PURSE 1999

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Can DNA be Extracted from Tooth Pulp? a Preliminary Study
(1999-11-20) Gooneratne, Induwara; Mendis, B. R. R. N.; Amarasinghe, P.
Forensic identification is easy if an entire human body is available with minimal decomposition. Once decomposition has set in or when parts of the body are missing, identification becomes difficult or at times impossible using classical methods. In such situations DNA has proved to be useful for identification and increasingly, forensic studies utilize DNA profiles of individuals to establish identity. Of the many parts of a human body, the tooth which is composed of a highly mineralized tissue, survives most postmortem circumstances like decomposition, immersion in water, burial and fires that reach high temperatures. Enclosed within this hard tissue (enamel and dentine), lies the dental pulp, which consists of a specialized connective tissue with many types of nucleated cells. Thus, the dental pulp could be utilized as a source for the extraction of genomic and mitochondrial DNA, for purposes of forensic studies. This study describes a method for the extraction of DNA from Human teeth. Teeth and blood samples were collected from individuals who visited the Dental Hospital, Peradeniya. Non-carious teeth that were extracted for orthodontic purposes and blood samples of the same individuals were used for the extraction of DNA. The surface of the tooth was cleaned with distilled water and split longitudinally in order to extract the DNA rich pulp. It is possible to isolate and extract DNA from human tissues using Phenol-Chloroform method, Chelex-lOO method, using liquid Nitrogen etc. The pulp of the tooth was collected using pipettes, an excavator and a surgical syringe where necessary. In this study the DNA was extracted using the Phenol/Chloroform method. The pulp was taken into a 1.5 ml polypropylene tube. Equal amount of digestion buffer was added and incubated for 1 hour at 37°C. Furthermore, an equal volume of phenol- chloroform - isoamyl alcohol 25:24:1 was added and mixed. The suspension was centrifuged at 4000 rpm for 10 minutes. The top aqueous layer was aspirated and an equal volume of chloroform: isoamyl alcohol 24: 1 was added to the aspirate. Again the top layer was centrifuged and aspirated and 2 volumes of cold absolute ethanol and 1/10 volume of 3 M Sodium Acetate of pH 5.2 was added and left at - 20°C temperature to precipitate the DNA. The extracted DNA was visualized on an agarose gel, stained with ethidiumbrornide and viewed under UV light. In the gel, a smear produced by the DNA was found and a photograph was taken. It can be concluded that DNA from tooth pulp can be extracted using this method.
Basic Knowledge of Medical Ethics Among Dental Students a Preliminary Study
(Unviersity of Peradeniya, Peradeniya, Sri Lanka, 1999-11-20) De Silva, Mevna; Bannehake, B. M. H. S. K.; Gooneratne, Induwara; Mendis, B. R. R. N.
Medical Ethics deals with the moral principles which guide members of the medical profession in their professional dealings with each other, their patients and also the state. Dental surgeons registered with the Sri Lanka Medical Council are expected to abide by the principals of ethics accepted and practiced by the Sri Lanka Medical Council The doctor- patient relationship is the central focus of ethics in Medicine and Dentistry Reasons for this are that ethics has to do with actions involving help or harm to others. In Medicine and Dentistry the doctor is the agent and the principal recipient is the patient. Control of the relationship results from the power of the doctor, and ethical standards help guide this power. Most interactions in the health care delivery system have over a long period evolved, some aspects of these interactions are the, doctor- patient relationship providing continuity, privacy, development of mutual responsibility and others. There are rapid changes in the extension of this relationship that bear on these interactions in significant ways making it more complex, like third party payers, insurance, policies of professional groups, private practice, medical institutions, etc. The image of doctor-patient relationship has to be well established and improved in our country for well being of our society. The main objective of this study is to assess the level of basic knowledge of medical ethics among dental students who will practice in various capacities after qualifying. Another objective is to formulate the medical ethics teaching programme in Faculty of Dental Sciences for the dental students after assessing their basic knowledge. A sample of 126 dental students in clinical and preclinical years were randomly selected and a questionnaire was distributed in a classroom in the presence of the investigator. Results were analyzed subsequently. The resuIts show that 34% students have had lectures on Medical ethics, 65.9% have not had such lectures 0% of students have faced " ethical dilemmas" . 27% students have kept the question blank 9.5% revealed that they are competent to diagnose an ethical dilemma, while 57 1% students revealed thev were not competent, 33.3% kept that question blank 55.5% students thought they need professional instructions to tackle ethical dilemma, 3.96% thought they do not need professional instructions. while 40.5% students kept the question blank 49.5% of students had heard about the Hippocratic Oath while 37.1% had not heard about it. 13.3% kept the question blank In their opinion 88.6% thought they need to learn medical ethics as dental students, while 11.4% kept the question blank 79.2% thought it is necessary to update the knowledge ethics, 5 7% said it is not necessary to update while 18.0% kept the question blank 55% thought patients should be aware on their basic medical rights while 7% thought patients should not be aware while 38% kept the question blank
Cardiovascular responses to experimental chewing
(Unviersity of Peradeniya, Peradeniya, Sri Lanka, 1999-11-20) Kumarasiri, P. V. R.; Pallegama, R. W.; Sitheeque, M. A. M.
Cardiovascular responses (CVR) to general muscular activity in the human body have been extensively investigated, but negligible attention has been paid to such responses to jaw muscle activity though it is reasonable to expect similar changes in response to protracted activity of masticatory muscle such as continued chewing The aim of this study was to ascertain the cardiovascular responses to chewing activity in young healthy volunteers and to compare the CVR of the chewing of gums of two different consistencies. In addition to this, variation in the time-point for the muscles of mastication in healthy adults to become fatigued was studied. Ten healthy men ranging in age from 22 to 28 performed two chewing sessions: chewing a hard gum and chewing a soft gum on two separate days. They were asked to chew on their most convenient side at a normal pace (cycles/min). Heart Rate (HR) systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured 15 min, 10 min and 5 min before the commencement of chewing. Then each subject was asked to chew gums for 15 min. and HR SBP and DBP were measured at five-minute intervals during this chewing period. Then they were asked to stop chewing and to have the gum inside the mouth for ten minutes as the HR, SBP and DBP were recorded at two minutes intervals. During the chewing period, time taken for them to feel any kind of discomfort or pain indicating the onset of fatigue was measured. Mean baseline HR and SBP of two sessions were not significantly different (P <0.2 and <0.65). With the soft gum mean HR increased by about 14 beats/min. mean SBP by 10 mmHg and mean DBP by about 9 mmHg. With the hard gum mean HR increased by 14 beats/min, mean SBP by 10 mmHg and mean DBP by 10 mmHg These changes were highly statistically significant (P <0.0001) Difference of increases in mean HR. and mean SBP with chewing of soft and hard gums was not statistically significant (P < 0.16 and < 0.47) But the difference of mean increases in DBP with two types of gums is marginally significant (P < 0.025) which is not totally valid as the mean baseline DBP of two sessions were slightly different During the recovery both SBP and DBP drops down to the resting level within ten minutes but HR tend to be slightly elevated even after 15 minutes. These CVR with both types of gums poorly correlate with the chewing rate and comfortable time of chewing, which may be a result of the small sample size. The results of this study reveal that chewing activity is associated with general cardiovascular responses. Negligible difference of cardiovascular responses (CVR) between soft and hard gums may be attributed to the fact that the consistencies of these two types of gums are not significantly different Further studies are essential to understand the nature of the association between chewing activity and CVR.
Computer program for highway designs
(Unviersity of Peradeniya, Peradeniya, Sri Lanka, 1999-11-20) Gnanasunthar, G.; Kirunthikaran, K.; Edirisinghe, A. G. H. J.
Two major areas in highway designs are pavement designs and geometrical designs. Pavement design involves with deciding the thickness of different layers of materials between the existing ground and the surface of the road. Geometrical designs involve with finding proper alignment of different road sections in the horizontal plane and vertical plane to provide safe and comfortable drive. For both pavement and geometrical designs, standard design charts are available according to different standards such as British, American, Australian, etc. Transport Research Laboratory in England is carrying out wide range of studies to improve roads in tropical countries like Sri Lanka and prepare documents to assist design works. In the present study two such reports namely Overseas Road Note 31 for pavement designs and Overseas Road Note 6 for Geometric designs were used. The computer program developed in this study can handle pavement designs using Overseas Road Note 31 and Road Note 29 and Geometric designs (only curve designs) using Overseas Road Note 6. The purpose of this program is not only for carrying out designs but also to use as a teaching tool for above two designs. All the design charts are included in the program and available for reference and all the intermediate steps in design procedures can be visualized. Help facilities are provided and the data entering is user interactive and user friendly. It has demonstrations about above two design techniques and some other topics related to highway engineering.
Characterization of aspartic proteinase inhibitor from Spondias Pinnata
(Unviersity of Peradeniya, Peradeniya, Sri Lanka, 1999-11-20) Kumari, H. M. P. S.; Athauda, S. B. P.; Perera, P. A. J.; Wickramasinghe, A.; Takaashashi, Kenji
Study of natural inhibitors of aspartic proteinases have become very important and essential. They were identified as very important therapeutic target points in the control of AIDS, Malaria and Hypertension. In this study potential inhibitorls of aspartic proteinases were isolated and partially characterized from Spondias pinnata. Fresh stem bark of Spondias pinnata was ground at room temperature and at -70 °C by using liquid Nitrogen. Crude extract of powder was prepared in H20. Assay procedure to determine inhibitory activity of aspartic proteinase was developed by using porcine pepsin as the enzyme and denatured hemoglobin as the substrate. Percentage inhibitory activity of crude extract prepared by grinding at different temperature did not differ significantly. Inhibitory activity of crude extract was not changed significantly during incubation at 37°C and at cold temperatures. This suggests the relative stability of inhibitory constituents in crude extracts at room temperature and subsequent studies were done at room temperature. But extract prepared from oven drying lowered activity compared to the fresh sample. This suggests the less stability of constituents in crude extract at higher temperatures. 60% of the inhibitory activity of crude extract was lost during dialysis against a membrane with molecular cut off point of 12,000 Da. But 100% of inhibitory activity was recovered by using a dialysis tube with cut off point of 3000. This result suggests that the inhibitory molecules have molecular weights between 3000-12.000. The inhibitor was partially purified using Diethyl amino ethyl cellulose-52 chromatography, Ammonium sulfate precipitation and Q sepharose chromatography. In DEAE-52 chromatography, inhibitor molecules were eluted with linear gradient of 0.1 M NaCI in 0.02 M phosphate buffer, pH 7.0. Inhibitory activity was detected in 2 peaks eluted at 0.2 M, 0.4 M NaCI suggesting the presence of two inhibitor molecules in the crude extract with different charges. pH stability of inhibitor was analyzed by incubating the crude extract at different 'pH's ( pH 2.0, 3.5, 4.0 and 5.0) and determining remaining inhibitory activity. Relatively higher stability of inhibitor at acidic pH was observed. Further highest pepsin inhibitory activity was observed at pH 2.0. Purification and further characterization of the two inhibitory molecules are in progress to elucidate the structure of the inhibitors.
Bilayer Actuators(Artificial Muscles) Based on Polypyrrole
(Unviersity of Peradeniya, Peradeniya, Sri Lanka, 1999-11-20) Vidanapathirana, K. P.; Careem, M. A.; Dissanayake, M. A. K. L.; Skaarup, Steen; West, Keld
Various conducting polymers, including polypyrrole (PPy), undergo significant dimensional changes upon electrochemical doping (oxidation) and dedoping (reduction). These changes are linked with the movement of ions and solvents in and out of the polymer during those processes. The conformational changes occurring here are reversible and it has been suggested that this behaviour can be applied in a range of devices such as electrochemically driven mechanical actuators (artificial muscles), micro-structures. These artificial muscles are termed as electrochemomechanical actuators since they work with electric pulse which generate the electrochemical reaction ultimately converted into mechanical energy. In this work, we report about the fabrication of a bilayer artificial muscle with conducting polymer as active layer and a non-conducting polymer as the passive layer. Force measurements were done using the bending beam method, which was used to study the volume changes in the conducting polymer phase in bilayers. Preparation of the artificial muscle was done by electrochemically polymerizing a pyrrole film on a 25µm thick polyimide film ( size 20 x 5 mm) which was coated with 250 Å gold layer to get electrical contacts. Polymerization of pyrrole was done in an aqueous solution containing 0.05 M pyrrole and 0.05 M sodium dodecylbenzenesulfonate (SDBS). Force measurements were done using a microbalance simultaneously with cyclic voltammetry in an aqueous electrolyte of 0.1 M NaCI04. To examine the effect of the film thickness and the polymerization current density on the force, films were prepared with different current densities and with various thicknesses. PPy films were electrochemically deposited on the quartz crystal microbalance electrode to understand the mass change during oxidation and reduction of these films. The force measurement results showed that the films made with higher current densities have larger forces than the films made with lower current densities. They also clearly demonstrated that with the increment of the PPy film thickness, the resultant force showed an increasing trend. When the force. measurements are compared with cyclic voltammetry, it is possible to conclude that the force changes are associated only with main peaks of the cyclic voltammogram. The other interesting feature is that most of the force changes occur in a narrow potential window, which is an advantage in the applications. The results obtained with quartz crystal microbalance showed that during oxidation and reduction 10-20 water molecules co-intercalated to PPy/DBS film with each cation move in and out.
Computer based authoring-an electronic book version of the prospectus of the Faculty of Agriculture
(University of Peradeniya, Peradeniya, Sri lanka, 1999-11-20) Ariyaratne, A. R.
An attempt was made to publish an electronic book version of the Prospectus 1998-2002 of the Faculty of Agriculture, University of Peradeniya. The authoring tool known as AUTHORWARE PROFESSIONAL was used to develop this application. AUTHORWARE PROFESSIONAL 3.5 version is an icon based object oriented programming tool with facilities for hypertext, animations and multimedia applications. The information given in the printed version of the prospectus was rearranged as pages according to the topics. Each page giving specific piece of information is assigned to an icon. The resulting file from structuring of pages and arranging of information was then packaged to produce an executable file. In packaging, the option of Windows 95 and NT gives a file for users who do not have RunA3W application software. The pages containing required information can be accessed or opened by selecting topics given in the Table of Content which appears after introductory pages. Graphics related to the information in various pages have been included. This electronic book can be stored in a single 3.5" HD floppy disk as a compressed file and can be distributed to users instead of printed version. It helps in reducing the use of resources and in cutting down of printing expenses. In addition, the compressed file can be made available as a down loadable file under the faculty web page. The electronic book version of the faculty prospectus is a simple presentation of some of the capabilities available with authoring tools. In applications where use of audio, video, animations and interactions can be incorporated into publications. Therefore, this exercise is expected to create awareness for development of computer based material that can be used in education, training, advertising, etc.
Analysis Tood for Steel-Concrete Composite Frames
(Unviersity of Peradeniya, Peradeniya, Sri Lanka, 1999-11-20) Burgess, I. W.; Davison, J. B.; Dissanayake, U. I.
In its simplest form, composite frames of the sort considered in the present research work comprise a bare-steel frame of H-section columns supporting I-section beams laid out in the typical primary and the secondary manner, supporting an overlaid composite floor deck. The overall structural behaviour of the composite floor deck system divides naturally into two phases. During the first phase called 'construction stage' the profiled steel sheeting alone carries the weight of wet concrete, workmen and tools. The second stage of behaviour may be identified when the concrete slab interacts with the supporting beam and develops the composite action in the transverse direction with respect to the spanning direction of the profiled steel deck. This paper describes the mathematical formulation of the two-staged computer program, which has been developed by the first author based of the Finite Element Method of analysis. The program is capable of taking into account both geometric and material non-linearity, and can simulate the response the structure during the entire history of loading. The first module deals with the construction stage behaviour, using two different types of finite elements, namely the steel only beam-column element and the steel-to-steel semi-rigid connection element. The stains and rotations undergone by the bare-steel frame during construction is incorporated into the second stage of the analysis by programming the second module to read the output of the first module. The module to simulate the composite beam behaviour essentially consists of two additional finite elements, namely the composite beam element and the composite beam-to-steel column connection element. The former is capable of modeling the inherent but often neglected partial-interaction between the steel beam and the composite floor slab, by superposing the effects of curvature of cross-sections due to bending into the difference between the horizontal displacements of the centroids of steel and concrete sections. Further, it is capable of modeling the orientation of the metal deck and also the effect of continuation of reinforcements over column supports. Considering the fact that the joint and frame behaviour are more interdependent in composite than in bare steel construction, the composite beam to steel column connection is modeled as a 'macro-element' by integrating four different finite elements. Those elements were to take into account the steelwork connection flexibility, column web shear deformation flexibility, flexibility of the reinforced concrete slab zone and the flexibility of shear connectors between the steel beam and the concrete slab. The validation carried out clearly indicates that the results produced from the computer program are generally in good agreement with corresponding test results. This is applicable for the full loading history, including construction and composite stages. In particular the comparisons made against the test NR3 indicate very good agreement not only in terms of load-deflection but also on load rotation and load-bar strains. Some comparisons made with the initial static test results from the eight storied full scale testing building at BRE test facility at Cardington are also included.
A comparison of larval feeds and the effect of sun light on theg growth of guppy (Poecillia Reticulata )
(Unviersity of Peradeniya, Peradeniya, Sri Lanka, 1999-11-20) Chamila Kumari, Y. A. A.; Edirisinghe, Udeni
Guppy (Poeillia reticulata) is the most widely distributed and firmly established aquarium fish in the world. The efficient management practices as well as the balanced larval feeds have a direct effect on the exporting quality. Three larval feeds were tested for growth and survival of guppy fry. Artemia salina eggs were hatched using 28-30 ppt saline water kept at 27 °C for 24 hours. Micro- worms (Anguillula silusiae) were cultured on bread and Soya flour mixture. A dry pelleted feed was formulated using intestines of layer chicken, shrimp head meal, tilapia head meal and Soya flour as protein sources. CRD with three replicates was used as the experimental design. Day old guppy fry were introduced to each tank at a stocking density of 64 fry/m². They were fed twice a day at 100g/10,000 fry. Weight gain was measured at 7-Day interval. Water quality parameters were recorded at 4-Day interval through out the experimental period. The effect of sun light on the growth rate, survival and colour development was determined by keeping one treatment exposed to the sunlight while the other unexposed. Post larvae fed with artemia and micro worms showed significantly higher (P0.05) in the three treatments and the values were within the tolerable range for guppy. Fish exposed to sun light showed significantly higher growth (P<0.05), and more attractive colour patterns. Fecundity was found to be directly related to the body weight. Results revealed that hatched artemia as well as micro-worms could be used as a larval feeds for guppy. After the first 14 days, formulated feed could be used to achieve higher performance. It could be concluded that sun light has a favourable effect on the growth rate development of attractive colour patterns, healthiness as well as fecundity.
An amperometric sensor for the detection of 3,4-DPA ( Propanil)
(Unviersity of Peradeniya, Peradeniya, Sri Lanka, 1999-11-20) Navaratne, Ayanthi N.; Hafil, A. M.
N-(3,4-dichlorophenyl) propanamide (3,4-DPA) is used for selective post-emergence control of grasses (Echinochloa) and broadleaf weeds in cultivated rice in Sri Lanka. 3,4-DPA is highly toxic (inhibit photosynthesis) to most leaf plants and relatively non-toxic to the tolerance plants which contain the enzyme acylamidase. The enzyme acylamidase converts the substrate 3,4-DPA in to 3,4-dichloroaniline and propionic acid as metabolic products. 3,4-DPA is only slightly soluble in water and highly soluble in most common organic solvents. The acute oral LD50 word of technical propanil for rats is 1384 mg/kg, Glassy carbon electrodes coated with stearic acid (1% w/v , CH2 Cl2) provide a steady state amperometric sensor (at +0.70 V) for the detection of 3,4-DPA in 0.1 mol dm-3 phosphate buffer (pH = 7) as the supporting electrolyte. The mixture (1: 1 (v/v)) of water and ethanol was used as the solvent to dissolve propanil. Dependence of the cyclic voltammetric behavior of the pesticide and expected metabolic products was also carefully investigated. The linear dynamic range of the sensor for 3,4-DPA is from 1.0 x 10-4 to 5.3 x 10-3 mol dm-3 with minimum detection limit of 2.0x10-5 mol dm-3 (S/N =3). The coefficient of variation of the sensor response is 4.8%. The proposed method could be extended to detect 3,4-DPA which is present in environmental samples.
Bovine Beta-Lactoglobulin: The Role in Cow Milk Allergy in Infants
(1999-11-20) Horadagoda, A.; Hemamala, H. G. I. K.; Athauda, S. B. P.; Wijekoon, A.
Hypersensitivity to cow milk proteins is frequently observed during infancy and is believed to be an antigenic response to milk proteins that are absorbed through the immature intestinal mucosa. This hypothesis has been verified by identifying the proteins following in vitro digestibility of milk and determining the presence of such proteins in the serum of infants with cow milk allergy. In Sri Lanka, over 80 per cent of milk is consumed in the form of powdered milk in contrast to other countries where fresh milk is popular. The high keeping quality, availability, and the popular notion that powdered milk is less of a health hazard compared to fresh cow milk has led to increased powdered milk consumption. Fresh cow's milk, human milk and six cow milk formulae were subjected to in vitro proteolytic digestion in pepsin (1%) at pH 2 and trypsin (1%) at pH 8. Following the initiation of the in vitro digestive process, aliquots were collected at 0,0.5, 1,2,3,4, 6 and 24 hour and subjected to SDS-PAGE. Protein analysis by SDS-PAGE indicated that most cow milk proteins were completely digested in 4 hours but beta-lactoglobulin remained undigested even after 24 hours. Human milk is devoid of beta-lactoglobulin. All human milk proteins were completely digested by the proteolytic enzymes. Immunoblotting studies using rabbit anti-bovine beta-lactoglobulin indicated the presence of bovine beta-lactoglobulin only in the sera of infants with cow milk allergy and not those individuals without an allergic reaction despite the consumption of cow milk. Beta-lactoglobulin was not present in the serum of infants on human milk. The results indicate that the cow milk whey protein, beta-lactoglobulin is poorly digested and may play a role in the hypersensitive reaction in infants following its entry into circulation.
Deforestation and Degradation forested landscape: a case of Mahaweli systeme "C"
(Unviersity of Peradeniya, Peradeniya, Sri Lanka, 1999-11-20) Mendis, T. Indrasena
Deforestation and degradation of forest fragments and forest corridors in the planned agricultural landscape can be seen as an unsustainable way of maintaining agricultural resource base because this can leads to soil erosion thereby silting the regulatory reservoirs, canals and vast tract of paddy fields in the region. The end result of this is declining productivity and sinking fortunes for the settlers in the new colonies. However alternative suggestion is that the deforestation for expanding cultivation create new income earning opportunities and ameliorate income of the economically marginal sections of the settlements. This is a critical landscape management issue confronting new and old planned agricultural settlements of Sri Lanka. It is to fill this gap the present study focus on what is happening to the forest fragments and corridors in the project area of system 'C' and what forces are responsible for this process. The spatial scope of the study covers the project area of system "C" which is one of the fourteen settlement and irrigations systems of the Mahaweli development programme. Three study localities were selected to represent the system under study. The geographic origin and the method of settler selection provided the justification for the selection of units. The temporal scope covers a period of sixteen years from 1982 to 1998. The 1982 represent the initial year of settler colonization while 1998 constitutes the year in which fieldwork was conducted. The study is entirely based on the qualitative methodology as the pragmatism informed the major theoretical assumption of the study. Accordingly three methods were used to collect data. They included labour intensive narrative interviewing, participatory observation and the consultation of the published and unpublished sources. The findings shows that the majority of forest fragments and corridors, set aside as reservations, have now been converted to residential areas and chena cultivation. This has been made possible by encroachment and allocation to the member of second generation by the Mahaweli authority. It is also observed that the existing forest fragments have subjected to serve logging for commercial and household purpose. The analysis of data points to the inference that settlers struggle for survival in a resource poor environment has become the major cause for deforestation's and degradation of forested landscape in the new Mahaweli settlers. The widespread poverty, manifested in different forms, provide the impetus for seeking survival strategies leading to the removal of very important landscape characteristic -forests.
Biochemical Interactions in Shot-Hole Borer Infestation of Tea
(Unviersity of Peradeniya, Peradeniya, Sri Lanka, 1999-11-20) Kumar, N. Savitri
Shot-hole borer (SHB) beetle (Xyleborus fomicatus) bores galleries in tea (Camellia sinensis) stems and exists in symbiotic association with the ambrosia fungus (Monacrosporium ambrosium). SHB infestation of tea results in a loss in yield of the valuable leaf and the economic loss is felt mostly in high yielding fields planted with clonal tea. We have been studying the biochemical interactions between the SHB beetle, the tea bush and the ambrosia fungus in an attempt to develop a biochemical method for control of SHB. For this purpose a tea clone susceptible to SHB attack, TRI 2025, and a more resistant clone TRI 2023, were selected for our study. Host plant chemistry is known to influence the susceptibility of cultivars to microbial pathogens and insect predators. Secondary metabolites such as alkaloids, sterols, saponins and phenolics, as well as primary nutrient chemicals such as carbohydrates and amino acids play an important role in plant-fungal interactions and plant-herbivore interactions. Our studies show that the accumulation of caffeine, the major alkaloid found in tea, may be a defence mechanism of the tea plant. Caffeine was shown to have an inhibitory effect on the fungus, to delay the onset of the different developmental stages in the life cycle of the beetle, and to significantly reduce the number of emerging females in laboratory culture media. Caffeine is not toxic to the adult beetle but appears to have an ovitoxic effect. Polyphenols, which are important constituents of tea, were found to reduce the inhibitory effect of caffeine on the beetle. Activation of phenolic biosynthesis was indicated by an increase in phenylalanylammonia lyase (PAL) and polyphenol peroxidase (PPO) activities in beetle infested stems of both clones. However PAL and PPO activities were higher in the more susceptible TRI 2025 clone, which also has a higher content of phenolics. Caffeine--polyphenol interactions probably reduce the inhibitory effect of caffeine, and could also account for the in vivo tolerance of SHB to the relatively high concentrations of caffeine found in tea stems. Studies of neutral sugars showed that the development of ambrosia fungus as well as SHB was influenced by the relative proportions of glucose and inositol in the culture medium. Glucose and inositol in the ratio 5:1 (as found in susceptible TRI 2023 clone) were found to be more favourable to the development of both the fungus and SHB. Chitin, a linear polymer of β-2,4-linked-N-acetyl-D-glucosamine, is a constituent of fungal cell walls and the exoskeleton of arthropods. Organisms composed of chitin produce chitinases which do not occur naturally in plants. But plants may produce chitinases as a defence against microorganisms and insect predators. Chitinase activity in tea stems was found to be less in the susceptible TRI 2025 clone than in TRI 2023, and was significantly lower in beetle infested stems from both clones. Therefore either SHB beetle or the ambrosia fungus apparently has the ability to suppress the activity of this enzyme.
Comparison of the behaviour of electrochemically and chemically synthesized polyaniline
(Unviersity of Peradeniya, Peradeniya, Sri Lanka, 1999-11-20) Chandrakanthi, R. L. N.; Kareem, M. A.
It has been reported that polyaniline (PANI) can be synthesized by two principal methods; the direct oxidation of aniline by chemical oxidant (PANI-C) or by anodic oxidation on an inert electrode using electrochemical methods (PANI-E). However, the electrochemical method has an advantage of the resulting polymer does not contain contaminants from oxidative agents which are necessary for chemical synthesis. In addition, PANI can be obtained as a conductive film upon the electrode surface in the electrochemical method. The electrochemistry of PANI is more complex than that of other conducting polymers. Here the redox reaction involves the change of complete reduced state to fully oxidized state. The conducting state varies with applied potential and pH of the medium. Therefore conductivity depends on two variables; the degree of oxidation and the degree of protonation. The electrochemically prepared PANI films, which are conducting, can be cycled between oxidized and reduced states. Also thicker film can be prepared and peeled off from the electrode surface to get a free-standing, electrically conducting film. The strong adherence to the inert electrode of PANI has been the basis for detailed electrochemical studies. But the chemically prepared polyaniline doesn't adhere to any of electrode material. Therefore, electrochemical characterization of chemically prepared polyaniline has limitations. In addition, most conductivity measurements reported were made ex-situ with chemically prepared samples. Therefore, it was considered of interest to obtain electrochemical properties and in-situ conductivity of chemically and electrochemically prepared PANI films. In this study, the electrochemical behaviour of chemically and electrochemically synthesized polyaniline films has been investigated in aqueous functionalized acid solutions. Cyclic voltammograms of both films are almost identical. PANI films obtained by these two processes were compared with respect to their conductivity and stability at electrochemical treatment. A steady loss of electro activity occurs for PANI in acidic media during continuous cycling, indicating the total charge storage in PANI film is decreasing with the number of cycles. Conductance results of PANI indicate that there are three electrochemical forms; the reduced form which is insulating, the partially oxidized form which is conducting, and the fully oxidized form that is also insulting.
A design of low cost working model of wind turbine for battery charging purpose
(Unviersity of Peradeniya, Peradeniya, Sri Lanka, 1999-11-20) Obeyesekara, B. R. K.
The paper discusses that how to make a cost effective wind battery charger for rural community. Wind battery chargers are becoming popular among the rural communities as they can generate electricity capacity of which can be vary from 50 watts to 250 watts. As it is shown in the studies that power generated by the wind battery charger directly proportionate to area which is swept by the rotor blades of the wind turbine. In other words to increase the power out put, it is necessary to increase the radius of the wind blades. Subsequently increasing the overall size of the wind rotor, which is needed to be optimized with a base function of, cost analysis. Two-blade designs of wind battery chargers are the most cost-effective designs among the wind energy converters for battery charging. And also it is essential to have three-blade design to minimize the vibration to increase the overall plant efficiency relative to Blitz criteria. The faculty of engineering has designed a low cost-wind energy converter for battery charging purpose with the help of computer simulation. Airfoil of the wind blade is selected from NACA airfoil designs. Rated wind speed is taken; as 5 m/s, Furling is 18 m/s. Diameter of the wind blade is 3.2 m. Angle of attack is taken as 17 degrees. Speed ratio of multiplication is 10: J .And Hub of the wind rotor is designed in such away to hold the blades at Constant pitch. Materials for wind blades are used as treated wood planks and components such as hub. housing of multiplicator, cover & rudder of the plant are made out of waste materials of steel and other metals. Cost per l Ou-watt plant is approximately Rs. 48000.00. This is 1/3 rd of the cost reduction of available wind battery chargers. Assemble of wind energy converter for battery charging is fabricated in the faculty of engineering and made several trials to investigate the behavior of the plant according to different wind climates. Below: Assembling process of the wind energy converter.
Design of the campus network for University of Peradeniya
(Unviersity of Peradeniya, Peradeniya, Sri Lanka, 1999-11-20) Ratnayake, K. B. N.
The University of Peradeniya campus network is the largest fiber optic computer network to be established in the country. It is a hierarchical network design based on the multi-layer campus network model having three layers: access layer, distribution layer and the core layer. The technology used for the network is Fast Ethernet/Ethernet with provisions for future upgrades to Gigabit Ethernet. Network switches are used at the core and distribution layers while the access layer uses switches for about 95% of the nodes and shared hubs for the rest. Supported protocols on the network include IP and IPX. Fiber optic cables are used in the links at the core and distribution layers while fiber-optic and copper unshielded twisted pair (UTP) cables are used at the access layer. The access layer, which is at the bottom of the hierarchy consists of the department and building level networks at the various locations within the campus. Layer 2 switches and shared hubs located in the individual buildings and floors and UTP cabling is used to interconnect over 1500 network nodes. In multi-storied and large buildings where it is necessary to use more than one switch, the switches are interconnected using fiber-optic cable. All access layer switches are Ethernet (lOMbps) switches with Fast Ethernet (lOOMbps) uplinks. The distribution layer of the campus network includes the inter-building networks of the faculties of Engineering and Science, Main Library building and the Senate building. Layer 3 Fast Ethernet switches are used for the Engineering and Science faculty networks while Layer 2 Ethernet switches are used elsewhere. Fiber-optic cables are used for interconnections in this layer. The core layer of the campus network consists of a Layer 3 Fast Ethernet switch. The core switch interconnects the distribution layer networks at the faculties of Engineering, Science, Arts, Medicine, Agriculture and Veterinary Science, Dental Science as well as the Senate Building and the Main Library building. The core switch also has a separate link to the common campus network resources in the server farm physically located in the Faculty of Engineering. The server farm includes common campus network resources such as Electronic Mail servers, World Wide Web servers, network management stations, access router connecting the campus network link to the Internet via LEARN (Lanka Educational and Research Network), and the dial-in router which provides access to the campus network through telephone lines. The interconnection medium used in the core layer is fiber-optic cable. Combination cables of Single-mode and Multi-mode optical fiber is used for all locations. Although multi-mode fibers would be sufficient for Fast Ethernet connections to the faculties of Engineering, Science, Agriculture and Veterinary Medicine, Medicine and Dental Sciences, single-mode fibers will be used make future upgrades to Gigabit Ethernet possible. The use of network switches at all the three layers also make it possible to use the Virtual LAN (VLAN) technology to provide location-independent LANs, improved network security and manageability.
A case study of water quality modelling in urban streams
(Unviersity of Peradeniya, Peradeniya, Sri Lanka, 1999-11-20) Weerakoon, S. B.
Urban streams receive more and more wastewater with the population growth, urban migration, industrial development and this results in the decrease of the environmental quality of the aquatic environment at an alarming rate specially in developing counties like Sri Lanka. Thus, maintaining water quality of urban streams to the desired standards is essential for health, bio-diversity preservation etc. through controlling waste water inflows with an understanding of the waste water assimilative capacity of the stream. A water quality model which describes the water quality parameters quantitatively along a stream is therefore an important tool in the planning of stream restoration schemes and also in the assessment of the influence of water quality changes brought by siting a new wastewater source. The present study has developed a one-dimensional, computational water quality model applicable for un-eutropic streams. The governing equations for the steady, stream water quality model are mass balance equation coupled with single-first order kinetic equation, 0=-U(dL/dx)-KL, for contaminant (N, P, BOD) concentrations and O=-U (dc/dx)- Kd L BOD exp(-K, x/U)+Ka(cs -c), for dissolved oxygen concentration where KN, KP, KBOD are decay rates, Ka. Kr Kd are aeration, total loss and deoxygenating rates. U is the stream velocity, Cs is the saturated DO concentration and x is measured from the upstream [Please refer to the downloaded abstract for the correct symbols]. The model was applied to the Meda-Ela (Mid Canal) which originates from the Kandy Lake and falls into the Mahaweli River at Getambe to assess the influence of alternate restoration proposals. By a field survey, wastewater sources were identified and pollutant loads received by this highly polluted canal along its path of about 4 km were quantified. It receives pollutants directly from restaurants, open markets of vegetables, fish, meat in the town, railway and bus stations, garages, slaughter houses, laundries, industries, treatment plant of the hospital, kitchens, some overflowing septic tanks and indirectly through subsurface migration from many septic tanks at the vicinity of the canal. Inflows were modelled as point sources at 50m intervals. The model predictions was verified with the field measurements of N,P,DO and BOD concentrations along the canal reported elsewhere as at present during dry weather period. The model was then applied to assess the influence of two different restoration proposals on the water quality along the canal: Phase I - direct inflows and 30% of septic tanks are absent and Phase II - Phase I with another 60% of septic tanks are absent. Predictions show that the canal could be restored to an environmentally acceptable level by Phase I which requires only the community participation and only a little capital investment. Phase II will bring the canal to much better level though it require a considerable capital investment.
Artificial Muscles with a Polymer Gel Electrolyte Based on Polyacryonitrile (Pan)
(Unviersity of Peradeniya, Peradeniya, Sri Lanka, 1999-11-20) West, Keld; Skaarup, Steen; Bandaranayake, P. W. S. K.; Perera, Kumudu; Dissanayake, M. A. K. L.
Polymer gel electrolytes are formed by trapping a liquid electrolyte in a polymer matrix. They offer an approach to achieve high conductivity nearing that of the parent liquid electrolyte alongside good mechanical properties. Polymer networks found to be useful to form gel electrolytes include poly(acrylonitrile)(PAN), poly(methyl methacrylate) (PMMA), poly(vinyl chloride) (PVC) and poly(vinylidene fluoride) (PVDF). They have exhibited their potential capability in various applications. The most latest application of these gel electrolytes is in the artificial muscles which are defined as systems capable of converting chemical energy to mechanical energy. Different types of materials have been tested in artificial muscles. But, due to their practical difficulties such as requirement of high voltages and low displacements, the attention has diverted towards conducting polymers. Most studies have been done with conducting polymer based artificial muscles in liquid electrolytes. Recently, a keen interest has been put on dry artificial muscles where liquid electrolyte is replaced by a polymer electrolyte. Upon application of a potential, movements are registered as in a liquid electrolyte. This report is based on a gel eletrolyte comprising PAN, ethylene carbonate (EC), propylene carbonate (PC) and lithium trifluoromethane sulfonate (LiCF3S03) and its performance on artificial muscles prepared with conducting polymer polypyrrole (PPy). The composition having the maximum room temeprature condcivity and the optimum mechanical properties was determined by varying the salt concentration and the PAN amount respectively. It was found that the highest room temperature can be obtained at the salt concentration 0.87 molkg-1 and good mechanical properties are available with a PAN amount corresponding to 1/10 of the amount of the liquid electrolyte (by weight). The highest room temeprature conductivity was 1.21 x 10-3 S cm-1 and the electrolyte composition was 15mol%PAN : 42mol%EC : 36mol%PC : 7mol%LiCF3S03. To fabricate the artificial muscle, two identical polypyrrole electrodes polymerized in the presence of sodium dodecylbenzene sulfonate (SOBS) and having thicknesses of 10 µm were used. The gel electrolyte was sandwiched in between two PPy electrodes. Movements were observed in different potential windows. To accelerate the motion, gel electrolytes of different thicknesses were used. It could be noticed that thinner the gel electrolyte, faster the movements. But, using very thin electrolytes sometimes resulted short circuit effects. There are problems like evaporation of the solvents. Further studies are under way to overcome them.
Application of transfer maps on Factor Groups
(Unviersity of Peradeniya, Peradeniya, Sri Lanka, 1999-11-20) Seneviratne, P. S. B.
We wish to present the proofs of the following two results on transfer maps. (i) Let G be a finite group and let K be a normal subgroup of order n of G such that G/K is abelian. If G splits over K with H as a complement to K, 𝜏 is the transfer of G into H, ψ is the map from G to H such that ψ(hk) = h, for all h in H, and k in K, and v is the map defined by v(h) = hⁿ, then 𝜏 = ψV. (ii) Let G be a finite group. If G has an abelian Sylow p-subgroup then p does not divide |G'∩Z(G)|. Hence we show that if all Sylow p-subgroups of G are abelian then G'∩Z(G) = 1. Also, if G/Z(G) is a π group, then G' is also a π group. However, the converse of this result is not true. A counter example will be presented.
Crown dimensions of deciduous teeth of Sri Lankans
(Unviersity of Peradeniya, Peradeniya, Sri Lanka, 1999-11-20) Arambawatta, A. K. S.; Chandrasekara, M.; Nanayakkara, D.; Ekanayake, D. B.
Numerous studies on the metrical dimensions of the deciduous teeth have been carried out in several population groups. Although metrical dimensions of the permanent teeth of Sri Lankan are available, there is no information regarding the metrical dimensions of the deciduous teeth of Sri Lankans. The present study was carried out with the aim of establishing the metrical dimensions of the deciduous teeth in Sri Lankan Sinhalese children. A total of 610 teeth (324 male and 286 female) constituted the sample. Measurements of mesiodistal and buccolingual crown diameters were obtained from these teeth using a dental vernier caliper. The measurements were made to the nearest 0.1 millimeter by one investigator. The mean values for mesiodistal and buccolingual diameters were calculated. Students' t- test was carried out to find out the significance between the mean values of males and females. The differences between the mean values of mesiodistal and buccolingual crown dimensions for corresponding teeth of the right and left sides of the dental arches were not significant. The mean values of mesiodistal and buccolingual diameters of all teeth in males were greater than those in the females. The mesiodistal diameter of all maxillary and mandibular teeth in males showed significantly higher values (P<0.05). The buccolingual diameter of all teeth in males, except the mandibular first and second molar and the maxillary first molar showed significantly higher values (P

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