Advanced analysis in epidemiological modeling: Detection of wave

Some mathematical concepts have been used in the last decades to predict the behavior of spread of infectious diseases. Among them, the reproductive number concept has been used in several published papers for study the stability of the spread. Some conditions were suggested to predict there would be either stability or instability. An analysis was also suggested to determine conditions under which infectious classes will increase or die out. Some authors pointed out limitations of the reproductive number, as they presented its inability to fairly help understand the spread patterns. The concept of strength number and analysis of second derivatives of the mathematical models were suggested as additional tools to help detect waves. In this paper, we aim at applying these additional analyses in a simple model to predict the future. Keywords: Strength number, second derivative analysis, waves, piecewise modeling.

Insight into the Evolution of the Cellulose Microstructure Through the Enzyme Pretreatment Method

In this work, the changes of properties and microstructure of cellulose (bleached hardwood kraft pulp (BHKP)) subjected to different enzyme pretreatment times (0–10 h) were explored for further fibrillation. The various properties of the pretreated cellulose gradually decrease with the elapse of time relative to the pristine material, such as yield, water retention value, aspect ratio and degree of polymerization, etc. Enzyme pretreatment can promote the peeling of fibrils and loosen the amorphous areas of cellulose identified by Scanning Electron Microscope (SEM) and X-ray diffraction (XRD). A thorough investigation of the relation between pretreatment and evolution of inter-/intra-molecular H-bonds in cellulose was conducted including content and cleave sequence of H-bonds by Fourier transform infrared spectroscopy (FTIR), second derivative analysis and generalized two-dimensional correlation spectroscopy (2DCOS). The intermolecular H-bonds with the most significant decrease in content was cleaved first relative to the intramolecular H-bonds. These discoveries provide theoretical support to more effective pretreatment method for commercial production of fibrils from cellulosic fibers.

Text Derivative Description of Political Discourse (based on the example of Kazakhstani Internet comments)

The proposed article is devoted to the study of political Internet comments published on Kazakhstani sites. The text of a political article has a potential of derivational functioning, which is realized in the text of an online commentary and is objectified in it under influence of variable strategies and tactics. The purpose of the study is to determine the textual parameters of the text generation of Kazakhstani political Internet comments in the linguistic-personalological aspect. In the course of linguistic analysis, the following methods were used: linguistic description, derivatological analysis technique, sampling method. The study is based on a model of the text-derivatological analysis of derivative texts, which are considered in the formal, substantial and functional plans. As a text-derivative analysis’ result of political Internet comments, the text parameters of the text generation were identified. The result of text-derivatological and linguoculturological research showed that Kazakhstani Internet comments are dominated by a text strategy

Derivative Analysis of Value Added to Stock Returns at Jakarta Islamic Index

<p>This study aims to examine the effect of value added derivative such as economic value added (EVA), market value added (MVA) and refined economic value added (REVA) on stock return with stock price as an intervening variable. The object of this study are all Islamic stocks listed in the Jakarta Islamic Index (JII) in the period 2014-2019. This study using purposive sampling method and obtained by 11 companies. Data processing using panel regression with common, fixed and random modelling approach. The results show that economic value added (EVA) has no effect either on stock prices or stock returns, market value added (MVA) affects the stock price and stock return, while refined economic value added (REVA) has no effect on both. Then, stock prices are only able to mediate the effect of market value added (MVA) on stock return.</p>

The Influence of Ag on the Microstructure and Properties of Cu-Ni-Si Alloys

The influence of the mass concentration of Ag on properties of Cu-Ni alloys is investigated. The effect of silver addition on the structure and properties of Cu-2Ni-1Si alloys is determined. The scientific aim of this research is to determine how the addition of silver affects the mechanisms of strengthening silver-modified supersaturated, deformed, and aged Cu-2Ni-1Si alloys. The applied thermo-derivative analysis has allowed us to determine a range of the temperature values for the beginning and the end of crystallization, the phases and eutectics, and the effects of the modification on the solid fraction of the solidified alloy. In addition to the crystallization kinetics, the microstructure morphology, mechanical properties under real operating conditions, and the electrical conductivity have also been investigated. Moreover, the conducted research includes the impact of heat treatment and plastic deformation on the alloy structure and considers the type, share, and distribution of the intermetallic phases and structural stresses caused by coherent phases, as well as the effect of dislocations in the reinforcing phases during aging. Electron microscopy (SEM), micro-area analysis (EDS), optical microscopy, hardness measurements, and conductivity of the tested alloys are utilized to comment on these properties.

Study of graphite-like materials obtained from coal-tar pitch

In the research, the study of precursors of graphite-like materials obtained from medium-temperature coal tar pitch was carried out on the individual components of coal tar pitch by separating the multicomponent composition of the pitch into separate fractions. Such approach, to study the physicochemical characteristics of the individual components of coal tar pitch, contributes to both the determination of the contribution of individual pitch components to the process of its structuring during carbonization and the development of new environmentally friendly methods for the synthesis of functional materials for various applications. The β-fraction was precipitated with n-hexane from toluene extract of coal tar pitch. γ-fraction was isolated from n-hexane by solvent evaporation. α2-fraction was isolated from the residue, insoluble in toluene, by quinoline extraction. The composition and structure of the isolated individual fractions of coal tar pitch were studied by physicochemical methods of analysis. The shape and morphology were investigated by electron microscopy. To study the composition and structure, the methods of elemental analysis, infrared spectroscopy, electron-paramagnetic resonance, XRD-analysis, and thermoanalysis were used in combination with methods of derivative analysis, chromatography, and mass spectrometry. The authors of the work propose new approaches to the use of individual fractions of coal tar pitch in order to obtain new graphite-like materials on their basis.