A prometaphase mechanism of securin destruction is essential for meiotic progression in mouse oocytes

Successful cell division relies on the timely removal of key cell cycle proteins such as securin. Securin inhibits separase, which cleaves the cohesin rings holding chromosomes together. Securin must be depleted before anaphase to ensure chromosome segregation occurs with anaphase. Here we find that in meiosis I, mouse oocytes contain an excess of securin over separase. We reveal a mechanism that promotes excess securin destruction in prometaphase I. Importantly, this mechanism relies on two phenylalanine residues within the separase-interacting segment (SIS) of securin that are only exposed when securin is not bound to separase. We suggest that these residues facilitate the removal of non-separase-bound securin ahead of metaphase, as inhibiting this period of destruction by mutating both residues causes the majority of oocytes to arrest in meiosis I. We further propose that cellular securin levels exceed the amount an oocyte is capable of removing in metaphase alone, such that the prometaphase destruction mechanism identified here is essential for correct meiotic progression in mouse oocytes.

CHEMICAL CORROSION PROCESSES OCCURRING IN THE MATERIAL OF LARGE-BLOCK POROUS CERAMICS

Large-block porous ceramics, which enter the market of building materials, have a number of undeniable qualities: low thermal conductivity, low density, high aesthetic qualities. According to its design features, this material is a modern prototype of hollow bricks used in construction since the nineteenth century. Field studies of the work of enclosing structures using hollow bricks have shown that in many cases, the bricks laid in the enclosing structures of buildings 60-80 years ago were significantly destroyed. In this case, the destruction mechanism does not depend on the polythermal load on the material. The hypothesis that the destruction is associated with the chemical destruction of the material was investigated using the developed method for determining the chemical resistance of the material of wall ceramics. The conducted studies confirmed the hypothesis. Studies of the chemical resistance of the material of large-block porous ceramics should be taken into account in the production technology of ceramics.

REVISITING THE CONFIRMATION OF THE IDENTITY OF THE CORROSION DESTRUCTION MECHANISM OF ALUMINUM ALLOYS (review) Part 2. Corrosion in sea water

The paper presents an overview of studies of the corrosion destruction mechanisms of aluminum alloys in seawater. The main factors that have the greatest impact on corrosion are considered: physical and chemical parameters, the depth of the test objects, as well as the role of biofouling. It has been determined that the parameter of the species composition of the fouling organisms is an important factor in the corrosion of metals in seawater and should be taken into account when identifying the mechanism of corrosion destruction during tests under various conditions.

Design, Simulation, and Experimental Verification of a Destruction Mechanism of Transient Electronic Devices

To quickly destroy electronic devices and ensure information security, a destruction mechanism of transient electronic devices was designed in this paper. By placing the Ni-Cr film resistance and the energetic material between the chip and the package and heating the resistance by an electric current, the energetic material expanded and the chip cracked. The information on the chip was destroyed. The author simulated the temperature distribution and stress of the power-on structure in different sizes by ANSYS software. The simulation results indicate that the chip cracks within 50 ms under the trigger current of 0.5 A when a circular groove with an area of 1 mm2 and depth of 0.1 mm is filled with an expansion material with an expansion coefficient of 10−5°C−1. Then, the author prepared a sample for experimental verification. Experimental results show that the sample chip quickly cracks and fails within 10 ms under the trigger current of 1 A. The simulation and experimental results confirm the feasibility of the structure in quick destruction, which lays the foundation for developing instantaneous-failure integrated circuit products to meet information security applications.

Experimental Analysis of Perimeter Shear Strength of Composite Sandwich Structures

The work concerns the experimental analysis of the process of destruction of sandwich structures as a result of circumferential shearing. The aim of the research was to determine the differences that occur in the destruction mechanism of such structures depending on the thickness and material of the core used. Specimens with a Rohacell foam core and a honeycomb core were made for the purposes of the research. The specimen destruction process was carried out in a static loading test with the use of a system introducing circumferential shear stress. The analysis of the tests results was made based on the load-displacement curves, the maximum load, and the energy absorbed by individual specimens. The tests indicated significant differences in the destruction mechanism of specimens with varied core material. The specimen with the honeycomb core was characterized by greater stiffness, which caused the damage to occur locally in the area subjected to the pressure of the punch. In specimens with the foam core, due to the lower stiffness of that core, the skins of the structure were bent, which additionally transfers compressive and tensile loads. This led to a higher maximum force that the specimens obtained at the time of destruction and greater energy absorption.

Role of Bcl-2 Family Proteins in Photodynamic Therapy Mediated Cell Survival and Regulation

Photodynamic therapy (PDT) is a treatment modality that involves three components: combination of a photosensitizer, light and molecular oxygen that leads to localized formation of reactive oxygen species (ROS). The ROS generated from this promising therapeutic modality can be lethal to the cell and leads to consequential destruction of tumor cells. However, sometimes the ROS trigger a stress response survival mechanism that helps the cells to cope with PDT-induced damage, resulting in resistance to the treatment. One preferred mechanism of cell death induced by PDT is apoptosis, and B-cell lymphoma 2 (Bcl-2) family proteins have been described as a major determinant of life or death decision of the death pathways. Apoptosis is a cellular self-destruction mechanism to remove old cells through the biological event of tissue homeostasis. The Bcl-2 family proteins act as a critical mediator of a life–death decision of cells in maintaining tissue homeostasis. There are several reports that show cancer cells developing resistance due to the increased interaction of the pro-survival Bcl-2 family proteins. However, the key mechanisms leading to apoptosis evasion and drug resistance have not been adequately understood. Therefore, it is critical to understand the mechanisms of PDT resistance, as well as the Bcl-2 family proteins, to give more insight into the treatment outcomes. In this review, we describe the role of Bcl-2 gene family proteins’ interaction in response to disease progression and PDT-induced resistance mechanisms.

The Influence of the Structure on the Destruction Mechanism of Polymer-Cement Plaster Coating

The article considers the influence of the structure of polymer-cement plaster coating on the nature of its destruction during the operation of the wall structure. It was shown that the use of purposefully selected components of the mixture (RPP, polymer fiber, cellulose ethers, fine aggregate with a low modulus of elasticity, etc.) made it possible to increase the uniformity of its structure and contact area with masonry, reduce the number of cracks during hardening, and slow down their development during operation, increase the durability of it and the wall structure. The durability of the wall structure largely depends on the number of defects in the plaster coating and the contact area between it and the masonry.

Rotational Disruption of Astrophysical Dust and Ice—Theory and Applications

Dust is an essential component of the interstellar medium (ISM) and plays an important role in many different astrophysical processes and phenomena. Traditionally, dust grains are known to be destroyed by thermal sublimation, Coulomb explosions, sputtering, and shattering. The first two mechanisms arise from the interaction of dust with intense radiation fields and high-energy photons (extreme UV), which work in a limited astrophysical environment. The present review is focused on a new destruction mechanism present in the dust-radiation interaction that is effective in a wide range of radiation fields and has ubiquitous applications in astrophysics. We first describe this new mechanism of grain destruction, namely rotational disruption induced by Radiative Torques (RATs) or RAdiative Torque Disruption (RATD). We then discuss rotational disruption of nanoparticles by mechanical torques due to supersonic motion of grains relative to the ambient gas, which is termed MEchanical Torque Disruption (METD). These two new mechanisms modify properties of dust and ice (e.g., size distribution and mass), which affects observational properties, including dust extinction, thermal and nonthermal emission, and polarization. We present various applications of the RATD and METD mechanisms for different environments, including the ISM, star-forming regions, astrophysical transients, and surface astrochemistry.