Pathologic findings on ruminant enteric clostridial diseases reveal specificities and differences among iota and iota-like toxins

The iota toxin (ITX) is a binary enterotoxin produced as a protoxin by Clostridium perfringens (C. perfringens) type E that is activated by proteolytic enzymes in the small intestine of infected animals. By depolymerization of the actin filaments, ITX causes cytoskeleton disorganization of cells promoting the increase of the cell permeability. Here, we conducted this review aiming to advance the understanding of enteric clostridial diseases caused by C. perfringens toxins and the specificity of ITX in the intestinal mucosa lesions. ITX consists of an enzymatic component (Ia) and a binding component (Ib). We screened the recently published histological findings of the ITX effects and its relationship with intestinal enteric diseases. Histologically, hemorrhagic necrosis and multifocal hemorrhage have been observed in the jejunum-ileum mucosa, the small intestine, and the abomasum. Although the diagnosis is still based on the presence of toxins in the intestinal contents and the clinical and/or histological history, it is important to develop novel enterotoxemic indicators capable of establishing precise methods for differentiate the actions of ITX and other toxins involved in the infectious process of C. perfringens type E.

Clostridioides difficile binary toxin binding component (CDTb) increases virulence in a hamster model

Clostridioides difficile is the leading cause of hospital-acquired gastrointestinal infection, in part due to the existence of binary toxin (CDT)-expressing hypervirulent strains. We have previously shown that CDT interacts with the TLR2/6 heterodimer to induce inflammation, and in this study we further explore this interaction as well as the contribution of the separate components of CDT, CDTa and CDTb. We found that the binding component, CDTb, is capable of inducing inflammation. Additionally, complementation of a CDT-deficient C. difficile strain with CDTb alone restored virulence in a hamster model of C. difficile infection. Overall, this study demonstrates that the binding component of C. difficile binary toxin contributes to virulence during infection.

Efficiency of mineral additives to binding component for making hardening mixtures at underground operations

For effective operation of mining enterprises, including mines of ferrous metallurgy, supply of quality binding components is necessary to make hardening mixtures for packing of goave, aroused at underground development of hard mineral deposits. Results of the study of compositions based on ash-cement, nepheline, belit-aluminates and lime binding component made of mining and metallurgical production wastes presented. Application of vibro-, mechanical- and electrochemical activation methods to obtain filling mixtures from local low-quality raw materials, as well as activation of binding components were analyzed. A model to evaluate efficiency of binding additives presented. It was shown that decrease of cement consumption by addition of binding components of mineral origin requires perfection of mining processes, first of all, grinding and activation. It was proved, that additions of electric filters ash, nephelines, belit-aluminates and lime, obtained by utilization of current and old tailings to the basic binding component – portland cement – makes it possible to obtain hardening filling mixtures, having high enough strength to apply them at goave packing. Application of the study results makes it perspective for depressed mining and related enterprises to survive under conditions of the forming market.

Use Of Olivine For The Production Of MgO-SiO2 Binders

The potential for using MgO and SiO2, recovered from olivine, was investigated for use as a cementitious binder system. The MgO to SiO2 proportion for the binder was fixed at 1:1. The nature of the hydration products were characterized using a variety of techniques including isothermal calorimetry, XRD, FTIR, and SEM. The primary binding component of the paste was determined to be magnesium silicate hydrate (M-S-H). The recovered silica exhibited faster reactivity compared to commercially available silica fume. Compressive strengths in excess of 20 MPa were obtained using the materials recovered from olivine.

Bilin-dependent regulation of chlorophyll biosynthesis by GUN4

Biosyntheses of chlorophyll and heme in oxygenic phototrophs share a common trunk pathway that diverges with insertion of magnesium or iron into the last common intermediate, protoporphyrin IX. Since both tetrapyrroles are pro-oxidants, it is essential that their metabolism is tightly regulated. Here, we establish that heme-derived linear tetrapyrroles (bilins) function to stimulate the enzymatic activity of magnesium chelatase (MgCh) via their interaction with GENOMES UNCOUPLED 4 (GUN4) in the model green alga Chlamydomonas reinhardtii. A key tetrapyrrole-binding component of MgCh found in all oxygenic photosynthetic species, CrGUN4, also stabilizes the bilin-dependent accumulation of protoporphyrin IX-binding CrCHLH1 subunit of MgCh in light-grown C. reinhardtii cells by preventing its photooxidative inactivation. Exogenous application of biliverdin IXα reverses the loss of CrCHLH1 in the bilin-deficient heme oxygenase (hmox1) mutant, but not in the gun4 mutant. We propose that these dual regulatory roles of GUN4:bilin complexes are responsible for the retention of bilin biosynthesis in all photosynthetic eukaryotes, which sustains chlorophyll biosynthesis in an illuminated oxic environment.

Management of hardening mixtures properties when stowing mining sites of ore deposits

Underground mining is characterized by the weakening of the bearing rock mass strata competence and the accumulation of mineral waste. The full use of subsurface resources is ensured by the use of technologies with filling voids by hardening mixtures, which requires high-quality raw materials to obtain the required strength. The deficit of the binding component can be filled with the use of granulated slags of blast-furnace process, mill tailings, ash-slags and other wastes. Most often, voids are laid by mixtures with a combination of cement and a binding component. Mixtures with ash-slag additives to cement in an equivalent amount are not inferior to the strength of the mixture only with cement, especially when grinding ash-slag. The properties of stowing rock masses when using composite binding components and inert fillers are controlled by mechanical, chemical, physical and energy effects at the stages of preparation and transportation of hardening mixtures. To obtain the active fraction of cement substitutes, disintegrators are used that apply the inertia forces of materials at a high speed of rotation with an increase in high activity indicators and lower energy costs. The components of hardening mixtures can be the majority of waste from mining and related industries, which is determined experimentally in specific conditions.

Application of 3-D Drucker–Prager Material Model to Determine Optimal Operating Parameters of Centrifugal Regeneration Device

The process of metal casting indisposable sand molds is associated with the generation of large amounts of waste, mainly used molding and core sands, from which the molds and cores reproducing the external and internal shapes of the castings were made. It is estimated that about 600 kg of waste can come from the production of 1 ton of casting. The main component of the waste is quartz matrix, which after undergoing appropriate reclamation treatments can be recovered and reused in the production process. This article presents the theoretical foundations regarding the existing methods of quartz matrix recovery and an experimentally justified model of the regeneration process occurring in one of the varieties used in the practice of mechanical regenerators. The goal is to improve the quality of regenerated molding sand by means of liberating the sand grain’s surface from the layer of the used binding component. The elastic-plastic material model characterized by the Drucker–Prager yield criterion was used to describe the deformation of the sand layer during treatment performed in a centrifugal regenerator. Conclusions based on the results of numerical calculations, obtained with the use of the software adopting the material point method, enable us to find out how to control the device in a way that ensures a permanent reclamation effect which is independent of the working components that wear out over time.