Numerical analysis of reinforced concrete beam subject to pitting corrosion

This paper presents a numerical study about the effects of chloride-induced corrosion on the service life of structures. A two-dimensional geometrically nonlinear mechanical model based on Finite Element Method (FEM) was developed for reinforced concrete structures. The corrosion initiation stage was evaluated by Fick's diffusion laws. The corrosion propagation was carried out by deterministic models based on Faraday's law. Pitting corrosion was simulated in the reinforcements by pit elements, distributed longitudinally on the steel rebars, which degrade the physical properties over time. The service life was determined by the crack width.Two parametric analyses were performed. In the first analysis, five models were created with a variablecover thickness and water/cement ratio (w/c). In the second analysis, the reduction in yield stress due to corrosion was considered.The results showed that the concrete cover thicknessand the w/c ratio significantly influence the service life. The reduction of the cover thickness from 30 mm to 25 mm resulted in 21.26% reduction in service life, whilethe increase in the w/c ratio from 0.50 to 0.55 caused 32.98% reduction in service life of the structural element analyzed.

Convergence analysis and validation of a discrete element model of the human lumbar spine

Degenerative diseases of the spine can lead to or hasten the onset of additional spinal problems that significantly reduce human mobility. The spine consists of vertebral bodies and intervertebral discs. The most degraded are intervertebral discs. The vertebral body consists of a shell (cortical bone tissue) and an internal content (cancellous bone tissue). The intervertebral disc is a complex structural element of the spine, consisting of the nucleus pulposus, annulus fibrosus, and cartilaginous plates. To develop numerical models for the vertebral body and intervertebral disc, first, it is necessary to verify and validate the models for the constituent elements of the lumbar spine. This paper, for the first time, presents discrete elements-based numerical models for the constituent parts of the lumbar spine, and their verification and validation. The models are validated using uniaxial compression experiments available in the literature. The model predictions are in good qualitative and quantitative agreement with the data of those experiments. The loading rate sensitivity analysis revealed that fluid-saturated porous materials are highly sensitive to loading rate: a 1000-fold increase in rate leads to the increase in effective stiffness of 130 % for the intervertebral disc, and a 250-fold increase in rate leads to the increase in effective stiffness of 50 % for the vertebral body. The developed model components can be used to create an L4-L5 segment model, which, in the future, will allow investigating the mechanical behavior of the spine under different types of loading.

A Humanized Monoclonal Antibody Potentiates Killing by Antibiotics of Diverse Biofilm-Forming Respiratory Tract Pathogens

New strategies to treat diseases wherein biofilms contribute significantly to pathogenesis are needed as biofilm-resident bacteria are highly recalcitrant to antibiotics due to physical biofilm architecture and a canonically quiescent metabolism, among many additional attributes. We, and others, have shown that when biofilms are dispersed or disrupted, bacteria released from biofilm residence are in a distinct physiologic state that, in part, renders these bacteria highly sensitive to killing by specific antibiotics. We sought to demonstrate the breadth of ability of a recently humanized monoclonal antibody against an essential biofilm structural element (DNABII protein) to disrupt biofilms formed by respiratory tract pathogens and potentiate antibiotic-mediated killing of bacteria released from biofilm residence. Biofilms formed by six respiratory tract pathogens were significantly disrupted by the humanized monoclonal antibody in a dose- and time-dependent manner, as corroborated by CLSM imaging. Bacteria newly released from the biofilms of 3 of 6 species were significantly more sensitive than their planktonic counterparts to killing by 2 of 3 antibiotics currently used clinically and were now also equally as sensitive to killing by the 3 rd antibiotic. The remaining 3 pathogens were significantly more susceptible to killing by all 3 antibiotics. A humanized monoclonal antibody directed against protective epitopes of a DNABII protein effectively released six diverse respiratory tract pathogens from biofilm residence in a phenotypic state that was now as, or significantly more, sensitive to killing by three antibiotics currently indicated for use clinically. These data support this targeted, combinatorial, species-agnostic therapy to mitigate chronic bacterial diseases.

The crystal structure of TRPM2 MHR1/2 domain reveals a conserved Zn2+-binding domain essential for ligand binding and activity

Transient receptor potential melastatin 2 (TRPM2) is a Ca2+-permeable, non-selective cation channel involved in diverse physiological processes such as immune response, apoptosis and body temperature sensing. TRPM2 is activated by ADP-ribose (ADPR) and 2′-deoxy-ADPR in a Ca2+-dependent manner. While two species-specific binding sites exist for ADPR, a binding site for 2′-deoxy-ADPR is not known yet. Here, we report the crystal structure of the MHR1/2 domain of TRPM2 from zebrafish (Danio rerio) and show binding of both ligands to this domain. We identified a so-far unrecognized Zn2+-binding domain that was not resolved in previous cryo-EM structures and that is conserved in most TRPM channels. In combination with patch clamp experiments, we comprehensively characterize the effect of the Zn2+-binding domain on TRPM2 activation. Our results provide insight into a conserved structural element essential for channel activity.

Design Optimization of a Helical Coil Gas Cooler Based on the Results of CFD Modeling of Erosion Wear

Simulation of erosion wear and design optimization have been performed for a convective gas cooler with a helical coil. Based on the results of simulation of the standard gas cooler design with a flat baffle used in Shell gasification-based combined cycle unit, it is concluded that the particle impact angle is the main factor determining the erosion maximum. To reduce erosion, it is necessary to install a structural element instead of the flat baffle to align the flow path of ash particles at the inlet to the gas cooler. The results of simulation for various baffle shapes show that a hemispherical baffle is optimal. The use of a hemispherical baffle plate made it possible to align the ash particle flow path at the inlet to the gas cooler channels and reduce the maximum level of erosion by a factor of almost 4 compared to the standard geometry of the baffle plate.

Titanium beryllide as an alternative to beryllium in nuclear and thermonuclear engineering, capabilities of UMP JSC in the technology development and beryllides products manufacture

For many decades, beryllium has been used as a structural element in nuclear installations as a moderator / breeder of fast neutrons. The consequence of neutron irradiation is a significant production of gas products in the form of helium and tritium, which leads to swelling and loss of strength properties of beryllium reflectors. The relatively low melting point of beryllium also imposes restrictions on the high-limit temperature regimes of the reactor core. As an alternative to pure beryllium, it is necessary to consider intermetallic compounds based on it, in particular titanium beryllide. Preliminary studies on the thermal desorption of helium and tritium from titanium beryllide have shown that this material has a much lower retention tendency and a lower release temperature. The higher melting point of titanium beryllide compared to pure beryllium is also an advantageous characteristic.Over the past years, UMP JSC, thanks to its research in this area, has achieved significant success in the development of technology for obtaining intermetallic billets and articles based on titanium and chromium beryllides. As a technology demonstrator, prototypes of structural elements of a helium-cooled blanket breeder module of the projected DEMO reactor were made by order of the Karlsruhe Institute of Technology, Germany.The advantages of titanium beryllide, as well as the success achieved in the production of billets and products from it, open up opportunities for a more extensive study of the nuclear, physical and mechanical properties of this material with the possibility of further use in nuclear technology, including thermonuclear reactors, and in high-temperature instrumentation.

ZC3HC1 is a structural element of the nuclear basket effecting interlinkage of TPR polypeptides

The nuclear basket (NB), anchored to the nuclear pore complex (NPC), is commonly thought of as built solely of protein TPR polypeptides, the latter thus regarded as the NB's only scaffold-forming components. In the current study, we report ZC3HC1 as a second building element of the NB. Recently described as an NB-appended protein omnipresent in vertebrates, we now show that ZC3HC1, both in vivo and in vitro, enables in a step-wise fashion the recruitment of TPR subpopulations to the NB and their linkage to already NPC-anchored TPR polypeptides. We further demonstrate that the degron-mediated rapid elimination of ZC3HC1 results in the prompt detachment of the ZC3HC1-appended TPR polypeptides from the NB and their release back into the nucleoplasm again, underscoring the role of ZC3HC1 as a natural structural element of the NB. Finally, we show that ZC3HC1 can keep TPR polypeptides positioned even at sites remote from the NB, in line with ZC3HC1 functioning as a protein connecting TPR polypeptides.

2.2 CuAAC in Peptidomimetics and Protein Mimics

The tremendous recent developments in click chemistry, including the impressive developments of strain-promoted cycloaddition reagents, all started with the copper-catalyzed azide–alkyne cycloaddition (CuAAC) reaction conceived by Meldal et al. and Sharpless et al. This led to a revolution of extremely important applications in the chemical, biological, medical, and materials sciences. It is fair to state that, especially in the synthesis of multifunctional and complex small-to-large biomolecular constructs, CuAAC has been indispensable. This has been particularly evident in the area of peptides, peptidomimetics, and protein mimics. These biomolecules play key roles in the various peptide–peptide, peptide–protein, and protein–protein interactions that are involved in many diseases and disorders, and peptide-based therapeutics can be important in this context. However, it is often important to improve the bioactivity and overall stability, and modulate the spatial structure, of peptide-based therapeutics. The incorporation of the 1,4-disubstituted 1,2,3-triazole moiety as a non-native structural element using CuAAC is explored in this chapter. The resulting incorporated triazole moiety can lead to structural surrogates of the amide bond and disulfide bond. As a consequence, CuAAC can be utilized toward introducing conformational constraints and stabilizing secondary structures of α-helices, β-sheets/turns, or loop-like structures. In addition, CuAAC can be used to combine various peptide sequences with molecular scaffolds to develop protein mimics that can find applications as synthetic vaccines and antibodies.

Diagnostics of the presence of a fatigue crack in the compressor blade using the spectrum of vibration amplitudes at the superharmonic resonance

In this study, the solution of the forced vibration response of a structural element with a fatigue crack was carried out using the finite element method to determine the influence of its presence on the flexural forced vibration behaviour of the compressor blade airfoil at the superharmonic resonance of the order 1/2. The blade airfoil with a low twisted angle was used as an object of investigation to perform the computational analysis. Its vibrations in the plane of minimum stiffness were excited by the kinematic displacement of root edge elements. The fatigue crack was modelled as a mathematical cut. Two locations of the crack were investigated – on the leading edge and convex side of the blade airfoil. The nonlinearity due to the intermittent contact of the crack surfaces, which is caused by the opening and closing of the crack during each vibration cycle, was taken into account by solving the contact problem. To quantify this kind of nonlinear dynamic behaviour, the vibration diagnostic parameter was defined as the displacement amplitude ratio of the dominant harmonics at the superharmonic resonance of the order 1/2. Based on the results of the calculations it has been found that regardless of the crack location, the ratio nature is the same for all vibration axes. However, with vibrations in the plane of minimum stiffness, the crack on the convex side of the airfoil has an opening mode propagation, which makes it possible to fix its location due to a sharp change in the ratio of the amplitudes of the dominant harmonics along the corresponding axis.

A NEW APPROACH TO “THE HOMESTEAD EXEMPTION ACT”- AN ENCOURAGEMENT TO RE-ESTABLISH THE “CASAL DE FAMÍLIA” IN PORTUGUESE LAW

Housing is a fundamental right enshrined in the Constitution. As a structural element of family organisation, the family residence becomes a necessary instrument for achieving the minimum values ​​of human dignity in its family dimension. The Portuguese legal system that constitutionally enshrines the inviolability of the human person's dignity, the protection of the family and the right to housing, attributes a vulnerability to the family residence, allowing it to be seized, with very few exceptions. The "casal de família" institute, which finds its place in the North American Homestead, can recommend a feasible and possible solution to protect the family residence. Under Portuguese law, this institute was in force between 1920 and 1977, assuming the terminology of "casal de família". We will analyse the legal regime of Homestead and the modus operandi of the "casal de família" in Portugal. We wonder whether the Portuguese legal system should again consider the existence of "family property" or "family couple". We believe that such a concept would encourage the family, strengthen its values, strengthen its ties, and solve a pressing social problem, not resolved by the Portuguese law n ° 13/2016, of May 23.