Current Applied Materials - Volume 2, Issue 1, 2023

Background: Spontaneously polarized finely dispersed semiconductors can be sources of direct electric current, similar to thermoelectric converters. Their power is low due to the low electrical conductivity of the powders.

Objective: Theoretical description of the electromotive force of a spontaneously polarized homogeneous semiconductor film with ionized donor centers uniformly distributed over its two surfaces and free electrons in the volume. Establishment of technical characteristics and competitive advantages of using a film as a current source converts the received energy (heat or light) into the work of an electric field.

Methods: The theory of semiconductors and the laws of thermodynamics are used.

Results: Analytical expressions are obtained that describe the electronic processes in a metal-semiconductor-metal three-layer film and the technical characteristics of its use as a current source. Estimates are given on the example of a silicon film with arsenic-doped surfaces.

Conclusion: The universal principles for creating homogeneous solids of macroscopic dimensions are substantiated, with the efficiency of converting heat into the work of an electric field, which is significantly (by an order of magnitude) higher than the efficiency of materials used to create thermo-EMF sources. The heat absorbed by the metal-semiconductor-metal three-layer film serves as an energy source for a direct current in a closed circuit generated by this structure with an efficiency of 100%. The power of the current source 10 - 10⁵ W/m² depends on the received heat flow. A semiconductor film with a built-in electric field is an analogue of a p - n junction and does not have its drawbacks.

In diabetic wounds, reactive oxygen species (ROS) are developed in large quantities in a consistently hyperglycemic and excessive biogenic environment. Inflammatory factors are increased as a result of impaired hematopoiesis. Because, subsequent infections obstruct the healing process and as a result, most chronic wounds are not healed properly. The majority of chronic diabetic wounds are worsened during the inflammatory stage. Because of excessive ROS, it is still challenging for a timely closure of diabetic chronic wounds. Wound dressings with anti-inflammatory and ROS scavenging properties are preferable for the treatment of diabetic wounds. Hence, a strategic treatment is required which facilitates both targeting and myogenic potential. In recent decades, the production of macroporous hydrogels via three-dimensional (3D) printing has gained popularity as a cutting-edge technique for chronic wounds. Multiple hydrogel subtypes have been formulated for different states of healing of chronic wounds. The hydrogel used in 3D printing indicated better wound healing by enhancing the expression of adipose-derived stem cells (ASCs) activities in scaffolds due to the presence of an ordered macroporous structure. Regenerative medicine has undergone a paradigm shift as a result of the introduction of inventive medicines based on the use of living organisms. New treatments for skin wounds have been the subject of several studies, with bioactive peptides, nanoparticles, and hydrogels attracting a lot of attention due to their potential as therapeutics. For chronic wound healing, hydrogels create an angiogenesis microenvironment and avoid wound infections. Hence, the present review provides light on different superficial hydrogels along with their properties for chronic wound healing.

Hyperglycemia is a metabolic illness characterized by diabetes mellitus. Chronic hyperglycemia can lead to infection, production of more reactive oxygen species, chronic inflammation, and impaired angiogenesis, thus increasing the wound’s healing time. As the diabetic wound healing process is a more complex pathology, the demand to develop a topical application has emerged. This review focuses on the diabetic wound, wound healing, and the factors that influence diabetic wound healing. It also highlights the impact of combination delivery of antibiotics and antioxidants loaded with multifunctional hydrogel on diabetic wound healing. Due to the immense financial strain caused by this pathology, there is a need for other effective novel methods for wound healing. Therefore, multifunctional hydrogels, which are effective and have been used mainly as a carrier system for diabetic wound treatment, have been studied. Hence, the application of antibiotics and antioxidants loaded with multifunctional hydrogel in treating diabetic wounds is reviewed. Hydrogels present a significant theoretical reference for diabetic wound healing.

Aims: The formation of calcium phosphate apatite (hydroxyapatite, carbonate-containing hydroxyapatite, fluorapatite and carbonate-containing fluorapatite) in aqueous systems has been studied for over a century.

Background: However, in the region of low concentrations of liquid phases, the question of the nature, composition and region of existence of apatite compounds remains controversial.

Objective: The results of studying the phase equilibrium in the system CaO-P2O5-H2O at 298 K in the isotherm region from the invariant point of dicalcium phosphate and monocalcium phosphate monohydrate to the lowest concentrations of the liquid phase components are presented.

Methods: Chemical analysis, thermogravimetry, IR spectroscopy and optical microscopy were used for the analysis.

Results: Long-term monitoring of the establishment of equilibrium (up to 20 months) resulted in the determination of regions of stable solid phases of calcium orthophosphates, calcium-deficient apatites, hydroxyapatite, and apatite with (Ca/P)at >1.67. Two types of calcium-deficient apatite were identified that differ in the (Ca/P)at ratio: the first type is 1.33 < (Ca/P)at ≤ 1.5; the second one is 1.5 ≤ (Ca/P)at < 1.67.

Conclusion: The invariant points of calcium orthophosphates and compounds with the apatite structure were determined. The diagram was constructed using the Miller-Kenrick method based on obtained experimental data, which confirms the established regions and invariant points of stable equilibrium solid phases of the studied ternary system. The data obtained can be useful for understanding the processes of formation and change of compounds with apatite structure.