Mavinakere Eshwaraiah Raghunandan

Utilization of plant-based natural coagulants as future alternatives towards sustainable water clarification.

Rapid industrial developments coupled with surging population growth have complicated issues dealing with water scarcity as the quest for clean and sanitized water intensifies globally. Existing fresh water supplies could be contaminated with organic, inorganic and biological matters that have potential harm to the society. Turbidity in general is a measure of water cloudiness induced by such colloidal and suspended matters and is also one of the major criteria in raw water monitoring to meet the stipulated water quality guidelines. Turbidity reduction is often accomplished using chemical coagulants such as alum. The use of alum is widely associated with potential development of health issues and generation of voluminous sludge. Natural coagulants that are available in abundance can certainly be considered in addressing the drawbacks associated with the use of chemical coagulants. Twenty one types of plant-based natural coagulants categorized as fruit waste and others are identified and presented collectively with their research summary in this review. The barriers and prospects of commercialization of natural coagulants in near future are also discussed.

Preparation of reconstituted sand samples in the laboratory

Abstract This paper compares the void ratio obtained in samples prepared by dry and moist tamping, and dry and wet pluviation. These 4 methods are amongst the few other commonly adopted methods used in the preparation of reconstituted sand samples in the laboratory e.g. slurry deposition and vibration. The samples were prepared in 100mm diameter and 200mm long split moulds. The effects of the number of soil layers and the drop height of the tamper, on particle packing, were studied in the tamping method. Microscopic images of these samples showed that the packing was more compact between the interface of two adjacent layers in tamped samples. In the pluviation method, the distance through which the sand particles were rained and the mass-flow were the two investigated parameters. The mass-flow was varied with the use of 3 different funnel openings. Frictional drag because of the air was ignored in the pluviation tests. The dry pluviation results seem to suggest that up to the limiting mass-flow, the funnel opening has a greater influence on the void ratio than the height through which the sand is rained. Furthermore, the tendency of the medium to dense air pluviated samples to dilate in drained triaxial test was not evident in the wet pluviated samples. The dilation was otherwise observed to be the maximum in dry tamped samples.

Extraction of phytochemicals using hydrotropic solvents

ABSTRACT Every plant synthesizes phytochemicals with different properties to supply a pool of molecules for food, chemical and pharmaceutical applications. Concurrent with “green technology” development, use of green solvents to extract phytochemicals instead of conventional non-eco-friendly solvents is crucial. Hydrotrope is a one of the green solvents that enhances solubility of poorly water-soluble or hydrophobic compounds in aqueous solutions. This article critically reviews the extraction of phytochemicals using various hydrotropic solvents. Hydrotropy mechanisms, factors influencing extraction and recovery methods of phytochemicals were also evaluated in this review.

Compressive Strength of Compacted Clay-Sand Mixes

The use of sand to improve the strength of natural clays provides a viable alternative for civil infrastructure construction involving earthwork. The main objective of this note was to investigate the compressive strength of compacted clay-sand mixes. A natural clay of high plasticity was mixed with 20% and 40% sand (SP) and their compaction and strength properties were determined. Results indicated that the investigated materials exhibited a brittle behaviour on the dry side of optimum and a ductile behaviour on the wet side of optimum. For each material, the compressive strength increased with an increase in density following a power law function. Conversely, the compressive strength increased with decreasing water content of the material following a similar function. Finally, the compressive strength decreased with an increase in sand content because of increased material heterogeneity and loss of sand grains from the sides during shearing.

Chapter 8 – Carotenoids

Numerous epidemiological evidence has shown that the consumption of carotenoid-rich food lowers the risk of chronic diseases including various types of cancer and cardiovascular diseases. Most of the benefits of carotenoids are due to their robust antioxidant effects, which fuel the growth of today’s existing carotenoid-rich formulations. Progress in this field has become challenging due to increasing consumer preferences for nutritious and effectual carotenoid formulas with unmodified sensorial properties. Various new technologies have been developed by food industrialists to acquire and preserve carotenoids from natural sources on a long-term basis. This chapter focuses on the nutritional and functional properties of the main carotenoids as well as the modifications that processing with emerging technologies have brought to the field including their bioaccessibility, stability, and functional properties.

A review on the effect of rubber membrane in triaxial tests

This paper presents a review on the effect of rubber membranes on the measured stress and volume change data during the triaxial tests. In many instants, the error associated due to membrane penetration is measured to be close to the total sample volumetric strains. Hence, in addition to precise measurements, adopting an appropriate correction to the measured data is pivotal. This paper provides a detailed review on the methods used to estimate and reduce the influence of rubber membrane on the measured triaxial test results. The discussion therefore clearly highlights the stiffness, thickness, and diameter of the membrane used, to have significant influence on the measured deviatoric stress and the volume change data. The mean grain size of sample has an equally significant influence on the volume change. The methods in general are limited to test conditions, and therefore, it is practically uncertain to have a generalized correction procedure. Effectively, the outcome from this review work enhances the understanding of the reader towards the effect, methods, and corrections to be considered in triaxial testing due to rubber membrane and membrane penetration effects.

Compaction characteristics and strength of BC soil reinforced with untreated and treated coir fibers

Black cotton soils, because of its high swelling and shrinkage characteristics, have been a challenge to geotechnical engineers. Use of natural reinforcing materials in soil such as jute and coir has the advantage that they are available at low cost. Among the natural reinforcing fibers in soil, coir has the greatest tensile strength and retains its property even in wet conditions and has been used in many non-critical civil engineering applications. In the present study, compaction characteristics of black cotton soil (BC soil) admixed at different percentage of untreated and treated coir fibers were used with optimum lime content and without lime content. Alkali-treated and epoxy resin-coated and stone dust-sprinkled coir fibers have been comparatively assessed in terms of compaction characteristics and strength of fiber-reinforced BC soil. The present study indicated that the maximum dry density decreases with increase in percentage of coir fibers for both black cotton soils with and without optimum lime content. Marginal variation in maximum dry density (MDD) when fiber content is varied from 0 to 0.5% occurs and beyond 0.5% fiber content significant reduction in MDD occurs. Increasing fiber content increases the corresponding optimum moisture content (OMC) indicating addition of fiber increases water absorption by coir fibers causing an increase in OMC. However, the alkali treatment of coir fiber causes a significant reduction in water absorption leading to significant improvement in compaction characteristics and strength of BC soil.

Study on the Analysis of Mat Foundations Using a Different Approach

Mat foundations, in general, are reinforced concrete slabs to support and transfer structural load to the underlying soil, and are well suited to reduce differential settlement. Finite element (FE) method is widely used in the analysis, however the approach to solve and analyze the problem is of prime importance considering the engineering significance and cost involved in the structure. The main objective of this study was to analyze an idealized mat foundation soil system with different approach, which include the Mat foundation analyzed as an inverted flat slab by flat plate analysis and finite element analysis. The moment in longitudinal and transverse direction was determined from the analysis performed for models with two different KS of 4250kN/m 2 /m and 7250kN/m 2 /m. The results from flat plate analysis were similar to FE analysis, where direct design method overestimate the moment but certainly gives a more safe design when compared with the FE methods.

Revisiting seismic hazard assessment for Peninsular Malaysia using deterministic and probabilistic approaches

Seismic hazard assessments, both deterministic and probabilistic, for Peninsular Malaysia have been carried out using peak ground acceleration (PGA) data recorded between 2004 and 2016 by the Malaysian Meteorological Department using triaxial accelerometers placed at 19 seismic stations on the peninsula. Seismicity source modelling for the deterministic seismic hazard assessment (DSHA) used historical point sources whereas in the probabilistic (PSHA) approach, line and areal sources were used. The earthquake sources comprised the Sumatran subduction zone (SSZ), Sumatran fault zone (SFZ) and local intraplate (LI) faults. Gutenberg–Richter law b value for the various zones identified within the SSZ ranged between 0.56 and 1.06 (mean= 0.82) and for the zones within the SFZ, between 0.57 and 1.03 (mean= 0.89). Suitable ground motion prediction equations (GMPEs) for Peninsular Malaysia along with other pertinent information were used for constructing a logic tree for PSHA of the region. The DSHA “critical-worst” scenario suggests PGAs of 0.07–0.80 ms−2 (0.7–8.2 percent g), whilst the PSHA suggests mean PGAs of 0.11–0.55 ms−2 (0.5–5.4 percent g) and 0.20–1.02 ms−2 (1.9–10.1 percent g) at 10 % and 2 % probability of exceedance in 50 years, respectively. DSHA and PSHA, despite using different source models and methodologies, both conclude that the centralwestern cities of Peninsular Malaysia, located between 2 and 4 N, are most susceptible to high PGAs, due to neighbouring active Sumatran sources, SFZ and SSZ. Of the two Sumatran sources, surprisingly, the relatively less active SFZ source with low magnitude seismicity appeared as the major contributor due to its proximity. However, potential hazards due to SSZ mega-earthquakes should not be dismissed. Finally, DSHA performed using the limited LI seismic data from the Bukit Tinggi fault at a reasonable moment magnitude (Mw) value of 5.0 predicted a PGA of ∼ 0.40 ms−2 at Kuala Lumpur.

Data analytic engineering and its application in earthquake engineering: An overview

This paper deliberates the challenges of using regression models for earthquake data analysis and compares them with the field measurements. Regression analyses to model the peak ground acceleration (PGA) data are discussed with magnitude and distance as variables. Suitability of the models are further compared with the ground motion (PGA) field records obtained from the seismic stations within the peninsular Malaysia. Far field (distance above 300km from the epicenter) and local earthquakes within 50-300km with a wide range of moment magnitude (1.0-9.1) are considered in this study. Result from the regression models showed significant error between the predicted and field data. Further discussion highlights that the ground motion prediction equation (GMPE) is a function of multiple variables developed from the specific site properties. The paper concludes with a note showing the significance of statistical input and analysis in the GMPEs to achieve a more realistic earthquake data prediction model.