In our previous work we reported the impact of hydrofluoric and nitric acid used for chemical polishing of Ti-6Al-7Nb scaffolds on decrease of the number of Staphylococcus aureus biofilm forming ...cells. Herein, we tested impact of the aforementioned substances on biofilm of Gram-negative microorganism, Pseudomonas aeruginosa, dangerous pathogen responsible for plethora of implant-related infections. The Ti-6Al-7Nb scaffolds were manufactured using Selective Laser Melting method. Scaffolds were subjected to chemical polishing using a mixture of nitric acid and fluoride or left intact (control group). Pseudomonal biofilm was allowed to form on scaffolds for 24 hours and was removed by mechanical vortex shaking. The number of pseudomonal cells was estimated by means of quantitative culture and Scanning Electron Microscopy. The presence of nitric acid and fluoride on scaffold surfaces was assessed by means of IR and rentgen spetorscopy. Quantitative data were analysed using the Mann-Whitney test (P ≤ 0.05). Our results indicate that application of chemical polishing correlates with significant drop of biofilm-forming pseudomonal cells on the manufactured Ti-6Al-7Nb scaffolds ( p = 0.0133, Mann-Whitney test) compared to the number of biofilm-forming cells on non-polished scaffolds. As X-ray photoelectron spectroscopy revealed the presence of fluoride and nitrogen on the surface of scaffold, we speculate that drop of biofilm forming cells may be caused by biofilm-supressing activity of these two elements.
WOCAT – The World Overview of Conservation Approaches and Technologies with its unique methodology and global Sustainable Land Management (SLM) database - can help promote scaling out of SLM and thus ...contribute to land degradation neutrality. This paper focuses primarily on three Land Degradation Neutrality (LDN) indicators: (i) land cover, (ii) land productivity and (iii) carbon stocks. It is demonstrated what can be achieved by analyzing SLM practices in the database and how these shed light on the LDN indicators. Different stages of interventions - from prevention (avoiding), to reduction (reducing), and restoration (reversing) of Land Degradation (LD) - are differentiated and analyzed. This highlights the fact that most efforts and achievements recorded by WOCAT focus on reducing and preventing LD: that stands in contrast to the current emphasis by many policy makers on the much more costly task of restoration. The use of the WOCAT-LADA (Land Degradation Assessment) mapping approach is illustrated, with a case study from Madagascar. Understanding and integrating mosaic pieces at the local level can help in comprehending impacts at the national and global levels as observed by remotely sensed imagery. Supporting land users with financial resources, an enabling legal framework and, in particular with knowledge and information about SLM practices is a logical and promising way forward to promoting adoption of SLM and, eventually, reaching LDN. With respect to creating an enabling environment for scaling out SLM and supporting land users, the analysis reveals that knowledge is the second greatest constraint after financial resources. This implies that further investment must be made in capacity building and sharing knowledge on impacts of SLM, costs-benefits and the spatial spread of SLM. Furthermore, this knowledge should be linked to a clear SLM mainstreaming and scaling out strategy, which will support countries to reach their LDN targets. A decision support framework was developed by the Food and Agriculture Organization of the United Nations (FAO) and WOCAT which guides countries in LD and SLM assessments, and the use of the results for formulating and informing SLM mainstreaming and scaling out.
Selective laser melting (SLM) technologies are becoming increasingly popular. The aim of the work is to compare the metallographic structure, hardness, and selected strength properties of alloys ...obtained by casting and by SLM, with a particular emphasis on fatigue strength. Twenty Cr/Co alloy bars were made by casting or SLM, and samples of appropriate dimensions were prepared for individual tests. The microstructures of the samples were tested by metallography, and then tested for hardness, impact strength, tensile strength, bending strength, and fatigue strength; they were also subjected to fracture after bending, tensile, fatigue, and impact tests, with the resulting fractures examined by scanning electron microscopy (SEM). Primary dendrites and small amounts of gas bubbles were present in the cast samples ground lengthwise. The SEM samples were more finer grained and uniform. Compared to the casting samples, the SLM samples demonstrated higher hardness, lower mean impact strength and higher tensile strength. The casting samples also displayed lower mean elongation values. The casting samples demonstrated slightly higher fatigue strength. The fractures of the casting samples showed an interdendritic character with clearly visible dendrites at the fracture, while those of the SLM samples were also intergranular, but finer grained. SLM generally results in better strength properties, while casting obtains slightly greater fatigue strength.
The services provided by ecosystems play a vital role in human well-being. As they are indispensable for maintaining development as well as for future economic and social growth of the society. Many ...analytic-deliberative techniques have been suggested as a promising approach to ecosystem services valuation but still they are in many countries on an experimental stage. The aim of this study is an impact assessment on ecosystem services, which is being carried out on the Myjava River basin where we address the problem of soil protection against floods and water erosion through SLM technologies, e.g. focusing mainly on changes in vegetation cover. Our assessment is based on a methodology based on combination of the division and group from CICES classification within our plot level Myjava River basin and also regional level of Myjava region focusing on the provision, regulating and cultural ecosystem services. The results of this study can be used by the development of the soil protection plans for reducing flood, and water erosion.
In this work, we try to solve the problem of laser-induced thermal aberrations appearance in selective laser melting (SLM) machines. In order to do this, we propose to use a shielding window ...consisting of materials with a nanostructured surface layer instead of standard. Because of the self-cleaning effect, this substitution may allow to lessen its contamination, influencing laser radiation distortion. The comparative study made in this work shows that nanostructured glasses may be promising candidates for shielding windows allowing lessening thermal lens effect.
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