Pub Date : 2023-07-04DOI: 10.4038/jnsfsr.v51i2.11747
R. Seneviratne
Ethical conduct of research involving humans has gained relevance and importance over the years with the expansion of research beyond boundaries of traditional medical and clinical research into a multiplicity of disciplines with human participation. Human research is regarded as research conducted on or with or about people, or their tissues or cells or data obtained from them. Historically, it is stated that the Greek Philosopher Aristotle (384-322 BCE) was probably the first to discuss principles of ethics ‘by studying and offering criteria to assess human behaviour’. It is believed that he taught a course of ethics at the Lyceum during his mature years which was based on the many treatises he wrote on the subject. Increased attention to ethics in human research started after the Second World War following the judgment of the International Military Tribunal which also included 10 principles of permissible medical experiments which have since then been referred to as the Nuremburg Code (1949). Later discussions by the World Medical Assembly of the Code led to the adoption of the Helsinki Declaration (1964) which has been revised many times since then. The Council for International Organizations of Medical Sciences (CIOMS) which in association with the World Health Organizations (WHO) undertook its work on ethics in biomedical research in late 1970s. It has published an updated version with a wider scope of coverage titled ‘International Ethical Guidelines for Health-Related Research Involving Humans’ (2016). Close cooperation with World Medical Assembly has ensured that the guidelines are closely aligned to the Helsinki Declaration. Traditionally, ethics has received much attention both in clinical practice and in health research. Faculties of Medicine were the first to establish ethics review boards and ethics review committees in Sri Lanka to undertake review of research proposals with human participation for ethical aspects and issues and granting approval. The primary aim is to safeguard the interests and right of participants of research and prevent their exploitation. There is no doubt about the value of health research and the benefits it has brought and will continue to bring to ensure health, wellbeing, safety and quality of life of people. Most research on human participants is simple, observational, descriptive and non-invasive and the ethical issues though may be minimal, still needs explicit attention and review by an ethics review board before approval. The more complex research where human participants are subject to ‘experimentation’ or ‘interventions’ has many ethical issues that need to assessed by recognized ethics review committees with experience and capability to do so. If a new drug, a new vaccine, medicinal product, device, or equipment not already in use by people is to be tested on humans before being granted approval for use in day-to-day life by the appropriate authority, the researcher should adopt recommended p
{"title":"Ethics of research","authors":"R. Seneviratne","doi":"10.4038/jnsfsr.v51i2.11747","DOIUrl":"https://doi.org/10.4038/jnsfsr.v51i2.11747","url":null,"abstract":"\u0000Ethical conduct of research involving humans has gained relevance and importance over the years with the expansion of research beyond boundaries of traditional medical and clinical research into a multiplicity of disciplines with human participation. Human research is regarded as research conducted on or with or about people, or their tissues or cells or data obtained from them.\u0000Historically, it is stated that the Greek Philosopher Aristotle (384-322 BCE) was probably the first to discuss principles of ethics ‘by studying and offering criteria to assess human behaviour’. It is believed that he taught a course of ethics at the Lyceum during his mature years which was based on the many treatises he wrote on the subject. Increased attention to ethics in human research started after the Second World War following the judgment of the International Military Tribunal which also included 10 principles of permissible medical experiments which have since then been referred to as the Nuremburg Code (1949). Later discussions by the World Medical Assembly of the Code led to the adoption of the Helsinki Declaration (1964) which has been revised many times since then.\u0000The Council for International Organizations of Medical Sciences (CIOMS) which in association with the World Health Organizations (WHO) undertook its work on ethics in biomedical research in late 1970s. It has published an updated version with a wider scope of coverage titled ‘International Ethical Guidelines for Health-Related Research Involving Humans’ (2016). Close cooperation with World Medical Assembly has ensured that the guidelines are closely aligned to the Helsinki Declaration. \u0000 Traditionally, ethics has received much attention both in clinical practice and in health research. Faculties of Medicine were the first to establish ethics review boards and ethics review committees in Sri Lanka to undertake review of research proposals with human participation for ethical aspects and issues and granting approval. The primary aim is to safeguard the interests and right of participants of research and prevent their exploitation. There is no doubt about the value of health research and the benefits it has brought and will continue to bring to ensure health, wellbeing, safety and quality of life of people. Most research on human participants is simple, observational, descriptive and non-invasive and the ethical issues though may be minimal, still needs explicit attention and review by an ethics review board before approval. The more complex research where human participants are subject to ‘experimentation’ or ‘interventions’ has many ethical issues that need to assessed by recognized ethics review committees with experience and capability to do so. If a new drug, a new vaccine, medicinal product, device, or equipment not already in use by people is to be tested on humans before being granted approval for use in day-to-day life by the appropriate authority, the researcher should adopt recommended p","PeriodicalId":17429,"journal":{"name":"Journal of the National Science Foundation of Sri Lanka","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42005365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-30DOI: 10.4038/jnsfsr.v51i2.11080
V. Anusooya, S. Ponmalar, M. Manikandan, S. Gobalakrishnan
As a result of the development of advanced semiconductor-based optical switching devices and their commercialization, concepts and technologies in all-optical signal processing have evolved significantly in the past few years. In order to realize logical operations in photonic computing, universal gates are needed. In this research, the simple and compact all-optical NAND gate was designed using SOA and simulated at a high data rate of 10Gbps to 40 Gbps. The performance of the proposed NAND gate is shown by the numerical analysis for various input combinations and SOA. By changing wavelengths, injection currents, confinement factors, as well as optical components such as sources, amplifiers, and filters, a numerical analysis is performed. Unique results were obtained at a 10 Gbps data rate for NRZ-L user-defined bit sequences. This kind of all-optical NAND gate will be the perfect alternative in the field of optical computing to realize a high-speed optical communication network. An extinction ratio of 11.48 dB is achieved at a high-speed data rate of 10 Gbps to 40Gbps. The output spectrum of the designed NAND logic is also received for a wide input spectrum and the system responds selectively for the input wavelength at 1548.3 nm which is the probe signal wavelength.
{"title":"Simulation and Numerical Analysis of SOA Based All Optical NAND Gate for High Data Rate Communication","authors":"V. Anusooya, S. Ponmalar, M. Manikandan, S. Gobalakrishnan","doi":"10.4038/jnsfsr.v51i2.11080","DOIUrl":"https://doi.org/10.4038/jnsfsr.v51i2.11080","url":null,"abstract":"As a result of the development of advanced semiconductor-based optical switching devices and their commercialization, concepts and technologies in all-optical signal processing have evolved significantly in the past few years. In order to realize logical operations in photonic computing, universal gates are needed. In this research, the simple and compact all-optical NAND gate was designed using SOA and simulated at a high data rate of 10Gbps to 40 Gbps. The performance of the proposed NAND gate is shown by the numerical analysis for various input combinations and SOA. By changing wavelengths, injection currents, confinement factors, as well as optical components such as sources, amplifiers, and filters, a numerical analysis is performed. Unique results were obtained at a 10 Gbps data rate for NRZ-L user-defined bit sequences. This kind of all-optical NAND gate will be the perfect alternative in the field of optical computing to realize a high-speed optical communication network. An extinction ratio of 11.48 dB is achieved at a high-speed data rate of 10 Gbps to 40Gbps. The output spectrum of the designed NAND logic is also received for a wide input spectrum and the system responds selectively for the input wavelength at 1548.3 nm which is the probe signal wavelength.","PeriodicalId":17429,"journal":{"name":"Journal of the National Science Foundation of Sri Lanka","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47903157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-30DOI: 10.4038/jnsfsr.v51i2.11217
W.M.S. Kurera, N. Adikaram, D. Yakandawala, S.S.N. Maharachchikumbura, Jayasinghe, K. Samarakoon
Most of the commercial banana cultivars in Sri Lanka are susceptible to anthracnose disease. Colletotrichum musae has been known as the causal agent of banana anthracnose for decades and the pathogen has been identified using morphological characteristics. Molecular analyses based on multigene phylogenetics are now standard protocols to identify Colletotrichum species. The present study was aimed at identifying Colletotrichum species causing banana anthracnose by molecular and phenotypic characterization. Thirty-seven isolates were obtained from ripened bananas showing anthracnose symptoms, collected from different locations in the Central Province of Sri Lanka. Of them, 36 were preliminarily identified as Colletotrichum based on conidial morphology. The remaining isolate did not sporulate during the entire study period. Ten isolates taken for molecular studies consisted of eight with orange/white arial mycelia and orange conidial masses, one with a white to greyish colony and blackish clusters of ascomata, and one with a white to faint pink colour colony. DNA extracted from each isolate was subjected to multi-gene DNA sequence analysis using ITS, TUB, GAPDH and GS loci. Based on phylogenetic analyses, eight isolates were identified as Colletotrichum musae, and the other two as C. plurivorum and C. siamense. The vegetative morphology of C. plurivorum differed considerably from C. musae and C. siamense. Slight differences in colony morphology were observed among the C. musae isolates. Freshly harvested healthy bananas were artificially inoculated with isolates of C. musae or C. plurivorum and produced typical anthracnose lesions within a week. The Colletotrichum siamense isolate failed to develop anthracnose symptoms. This is the first report of C. plurivorum causing banana anthracnose.
{"title":"Molecular and phenotypic characterization of Colletotrichum plurivorum and Colletotrichum musae causing banana anthracnose disease in the Central Province of Sri Lanka","authors":"W.M.S. Kurera, N. Adikaram, D. Yakandawala, S.S.N. Maharachchikumbura, Jayasinghe, K. Samarakoon","doi":"10.4038/jnsfsr.v51i2.11217","DOIUrl":"https://doi.org/10.4038/jnsfsr.v51i2.11217","url":null,"abstract":"\u0000Most of the commercial banana cultivars in Sri Lanka are susceptible to anthracnose disease. Colletotrichum musae has been known as the causal agent of banana anthracnose for decades and the pathogen has been identified using morphological characteristics. Molecular analyses based on multigene phylogenetics are now standard protocols to identify Colletotrichum species. The present study was aimed at identifying Colletotrichum species causing banana anthracnose by molecular and phenotypic characterization. Thirty-seven isolates were obtained from ripened bananas showing anthracnose symptoms, collected from different locations in the Central Province of Sri Lanka. Of them, 36 were preliminarily identified as Colletotrichum based on conidial morphology. The remaining isolate did not sporulate during the entire study period. Ten isolates taken for molecular studies consisted of eight with orange/white arial mycelia and orange conidial masses, one with a white to greyish colony and blackish clusters of ascomata, and one with a white to faint pink colour colony. DNA extracted from each isolate was subjected to multi-gene DNA sequence analysis using ITS, TUB, GAPDH and GS loci. Based on phylogenetic analyses, eight isolates were identified as Colletotrichum musae, and the other two as C. plurivorum and C. siamense. The vegetative morphology of C. plurivorum differed considerably from C. musae and C. siamense. Slight differences in colony morphology were observed among the C. musae isolates. Freshly harvested healthy bananas were artificially inoculated with isolates of C. musae or C. plurivorum and produced typical anthracnose lesions within a week. The Colletotrichum siamense isolate failed to develop anthracnose symptoms. This is the first report of C. plurivorum causing banana anthracnose.","PeriodicalId":17429,"journal":{"name":"Journal of the National Science Foundation of Sri Lanka","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42663917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-30DOI: 10.4038/jnsfsr.v51i2.11101
W. Wijesundara, Dayani Gunathilaka, S. K. Madarasinghe, J. Andrieu, G. Muthusankar, N. R. Kankanamge, K. Kodikara
The southern coastal zone of Sri Lanka has been subjected to a variety of natural and anthropogenic influences over the past three decades. Understanding impacts of such influences on Land Use Land Cover (LULC) is vital for proper management of the coastal zone. This study, therefore, focused on mapping the change/s in the distribution of selected LULC in the selected sites, Bundala, Galle, Kalametiya, and Hambantota of the southern coastal zone, over last 24 years using satellite imagery. LULC maps of nine classes (mangrove, inland vegetation, marsh and grass, sand, bare land, built-up, cultivation, water, and unclassified) were created by employing an on-screen digitization technique achieving an accuracy of >70%. Trend analysis and two-sample proportion tests were used for statistical analyses, whereas geometric calculations were used for descriptive analyses. The results showed the highest overall change in LULC in Kalametiya, followed by Hambantota, Galle, and Bundala. The changes in the LULC classes are mainly attributed to the conversion of water to mangroves, marsh and grass areas in Kalametiya, water to built-up areas in Hambantota, cultivations to built-up areas in Galle, and marsh and grass areas to bare lands in Bundala. The causes of LULC changes were site specific. Trend analyses indicate the least LULC changes in Bundala possibly by 2025. The study highlights the significance of taking into account geographical dislocations when considering and anticipating the potential impacts of development projects over broader extents.
{"title":"Spatial and temporal changes of land use land cover distribution in selected sites of the southern coastal zone of Sri Lanka","authors":"W. Wijesundara, Dayani Gunathilaka, S. K. Madarasinghe, J. Andrieu, G. Muthusankar, N. R. Kankanamge, K. Kodikara","doi":"10.4038/jnsfsr.v51i2.11101","DOIUrl":"https://doi.org/10.4038/jnsfsr.v51i2.11101","url":null,"abstract":"\u0000The southern coastal zone of Sri Lanka has been subjected to a variety of natural and anthropogenic influences over the past three decades. Understanding impacts of such influences on Land Use Land Cover (LULC) is vital for proper management of the coastal zone. This study, therefore, focused on mapping the change/s in the distribution of selected LULC in the selected sites, Bundala, Galle, Kalametiya, and Hambantota of the southern coastal zone, over last 24 years using satellite imagery. LULC maps of nine classes (mangrove, inland vegetation, marsh and grass, sand, bare land, built-up, cultivation, water, and unclassified) were created by employing an on-screen digitization technique achieving an accuracy of >70%. Trend analysis and two-sample proportion tests were used for statistical analyses, whereas geometric calculations were used for descriptive analyses. The results showed the highest overall change in LULC in Kalametiya, followed by Hambantota, Galle, and Bundala. The changes in the LULC classes are mainly attributed to the conversion of water to mangroves, marsh and grass areas in Kalametiya, water to built-up areas in Hambantota, cultivations to built-up areas in Galle, and marsh and grass areas to bare lands in Bundala. The causes of LULC changes were site specific. Trend analyses indicate the least LULC changes in Bundala possibly by 2025. The study highlights the significance of taking into account geographical dislocations when considering and anticipating the potential impacts of development projects over broader extents.\u0000 ","PeriodicalId":17429,"journal":{"name":"Journal of the National Science Foundation of Sri Lanka","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45886262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-30DOI: 10.4038/jnsfsr.v51i2.11123
T.M. Munasinghe, U. Premarathne, D. Weerasinghe
The Mannar Basin extends over 45,000 km2 off the western coast of Sri Lanka. It has evolved due to the multiphase rifting between Indo-Lanka landmasses during the Barremian-Paleocene time. The sediment thickness of the basin ranges from about 4 to 10 km. The northern part of the basin is a targeted area for hydrocarbon exploration in Sri Lanka. Though two natural gas discoveries were made in 2011, the basin remains a frontier due to lack of well penetration and 3D seismic coverage. As a result, the depositional features of sediment in the basin are little known. This study focuses on identifying paleo depositional features in the Albian and Aptian strata using 650 km2 3D seismic data from the Mannar Basin. Root Mean Square (RMS) amplitude was used to characterize the depositional features in three-time windows on IHS Kingdom software (v.8.3). The results show the existence of a multi-level paleo submarine fan system in the Albian and Aptian strata. They are located relatively close to the western coastline compared to the fan system in the Eocene strata. The deposition of this paleo submarine fan system has taken place in a shelf marine environment and has been influenced by relatively high sea levels during the Albian and Aptian compared to the relatively low sea levels in the Paleocene and Eocene.
{"title":"Identification of depositional features in the Albian and Aptian sections over the hydrocarbon exploration block M2 on the Mannar Basin, Sri Lanka","authors":"T.M. Munasinghe, U. Premarathne, D. Weerasinghe","doi":"10.4038/jnsfsr.v51i2.11123","DOIUrl":"https://doi.org/10.4038/jnsfsr.v51i2.11123","url":null,"abstract":"The Mannar Basin extends over 45,000 km2 off the western coast of Sri Lanka. It has evolved due to the multiphase rifting between Indo-Lanka landmasses during the Barremian-Paleocene time. The sediment thickness of the basin ranges from about 4 to 10 km. The northern part of the basin is a targeted area for hydrocarbon exploration in Sri Lanka. Though two natural gas discoveries were made in 2011, the basin remains a frontier due to lack of well penetration and 3D seismic coverage. As a result, the depositional features of sediment in the basin are little known. This study focuses on identifying paleo depositional features in the Albian and Aptian strata using 650 km2 3D seismic data from the Mannar Basin. Root Mean Square (RMS) amplitude was used to characterize the depositional features in three-time windows on IHS Kingdom software (v.8.3). The results show the existence of a multi-level paleo submarine fan system in the Albian and Aptian strata. They are located relatively close to the western coastline compared to the fan system in the Eocene strata. The deposition of this paleo submarine fan system has taken place in a shelf marine environment and has been influenced by relatively high sea levels during the Albian and Aptian compared to the relatively low sea levels in the Paleocene and Eocene.","PeriodicalId":17429,"journal":{"name":"Journal of the National Science Foundation of Sri Lanka","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48633286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-30DOI: 10.4038/jnsfsr.v51i2.10713
H. Prasanna, M. D. K. L. Gunathilaka, H. Iz
Accurate long-term measurements of sea level are fundamental to evaluating coastal risks, such as the impact of sea-level rise on near-shore ecosystems, groundwater dynamics, and coastal flooding. This study examines sea-level variability at Colombo, Sri Lanka using satellite altimetry, tide gauge measurements separately and their conflated solution under a single model. Modelling of conflated satellite altimetry and tide gauge measurements shows a geocentric (absolute) local sea-level rise of 3.56 ± 0.32 mm/y without any signature of a uniform acceleration since 1981 at this locality. The measurements disclosed statistically significant periodic changes in sea level of luni-solar origin. The conflated model solution enabled the estimation of a statistically significant in-situ vertical land motion (0.58 ± 0.19 mm/yr) without the aid of global positioning measurements. The conflation model explains 98% of the sea-level variability, which makes it suitable for accurate seal level predictions for coastal risk assessments in Colombo, Sri Lanka.
{"title":"Sea level variability at Colombo, Sri Lanka, inferred from the conflation of satellite altimetry and tide gauge measurements","authors":"H. Prasanna, M. D. K. L. Gunathilaka, H. Iz","doi":"10.4038/jnsfsr.v51i2.10713","DOIUrl":"https://doi.org/10.4038/jnsfsr.v51i2.10713","url":null,"abstract":"Accurate long-term measurements of sea level are fundamental to evaluating coastal risks, such as the impact of sea-level rise on near-shore ecosystems, groundwater dynamics, and coastal flooding. This study examines sea-level variability at Colombo, Sri Lanka using satellite altimetry, tide gauge measurements separately and their conflated solution under a single model. Modelling of conflated satellite altimetry and tide gauge measurements shows a geocentric (absolute) local sea-level rise of 3.56 ± 0.32 mm/y without any signature of a uniform acceleration since 1981 at this locality. The measurements disclosed statistically significant periodic changes in sea level of luni-solar origin. The conflated model solution enabled the estimation of a statistically significant in-situ vertical land motion (0.58 ± 0.19 mm/yr) without the aid of global positioning measurements. The conflation model explains 98% of the sea-level variability, which makes it suitable for accurate seal level predictions for coastal risk assessments in Colombo, Sri Lanka.","PeriodicalId":17429,"journal":{"name":"Journal of the National Science Foundation of Sri Lanka","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45349445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-30DOI: 10.4038/jnsfsr.v51i2.10868
A. Fernando, S. Liyanage, A. Cooray
Fluoride is beneficial for human health only in a narrow concentration range. Over the years, many analytical techniques have been developed to quantify fluoride in a variety of sample matrices. In this research, fluoride concentrations of twenty (20) natural water samples determined by SPADNS (SPA) and Eriochrome Cyanine R (ECR) colorimetric methods were evaluated to ascertain whether these methods can produce comparable fluoride concentrations. According to the paired t test for comparing individual differences, the two datasets are different at 95% confidence level suggesting that the two analytical methods produce statistically different fluoride concentrations for the analysed water samples. The potential interferences of Al3+, Ca2+, and Mg2+ on the fluoride analysis was evaluated using 0.85 mg L-1 fluoride standard solutions spiked with various amount of the above-mentioned metal ions. The highest interference was observed with Al3+ ions, which underestimated the fluoride concentration by 26% and 23% for ECR and SPA methods respectively at 20.0 mg L-1 Al3+ concentrations. The minimum interference was observed for Ca2+ ions which underestimated the fluoride concentration by 8% and 7% for ECR and SPA methods respectively at 100.0 mg L-1 Ca2+ concentrations. Acid distillation resulted in the samples spiked with Ca2+ and Mg2+ ions in the range of 0.50 to 100.0 mg L-1 reaching the theoretical concentration of 0.85 mg L-1. Acid distillation also worked well for the Al3+- fortified samples, except for Al3+ concentration at 20 mgL-1. The efficiency of the acid distillation method was also tested with three (03) natural water samples. The fluoride concentration increased significantly after the acid distillation; however, even after the acid distillation, statistically comparable fluoride concentrations were not observed.
{"title":"Fluoride analysis in aqueous solutions - a comparison of two colorimetric methods","authors":"A. Fernando, S. Liyanage, A. Cooray","doi":"10.4038/jnsfsr.v51i2.10868","DOIUrl":"https://doi.org/10.4038/jnsfsr.v51i2.10868","url":null,"abstract":"\u0000Fluoride is beneficial for human health only in a narrow concentration range. Over the years, many analytical techniques have been developed to quantify fluoride in a variety of sample matrices. In this research, fluoride concentrations of twenty (20) natural water samples determined by SPADNS (SPA) and Eriochrome Cyanine R (ECR) colorimetric methods were evaluated to ascertain whether these methods can produce comparable fluoride concentrations. According to the paired t test for comparing individual differences, the two datasets are different at 95% confidence level suggesting that the two analytical methods produce statistically different fluoride concentrations for the analysed water samples. The potential interferences of Al3+, Ca2+, and Mg2+ on the fluoride analysis was evaluated using 0.85 mg L-1 fluoride standard solutions spiked with various amount of the above-mentioned metal ions. The highest interference was observed with Al3+ ions, which underestimated the fluoride concentration by 26% and 23% for ECR and SPA methods respectively at 20.0 mg L-1 Al3+ concentrations. The minimum interference was observed for Ca2+ ions which underestimated the fluoride concentration by 8% and 7% for ECR and SPA methods respectively at 100.0 mg L-1 Ca2+ concentrations. Acid distillation resulted in the samples spiked with Ca2+ and Mg2+ ions in the range of 0.50 to 100.0 mg L-1 reaching the theoretical concentration of 0.85 mg L-1. Acid distillation also worked well for the Al3+- fortified samples, except for Al3+ concentration at 20 mgL-1. The efficiency of the acid distillation method was also tested with three (03) natural water samples. The fluoride concentration increased significantly after the acid distillation; however, even after the acid distillation, statistically comparable fluoride concentrations were not observed.","PeriodicalId":17429,"journal":{"name":"Journal of the National Science Foundation of Sri Lanka","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49351680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-30DOI: 10.4038/jnsfsr.v51i2.11127
M. Jayasinghe, M. Gunasekara, M. Perera, K. Karunarathna, G. U. Chandrasiri, I. Hewajulige
King coconut (Cocos nucifera var. aurantiaca) is a tropical nut with notable nutritional and medicinal values. King coconut water (KCW) and king coconut kernel (KCK) are sweet and refreshing. They undergo several changes during maturation. The objective of this study was to assess the physico-chemical changes of KCW and KCK with maturity. Three different maturity stages (6, 7, and 8 months) of the variety aurantica, known locally as ‘Nawasi Thembili’ were studied for several physico-chemical parameters. Whole nut weight (g), nut-circumference (cm), colour (water/kernel) (*L), nut-water volume (mL), kernel weight (g), and kernel thickness (mm) were assessed as physical parameters, while pH, total soluble solids (oBrix), titratable acidity (as % ascorbic acid), total sugars (g/100g; g/100mL), and minerals (mg/L; mg/kg) were analysed as chemical attributes. Sugars were estimated using Agilent 1260 HPLC and ICP-MS was used to measure the mineral profile. Results revealed that all the tested physical parameters of KCW and KCK increased significantly (p < 0.05) with maturity. The pH, TSS, total sugars, and acidity of KCW increased significantly (p < 0.05), while mineral content decreased significantly (p < 0.05) with maturity. However, the TSS and minerals of KCK decreased significantly (p < 0.05) with maturity and a higher sucrose content was reported in KCK compared to KCW at later maturity. The Ca+2 and Mg+2 were prominent in both KCW and KCK. The study concluded that the physico-chemical characteristics varied widely with the maturity of king coconuts. The selection of optimum harvest maturity to match the preferred attributes of intended applications is suggested.
{"title":"Study on compositional changes of king coconut (Cocos nucifera var. aurantiaca) water and kernel during maturation and evaluation of optimum quality characteristics targeting commercial applications","authors":"M. Jayasinghe, M. Gunasekara, M. Perera, K. Karunarathna, G. U. Chandrasiri, I. Hewajulige","doi":"10.4038/jnsfsr.v51i2.11127","DOIUrl":"https://doi.org/10.4038/jnsfsr.v51i2.11127","url":null,"abstract":"\u0000King coconut (Cocos nucifera var. aurantiaca) is a tropical nut with notable nutritional and medicinal values. King coconut water (KCW) and king coconut kernel (KCK) are sweet and refreshing. They undergo several changes during maturation. The objective of this study was to assess the physico-chemical changes of KCW and KCK with maturity. Three different maturity stages (6, 7, and 8 months) of the variety aurantica, known locally as ‘Nawasi Thembili’ were studied for several physico-chemical parameters. Whole nut weight (g), nut-circumference (cm), colour (water/kernel) (*L), nut-water volume (mL), kernel weight (g), and kernel thickness (mm) were assessed as physical parameters, while pH, total soluble solids (oBrix), titratable acidity (as % ascorbic acid), total sugars (g/100g; g/100mL), and minerals (mg/L; mg/kg) were analysed as chemical attributes. Sugars were estimated using Agilent 1260 HPLC and ICP-MS was used to measure the mineral profile. Results revealed that all the tested physical parameters of KCW and KCK increased significantly (p < 0.05) with maturity. The pH, TSS, total sugars, and acidity of KCW increased significantly (p < 0.05), while mineral content decreased significantly (p < 0.05) with maturity. However, the TSS and minerals of KCK decreased significantly (p < 0.05) with maturity and a higher sucrose content was reported in KCK compared to KCW at later maturity. The Ca+2 and Mg+2 were prominent in both KCW and KCK. The study concluded that the physico-chemical characteristics varied widely with the maturity of king coconuts. The selection of optimum harvest maturity to match the preferred attributes of intended applications is suggested.","PeriodicalId":17429,"journal":{"name":"Journal of the National Science Foundation of Sri Lanka","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42170733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-30DOI: 10.4038/jnsfsr.v51i2.10777
L. Somathilake
By discretising in space, a non-linear time fractional reaction-diffusion equations (TFRDEs) can be converted into a system of time-fractional differential equations (TFDEs). The full memory method (FMM) and short memory method (SMM) are well-established memory selection methods used in the time integration of TFDEs. The main drawbacks of FMM and SMM are higher computational cost and uncontrollable error respectively. The only way to increase the accuracy of SMM is by increasing short memory length which causes an increase in computational cost. Especially when we apply these two methods to integrate TFRDEs, we have to solve a large system of TFDEs. Therefore, the drawbacks of these two methods affect seriously, when these are applied to solve TFRDEs. This paper aims to investigate the accuracy and efficiency of the memory selection method, Exponentially Decreasing Random Memory Method (EDRMM), and compare it with FMM and SMM when these methods apply to integrate TFRDEs. Based on these three memory selection methods, three semi-implicit numerical schemes namely semiimplicit scheme with full memory method (SI-FMM), semi-implicit scheme with short memory method (SI-SMM), and semi-implicit scheme with exponentially decreasing random memory method (SI-EDRMM)) are proposed and the accuracy and CPU time (computational time (CT)) of these three numerical schemes are compared. To do this comparison, these three numerical schemes are applied to four TFRDEs whose exact solutions are known. Numerical experiments confirm that the accuracy and efficiency of the SI-EDRMM are better than that of SI-SMM and the efficiency of SI-EDRMM is higher than that of SI-FMM. Therefore, EDRMM is better than SMM and FMM for the integration of TFRDEs.
{"title":"Comparative analysis of three memory selection methods for time integration of Fractional Reaction-Diffusion Equations","authors":"L. Somathilake","doi":"10.4038/jnsfsr.v51i2.10777","DOIUrl":"https://doi.org/10.4038/jnsfsr.v51i2.10777","url":null,"abstract":"By discretising in space, a non-linear time fractional reaction-diffusion equations (TFRDEs) can be converted into a system of time-fractional differential equations (TFDEs). The full memory method (FMM) and short memory method (SMM) are well-established memory selection methods used in the time integration of TFDEs. The main drawbacks of FMM and SMM are higher computational cost and uncontrollable error respectively. The only way to increase the accuracy of SMM is by increasing short memory length which causes an increase in computational cost. Especially when we apply these two methods to integrate TFRDEs, we have to solve a large system of TFDEs. Therefore, the drawbacks of these two methods affect seriously, when these are applied to solve TFRDEs. This paper aims to investigate the accuracy and efficiency of the memory selection method, Exponentially Decreasing Random Memory Method (EDRMM), and compare it with FMM and SMM when these methods apply to integrate TFRDEs. Based on these three memory selection methods, three semi-implicit numerical schemes namely semiimplicit scheme with full memory method (SI-FMM), semi-implicit scheme with short memory method (SI-SMM), and semi-implicit scheme with exponentially decreasing random memory method (SI-EDRMM)) are proposed and the accuracy and CPU time (computational time (CT)) of these three numerical schemes are compared. To do this comparison, these three numerical schemes are applied to four TFRDEs whose exact solutions are known. Numerical experiments confirm that the accuracy and efficiency of the SI-EDRMM are better than that of SI-SMM and the efficiency of SI-EDRMM is higher than that of SI-FMM. Therefore, EDRMM is better than SMM and FMM for the integration of TFRDEs.","PeriodicalId":17429,"journal":{"name":"Journal of the National Science Foundation of Sri Lanka","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46301677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-30DOI: 10.4038/jnsfsr.v51i2.11396
U. Samarajeewa
Polycyclic aromatic hydrocarbons (PAHs) are of petrogenic or pyrogenic origin. Of the known few hundred PAHs, 16 are identified to be toxic, of which 8 are teratogenic. Of the 8, 4 are carcinogens. Among them, Benzo[a]pyrene (BaP) possesses the highest carcinogenicity and is used as a marker in toxicity studies. PAHs of petrogenic origin contaminate soil, water and air. They may occur in air associated with dust particles. PAHs of pyrogenic origin are generated during burning of wood and other organic matter. They are also produced from lipids and carbohydrates during heating of foods. PAHs are mostly identified with grilling, smoking, frying, roasting and toasting of foods. Among the foods, formation of PAHs is studied mostly in association with grilling of fish and meat, where contacts occur between the dripping lipids and naked flames. The generated PAHs get deposited back on fish and meat muscles. PAHs in smoke are deposited on food surfaces on exposure to contaminated air from the vehicle fumes and smoke curing of foods. PAHs are formed during mechanical expulsion of edible oils. Presence of markers, carcinogenic PAHs and total PAHs in different foods and their extent of formation and deposition is discussed in relation to food safety hazards and health implications. Among the local foods and food preparation habits, the role of coconut oil, smoke curing of foods and formation of PAHs even under mild conditions of heat such as manufacture of black tea are reviewed. Recommendations for future actions, research and implementing food regulations to minimize PAHs in foods are presented.
{"title":"Polycyclic aromatic hydrocarbons and food safety: A review","authors":"U. Samarajeewa","doi":"10.4038/jnsfsr.v51i2.11396","DOIUrl":"https://doi.org/10.4038/jnsfsr.v51i2.11396","url":null,"abstract":"\u0000Polycyclic aromatic hydrocarbons (PAHs) are of petrogenic or pyrogenic origin. Of the known few hundred PAHs, 16 are identified to be toxic, of which 8 are teratogenic. Of the 8, 4 are carcinogens. Among them, Benzo[a]pyrene (BaP) possesses the highest carcinogenicity and is used as a marker in toxicity studies. PAHs of petrogenic origin contaminate soil, water and air. They may occur in air associated with dust particles. PAHs of pyrogenic origin are generated during burning of wood and other organic matter. They are also produced from lipids and carbohydrates during heating of foods. PAHs are mostly identified with grilling, smoking, frying, roasting and toasting of foods. Among the foods, formation of PAHs is studied mostly in association with grilling of fish and meat, where contacts occur between the dripping lipids and naked flames. The generated PAHs get deposited back on fish and meat muscles. PAHs in smoke are deposited on food surfaces on exposure to contaminated air from the vehicle fumes and smoke curing of foods. PAHs are formed during mechanical expulsion of edible oils. Presence of markers, carcinogenic PAHs and total PAHs in different foods and their extent of formation and deposition is discussed in relation to food safety hazards and health implications. Among the local foods and food preparation habits, the role of coconut oil, smoke curing of foods and formation of PAHs even under mild conditions of heat such as manufacture of black tea are reviewed. Recommendations for future actions, research and implementing food regulations to minimize PAHs in foods are presented. ","PeriodicalId":17429,"journal":{"name":"Journal of the National Science Foundation of Sri Lanka","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45958754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"综合性期刊","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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