The effect of powder size on the mechanical and corrosion properties and the ignition temperature of WE43 alloy prepared by spark plasma sintering

Powder metallurgy is a powerful method for the preparation of materials with superior properties.This work aimed to investigate the effect of powder size on the microstructure,mechanical,and corrosion properties of advanced WE43(Mg-4Y-3REE-Zr)alloy prepared by spark plasma sintering(SPS).At the same time,the effect of HF pre-treatment of the powder on the properties of final compacted products is studied.Smaller powder particles yielded microstructure with more interfaces formed by Y_(2)O_(3),or MgF_(2) and YF_(3).These interfaces work as barriers against corrosion,which greatly improves corrosion resistance.The suggested pre-treatment of powder in HF further reduced the corrosion rate of the compacted materials.On the contrary,fragile interfaces of YF_(3) decreased mechanical properties as the crack primarily propagates through these interfaces.The original powder containing the mixture of all powder fractions exerted the best combination of mechanical properties.Powder size has also shown to affect ignition temperature.The highest ignition temperature was measured for the finest powder fraction.

Heavy rockbursts due to longwall mining near protective pillars:A case study

Rockburst represents a very dangerous phenomenon in deep underground mining in unfavourable conditions such as great depth, high horizontal stress, proximity of important tectonic structures, and unmined pillars. The case study describes a recorded heavy rockburst in the Czech part of the Upper Silesian Coal Basin, which occurred during longwall mining near the protective pillar. The artificial dividing of geological blocks and creation of mining protective pillars(shaft pillars, crosscut pillars etc.) is a dangerous task in light of rockbursts occurring mainly due to overstressing of remaining pillars. A simple model of this situation is presented. Natural and mining conditions are analysed and presented in detail as well as registered seismicity during longwall mining in the area. Recorded rockbursts in the area of interest are described and their causes discussed. Many rockbursts near protective pillars were recorded in this mining region. Methodical instructions for rockburst prevention in proximity of protective pillars as well as for gates driving were devised based on the evaluation of rockburst causes. The paper presents these principles for prevention.

Extracellular matrix based biomaterials for central nervous system tissue repair: the benefits and drawbacks

Functional repair of injured tissue in the adult central nervous system （CNS） still remains a big challenge for current biomed- ical research and its upcoming clinical translation. The axonal regeneration of the adult CNS is generally low, and it is addi- tionally restricted after injury by the presence of inhibitory mol- ecules, generated by the glial scar.

Identification of the Decay Pathway of Photoexcited Nucleobases

The identification of the decay pathway of the nucleobase uracil after being photoexcited by ultraviolet light has been a long-standing problem.Various theoretical models have been proposed but yet to be verified.Here,we propose an experimental scheme to test the theoretical models of gas phase uracil decay mechanism by a combination of ultrafast x-ray spectroscopy,x-ray diffraction,and electron diffraction methods.Incorporating the signatures of multiple probing methods,we demonstrate an approach that can identify the dominant mechanism of the geometric and electronic relaxation of the photoexcited uracil molecule among several candidate models.

The Digital Agricultural Knowledge and Information System(DAKIS):Employing digitalisation to encourage diversified and multifunctional agricultural systems

Multifunctional and diversified agriculture can address diverging pressures and demands by simultaneously enhancing productivity,biodiversity,and the provision of ecosystem services.The use of digital technologies can support this by designing and managing resource-efficient and context-specific agricultural systems.We present the Digital Agricultural Knowledge and Information System(DAKIS)to demonstrate an approach that employs digital technologies to enable decision-making towards diversified and sustainable agriculture.To develop the DAKIS,we specified,together with stakeholders,requirements for a knowledge-based decision-support tool and reviewed the literature to identify limitations in the current generation of tools.The results of the review point towards recurring challenges regarding the consideration of ecosystem services and biodiversity,the capacity to foster communication and cooperation between farmers and other actors,and the ability to link multiple spatiotemporal scales and sustainability levels.To overcome these challenges,the DAKIS provides a digital platform to support farmers'decision-making on land use and management via an integrative spatiotemporally explicit approach that analyses a wide range of data from various sources.The approach integrates remote and in situ sensors,artificial intelligence,modelling,stakeholder-stated demand for biodiversity and ecosystem services,and participatory sustainability impact assessment to address the diverse drivers affecting agricultural land use and management design,including natural and agronomic factors,economic and policy considerations,and socio-cultural preferences and settings.Ultimately,the DAKIS embeds the consideration of ecosystem services,biodiversity,and sustainability into farmers'decision-making and enables learning and progress towards site-adapted small-scale multifunctional and diversified agriculture while simultaneously supporting farmers'objectives and societal demands.