Liming of alfalfa in a greenhouse study

The use of agricultural lime has been recognized down through the ages as a practice that is basic to good soil management in humid regions. The effects of liming are a complex of many contributing physical, chemical. microbiological and physiological factors. Its direct function is to correct soil acidity, improve soil structure and create an environment suitable to the growth and development of plants. Liming enhances the availability and plant uptake of elements such as nitrogen, phosphorus, molybdenum, calcium, and magnesium. At the same time it drastically reduces the concentration of iron, aluminum and manganese, which under very acid conditions are apt to be present in toxic quantities. In at least some soils, it enhances the availability of potassium. Lime stimulates the general-purpose. heterotrophic soil organisms, thereby increasing their activity on organic matter and the releasing of nitrogen. This favors the formation of humus and also encourages the elimination of certain intermediate products that might be toxic to higher plants. Within the plant, too, lime performs many functions. Calcium is essential for the growth of the meristems. the development and functioning of root tips, and for certain enzymatic reactions involved in respiration. The uptake of nutrients by roots of plants from the soil medium is a complex physiological process, the rate of which is greatly influenced by environmental factors. Greenhouse experiments have several advantages in this regard, most important of which is the control of numerous environmental factors. It is also possible under greenhouse conditions to design experiments to include a large number of treatments and a variety of soils; they can be carried out at any time of the year Irrespective of the season. Furthermore, Investigations of a fundamental nature such as soil-plant relationships, can be made in a greenhouse without the involvement of elaborate field studies, high cost and undue labor. At the same time, they can serve as pilot projects for appropriate field studies in the future. The influence of lime on acid soils in promoting the growth, yield and uptake of nutrients is one of fundamental importance and immediate concern to the agronomist. Lime-fertilizer experiments in the greenhouse involving the use of calcium, phosphorus and potassium on acid infertile soils are therefore very important in giving some indication as to the wise use of these nutrients. Since root development of crops in acid soils is very much dependent on the soil condition, its lime content and the nature of its zone of penetration, the placement of lime as an additional factor in the balance of fertilization assumes relatively great importance. This work was undertaken with the following objectives in view: 1. To study the influence of liming and fertilization of an acid soil on growth, yield, root development and uptake of various cations by plants. 2. To study the influence of placement of lime in different layers of the soil on the above factors. Hartsells loam was the soil used for the study. It was low in all nutrients. Alfalfa was used as the indicator plant because it is known to be sensitive to soil acidity

Simultaneous removal of polycyclic aromatic hydrocarbons and heavy metals from water using granular activated carbon

© 2019 Elsevier Ltd Polycyclic aromatic hydrocarbons (PAHs) and heavy metals are dangerous pollutants that commonly co-occur in water. An adsorption study conducted on the simultaneous removal of PAHs (acenaphthylene, phenanthrene) and heavy metals (Cd, Cu, Zn) by granular activated carbon (GAC) showed that, when these pollutants are present together, their adsorption was less than when they were present individually. The adsorptive removal percentage of PAHs (initial concentration 1 mg/L) was much higher than that of heavy metals (initial concentration (20 mg/L). The reduction in adsorption of PAHs by heavy metals followed the heavy metals' adsorption capacity and reduction in the negative zeta potential of GAC order (Cu > Zn > Cd). In contrast, PAHs had little effect on the zeta potential of GAC. The Langmuir adsorption capacities of acenaphthylene (0.31–2.63 mg/g) and phenanthrene (0.74–7.36 mg/g) on GAC decreased with increased metals' concentration with the reduction following the order of the metals’ adsorption capacity. The kinetic adsorption data fitted to Weber and Morris plots, indicating intra-particle diffusion of both PAHs and heavy metals into the mesopores and micropores in GAC with the diffusion rates. This depended on the type of PAH and metal and whether the pollutants were present alone or together

Optimization of NaCl based spray corrosion test process parameters of heat treated hybrid metal matrix composites

ABSTRACT. Aluminium hybrid metal matrix composites (AHMMCs) have widely employed in aerospace, transportation, and automotive applications since for their excellent mechanical qualities and high corrosion resistance. In this research, Al8079 is selected as a matrix material. The titanium diboride (TiB2) is selected as hard reinforcement and molybdenum disulfide (MoS2) is used as soft reinforcement. The Al8079/15 wt.% TiB2/x wt.% MoS2 (x = 0, 2.5, 5 and 7.5) HMMCs are fabricated by using stir casting. The composites are heat treated under T6 condition. The density and micro hardness tests are conducted. The optimization on NaCl based spray corrosion test process parameters is done using grey relational analysis (GRA). The selected input process parameters are Al8079/15 wt.% TiB2/wt.% MoS2 (x = 0, 2.5 and 5), pH value of NaCl solution (x = 6, 9 and 12), hang time (x = 24, 48, and 72 h) and pressure (x = 0.7, 0.9 and 1.1 kg/cm2). The selected response parameters are micro hardness, mass loss and wear loss. The L9 Taguchi design is used for optimization. The wear test is conducted at the constant speed of 0.5 m/s, loading rate of 20 N and the sliding distance of 1000 m. The percentage of improvement of GRG from initial setting to experimental is 10.4%.   KEY WORDS: Reinforcement, Stir casting, Optimization, GRA, NaCl Bull. Chem. Soc. Ethiop. 2022, 36(4), 903-914.                                                         DOI: https://dx.doi.org/10.4314/bcse.v36i4.1

Mining valuable minerals from seawater: A critical review

©2017 The Royal Society of Chemistry. Seawater contains large quantities of valuable minerals, some of which are very scarce and expensive in their land-based form. However, only a few minerals, the ones in high concentrations, are currently mined from the sea. Due to recent problems associated with land-based mining industries as a result of depletion of high-grade ores, sustainable water and energy demand and environmental issues, seawater mining is becoming an attractive option. This paper presents a comprehensive and critical review of the current methods of extracting valuable minerals from seawater and seawater brines generated in desalination plants, and suggests ways to overcome some of the limitations and challenges associated with the extraction process. The extraction methods discussed are solar evaporation, electrodialysis (ED), membrane distillation crystallisation (MDC), and adsorption/desorption

Work practices of onsite construction crews and their influence on productivity

© 2018 by the author(s). The nature of construction work processes allow crews and workers to follow their own practices in how they plan, organise and coordinate work. However, there is little research into the nature of crew work practices. This paper aims to unveil the influence of onsite crew work practices on productivity. An exploratory case study investigated work practices on a residential project involving two separate crews (of 18 and 23 workers) engaged in rebar placement for 112 columns each, which included a high-performing and an average-performing crew. A triangulated mixed methods approach to data gathering utilised site observations, individual and group interviews, and time measured work studies, to assess productivity of the crews. The findings indicate that the high-performing crew achieved 44% higher productivity than the average-performing crew and this manifested across specific tasks including rebar cutting, bending, stirrup fabrication and tieing. Five broad work practices were observed to considerably influence the above productivity differences: work preparation and execution strategy; group formation and stability; avoiding duplication of tasks; crew social cohesion; and internal and external leadership practices. These five practices are proposed as dimensions that can be used to measure crew productivity in ongoing research. In-depth understanding of crew based work practices will enable training of foremen and work crews in such practices to systematically develop high-performing crews

Effect of soaking time and concentration of NaOH solution on mechanical properties of coir-polyester composites

The green husk coir fibres were treated with different levels of soaking time and concentration of alkali solution. As a result of alkali treatment, the surface modifications were done on the fibre surface and were studied using scanning electron micrographs. The coir–polyester composites were fabricated using hand lay up process and the mechanical properties (tensile, flexural and impact strength) were evaluated as per ASTM standards. The effect of soaking time and concentration of NaOH solution were studied based on evaluated values of mechanical properties to find out optimum fibre treatment parameters

Removal and recovery of phosphate from water using sorption

Sorption is an effective, reliable, and environmentally friendly treatment process for the removal of phosphorus from wastewater sources which otherwise can cause eutrophication of receiving waters. Phosphorus in wastewater, if economically recovered, can partly overcome the future scarcity of phosphorus resulting from exhaustion of natural phosphate rock reserves. The authors present a comprehensive and critical review of the literature on the effectiveness of a number of sorbents, especially some novel ones that have recently emerged, in removing and recovering phosphate. Mechanisms and thermodynamics of sorption, as well as regeneration of sorbents for reuse using acids, bases, and salts, are critically examined. © 2014 Copyright Taylor & Francis Group, LLC