Variations In Physical Properties Research Articles

Presence and production of Tuber aestivum in relation with the soil environment of a semi-natural experimental truffle orchard in Spoleto, Central Italy

Truffles produced by Tuber species (Ascomycota) represent an additional income in economically marginal areas, especially if cultivating mycorrhized seedlings in dedicated truffle orchards. However, despite the great progress made in cultivation, truffle production has not increased substantially. One of the reasons may be the lack of knowledge on soil as a key component of truffle species habitats. This is the case for Tuber aestivum, whose soil environment has been studied less than those of T. magnatum and T. melanosporum due to the lower economic value of its ascocarps. We did the present study in an experimental truffle orchard submitted to a light tillage before our investigation and characterized by the presence of different host tree species and soil variation in space. We assessed whether truffle production and T. aestivum mycelial DNA in soil varied depending on symbiont tree species, soil type or both by comparing sub-areas characterized by the presence/absence of: i) two landforms; ii) four host tree species; and iii) the truffle brûlé, i.e., the area lacking herbaceous cover when root colonization by T. aestivum occurs.Results show that combined variations in chemical and physical properties determined by soil forming processes can make an area suitable or not for T. aestivum. The establishment of brûlé and higher ascocarp production occurred in the more alkaline and less compact soil type, where the resistance to ascocarp volume enlargement is lower and aeration of the soil surface layer is higher. The tillage carried out in the truffle orchard presumably mimicked the effect of the brûlé on the soil structure, allowing the enlargement of the productive area outside the brûlé itself and showing how the management of a truffle plantation, even if sub-optimal for T. aestivum colonization, can influence its productive capacity. Our results further suggest that even in the best environmental conditions not all host trees will enter in production, while in less suitable soil conditions little or no production should be expected.

Optimal design of shape changing mechanical metamaterials at finite strains

Programmable metamaterials establish a new subset of metamaterials offering controllable and variable physical properties. As metamaterials, they are artificial materials and exhibit exotic and counter-intuitive material behavior, but are more specifically tailored for engineering purposes. Whereas for metamaterials a mostly homogeneous layout of unit cells is considered, programmable materials are constructed by an individual distribution in order to satisfy custom intentions regarding a specific shape change under given loading conditions. In order to tackle this customization of material response, a computational optimization framework similar to topology or material optimization is proposed. Our work is based on a multiscale and data approach, allowing a broad range of application with different classes of unit cells and target functions under finite strains. In this contribution, we present the complete process chain from a parametrized unit cell to the final model of the programmable material, ready to be manufactured. We show numerical results with different unit cells and compare them to fully resolved simulations. Further, with the development of new generative manufacturing processes, the production of such programmable materials consisting of spatially varying cells has also become possible on an industrial scale. One example of lab-scale production is shown in the paper and compared to simulation results.

A comparative study of different viscosity models for unsteady flow over a decelerating rotating disk with variable physical properties

The classical Von-Kármán infinite disk problem is one of the few fluid mechanics problems that demonstrates both theoretical and practical significance. Furthermore, temperature has a strong effect on fluid viscosity in various fluid situations particularly where considerably high operating temperatures are employed. Momentum and thermal boundary layer formations around a decelerating rotating disk in an otherwise calm environment are considered. Main interest here is to account for the temperature dependency in both viscosity and thermal conductivity. New computational results for liquids with two different viscosity models are derived in this study. Whole analysis is conducted by assuming slip effects at the boundary, which yield non-linear Robbin-type boundary conditions for radial and azimuthal velocity components. In addition, disk is allowed to expand radially with linearly varying velocity. A generalized set of transformations is invoked that enabled a self-similarity analysis of flow model accounting for temperature-dependent properties. For the numerical solution, we relied on a reliable routine bvp4c of software MATLAB. A comparative study of different variable viscosity models is also undertaken. It is concluded that neglecting temperature dependence of viscosity or thermal conductivity can lead to inaccurate predictions of the model

Effect of recreation on the spatial variation of soil physical properties

Recreation affects various components of ecosystems. A significant transformation occurs in the soil cover in urban parks. The physical properties of soil are sensitive indicators of the level of anthropogenic transformation, and also allow to assess the state of soil as a habitat for plants and soil animals. The question of quantitative patterns of soil properties variability under the influence of recreation is not solved. There is also little information on the spatial aspect of the variability of soil physical properties in urban ecosystems. The aim of our study is to test the hypothesis that the recreational loads cause the formation of spatial patterns of soil properties, which by their extent greatly exceed the zone of direct influence. The spontaneous walkways within an urban park were investigated as an example of recreational loading. The physical soil properties were measured on a regular grid. The distance to the walkway was treated as a proxy variable that indicates recreational load. The application of multivariate statistical methods allowed to reveal the components of the variation of soil properties of different nature. The effect of recreational load is superimposed on the natural variability of properties. The peculiarity of the influence of recreation consists in sharp increase of soil penetration resistance in the upper soil layers and decrease of this index in the lower layers. The recreational load affects the physical properties of the soil. The soil compaction is the main direction of transformation. This effect gradually attenuates with distance from the source of exposure while occupying a significant portion of the space. The variation of soil properties affects the redistribution of soil moisture and soil air, which significantly affects the living conditions of soil biota.

A Review Study on Theoretical Comparison Between Time-Dependent Analysis Models for Prestressed Concrete Bridges

Particularly, concrete material involvements creep under a continuous load and practices shrinkage due to variations in humidity proportion. These physical properties variations growth over time. Prestressed losses according to concrete creep and shrinkage will lead to loss of compression strength for concrete. Time-dependent analysis is important and essential for two types of prestressed concrete which are pretensioned and posttensioned with the effect of time, variations in the structural pattern, and high erection loads influence the structural performance and protection of structure for the duration of erection and when complete. Creep and shrinkage are the main time-dependent parameters of concrete. They are important parameters in the design of prestressed concrete structures such as bridges. The objective of this study is to review the analysis models of time-dependent parameters for prestressed concrete bridges by using shrinkage and creep factors equations to determine the strain of time-dependent parameters. Creep and shrinkage parameters were selected to review the effect of these parameters on the properties of prestressed concrete. Nine analysis methods for creep and shrinkage of concrete were reviewed in this study. These models include ACI-209 model, PCI-BDM model, CEB-FIP-90 model, AASHTO-LRDF model, Shams and Kahan model, NCHRP-496 model, B3 model, GL2000 model, and AFREM model. It was recommended that using this methodology to determine shrinkage and creep factors for prestresssed concrete bridge and comparing between the results of analysis models.

ВИКОРИСТАННЯ ВОДНЯ В ЕНЕРГЕТИЦІ

As a result of the conducted literature research the experimentally fixed positions about features of the hydrogen-induced deformation of a palladium plate are described. It is determined that when hydrogen saturation in the metal, a temporary gradient material "metal-hydrogen" is formed and hydrogen stress concentrations always occur. This in turn provides effective planning and determination of the time of penetration of hydrogen into the metal. The obtained experimental facts allow to control the change of shape and regulate the modes of operation of the fuel cell during the operation of the products. It is described that the maximum bending of the plate occurs at a constant temperature, and is determined by two fundamental properties of the palladium system - hydrogen, namely, the diffusion coefficient and equilibrium solubility of hydrogen in palladium. However, when the temperature changes, the diffusion coefficient of hydrogen in palladium and the equilibrium concentration of hydrogen in palladium changes, which determines the temperature dependence of the final bending of the plate and its change) when interacting with hydrogen. The scientific novelty is the use of the known material palladium, which in contact with hydrogen becomes a temporary gradient alloy with variable physical properties. It is established that the heat exchange in the plate and the energy balance around the plate depends on the rate of interaction of hydrogen and material, as well as the rate of heat flux that occurs during chemical reactions in fuel cells and heat loss in the fuel cell. The practical significance of the work lies in the possibility of using certain physical bases in practice in the manufacture of specific devices that work as a fuel cell with hydrogen. You can also model this process in MaCad and improve the operating conditions of fuel cells and hydrogen sensors, because at low temperatures there is a relatively small residual bending of the main components, and accordingly there are changes in the shape of these components.

A computational study on the MHD Casson fluid flow with thermal radiation and variable physical properties under the influence of Soret and Dufour effects

AbstractThis research study discusses the flow of a magnetohydrodynamic Casson fluid under the influence of Soret, Dufour, and thermal radiation. Nonlinear partial differential equation (PDE) of governing equations is transformed into a dimensionless version of the modified PDEs presented in terms of dimensionless parameters. The solution of coupled PDEs is obtained by the finite difference method with a combination of the quasilinearization technique. The effects of various dimensionless parameters are shown graphically, such as buoyancy force (), concentration buoyancy force , Casson parameter (), magnetic parameter (), thermal radiation (), Darcy parameter (), Forchheimer (fr), Dufour (), Soret (Sor), Brownian motion (), thermopohersis (), and Lewis number (). Prevention of heat transfer in the industrial system is critical, the velocity behavior (), thermal variation (), and concentration profile () are more prominent in the roles of coal, gas, and solar thermal collectors.

Study on the Heat Transfer and Ablation Characteristics of the Dual-Pulse Motor during the Working Process of the Barrier

In this paper, aiming at the problem of heat transfer and ablation prediction of phenolic resin/nitrile rubber in the insulation material in double pulse motor, based on pyrolysis kinetics and thermochemical ablation theory, a variable heat physical property model of nitrile rubber insulation material with temperature and time was established. A simulation study on the thermal diffusion and pyrolysis ablation of the barrier insulation materials was carried out. The ablation thickness and ablation rate of the barrier insulation material were obtained. The results show that the proposed ablation calculation model has a certain reference value for the ablation research of thermal insulation materials.

Assessment of some drinking water plants efficiency at El-Menofeya Governorate, Egypt

This study was conducted to investigate water quality from inlets and outlets of four drinking water treatment plants (DWTPs) at El-Menofeya Governorate, Egypt. Results obtained from four seasonal trips (from January to December 2018) revealed variation in chemical, physical and microbiological properties of El-Rayah El-menofy. Some inlets (El-Bagour, Menof and Shibin El-Kom) recorded high concentrations of ammonia, biological oxygen demand, chemical oxygen demand, total alkalinity and depletion in dissolved oxygen. Total coliforms, fecal coliforms and fecal streptococci exceeded permissible limits of law 48/1982 for DWTPs inlets, while for DWTPs outlets are within the permissible standard limits of law 458/2007. The water quality index (WQI) categorized the plants inlets as being medium, while for plants outlets as being good. Six bacterial strains were discovered in DWTPs inlets by molecular analysis showed different 16s rRNA-gene sizes. Krona test showed varied appendance percentages, 99%, 67%, 6.2% and 4.9% Escherichia coli, Enterococcus faecalis, Staphylococcus aureus and Pseudomonas aeruginosa in all DWTPs inlets. Nucleotide sequence data for bacterial strains were submitted to the NCBI GenBank database, USA and gained their accession numbers. Concluding remarks justify the strong correlation (r = +0.80) between physicochemical and bacteriological indicators in polluted aquatic ecosystems. The study recommends the protection of raw water resources from pollution by enforcement of actual applying of Egyptian laws coupled with rising the efficiency of water purification plants to ensure safe drinking water free of disease-causing agents.

Heat transport properties within living biological tissues with temperature-dependent thermal properties

Understanding of the heat transport within living biological tissues is crucial to effective heat treatments. The heat transport properties of living biological tissues with temperature-dependent properties are explored in this paper. Taking into account of variable physical properties, the governing equation of temperature is first derived in the context of the dual-phase-lags model (DPL). An effective method, according to the Laplace transform and a linearization technique, is then employed to solve this nonlinear governing equation. The temperature distribution of a biological tissue exposed to a pulsed heat flux on its exterior boundary, which frequently happens in various heat treatments, is predicted and analyzed. The results state that a lower temperature can be predicted when temperature dependence is considered in the heating process. The contributions of key thermal parameters are different and dependent on the ratio of phase lag and the amplitude of the exterior pulsed heat flux.

Characterization of Indonesian Banana Species as an Alternative Cellulose Fibers

ABSTRACT The pseudostem of banana (Musa sp.) has a high value for fiber. In this study, we characterized two wild Musa acuminata, i.e., ssp. malaccensis (LIPI-030) (M1) and var. breviformis (LIPI-218) (M3), an accession of diploid M. acuminata cultivar “Pisang Rejang” (LIPI-048) (M2) and one accession M. balbisiana “Pisang Klutuk” (LIPI-054) (M4) for its chemical (including Syringyl (S) and Guaiacyl (G) ratio) physical and mechanical properties, fiber analysis, morphological analysis, functional groups, crystallinity, and thermal analysis. As a result, there are variations in chemical, physical, and mechanical properties, fiber length and diameter, crystallinity, and thermal analysis behavior for each banana species. “Pisang Klutuk” showed the most different characteristics compared to others. The cellulose content of all banana fibers has a close correlation with their tensile strength. Based on the fiber properties evaluation, var. breviformis (M3) has a tensile strength of 459.99 MPa, cellulose content of 33.30%, degree of crystallinity of 45.23%, degree of polymerization of 1199.15, and S/G ratio of 0.39 that suggested the most potential banana for fiber with high strength. The lignin S/G ratio of banana samples (M1-M2) showed a positive correlation with the degree of crystallinity and tensile strength, while it had a negative one with tensile modulus and strain. This study presented the importance of the S/G ratio and fiber properties that may aid the future application of Indonesian fiber in biomass conversion strategies.

Development of Low-Cost and Multi-Material Sensing Approach for MQ 135 Sensor

Gas tracking systems in factories and companies have become very critical. The most effective and most important element in these systems is the gas sensor. In this study, MQ 135 (butane and smoke) modified to sense common and harmful gases using a low-cost approach. The processor modified the sensor response unit to respond to hydrogen, carbon monoxide, and chlorine gases. Due to variation in physical properties between these gases mainly density, the gas rise on the air to the detector is different. Consequently, the response time for detection was different. It takes 9, 15, 33, and 36 sec. for butane, hydrogen, carbon monoxide, and chlorine gases, respectively. The cost reduction of the MQ 135 sensor reduced by 80%.

Mechanical and Moisture Barrier Properties of Epoxy-Nanoclay and Hybrid Epoxy-Nanoclay Glass Fibre Composites: A Review.

Epoxy clay nanocomposites have been proven to have improved mechanical, thermal and physical properties over pristine matrix. Thus, the fields of application of epoxy–clay nanocomposites along with their hybrid glass/carbon fibre reinforced composites have grown tremendously during the last few decades. The present review paper covers the research work performed on epoxy clay nanocomposites. It includes the influence of the processing techniques and parameters on the morphology of the nanocomposite, the methods of characterization and the effects of adding nanoclay on the mechanical and physical properties of composite. The improvements in the liquid barrier properties brought about by the addition of nanoclay platelets to epoxy resin are discussed. The variation of physical and mechanical properties with nanoclay type and content are reviewed along with the effects of moisture uptake on these properties. The advances in the development, characterization and applications of hybrid glass fibre reinforced epoxy–clay nanocomposites are discussed. Findings of the research work on the influence of nanoclay addition and exposure to water laden atmospheres on the behaviour of the hybrid glass fibre epoxy–nanoclay composites are presented. Finally, the potential health and environmental issues related to nanomaterials and their hybrid composites are reviewed.

Multi-layer model for moving contact problems of functionally graded coatings with general variations in physical properties

This paper presents a multi-layer model for moving contact problems of functionally graded coatings whose physical properties have general spatial variations. The coating is assumed to be composed of an arbitrary number of layers and perfectly bonded to an elastic substrate. Wave equations for the layers and the substrate are derived in accordance with the plane theory of elastodynamics. The equations are solved by the application of Galilean and Fourier transformations. Flat and triangular punch profiles are considered, and the formulation is reduced to a singular integral equation of the second kind in both cases. The integral equations are solved by means of Jacobi expansion and collocation techniques. Proposed procedures are verified through comparisons to the results available for a special case in the literature. Parametric analyses are carried out for functionally graded coatings possessing ceramic-rich, metal-rich, and linear profiles. The results presented demonstrate the influences of factors such as punch speed, coefficient of friction, material property variation profile, and contact-length-to-thickness ratio on contact stresses, punch stress intensity factors, and required contact force. It is shown that the multi-layer model is required to account for general property distributions in a functionally graded coating subject to moving contact.

Fiber digestibility in growing pigs fed common fiber-rich ingredients – A systematic review

Abstract The application of high-fiber ingredients in the swine feed industry has some limitations considering that high amounts of fiber are resistant to endogenous enzymatic degradation in the pig’s gut. However, there is growing interest in fiber fermentation in the intestine of pigs due to their functional properties and potential health benefits. Many strategies have been applied in feed formulations to improve utilization efficiency of fiber-rich ingredients and stimulate their prebiotic effects in pigs. This manuscript reviews chemical compositions, physical properties, and digestibility of fiber-rich diets formulated with fibrous ingredients for growing pigs. Evidences presented in this review indicate there is a great variation in chemical compositions and physical properties of fibrous ingredients, resulting in the discrepancy of energy and fiber digestibility in pig intestine. In practice, fermentation capacity of fiber components in the pig’s intestine can be improved using strategies, such as biological enzymes supplementation and feed processing technologies. Soluble dietary fiber (SDF) and insoluble dietary fiber (IDF), rather than neutral detergent fiber (NDF) and acid detergent fiber (ADF), are recommended in application of pig production to achieve precise feeding. Limitations of current scientific research on determining fiber digestibility and short chain fatty acids (SCFA) production are discussed. Endogenous losses of fiber components from non-dietary materials that result in underestimation of fiber digestibility and SCFA production are discussed in this review. Overall, the purpose of our review is to provide a reference for feeding the pig by choosing the diets formulated with different high-fiber ingredients.

Influences of fluid physical properties, solid particles, and operating conditions on the hydrodynamics in slurry reactors

Slurry reactors are popular in many industrial processes, involved with numerous chemical and biological mixtures, solid particles with different concentrations and properties, and a wide range of operating conditions. These factors can significantly affect the hydrodynamic in the slurry reactors, having remarkable effects on the design, scale-up, and operation of the slurry reactors. This article reviews the influences of fluid physical properties, solid particles, and operating conditions on the hydrodynamics in slurry reactors. Firstly, the influence of fluid properties, including the density and viscosity of the individual liquid and gas phases and the interfacial tension, has been reviewed. Secondly, the solid particle properties (i.e., concentration, density, size, wettability, and shape) on the hydrodynamics have been discussed in detail, and some vital but often ignored features, especially the influences of particle wettability and shape, as well as the variation of surface tension because of solid concentration alteration, are highlighted in this work. Thirdly, the variations of physical properties of fluids, hydrodynamics, and bubble behavior resulted from the temperature and pressure variations are also summarized, and the indirect influences of pressure on viscosity and surface tension are addressed systematically. Finally, conclusions and perspectives of these notable influences on the design and scale-up of industrial slurry reactors are presented.

Preparation of an Antimicrobial and Antioxidant Bio-Polymer Film and Its Application as Glazing Shell for Postharvest Quality of Fresh-Cut Apple.

The aim of this work is to glazing a modified bio-polymer shell as substitute of peel to keep the postharvest quality of fresh-cut fruits. In this study, chitosan as backbone of the shell was modified by addition of the functional extracts obtained from Zanthoxylum, in which 12 kinds of main identified bio-active components consisted of over 55% of the total extracts. The introduction of the extracts improved physic and mechanical properties of the shell, and endowed it with significant antimicrobial and antioxidant activity. Accordingly, the modified chitosan was used as the substitute of peel to preserve fresh-cut apples. Results exhibited that such treatments obviously delayed the decline process of overall postharvest quality of the preserved apple samples throughout all the storage period, represented by the variations in physical, chemical, and microbial properties of the apple samples were significantly inhibited. The overall observations revealed promising potential of the bio-polymer shell in food application.

The Assessment of Endovascular Therapies in Ischemic Stroke: Management, Problems and Future Approaches.

Ischemic stroke accounts for over 80% of all strokes and is one of the leading causes of mortality and permanent disability worldwide. Intravenous administration of recombinant tissue plasminogen activator (rt-PA) is an approved treatment strategy for acute ischemic stroke of large arteries within 4.5 h of onset, and mechanical thrombectomy can be used for large arteries occlusion up to 24 h after onset. Improving diagnostic work up for acute treatment, reducing onset-to-needle time and urgent radiological access angiographic CT images (angioCT) and Magnetic Resonance Imaging (MRI) are real problems for many healthcare systems, which limits the number of patients with good prognosis in real world compared to the results of randomized controlled trials. The applied endovascular procedures demonstrated high efficacy, but some cellular mechanisms, following reperfusion, are still unknown. Changes in the morphology and function of mitochondria associated with reperfusion and ischemia-reperfusion neuronal death are still understudied research fields. Moreover, future research is needed to elucidate the relationship between continuously refined imaging techniques and the variable structure or physical properties of the clot along with vascular permeability and the pleiotropism of ischemic reperfusion lesions in the penumbra, in order to define targeted preventive procedures promoting long-term health benefits.

Effect of stem height in variation of bark, heartwood, sapwood and physical properties of wood in <i>Dipteryx panamensis</i> Pittier in a provenance/progeny test

Dipteryx panamensis is used in reforestation in Costa Rica and a genetic improvement program has been recently started in the country. The objective of the present study was to study the effect of tree trunk height on the variation of bark, sapwood, heartwood, green density (GD), specific gravity (SG) and green moisture content in green condition (MC-G), in a collection of 8-year-old provenances/progenies planted in the town of Florencia in San Carlos in the northern region of Costa Rica The wood of each of 17 families were studied based on 3 of their progenies, evaluating the properties relative to 0, 25%, 50%, 75% and 100% of the commercial height. According to the results, tree diameter and bark thickness showed no statistical differences in their values across trunk. Significant differences were found in diameter and percentage of heartwood and sapwood between provenances and families. The thickness and percentage of sapwood, thickness and percentage of bark, diameter, pith percentage and percentage of pith eccentricity, showed no significant differences between families. SG and the MC-G presented significant variation between provenances, while GD registered differences at above 25 % commercial height. The variation of physical properties, especially SG, between families within each provenance, shows selection potential for genetic improvement, focusing particularly on the bottom section of the tree.

Studying the optical and physical properties of aerosolin an urban area of Hanoi city

The purpose of this study is to analyse and evaluate the optical and physical properties of aerosol in an urban area of Hanoi city based on the data products for aerosol characteristics measured by the sunphotometer situated at the ground station (Nghia Do AERONET station, Hanoi) and by the MODIS satellite remote sensing for 3 seasons (dry, rainy, and transitional seasons) during the period of 2010-2018. The findings showed that the aerosol optical depth (AOD) has the highest value in the transitional season (1.24), followed by those in the dry (0.94) and rainy (0.57) seasons. The high value of Angstrom Exponent (1.34) measured at the wavelengths of 870 and 440 nm (AE440-870) indicated the major contribution of fine particles, compared to that by the coarse particles, in the aerosol loading in the study area. The high values of both Extinction Angstrom Exponent (EAE440-480) and Absorbed Angstrom Exponent (AAE440-480) during 3 seasons suggested that aerosol originated from both biomass burning and urban/industrial sources co-existed in the atmosphere in the study area. The analysis results for active fires in the Southeast Asia measured by MODIS satellite and air mass backward trajectories arrived at the study site in Hanoi in the periods of 2016 showed that the regional biomass burning activities (the central region of Vietnam and neighboring countries including Thailand, Laos, and Cambodia) could be the important source influencing the variation of optical and physical properties of aerosol during the end of the dry season and transitional season in the urban area of Hanoi city.