The article presents the investigation results of titanium alloy Ti6Al4V surface layer after laser melting process. The process of laser melting was performed using Nd-YAG laser. The evaluation of ...structure of the alloy as well as hardness and chemical composition was performed. It was shown that laser melting changes the structure and properties of titanium alloy Ti6Al4V and process parameters as scanning speed affects the thickness of zones in top layer of the material. Due to the laser melting process more wear resistive surface can be obtained that increases the wear and corrosion resistance of orthopeadic prosthesis.
Biocompatibility and Bioactivity of Load-Bearing Metallic Implants The main objective of here presented research is to develop the titanium (Ti) alloy base composite materials possessing better ...biocompatibility, longer lifetime and bioactivity behaviour for load-bearing implants, e.g. hip joint and knee joint endoprosthesis. The development of such materials is performed through: modeling the material behaviour in biological environment in long time and developing of new procedures for such evaluation; obtaining of a Ti alloy with designed porosity; developing of an oxidation technology resulting in high corrosion resistance and bioactivity; developing of technologies for hydroxyapatite (HA) deposition aimed at composite bioactive coatings; developing of technologies of precipitation of the biodegradable core material placed within the pores. The examinations of degradation of Ti implants are carried out in order to recognize the sources of both early allergies and inflammation, and of long term degradation. The theoretical assessment of corrosion is made assuming three processes: electrochemical dissolution through imperfections of the anodic oxide layer, diffusion of metallic ions through the oxide layer, and dissolution of oxides themselves. In order to increase the biocompatibility, the toxic elements, aluminium (Al) and vanadium (V) are eliminated. The experiments have shown that titanium - zirconium - niobium (Ti-Zr-Nb) alloy may be a such a material which can also be prepared by both powder metallurgy (P/M) technique and selective laser melting. The porous (scaffold) Ti-Zr-Nb alloy is now obtained by powder metallurgy, classical and with space holders used before melting and decomposed, or remained during melting and removed by subsequent water dissolution. The oxidation of porous materials is performed either by electrochemical technique in special electrolytes or by chemical and/or hydrothermal method in order to obtain the optimal oxide layer well adjacent to an interface, preventing the base metal against corrosion and bioactive because of its nanotubular structure, permitting injection of some species into the pores. The Ca, O and N ion implantation or deposition of zirconia sublayers may be used to increase the biocompatibility, bioactivity and corrosion resistance. The HA coating obtained by either electrophoretic, biomimetic or by sol-gel deposition should result in gradient structure similar to bone structure, possessing high adhesion strength. The core material of the porous material should result in a biodegradable material, allowing slower dissolution followed by stepwise growth of bone tissue and angiogenesis, preventing local inflammation processes, sustaining the mechanical strength close to that of non-porous material.
Abstract Study question Is AI-based evaluation of embryos as effective in achieving pregnancy as the standard assessment performed by an experienced embryologist? Summary answer AI-based assessment ...of blastocysts may result in comparable pregnancy rates as the standard assessment performed by an experienced embryologist. What is known already Standard clinical practice in the IVF procedure includes morphological assessment of blastocysts based on visual evaluation following Gardner scale. However, this subjective grading process is susceptible to variability dependent on the professionals’ experience and knowledge, leading to potential inconsistencies in selecting embryos for transfer. Recently, there has been a suggestion that artificial intelligence (AI) algorithms could enhance the predictability of treatment outcomes and many AI-based software applications have been introduced to the procedure in many IVF centers. Nevertheless, there are very few prospective evaluations of the real-life implementation of the novel technologies. Study design, size, duration It is an ongoing, randomized, prospective, multicenter, international study performed in four investigation centers since November 2023. The duration of the study is scheduled for one year. Participants/materials, setting, methods The first stage of the evaluation comprises a randomized selection of a patient meeting the inclusion criteria to one of the groups: test or control group. The next step includes a selection of the embryo for implantation. For the control group, the experienced embryologist performs the standard selection of embryos as per normal clinical practice following the Gardner scale. For the study group, the embryologist selects the embryo for transfer indicated by the EMBRYOAID application. Main results and the role of chance Currently, there have been 149 patients recruited in the study and 160 cycles with 638 embryos have been entered in the EMBRYOAID software for AI-based evaluation. Test group of 80 patients comprises 87 cycles with 346 embryos. Preliminary results of the prospective study conducted in real-life settings show encouraging outcomes in relation to the idea that AI-supported embryo evaluation may be as effective in regards to obtaining pregnancy as a standard clinical assessment performed by experienced professionals. Nevertheless, the sample size is not yet sufficient to achieve statistical significance. Therefore, further data gathering will be conducted and the study hypothesis will be furthermore examined. Limitations, reasons for caution The sample size is still insufficient to reach statistical significance and the study shows the preliminary results which will be further verified on a larger patient group. Wider implications of the findings Results of a prospective, randomized trial conducted in several international clinics may enhance the trend to introduce more objective, bias-free AI-based tools into the embryology labs. Trial registration number EMBRYO National Center for Research and Development nr POIR.01.01.01-00-1631/20-00; ERC Consolidator Grant TUgbOAT no 772346
The first records of Sticta andina and S. scabrosa subsp. scabrosa from Bolivia are presented. All records are confirmed by molecular data. Sticta andina has flattened, marginal isidia and phyllidia ...with abundant, submarginal apothecia, while tomentum is dark brown to black, whereas, S. scabrosa subsp. scabrosa has marginal and laminal phyllidia and pale to dark, grey tomentum. Two Bolivian specimens of the latter possess sparse, marginal to laminal apothecia, which previously have not been observed in this species. The haplotype network indicates that the S. andina specimens from Bolivia have three haplotypes, two of which are different from those previously reported. In the case of S. scabrosa subsp. scabrosa, two haplotypes were found, of which one is newly reported. A distribution map of Sticta species confirmed for Bolivia is presented.
In conventional interferometric synthetic aperture radar (SAR), the coherent combination of two SAR images reconstructed from two separated receive antennas is used for digital elevation model (DEM) ...or moving target indication (MTI), depending on the antenna constellations. In this paper we propose the novel system concept for interferometric SAR (InSAR) based on Multiple-Input Multiple-Output (MIMO) configuration. A digital beam forming (DBF) SAR system based on multiple receive antennas is extended to MIMO SAR concepts. We investigate its performance and processing features, particularly, associated with the received signal quality and the transmitter diversity. Using orthogonal linear frequency modulated (LFM) signal, it is shown that space-time coding scheme can be applied to SAR system in multiple-input single-output (MISO) configuration. A simple Alamouti scheme enhances the signal-to-noise ratio (SNR) and extracts a spatial diversity. Combining this transmitter spatial diversity and digital beam forming on receive, we introduce the potential of high resolution wide swath (HRWS) observation for Interferometry.
The hybrid mode provides radar images with resolution better than in stripmap mode with swath length longer than in the spotlight mode. In the paper described is a processor for hybrid radar data. ...The algorithm bases on the chirp scaling algorithm. In order to process the hybrid mode data an azimuth filter is applied before the chirp scaling algorithm.
High-Resolution Wide-Swath (HRWS) Synthetic Aperture Radar (SAR) is a multi-static spaceborne Radar. The performance of the Radar system is improved by the mean of DBF on receive in azimuth and in ...elevation. This requires an relieve antenna array with large number of elements. In this paper the performance of large antenna array under the influence of plane distortions is analyzed. Presented is the influence on the array factor of symmetrical, unsymmetrical and random mechnical distortion. The paper considers also the influence on the performance of the antenna distortion on the High-Resolution Wide-Swath (HRWS) Synthetic Aperture Radar (SAR) in elevation.
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