PURSE 2001

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A New Treatment Schedule For Canine Filariasis
(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Wijayawardhane, K. A. N.; Dangolla, A.; Silva, I. D.
This paper reports a new treatment schedule for canine filariasis and describes the clinical signs and the blood picture of three out of fifteen filaraemic dogs. The dogs described were between 2 and 9 years of age , and were either Mongrel, German Shephered or Golden Retrievers. The complaints made by the owners were anorexia, skin rashes and periodic blindness. Clinical manifestations of the dogs varied from mild to critical anaemia, ascites, oedema of the dependent parts and fever. Examination of microfilaria in a drop of blood and using the Knott's technique revealed the presence of microfilaria ranging from 300 to 20,000/ml of blood. The dogs were treated with Levamisole 10-11 mg/kg body weight, orally, once daily for six consecutive days. An antihistamine was given to counteract the allergic reactions due to dying filarial worms. Six days after Levamisole treatment, the microfilarial count had dropped to zero except in one dog which had a count of 36/ ml of blood. Subsequently, the microfilaricidal therapy with ivermectin was administered. During and after treatment, the kidney functions were also assessed by urine analysis and was found to be normal. Conventional microfilaricidal treatments are diethyl carbamazine citrate (DEC) and ivermectin, These drugs may show various side effects. DEC needs to be used for a longer period and may cause anaphylactic reactions and is also not recommended to be used in microfilaraemic dogs. The dramatic decline in microfilarial counts, which usually occur with in the first several hours after administration of ivermectin, may account for some acute adverse effects such as shock, renal impairment and diarrhoea.
A practical guide on phytohormones for G. C. E. Advanced Level biology students
(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Wijeyaratne, W. M. P. K. M. C.; Karunaratne, A. M.
This study was carried out with the aim of developing a practical guide for the G.C.E. Advanced Level Biology students, on phytohormones, as there are no laboratory exercises recommended in the present Advanced Level guide under this section. As the commercially available purified plant hormones are very expensive, natural sources and commercially available artificial sources of hormones were tested. Rooting powder is composed of auxins such as mA (Indole Butyric Acid) and NAA (Naphthalene Acetic Acid). In Sri Lanka rooting powder is available by the trade names "Hormone rooting powder", "Secto" and "Rooton". These can be used as a source of auxin in some experiments. Ethylene was obtained from natural sources such as ripe bananas and ripe passion fruits and from the chemical preparation of Ethrel (a commercial spray for initiation of flowering in pineapples) with sodium hydroxide. Phototropism shown by plants due to action of auxins was demonstrated using mung seedlings. Apical dominance of balsam (Impatience sp.), root initiation of African violet (Saintpaulia sp.) leaves and the influence of hormone concentration in rooting of onions and garlic using rooting powder as source of auxin were studied. Particular emphasis was paid to recording observations-in these experiments. The effect of ethylene on fruit ripening was studied using ripe 'Embul' bananas as the source of ethylene and the same experiment was repeated using passion fruit as the natural ethylene source. Passion fruits were found to be more effective in these experiments. Using passion fruit as the source of ethylene, leaf senescence of 'Kankun' (Ipomoea aquatica) and flower senescence of temple flower (Plumaria acuminata and Plumeria rubra.) were studied. The ethylene generated by the reaction of Ethrel with sodium hydroxide could be used to ripen 'Embul' banana in the laboratory. Other plant hormones tested out were cytokinins and abscisic acid. Coconut water was not effective as a natural source of cytokinins as it tends to ferment. Crude extracts from the dormant buds of potato were not a good substitute for abscisic acid, as typical symptoms of abscisic acid such as leaf senescence or chlorophyll breakdown were not observed when applied on Geranium (Pelargonium sp.) leaves. A practical guide on phytohormones was prepared, which included nine laboratory exercises to demonstrate the action of auxin and ethylene using natural and artificial sources.
A preliminary investigation on seed dormancy in Coscinium Fenestratum (Colbr.) (Menispermaceae)
(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Ariyarathna, H. A. C. K.; Tennakoon, K. U.; Gunatileke, I. U. A. N.; Gunatileke, C. V. S.
Coscinium fenestratun (Weniwel, Calumba wood) is naturally found mainly in the forest fringes and disturbed forests in the lowland wet zone of the island. This species has a well-established local market and a potential foreign market for its medicinal properties. As a result of illegal exploitation, destructive collection and the relatively slow growth rate natural populations are disappearing at an alarming rate. The meager supply of propagation material is one of the primary impediments to its mass-cultivation. Seeds of Coscinium. fenestrartum have a relatively long period of dormancy (40-364 days) and germination under natural conditions is less than 20%. This study examined the possible causes of seed dormancy and attempted to develop techniques to overcome it. Fruits were bagged and collected from the peripheral areas of Sinharaja MAB Reserve, and used for the experiments after four months of storage. Fruits were depulped, surface sterilized with I % Sodium hypochloride before storage at 25° C and 70 % humidity. The average seed weight was 1.76 g and the average seed length and width were 1.72 cm and 1.45 em respectively. According to seed anatomical studies, the average seed coat thickness was 1.62 mm. The embryo was located deeply within the invaginations of the endospermic tissues. The thick, stony seed coat (integument) and the dry and hard endospermic tissues act as mechanical barriers to the developing embryo. The seed coat consisted of a compactly arranged lignified strongly water repellent macrosclereid layer that impedes the imbibition process. Bioassays were conducted using Brassica junceae L. to examine the presence of germination inhibitory substances in the seeds C. fenestratum. Water extracts from the seed coat (A) and the endosperm and embryo tissue (B) were prepared at 2 % and 5 % concentrations. For the controls 2% and 5% sucrose solutions were used. Brassica junceae seeds germinated on filter paper soaked in the control solutions gave 100 % germination. Seeds placed on 2% concentrations of extracts of A and B, also gave relatively high germination (80 - 99 %). In contrast, that using the 5 % concentrations of A and B gave very low germination (2 - 5 %), suggesting the presence of inhibitors even after 4 months storage. Results of chromatographic and spectroscopic investigations of the seed resources of Cfenestratum showed that the endosperm contained comparatively high percentage of carbohydrate (67.33%) and lipids (3.12%) suggesting that the seed could remain dormant for a long period. However, the protein (5.03%) content was comparatively low. The amino acid profile was nutritionally balanced and rich with the essential amino acids (His, Gly, Ala, Glu, Pro, Val, Phe, Lue). Experiments on C. fenestratum carried out to study the effect of the external application of 5% gibberrilic acid, and the red/far red ratio did not enhance germination.
A preliminary study on the gut parasites of Ramanella Obscura (anura: Microhylidae)
(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Lokuhewage, S.; Amerasinghe, P. H.
Ramanella obscura (Gunther, 1864) is an endemic species of frog in Sri Lanka. Although some aspects of its biology are known, studies on endoparasites of this frog are lacking. Present study investigates the gut parasites of Ramanella obscura. A total of 155 tadpoles and 2 adults collected from two man-made ponds (A and B) at Sarasavigama (Kandy District) were examined for gut parasites. Tadpoles (n = 5) were dissected at weekly intervals for parasite counts and species identification. Light microscope measurements of parasites (n = 30-50 parasites/observation) were made after staining with Delafield's Haematoxylin and alcoholic Eosin. Morphological features and light microscope measurements were used for species identification. The two frogspawns examined contained 327 and 220 eggs respectively. Embryonic development from fertilization to hatching took 48-72 hours. Emergence of adults from the two ponds observed was observed at 80 and 101 days respectively. Protozoan parasites belonging to three genera (Opalina, Protoopalina, and Nycototherus), their juvenile and sexual forms were observed in the guts of tadpoles. The species identification of juveniles was not possible, as all morphological features were not developed. Only Opalina and one nematode parasite species (unidentified) was observed in the limit number of adults examined. In general, prevalence of infection in tadpoles, for all protozoan species ranged from 20-80%. The parasite abundance in tadpoles from both spawns ranged from, Opalina 5-1902, Protoopalina 6-816 and Nyctoterus 1-28. Mean length (Jim) and width (11m) of parasites collected at weekly intervals, from tadpoles and adults of ponds A and B ranged from, Opalina, 70.06±28.06 - 106.12±15.28 and 23.78±7.69 - 79.04±19.40; 43.89±4.95 - 153.54±49.53 and 16.23±2.50 - 41.17±11.03; Protoopalina, 97.79±8.50 - 113.22± 2.67 and 19.9±1.70 - 31.30±3.19; 75.58±19.81 - 116.23±22.17 and 13.83±6.89 - 20.24±4.74; Nyctotherus, 19.54 - 155.50 ± 59.22 and 10.66- 114.65±51.69; 60.38 - 154.88± 76.26 and 37.29 - 108.97±73.68 respectively. At both ponds, infections with Opalina, occurred first (42 and 27 days respectively), followed by the other two protozoan infections (50 and 34 days respectively). For all parasite species, the highest number of parasites was collected from tadpoles in Pond B. Only a limited number of adults were available for observation. Tadpoles of Ramanella obscura become infected with protozoan parasites (Opalina, Protoopalina, Nyctotherus) during early development. Infections occur through the ingestion of cysts of the parasite, which are usually discharged into water by the adult frogs during the breeding season. The abundance and sizes of protozoan parasites varied, probably due to the available nutrients, overall density of the parasites per host and also environmental conditions. The absence of Protoopalina and Nyctotherus, in the frogs cannot be explained due to the small sample size examined during this study. Nematode infections occur only after tadpoles reach adult stage. To the best of our knowledge, this is the first record of the parasite fauna of Ramonaella obscura. Further studies need to be done for the identification of the parasite species. Studies such as these contribute to the knowledge and understanding of co-evolution of hosts and their parasites.
A preliminary study to detect antibiotic residues in fresh milk
(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Hathurusinghe, M. H.; Piyankarage, R. H.; Abeynayake, P.; Jayaweera, W.
Due to the wide usage of antibiotics in the treatment and prevention of diseases in dairy cows, there is a likelihood of antibiotic residues occurring in milk. Such residues can cause several adverse effects in humans including hypersensitivity reactions. These residues may also interfere with bacterial starter cultures used for preparing of curd, yoghurt and cheese. This study was designed to screen milk for the presence of antibiotic residues. The study was carried out in 74 dairy cows reared in certain selected areas of the Kandy district. After taking the history of each cow, milk samples from each animal were obtained into sterile bottles at the time of milking. Before performing the screening test, the samples were heated at 100°C for 5 minutes to destroy natural inhibitory substances in raw milk. For negative control, 2 ml of 10 % skimmed milk heated at 110°C for 10 minutes was used. The positive control was a 2 ml milk sample containing 0.006 ug/ml of benzathene benzyl penicillin. A prepared test culture of 0.2 ml of Streptococcus thermophilus strain T.J. containing yeast-extract and bromocresol purple (as pH indicator), were added to each 2 ml of milk sample and placed in a water bath at 45°C ± 0.5 for 2.5 hours. Bromocresol purple is purple at the beginning and turns yellow due to acidification during the growth of the bacteria. Retention of the original purple colour indicates that the bacterial growth has been inhibited and such samples were considered as positive. The samples that gave a yellow colour were considered as negative. Out of the 74 samples tested, 7 samples (9.5 %) were found to be positive and 63 samples (85.1 % ) were negative for chemical inhibitory substance. Four samples (5.4%) gave intermediate colours indicating doubtful results. The positive results could be due to the presence of antibiotic residues or other inhibitory chemicals in raw milk. Serial dilutions of antibiotics prepared in skimmed milk were used to detect the level of sensitivity of the test. Penicillin and oxytetracycline gave the colour change at >0.005 ug/ml. Cloxacillin gave the colour change at 0.5 ug/ml where as gentamycin changed the colour at 0.5j.tg/ml concentrations. Chloramphenicol gave the colour change at 100 ug/ml. Therefore the test was found to be highly sensitive to penicillin and oxytetracycline antibiotics, whereas Chloramphenicol was found to be the least sensitive antibiotic for this test. The results revealed that the fresh milk is not totally devoid of inhibitory substances and further studies are necessary to specify the chemical and to quantitatively determine its concentration.
A study of abnormal teeth "Concrescence" and " Fusion"
(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Mohamed, Y. S.; Arambawatta, A. K. S.; Priyadharshani, A.; Nanayakkara, C. D.
Gemination, Fusion and Cocrescence are developmental variations of deciduous and permanent teeth. Gemination is an anomaly that arises when a tooth attempts to divide itself, or partially twin itself, by splitting its tooth germ. It therefore a developmental anomaly. Gemination could occur if a tooth completely divides into two separate entities. In most cases, however, geminated teeth are only partially split. Usually the geminated teeth have a single root and a common pulp canal. Fusion occurs when two adjacent tooth germs unite. The two teeth may be united along a part or the entire length. They may be joined by the crown dentine or the root dentine. If the teeth are only connected by the cementum, then it is referred to as concrescence. If fusion occurs, two teeth are joined and therefore, there is one missing tooth in the dentition. Concrescence is a type of fusion that occurs after the roots have formed. It is thought to occur sometimes as a result of trauma. It occurs when two approximating roots contact and fuse by the deposition of cementum following hypercementosis associated with chronic inflammation. It can occur before or after eruption. If one of the teeth involved require an extraction, surgical sectioning will be needed to save the other. Extracted teeth have been collected for teaching purposes in the Division of Dental Anatomy during the past two years. Among this collection, there were two fused teeth and in order to find out whether these teeth were geminated; fused or showed concrescence, stained ground sections of these teeth were prepared. The fused teeth included a maxillary permanent left second and third molars belonging to a 35 year old female and mandibular permanent right and left central incisors belonging to a 28 years old male. The aim of this poster is to show the macroscopical and radiological appearances and photomicrographs of ground sections prepared using the above teeth.
A Study of electrical conductivity of Peo-X solid polymer electrolytes with X= LiCf3 So3 ZnC7 H5 O3 and PbI 2
(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Bandara, L. R. A. K.; Abeykoon, A. M. S. B.; Bokalawela, R. S. P.; Dissanayake, M. A. A. K.
Solid polymer electrolytes occupy a unique posrtion in the development of a new generation of power source applications ranging from small portable electronic equipment to larger electric vehicles. These polymers, in thin film form, display many advantages over liquid electrolytes such as leakage proof and gassing. further, they show dual action both as ionic conductors and mechanical separators, which make them the most attractive solid polymer electrolyte in conducting polymer-based batteries. A wide range of salts can be dissolved in poly(ethylene oxide) (PEO) to form solid polymer electrolytes whose transport ions may be cations or anions. In this work, PEO based electrolyte films with three types of salts, namely lithium triflorosulfonate (LiCF3S03), zinc salizelate (ZnC7Hs03) and lead iodide (Pbh) were used and their electrical conductivity measurements were carried out. Samples have been prepared by the solvent casting technique. The complex impedance measurements were performed over the frequency range of 5 Hz to 13 MHz, using a computer controlled HP4192A impedance analyzer with an applied signal of 0.1 V. The impedance data were collected in the temperature range of 25°C to 85 "C. DC polarization test was carried out on all the samples, using both the blocking and non blocking electrodes, to estimate the tranfrerency numbers of the polymer electrolytes. Compared to the other two systems, PEO-LiCF3S03 system shows higher ionic conductivities. With both ZnC7Hs03 and Pbl- salts, PEO based solid polymer electrolytes show almost the same conductivity values within the studied temperature range. In all three systems, the ionic conductivity increases linearly with increasing temperature. The knee observed in these conductivity curves are assumed to be due to the melting of the crystalline phase of pure PEO. It was observed that the ionic conductivity is high in the amorphous phase above 55°C, in the presence of a flexible polymer chain. Results of the dc polarization test showed that all the studied samples had low electronic conductivities. According to the above results, PEO- LiCF3S03 and PEO-ZnC7Hs03 systems can be mainly considered as cationic conductors while the PEO-PbI2 system acts as anionic conductors.
A study of electrical properties of zircon ceramics doped with different dopants
(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Dahanayake, U.; Karunaratne, B. S. B.
Zircon (ZrSi04) is tetragonal: 141/ amd, Z=4 and the ideal structure consists of chains of alternating, edge-sharing Si04 tetrahedra and ZrOs triangular dodecahedra extending parallel to crystallographic axis c. Zircon is an abundant and inexpensive natural mineral and is mined in very large quantities throughout the world. This material is recognized as a potential ceramic material for the applications at high temperature due to its good combination of many attractive properties such as low thermal expansion, low heat conductivity, good chemical stability, excellent thermal shock resistance and good high temperature properties. Although, many studies on structural properties of zircon ceramics have been reported in literature, electrical properties of zircon has received less attention. It was one of the two reasons why this material was selected for this investigation and the other was the superfluity of zircon in the coastal areas of Sri Lanka. This paper presents the results of a preliminary study on electrical properties of zircon ceramics doped with different dopants. It is expected that the presence of defects in the zircon host structure introduced by doping, could lead to higher electrical conduction. The dopants used in this study were Y103, Fe103, MgO, Ybl03 and EU1O3. The study revealed that the electrical conductivity and the dielectric constant (s.) of doped zircon increased with increasing temperature, irrespective of the dopant. A good conductivity enhancement was observed in 10 mol% Y103 doped zircon and 10 mol% Fe203 doped zircon with the conductivity values 7.74 x 10-5 S em" (Er- 409;105 Hz) and 2.56 x 10-5 S ern" (Er-707; 105 Hz) respectively at 700°C. These conductivity values are about one order of magnitude higher than that of zircon without any dopant (3.83 x 10-6S em"). Since the Y203 doped zircon system showed the highest electrical conductivity, a broad range of Y203 dopant levels were investigated. This revealed that the conductivity increased with the dopant level up to 10 mol%. Further addition ofY203 was not effective to conductivity enhancement probably due to increasing the excess content of Y203 as a second phase. It was observed that the dielectric constant of 10 mol% Fe203 doped and 10 mol% Y203 doped zircon systems, having higher conductivity values, increased rapidly with increasing temperature. In contrast, the other systems having lower conductivity values showed only a slight increment in the dielectric constant with increasing temperature. The microstructures of the sintered ceramics were studied using Scanning Electron Microscopy (SEM)and Energy Dispersive X-ray analysis (EDX). It was evident from subsequent microstructural studies that the additive oxides ~03, MgO and EU203 were not substituted into the host structure of zircon and appeared as a second phase. As a result there was no conductivity enhancement due to doping of these oxides. In the case of Y203 ( y3+) and Fez03 (Fe3) doped samples, the most likely reason for the conductivity enhancement is that v" and Fe3+ ions get substituted into the host structure of zircon creating 02- vacancies to maintain the charge neutrality of the material.
A study on industrial hazards in desiccated coconut industry
(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Nandana, H. Y. A.; Werellagama, D. R. I. B.
Coconut products are the second largest agricultural export product in Sri Lanka after tea. Desiccated Coconut (DC) accounts for almost 40% of the total export revenues from coconut products. Sri Lanka is the second largest producer of desiccated coconut in the world (after the Philippines) and the production is still growing rapidly. Sri Lanka is estimated to produce 50,000 tonnes of desiccated coconut per year accounting for 40% of the world production. Most of coconut plantations and its related industries are located in the triangle of the three cities of Colombo, Kurunegala and Puttalam. Presently there are 64 DC mills in operation, of which around 50 are large-scale factories, processing over 100,000 coconuts per day. The remaining mills are medium scale; processing around 50,000 coconuts per day. Some of the existing DC industries significantly contribute to the deterioration of the quality of the environment. According to the 1993 report of Central Environmental Authority (CEA), desiccated coconut industry is the third major water polluter in Sri Lanka after natural rubber industry and concentrated latex industry. One coconut gives approximately 0.2 L of coconut water. Combined with wash water and sterilizing water, a factory processing 50,000 nuts/day discharges about 50m3 of wastewater per day. A characteristic wastewater cocktai' from a DC mill comprises COD 8000 mg/L, BOD 4000 mg/L, SS 300 mg/L, Nitrogen (nitrate, nitrite and ammonia) 50mgIL and Phosphorous 10mg/L. The pH value is around 5.0. Most factories discharge their untreated or poorly treated effluent to general watercourses, creating a significant pollution and problems for downstream users. Some DC mills had to be closed due to the complaints from the neighbors about odour problems. In some DC mills some treatment is attempted, using physical treatment methods like screening and oil separation. Since the strength of the waste stream is very high, physical treatment alone is not enough. Chemical treatment methods will create large amounts of sludge, which also have to be treated. Therefore the possibility of biological treatment was investigated and an aerobic bacteria mix named EM (effective microorganisms) was selected. The treatment process sequence identified in this study is screening, oil-separation, aeration, sedimentation, secondary aeration, secondary sedimentation and filtration. EM is added to both aeration tanks. The optimum volumes of EM to be added to the tanks are currently under investigation. Batch testing with EM shows 75% COD reduction by one aerator. With two aerators in tandem, it can reduce the COD values to comply with the Sri Lankan Standard for Discharge of Industrial Effluents into Inland Surface Waters (1990). The treatment process developed in this research overcomes the odour problem. To ensure the effluent will not have free EM, it is chlorinated before discharge into the polishing filter for the final treatment step.
A study on the developmental cycle of dactylogyrus intermedius in Gold -Fish ( Carassius Auratus)
(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Perera, U. F. R.; Rajapakse, R. P. V. J.; Arulkanthan, A.
Dactylogyrus intermedius (gill fluke) is a monogenean trematode known to cause heavy morbidity and mortality in gold-fish (particularly in young fry) in many commercial aquariums in Sri Lanka. Information on the clinical presentation of the disease and the life cycle pattern of D. intermedius infection in gold-fish under local conditions are scarce. Therefore, with a view of proposing measures to control this infection in Sri Lankan aquariums, the above mentioned aspects were studied. Four hundred gold-fish fry (age; 3-4 weeks), which were naturally infected with D. intermedius, was obtained from an aquarium in Colombo. After observing the clinical features, 50 randomly selected fry were sacrificed and gross lesions in the gills were noted. Ten infected fry were kept in a tank for 48 hours to determine the mean spawning rate. The rest of the infected fry were used to obtain eggs for life-cycle studies. Freshly spawned eggs (n=250) were incubated in de-chlorinated water at room temperature (26-29 °C) and the eggs were examined twice daily for larval development. In a subsequent experiment, two groups (A and B) of uninfected gold-fish fry (n=10/group) were kept in separate tanks and on Day 0 of the experiment freshly spawned eggs (250 eggs/tank) were added to each tank. On Day 7 of the experiment, fish from group A was removed from the tank and kept individually in 10 petri dishes and examined twice daily for the presence of freshly spawned eggs. Group B was transferred to a new tank on Day 7 of the experiment; thereafter one fish was sacrificed on every other day and skin scrapings and gills were examined for developmental stages. The common clinical signs observed in infected gold-fish fry varied but the salient features were widely opened operculum, rapid breathing, and crowding near the surface with gaping mouths. At necropsy, varying numbers of D. intermedius (range; 4-52) were found to be attached to the gills which were pale in colour with a heavy blanket of mucus. The mean spawning rate was 11 eggs/fluke/day and the operculated eggs (dimensions; 40-47.5 x 72.5-80 urn) sunk to the bottom of the tank after spawning. The larval development within the eggs was evident by 24 to 48 hours post incubation. Free swimming ciliated oncomiracidium (110 - 115 x 40 - 45 µm) emerged from the eggs by 2.5 to 6 days post incubation and the percentage of hatching was 85-90 %. Immature flukes were present on the skin and gills, whereas the mature flukes (112.5-137.5 x 312.5-337.5 µm) were attached either on the primary or secondary lamellae of the gills. The duration taken to complete the life cycle (eggs to eggs) at 26-29 °C was found to be 12-15 days. It is suggested that physical removal of eggs from the tank by bi-weekly siphoning off the sediment and coupled with a chemical treatment in the form of continuous immersion for a minimum period of 15 days would control this infection by disrupting the life cycle.
A technique for re-attachment of fractured incisor teeth fragments
(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Weerasinghe, D. D. S.; Wettasinghe, K. A.; Kato, J.
Traumatic injuries in the incisor region are common, especially among children and adolescents. Reattachment of natural tooth fragments is an important technique for restoring fractured teeth and provides advantages over resin-composite restorations and crowns. These include better aesthetics, maintenance of original tooth form and colour, minimal tooth loss, increased wear resistance, and thus improved function, with a sense of belonging to the patient. This report presents the use of composite resin materials for reattachment of fractured natural tooth fragments in maxillary and mandibular incisors. Modem technology has continued to improve the quality of composite resins and now they are increasingly being used in restorative dentistry. In spite of some drawbacks, such as polymerization shrinkage, incomplete conversion and cross-linking and water absorption, the survival rates of composite restorations have improved due to the improvements in the physical and chemical properties of the material. A case history of a 22-year-old patient who accidentally injured his maxillary and mandibular right central and lateral incisors is presented. All four teeth were fractured from the cervical margins of the crowns. Except the upper central incisor, all other fractured fragments were intact at the time of presentation. The patient brought the fractured central incisor dipped in water. In the upper lateral and lower central incisors, fracture lines extended 2mm below the cervical margin, palataly. After separating all intact fractured segments pulpectomy and root canal therapy was carried out for all four teeth. After removing pulpal tissues the separated tooth fragments were stored in a refrigerator in normal saline. After a three week of observation period an appointment was given for reattachment of the fragments. Gutta purcha was removed from coronal two thirds of the root canals. Suitable metal posts were selected and sandblasted. Root canal surfaces were etched with gel containing phosphoric acid (K-Etchent gel) for 10 seconds. After etching, adherent surfaces were washed and dried. ED primer was applied to the root canal surfaces and metal primer was applied to the metal posts and left for 60 seconds. Using a sponge excess primer was removed to prevent the primer from pooling inside the root canal. The primer was dried with a gentle flow of air. The mixed dual cure composite resin (PANAVIA F) was applied to the root canals and after applying a coat of mixed resin to the posts they were inserted into the canal quickly. Vibratory movements were used to prevent air entrapment during insertion of the posts. By using a small brush, excess resin was spread over the post head. It was subsequently cured for 20 seconds using a light source. The same procedure was followed in application of resin to the adherent surfaces of the natural crowns after enlarging the pulp chamber area to take up the post. Then they were fixed to the posts and light cured for 20 seconds. 0.5mm thickness of enamel was removed from the labial surfaces along fracture lines and they were replaced with matching light cured composite.
A test for detection of fomalin milk and milk-products
(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Fernando, C. P. L.; Horadagoda, A.
Formalin is a chemical preservative suspected to be added to milk and milk-products to increase their shelf-life. Sri Lanka Standards Institute prohibits its use in milk-foods due to its toxicity and thus screening tests need to be done routinely to ensure that the multitude of dairy products in the market are free of formalin. The methods available currently for the detection of formalin are either indicated only for raw liquid-milk, or are much too laborious and expensive to be used routinely. The objective of the study was to determine a simple, accurate, and a cost effective test to detect formalin in 'ready- to- drink' and raw liquid milk, yoghurt and curd (if directly added, or if indirectly applied by a formalin soaked tissue paper). Thirty two samples of curd obtained from Melsiripura in the North-Western province were screened to test the applicability of the method. There are a number of tests indicated for raw liquid-milk. Of these, Leach test was applied directly and Shiff's test was modified as Shiff's-Indirect and Shiff's-Direct. Measured amounts of formalin were added to liquid milk (both flavoured/coloured and raw), yoghurt and curd to obtain dilutions of 1000, 100, 20, 10, 5 and 2 ppm with a negative sample as the control. For each of these dilutions, the above mentioned three tests were performed repeatedly for 16, 16 and 10 times with samples of liquid milk, yoghurt and curd, respectively. Leach test and Shiff's-Direct test were performed for formalin dipped tissue paper and repeated 10 times. Leach test gives 100% sensitivity at 1000 ppm for liquid-milk (coloured and raw) at 20 ppm for yoghun and at 10 ppm for curd. It is not effective for the detection of formalin absorbed into a tissue paper. Shiff s-Direct method gives 100% sensitivity at 10 ppm for liquid-milk and at 20 ppm for both yoghurt and curd. This method can be used with 100% sensitivity for tissue papers dipped in a solution of formalin at a dilution of 1000 ppm. Shiff's- Indirect test can be used with 100% sensitivity at 10 ppm level for all three products tested. The study indicated that Shiff's-Indirect method is the most suitable and also a simple, cost effective test that can be applied commonly for the detection of formalin in 'ready- to- drink' and raw liquid milk, yoghurt and curd. It may be developed into a quantitative method by spectrophotometry or applied for other food products such as fish and fruits. The cost of this test is approximately Rs 4.50 per sample. Shiff's-Direct test can be applied to detect formalin if absorbed into tissue papers and the cost was found to be approximately Rs 2.00. The samples of curd obtained from Melsiripura did not contain formalin at a level of > 10 ppm.
A tested method for sampling and analysis of polycyclic aromatic hydrocarbons in combustion products
(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Karunaratne, D. G. G. P.
Much attention has been focussed on polycyclic aromatic hydrocarbons (PAHs) owing to environmental concerns and the health hazard associated with these compounds. They have been recognised as one of the largest classes of carcinogens known today. Even though PAHs can originate from natural processes such as volcanic eruptions and forest fires, anthropogenic activities have dramatically increased their concentration in the environment. Since combustion of organic compounds is considered to be the main source of man made PAHs in the environment, the measurement ofPAHs accurately in combustion products is important as far as regulatory and emission control aspects are concerned. The sampling and analysis of PAHs are formidable tasks for several reasons such as their existence in minute quantities in matrices and their association with many other compounds. In addition, they are present in combustion products in the gas phase and condensed onto the water vapour and particulates. Therefore, special techniques need to be adapted for the sampling and analysis of PAH. Although an ample amount of material related to the subject could be found in the literature, there is a considerable variation among the methods. Consequently, and also to suit the available facilities, a protocol for PAH sampling and analysis was developed and tested. The sampling of the PAHs was carried out using a sampling train constructed mainly with glass. It consisted of a probe, which had been constructed to meet isokinetic sampling, a glass fibre filter, gas conditioning unit consisting of a circulating water jacketed condenser and a water trap, resin trap, an organic solvent trap, a silica gel trap, an air tight pump, a flow meter, and a gas meter. The collected samples were extracted using organic solvents and then subjected to solvent exchange. The PAH fraction was separated using a simple silica gel column. The analysis was done using a Ge/MS system. A modifted Lee index was employed to confirm the identified compounds.
Aerated soaking of paddy for rice parboiling and its effect on effluent kinetics
(Unviersity of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Senanayake, S. S.; Basnayake, B. F. A.; Mowjood, M. I. M.
Parboiling is practiced to increase the milling performance and cooking quality of rice. The main steps in parboiling process are soaking, steaming and drying of paddy. Traditional cold soaking is one of the methods used for soaking in which the paddy is submerged in water for a period of 48- 72h. The effluent from this method is in poor quality and has the potential to pollute the environment, water bodies and lands. This study was carried out to find a solution to reduce the environmental impact of effluent release from parboiling process. The effluents (traditional parboiling method - T 1) from five mills in Anuradhapura were collected and the colour, odour, turbidity, temperature, pH, Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Solids (TS), and Total Suspended Solids (TSS) were measured. Alternatively two laboratory models were developed and tested for aerated soaking. In the first model (T 2) the water was trickled over the paddy at the rate of 1000ml/min and drained water was re-circulated to reduce the amount of water needed for soaking In the second model (T,) a charcoal filter was introduced before the re-circulation of water to study the effect of charcoal treatment in the effluent The effluent samples from 11, 12 and 13 were incubated at 20°C and Dissolved Oxygen (DO) was measured in 12h intervals for 5 days to calculate BOD values. DO was measured using Winkler titration method The rate constants were estimated from the BOD curve developed for the three treatments. Average temperature, pH, COD, TS and TSS values of the eftluent of T 1 were 38°C , 6.1, 2548 mg/l, 150 mg/l and 50 mg/l, respectively. The effluent from T 1 also had the highest mean BOD value (2452 mg/I) at the end of 5 days, unpleasant colour and odour though the degree of contamination varied among the mills These results indicate the potential of the effluent of the traditional method as a pollutant. Effluents of the laboratory models (T2 and T3) recorded much lower BOD values at the end of 5 days (356 and 128 mg/l, respectively) with no unfavorable colour or odour T3 recorded the lowest rate constant (0.07 per day) when compared with T, and T2 (0.28 and 0.15 per day, respectively). In the aerated soaking methods (T2 and 13) tested, water can be recycled. In addition, the soaking time needed to absorb water up to optimum moisture content was less in T2 and T3 compared to that of traditional method. Eating quality of rice was also observed to be high with the aerated models than with the traditional method. Power requirements and cost - benefit analysis have to be studied to improve the aerated soaking system in mills. Further studies are necessary to identify carbonaceous and nitrogenous demand in the BOD curves of the models considered Further understanding on the kinetics of effluent can lead to design more efficient aerated soaking and effluent treatment reactors.
An Investigation into Dairy co-operatives in the Batticaloa District
(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Jeyanantham, V.; Gunawardene, V. K.
One of the first priorities in a developing dairy industry is a stable, organized market that gives adequate returns to the farmer. The factor most likely to increase milk production steadily is a good selling price relative to the cost of production. The most widely acclaimed milk marketing schemes in the developing countries are the farmer-owned co-operatives, especially where dairying is based on small-scale farming as in India. Although collecting milk from a large number of small-scale farms seems an unorthodox way to run a dairy industry, it can provide a large volume of milk. The system also provides a valuable regular income to the poor village people. Experience also shows that the collection of the limited quantities of milk from the scattered small farms are best handled by co-operatives to improve the income of farmers and to provide processors and consumers with a regular milk supply. A data collection survey was carried out during March to November 1999 in the Batticaloa district to determine the role of the dairy co-operatives in the dairy industry. It was found that the district had six co-operative societies. Most of them were situated far from the farms. These co-operatives purchased milk from widely scattered suppliers and sold it to processing factories. However, the Bt/Livestock Breeders Co-operative Society that is located in the Batticaloa town was not involved in milk collection even though it had the second highest membership. The study revealed that the services provided by these co-operatives were unsatisfactory and the members could not get the services all the time. Also, most members felt that the extension services provided were inadequate. An important finding was the massive contribution made by the middlemen to the dairy co-operatives and it appeared to threaten the future of dairy farming in the Batticaloa district. In two of the co-operative societies, 40% and 72% of members were found to be middlemen, who supplied 64% and 83%, respectively, of the total milk collected by these societies. Dairy co-operative members faced several problems such as difficulties in obtair.ing loans, scarcity of grazing-land, delay of payments, low price for milk and having to travel a long distance to the collecting centres. They also faced problems of not being informed of meetings and other activities of the co-operative society. The co-operative society administration W:4S also confronted with problems. These included difficulties in recovery of loans, transport of milk, and non co-operation of members and veterinary officers. This study concludes that the dairy co-operative movement in the Batticaloa district is unsatisfactory and unsuccessful because of the limited participation of members in the dairy co-operative activities.
An Odontometric Study of the Permanent Molars in two Ethnic Groups in Sri Lanka
(University of Peradeniya, Peradeniya,Sri Lanka, 2001-11-16) Peiris, H. R. D.; Nanayakkara, C. D.
The shape and the size of the teeth are known to vary. Evolutionary anthropologists have highlighted that the size and the shape of the teeth change due to selective forces, technological and dietary changes during human evolution. These dimensions also furnish human biologists and clinicians with an insight into the genetic relation between populations and environmental adaptation. A study was undertaken to establish mesiodistal, buccolingual and occlusal dimensions of the permanent molars of the Sinhalese and Sri Lankan Tamil adult males. Eighty males belonging to the Sinhalese and Sri Lankan Tamil ethnic groups (40 Sinhalese and 40 Sri Lankan Tamils) in the age range of 20 - 35 were selected. Three generation pedigree was recorded for each individual in order to check the ethnicity. Teeth were selected for measurements only if they were morphologically normal and fully erupted, not noticeably affected by attrition and caries and not restored. Only individuals having the normal occlusion were included in the study. Measurements were obtained on the dental casts taken from each subject. The measurements included, mesiodistal and buccolingual crown diameters (MD and BL) of the maxillary and mandibular molars, MD and BL diameters of the trigonid and talonid (TRMD, TLMD, TRBL, TLBL) of the mandibular molars. All measurements were recorded to the nearest 0.01 mm. using a digital vernier caliper by one investigator. The means and SDs of the MD and BL crown diameters of the maxillary and mandibular molars, TRMD, TLMD, TRBL, and TLBL of the mandibular molars were computed. Differences between the means were tested for significance using the student's t- test. Mean values of all measurements of teeth were larger in Sri Lankan Tamils than in the Sinhalese. However, significant differences were observed for the MD and TLMD of the mandibular second molar tooth and MD of the maxillary first molar tooth between Sri Lankan Tamil and Sinhalese males.
An Oral Carcinoma in a Jaguar - A Case Report
(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Deepani, M. L. A. N. R.; Tilakaratne, W. M.; Alahakoon, J.
In Sri Lanka, oral cancer is the most common type of cancer among humans. In animals, prevalence/incidence rates of oral cancer are not available. Reported oral cancers in animals are scanty and little. No previous records of oral carcinomas in jaguars have been reported in Sri Lanka. An oral squamous cell carcinoma in a jaguar was diagnosed histopathologically at the Department of Oral Pathology, Faculty of Dental Sciences, University of Peradeniya. A biopsy sample was received from an 18 year-old jaguar reared in the National Zoological Gardens, Dehiwela, with a history of bleeding from the right side of the mouth. Intra- oral examination revealed a fleshy, sessile mass on the gum adjacent to the right upper premolars. The biopsy sample was subjected to histopathological investigations and immuno-histochemical staining. The histopathological features indicated that the animal was suffering from a moderately/poorly-differentiated squamous cell carcinoma.
Analysis of how to control the pollution due to wastewater from textile industry
(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Abeyarathne, W. G. N. S.; Karunarathne, D. G. G. P.; Herath, G. B. B.
The textile and garments industry is the largest industrial sector in Sri Lanka. Direct and indirect employments in these industries are estimated to be over 500,000. The textile industry manufactures finished cloth from imported raw materials. Manufacture of finished cloth from raw fibre (cotton and synthetic) involves 3 major operations as, spinning, weaving/knitting and finishing. Spinning and weaving are essentially dry processes and cause therefore relatively minor pollution problems. Significant pollution problems are, however, caused by the various finishing operations, including desizing, washing, scouring, mercerizing, bleaching, dyeing/printing and various types of final treatment processes. The finishing processes consume large quantities of water producing substantial volumes of liquid waste, which is a significant source of water pollution in Sri Lanka. The textile processing industry in Sri Lanka is probably the 2nd largest polluter after the natural rubber industries, which jointly generates a liquid waste load of about 45,000kg COD/day (Industrial pollution control guidelines from CEA). This wastewater contains various compounds, which are harmful for the aquatic environment and are toxic for human and animal in cases of ingestion or physical contact. Textile processing wastewater contain oil, dye and biodegradable organic compounds, which may cause anaerobic conditions in receiving surface waters, resulting in die off of fish and other water organisms and emission of foul odours. Wastewater treatment systems of textile processing industries generally consist of biological and/or physical/chemical treatment processes, or combinations of these processes. After these processes the treated water discharges to the nearby stream. The chemical and bio sludge resulting from the process are subjected to drying on a sand bed and then discharges without further treatment (normally used for land filling). The aim of this research is to analyse how to control and minimize the pollution due to this wastewater & sludge discharge. The production of waste from textile processing operations can be prevented or reduced by numerous different measures. Such measures include replacement of toxic process by less harmful chemicals, process modifications and good housekeeping practices. Similarly the sludge also can be analysed for the harmful substances and we can find methods to treat them.
Analysis of polycyclic aromatic hydrocarbons(PAHs) in ambient air
(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Karunaratne, D. G. G. P.; Jeyalalitha, E.
Most studies of emissions from combustion for energy generation have been aimed at abating inorganic emissions COₓ, NOₓ and SOₓ owing to the strict legislations to which these compounds have been subjected and because they are emitted in large amounts in comparison to organic emissions. Technical modifications to reduce inorganic emissions have affected organic emissions so that growing attention is being paid now to volatile organic compounds, particularly to polycyclic aromatic compounds (PACs) and, especially to polycyclic aromatic hydrocarbons (PAHs) owing to their carcinogenic character. Although there is no definitive legislation concerning PAH abatement, the Environmental Protection Agency (EPA) has fixed 16 PAHs as priority pollutants, the last of which was included in 1997. These compounds are as follows: naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, chrysene, benzo (a) anthracene, benzo( b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, indeno( 1,2,3-c,d) pyrene, benzo(g,h,i)perylene and dibenzo(a,h)antracene. It is expected that air quality would improve soon if PAH emission was controlled. The simplest member of the PAH family is naphthalene, a two-ring compound which can be found in the vapour phase in the atmosphere. Three-, four-, and five-ring compounds can also be found in both the vapor and particulate phases in the atmosphere. PAHs consisting of five or more rings tend to be solids adsorbed onto other particulate matter in the atmosphere. A widely recognized five-ring PAH compound is benzo (a) pyrene. Naphthalene is by far the predominant airborne PAH. Night time concentrations of naphthalene are greater than daytime concentrations because of the hydroxyl radial reaction mechanism which removes naphthalene from the atmosphere in daylight. As ring size increases, the effect of this removal mechanism diminishes. These gaseous- phase reactions are important because they also lead to the formation of nitro-P AHs which are direct acting mutagens. High volume air samplers equipped with polyurethane foam (PUF) adsorbent have been a standard device for monitoring semi-volatile organic compounds (SVOCs) in air for a number of years. In such samplers, air is drawn past a filter to retain particle-phase SVOCs and then past the PUF adsorbent to retain vopour-phase SVOCs. This sampling geometry has the potential to cause sampling artifacts, most notably "blow-oft" whereby SVOCs which are adsorbed on particulate matter in ambient air may be volatilized from the particles after collection on a filter medium, thus enhancing the apparent vapour-phase concentration. A second effect which may occur is "blow-on" whereby vapor-phase SVOCs in ambient air are adsorbed on the filter media or on accumulated particulate and/or organic matter on the surface of the filter media. This would result in an apparent increase in the particle-phase loading of the SVOC in question. It is important to note that both of these phenomena can occur simultaneously.
Analytic philosophy: A brief appraisal
(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Kalansuriya, A. D. P.
Analytic philosophers identify the very subject of Philosophy with an analysis of words, terms, notions, expressions, statements, etc.. Wittgenstein gave a new impulse to analytic philosophy with the radiant notion, namely, "A main source of our failure to understand is that we do not command a clear view of the use of words." This is a clear recognition of human failure together with a committed estimate of the ability to engineer solutions for problems that have befallen the best brain since the Greeks. "A clear view of the use of words." But, then, what does it mean? One has to note the nature of the discourse, that of the doctrine, that of the argument, etc. (to which Wittgenstein says 'language game') in which it finds expression that is its original home, in which alone it meaning. Two conclusions follow (i) that confusions, which occupy us do not arise. (ii) which are already there, can be dispelled. The implication being a therapeutic one reminds of a prescription for doing philosophy. That is, putting the word in its linguistic context and whole statement in its native context. But, then, how does one do this? By accepting and mastering analytic techniques. The resuIt: To bring words back from their metaphysical to everyday usage (L Wittgenstein, 'Phylosophical Investigations, 1953: 48e), implying that metaphysics does not have a logic of its own whereas other discourses have a logic of their own. Implied are "chains of reasoning" or "forms of life" in all discourses other than 'philosophy'; for 'philosophy' is not a discourse an analytic activity. Based on this concept of "chains of reasoning," one sees not only the nature of the discourse--science, religion, aesthetics, etc. but also the limits pertaining to 'truth' or 'falsity' of statements that come within first-order disciplines. This brings out the very base of Analytic phylosophy understood and practiced in the English-speaking world as a second-order discipline.

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