STRUCTURE AND PHASE COMPOSITION OF COATING ON EP718 ALLOY AFTER HOT-DIP ALUMINIZING

The results of studies of the structure, chemical and phase composition of the aluminide coating formed on the surface of EP718 alloy after its hot-dip aluminizing are presented. It is shown that the inner layer of the coating consists of a continuous layer of a solid solution based on chromium aluminide CrAl with a monoclinic lattice, in which some of the Cr atoms are replaced by atoms of elements from the EP718 alloy, and the outer layer, which has a pronounced heterogeneous structure, is an aluminum matrix with inclusions of CrAl aluminide. with a lower aluminum content.

Analytical Solutions for Girder Distribution Factor in Steel-Concrete Composite Girders with the Effect of Parapets

The existing studies have shown that parapets have great influence on the girder distribution factor (GDF) of bridges. However, there is no method in the design guide to estimate the GDF considering the effect of parapets. This research aims to develop a simplified method for estimating the GDF by considering the effect of parapets. First, a simply supported steel-concrete composite girder bridge was tested to investigate the effect of parapets on the GDF. Then, finite-element (FE) model was established and verified by the field test data of strain and deflection. In addition, error study showed that the bending stiffness of the bridge was increased by about 92% and 19.1%, respectively, due to the effects of parapet and continuous layer. As the effect of the continuous layer on each girder was relatively uniform, the simplified method was optimized only considering the effect of the parapet. Finally, the effect of the parapet on the GDF was compared and discussed. Considering the effect of the parapet, the GDF of the exterior girder calculated by the simplified method and FE analysis decreased by about 26.92% and 23.53%, respectively, and the adjacent interior girder decreased by about 15.22% and 12.77%, respectively. Comparing the GDF calculated by the AASHTO LRFD specifications, the GDF calculated by the simplified method decreased by about 30.77% in the exterior girder and 41.30% in the interior girder, respectively. The results indicate that the method of calculating the GDF without considering the effect of the parapet in AASHTO LRFD specifications is conservative. The GDF calculated by the simplified method was basically close to the field test results, meaning that the proposed simplified method considering the effect of the parapet was relatively accurate.

Oxidation Behavior of Quaternary Co-20Re-25Cr-3Si Alloy at Laboratory Air

The iso-thermal oxidation of the quaternary Co-20Re-25Cr-3Si alloy at 1,000–1,200 C under laboratory air for 24 h has been studied. The oxidation kinetics at 1,000–1,200 C follow parabolic law perfectly and the value of oxidation activation energy is 220.74 kJ/mol. Unlike the experimental condition of 0.1 MPa pure oxygen, under laboratory air Co-20Re-25Cr-3Si alloy presents a good oxidation resistance due to the formation of a dense and continuous layer of Cr2O3 in contact with the alloy. A 79% drop in oxygen pressure has changed the oxidation mode from catastrophic oxidation to mild oxidation. The thickness of the protective Cr2O3 layer decreases when temperature increases. Therefore, Co-20Re-25Cr-3Si alloy shows the best oxidation resistance at 1,000 C. Moreover, from another perspective, compared with Co-17Re-23Cr-3Si alloy, the addition of about 2% Cr can also improve the oxidation resistance of the alloy greatly by forming the protective Cr2O3 layer.

Tumour-associated Angiogenesis and Intermediate Blood Vessels in Renal Cell Carcinoma

Background/Aim: Renal cell carcinoma is strongly vascularized, and formation of new blood vessels is a complex and multi-step process. In this study, we analysed the subtypes of intermediate blood vessels, as shown by double immunohistochemistry. Materials and Methods: Tumour-associated blood vessels were identified by double immunostaining based on CD34 and smooth muscle cell actin. Blood vessels were classified both quantitatively and qualitatively based on the expression of the aforementioned two markers. The main criteria to sub-classify intermediate blood vessels was the presence, distribution, and arrangement of perivascular cells. Results: We described three subtypes of intermediate blood vessels found particularly in the tumour area: Subtype 1 lacked perivascular cells, subtype 2 showed scattered pericytes attached to the vascular wall, and subtype 3 showed a continuous layer of perivascular cells on one side. Conclusion: We describe for the first time three subtypes of renal cell carcinoma-associated intermediate blood vessels, which could be important in prognosis and as potential targets for anti-vascular therapy.

Tiny, ornamented eggs and eggshell from the Upper Cretaceous of Utah represent a new ootaxon with theropod affinities

A new Cretaceous ootaxon (eggshell type) from the Kaiparowits Formation of Grand Staircase-Escalante National Monument is among a growing number of very small eggs described from the Mesozoic. Analyses of two partial eggs (~ 17.7 mm in diameter) and 29 eggshell fragments reveal that this new ootaxon exhibits nodose ornamentation with distinctive branching pore canals that open atop the nodes. Its two-layered microstructure consists of a mammillary layer and a continuous layer with rugged grain boundaries between calcite grains. Although the exact identity of the egg producer is unknown, the eggshell microstructure and small size is consistent with a small-bodied avian or non-avian theropod. The specific combination of small egg size, branching pores, two-layered microstructure, and dispersituberculate ornamentation preserved in this new ootaxon is unique among theropod eggs. This underscores that both eggshell and skeletal fossils of Cretaceous theropods can display a mosaic of transitional morphological and behavioural features characteristic of both avian and non-avian taxa. As such, this new ootaxon increases the diversity of Cretaceous eggs and informs our understanding of the evolution of theropod eggshell microstructure and morphology.

Structure, Assembly and Function of Cuticle from Mechanical Perspective with Special Focus on Perianth

This review is devoted to the structure, assembly and function of cuticle. The topics are discussed from the mechanical perspective and whenever the data are available a special attention is paid to the cuticle of perianth organs, i.e., sepals, petals or tepals. The cuticle covering these organs is special in both its structure and function and some of these peculiarities are related to the cuticle mechanics. In particular, strengthening of the perianth surface is often provided by a folded cuticle that functionally resembles profiled plates, while on the surface of the petal epidermis of some plants, the cuticle is the only integral continuous layer. The perianth cuticle is distinguished also by those aspects of its mechanics and development that need further studies. In particular, more investigations are needed to explain the formation and maintenance of cuticle folding, which is typical for the perianth epidermis, and also to elucidate the mechanical properties and behavior of the perianth cuticle in situ. Gaps in our knowledge are partly due to technical problems caused by very small thicknesses of the perianth cuticle but modern tools may help to overcome these obstacles.

Theoretical prerequisites for improving the body low loader granular fertilizer spreader

It is known that the use of granular forms of fertilizers is a universal solution for plant growing enterprises using organic, mineral, organomineral fertilizers in their activities. For crop farming enterprises, the application of granular fertilizers is the most convenient way to enrich the soil with nutrients. For the surface main application and top dressing, spreaders of different designs are used, distributing fertilizers in a continuous layer with different indicators of uniformity. At present, the development of machines of various designs is underway to operate applying solid fertilizers. The main tasks of research by various authors in the field of mechanization of the distribution of fertilizers over the surface of the field are to reduce the uneven distribution of fertilizers across the width, increase the sowing width, as well as reduce the changeover time for the fertilization operation. The article presents studies related to the improvement of the design of the working bodies of the machine for applying granular fertilizers, installed on the horizontal axis of rotation. To achieve the goal of increasing the working width of the unit without reducing the quality of the sifting, an option was proposed to supplement the design of a low-frame body spreader for solid fertilizers.

Preparation of Polypyrrole/Polyurethane Foam Composite Material

Firstly, the paper focused on the polyurethane foam soaking process with pyrrole solution, and discuss the estimated electro-mechanical properties of the modified PU foam. Secondly, scanning electron microscopy (SEM) micrographs were collected to understand the polypyrrole distribution inside the foam. The results show that the chemical polymerisation parameters needed to realise this amount of polypyrrole in the foam were 0.1 mol/L of pyrrole, a mole ratio of 1:2.25, an oxidation temperature of 12 ± 3 °C, and an oxidation time of 2 hours. SEM images of the samples prepared with the modified approach showed a continuous layer of about 10-15 μm thickness of the polypyrrole attached to the surface of the PU foam.

FORMATION OF THE INTERACTION ZONE AT THE INTERLAYER BOUNDARY OF THE EXPLOSION-BOILED COMPOSITE VT1-0 + MH45 IN CONTACT MELTING

It is shown that the replacement of the MH19 alloy with the MH45 alloy in the explosion-welded layered titanium-copper-nickel composite leads to a decrease in the temperature at which the liquid (metal melted by contact melting) is in equilibrium with the solid phases from 930 ° C (L↔TiCuNi + NiTi + CuTi) up to 860 ° C (L↔ TiCu+NiTi+TiNi); to a change in the mechanism of contact melting from diffusion to diffusion; to increase the proportion of titanium in the interaction zone from ~ 50 at.% to ~ 66 at.%. The development of the contact melting process at the interlayer boundary of the VT1-0 + MH45 layered composite after the solid solution is transformed into a liquid phase film leads to the formation of an interaction zone with the phase composition TiCuNi, TiNi (Cu), TiCu (Ni), TiNi (Cu) TiCu (Ni) . On the side of the MH45 alloy, a continuous layer of the ternary intermetallic TiCuNi adjoins it, and on the titanium side, αTi + TiNi (Cu).