Browsing by Author "Nilmini, A.H.L.R."
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Item Nitrosoamine free preservative system for natural rubber latex(Uva Wellassa University of Sri Lanka, 2013) Udayangani, G.G.D.; Nilmini, A.H.L.R.; Sirimanne, P.M.colloidal dispersion of rubber particles in an aqueous medium, containing usually from about 20% to about 40% w/w rubber particles (dry rubber) and about 5% w/w non-rubber compounds, including carbohydrates, proteins, phospholipids and metal salts. Since it provides an optimum environment for microbial growth, in the absence of a proper preservation, the carbohydrates which the latex contains are oxidized in to short chain volatile fatty acids due to microbial activities. These acids destabilize the latex which results the coagulation of rubber particles (Blackley, 1997). Preservatives can effectively inhibit the bacterial growth in fresh NR latex. Hence the formation of acidic compounds resulting from bacterial activity in the latex is inhibited, which in turn inhibits coagulation. Since the most widely used preservative, Tetramethyl thiurumdisulfide (TMTD) forms carcinogenic nitrosamine, present invention is mainly focused on the provision of a nitrosoamine free preservative system for latex concentrate to stabilize the latex over a period of six months. Volatile fatty acid number is an important measure of the level of deterioration and stability of the latex. Therefore the preservative activities of new developing system (NDS) for treated latex concentrate was tested based on the measurements of volatile fatty acids (VFA) number test. The current study was carried out at the Rubber chemistry & Technology laboratories of Rubber Research Institute, Ratmalana. Three experimental trials with different treatments of NDS were conducted during this study. The trial (I) was carried out to find out the optimum concentration of NDS in preservation of natural rubber latex. In order to compare the efficiency of NDS with the conventional preservative, the VFA number of the latex, treated with ammonia/TMTD/ZnO (TZ) system and NDS was determined respectively. In trial (II), the effect of NDS on latex preservation in combination with a co-activator was determined. The effect of ammonia on the activity of novel preservative and the appropriate combination of ammonia and NDS to preserve and stabilize the latex were evaluated in trial (III).The appropriate combination was used to prepare centrifuged latex and other properties of the concentrated latex such as total solids content (TSC), dry rubber content (DRC), pH, KOH number, Brookfield viscosity were measured according to ISO standard methods and compared with the centrifuged latex preserved by adding 0.2% ammonia (NH 3), 0.025% of 1:1 mixture of tetramethylthiuramdisulphide (TMTD) and Zinc oxide (ZnO) combination as a control sample.VFA values of trial (I) and (II) were analyzed using one way analysis of variance (ANOVA) with MINITAB statistical package 16.0 version. The Experiment trials were done using complete randomized design (CRD). Means comparison of results was done by using the least significant difference (P<0.05) test (LSD).Item Phytochemical Screening, Quantitative Analysis and In Vitro Cytotoxic Potential of Justicia adhathoda Leaf Extracts(Uva Wellassa University of Sri Lanka, 2021) Silva, A.B.W.R.; Nugara, N.N.R.N.; Manage, P.M.; Undugoda, L.J.S.; Udayanga, D.; Nilmini, A.H.L.R.Justicia adhathoda L., also known as “Adhathoda” is one of the widely used medicinal plants in indigenous medicinal systems in Sri Lanka and India. Previous studies have found several beneficial effects of different solvent extracts of this plant. However, the best solvent to extract much of the phytoconstituents has not been studied. Therefore, the present study was focused on identification, quantification of phytoconstituents in different crude extracts and in vitro cytotoxic effect of J. adhathoda. Plant leaves were collected from Ambilipitiya, Sri Lanka. Ethanol (EE), hexane (HE) and water (WE) extracts were prepared by adding 1 g of powdered leaf samples to 25 mL of ethanol (99.9%), n-hexane and distilled water, separately in triplicates. Preliminary phytochemical screening was performed according to the Harborne method. Total phenolic content (TPC) was measured spectrophotometrically by Folin-Ciocalteu assay and total flavonoid content (TFC) was determined using aluminum chloride colorimetric assay. To identify the toxicity level of J. adhathoda, different concentration of the WE were exposed to 3T3-L1 cells, a well-established cell culture model that is extensively used to study adipogenesis. The treatment was carried out for 8 days and performed MTS assay to determine the suitability of the WE consumption. Phytochemical screening results showed the availability of flavonoids, terpenoids, steroids, anthocyanins, alkaloids and coumarins in the WE. In contrast, tannin and alkaloids were abundant in the EE. TPC in the WE was 8-fold higher than the EE. The TFC in the EE was 20-fold higher than HE, and marked the highest. Collectively, the best solvent to extract the maximum amount of phytoconstituents was found as distilled water. The WE showed no toxicity below 500 μg/mL against 3T3-L1 adipocytes. The presence of high content of different phytoconstituents in WE of J. adhathoda is a great advantage to gain the health benefits as herbal tea or herbal porridges. These results provide referential information to identify the medicinal value of J. adhathoda and to be utilized in screening novel target compounds to treat various diseases. Keywords: Justicia adhathoda; phytochemical analysis; Medicinal plant; TFC; TPC; 3T3-L1Item Uniaxial Tensile Properties of Polyester Textile Waste Fiber Reinforced Thermoplastic Waste Composite(Uva Wellassa University of Sri Lanka, 2021) Sulochani, R.M.N.; Jayasinghe, R.A.; Nilmini, A.H.L.R.; Priyadarshana, G.The textile industry plays a significant role in the Sri Lankan economy. However, the management of textile waste has become a critical challenge faced by the industry. Most of the generated textile waste typically goes to open dumpsites, disposed of through open burning or incinerated. However, due to the large volumes of waste generation, the textile sector has paid clear attention to seeking better solutions to manage their waste. As such, there has been an increased interest to develop novel materials from industrial waste. Hence, the aim of this work is to develop and characterize composite materials using post-industrial polyester textile waste as fiber reinforcement and waste packaging materials as the polymer matrix as a new solution to the generated waste. The materials have been selected as polyester textile waste as the fiber reinforcement and thermoplastic waste packaging material as the matrix. Both materials were collected from the Sri Lankan textile industries. The composites containing 0%wt, 2.5%wt, 5%wt, 7.5%wt, 10%wt, 15%wt, and 20%wt reinforcement were manufactured using the compression moulding technique. No additional binders were added. The uniaxial tensile test was conducted according to the ASTM D 638 standard, and the Ultimate Tensile Strength and Young’s Modulus were focused for the study. According to the obtained results, the Ultimate Tensile Strength and the Young’s Modulus have increased up to a certain percentage of fiber reinforcement weight in the composite. Moreover, both uniaxial tensile strength and young’s modulus have reduced with increasing reinforcement fiber loading when passing that particular percentage. Accordingly, among the seven types of composite materials developed with different fiber reinforcement weight percentages, 7.5% wt. waste polyester textile fiber-reinforced composite shows the best performance for the uniaxial tensile properties. Experimental findings show that the uniaxial tensile properties of the developed composite show a positive trend to use as a substitute for non-structural applications such as particleboards. Keywords: Polyester textile fiber; Textile waste; Thermoplastic; Tensile properties