Uniform and weak stability of Bresse system with one infinite memory in the shear angle displacements

In this paper, we consider a one-dimensional linear Bresse system in a bounded open interval with one infinite memory acting only on the shear angle equation. First, we establish the well posedness using the semigroup theory. Then, we prove two general (uniform and weak) decay estimates depending on the speeds of wave propagations and the arbitrary growth at infinity of the relaxation function.

Phenetics of the rock pigeon (Columba livia) plumage coloration in Orenburg

Birds differ from larger representatives, for example: mammals from the point of studying the class of birds. The following things are considered: data on hair dryers of coloring, patterns of feather cover, structure and coloring of the beak, flapping of the legs. Representatives of the class of birds, in particular synanthropic blue pigeons, have signs: features of trophic behavior and polymorphism. The paper describes distribution and main morphs of blue pigeons on the territory of Orenburg. The blue pigeon ( Columba livia ) is one of the most widespread ancient representatives, which is prone to migrations and has an extensive habitat around the world, and in urban conditions is one of the most frequently observed objects. Pigeons on the territory of Orenburg are represented by different morphs: white, black, black-stamped, brown and blue. On the territory of the Central District, during two periods, 1650 individuals of birds (1040 in spring, 610 in autumn) of different color morphs were identified, with a large predominance of black-stamped and brown. During the spring period the maximum number of birds and morphemes was high and during the autumn period the population decreased in number, as well as the ratio of the number of color morphemes. The observations were carried out in the Central District of Orenburg on three streets: March 8th, Tereshkova, Pobedy Avenue. 35 morphemes were identified in the Central District: 21 in spring and 14 in autumn. Spring morphemes in groupings, as well as their increase, were explained by combinative variability (that is due to increased reproduction in the spring period) and manifestation of recessive traits in the phenotypes of plumage coloring. Autumn morphemes were few in number; as a result, the loss is explained by a weak stability of certain color morphemes to environmental factors.

Stereocomplex Polylactide for Drug Delivery and Biomedical Applications: A Review

Polylactide (PLA) is among the most common biodegradable polymers, with applications in various fields, such as renewable and biomedical industries. PLA features poly(D-lactic acid) (PDLA) and poly(L-lactic acid) (PLLA) enantiomers, which form stereocomplex crystals through racemic blending. PLA emerged as a promising material owing to its sustainable, eco-friendly, and fully biodegradable properties. Nevertheless, PLA still has a low applicability for drug delivery as a carrier and scaffold. Stereocomplex PLA (sc-PLA) exhibits substantially improved mechanical and physical strength compared to the homopolymer, overcoming these limitations. Recently, numerous studies have reported the use of sc-PLA as a drug carrier through encapsulation of various drugs, proteins, and secondary molecules by various processes including micelle formation, self-assembly, emulsion, and inkjet printing. However, concerns such as low loading capacity, weak stability of hydrophilic contents, and non-sustainable release behavior remain. This review focuses on various strategies to overcome the current challenges of sc-PLA in drug delivery systems and biomedical applications in three critical fields, namely anti-cancer therapy, tissue engineering, and anti-microbial activity. Furthermore, the excellent potential of sc-PLA as a next-generation polymeric material is discussed.

From Enzyme Stability to Enzymatic Bioelectrode Stabilization Processes

Bioelectrocatalysis using redox enzymes appears as a sustainable way for biosensing, electricity production, or biosynthesis of fine products. Despite advances in the knowledge of parameters that drive the efficiency of enzymatic electrocatalysis, the weak stability of bioelectrodes prevents large scale development of bioelectrocatalysis. In this review, starting from the understanding of the parameters that drive protein instability, we will discuss the main strategies available to improve all enzyme stability, including use of chemicals, protein engineering and immobilization. Considering in a second step the additional requirements for use of redox enzymes, we will evaluate how far these general strategies can be applied to bioelectrocatalysis.

Preparation and Application of Polyurethane Coating Material Based on Epoxy Cyclohexane Protective for Paper

Paper is important to most historical and cultural relics, however, these paper heritages are facing a crisis of disappearance, damage and aging. For increasing the paper strength, delaying the paper aging, and improving the weak stability and permeability of former resins used for paper, another material is necessary to be produced on preservation and protection of the paper items. The synthesis of epoxy cyclohexane polyetherpolyol was as follows: Epoxy cyclohexane was as the starting material, ethylene glycol was as the initiator, boron trifluoride ether was as catalyst, and dichloromethane was as the solvent. The synthesized homopolyether was characterized by infrared (IR) spectroscopy and proton nuclear magnetic resonance (1HNMR) spectroscopy to determine the structure. Then the epoxy cyclohexane homopolyether reacted with the hexamethylene diisocyanate (HDI) trimer, and the polyurethane was obtained. With the tests of the physical and chemical properties of paper samples, it showed that the paper processed with 10% polyurethane liquid had excellent performance, the increase in the tensile strength was from 1105 to 2317 N/m, and the increase in the folding endurance was from 20 to 504 times. What’s more, the paper processed with 10% polyurethane liquid had good brightness and gloss. The results of the paper samples for the test have shown that the synthesized material simultaneously has the advantages of epoxy cyclohexane homopolyether and polyurethane, possessing excellent performance in paper reinforcement. Thus, the synthesized polyurethane material has broad application prospect in paper protection field.

Self-supporting 3D hierarchically porous CuNi-S cathodes with dual-phase structure for rechargeable Al battery

Metal-based materials are considered as advanced cathodes to develop high-energy-density aluminum batteries. Powdery metal active materials are usually synthetized and loaded on current collector. Weak stability and low loading mass...

Ultrasonication-Prepared Copper-Doped Cesium Halide Nanocrystals with Bright and Stable Emission

All-inorganic cesium lead halide perovskite nanocrystals (NCs) are quite promising materials for emission-based applications. However, the intrinsic toxicity of lead as well as the weak stability remains to be resolved....