Influence Of Micro Research Articles

Analysis of the Return and Risk of Investment in Insurance Companies Listed on the Indonesia Stock Exchange

The return and risk of stock investment have a high level of volatility because it depends on fundamental and technical conditions and the influence of micro and macro variables. This study aims to determine the risk and return on investment in insurance companies and analyze the effect of macroeconomic variables on the level of risk and return on investment in insurance companies. The sampling technique used was purposive sampling. Data analysis shows that for three years, Asuransi Jasa Tania Tbk has the highest level of conclusion, which is 22.3%, and Asuransi Harta Aman Pratama Tbk. has the lowest rate of -3.3%. For three years, the value of Gross Domestic Product has increased successively so that this will cause a stock return that is proportional to the level of risk that will be faced. Changes in the inflation rate up and down for three consecutive years have a different effect every year where when the inflation rate decreases, the rate of return on investment will be high. In addition, the interest rate decreased from 4.75% in 2016 to 4.25% in 2017. Then it increased to 6.00% in 2018. The Rupiah exchange rate against the dollar is getting weaker, indicating an increase in the exchange rate. Every year from 2016 to 2018. When the rupiah exchange rate weakens, people will choose to invest in foreign currencies because the value of these foreign currencies can determine the size of the risk of a business.

ECOLOGY OF ARCHITECTURAL (NATURAL-ANTHROPOGENIC) ENVIRONMENT UNDER ABIOTIC ENVIRONMENTAL TRANSFORMATIONS

Formulation of the problem. Ecology is understood as a science that studies the environment and its relationship with human activity, as well as a means of reducing anthropogenic pressure. Architecture ecology, as a branch of architectural science, needs to expand the methods of studying the regime of environmental factors, as well as trends in their regional change. The purpose of the article is to study the directions of improving methods for determining the characteristics of an architectural space, which can provide a basis for determining environmental performance indicators. When designing local zones of recreational gullies, parks, forests, one should take into account the environment of the transforming and transgressive influence of micro-, meso-, and macrobiogeocenosis systems. Results. Based on the study of experience, it is proposed to systematize the environment from the point of view of ecology. In particular, the following types of architectural and ecological space are distinguished: according to the composition of the material basis − natural, quasi-natural, artificial, combined; by the state of ecological balance − ordered, unstable, violated; after interaction with others − open, half-open, closed, isolated, hermetic; in accordance with the structure − central, peripheral, borderline, linking; from the point of view of energy-informational impact on a person − Biopositive (beneficial), neutral, extreme and pathogenic. Scientific novelty and practical significance. The research carried out by the author has somewhat changed the approach to systematizing the environment from the point of view of ecology. The types of architectural and ecological space are theoretically substantiated. Practical significance dedicated to the concepts of architectural space and issues of its topology, morphology and semiotics, as well as in works on the study of the composition of architectural space, highlight certain aspects of architectural ecology.

Nanomodification of mineral binders

In the result of researches performed on the directed regulation of properties of gypsum binders, it was determined that the specific surface of various anisotropic surfaces regulates the shape of crystals as well as kinetics of their formation and growth. It has been established that the process of hydration and formation of gypsum binders can be regulated through the size of the specific surface, parameters of nanoadditives as well as through the change of concentration in solution. The influence of micro - and nanoadditives on the change of the system surface energy, as well as on introduction of plasticizer and change of time solution is in the supersaturated state (which increases the number of nuclear centers of crystallization) has been established experimentally and theoretically proved.

Shaping a Circular Economy in the Digital TV Industry: Focusing on Ecopreneurship through the Lens of Dynamic Capability

In this study, we investigate how companies can contribute to achieving a circular economy (CE) in the electronics industry viewed through the lens of dynamic capability. In particular, we examine how companies can contribute through idiosyncratic ecopreneurship according to dynamic capabilities with three points: the dynamic capabilities of established companies, the formation of ecopreneurship according to idiosyncratic dynamic capabilities, and the shaping of a CE through the interplay of ecopreneurship and dynamic capabilities of established companies. We conducted a case study of five leading TV manufacturers (Samsung, LG, Sony, Hisense, and TCL) to verify our conceptual framework, which we derived from a literature review. The case study shows that a company’s contribution to the CE and ecopreneurship type largely depend on a combination of dynamic capabilities and business strategies. Based on the case study results, we derived managerial implications with three points: the approach of leading companies to CE with consideration of business strategies, leveraging ecopreneurship to gain competitiveness in the market, and the influence of micro- and meso-level dynamic capabilities on a company’s contribution to CE.

Facile Electrochemical Method for the Fabrication of Stable Corrosion-Resistant Superhydrophobic Surfaces on Zr-Based Bulk Metallic Glasses.

Both surface microstructure and low surface energy modification play a vital role in the preparation of superhydrophobic surfaces. In this study, a safe and simple electrochemical method was developed to fabricate superhydrophobic surfaces of Zr-based metallic glasses with high corrosion resistance. First, micro–nano composite structures were generated on the surface of Zr-based metallic glasses by electrochemical etching in NaCl solution. Next, stearic acid was used to decrease surface energy. The effects of electrochemical etching time on surface morphology and wettability were also investigated through scanning electron microscopy and contact angle measurements. Furthermore, the influence of micro–nano composite structures and roughness on the wettability of Zr-based metallic glasses was analysed on the basis of the Cassie–Baxter model. The water contact angle of the surface was 154.3° ± 2.2°, and the sliding angle was <5°, indicating good superhydrophobicity. Moreover, the potentiodynamic polarisation test and electrochemical impedance spectroscopy suggested excellent corrosion resistance performance, and the inhibition efficiency of the superhydrophobic surface reached 99.6%. Finally, the prepared superhydrophobic surface revealed excellent temperature-resistant and self-cleaning properties.

Establishing patterns in the influence of micro- and nano-dispersed mineral additives on the water resistance of construction gypsum

This paper reports a study into the effect of mineral fillers such as ground granulated blast furnace slag, microsilica, and nano dispersed alumina on the structure formation and water resistance of gypsum. The theoretical models of gypsum stone structure with mineral fillers have been built and described, taking into consideration the sign of the surface charge of gypsum crystals and filler particles. In accordance with the developed models, the fillers enable the formation of a dense structure of gypsum stone as a compositional material with a large number of electro-heterogeneous contacts. With this structure, the gypsum dihydrate crystals are maximally protected from contact with water and dissolution. The electron microscopic study of the gypsum stone with mineral fillers has been carried out, which has confirmed that the rational ratio of gypsum to slag ensures the densest structure of the stone. The dependences of the strength of gypsum stone in the dry and water-saturated condition and a water resistance factor (softening) on the content of slag, micro-and nano dispersed filler, a water-hardened ratio, have been experimentally established. The introduction of a rational amount of microfiller with a negative surface charge (microsilica) has increased the water resistance ratio by 0.2‒0.4 amounting to a value of 1. The introduction of a rational amount of micro-filler with a positive surface charge (nano dispersed alumina) has improved the water resistance ratio by 0.8 amounting to a value of 0.9. The established mechanism that forms the gypsum stone structure with fillers would make it possible to develop the compositions for a mineral binder based on gypsum, which could be used under wet operational conditions

Improved removal of Congo Red from wastewater by low-rank coal using micro and nanobubbles

The influences of micro and nanobubbles (MNBs) on the adsorption of Congo Red (CR) on low-rank coal (LRC) were investigated. The size of microbubbles and nanobubbles diameters ranged from 2 to 600 μm and 50–200 nm, respectively. MNBs simultaneously increased adsorption capacity and rate of CR on LRC; the maximum adsorption rates achieved with the use of MNBs were 2 times of that without MNBs for both Wanli and Mengdong coal. Without MNBs, it took 25 min for Wanli coal to achieve the same residual CR concentration that Wanli with MNBs achieved in 1 min. The MNBs mainly reduced the CR concentration through the generation of OH radicals and improvement of its adsorption on LRC. MNBs were easy to attached to LRC particles, so they could act as “porter” to carry CR to LRC. The high concentration of CR-carrying MNBs increased CR/LRC contact probability to accelerate the adsorption of CR. The mechanism by which MNBs assisted adsorption provides a new method of removing organic pollutants in less time and with lower cost, which holds great potential in a wide range of applications.

The influence of the size of corundum particles on the properties of chemically resistant porcelain enamels

Porcelain enamels are silica-based inorganic coatings, which are successfully applied to different kind of metallic substrates in applications where high chemical resistance and corrosion protection are needed. The main weakness of enamel coatings is represented by the glassy and brittle nature of the matrix: therefore, it is necessary to find some solutions to address this issue effectively and improve their resistance to abrasion. Some recent papers about the production of composite enamels with Al2O3 particles showed that a high concentration of corundum particles (10–20 wt%) could improve the abrasion resistance of these coatings. This work is focused on studying the influence of micro and macro sized corundum particles on the abrasion and chemical resistance of composite enamel coatings. The Al2O3 particles are added in 20 wt % concentration and the firing treatment is optimized for every sample type. The coatings topography and morphology are mainly characterized by scanning electron microscopy measurements and Energy Dispersive X-ray (EDX) microanalysis. The abrasion resistance of the coatings is evaluated by P.E.I. abrasion test. Mass loss and roughness measurements are used to assess the coatings surface properties during the mechanical damage; in addition, Electrochemical Impedance Spectroscopy (EIS) measurements and electron microscopy observations are carried out after 5000 P E.I. abrasion cycles to evaluate the decrease of the coatings protection properties due to mechanical damage. Finally, the coatings chemical resistance is evaluated by exposure to an aggressive fog with the presence of SO2 (Kesternich test), simulating an industrial environment. The addition of macro sized alumina particles leads to an improvement of the coating abrasion resistance, without a loss in the protection properties. Differently, the addition of micro sized alumina particles produces an increase of the coating surface roughness and results to have detrimental effects on the behaviour of the coating in aggressive environments.

Support for Marginalized Children: Influences of Micro and Meso Contexts on Socially Just Principal Practices

This qualitative case study research examines the perceptions of three U.S. principals as they work for social justice in the school level meso context as enacted through the lens of their micro contextual values and beliefs. Through interviews with three rural high school principals, we look to the influence of context on decision making through a study of the principals’ articulations of the role of context in supporting or hindering their work for marginalized children. Findings from this study point to the culture of the community in which the school was situated and the challenges sometimes associated with the community as the most mentioned meso factor that guided the principals’ practice. The micro context of the leader’s personal story was a testament to what they valued and how they enacted these values as a leader for social justice. The study concludes with a model which reconceptualizes the macro, meso, and micro relationships not as a directional relationship that indicates the influence of one context onto another, but as a structural bond suggesting interdependency.

Thermal properties of polyethylene compositions with micro-and nanocellulose

The effect of micro- and nanocellulose addition on the thermal properties of polyethylene compositions has been studied by means of thermogravimetric analysis and pyrolysis-gas chromatography-mass spectrometry. The main temperature characteristics of the thermo- and thermo-oxidative degradation of the compositions are determined. The influence of micro- and nanocellulose additives on change of the distribution of hydrocarbon pyrolysis products of composite materials was established.

The influence of micro- and nanodots lubricating and cooling technological means (LCTM) on the process of blade cutting of materials

Improving the efficiency of cutting tools and the quality of the processed surfaces in the course of metal blade processing is largely determined by the intensity of adhesive interactions between the tribo-conjugated surfaces of the tool and processed materials. This is due to the high chemical activity of the juvenile surfaces formed in the process of chip separation in tribo-conjugated contact. As it is illustrated by theory and practice, one of the main mechanisms effecting on the amount of adhesion is the formation of separation lubricant films at the interface between the tool and the processed material by introducing external technological means into the contact zone (lubricating and cooling technological means – LCTM).

Algorithms for Numerical Solution to the Problem of Diffusion in Nanoporous Media

Introduction. Mathematical modeling of mass transfer in heterogeneous media of microporous structure and construction of solutions to the corresponding problems of mass transfer was considered by many authors [1–9, etc.]. In [6, 7] authors proposed a methodology for modeling mass transfer systems and parameter identification in nanoporous particle media (diffusion, adsorption, competitive diffusion of gases, filtration consolidation), which are described by non-classical boundary and initial-boundary value problems taking into account the mutual influence of micro- and macro-transfer flows, heteroporosity, the structure of microporous particles, multicomponent and other factors. In [8, 9] for a mathematical model of nonstationary diffusion of a single substance in a nanoporous medium described in [2] in the form of a multi-scale differential mathematical problem, the classical problems in the weak formulation were obtained. In this paper, algorithms for solving the above mathematical problems are constructed by using the finite element method. The results of the numerical solution of the test problem are presented. The results confirm the efficiency of the developed algorithms. The purpose is to solve a problem of nonstationary diffusion of single substance in nanoporous medium by constructing discretization algorithms using FEM quadratic basis functions. Results. Algorithms for the numerical solution of the problem of nonstationary diffusion of single substance in a nanoporous medium are proposed. Peculiarities of discretization of the region and construction of the matrix of masses, stiffness, and vector of right-hand sides when solving the problem by using FEM are described. The efficiency of the developed algorithms is confirmed by the results of solving a model example. Keywords: mathematical modeling, numerical methods, nonstationary diffusion, nanoporous medium, finite element method.

Influence of micro and nano carbon fillers on impact behavior of GFRP composite materials

Glass fiber-reinforced polymer (GFRP) composite with neat epoxy matrix and GFRP composite with epoxy-Micro carbon and epoxy-MWCNT composite matrix in were prepared. Micro and Nanofillers taken at 5,10,15 wt%(wt%) and 2,4,6 wt% respectively. The un-notched impact test is carried on each specimen as per ASTM D4812. The strength values are compared with neat epoxy matrix five layers of GFRP composite. The lack of a notch makes test method especially useful for reinforced materials where a notch may mask the effects of the notch. The impact response measured in terms of impact strength. Rest results showed that there is a significant impact of filler material on the strength. The size of particles is also showing a definite mark on the impact response. The 4 wt% Nano filler in Epoxy GFRP showed better results than all other samples. In micro fillers, 5 wt% of composition composite exhibited better strength. Overall, the research showed the potential to tailor composite properties to enhance impact performance by using different types, concentrations, and configurations of nano/microparticles.

Fabrication and Microstructure of Micro and Nano Silicon Carbide Reinforced Copper Metal Matrix Composites/Nanocomposites

This study investigates the influence of micro and nano silicon carbide on properties of copper matrix composites/nanocomposites containing up to 4 wt% of reinforcement concentration. It was observed that an increase of SiC (both micro and nano sized) content resulted in a higher hardness, compressive strength and better wear properties. However, nano SiC reinforced composite materials have better hardness, compressive strength and wear properties as compared with micro sized SiC reinforced composites. Grain refinement of composite/nanocomposite materials as compared with pure copper materials were observed from the metallurgical microscopic images. Further, scanning electron microscopic images revealed uniform dispersion/distribution of reinforcing materials in the copper matrix, and good bond formation between component materials. As the micro/nano sized SiC reinforcement in the copper matrix decreased the density of resultant composite/nanocomposite materials, therefore, nano sized SiC reinforcement will be helpful to fabricate light weight copper matrix nanocomposite materials for various industrial applications.

MiR-204 inhibits inflammation and cell apoptosis in retinopathy rats with diabetic retinopathy by regulating Bcl-2 and SIRT1 expressions.

To explore the influences of micro ribonucleic acid (miR)-204 on the rats with diabetic retinopathy by regulating the expressions of B-cell lymphoma 2 (Bcl-2) and sirtuin 1 (SIRT1). A total of 36 Sprague-Dawley rats were randomly assigned into normal group (n=12), model group (n=12), and miR-204 mimics group (n=12). No treatment was performed in the normal group, the diabetic retinopathy model was established in model group, and miR-204 mimics were administered for intervention after modeling in the inhibitor group. After 7 d, materials were sampled for detection. The expressions of Bcl-2 and SIRT1 were detected via immunohistochemistry, and their relative protein expression levels were determined via Western blotting (WB). Quantitative Polymerase Chain Reaction (qPCR) was performed to detect the expression of miR-204, and the content of inflammatory factors interleukin (IL)-6, IL-18, and tumor necrosis factor-α (TNF-α) was measured using enzyme-linked immunosorbent assay (ELISA). Finally, cell apoptosis was evaluated via terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL). Immunohistochemistry results showed that the positive expression levels of Bcl-2 and SIRT1 were substantially lower in the model and miR-204 mimics groups than those in the normal group (p<0.05), and their positive expression levels in miR-204 mimics group were notably higher than those in model group (p<0.05). According to Western blot (WB) results, the relative protein expression levels of Bcl-2 and SIRT1 markedly declined in the other two groups compared with those in the normal group (p<0.05), while miR-204 mimics group exhibited remarkably higher relative protein expression levels of Bcl-2 and SIRT1 than the model group (p<0.05). The results of qPCR revealed that the relative expression level of miR-204 was markedly lowered in model and miR-204 mimics groups compared with that in the normal group (p<0.05), and its relative expression level in miR-204 mimics group was remarkably higher than that in the model group. It was found through enzyme-linked immunosorbent assay (ELISA) that compared with normal group, the other two groups had substantially increased content of IL-6, IL-18, and TNF-α (p<0.05), and the content of IL-6, IL-18, and TNF-α in miR-204 mimics group was markedly lower than that in the model group (p<0.05). According to TUNEL results, the apoptosis rate of cells rose substantially in the other two groups compared with that in the normal group (p<0.05), while was notably lower in the miR-204 mimics group than that in the model group (p<0.05). MiR-204 up-regulates Bcl-2 and SIRT1 expressions to inhibit the inflammation and cell apoptosis in rats with diabetic retinopathy.

Total enthalpy-based lattice Boltzmann simulations of melting in paraffin/metal foam composite phase change materials

Phase change materials (PCM) have become a popular choice for building thermal management due to their low cost, chemical stability and high energy density. Though, their low thermal conductivity is a limiting factor in their use. To overcome this limitation, there has been considerable interest in the application of highly conductive substrates such as metal foams. These offer a potential to increase the thermal performance of PCM and to broaden their area of application. However, the influence of micro structured properties on melting is not completely understood and difficult to explore experimentally. In this study, a lattice Boltzmann method (LBM) based on the two relaxation time (TRT) collision scheme for the simulation of melting and conjugate heat transfer is proposed, validated and applied to melting in three-dimensional (3D) structures of composite PCM-metal foam latent heat storages. The model and its implementation is validated against the analytical transient solution of the Stefan problem, proving superlinear grid convergence and close agreement for a large range of lattice relaxation times and Stefan numbers. The interfacial diffusion is found to be effectively limited by leveraging a TRT collision scheme. Very close accordance to measurements and simulation results obtained with other methods is shown for the validation case of melting gallium including natural convection in 2D and 3D. Subsequently, the melting of paraffin in two complex metal foam geometries is simulated. The present simulations successfully describe the multi-domain heat transfer in 3D, where the thermal conductivity of the foam is more than 1000 times larger than that of the paraffin. The predicted progression of the melting front and the influence of the different foam’s specific surface area are in close agreement to earlier simulations.

A comparison of the influence of micro- and nano-silica on hydration kinetics of Portland cement under different temperatures

Exothermic characteristics of Portland cement incorporating 1%wt micro- and nano-silica were researched by measuring the heat releases at different testing conditions. The presence of nano-SiO2 reduces the induction period, and this effect changes with temperature. The rising temperature makes silica fume generate more significant influence on the induction period. The maximal heat release rate is influenced slightly at normal temperature and decreased to some extent at elevated temperatures through replacing 1%wt cement by micro- and nano-silica. The effects of nano-SiO2 and silica fume at 60 °C are almost completely consistent with each other within 7 h of hydration including induction state, acceleration state and deceleration state. Silica fume presents the property of nano-SiO2 at high temperatures, which can also be observed by analyzing their cementitious indexes. The reaction kinetics of cement with nano-SiO2 and silica fume was analyzed by the classical Krstulović-Dabić model. The analysis results indicate that nano-SiO2 and silica fume can improve the hydration degrees (α1 and α2) of the transformation from nucleation and crystal growth (NG) process to phase boundary reaction (I) process or I process to diffusion (D) process only at 60 °C. Nano-SiO2 can improve the phase boundary reaction at 50 °C and 60 °C judging by the difference between α1 and α2. The possible mechanism of nano-SiO2 and silica fume influencing the hydration kinetics was also proposed.

Micro and Nanoparticles of Metals and Metal Oxides and Physicochemical Properties of Highenergy Materials Based on Cyclic Nitroamines

The paper studies the influence of micro- and nanoparticles of metals and metal oxides on physicochemical properties of high-energy materials comprising cyclic nitroamine crystals. The micro- and nanoparticle encapsulation technique is developed for such cyclic nitroamines as 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and 2,4,6,8-tetranitro-2,4,6,8- tetraazaicyclooctane (octogen, HMX). Studied and analyzed are physicochemical properties of the novel high-energy materials comprising crystals of cyclic nitroamines. It is found that among the main parameters affecting the particle-size distribution in the crystals and the volume fraction of the metal inclusions, of critical importance is the stirring rate of the reaction mixture when distilling off the solvent. The low stirring rate leads to the formation of polycrystalline structures with the branched surface and multiple defects. Although the conditions of the CL-20 crystallization (solvent/precipitator ratio, temperature, a mixer type, distillation rate) are similar for different aluminum grades (ASD-6 and ALEXTM), the shape and size of the synthesized crystals strongly differ in both cases. The CL-20Alex crystal is characterized by the lower size (~100–150 μm), more tapered sides and greater number of the surface defects than crystals with other inclusions. This is probably because the effect from metallic particles acting as inoculating crystals.

Characterization of Aluminum Powders: III. Non‐Isothermal Oxidation and Combustion of Modern Aluminized Solid Propellants with Nanometals and Nanooxides

AbstractAluminum powders were comprehensively described as the prospective ingredients of the modern propellants. The paper also studied the influence of micro‐ and nanopowders of metals (μ‐Me and n‐Me) and metal oxides (μ‐MeO and n‐MeO) on the burning process of modern aluminized propellant with HMX, CL‐20, AP, and active binder. The following metal additives were used: Al, B, Zn, Ni, Co, and Mo. The effect of the following oxides CoO, V2O5, MnO2, and Fe2O3 was studied together with LiF. The combustion tests of modified propellant compositions were carried out in the Vielle bomb in a pressure range 2–10 MPa. n‐Me addition resulted in an increase in the burning rate by 10 % for n‐B, by 30–40 % for n‐Ni and n‐Mo in the studied pressure range. The introduction of n‐Cu caused a burning rate to increase fivefold. n‐Zn additive resulted in increasing of the propellant burning rate by 130 % and 260 % at 4 and 10 MPa, respectively. It was probably caused by the catalytic activity of those metals in the gaseous phase. The effect of complex additive was observed to be insignificant for additives with μ‐Co3O4, μ‐V2O5, μ‐Fe2O3 and n‐Fe2O3. The burning rate of propellant with n‐CuO additive value was higher by a factor of 4 in comparison with the basic formulation in the studied pressure range.

Heat transfer and convection of evaporating sessile droplets in transition from superhydrophilic to superhydrophobic structured wall: Optimization of functional properties

Abstract The free convection and heat transfer of evaporating water droplets on a textured wall have been studied. The analysis of the influence of micro- and macrotextures on the heat transfer coefficient has been performed. Structured surfaces were created by two different methods: mechanical surface treatment and laser exposure. The behavior of heat transfer on a structured wall was compared with that on a smooth surface. The wettability of the wall varied over a wide range of contact angles (the transition from a superhydrophilic to a superhydrophobic surface was considered). Simple relations have been obtained to estimate the separate influence of several key factors (the drop height, the surface area of the wetted spot of the drop, the convection velocity in the liquid and the temperature difference in the drop). The obtained data are important for designing heat exchangers with structured walls and for optimizing the functional properties.