Ag‐Loaded WO3 Ceramic Nanomaterials: Characterization and Moisture Sensing Studies

Pellet samples of 0–4% weight Ag‐loaded WO₃ prepared through soft chemical route were sintered at 700°C and exposed to humidity. Resistance of the pellets decreased with increase in relative humidity. Sensitivity increased with increase in the % loading of Ag. Four percent Ag‐loaded WO₃ showed maximum sensitivity of 2.38 MΩ/% RH in 20–90% relative humidity range. This sensing element manifests highest crystallinity as well as maximum void concentration. Hysteresis and repeatability for this sensing element after 6 months are within ±2%. A polynomial fit of the humidification data revealed a strong correlation between resistance and relative humidity.     

Rule-driven processing of tree-structured data using pointed trees

This paper puts forward a data model based on pointed unranked trees labelled with arbitrary strings. An abstract transformation machine for this data model is presented that combines rule-driven processing with a very simple query mechanism. This machine is shown to be able to express any computable tree transformation. This suggests that the rule-driven processing principle is a powerful tool even when it is used in conjunction with a simple and weak query model. An implementation of this machine enhanced with regular expression-based query mechanism is discussed.     

Effect of Si(111) Surface Modification by Ga Focused Ion Beam at 30 kV on GaAs Nanowire Growth

This paper presents the results of experimental studies of the effect of Si(111) surface modification by Ga-focused ion beam (FIB) at 30 kV accelerating voltage on the features of the epitaxial GaAs nanowire (NW) growth processes. We experimentally established the regularities of the Ga ions’ dose effect during surface modification on the structural characteristics of GaAs NW arrays. Depending on the Ga ion dose value, there is one of three modes on the surface for subsequent GaAs NW growth. At low doses, the NW growth is almost completely suppressed. The growth mode of high-density (up to 6.56 µm⁻²) GaAs NW arrays with a maximum fraction (up to 70%) of nanowires normally oriented to the substrate is realized in the medium ion doses range. A continuous polycrystalline base with a dense array of misoriented short (up to 0.9 µm) and thin (up to 27 nm) GaAs NWs is formed at high doses. We assume that the key role is played by the interaction of the implanted Ga ions with the surface at various process stages and its influence on the surface structure in the modification region and on GaAs NW growth conditions.     

Fragment-Based Drug Discovery against Mycobacteria: The Success and Challenges

The emergence of drug-resistant mycobacteria, including Mycobacterium tuberculosis (Mtb) and non-tuberculous mycobacteria (NTM), poses an increasing global threat that urgently demands the development of new potent anti-mycobacterial drugs. One of the approaches toward the identification of new drugs is fragment-based drug discovery (FBDD), which is the most ingenious among other drug discovery models, such as structure-based drug design (SBDD) and high-throughput screening. Specialized techniques, such as X-ray crystallography, nuclear magnetic resonance spectroscopy, and many others, are part of the drug discovery approach to combat the Mtb and NTM global menaces. Moreover, the primary drawbacks of traditional methods, such as the limited measurement of biomolecular toxicity and uncertain bioavailability evaluation, are successfully overcome by the FBDD approach. The current review focuses on the recognition of fragment-based drug discovery as a popular approach using virtual, computational, and biophysical methods to identify potent fragment molecules. FBDD focuses on designing optimal inhibitors against potential therapeutic targets of NTM and Mtb (PurC, ArgB, MmpL3, and TrmD). Additionally, we have elaborated on the challenges associated with the FBDD approach in the identification and development of novel compounds. Insights into the applications and overcoming the challenges of FBDD approaches will aid in the identification of potential therapeutic compounds to treat drug-sensitive and drug-resistant NTMs and Mtb infections.     

Targeting of the Mitochondrial TET1 Protein by Pyrrolo[3,2-b]pyrrole Chelators

Targeting of epigenetic mechanisms, such as the hydroxymethylation of DNA, has been intensively studied, with respect to the treatment of many serious pathologies, including oncological disorders. Recent studies demonstrated that promising therapeutic strategies could potentially be based on the inhibition of the TET1 protein (ten-eleven translocation methylcytosine dioxygenase 1) by specific iron chelators. Therefore, in the present work, we prepared a series of pyrrolopyrrole derivatives with hydrazide (1) or hydrazone (2–6) iron-binding groups. As a result, we determined that the basic pyrrolo[3,2-b]pyrrole derivative 1 was a strong inhibitor of the TET1 protein (IC₅₀ = 1.33 μM), supported by microscale thermophoresis and molecular docking. Pyrrolo[3,2-b]pyrroles 2–6, bearing substituted 2-hydroxybenzylidene moieties, displayed no significant inhibitory activity. In addition, in vitro studies demonstrated that derivative 1 exhibits potent anticancer activity and an exclusive mitochondrial localization, confirmed by Pearson’s correlation coefficient of 0.92.     

The Structural Interactions of Molecular and Fibrillar Collagen Type I with Fibronectin and Its Role in the Regulation of Mesenchymal Stem Cell Morphology and Functional Activity

The observed differences in the structure of native tissue and tissue formed in vitro cause the loss of functional activity of cells cultured in vitro. The lack of fundamental knowledge about the protein mechanism interactions limits the ability to effectively create in vitro native tissue. Collagen is able to spontaneously assemble into fibrils in vitro, but in vivo, other proteins, for example fibronectin, have a noticeable effect on this process. The molecular or fibrillar structure of collagen plays an equally important role. Therefore, we studied the interaction of the molecular and fibrillar structure of collagen with fibronectin. Atomic force and transmission electron microscopy showed that the presence of fibronectin does not affect the native structure and diameter of collagen fibrils. Confocal microscopy demonstrated that the collagen structure affects the cell morphology. Cells are better spread on molecular collagen compared with cells cultured on fibrillar collagen. Fibronectin promotes the formation of a large number of focal contacts, while in combination with collagen of both forms, its effect is leveled. Thus, understanding the mechanisms of the relationship between the protein structure and composition will effectively manage the creation in vitro of a new tissue with native properties.