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Biology of plumeria leaf rust disease caused by coleosporium plumeriae
(University of Peradeniya, 2006) Weeraratne, T. P.; Adikaram, N. K. B.
The leaf rust disease in Plumeria first appeared in Sri Lanka some time in the year 2002 and is now widespread. The disease is found in both Plumeria rubra and P. obtusa (Apocynaceae) and the infected leaves show numerous tiny, raised, orange, rusty pustules on the abaxial surface of the leaf. The adaxial surface opposite to infected sites is chlorotic reducing the available photosynthetic area of the leaf. Symptoms were absent in the stem or flowers. The causal agent was identified as Coleosporium plumeriae. This is the first report of Plumeria leaf rust in Sri Lanka. Microscopic studies indicated the presence of uredia, formed from the transversing mycelium and emerged through ruptured lower epidermis. No other fruiting structures, telium, aecium or spermatium were encountered at any stage of the disease in Plumeria or in Pinus, which was previously reported as a secondary host of C. plumeriae. Two other fungi, Absidia sp. and Verticillium sp., were found to colonize the rust areas of more mature leaves in succession, Absidia sp. appearing first. These two fungi grew as mycoparasites on C. plumeriae and had no direct contact with the leaf tissue. However, colonization by these two fungi resulted in necrosis around the rust infections inflicting damage to leaves. Young leaves down to about the third from the apical bud are resistant to rust infection. Young leaves contain more latex compared to mature leaves and the latex shows inhibitory action against germination of uredospores. Latex was found to possess chitinase activity on a gel diffusion assay. Latex may therefore be playing a role in the resistance of young leaves against rust infection.
Influence of Trichoderma Harzianum Metabolites on the development of Green Mould Disease in the Oyster Mushroom
(University of Peradeniya, 2007) Jayalal, R. G. U.; Adikaram, N. K. B.
Green mould disease in Oyster mushroom (Pleurotus ostreatus) caused by Trichoderma harzianum results in considerable inhibition of growth of mycelium and fruit bodies of Oyster mushroom lowering the yield substantially. The study examined how mushroom growth is inhibited while T. harzianum growth is accelerated. Diseased mushroom bags were collected from mushroom houses within the Kandy district and T. harzianum was isolated. The most dominant strain was identified as T. harzianum biotype II (Th 2) from the colony and growth characteristics. When the two fungi were grown on dual culture, T. harzianum overgrew the colonies of P. ostreatus rapidly. Diffusible metabolites produced by T. harzianum in culture significantly reduced the growth of P. ostreatus. Volatile metabolites of T. harzianum slightly stimulated the mycelial growth of P. ostreatus initially but P. ostreatus soon reverted to its normal growth. Growth of T. harzianum was not stimulated by P. ostreatus metabolites. Understanding of the metabolic interactions between the two organisms may be useful for developing measures that counter the inhibitory effect of T. harzianum metabolites on mushroom growth and overcome green mould growth
Occurrence of Leaf Blotch Disease (Botryosphaeria sp. ) in Ficus religiosa in Sri Lanka
(University of Peradeniya, 2009) Maharachchikumbura, S. S. N.; Adikaram, N. K. B.
This paper reports the occurrence of a leaf blotch disease in Ficus religiosa in Sri Lanka. The disease first appears as small, irregular, yellow specks in leaves at later stages of maturity and with time the infected areas become necrotic and gradually enlarge. At advanced stages the whole leaf turns yellow with brown blotches and is shed. The causal agent was identified as Botryosphaeria sp. The necrotic blotches are associated with erumpent fruiting bodies of the fungus, ascomata. Ascomata are solitary or botryose and are found on both sides of leaves. Asci are with numerous pseudoparaphyses and ascospores were observed. Colony developed on water agar medium showed hyaline, aseptate conidia and mature brown conidia. In the presence of leaf blight caused by Glomerella cingulata, the leaf blotch symptoms appeared much later, about 10-12 weeks after the new flush. The diseased leaves do not last long as F. religiosa, being a deciduous species, sheds leaves seasonally. However, the fallen leaves, unless eliminated, may provide a good source of inoculum for infection of the new flush. Commercial fungicide, BULLET 50, inhibited the in vitro growth of Botryosphaeria sp. This is the first report on a blotch disease attacking leaves of F. religiosa in Sri Lanka.
A Phenetic analysis of Cllectotrichum Gloesporioides Isolates from Selected Host Plants
(University of Peradeniya, 2009) Gunawardhana, P. L. T.; Senevirathna, A. M. W. K.; Adikaram, N. K. B.; Yakandawala, D. M. D.
Colletotrichum gloeosporioides is a ubiquitous fungus which infects a wide variety of plants in tropical, sub-tropical and temperate regions. This fungus accounts for substantial economic losses through out the world via both preharvest and postharvest diseases. A phenetic analysis of C. gloeosporioides isolated from Capsicum frutescens, Carica papaya, Mangifera indica, Persea americana, Ficus religiosa and Hevea brasiliensis was carried out to identify sub-specific populations. A total of 40 isolates from these six host species were used. The overall similarity among different isolates of C. gloeosporioides was determined using culture, conidial and appressorial characteristics. According to the resulting phenogram, fungal isolates had divided into two distinct groups at the initial stage separating C. papaya isolates from the rest of the isolates. The subsequent branching has lead to separation of C. gloeosporioides isolates of different hosts into distinct groups. A high degree of similarity was observed among the isolates obtained from C. frutescens, H. brasiliensis and F. religiosa. Similarly, isolates of P. americana and M. indica appear to be morphologically more similar to each other. Further, the study confirms the cross infection potential of some C. gloeosporioides isolates and the presence of host specific populations.
Poisoning of 'Binthamburu' (Ipomoea asarifolia) due to Misidentificatiom as 'Kankun' (Ipomea aquatica)
(University of Peradeniya, 2010) Ratnatilaka, A.; Yakandawala, D.; Ratnayake, K.
Ingestion of ‘Binthamburu’ (Ipomoea asarifolia) by misidentification as ‘kankun’ (Ipomoea aquatica) as a leafy vegetable causes acute gastrointestinal symptoms and confusion. The authors have encountered four such cases in the past. All cases have been recorded from the dry zone of the country. Both plants are two trailing vines similar in their appearance and preferring the wet habitats. During the course of the day when exposed to sunlight, ‘binthamburu’ leaves mimic ‘kankun’ leaves by folding the leaf margins making it difficult to separate the two during harvest and only a closer examination will 1Medical Unit, Teaching Hospital Kurunegala, and 2Faculty of Science, University of Peradeniya, Sri Lanka. Correspondence: DY, e-mail . Received 11 August and accepted 17 November 2009. Competing interests: none declared reveal the difference in their leaf shapes. Ipomoea asarifolia toxicity in human has not been recorded but animal toxicity in North Brazil due to ingestion of Ipomoea asarifolia had been investigated and linked to a toxic substance identified as lectin or LTS.
Characterization of low Cost P-Cu2O/N-CUO Junction
(University of Peradeniya, 2010) Samarasekara, P.
Optical and electrical properties of thin film p-Cu2 O/n-CuO junction were investigated. It was found that such junction can be fabricated by controlled oxidation of copper films in 400-500 o C in different O2 and Ar partial pressures. Clear diode characteristics were observed at room temperature (25 o C) for the thin film device fabricated on transparent conductive glass substrates. The breakdown voltage and threshold voltages were -0.95 V and 0.75 V, respectively. Optical properties of Cu 2 O and CuO thin films clearly indicated that each film and their junction well agree with previously reported data.
Hybridization between native and invasive alien plants: an overlooked threat to the biodiversity of Sri Lanka
(University of Peradeniya, 2011) Yakandawala, D.; Yakandawala, K.
Conservation of native biological diversity is one of the major challenges of this century. Invasive alien species (IAS) are a part of this challenge because a small but a significant fraction of IAS contribute to the demise of native species. The present paper reviews current literature on the phenomenon of hybridization in plants supporting the evolution of invasiveness, which is identified as a major threat to the extinction of native species. Further, the phenomenon of hybridization is been reviewed on a Sri Lankan context by citing evidence from a preliminary study between the native Nymphaea nouchali and an introduced violet flowered water-lily that has got established in water-bodies of Sri Lanka. This violet flowered water-lily has been incorrectly identified as the native Nymphaea nouchali, the National flower of Sri Lanka (‘Nil Manel’). Revealing the flawed identity of the violet flowered Nymphaea, its hybrid origin and the hybridization with the native N. nouchali, provides an excellent opportunity for initiating studies on a novel area in hybridization between natives and invasive alien species of plants in Sri Lanka.
Allelopathic activity studies of Sri Lankan flora and chemical investigation of endophytic fungi and terrestrial STREPTOMYCES species
(University of Peradeniya, 2011) Piyasena, K. G. N. P.
he first part of the present investigation is focused on the search for the allelopathic active compounds from Sri Lankan plants, with the hope of using them as herbicides. In order to trace allelopathic activity, seed germination inhibition bioassay was employed, using lettuce (Lactuca sativa) and barnyard grass (Echinochloa crus-gall) seeds. Out of 60 plant extracts tested, 14 plant extracts significantly reduced radicle growth of lettuce seeds and bamyard grass seeds. Considering preliminary activity results, the ariel parts of Mikania scandens and the bark of Canarium zeylanicum were selected for further chemical and biological investigation, with the aim of isolating allelochemicals, which are responsible for the above activity. Activity guided fractionation of the M. scandens extract led to the isolation of highly active compound mikanolide which showed lettuce seed inhibition activity at MIC 25.0 pg/mL. Activity guided fractionation of the C. zeylanicum bark extract led to the isolation of two compounds 13- hydroxy-12-methoxy-8, 1 1,13-podocarpatrien-3-one and 38-OAc,28-COOH acetyl aleuritolic acid. As M_ scandens is a highly abundant invasive plant in Sri Lanka, either this plant in crude form or as mikanolide in pure form could be developed as an environmental friendly herbicides in Sri Lanka. The second part of the present study was focused on chemical investigation of endophytic microorganisms, especially fungi and terrestrial Streptomyces, with the aim of isolating biologically active compounds. In this process, isolated fungi were cultivated, extracted, and tested for biological activities. According to the chemical and biological screening nine endophytic fungal strains and three terrestrial Streptomyces strains were selected for further chemical investigation. From these strains, seventy compounds were isolated using chromatographic techniques. Of them seven compounds were found to be new. They are hydroxy-2-isocyanatebenzoic acid, 2-isocyanate-3-methoxy-benzoic acid, 5,6-dimethyl-2, 3- dihydro-phthalazine-1,4-dione, tectariamide, 1,3,5,7-tetraaza-tricyclo[6.6.1.0*4,15*]pentade ca- 2,4 (15),5,7-tetraene, 2-phenyl-2H-pyrazolo[3,4-d] pyrimidine and N-(chloro-1, 3, 4, 5, 6- pentahydroxyl-hexyl)acetamide. Structural elucidation of the new compounds and other isolates were carried out with the help spectroscopic analysis, x-ray analysis, comparison with literature data and the help of AntiBase data base. Antibacterial activity of above compounds was tested against five control strains FE. coli (ATCC25922), Pseudomonas aeruginosa (ATCC27853), Enterococci faecalis (ATCC 29212), Bacillus subtilis (ATCC6051), Streptomyces viridochromogenes (Ti 57) and Staphylococcus aureus (ATCC29213) using a disk diffusion method (40 yg/disk). Of them, cercosporamide, beauvericin and altertoxin I showed the highest activity against Bacillus subtilis and E. coli. Antifungal activity of isolates were tested against strains of human pathogenic fungus Candida albicans and plant pathogenic fungi Rhizoctonia solani and Pythium ultimum, using disk diffusion method. Glaucanic acid and beauvericin showed the highest activity against Candida albicans. Algaecide activity of isolates was tested against strains of three microalgae; Chlorellavulgaris, Chlorella sorokiniana, and Scenedesmus subspicatus were used in this study. Of them, only julichrome Q3,3 showed activity against Chlorella vulgaris.
Discovery of a Novel Ferrielectric subphase of Five-Laye Periodicity in Binary Mixtures of Chiral Smetic Reversed Phase Sequence
(University of Pearadeniya, 2011) Chandani, A. D. L.; Fukuda, Atsuo; Kumar, S.; Jagdish, K. Vij
In a binary mixture system of ferroelectric and antiferroelectric liquid crystals whose major component shows an unusual reversed phase sequence of SmC∗A(1/2)−SmC∗, a new phase with ferrielectric order of five layers has been discovered by the electric field-induced birefringence (EFIB) measurements. The EFIB was measured using a photo-elastic modulator (PEM) set-up and by applying an in-plane electric field to a homeotropic aligned cell filled with the binary mixtures of compounds with ferroelectric and antiferroelectric compounds. The contours of constant birefringence in the electric field–temperature (E–T) phase diagrams clearly indicate a distinct region corresponding to a new phase bordering the four-layer SmC∗(1/2) on the low temperature side and SmC∗α on the high temperature side. This new phase is unambiguously assigned to SmC∗(3/5) whose structure has been calculated by Osipov and Gorkunov.
Denture Induced Stomatitis and Associated Factors in Patients Attending the Dental Hospital, Peradeniya, Sri Lanka
(University of Peradeniya, 2011-11-24) Thilakumara, I. P; Jayasoonya, P. R; Jayatilake, J. A. M. S; Abeypala, G. A. K. K; Liyanage, R .L. P. R; Pallegama, R. W
Denture induced stomatitis (DIS) is a common oral medical problem in the elderly denture wearers. Clinically, DIS is characterized by erythematic patches on the denture bearing mucosa in both jaws with a high predilection for maxilla. However, there is no consensus on the aetiological factors of DIS at present. Therefore, objectives of this study were to determine the factors associated with DIS, assess the feasibility of using the presence of hyphae in palatal smears and denture surfaces to diagnose Candida associated DIS and assess the oral and hand carriage of Candida by DIS patients. Complete or Partial denture wearers (n=47) presented to the clinic with DIS from April to September 2011 were included in the study. An interviewer administered questionnaire was used to obtain socio-demographic data, medical and dental history, status of receiving post delivery instructions and denture and oral hygiene habits. Denture hygiene was assessed using modified Hoad-Reddic classification. Clinical type of DIS was recorded in Newton's classification. A scraping from the palatal mucosa and a swab from the denture surface were obtained from each patient and stained with PeriodiC Acid Schiff stain to determine the presence of candidal hyphae. Concentrated oral rinse technique using 10 ml of sterile phosphate buffered saline was done in order to assess the oral yeast colonisation. Candidal hand carriage was assessed using fingerprints on a plate of Sabourad's agar. Identification of Candida was done using colony characteristics and Gram's stain. There were 87.2% (n=41) Sinhalese, 6.4% (n=3) Tamils and 6.3% (n=3) Moors, out of which 89.4% (n=42) were female and 10.6% (n=5) were males. Their ages ranged from 31-80 years (mean = 56.91; SO = 10.07). Eighty three percent had received post delivery instructions. Unsatisfactory denture hygiene was observed in 70.2% of the upper dentures. Majority (66.0%) used dentures during sleep. Age of the current denture set varied from 1-41 years (Median = 10; Interquartile Range = 5-17). Most frequent clinical pattern of DIS was Newton type II (70.2%). Majority (57.7%) showed candidal hyphae on both palatal mucosa and denture. There were 55.3% (n=26) patients carrying Candida in oral cavity and in hands. The odds ratio for carrying Candida in hand by oral candidal carriers was 9.5. Our observations are in agreement with a previous finding. The likelihood of carrying Candida in hand by an oral candidal carrier was very high. Factors such as denture hygiene, increased denture age and use during sleep may be associated with DIS. Denture hygiene was generally not satisfactory in majority in spite of high rate of receiving post delivery instructions.
Denture induced stomatitis and associated factors in patients attending the Dental Hospital, Peradeniya, Sri Lanka
(University of Peradeniya, 2011-11-24) Thilakumara, I. P; Jayasoonya, P. R; Jayatilake, J. A. M. S; Abeypala, G. A. K. K; Liyanage, R .L. P. R; Pallegama, R. W
Denture induced stomatitis (DIS) is a common oral medical problem in the elderly denture wearers. Clinically, DIS is characterized by erythematic patches on the denture bearing mucosa in both jaws with a high predilection for maxilla. However, there is no consensus on the aetiological factors of DIS at present. Therefore, objectives of this study were to determine the factors associated with DIS, assess the feasibility of using the presence of hyphae in palatal smears and denture surfaces to diagnose Candida associated DIS and assess the oral and hand carriage of Candida by DIS patients. Complete or Partial denture wearers (n=47) presented to the clinic with DIS from April to September 2011 were included in the study. An interviewer administered questionnaire was used to obtain socio-demographic data, medical and dental history, status of receiving post delivery instructions and denture and oral hygiene habits. Denture hygiene was assessed using modified Hoad-Reddic classification. Clinical type of DIS was recorded in Newton's classification. A scraping from the palatal mucosa and a swab from the denture surface were obtained from each patient and stained with PeriodiC Acid Schiff stain to determine the presence of candidal hyphae. Concentrated oral rinse technique using 10 ml of sterile phosphate buffered saline was done in order to assess the oral yeast colonisation. Candidal hand carriage was assessed using fingerprints on a plate of Sabourad's agar. Identification of Candida was done using colony characteristics and Gram's stain. There were 87.2% (n=41) Sinhalese, 6.4% (n=3) Tamils and 6.3% (n=3) Moors, out of which 89.4% (n=42) were female and 10.6% (n=5) were males. Their ages ranged from 31-80 years (mean = 56.91; SO = 10.07). Eighty three percent had received post delivery instructions. Unsatisfactory denture hygiene was observed in 70.2% of the upper dentures. Majority (66.0%) used dentures during sleep. Age of the current denture set varied from 1-41 years (Median = 10; Interquartile Range = 5-17). Most frequent clinical pattern of DIS was Newton type II (70.2%). Majority (57.7%) showed candidal hyphae on both palatal mucosa and denture. There were 55.3% (n=26) patients carrying Candida in oral cavity and in hands. The odds ratio for carrying Candida in hand by oral candidal carriers was 9.5. Our observations are in agreement with a previous finding. The likelihood of carrying Candida in hand by an oral candidal carrier was very high. Factors such as denture hygiene, increased denture age and use during sleep may be associated with DIS. Denture hygiene was generally not satisfactory in majority in spite of high rate of receiving post delivery instructions.
Information on Meteorological Observatories in Sri Lanka
(University of Peradeniya, 2011-11-24) Rekha Nianthi, K. W. G
The systematic official Meteorological station network of Sri Lanka was established in 1865. At present there are 22 main Meteorological Observatories, 38 Agro- Meteorological stations, 35 Automatic Weather Stations (AWS) including some main Meteorological Observatories, and more than 500 rain-gauges maintained by the Colombo main Meteorology Department, various Governmental Organizations (GOs) and Non Governmental Organizations (NGOs) across the country. Many university researchers obtain climatic data from the above stations for conducting climate-related studies on Sri Lanka. The Department of Geography of the University of Peradeniya offers climate related courses for undergraduates as well as postgraduates. It is very important to obtain accurate and up-to-date climatic data (period of the climate data availability, type of climatic parameters and the observation areas) for these purposes. As there is no proper climatic data information available even in the Meteorology Department at Colombo, obtaining up-to-date climatic parameters is very difficult for students as well as staff at the University of Peradeniya when they carry out climatic studies. Therefore, the main objective of this study was to make a small pamphlet of climatic observations based on the data collected from various reports, websites, field observations, and discussions with relevant officers of the observation stations. Based on this information, and up-to date information pamphlet was prepared, fulfilling the main objectives of this project. The prepared pamphlets will be used as teaching material for the relevant courses at the Department of Geography. Copies of the pamphlet will be distributed free of charge to Geography students, some selected Meteorological Observatories visited by the author, Main Library of the University of Peradeniya, library of the Geography Department, and researchers at the University of Peradeniya and other institutions who require this information. This information could be up-dated by the author regularly.
Eye Gaze Direction for Human-Computer Interaction
(University of Peradeniya, 2011-11-24) Gunarathne, M; Bandara, R; Elkaduwe, D; Ragel, R
Human Computer Interaction (HCI) is a technique used for interaction between users and computing systems which occurs through user interfaces (including both hardware and software) of a computing system. Hel devices can generally be divided into two: the input peripherals and the output peripherals. The objective of this study is to describe a new technique for the former. Although new Hel techniques and devices are being introduced and deployed in computing systems for input peripherals (from different types of keyboards to mice and touch screens), they essentially failed to address the problems encountered by a group of users who have difficulties (such as disabilities due to accidents, aging, etc.) in using their hands for handling such devices. Thus, the present research focuses on enabling the disabled to use computing systems through a new Hel technique, namely, eye gaze direction (i.e., a steady, fixed look; or simply, 'where we are looking'). 121 As technology evolves rapidly, all individuals should benefit, irrespective of whether they are disabled or not. Unfortunately, a disabled person, who does not have the ability to move his I her hands (due to spinal cord injuries, brain injuries, multiple sclerosis, strokes, etc.), cannot use a typical computer due to inability in moving the mouse. Therefore, we propose to use eye-gaze direction as an input method to the computer. In such a setup, the eye-gaze direction of the user will be detected by an eye-gaze direction monitor, used as input to the computer. This will be useful not only for disabled persons, but as an alternative input method in environments such as gaming consoles. We built a low-cost, nonintrusive system which can be used to move the mouse pointer through eye-gaze direction and perform mouse-actions. To achieve these goals, typical eye-gaze tracking systems use methods such as optics, electronics, mechanics, etc. In our system, we used a mounted camera (a low cost webcam) in front of the user to capture the images, which are then sent to the computer. The computer processes these images and determines the eye gaze direction and tgestures necessary to control mouse- actions such as single-clicking, double-clicking and zooming. Although a few similar systems exist, they are very expensive (as they use special-purpose eye-gaze direction trackers, such as a high priced camera) and have limited functionalities. There are obstacles when designing and implementing eye-gaze tracking systems due to trade-offs between requirements. The major challenges of such a system; ensuring smooth movement of the mouse pointer as the eye-gaze direction changes and real-time responsiveness of the system; were overcome in our project. We overcame drawbacks in the existing eye-gaze tracking systems by enhancing accuracy of the eye- gaze direction detection and by improving the efficiency of the existing algorithms. Effective image processing techniques and haar-like features were used to achieve our final goal, which is to help the disabled to cope with and to utilise the latest technologies
PCR·SSCP Polymorphism of BMP4 Gene (Intron II) in goats in Damana and Thirukkovil Veterinary service divisions in the Ampara District of Sri Lanka
(University of Peradeniya, 2011-11-24) Lokugalappatti, L. G. S; Wijesena, H. R; Munasinghe, D. M. S; Gunawardena, D. C. A; Ariyaratne, H. B.S
Application of molecular genetic approaches for screening of economically important quantitative traits (i.e. growth and reproduction) in goats is an effective way of increasing their productivity through improved selection based on genetic markers. Single Strand Confirmation Polymorphism (SSCP) analysis is one such powerful. genetic screening method to identify the sequence variation in Polymerase Chain Reaction (PCR) amplified DNA. In the present preliminary study, we investigated genetic variation in the second intron of bone morphogenetic protein 4 (BMP4) gene, by PCR-SSCP, in local indigenous (LI) and Jamnapari crossbred (JC) goats in Damana and Thirukkovil Veterinary Service (VS) divisions in the Ampara district. Genomic DNA was extracted from a total of 103 samples (49 LI and 54 JC) collected from 15 farms located in the two VS divisions and subjected to PCR-SSCP analysis. Polymorphism was detected in both LI and JC goats of the study area and five different conformational patterns were identified (A through E). Three conformational patterns (A, B and C) were found in both LI and JC animals. Patterns D and E were unique to LI animals, indicating the benefit of searching for more genetic markers. Calculated total frequencies of patterns A, B, C, D and E as revealed by PCR-SSCP were 58.25%, 14.56%, 5.83%, 11.65% and 9.71 % respectively. In general, pattern A was predominantly found in both LI (40.43%) and JC (73.21%) whereas pattern C was found to be at lowest frequency in both groups. Pattern D observed in LI goats may have some association with phenotype and growth of the animals as we observed similar external characters in all the animals possessing pattern D. Gene sequencing of the five conformational patterns observed are being pursued to identify the genotypes and the alleles present.
Low Carbon cooling solutions for the apparel industry: open cycle desiccant cooling systems
(University of Peradeniya, 2011-11-24) Bakmeedeniya, L. U; Rajapaksha, L
Use of mechanical ventilation and air conditioning is becoming more prevalent in commercial and industrial sectors due to warm and humid outdoor conditions in most parts of the country. Such change in the use of energy for comfort is further supported by the requirements for clean air in working environments specified in relevant health and safety regulations. The common practice in maintaining required relatively comfortable indoor conditions is to use mechanical ventilation plus conditioning of air using conventional vapour compression refrigeration. Undesirable aspects of this technology are the use of environmentally harmful refrigerants and use of electricity that in many cases add a substantial running electricity bill. A more sustainable and low carbon alternative to vapour compression refrigeration based air conditioning would be to consider technologies that incorporate natural phenomena of cooling that use low-grade energy from industries or any other renewable source. Here, an evaporation and regeneration-based desiccant cooling system provide a satisfactory alternative for applications where indoor conditions are not very closely controlled. This paper presents a study of a desiccant cooling system. The analysis is based on a software tool; TRNSYS, which enables detailed modelling of the heat and mass transfer process in a desiccant system, particularly the regeneration process and heat/ mass transfer process in desiccant wheel. The performance of a cooling solution is parametrically studied, where the regeneration energy to drive the cooling cycle is determined by examining the humidity ratio and temperature profiles for a year on an hourly basis. The results of the simulations, at different conditions, in an air dehumidifier, are used to propose an optimum coefficient of performance (COP) of the cooling system for a selected case study. Comfort indoor conditions specified in ASHRAE standards, i.e., of 25°C dry bulb temperature and 50% relative humidity were considered in the simulations as the desired indoor conditions. The results indicate that hot water storage at 100°C via a heat exchanger can produce the thermal energy required to heat up the return air at 70°C to regenerate the desiccant. The ventilation air flow rate is maintained at 20,000 kg/hr while the hot water flow rate required to produce the necessary energy of 250 kW is 1.2 kg/so The cooling load met by the system is 120 kW and the calculated coefficient of performance of the desiccant cooling system is 0.48, which saves up to 40% in current electrical energy use of the application concerned. This study makes it clear that use of low grade heat or renewable sources to drive the thermally activated component of a desiccant system have a number of benefits including reduction of peak demand and less energy consumption; i.e., a low carbon footprints. This work shows that a desiccant cooling concept could maintain satisfactory indoor conditions at a lower energy consumption level and presents a sustainable alternative to supplement industrial space cooling demands.
Migrant Wife and Househusband: Transformation of Household Gender Roles with Female Migration
(University of Peradeniya, 2011-11-24) Pinnawala, M
Traditionally the woman's place of "work" has been confined to the so-called private sphere, namely, the household. In the household, she was expected to perform traditional womens' work such as looking after the children, washing, cooking, etc. The husband was the provider of the family and his tasks were almost exclusively in the public sphere. Many women today have become providers, sometimes even as sole income earners of the family. One modern context in which this traditional division of gender roles comes into question is when woman become independent migrants requiring husbands to takeover traditional household tasks. Research shows that this has often resulted in displacing the husband from the traditional role of the sole decision maker in migrant households. These changes are challenging the traditional pattern of male-dominated household organization and have resulted in emergence of a new phenomenon described as migrant-wife or househusband. This paper examines how the changing of the traditional role of the wife affects the husband's traditional role in the households of Sri Lankan women who are working in the Middle East as housemaids. ' The study was conducted in a migrant source community in the district of Kurunagala in the North Western Province of Sri Lanka. Ten households with husbands whose wives were abroad at the time and ten others whose wives had been abroad were selected for the study. Migration of a woman creates a functional vacuum in the household affecting its operations. The solution to this is often in the form of adjustment to the roles and status of the existing (functional) members of the household or through infusion of new members from the kinship network. When the husband takes the responsibilities of the wife it lowers the statusl social position of the husband in the eyes of the community because he is doing what is traditionally considered to be womens' work. The social position of the husband is particularly affected when he is substituting for his wife doing domestic chores and there is another person, proxy and female, managing the funds remitted by the wife. There are also some changes in the gender division of labour not only in "during migration household", but also in "post migration households". It was found that there was an increase in the number of husbands sharing work in the majority of households of returned migrants. The study showed that while the wife is abroad many husbands take up household activities traditionally performed by the wife. Although this happens out of necessity, the majority of husbands were found to be happy with this arrangement as they felt that they should contribute to running of the family as the wife is now the provider. Yet at times, they also felt that their changing gender roles negatively affected their social position (and male ego). However, household relationships led to conflicts when there was a proxy coming from outside, for example, a relative, managing the finances of the wife, as husbands do not feel comfortable with another person having control over the family budget. The social position of the husband also becomes a major issue when the proxy manager is a woman.
A preliminary study on bioactivities of Agave Vera - Cruz leaf extract
(University of Peradeniya, 2011-11-24) Karunaratne, K. U; Ranawana, K. B; Wickramasinghe, A
Agave vera-cruz is a perennial plant with large, spine-tipped leaves and short thick stems. It belongs to the family Agavaceae. It appears to be well established in Badulla, Nuwara Eliya and Kandy districts. Fibre obtained from this plant is used to make ropes, baskets and cloths. Freshly ground leaves of Agave vera-cruz are currently used as a piscicidal agent in fishing by remote farmers in the Knuckles region. The present study is an attempt to evaluate bioactive properties of Agave vera-cruz. Antioxidant, cytotoxic and phytotoxic properties were investigated. Plant materials were collected from Wattappola in Paranapattiya area. Freeze- dried plant materials were ground into a powder and extracted into methanol (MeOH). Concentrated crude extract was subjected to bioassay. Phytotoxic activity against Lactuca sativa, cytotoxic activity against Artemia salina and antioxidant activity were evaluated. Fractionation involved the use of VLC chromatography using Merck 9385 (40-63 Jim) silica gel, gravity column chromatography using 7734 Merck silica gel (63-200 ,urn) and analytical thin layer chromatography. LD50 value for cytotoxic bioassay was 675 ppm for the MeOH extract. IC50 value for the DPPH radical assay was 62.0 ppm. IC50 value for shoot inhibition was 1000 ppm and that for root inhibition was 1800 ppm. These results show that there are some allelopathic compounds present in Agave vera-cruz.
Demagnetization factor dependence of energy of Ultrathin Ferromagnetic films with four layers
(University of Peradeniya, 2012) Samarasekara, P.
The variation of energy with demagnetization factor will be investigated for sc(001) and bcc(001) ferromagnetic lattices with four layers using classical model of Heisenberg Hamiltonian. According to 3-D plots, the films with four layers can be easily oriented in certain directions under the influence of particular demagnetization factor and angles for both sc(001) and bcc(001) ferromagnetic lattice structures. A flat part can be seen in the middle of 3-D plots in addition to periodic variations. When the demagnetization factor is given by 0 dN = 6, sc(001) film with four layers can be easily oriented in 0.6 radians direction for the energy parameter values used in this simulation. Under the influence of demagnetization factor given by 0 dN = 5.2, thin film of bcc(001) lattice with four layers can be easily oriented along 0.63 radians direction.
Liquid Crystal Behavior of three Novel Glycosides
(2012) Abeyrathne, A. R. N. M.; Perera, A. D. L. Chandani; Karunaratne, D. N.
Novel glycosides synthesized by linking D-glucose to three different non-polar aglycones parts: cinnamyl alcohol, chloroxylenol and 3-pentadecylphenol show both thermotropic and lyotropic liquid crystal phases. The effect of inclusion of a rigid spacer in between hydrophilic and hydrophobic parts on the stability of liquid crystal phases is investigated. Both acetylated and deacetylated compounds exhibit thermotropic and lyotropic liquid crystal behaviour. The liquid crystal phases were confirmed as Smectic A, Smectic B and hexagonal columnar by X-ray studies
Evaluation of Ion Adsorption Capacities of Murunkan Clay and Coir as Cost Effective Materials for Desalination of Water
(University of Peradeniya, 2013) Dassanayake, Thiloka M.; Kottegoda, Nilwala; Perera, Chandani
The main objective of this study is to evaluate the suitability of Murunkan clay, a natural clay found in Murunkan, Mannar and coconut coir as low cost filter materials for desalination of water. Percentage removal of Na+ , K+ , Mg2+ and Ca2+ cations by these filter materials was studied. Water taken from Negombo lagoon was stirred in clay for 30 minutes followed by keeping in contact for different time periods of 0.5, 1, 2, 3, 4 and 24 hours using raw Murunkan clay. The same procedure was followed using acid treated clay up to 4 hours. To evaluate ion adsorption capacity of individual coconut coir types; red coir, pith-free coir and activated coir, lagoon water samples were passed through columns containing packed coir. Furthermore, the water samples were passed through a column combination of three types of coir after stirring in the clay for an optimum time period. The efficiency of raw Murunkan clay, acid treated Murunkan clay and three types of coir was evaluated for lagoon water containing Na+ , K+ , Mg2+ and Ca2+ 31,705, 639, 3,139 and 1,029 ppm respectively. The highest percentage removal of ions was observed when lagoon water treated with raw Murunkan clay was used in column combination with coir, leading to the percentage removal of 50%, 52%, 63% and 85% for Na+ , K+ , Mg2+ and Ca2+ respectively with a flow rate of 0.05 ml s -1 .

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