University of Peradeniya

About: University of Peradeniya is a education organization based out in Kandy, Sri Lanka. It is known for research contribution in the topics: Population & Poison control. The organization has 5970 authors who have published 7388 publications receiving 197002 citations.

Adsorption of Cd2+ and Pb2+ onto coconut shell biochar and biochar-mixed soil.

Abstract: Permeable reactive barrier (PRB) systems containing effective and low-cost adsorbents for heavy metals are expected to function as in situ treatment methods for leachate from waste landfills and contaminated groundwater surrounding the landfills in developing countries. This study was conducted to characterize the adsorption of Cd2+ and Pb2+ onto coconut shell biochar (fine granules), a local soil from Sri Lanka (Entisol), and a biochar-mixed soil (1:1 mixture of biochar and soil) as potential adsorbents for PRB systems. Batch experiments were carried out to investigate the effects of solution pH, contact time, initial ion concentration, and competitive ions on the Cd2+ and Pb2+ adsorption. Results showed that the adsorption kinetics of Cd2+ and Pb2+ onto all adsorbents were well described by the pseudo second order kinetics model and that adsorption isotherms followed the Langmuir model. In the range of pH ≥3, the initial solution pH had a minor effect on efficiency of metal removal and the removal of metals mostly exceeded 80 % for all adsorbents. Measured maximum adsorptions onto soil and biochar-mixed soil were 30.1 mmol/g for Cd2+ and 44.8–46.7 mmol/g for Pb2+. These adsorption capacities are similar to or higher than the values of biosorbents tested for wastewater treatment in previous studies, suggesting our tested materials would be useful as adsorbents of Cd2+ and Pb2+ in PRB systems. Additional analysis by scanning electron microscopy linked with energy dispersive X-ray revealed that both Cd2+ and Pb2+ exhibited high adsorption affinity towards soil particles while adsorbing randomly to biochar granules.

Concurrent outbreaks of Chikungunya and Dengue fever in Kandy, Sri Lanka, 2006–07: a comparative analysis of clinical and laboratory features

Abstract: Objectives: To compare the clinical and laboratory features of confirmed cases of Chikungunya and Dengue fever; to validate the clinical diagnosis based on serology. Methods: Cases with a clinical diagnosis of Chikungunya and Dengue fever were recruited for seroconfirmation during a concurrent epidemic in 2006–07, at the General Hospital, Peradeniya, Sri Lanka. Results: Of 54 patients with fever, serology confirmed 21 with Chikungunya infection, 20 with Dengue infection, and three co-infections, with sensitivity of the clinical diagnosis of 92% for Chikungunya fever and 95% for Dengue fever. The mean age of patients with Chikungunya fever was 45 years (range 21–74 years), and patients with Dengue fever was 30 years (range 15–63 years) (p = 0.005). Sixteen (70%) of Chikungunya fever patients were females, while 15 (71%) of those with Dengue fever were males (p = 0.007). Arthralgia was common to both groups (p = 0.155), while headache and a bleeding tendency were observed more in patients with Dengue fever. Twelve (57%) Chikungunya cases had acute arthritis compared with none in the Dengue group (p = 0.001), lasting mean 6 days (range 1–14 days). They developed chronic arthritic disability (range 1–6 months). Leucopenia was common to both Chikungunya and Dengue fever patients. However, thrombocytopenia was more pronounced in the Dengue patients (mean (SD) platelet count 75 (34)×10 9 /l) than in the Chikungunya patients (117 (70)×10 9 /l) (p = 0.001). In the Chikungunya group there was a positive correlation between duration of the illness and the platelet count (r = 0.181, p = 0.194), but the Dengue group showed a negative correlation (r = −0.309, p Conclusion: Most of the clinical and laboratory features of patients with Chikungunya and Dengue fever are similar. Arthritis is the pathgnomonic sign in patients with Chikungunya fever.

Oral submucous fibrosis: a contemporary narrative review with a proposed inter-professional approach for an early diagnosis and clinical management.

Abstract: Oral Submucous fibrosis (OSMF) has traditionally been described as “a chronic, insidious, scarring disease of the oral cavity, often with involvement of the pharynx and the upper esophagus”. Millions of individuals are affected, especially in South and South East Asian countries. The main risk factor is areca nut chewing. Due to its high morbidity and high malignant transformation rate, constant efforts have been made to develop effective management. Despite this, there have been no significant improvements in prognosis for decades. This expert opinion paper updates the literature and provides a critique of diagnostic and therapeutic pitfalls common in developing countries and of deficiencies in management. An inter-professional model is proposed to avoid these pitfalls and to reduce these deficiencies.

Numerical Modeling of GPR to Determine the Direct Ground Wave Sampling Depth

Abstract: The direct ground wave method of ground penetrating radar (GPR) has been suggested as a cost-effective means of estimating field-scale soil moisture variability for irrigation and water resource management. Knowing the sampling depth of the GPR direct ground wave (GW) is very important because it is critical to know the depth when measuring soil moisture in the field. Few studies have addressed this particular aspect of the GPR method. Numerical simulation of GPR electromagnetic waves using GPRMAX2D was performed for two-layer soil models to estimate the direct GW sampling depth for soil moisture. Dry over wet soil layers and wet over dry soil layers were modeled by using appropriate dielectric permittivity values for each layer. Model runs were conducted for a gradually decreasing upper layer thickness. The GW sampling depth was estimated as the upper dry or wet layer thickness when the modeled GW velocity decreased or increased by 5% as affected by the lower wet or dry layer, respectively. It was found from this modeling exercise that the GW sampling depth changed with the antenna frequency as well as the moisture content of the upper layer. A very strong linear relationship ( r 2 = 0.98) was found between the wavelength and the sampling depth of the GPR direct GW.