Volume 16 (2016): Issue 4 (December 2016)

The article presents the idea of the use of Temper Bead Welding (TBW) technique to improve the weldability of high strength steel at underwater wet welding conditions. Wet welding method with the use of covered electrodes is described. This work shows results of metallographic examinations and hardness measurements of samples of S420G2+M steel with weld beads performed under water. It has been shown that Temper Bead Welding technique may provide a way to reduce the hardness of the welds, thus is a useful method for improving weldability of high strength steel welded in underwater conditions. The optimum overlap of weld beads (pitch) was set of 55÷100%.

In this effort, blend membrane of polycarbonate (PC) and polypropylene-graft-maleic anhydride (PPMA) was fabricated via phase inversion technique. The nano-zeolite (NZ) was employed as nanofiller. Morphology of PC/PPMA/NZ membrane revealed unique inter-connected branched microstructure. Tensile strength and Young’s Modulus of PC/PPMA/NZ 0.1-5 were in the range of 59.9-74.5 MPa and 111.4-155.2 MPa respectively. The nano-zeolite filler was also effective in enhancing the permselectivity αCO₂/N₂ (23.5 to 38.5) relative to blend membrane (20.3). The permeability P_CO2 of PC/PPMA/NZ 5 membrane was found as 106.2 Barrer. Filler loading enhanced gas diffusivity, however filler content did not significantly influence CO₂ and N₂ solubility.

The present work is a review of publications covering computer simulation of aortic valve operation and material properties of aortic valve components studies. Particular attention is paid to the anisotropy of material and geometric properties. The methods of geometric models developing by using specified research methods and/or diagnostic imaging devices are presented. The microstructure of the aortic valve is also described and its impact on material properties definition introduced. The various ways of describing the aortic valve leaflet anisotropic properties are mentioned. Often exploited simplifications and their impact on the simulation results is also presented.

Microstructure transformations occur in the Manaurite XM cast steel tubes during long-term operation in the reformer furnace were revealed and described. The relationship between mechanical properties, an increase of internal diameter of the tube and microstructure degradation is discussed. Static tensile test was performed on two types of samples with different shapes. It has been shown differences in the results of tests and an explanation of this phenomenon.

Bacterial nanocellulose (BNC) is a nanofibrilar polymer produced by strains such as Gluconacetobacter xylinus, one of the best bacterial species which given the highest efficiency in cellulose production. Bacterial cellulose is a biomaterial having unique properties such as: chemical purity, good mechanical strength, high flexibility, high absorbency, possibility of forming any shape and size and many others. Such a large number of advantages contributes to the widespread use of the BNC in food technology, paper, electronic industry, but also the architecture in use. However, the greatest hopes are using the BNC in medicine. This text contains information about bacterial nanocellulose, its specific mechanical and biological properties and current applications.