The aim of the article is to analyze the structure and mechanical properties in terms of the cracking mechanics of geopolymer composites based on fly ash and river sand, as well as metakaolin and river sand with three types of reinforcement material: glass fiber, carbon fiber, and aramid fiber, in terms of their use in additive manufacturing. Geopolymer composites were reinforced with fibers in a volume ratio of 0.5%, 1.0%, and 2.0%. Subsequently, these samples were subjected to bending strength tests in accordance with the European standard EN 12390-3. The addition of fibers significantly improved the bending strength of all composites made of metakaolin and sand. The reinforcement with aramid fiber in the amount of 2.0% resulted in more than a 3-fold increase in strength compared to the reinforcement-free composites. An analysis of the morphology of the fibers was carried out on the basis of photos taken from an electron microscope. The correct addition of fibers changes the nature of the fracture from brittle to more ductile and reduces the number of cracks in the material.

The exposure of winter triticale to cold promotes genotype-dependent resistance to fungal pathogen. We present the evidence that structural and chemical modifications of the cell wall components induced by cold can be correlated with the resistance against fungal infection. Our results showed that cellulose of hardened triticale cv. Hewo (able to develop resistance after cold treatment) has more compact and integrated structure, thicker and longer fibres when compared to cv. Magnat (susceptible to fungal infection despite plant hardening). Such structure of cellulose limits water sorption, favours stronger bonding the water of crystallisation to macromolecules, impedes depolymerisation process during decomposition, and finally results in higher thermal stability of cell wall. Furthermore, the lignin composition is drastically modified in resistant plants. Pattern of the thermal decomposition indicates higher molecular mass and more complex structure of lignin, followed by the higher thermal stability. We conclude that specific structure of lignocellulosic cell wall of the resistant plants forms a barrier for fungal enzymes digesting host tissue as well as can resist better the mechanical pressure of hyphae.

The influence of nickel addition to tin substrate on microstructure, kinetics parameters as well as diffusion coefficients was studied on Cu/Sn diffusion couples. The results revealed that the presence of nickel did not affect the growth of Cu₃Sn phase in comparison with that of the binary Cu/Sn diffusion couple. However, it substantially influenced the morphology and chemical composition of the (Cu_1−xNi_x)₆Sn₅ phase, which grew with dual morphology and different chemical composition. The layer of the phase was poorer in nickel, whereas detached grains were richer in nickel concentration. The calculated kinetic parameters showed that the growth of the Cu₃Sn and Ni-poor (Cu_1−xNi_x)₆Sn₅ phases was controlled by volume diffusion, but in the case of Ni-rich (Cu_1−xNi_x)₆Sn₅ phase, the growth was controlled by a complex mechanism. The calculations of diffusion coefficients and activation energies of Cu₃Sn and Ni-poor (Cu_1−xNi_x)₆Sn₅ phases revealed that the presence of nickel in the tin substrate did not affect the rate of formation/growth of those phases in comparison with the binary Cu/Sn diffusion couples.

Micromachining plays a vital role in the manufacturing industry in producing microcomponents with high sensitivity and fine dimensional tolerances for implant materials in medical applications. Micro-machining can be carried out through various machining processes like physical, chemical and biological processes, although the use of biological machining is limited. In biological machining, microorganisms are used as a source of energy to machine the components, and machining with microorganism brings a lot of advantages in the machining process like the production of components with lower energy resources, low cost, no heat-affected zone and fine dimensional tolerances, which makes it suitable for machining implant materials. In other machining process like conventional and unconventional machining processes, the heat-affected zone, dimensional tolerances and environmental-related problems are the major issues, as these processes generate more heat while machining. This damages the material, which will not be able to be used for certain applications, and this issue can be overcome by bio-machining. In this present work, nickel, titanium and nitinol are manufactured using the powder metallurgy technique. They are manufactured as a 10 mm diameter and 5 mm thick pellet. The fabricated nickel, titanium and nitinol shape memory alloys are machined with Acidithiobacillus ferrooxidans microorganisms to obtain a better material removal rate and surface roughness and to check the bio-machining performance by considering various parameters such as shaking speed, temperature, pH and percentage of ferric content for the future scope of biomedical applications. Considering these parameters, microorganisms play a vital role in the temperature, shaking speed and time of the bio-machining process, and it was observed that a better material removal rate and surface roughness are achieved at a temperature of 30 °C, shaking speed of 140 rpm and machining time of 72 h.