The possibilities for surface hardening of titanium alloys by alloying with nitrogen are reviewed. Alloying has been carried out in the solid state by plasma nitriding and in the liquid state by laser melting in nitrogen. Microstructure, hardness profiles, and fatigue and wear properties have been examined. Wear resistance was found to be greatly improved by both techniques, although at the expense of a drop in fatigue properties. Case depths of 0.1 mm were produced by plasma nitriding, while 0.5 mm case depths and a maximum hardness of 1400 HV0.1 were achieved by laser alloying.

A series of thermal oxidising treatments has been carried out on V alloy at temperatures ranging from 600 to 850°C to develop a new surface engineering technique for Ti-6Al-4 V and other titanium alloys. Systematic characterisation of the thermal oxidation treated surface layers was performed using GDS, XRD, SEM, and nanoindentation testing. Ball on disc friction tests show that the coefficient offriction of a Ti-6Al-4 V disc against an alumina ball was significantly reduced after oxidation treatment. The rolling-sliding wear resistance of Timetal 6-4 material against hardened 709 M 40 steel under lubricated conditions has been

BackgroundAnimal-free recombinant proteins provide a safe and effective alternative to tissue or serum-derived products for both therapeutic and biomanufacturing applications. While recombinant insulin and albumin already exist to replace their human counterparts in cell culture media, until recently there has been no equivalent for serum transferrin.ResultsThe first microbial system for the high-level secretion of a recombinant transferrin (rTf) has been developed from Saccharomyces cerevisiae strains originally engineered for the commercial production of recombinant human albumin (Novozymes' Recombumin® USP-NF) and albumin fusion proteins (Novozymes' albufuse®). A full-length non-N-linked glycosylated rTf was secreted at levels around ten-fold higher than from commonly used laboratory strains. Modification of the yeast 2 μm-based expression vector to allow overexpression of the ER chaperone, protein disulphide isomerase, further increased the secretion of rTf approximately twelve-fold in high cell density fermentation. The rTf produced was functionally equivalent to plasma-derived transferrin.ConclusionsA Saccharomyces cerevisiae expression system has enabled the cGMP manufacture of an animal-free rTf for industrial cell culture application without the risk of prion and viral contamination, and provides a high-quality platform for the development of transferrin-based therapeutics.

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BackgroundSuccessful delivery of cell-based therapeutics into patients is compromised by their short shelf-life upon release from production facilities due to the living nature of the active component that rapidly loses viability, and therefore its properties. In this context, the use of appropriate additives may contribute to the stabilisation of the cellular component within specifications for a longer time until administration.ResultsIn the present study, we evaluated the effect of different formulations on the stability of viability, identity, and potency of clinical grade multipotent mesenchymal stromal cells in suspension, both electrolyte solution and protein content were found to impact on their shelf-life. Particularly cryopreservation of cells in a Plasmalyte 148 supplemented with 2% (w/v) AlbIX (a yeast-derived recombinant albumin) and 10% (v/v) dimethyl sulfoxide, and final formulation post-thawing in Plasmalyte 148 supplemented with 2% (w/v) AlbIX enabling prolonged stability from 24 h up to 72 h in optimal conditions. Further investigation on the mechanisms of action involved revealed a delay of apoptosis progression into late stage when AlbIX was present.ConclusionsThe use of optimal formulations for each cell type of interest is crucial to extend the shelf life of cell-based pharmaceuticals and contribute to solve logistical challenges. We demonstrated that the use of Plasmalyte 148 supplemented with 2% (w/v) AlbIX resulted in superior stability of multipotent mesenchymal stromal cells without affecting their identity and multipotency.Electronic supplementary materialThe online version of this article (10.1186/s12967-018-1659-4) contains supplementary material, which is available to authorized users.

The glow discharge plasma nitriding of titanium, like that of steels, is usually carried out in cracked ammonia or in a nitrogen-hydrogen gas mixture or, alternatively, in pure nitrogen. The nature of the nitride layers produced is dependent on the gas composition. A study has therefore been made of the effects of using a wide range of nitrogen, nitrogen-hydrogen, and nitrogen-argon mixtures on the structure and composition of the surface layers produced. The problems associated with light element analysis of the resulting titanium nitride coatings were overcome by the use of Rutherford backscattering spectrometry and nuclear reaction analysis (NRA), and nitrogen concentration depth profiles (4-5 üm depth) were obtained. The extent of oxygen contamination was measured using NRA and electron probe microanalysis. X-ray diffraction was used to investigate the degree of preferred orientation in the coatings and also provided information on the amount of various nitride phases present in the coatings (TiN, Ti2N, (α- Ti). Evidence is presented which indicates that the outermost surface layer can consist of a hypernitride of composition TiNx’ where x is ∼ 1·5.

Aim The objective of this systematic review was to evaluate the efficacy of denture adhesives (DAs) in completely edentulous denture wearers compared to not using DAs. Methods and Results PubMed, Web of Science, Cochrane Library, and EMBASE were searched from the database inception up to 6 February 2020 for Randomized Controlled Trials (RCTs) involving patients with complete dentures in both arches where the use of DAs was compared to no use of DAs. A total of 497 abstracts were reviewed, resulting in inclusion of 10 RCTs. Outcomes reported in the included trials were thoroughly reviewed and tabulated. The Cochrane risk of bias tool was used. All 10 studies were assessed at unclear (10%) or high risk of bias (90%). Studies showed DAs improved mainly retention/stability, and masticatory/chewing ability/performance, compared to no adhesives. Conclusion Most studies showed favorable results for DAs on retention and stability of complete dentures, masticatory performance, patient's comfort and satisfaction. Due to the heterogeneity of the outcomes, unclear/high risk of bias and small sample sizes, the quality of the evidence was very low. More high‐quality research is needed with improved blinding and use of standardized methods to evaluate the efficacy of DAs.

Two different methods of surface treatments which employ different mechanisms to produce titanium nitrided surfaces were utilized in this study, namely plasma nitriding of titanium substrate and TiN PVD coating. The surface roughness of the plasma nitrided titanium samples has been found to decrease to a minimum and then increase with increasing temperature. TiN ion plating caused little change to the surface topography, which is generally smoother than plasma nitrided surfaces. Dry sliding and rolling-sliding wear test results were used to evaluate the tribo-oxidation properties of the plasma nitrided and TiN ion plated titanium surfaces in contact with an alumina ball or a similar disc. The present study with regard to oxidative wear has shown that the usefulness of the protective layer on the titanium surface depends mainly on the roughness of the surface. Because of the absence of lubrication it was to be expected that surface finish and the interlocking of asperities would have a greater effect than under lubricated conditions. What was surprising, however, was to find that increasing surface roughness had the opposite effect in the two types of dry test conducted. When a coated surface was rubbed against an alumina ball, the smoothest surface was worn most. However, when the same coated surface in rolling-sliding tests rubbed against another disc with the same coating, the roughest surface was worn most. Nevertheless, none of the coatings tested can be considered resistant to wear without lubrication.