scholarly journals Um panorama das propriedades físicas e químicas de substratos utilizados em horticultura no sul do Brasil

2015 ◽  
Vol 21 (3) ◽  
pp. 299 ◽  
Author(s):  
Gilmar Schafer ◽  
Paulo Vitor Dutra de Souza ◽  
Claudimar Sidnei Fior
Keyword(s):  
Electrical Conductivity ◽  
Total Porosity ◽  
Chemical Characteristic ◽  
Physical Characteristics ◽  
Water Retention Curve ◽  
Chemical Analyses ◽  
Retention Curve ◽  
Commercial Laboratory ◽  
Wide Range ◽  
Physical And Chemical

The cultivation in greenhouse and containers culminated with the necessity to use substrates with formulations as well as distinguished chemical and physical characteristics, the last ones assuming a key role in cultivation of horticultural plants. The aim of this study is to present results of physical and chemical analyses of substrates forwarded to an commercial laboratory (Laboratório de Substratos para Plantas - UFRGS) for the last three years, aiming to establishing a panorama of the substrates area and comparing them with reference values cited in the literature. In this period were performed 307 physical and 479 chemical analyses, which were the basis for this study. Physical analyses performed were the density in dry basis and the water retention curve (total porosity, air space, available water and remaining water). Chemical analyses were the electrical conductivity (EC) and the pH. The main results concerning physical characteristics, demonstrate that the substrates present wide range of density in dry basis and may be used for different sized containers; however most substrates analyzed is out of ideal range for the other physical characteristics of the substrate. For the chemical characteristic the substrates in cultivation in southern Brazil are mostly alkaline and the electrical conductivity of the substrates in cultivation is very diverse, with considerable number of samples above the recommended.

scholarly journals Watertable fluctuation-induced variability in the water retention curve: Sand column experiments

2020 ◽  
Author(s):  
Zhaoyang Luo ◽  
Jun Kong ◽  
Zhiling Ji ◽  
Chengji Shen ◽  
Chunhui Lu ◽  
...  
Keyword(s):  
Water Content ◽  
Capillary Pressure ◽  
Soil Water ◽  
Soil Water Content ◽  
Water Retention ◽  
Water Retention Curve ◽  
Water Flow Velocity ◽  
Retention Curve ◽  
Wide Range ◽  
Static Conditions

<p>The soil water retention curve (WRC), describing the relation between the soil water content and its corresponding capillary pressure, relies not only on whether drying or wetting occurs but also on the pore scale water flow velocity. Here, we investigated the effects of the watertable fluctuations on the WRC through 28 laboratory experiments covering a wide range of fluctuation amplitudes and periods. Results show that both the response of the capillary pressure and soil water content lag behind the watertable fluctuation, and the vertical capillary pressure distribution in the unsaturated zone is non-hydrostatic, especially for the fluctuations with shorter period. As a consequence of watertable fluctuation, the measured WRC deviates from that under static conditions, depending on both the fluctuation amplitude and period. Moreover, the air-entry pressure under dynamic conditions is considerably larger than that under static conditions, and it first increases and then decreases as the fluctuation period decreases. The effects of the watertable fluctuations on the dynamic capillary coefficient was further examined. It is found that the relation between the dynamic capillary coefficient and saturation is nonunique even for the drying and wetting of a given sand and watertable fluctuation, suggesting a hysteretic dynamic capillary coefficient, and the dynamic capillary coefficient is rate-dependent, decreasing with an increase of fluctuation rate.</p>

Influence of chemical composition and inorganic admixtures on the electrical conductivity of hydrating cement pastes

1989 ◽  
Vol 4 (1) ◽  
pp. 215-223 ◽  
Author(s):  
M. Perez-Pena ◽  
D. M. Roy ◽  
F. D. Tamás
Keyword(s):  
Electrical Conductivity ◽  
Cementitious Materials ◽  
Heat Of Hydration ◽  
Chemical Compositions ◽  
Chemical Parameters ◽  
Cement Pastes ◽  
Rate Of Development ◽  
Wide Range ◽  
Physical And Chemical Parameters ◽  
Physical And Chemical

Electrical conductivity of cementitious materials with a wide range of chemical compositions has been studied during the first 24 h of hydration. Relationships between heat of hydration and electrical conductivity curves are discussed. Results are tentatively explained in terms of some physical and chemical parameters. Further evidence that the electrical conductivity of hydrating cement pastes is related to the hydration mechanisms operating in these systems was obtained. The order in which the cations of inorganic admixtures (chlorides and hydroxides) were found to increase the peak and rate of development of the electrical conductivity is the same order that they have been found to increase the heat liberated upon hydration of systems containing these admixtures.

Evaluating the Splintex model for estimating the soil water retention curve for a wide range of soils

2021 ◽  
Vol 209 ◽  
pp. 104974
Author(s):  
Alessandra Calegari da Silva ◽  
Robson André Armindo ◽  
Budiman Minasny ◽  
Celso Luiz Prevedello
Keyword(s):  
Soil Water ◽  
Water Retention ◽  
Water Retention Curve ◽  
Soil Water Retention Curve ◽  
Soil Water Retention ◽  
Retention Curve ◽  
Wide Range

scholarly journals Comparison of Mathematical Models for the layout of Granulometric Curves of Brazilian Soils

2017 ◽  
Vol 34 (1) ◽  
Author(s):  
Willames Albuquerque Soares ◽  
Claude Hammecker
Keyword(s):  
Water Retention ◽  
Soil Mechanics ◽  
Classification Systems ◽  
Solid Particles ◽  
Water Retention Curve ◽  
Statistical Parameters ◽  
Retention Curve ◽  
Tuning Parameters ◽  
Wide Range ◽  
Brazilian Soils

The particle size distribution of solid particles (PSD) is critical in determining the potential for compaction, the availability and the redistribution of water in the soil, especially in the areas of building material and soil mechanics, among others. However, many banks of soil data does not contain detailed PSD data, but only some fractions. A mathematical accurate representation of the PSD is required to estimate soil hydraulic properties and texture comparing measurements of different classification systems. The objective of this study was to compare the performance of 12 models, with 2 and 3 tuning parameters proposed in the literature to represent the PSD, and, predict the water retention curve in the soil, from a wide range of Brazilian soils textures. The statistical parameters (NDEs, RD, MS CRM) showed three models tuning parameters proposed by Lima & Silva, Weibull and Fredlund got the best performance, with lower NDE, RD, MS very close to one and CRM values very low. The models Lima & Silva, Weibul, Fredlund and Skaggs, with three tuning parameters, and the models Skaggs end Lima & Silva, with two parameters, proved to be suitable for estimate the water retention curve in the soil, for soils with coarse and fine texture. Keywords: Granulometry; Soil texture; Curve Adjustments. 

scholarly journals PENGGUNAAN KATALIS MgF2 DALAM SINTESIS SENYAWA TURUNAN AMOKSISILIN

2021 ◽  
Vol 4 (1) ◽  
pp. 7-13
Author(s):  
Hadi Barru Hakam Fajar Siddiq
Keyword(s):  
Melting Point ◽  
Bitter Taste ◽  
Chemical Characteristic ◽  
Physical Characteristics ◽  
Organoleptic Test ◽  
Point Test ◽  
Physical And Chemical ◽  
Brown Powder

The synthesis of amoxicillin derivatives was carried out by reaction of amoxicillin with p-aminophenol which was catalyzed by MgF2. The aims of this research was to characterize amoxicillin derivatives. The compounds have been characterized by physical and chemical tests including organoleptic test, melting point test, pH test, Rf value test and maximum wavelength test. The results showed that the compounds having physical characteristics including organoleptic was brown powder and bitter taste with 238°C melting point. The chemical characteristic showed that Rf value was about 0.6, a pH was 6,1 and a maximum wavelength was 311 nm.

scholarly journals Pore network of an Inceptisol under different uses and relativized S-index as an indicator of soil physical quality

2016 ◽  
Vol 51 (9) ◽  
pp. 1575-1583 ◽  
Author(s):  
Raimundo Nonato de Assis Júnior ◽  
Jaedson Cláudio Anunciato Mota ◽  
Alcione Guimarães Freire ◽  
Thiago Leite de Alencar
Keyword(s):  
Secondary Forest ◽  
Organic Matter Content ◽  
Total Porosity ◽  
Matter Content ◽  
Water Retention Curve ◽  
Intrinsic Permeability ◽  
Retention Curve ◽  
Soil Physical Quality ◽  
Agricultural Use

Abstract The objective of this work was to evaluate soil porous media quality under different uses, as well as to propose a new index to monitor changes in its structure due to management: the Srelative index. An Inceptisol under irrigated banana cultivation and secondary forest, in the Brazilian Apodi Plateau, was evaluated at three soil layers (0.0-0.1, 0.1-0.2, and 0.2-0.3 m) as to: particle size, particle and bulk density, organic matter content, intrinsic permeability to air, and water retention curve. Total porosity, index for pore continuity (defined by the ratio between soil intrinsic permeability to air and aeration porosity), volume of blocked pores, and the S and Srelative indices were determined. The Srelative index was calculated as the ratio between S-index values from undisturbed and disturbed samples of the same soil (Sundisturbed/Sdisturbed). Under the studied conditions, the Srelative index is a good quantifier of the changes imposed by soil use and management. Soil cultivation maintains or improves the quality of the evaluated attributes, except for blocked porosity, when compared with the soil under native secondary forest with ten years of regeneration after agricultural use.

INFLUENCE OF SOIL MATRIX ON SOIL-WATER RETENTION CURVE AND HYDRAULIC CHARACTERISTICS

2017 ◽  
Vol 16 (4) ◽  
pp. 869-877
Author(s):  
Vasile Lucian Pavel ◽  
Florian Statescu ◽  
Dorin Cotiu.ca-Zauca ◽  
Gabriela Biali ◽  
Paula Cojocaru
Keyword(s):  
Soil Water ◽  
Water Retention ◽  
Water Retention Curve ◽  
Hydraulic Characteristics ◽  
Soil Water Retention Curve ◽  
Soil Water Retention ◽  
Soil Matrix ◽  
Retention Curve

scholarly journals Palladium and Copper: Advantageous Nanocatalysts for Multi-Step Transformations

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1891
Author(s):  
Antonio Reina ◽  
Trung Dang-Bao ◽  
Itzel Guerrero-Ríos ◽  
Montserrat Gómez
Keyword(s):  
Chemical Properties ◽  
Added Value ◽  
Solid Supports ◽  
Nanosized Materials ◽  
Nano Structures ◽  
Liquid Phases ◽  
Wide Range ◽  
Synthetic Methodologies ◽  
Physical And Chemical ◽  
A Current

Metal nanoparticles have been deeply studied in the last few decades due to their attractive physical and chemical properties, finding a wide range of applications in several fields. Among them, well-defined nano-structures can combine the main advantages of heterogeneous and homogenous catalysts. Especially, catalyzed multi-step processes for the production of added-value chemicals represent straightforward synthetic methodologies, including tandem and sequential reactions that avoid the purification of intermediate compounds. In particular, palladium- and copper-based nanocatalysts are often applied, becoming a current strategy in the sustainable synthesis of fine chemicals. The rational tailoring of nanosized materials involving both those immobilized on solid supports and liquid phases and their applications in organic synthesis are herein reviewed.

Nanobiotechnology: Nature-inspired silver nanoparticles towards green synthesis

2021 ◽  
pp. 0958305X2198988
Author(s):  
Nur Syakirah Rabiha Rosman ◽  
Noor Aniza Harun ◽  
Izwandy Idris ◽  
Wan Iryani Wan Ismail
Keyword(s):  
Electrical Conductivity ◽  
Silver Nanoparticles ◽  
Green Synthesis ◽  
Metal Nanoparticles ◽  
Current Trend ◽  
Biological Properties ◽  
Noble Metal Nanoparticles ◽  
Current Application ◽  
Physical Chemical ◽  
Physical And Chemical

The emergence of technology to produce nanoparticles (1 nm – 100 nm in size) has drawn significant researchers’ interests. Nanoparticles can boost the antimicrobial, catalytic, optical, and electrical conductivity properties, which cannot be achieved by their corresponding bulk. Among other noble metal nanoparticles, silver nanoparticles (AgNPs) have attained a special emphasis in the industry due to their superior physical, chemical, and biological properties, closely linked to their shapes, sizes, and morphologies. Proper knowledge of these NPs is essential to maximise the potential of biosynthesised AgNPs in various applications while mitigating risks to humans and the environment. This paper aims to critically review the global consumption of AgNPs and compare the AgNPs synthesis between conventional methods (physical and chemical) and current trend method (biological). Related work, advantages, and drawbacks are also highlighted. Pertinently, this review extensively discusses the current application of AgNPs in various fields. Lastly, the challenges and prospects of biosynthesised AgNPs, including application safety, oxidation, and stability, commercialisation, and sustainability of resources towards a green environment, were discussed.

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