http://dr.lib.sjp.ac.lk/handle/123456789/10585 2026-01-07T04:26:52Z http://dr.lib.sjp.ac.lk/handle/123456789/10596 Effect of Age and Gender on Voice Onset Time: Data from Sinhalese Narasimhan, S.V.; Karunarathne, W.G.S.S. Objective: To documenting the voice onset time in voiced and unvoiced stop consonants in Sinhala and to investigating the effects of age and gender on voice onset time values in Sinhalese speakers. Methods: Three groups of participants were employed. Group 1 included 20 children, Group 2 included 20 adults and Group 3 consisted of 20 elderly subjects. All the subjects spoke the dialect of central province of Sri Lanka. Words consisting of three Sinhala short vowels /a/, /i/ and /u/ in were recorded. Voice onset time values from two voiced and voiceless stop consonants were extracted. Results: Voiced stop consonants had significantly longer voice onset time values compared to voiceless stop consonants. Significant effect of age as well as gender on voice onset time values were also observed. Conclusion: Supplementary investigations on the normative aspects of voice onset time among the Sinhala population would provide additional insights and validated tools for indexing the articulatory and acoustic characteristics of stop consonants in Sinhalese. 2021-01-01T00:00:00Z http://dr.lib.sjp.ac.lk/handle/123456789/10595 Evaluation of salt content and effectiveness of excessive salt reduction methods in selected commercially available dried fish types in Sri Lanka Lakmini, D. P.; Munasinghe, H; Silva, A.B.G 2021-01-01T00:00:00Z http://dr.lib.sjp.ac.lk/handle/123456789/10594 Water barrier properties of carboxymethyl cellulose/halloysite nanotubes nanocomposite to be used in food packaging applications Wijesooriya, S.N.; Adassooriya, N. In this research, novel carboxymethyl cellulose (CMC) based nanocomposite film containing 5%wt of halloysite nanotubes (HNT) was fabricated via solvent casting method as a potential biodegradable packaging material. The performances of the nanocomposite packaging material was investigated by assessing the moisture content, moisture uptake, water solubility, water vapor barrier properties and opacity. The incorporation of 5%wt HNT into the film remarkably reduced the moisture uptake by ∼ 28.01% at 97% RH and 31.08% at 40% RH. Water permeability value of CMC/HNT film showed as 7.08 ± 0.26 × 10−11 gm/m2Pas at freezing, 3.37 ± 0.33 × 10−11 gm/m2Pas at refrigeration and 1.14 ± 0.00 × 10−11 gm/m2Pas at ambient environmental conditions respectively. Subsequent to the thermal annealing process, the water vapor permeation ability was drastically declined in the HNT added nanocomposite films at all three different conditions (freezing, refrigeration and ambient) due to enhancing the crystalline structure. Furthermore, the addition of nanofillers into the polymer matrix significantly induced the UV blocking property of the film. These findings disclosed that prepared CMC/5%HNT nanocomposite films can be a potential food packaging material. Keywords: barrier properties, carboxy methyl cellulose, halloysite nanotubes 2021-01-01T00:00:00Z http://dr.lib.sjp.ac.lk/handle/123456789/10593 Microwave-assisted one-pot multicomponent synthesis of indole derived fluorometric probe for detection of Co2+ ions Azees, R.; Cooray, A.T.; Kumarasinghe, K.G.U.R. Cobalt (Co2+) is an essential constituent in the human body while excessive exposure leads to severe systemic toxic reactions which highlight the importance of developing effective methods to detect Co2+ ions. A simple and highly efficient fluorescence enhanced turn OFF-ON chemosensor was synthesized to detect the paramagnetic Co2+. The ligand, N-((1H-indol-3-yl)(phenyl)methyl)aniline (L), was synthesized in 92% yield by means of hydrated ferric chloride catalyzed one -pot multicomponent microwave irradiation in the presence of Indole, benzaldehyde, and aniline as reactants. The major green principles of waste prevention, high atom economy (94.3%), green solvent, higher energy efficiency, and catalysis were the highlights of the ligand synthesis. The ligand exhibited remarkable fluorescence enhancement with Co2+ and a turn ON ratio of over 160-fold in MeOH/H2O (at pH 3.5) solution at an excitation wavelength of 369 nm in the Ultra-Violet range. The detection limit of L- Co2+ was 2.2 μM. The excitation and the emission spectra indicated stoke’s shift of 93 nm which supports the fluorescence enhancement observed in L- Co2+ with respect to the free ligand. The Job’s plot indicated fluorometric sensing of Co2+ ascribed to the complex formation with a stoichiometric ratio of 2:1 (L- Co2+). Furthermore, the high linearity (r2 =0.992) observed in the Benesi Hildebrand plot in a wide concentration range of 0.5−80 μM confirmed the above stoichiometric ratio. The association constant (Ka) for the L-Co2+ was determined to be 8.382 ×1 04 M−1 ± 5.8 ×103M−1.The prepared Co2+ fluorometric probe indicated long-term stability in −18 ℃ up to 45 days. Furthermore, the presence of Fe2+ and Fe3+ in the medium with Co2+ exhibited an interference effect in the fluorescence intensities. Upon further concentration studies, it was evident that the interference of Fe2+ and Fe3+ starts around 10.00 μM and rises exponentially. 2021-01-01T00:00:00Z