder material, and polyethylene glycol (PEG) as binder to increase the green density of the preforms. The material was mixed using roller mill before the mixtures are ready to the next process of compaction by using uniaxial pressing machine. The samples were sintered to two-stage sintering at temperature 1000°C in a tube furnace. Physical properties of porous stainless steel were studies by performing density and porosity test. Scanning Electron Microscopy (SEM) apparatus was used to characterize morphology properties. The results show that, porous stainless steel with the composition of 30 wt. % of egg shells added into formulation yields the highest porosity compared to other compositions and the distribution of pores can be classify as micro-pores.

Effect of matrix powder and reinforcement content on tribological behavior of particulate 6061Al-TiB2 composites

In the present work, 6061Al-TiB2 composites were synthesized using two types of base 6061Al powder (prealloyed and premixed) through powder metallurgy route. Dry sliding wear test was performed on the specimens using pin on disk apparatus to investigate the effect of TiB2 content on tribological characteristics. The microstructure, worn surface, and subsurface were also characterized using scanning electron microscope to examine the wear mechanism of prealloyed- and premixed-based composites. A mathematical model was developed using parameters (composition and applied load) to predict wear rate and correlated with experimental results. Adequacy of developed model has been validated using analysis of variance. Results indicated that premixed 6061Al-TiB2 composites have superior tribological properties as compared to the prealloyed 6061Al-TiB2 composite.