Nanoscale Apatite Biomaterials for Osteointegration

The thermal behavior of bone tissue has been investigated in order to assess how it is affected struc-turally by incineration. The need of the development of such technology is caused by big number of pa-tients with oncology and dystrophic bone tissue diseases which use the artificial bone tissue replacement. The samples like small plates that cut from local area of bone fragment, were exposed to annealing in tem-perature range 560-720 C and were characterized by XRD, SEM, EPMA, XPS and method of differential dissolution. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3547

Synthesis and characterization of hydroxyapatite-gelatine composite materials for orthopaedic application

The composite materials based on hydroxyapatite (HA) and gelatine (Gel) with addition of silver and zirconium oxide were obtained. The study investigates a combination of low powered ultrasonic irradiation and low concentration of gelatine in the co-precipitation synthesis. These composites have different weight ratios of organic/inorganic components and may be synthesized in two ways: simple mixing and co-precipitation. Both of which were compared. The estimation of porosity, in vivo testing, surface morphology and phase composition as well as the IR-analysis were provided. Hydroxyapatite was the main crystalline phase in obtained composites. While around powdered HA-Gel composite the connective tissue capsule is formed without bone tissue formation, HA-Gel-Ag porous composite implantation leads to formation of new bone tissue and activation of cell proliferation. Addition of silver ions into composite material allows decreasing inflammation on the first stage of implantation and has positive effect on bone tissue formation. Some of the obtained composite materials containing silver or ZrO2 are biocompatible. bio-resorbable and osteoconductive with high level of porosity (75e85%)

Heat capacity and phonon mean free path of wurtzite GaN

We report on lattice specific heat of bulk hexagonal GaN measured by the heat flow method in the temperature range 20-300 K and by the adiabatic method in the range 5-70 K. We fit the experimental data using two temperatures model. The best fit with the accuracy of 3 % was obtained for the temperature independent Debye's temperature $\theta_{\rm D}=365$ {\rm K} and Einstein's temperature $\theta_{\rm E}=880$ {\rm K}. We relate these temperatures to the function of density of states. Using our results for heat conduction coefficient, we established in temperature range 10-100 K the explicit dependence of the phonon mean free path on temperature $\it{l}_{\rm ph}\propto T^{-2}$. Above 100 K, there is the evidence of contribution of the Umklapp processes which limit phonon free path at high temepratures. For phonons with energy $k_{\rm B}\times 300$ {\rm K} the mean free path is of the order 100 {\rm nm}Comment: 5 pages, 4 figure

Modern application of the cost factor in the modern concept of enterprise management

Указано про особливості застосування концепції управління підприємством на основі оцінки його вартості. Звернуто увагу на наявність чинників, що формують вартість підприємства. Акцентовано на необхідності формування системи чинників вартості підприємства, що враховувала би основні чинники всіх методичних підходів до оцінки вартості підприємства.The article explains the features of the application of the concept of enterprise management based on the assessment of its value. The paper draws attention to the presence of factors that shape the value of the company. This work focuses on the necessity of formation of factors system of enterprise value, which takes into account the main factors of all methodological approaches to the valuation of the enterprise

The Study of the Influence of Static Magnetic Field on Brushite Crystallization in the Presence of Magnesium

The paper describes the influence of the imposition of static magnetic field on brushite crystallization. Two different configurations of the magnetic field were used. The flasks with the precipitates were placed near the different poles. It was shown that changing the magnetic field configuration and positioning the samples in proximity to north or south poles can greatly affect their crystallinity and texture with most of them having the preferred orientation along the b-axis according to the X-Ray diffraction data. The imposition of the magnetic field also influences the microstrain ratio decreasing it significantly. It was also verified [1] that the Mg substrate availability decreases the crystallinity of DCPD. The micrographs of the nanoparticles with the different magnifications were obtained by the transmission electron microscopy (TEM). The comparative analysis of the electron microscopy data correlates with the XRD data. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3546

Structural and crystal-chemical characteristics of the apatite deposits from human aortic walls

Thermal behavior of biological apatite is the object of several studies. Crystal size, carbonate content, phase composition, and other parameters change during annealing up to 900 °C in biological minerals with apatite structure. The way these parameters change reflects the specific properties of the initial bioapatite. This work presents data on thermal transformations of pathological bioapatite from the human cardiovascular system, namely aortic wall deposits. Some minor elements, foreign to calcium hydroxyapatite (e.g., Na and Mg), can be both incorporated in the apatite structure and localized in the surface layers of crystals, modifying functions of the mineral. A new approach was proposed to determine the predominant location of minor elements, such as Mg, Na, and K, in the mineral of pathological deposits. Mg and Na in pathological apatite can be in both structurally bound (substituting calcium in lattice) and labile (localized on the crystal surface) states, while K is not able to join the apatite structure in significant amount or be chemically bound to it. This approach, based on atomic spectrometry, can be used effectively in combination with a set of traditional techniques, such as like EDS, IRS, and XRD

Mechanical Properties of Natural Chitosan/Hydroxyapatite/Magnetite Nanocomposites for Tissue Engineering Applications

Chitosan (CS), hydroxyapatite (HA), and magnetite (Fe3O4) have been broadly employed for bone treatment applications. Having a hybrid biomaterial composed of the aforementioned constituents not only accumulates the useful characteristics of each component, but also provides outstanding composite properties. In the present research, mechanical properties of pure CS, CS/HA, CS/HA/magnetite, and CS/magnetite were evaluated by the measurements of bending strength, elastic modulus, compressive strength and hardness values. Moreover, the morphology of the bending fracture surfaces were characterized using a scanning electron microscope (SEM) and an image analyzer. Studies were also conducted to examine the biological response of the human Mesenchymal Stem Cells (hMSCs) on different composites. We conclude that, although all of these composites possess in-vitro biocompatibility, adding hydroxyapatite and magnetite to the chitosan matrix can noticeably enhance the mechanical properties of the pure chitosan

Research on distributed in-memory databases and cache implementation in SpringBoot application

Mezi cíle této bakalářské práce patří výzkum ukládání dat do mezipaměti v distribuovaných systémech a zkoumání platforem, které tuto funkci nabízejí. Následně je cílem implementovat aplikaci integrovanou s jednou z těchto platforem. Práce poskytuje srovnávací analýzu vybraných technologií, nastiňuje návrh architektury systému a prezentuje výsledky získané při testování implementované aplikace. Závěr navíc obsahuje návrhy na budoucí zlepšení.The objectives of this bachelor thesis include researching data caching in distributed systems and exploring platforms that offer this functionality. Afterwards, the aim is to implement an application integrated with one of these platforms. The thesis provides a comparative analysis of the chosen technologies, outlines the system architecture design, and presents the results obtained from testing the implemented application. Additionally, the conclusion includes suggestions for future improvements