Comparison of Deflection Patterns of Simply Supported and Fixed Supported Beam Structures

When designing a building, the most of the important component is the roof. The selection of roofs for building depends on factors like type of building, type of foundation, roofing materials, roof loads, the climate, economy, the availability of materials, and the ease of construction. This study is focused on gable roof structures with two different supported structures of the ridge beam which are known as simply supported ridge beam structure and fixed supported ridge beam structure. The simply supported structure can be defined as the ends of the ridge beam are formed to stand freely on supports and the fixed supported structure can be defined as the ends of the ridge beam are supported to restrain against rotation and vertical movement. The study is considered jack wood beams which have the same length as 198 inches (5.03m) but have different cross-sectional area; 2x4inch2, 2x5inch2, 2x6inch2, 3x4inch2, 3x5inch2 and 3x6inch2. Further 11 Jack wood rafters which have the length 144 inches (3.66m) and cross sectional surface area 2x3 inch2 are used. Two Jack wood king post trusses that have kingposts with the length 30 inches (0.7m) are used for fixed supported structure to fix the beam between two supporters. The roof pitch angle is approximately 300. According to general fact, the deflection value of simply supported beam is higher than the deflection value of fixed supported beam. In this study, an attempt will be made to investigate the deformation of the ridge beam when it is simply supported and fixed supported and from that observe the optimum supported structure that can be used to design a roof of a building more constructive manner. Moreover by using the results, the validity of the general fact can be also proved. The major mathematical part in this study is to generate the model to calculate deflection of the ridge beam when it is simply and fixed supported by using Euler-Bernoulli Beam theory and Fourier series. The results showed that the deflection value of simply supported beam around 0.8-0.04 m and thedeflection value of fixed supported beam around 0.008-0.001 m. According to results, the study was confirmed the general fact of the deflection values of simply supported beam structure has higher than fixed supported beam structure

A Comparative Study on Socio-Economic Impact of COVID- 19 Pandemic on Fisheries Industry in Tangalle Divisional Secretariat Division

The COVID-19 pandemic, which has provided the basis for creating a highly problematic environment in every sector of the world today has also had a significant impact on the fisheries industry which is one of the world’s leading economic activities. The main objective of this study was to examine the socio-economic impacts on fisheries industry before and during COVID-19 pandemic situation with special reference to Tangalle Divisional Secretariat Division. The study was based on the four Grama Niladhari Divisions of Kudawella North, Central, South and West associated with the Kudawella Fisheries Harbor. Primary data was collected from a field survey using a semi structured questionnaire from 74 fishing families representing the 75% of the population under stratified random sampling. Paired T test was carried out to test the variables comparatively before and after COVID-19 pandemic to confirm the result statistically. In addition, simple statistical methods were used for the quantitative assessment. Results revealed that the epidemic situation had a significant socio-economic impact on the fishing industry during the COVID-19 pandemic situation such as declining income, growth of indebtedness, disruption of children’s education, mental distress and social stigma. Suggestions were identified to mitigate the impacts. In this context, it was concluded that the COVID-19 epidemic has primarily affected the fisheries industry and as a result, created many socio-economic problems for the fisheries community. DOI: http://doi.org/10.31357/fhss/vjhss.v07i01.0

Structural basis for Clostridium perfringens enterotoxin targeting of claudins at tight junctions in mammalian gut

The bacterium Clostridium perfringens causes severe, sometimes lethal gastrointestinal disorders in humans, including enteritis and enterotoxemia. Type F strains produce an enterotoxin (CpE) that causes the third most common foodborne illness in the United States. CpE induces gut breakdown by disrupting barriers at cell–cell contacts called tight junctions (TJs), which are formed and maintained by claudins. Targeted binding of CpE to specific claudins, encoded by its C-terminal domain (cCpE), loosens TJ barriers to trigger molecular leaks between cells. Cytotoxicity results from claudin-bound CpE complexes forming pores in cell membranes. In mammalian tissues, 24 claudins govern TJ barriers—but the basis for CpE’s selective targeting of claudins in the gut was undetermined. We report the structure of human claudin-4 in complex with cCpE, which reveals that entero-toxin targets a motif conserved in receptive claudins and how the motif imparts high-affinity CpE binding to these but not other sub-types. The structural basis of CpE targeting is supported by binding affinities, kinetics, and half-lives of claudin–enterotoxin complexes and by the cytotoxic effects of CpE on claudin-expressing cells. By correlating the binding residence times of claudin–CpE complexes we determined to claudin expression patterns in the gut, we uncover that the primary CpE receptors differ in mice and humans due to sequence changes in the target motif. These findings provide the molecular and structural element CpE employs for subtype-specific targeting of claudins during pathogenicity of C. perfringens in the gut and a framework for new strategies to treat CpE-based illnesses in domesticated mammals and humans

Effect of submerged and floating plants on dissolved oxygen dynamics and nitrogen removal in constructed wetlands

Dissolved oxygen (DO) concentration affects the treatment processes in constructed wetlands. This study examined the dissolved oxygen dynamics and total nitrogen removal in constructed wetlands with submerged and floating plants. Four constructed wetland units each with the surface area of 3 x 1 m2 were constructed at University of Peradeniya. Two of those with the depths of 0.3 m (A) and 0.6 m (B) were planted separately with Hydrilla verticillata (submerged) and Lemna minor (floating), respectively. Other two (C and D) were constructed with two sections of 0.3 and 0.6 m depths and planted with H. verticillata and L. minor, respectively in each section. Secondary effluent from student hostel was fed with hydraulic retention time of 6 days. DO was measured at different depths of water, 0.0, 0.1, 0.2, 0.4 and 0.5 m from the water surface and along the longitudinal axis of the wetland at 6 hours interval. The total nitrogen was measured for water samples at inlet and outlets. The average dissolved oxygen concentrations of A and B were 17.7 and 0.4 mg L-1 respectively. Oxic condition was maintained in the submerged plant units. Anoxic condition resulted throughout the day in floating plant system. DO varied significantly with depths in oxic condition. DO dynamics in these wetlands can be explained by photosynthesis,respiration, deaeration and reaeration processes. The highest total nitrogen removal was achieved in unit D where combined anoxic and oxic conditions were maintained together H.verticillata and L. minor could effectively be used to maintain required dissolved oxygen in constructed wetlands for nitrate removal

Structural basis for Clostridium perfringens enterotoxin targeting of claudins at tight junctions in mammalian gut.

The bacterium Clostridium perfringens causes severe, sometimes lethal gastrointestinal disorders in humans, including enteritis and enterotoxemia. Type F strains produce an enterotoxin (CpE) that causes the third most common foodborne illness in the United States. CpE induces gut breakdown by disrupting barriers at cell-cell contacts called tight junctions (TJs), which are formed and maintained by claudins. Targeted binding of CpE to specific claudins, encoded by its C-terminal domain (cCpE), loosens TJ barriers to trigger molecular leaks between cells. Cytotoxicity results from claudin-bound CpE complexes forming pores in cell membranes. In mammalian tissues, ∼24 claudins govern TJ barriers-but the basis for CpE's selective targeting of claudins in the gut was undetermined. We report the structure of human claudin-4 in complex with cCpE, which reveals that enterotoxin targets a motif conserved in receptive claudins and how the motif imparts high-affinity CpE binding to these but not other subtypes. The structural basis of CpE targeting is supported by binding affinities, kinetics, and half-lives of claudin-enterotoxin complexes and by the cytotoxic effects of CpE on claudin-expressing cells. By correlating the binding residence times of claudin-CpE complexes we determined to claudin expression patterns in the gut, we uncover that the primary CpE receptors differ in mice and humans due to sequence changes in the target motif. These findings provide the molecular and structural element CpE employs for subtype-specific targeting of claudins during pathogenicity of C. perfringens in the gut and a framework for new strategies to treat CpE-based illnesses in domesticated mammals and humans

Performance evaluation of coconut coir-pith in free water surface constructed wetlands.

A study on wastewater treatment with a submergent wetland system was conducted at the University of Peradeniya, Sri Lanka. The primary objective of this study was to identify the improved potential for wastewater purification due to surplus organic carbon on microbiological activities and adsorption by coconut (Cocos nucifera) coir-pith as an alternative substrate material. Three constructed wetland units (Lysimeters-L1, L2 and L3) were used in the study, each having the dimensions of 5 m, 1 m and 0.6 m in length, width and depth, respectively. The substrate layer of each Lysimeter was amended with coconut coir pith and river sand as 100% river sand (L1), 100% coir-pith (L3) and mixture of then in equal compositions (L2,v/v=1:1). Hydrilla verticillata was planted in each Lysimeter with equal plant density. Influent and effluent water samples were analyzed for pH, conductivity, total suspended solids (TSS), total dissolved solids (TDS), five-day biochemical oxygen demand (BOD5), total nitrogen (TN), ammonia nitrogen (NH4N), and nitrate nitrogen (NO3-N), phosphate phosphorous (PO4-P) and faecal coliform bacteria in weekly interval. A parallel study was conducted at the laboratory in order to examine the best ratio of sand: coir-pith for the growth of H. verticillata. The removal efficiency of NH4-N, PO4-P, BOD5, Total coliform and TSS in L2, were 93%, 74%, 54%, 93% and 62%, respectively, which were higher than the other two Lysimeters (L1 and L3). The results of effluent water quality analysis illustrated that the coir- pith is efficient in removing nutrients from wastewater over sand. The laboratory experiment revealed that the coir and river sand mixture in equal compositions provides the best substrate media for plant growth

Risk of soil and water pollution by heavy metals in landfill leachate.

Environmental pollution due to landfill leachate has been studied extensively for inorganic and organic pollutants. This study investigates the risk of soil and water pollution by heavy metals in leachate from a selected landfill in Gampola, Sri Lanka. Leachate and soils from the landfill were collected and analyzed for heavy metals. The results reveal that the heavy metal concentrations in leachate is relatively low and highest quality rating scales of 620, 108 and 74 % were resulted for Cd, Pb and Cr, respectively. Heavy metal concentrations in soils were higher than that of leachate and showed a decreasing trend with increasing distance from the landfill. The highest content of Cd, Mn and Cu were 21,173 and 2493 mg kg-1, respectively at the landfill whereas highest content of Zn, Ni, Pb and Cr (1619, 76, 1003 and 239 mg kg-1, respectively) was found within 1 m distance from the dumpsite. Interestingly, Lead, Cadmium, Copper and Zinc were exceeded the Sri Lankan standards limits of heavy metals for compost. Moreover, heavy metals in soil samples showed higher concentrations than concentrations in leachate. The concentrations of 0.038, 0.14 and 0.037 mg L-1 were resulted for Cd, Pb and Cr, respectively in landfill leachate. It can be concluded that the soils are highly contaminated with heavy metals from landfill leachate indicating the potential of the soils to be a natural attenuating agent. However, when the soils’ capacity exceeds there is a possibility of ground and surface water contaminations by heavy metals in landfill leachate

Characterization of aqueous Pb(II) and Cd(II) biosorption on native and chemically modified Alstonia macrophylla saw dust

This study was conducted inorder to understand the mechanism of Cd and Pb adsorption in aqueous solutions by raw and modified saw dust (SD) of Alstoniamacrophylla. The biosorbent was characterized by Boehm titration, specific surface area, scanning electron microscopy (SEM), X-ray energy dispersion (EDAX), and Fourier transform infrared (FTIR) analyses. SD was treated using organic acids and bases. Batch studies were conducted for raw and modified SD to determine the effect of initial concentration, pH, ionic strength, and contact time on metal adsorption. The specific surface area and total basic and acidic groups of SD were 77 m2/g and 1521 and 2312 µmol/g, respectively. The adsorption of both metals onto SD was pH dependent. No ionic strength dependency was observed in adsorption of Cd and Pb at pH >6, indicating inner sphere surface complexation. Monolayer adsorption is dominant in both metal sorptions by SD. Furthermore, there is no competition between metals on adsorption and raw SD was found to be suitable for removal of Cd and Pb as compared to organic acid– or base-treated SD. Maximum adsorption capacity of SD for Cd and Pb were 30.6 and 204.2 mg/g, respectively. Results indicate that the A.macrophylla SD can be considered as a potential material for metal ion removal from wastewater