Science and Technology Degree Programme (SCT)

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Analysis of the Effect of Process Annealing for Deep Drawing Operation
(Uva Wellassa University of Sri Lanka, 2013) Niththiyananthan, Y.
The plastic forming process of sheet plate takes an important place in forming metals. The traditional techniques of tool design for sheet forming operations used in industry are experimental and expensive methods. Prediction of the forming results, determination of the punching force, blank holder forces and the thickness distribution of the sheet metal will decrease the production cost and time of the material to be formed. In this project, multi-stage deep drawing simulation of a cup has been presented with finite element method. The entire production steps with additional operations such as intermediate annealing and spring back has been simulated by DEFORM® software under axisymmetric conditions. The simulation results such as sheet thickness distribution, Punch force and residual stresses have been extracted in each stage and sheet thickness distribution was compared with experimental results. It was found through comparison of results, the FE model have proven to be in close agreement with those of experiment. Keywords: Finite Elements Analysis, Deep Drawing, Simulation
Antimicrobial Activities of Endophytic Fungi Isolated from Fimbristylis Miliacea
(Uva Wellassa University of Sri Lanka, 2017) Sivakumaran, A.
Endophytes are known to biosynthesis various bioactive secondary metabolites. Sri Lanka has a high rate of endophytic fungi of Cyparaceae Plant. Grasses and sedges are reported to harbour a lot of endophytic fungi & sedges are sparsely investigated for endophytic fungi and bioactive metabolites. Therefore the aim of this study is investigation of the antimicrobial activities of the endophytes of Fimbristylis miliacea, which may lead to the discovery of new drugs. Endophytic fungi were isolated from the surface sterilized roots and aerials parts of F.miliacea collected from Badulla & Mawanella and the antimicrobial activities were evaluated against S.aureus, P. aeruginosa, E.coli & B.cereus at 400 µg/disc concentration using agar disc diffusion method. The two most bioactive fungi were identified by morphological features and slide cultures. Ten & twenty morphologically distinct endophytic fungi were isolated from Badulla & Mawanella respectively. All the ten extracts from Badulla showed activity for at least one bacterium tested. Three extracts showed activity against all the four bacterial species while six extracts showed activity against three bacteria tested. Prominent activities (16 and 13 mm inhibition zones) were shown by the extracts FMR4 and FMR6 against B. cereus. The two most bioactive fungi FMR4 & FMR6 were tentatively identified as Fusarium sp. In conclusion, the data obtained from the current study revealed F. miliacea harbor endophytic fungi which produce secondary metabolites with antibacterial activities. Keywords: Endophytic fungi, Secondary metabolites, Fimbristylis miliacea, Antimicrobial, Fusarium sp.
Antimicrobial Activity of Ageratum Conyzoides Against Staphylococcus Aureus
(Uva Wellassa University of Sri Lanka, 2013) Dilrukshi, P.A.D.M.
Ageratum conyzoides is used in traditional medicine for the treatments of variety of alignment. The aim of this research was to formulate and evaluate the wound healing activity of methanolic extract of Ageratum conyzoides. Staphylococcus aureus is most common bacteria in wounds. The antibacterial activities of Ageratum conyzoides was investigated against Staphylococcus aureus, using the Well diffusion method. The solvent type extracts were obtained by soxhlet method with methanol. Solvent was removed by using rotary evaporator at 150rpm below 40°C and obtained semi solid slurry. Stock solutions were prepared by dissolving semi solid slurry with methanol. These were tested in varying concentration of 200mg/ml — 12.5mg/ml. The solvents were used as negative control. Solvents had no effect on the microorganisms. Each parts of Ageratum conyzoides such as leaves, flowers, roots and stems showed antimicrobial inhibitory activity at 200mg/ml. Highest inhibition zone was showed leaves of Ageratum conyzoides and inhibition zone was decrease when concentration decrease. MIC of the Ageratum conyzoides leaves extract is 12.5mg/mL determine through concentration series. This study suggests that the methanol extracts of Ageratum conyzoides, can be used as herbal medicines in the control of Staphylococcus aureus. Methanolic extract of Ageratum conyzoides leaves was used to formulate the herbal ointment. Formulations were then tested for its physicochemical properties. Further, herbal formulations were evaluated for its 'anti- bacterial activity against Staphylococcus aureus by agar well diffusion method using Betadine as the standard. The formulations showed predominant activity against selected species. This study showed that the leaf extracts of the Ageratum conyzoides plant, had good antibacterial activity against Staphylococcus ,aureus. Prepared herbal ointment also showed antibacterial activity against Staphylococcus aureus. That ointment had more than 50% consumer preference and didn't show any allergy reaction. Overall result of this study reveals that this is an effective herbal ointment. Key words: Ageratum conyzoides, Staphylococcus aureus, Well diffusion method, antibacterial activities.
Antimicrobial Activity of Piper Betelleaves, Momordica Charantia Seed & Centella Asiatica Root Extracts Against Microorganisms Associated with Fish Spoilage.
(Uva Wellassa University of Sri Lanka, 2013) Dissanayaka, G.A.A.P.
Spoilage of fresh and lightly preserved fish products is caused by mainly microbial action. So prevention of undesirable microbial actions in fish is important. For that we can use plant sources which are having antimicrobial activities. The objective of this study was to determine the antimicrobial activity of selected plant extracts against microorganisms associated with fish spoilage. Bacteria isolation was done from spoiled fish samples and it was carried out with serial dilution method, spread plate method & streak plate method. Finally 3 types of bacteria were isolated with different characteristics. Two of isolated bacteria & Staphylococcus aureus were subjected to the Screening of antimicrobial activity. For the extraction Piper betle leaves, Momordica charantia seeds and Centella asiatica roots were subjected. The extraction of this plant parts were carried out with soxhelet extraction method by using Methanol & Hexane solvents. Among them methanol extracts showed the highest crude for all plants. So methanol crude was chosen for the Screening of antimicrobial activity. Screening of antimicrobial activity was done by agar disc diffusion method. 5 concentration series were made for each plant extract for the disc diffusion method. (200mg/ml, 100mg/ml, 50mg/ml, 25mg/ml, 12.5mg/m1). Then disc diffusion was done for each selected bacteria with a positive control(methanol). Then inhibition zones for each bacteria & concentrations were obtained and minimum inhibitory concentrations were calculated. Finally statistical analysis was done to choose the best plant extracts for each bacteria strain. According to this study the methanol was the best solvent for extraction of selected plants(polar solvent). All selected plants have shown the antibacterial activities for selected bacteria. The highest effect was shown by Piper betel leaves and least effect was shown by Centella asiatica roots for all bacteria strains. The screening results of the study confirm the possible use of selected plants as a source of antimicrobial agent. Key words :- antimicrobial activity, spread plate method, streak plate method, disc diffusion method
Antioxidant Activity of Selected Red and White Rice (Oryza Sativa L.) Varieties of Sri Lanka
(Uva Wellassa University of Sri Lanka, 2014) Dodamgoda, G.H.D.I.U.
Rice (Oryza sativa L.) is the dietary staple in Sri Lanka. There are thousands of different Sri Lankan traditional rice varieties and nearly fifty improved rice varieties cultivated in different agrochemical regions in the country. Rice bran is one of the most abundant co-products produced in the rice milling industry and research conducted in last two decades has shown that it contains a unique complex of naturally occurring antioxidant compounds. However, Sri Lankan rice varieties have not gained significant attention on measuring these antioxidants. Therefore, this study was conducted to evaluate the antioxidant properties of some Sri Lankan rice varieties. Freeze-dried 70% ethanolic extracts of brans of five white and six red rice varieties were screened for antioxidant properties in this study. Antioxidant properties of rice bran extracts of selected rice varieties were evaluated by using total polyphenolic content (TPC) (n=3), ferric reducing antioxidant power (FRAP) (n=6), 1,1-dipheny1- 2-picryl-hydrazyl (DPPH) radical scavenging (n=3) and 2-azino-bis (3- ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging (n=6) in vitro antioxidant assays. Significant differences were observed among bran extracts of selected rice varieties for investigated antioxidant properties (P<0.05). Mean TPC, FRAP , DPPH and ABTS antioxidant properties were in the range of 9.33 — 212.33 mg gallic acid equivalents/g of extract, 1.13 — 18.89 mmol Trolox equivalents (TE)/100g of extract, 2.85-43.32 inhibition %, 23.93-98.34 inhibition % for 1 g rice bran respectively. Resulted mean values of the antioxidant activity of red rice varieties, for all four assays were significantly higher than that of white rice varieties. It is concluded that brans of Sri Lankan rice varieties, especially red rice varieties have higher antioxidant properties and could be use as potential sources for the prevention of chronic degenerative diseases in Sri Lanka. Key words: rice bran, antioxidant, in vitro, assay, chronic degenerative diseases
Antioxidative Properties and Lactobacillus Population in Traditional Sri Lankan Pickle During Fermentation
(Uva Wellassa University of Sri Lanka, 2014) Madusanki, K.S.
The aim of this study was to determine the functional properties of the traditional Sinhala pickle. The antioxidant activity, pH variation and Lactic Acid Bacteria (LAB) population in Sinhala pickle was evaluated using different analytical techniques: DPPH free radical scavenging assay was used to determine the antioxidant activity. The results showed that there was a significant changes (P<0.05) in antioxidant activity during fermentation. Total phenolic content (TPC) in pickle extracts initially increased from 11.7353± 0.16 mg/ml to 15.0893± 0.58 mg/ml and started to decline. Antioxidant activity in pickle reduced after 96 hours storage time compared to that in 0 hours. The results showed that, pH was almost same during the 10 days of storage, and it consisted within the optimal pH level for growth of the LAB. And results present that the bacteria population increased from an initial number of 8.0997± 0.56 Logi ocfu/g after 24 hours fermentation at 37 °C. The maximum bacteria growth was observed as 9.4248± 0.23 Logi ocfu/g after 48 hour's fermentation. After three days storage at 37°C, the bacteria population decreased but, no significant difference was observed with the storage time at 37°C. The present study demonstrated that after second and third day of preparation LAB, and total phenolic content reached to their optimum value and after that they started declining. pH value remained almost constant and fermentation retained 90-95% Antioxidant capacity during the 10 day of storage at 37°C. Second and third days after the preparation, can consider as the best consumption period of pickle to gain the additional health benefits beyond their basic nutritional value. Keywords: Antioxidant activity, Lactic Acid Bacteria, Total Phenolic content, DPPH assay
Automated Forklift Scheduling System
(Uva Wellassa University of Sri Lanka, 2017) Madushanka, K.R.
In the manufacturing organizations, forklifts can be seen and they are being used to carry various things that cannot be handled by humans. In Sri Lanka, most organizations don't follow any proper way to inform the forklift drivers about the jobs available. Forklift drivers has to be informed for the jobs manually. In this dissertation, a system to handle the forklifts more efficiently is described. This system can save time as well as can increase the productivity and it is cost effective. This research is mainly based on Arduino and GSM technology is used as well for the communication method. GSM technology is fast improving technology and it use for various projects in modern world. It is a good communication method than the other communication methods because the noises or the disturbances that can be occur during the communication is lower than the other types of communication methods. Arduino is used for all the processing parts and GSM module is used for the data transmission. There are two types of communication units were designed for the forklifts and the machines or the area of the work floor that produce the jobs for forklifts. When a product finished in the production machine it will automatically send a SMS or when a job is available in the working area, a laborer can send a SMS to all the units in forklifts and indicate about the job to the forklift drivers. Then they can either accept the job or they can reject the job. Multiple drivers can response to the job alert. The first person how respond to the job alert will receive the job and others will be informed about it. All the indications of the system are done using leds, to understand easily and make the attention of the forklift drivers.
Automated Lunch Packet System
(Uva Wellassa University of Sri Lanka, 2014) Lakmal, E.M.H.
In hotel industries they are suffering about their labor cost. This research shows simple solution for reduce lunch packet time and labor cost. Also help to carry consistency of a lunch packet rather than packing by manually. Using mechanical system which control by PLC found the solution machine. Rice and curries are pre loaded in to the buckets in the machine. First stage of this machine can make approximately fifty lunch packets. Operator can select the type of lunch packet using control switch in machine. So using this machine reliable to the shop owner to count the number of lunch packets sold, no need to pay for a labor, and the efficiency will be increase.
Automated Plates Washer
(Uva Wellassa University of Sri Lanka, 2017) Herath, H.M.A.D.K.
Washing plates normally done by hand and it uses water, energy, chemicals as well as need to spend valuable time. So an efficient approach can save a lot of each. Though the dish washing machine gives some relief for that, the existing dishwashing machines in the world market consist many defects in the system such as wastage of water, requirement of man power, high installation cost, poor quality of cleaning etc. Specially, there is no proper turning off system when the washing is complete, and because of that it waste large amount of water. This project is about inventing an Automated plates washer which can be overcome the problems in existing machines. It includes automatically turning off system after the plates are cleaned. The system is controlled by arduino and has to supply high pressure water to the machine to start the washing process. Then the sensor will give the signal to turn off the machine when the process is complete. This system can be used in large scale kitchens such as in marriage ceremonies, receptions, business parties, etc. where there is requirement of more number of plates. Not only that this plate washer is useful for household use as same as the washing machine, which can save time and cost rather than spending in washing plates by hand and wasting large amount of energy.
Characterization of Iron Particles for Nitrate Reduction
(Uva Wellassa University of Sri Lanka, 2013) Ratnasekara, S.K.S.S.
Chemical reduction of nitrate by metallic iron (Fe°) was studied as a potential technology to remove nitrate from water. So it's very important for studying about characterization parameters of iron particles relevant to nitrate reduction. Recent studies have demonstrated the efficacy of zero-valent iron nanoparticles for the transformation of halogenated organic contaminants and heavy metals. X-ray diffraction (XRD) method was used to characterize the identification of the iron particles. To measure the particle size sieve analyzing technique was used. In nitrate reduction process by using iron particles ammonia was the end product of nitrate reduction and accounted for all nitrate transformed under our experimental conditions. Nitrate reduction efficiency mainly affected by the particle size, pH of the solution. Metallic iron particles act as catalysts in the nitrate reduction process.
Comparative Pharmacognostic Aspects of Rauvolfia Serpentina (L.) Benth. Ex Kurz and it's Substitute Rauvolfia Canescens L. (Apocynaceae)
(Uva Wellassa University of Sri Lanka, 2014) Savithri, W.A.K.
Rauvolfia serpentina (L.) Benth. ex Kurz (Apocynaceae), a rare, therapeutically important medicinal plant, is often adulterated by materials of Rauvolfia canescens L. (Apocynaceae). However, adulteration of R. serpentina with R. canescens without scientifically proven data on important quality standards might adversely affect the therapeutic properties of the herbal drugs. Therefore, the present study was undertaken to establish a comparative quality standards on morphological, anatomical, phytochemical, physicochemical and cytotoxicity activity of R. serpentina and R. canescens by using established protocols. Results demonstrated that R. serpentina could be distinguished from R. canescens by comparing polymorphological characters and anatomical characters. Major phytochemical groups were present in leaves, stems and roots of both plants. Results of Thin Layer Chromatogram (TLC) exhibited the highest number of common spots in leaf extracts followed by stem and root extracts of both R. serpentina and R. canescens. The presences of higher brine shrimp toxicity in root extracts of both plant species scientifically validate the use of root in medicinal purposes in Ayurveda and traditional systems of medicine in Sri Lanka. Information generated through the present study could be effectively used for the quality control and standardization process of different parts of Rauvolfia serpentina and Rauvolfia canescens in order to upgrade the Sri Lankan pharmacopeia. The presence of certain similarities in major phytochemical groups of R. serpentina and R. canescens justifies the use of R. canescens as a substitute for R. serpentina in traditional systems of medicine in Sri Lanka, which needs to be confirmed after further clinical trials. Keywords: Apocynaceae, Rauvolfia serpentina, Rauvolfia canescens, Polymorphological Characters, Phytochemical, Physicochemical
Convert 2d Images to 3d Image
(Uva Wellassa University of Sri Lanka, 2013) Gaspe, G.M.S.M.
Image processing plays a major role in modem technology. Implementations of this field are varying from simple applications like documentation to complex applications like space context. Before use in the above applications images should be processed using relevant techniques. There is lots of software that can process the images and get the outputs to be use in the above mentioned applications. To be use in applications like automatic navigation of robots and vehicles, satellite identification and fault diagnosis, medical reasoning and remote surgery, conversion of 2D images to 3D images is important. There are many algorithms which have been developed in order to obtain 3D images using 2D images. Matlab software includes many functions, data types and devices which supports to developing new algorithms. This algorithm uses stereo images, red, cyan composite images, basic block matching, depth mapping and noise filtering. The final outcome of above steps is a 3D image with fewer errors and less time consuming.
Designing and Development of A Fully Automated Solar-Powered Lawn Mower
(Uva Wellassa University of Sri Lanka, 2017) Pakirathan, R.
This Project aimed to design a fully automated solar-powered lawn mower (FASPLM) of electrical source to reduce the environmental pollution and use the natural resources in effective way. This device consisted of a square cross sectional cutting thread which is operated by the efficient powered motor and the power supply for the motor is given by a rechargeable battery. The battery can be charged by using a solar panel. The obstacles in the moving path of the mower can be sensed by an ultra-sonic distance sensor to avoid the obstacles in the track. Moreover, it has PIR sensors for detecting the human motion near the lawn mower. This design requires no perimeter wires to maintain the mower within the lawn and it will avoid and detect objects and human motion as it uses a self-localization platform with a global positioning system (GPS) module to travel and uses efficient cutting algorithms. Initially, the market survey and literature survey were carried out to study the advantages and disadvantages of the existing devices. Then according to the survey results, a suitable platform for the lawn mower was designed. Thereafter, a detailed mechanical design and the mechanical structure were developed. Then the mechanical structure was fabricated, following that mechanical parts and the electronic wiring were assembled. The control algorithms and coding were written appropriately. Finally, manufactured equipment was tested in the field. The major drawbacks of this device are with navigation control and duration of battery life. This lawn mower used GPS for localization and track following, coding and mechanical construction of GPS module is little difficult. Furthermore, during the long time of operation the battery discharging rate may be greater than the charging rate, therefore it is expected to use efficient motors, and efficient solar panels to keep the battery for long time operation.
Determination of Bacteriostatic Activity of Ethanol Extracts from Pleurotus Pulmonarius and Polyporus Arcularius Against Selected Antibiotic Resistant Bacteria
(Uva Wellassa University of Sri Lanka, 2013) PERERA, A.A.S.D.
This research study was undertaken to determine the Bacteriostatic activity of ethanol extracts from Pleurotus pulmonarius and Polyporus arcularius against antibiotic resistant bacteria species, Staphylococcus aureus (gram +ve), Enterococcus faecals (gram —ve) and Salmonella typhi (gram —ve). Bacteriostatic activity was tested by using the disc diffusion method. Preliminary test was done with 100 mg/ml concentration, where 100 mg of the extract was dissolved in lml of acetone. This was done to three different bacteria separately. Concentration series were made and the minimum inhibitory concentrations were found for three different bacteria. It was found; with the decreasing of concentrations MIC was decreased. MIC for ethanol extracts of both fungi species was found to be 12.5mg/ml. P. pulmonarius and P. arcularius can be successfully used to inhibit the three selected antibiotic resistant bacteria. P. pulmonarius was found to be more effective than P. arcularius against all three antibiotic resistant bacteria tested. It was showed that, with the increasing of incubation period (more than 72 hours) inhibition zone diameters were getting decreased. According to that Effect of ethanol extracts of Pleurotus pulmonarius and Polyporus arcularius seems to be Bacteriostatic rather than bactericidal. Key Words: Bacteriostatic activity, Pleurotus pulmonarius, Polyporus arcularius, Salmonella typhi, Staphylococcus aureus, Enterococcus faecals, Disc diffusion method.
Determination of the Insect Repellent Activity of Herbs on Sitophillus Oryzae
(Uva Wellassa University of Sri Lanka, 2017) SAJITHTHA, B.
Natural products from plants are known as secondary metabolites. These compounds show several biological properties including insecticides activity. Storage losses in paddy alone have been estimated to be 4-6% and it had been estimated that 80% of this loss is due to insect attack. Based on, this research mainly focused on to protect the rice from Sitophilus oryzae by using herbal plant extraction. In Sri Lanka, only a limited number of studies have assessed the insecticides properties of herbs. Therefore, in this study, insecticides activities of selected three herbs species and their cytotoxicity were tested. Samples were collected from near to university premises. Using methanol extraction, herbs was extracted from three species,Cinnamomum cassia, Plectralthus amboinicus, and Aglaia roxburghiana . plant extract were tested for their insecticidal activities against adults of Sitophilus oryzae, using direct contact application. Responses varied with plant material, insect species, and exposure time. Testing was carried out for different concentrations of extracts (153.06 fig/cm2, 458.18 tg/cm2 and765.30). Insecticidal activity and best plant were discovered for Sitophilus oryzae . Methanol extracts of all plans showed insecticidal activity against tested insects. Best plant/s and part/s is leaf of Cinnamomum cassia, and least insecticidal activity shows Plectralthus amboinicus leaf. Toxicity assay was done to test the toxicity of plants. Artemia salina was used for toxicity assay. The results from toxicity assay, a leaf of Aglaia roxburghiana is having the high toxic and leaf of Plectralthus amboinicus is having the lest toxic. The results from this study confirm insecticidal activity in Aglaia roxburghiana, Plectralthus amboinicus and Cinnamomwn cassia. Further research is needed to identify the individual compounds responsible for insecticidal activity, which may in turn lead to developing natural insecticides from locally available herbs. Key words: Insecticidal activity, cytotoxicity and secondary metabolites.
Development of A Classification Scale and A Model for Fiber Saturation Point Andshrinkage of Sri Lankan Timber Species
(Uva Wellassa University of Sri Lanka, 2013) KUMARI, H.M.A.S.
Sri Lanka produces valuable and exquisite timber species and those are extensively used for many purposes. For efficient use of the timber understanding of physical property of them is a must. Research was done on physical property of wood specially, timber density and volumetric shrinkage is very few and far better. Timber seasoning without considering its shrinkage properties increases the cost of seasoning and wastage the timber. Timber density calculated by Archimedes theorem. To find out the shrinkage values, the dimensions of the timber samples were measured in green to oven dry and the percentage of shrinkagewas calculated. Also, there is a strong correlation (P value<0.05) between moisture content at fiber saturation point and density and volumetric shrinkage and density. As the final conclusion,The Radial Shrinkage for most of the timber species tested varied between 4.6- 5.5. % and The Tangential Shrinkage for most of the timber species tested varied between 8.5-9.5%. The density value varies within (650-750kg/m3)range for most of the local timber species.The moisture content at Fiber Saturation point varies between 30-35 % for most of the timber species in Sri Lanka. The model has been developed to explain the Moisture content at FSP asY (MC (% at FSP) = 93.23-0.08219 Density (P value<0.05;R-sq= 88.1%, R-sq (adj) = 88.0%, DW= 0.69081 ) and volumetric shrinkageas Y (Volumetric Shrinkage (%) = -2.943 + 0.02112 Density (P value<0.05;R-sq= 88.5%,R-sq (adj) = 88.3%,DW= 0.834763). Key words:Fiber Saturation point, Volumetric Shrinkage, Radial Shrinkage, Tangential Shrinkage, Longitudinal Shrinkage, Density, Specific Gravity, Oven dry method, moisture content, Hardwood, Softwood, Heart wood, Sapwood ,Green Wood.
Development of A Colorimeter for the Field Estimation of Fluoride in Drinking Water
(Uva Wellassa University of Sri Lanka, 2012) KUMARI, W.G.N.D.
The name "colorimeter" is given to any instrument used for the determination or specification of colors. One type of colorimeter is an instrument used to find the concentration of a substance in solution, based on the intensity of color of the solution. If the solution to be tested is colorless, a reagent is added that reacts with the substance, producing a color. This type of colorimeter has a wide range of applications, including laboratory research, environmental analysis of water quality, analysis of soil components, monitoring of hemoglobin content in the blood and analysis of chemicals used in various industrial settings. Presence of excess fluoride in drinking water causes various diseases that are collectively referred to as fluorosis. Fluorosis is endemic at least in 25 countries. The total number of people affected due to fluoride estimated is tens of millions. The major source of fluoride is lithogenic. Fluoride enters to the human body mainly through water. A minimum amount of fluoride is required in drinking water to prevent tooth decay. According to the WHO guidelines, the permissible limit of fluoride in drinking water is 1.5 mg/L. However, a regular in take of water containing excess F— causes many chronic diseases. In this project a novel colorimeter is designed to determine fluoride concentration in water. The unit has alarming signals to alert people when the levels far exceed WHO recommendations. The colorimeter works according to Beer-Lambert Law of absorption. . It is used in conjunction with the SPADNS method, which shows a color change in the visible region on addition of water containing fluoride lo a reagent solution. That color region was identified by web cam and read the color intensity.
Development of A Mosquto Repellent Bodylotion from Essential Oil of Eucaliptus Grandis Leaves
(Uva Wellassa University of Sri Lanka, 2013) WIJERATHNA, W.M.K.G.
Eucalyptus grandis is an introduced timber crop which grows well in up country of Sri Lanka. Main objective of E. grandis cultivation is to obtain the timber. But it has a pharmacological importance due to the natural compounds produced as secondary metabolites. Repellency of essential oils of E. grandis against mosquitoes has not been studied. This study was conducted to find out the mosquito repellent activity of E. grandis species. Essential oil of E. grandis is extracted by hydro-distillation of matured leaves. This method was selected by referring previous studies done to extract essential oil from Eucalyptus species. Repellency of the essential oil was tested against mosquito species isolated from environment using five different concentrations of oil as 50 100 gl, 150 200 pi and 250 O. Mosquitoes at same age were isolated from monitoring controlled conditions at clean water bath and mosquito identification was done by morphological characteristics and life cycle study. Mosquito species isolated was Aedes vexans. 200 ul was the most effective concentration of mosquito repellency. Repellency of oil increased with the time. Mosquito repellent lotion was prepared adding 1 ml of essential oil in to 10 g of base cream. Sensory analysis was conducted to determine the acceptability of the product and results implied that the lotion is acceptable. Repellency time was determined by human trial after testing for allergic reactions where it displayed no allergies. Lotion was applied to a 16cm2 area of skin and expose to mosquitoes for five minutes at thirty minute time intervals. Repellency of the lotion was compared against commercial mosquito repellent and results shows that it has different repellency to the commercial repellent But it had maximum repellency over two hours. Key words: Eucalyptus grandis, essential oil, repellency, body lotion, mosquitoes
Development of a pH Responsive Ceramic Material
(Uva Wellassa University of Sri Lanka, 2017) Mahanama, M.G.C.
Not only human been as well as all the animals consume food items daily. They cannot continue their lives without food items. Food spoilage is a big problem to the food industry. Because of the bacteria and other microorganisms acted in food items. This cannot be overcome but able to be controlled. In food industry the most difficult thing is to identify the food whether it is spoiled or not. From this research that blank will be fulfilled. Because this research introduces a pH sensitive smart bottle cap. When the pH is going to change this pellet will be easily identified by giving a color change. When some food item is being spoiling, there will be produced lactic acid. Because of acidic condition pH will be reduced. That pH variation can be identified by pellet. Kaolin is the ceramic material which is used in this research. Here it used kaolin because of non-toxicity & chemical inertness. Then kaolin material prepare for the condition which can absorb dye material as well as to obtain clear view of color change. This research used four types of dye materials. Two of them are consisted with anthocyanin and other two are commercial dyes. Anthocyanin can undergo molecular rearrangement due to polyphenolic group and extended conjugation of double bond depending of pH of medium. Also in methyl orange and methyl red, they show different colors in acidic and basic conditions. Other important thing is those dyes are low toxicity and may not be able to effect to the food item. The main objectives of this research are checking the air stability of these dye, prepare the pH series of dyes and check whether how they react with the dyes, check whether the dye absorbed pellets are reacted with the acidic, basic conditions as well as spoiled and non spoiled milk and finally develop the bottle cap. The air stability of those four dye materials have been checked by the UV visible spectrometer. For the red cabbage, there were increased of absorbance gained after 72hours. The pH reduction average is 34.04% after72 hours. Same as the Hibiscus dye also shown, a increase of absorption and reduction average of pH 25.35% after one day. Same as methyl red dye, it shows 11.7% increase of absorption after one day. Also it shows 20.045% of pH reduction after one day. In methyl orange, it shows 67.67% of absorbance increase and 19.3% of pH reduction. ii Red cabbage absorbed pellets show yellow color for the 1M sodium hydroxide and pink color for the 1M sulfuric acid. For the spoiled milk blue color pellet shifted to the purple as well. Same results were obtained for the Hibiscus dye. Methyl red shows yellow color for 1M NaOH & red color for 1M sulfuric acid. Also it shows brownish color for the spoiled milk as well. Methyl orange dye shows yellow color for the 1M NaOH and no color change obtained for the 1M sulfuric acid. Then it shows brown color with the spoiled milk as well.
Development of Ag20/Zno Composite Photocatalyst for Methyl Orange Degradation
(Uva Wellassa University of Sri Lanka, 2015) Gunarathna, T.M.S.
Environmental pollution is contamination of the Biological, Physical and the Chemical components of the Land, Water and Air. It can cause harm or discomfort to the humans or other living organisms in the environment. Dyes may adversely affect the aquatic life because of the presence of aromatic materials, metals and chlorides. Therefore, for water treatment processes, dye removal is important. This study is focused on development of a composite material to remove organic pollutants in waste water. Model pollutant used in this study is Methyl Orange (MO) and composite is Ag20/ZnO. Then the capacity of Ag2O/ZnO to act as a photocatalyst to degraded organic dyes was evaluated and find optimum conditions/ composition of the composite. Results indicate the composite material can successfully degrade MO under visible light. The highest degradation rate which 74% was observed for the optimum composition of Ag2O: ZnO ratio 3:5. To find the concentration of the unknown solution used an equation known Beer's law, A = s 1 c, Where A is absorbance, c is the molar absorptivity, 1 is the path length and c is concentration of the solution. The degradation efficiency is calculated by Degaradation%= (A-Ao) / Ao * 100 Where Ao represents the initial absorbance, A represents the reaction absorbance of the MO at the characteristic absorption wavelength of 465 nm. Freundlich adsorption isotherm is used, x/m = kpl/n or log x/m = log k + 1/n log P Where x is the mass of the gas adsorbed on mass m of the adsorbent at pressure p and k, n are constants whose values depend upon adsorbent and gas at particular temperature.

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