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  Subjects -> SCIENCES: COMPREHENSIVE WORKS (Total: 374 journals)
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Journal of the National Science Foundation of Sri Lanka
Journal Prestige (SJR): 0.157
Number of Followers: 0  

  This is an Open Access Journal Open Access journal
ISSN (Print) 1391-4588
Published by Sri Lanka Journals Online Homepage  [71 journals]
  • A novel approach for energy and exergy analysis of a fat plate solar
           collector with energy storage

    • Abstract: Experiments were conducted to evaluate the performance of a flat plate solar collector in terms of its energy, exergy, and efficiency. The data were analyzed using three factors in a Completely Randomized Design. The first factor was tilt angle with three levels, the second was air mass flow rates with four levels, and the third was heat storage fluid with four levels, making a 4 x 3 x 4 factorial experiment. The least significant difference between means was calculated with Alfa (α) < 0.01. The results showed that the maximum energy of 1509.74 kJ hr-1 was gained by the flat plate solar collector when a polyethylene glycol solution was used in head raised pipes at 11.76 kg min-1 air flow rates with a 30o collector tilt. The maximum exergy of 46.0 % was gained by the flat plate solar collector when air was used in head raised pipes at 4.67 kg min- 1 air flow rates, with 30o collector tilt angle, while the minimum exergy gain of 32.67 % was recorded for a polyethylene glycol solution in the solar collector at 1.78 kg min-1 air flow rates with collector tilting at 30o . The maximum efficiency of 39.71 % was gained by the flat plate solar collector when a polyethylene glycol solution was used in head raised pipes at 9.69 kg min-1 air flow rates with 40o collector tilt angle. The storage medium showed that the maximum energy of 40,207 kJ day-1 was stored in the energy storage unit per day, followed by 33,291 kJ day-1  stored in salt solution while the minimum energy of 29,640 kJ day-1 was stored with water.  Published on 2022-04-10 11:15:20
  • Sonication-assisted water extract of Dendronephthya gigantea exhibits
           anti-fine dust effects; attenuation of MAPK phosphorylation in macrophages

    • Abstract: Air pollution due to fine dust (FD) has become a global concern. Industrial effluents and traffic emissions combined with naturogenic sources influence this issue, which particularly impacts the East Asia region. Health concerns caused by this form of pollution include respiratory disorders. The development of anti-inflammatory agents requires an understanding of the underlying mechanism. This study investigated the impact of FD on RAW 264.7 macrophages and sonication-assisted water extract of soft coral Dendronephthya gigantea (DGE) as a potent anti-fine dust agent. Cytoprotective effects using MTT and NO production inhibition using the Griess assay were assessed. ELISA, western blotting, and RT-qPCR techniques were used to evaluate multiple molecular mediators involved in the inflammatory pathway. It was observed that iNOS, COX-2, and PGE2 , including pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6), were downregulated in a dose-dependent manner by DGE treatment. DGE inhibited the inflammatory responses initiated through FD by suppressing MAPK signaling in RAW 264.7 macrophages. This study provides insight into the protective mechanisms against FD, and suggests that D. gigantea could be a valuable, low-cost source of protein for potential use in the cosmeceutical and pharmaceutical sectors.  Published on 2022-04-10 10:27:52
  • Predominance of phylogenetic group B2 among commensal Escherichia coli in
           humans from Kandy District, Sri Lanka

    • Abstract: Escherichia coli is a commensal bacterial gut inhabitant in vertebrates, while some strains are pathogens. Analysis of the genetic substructure within E. coli has identified nine phylogenetic groups within the species, as group A, B1, B2, C, D, E, F, G and cryptic clade I. These groups vary in attributes such as host characteristics, pathogenicity, antibiotic sensitivity patterns and virulence profiles. The current study was conducted to determine the distribution of phylogenetic groups, commonly encountered sequence types (ST), and group B2 subgroups (SG) of human faecal E. coli in a sample population in the Kandy District, Sri Lanka. A total of 158 faecal swabs, collected from healthy individuals, were cultured on MacConkey agar and presumptive E. coli isolates were confirmed by a negative reaction on Simmons citrate agar. E. coli isolates were characterized according to their phylogenetic group, SG, and ST distribution by a series of PCR protocols. Results revealed a predominance of group B2 (28 %), followed by B1 (23 %), A (17 %), D (14 %), C (5 %), F (4 %), and E (3 %). Within phylogroup B2, SG III was predominant while ST 73, 95, and 131 were detected at low frequencies. ST 69 accounted for 20 % of the group D isolates. Distribution of phylogroups was independent of host gender except group D, which was significantly over-represented by males. As B2 E. coli are strongly associated with extraintestinal infections and a high degree of virulence, characterization of these human faecal E. coli isolates for antibiotic susceptibility and virulence profiles would be of clinical importance. Published on 2022-04-10 10:11:51
  • Optimization of high solids batch anaerobic co-digestion of
           lignocellulosic biomass and cow dung under mesophilic temperature

    • Abstract: Anaerobic digestion is applied to recover energy from rice straw (RS) which is a lignocellulosic agricultural residue produced in huge quantities in Asia and Africa. Because of the high solids content of this feedstock, high solids anaerobic co-digestion in batch mode must be further investigated. In this study, optimal operating conditions for the anaerobic co-digestion of RS with cow dung (CD) in batch mode, with and without leachate recirculation, were assessed under mesophilic temperature conditions. Preliminary experiments carried out in 2 L batch reactors confirmed that the concentration of RS in the mixture of substrates S0 , in g VSRS/kg of mixture is an important parameter. Only batch reactors with the lowest So values (29 g VSRS/kg) produced biogas and rest of the reactors followed a long lag phase. The use of digestate from a previous batch as an inoculum was investigated with So values of 29 and 55 g VSRS/kg. Use of the digestate with So of 29 g VSRS/kg improved both initial degradation kinetics and the methane yield measured after 60 days. However, at So of 55 g VSRS/kg, the degradation kinetics were affected and after two months, 32 % of the biodegradable organic matter could not be eliminated. When leachate recirculation was performed in 6 L leach-bed reactors (LBRs) with So between 30 and 65 g VS lowest SRS/kg, the highest methane yield was recorded at the lowest So value. It can be concluded that under batch mode, an RS concentration around 30 g VSRS/kg may be recommended for industrial applications.  Published on 2022-04-10 09:55:28
  • Characterization of landfill leachate at the Karadiyana open dumpsite, Sri
           Lanka, and assessment of water pollution in its vicinity

    • Abstract: Contamination of ground and surface waters by landfill leachate is a prime environmental concern. The present research assesses chemical composition of leachate generated in the Karadiyana open dumpsite in Sri Lanka and the groundwater pollution caused by the landfill. The leachate pollution index (LPI) of Karadiyana is 34.00, suggesting that it has the potential to contaminate the environment. The nitrate, ammonia, and total phosphate concentrations in leachate varied in the range of 20.70 to 167.80, 376.55 to 580.33 and 10.00 to 84.00 mg/L respectively. Four major groups, namely, tryptophan- and tyrosine-like protein fractions, and fulvic and humic fractions were identified in leachate using fluorescence data. The bio chemical oxygen demand (BOD) to chemical oxygen demand (COD) ratio of leachate in the present study varied between 0.39 and 0.49 which categorizes leachate into intermediate age with medium biodegradability. This observation was further verified by the average pH and COD values of leachate; 6.81 ± 0.08 and 2221 ± 45 mg/L, respectively. Only one out of ten dug wells located in a radius of about a kilometer from Karadiyana dumpsite can be classified as good water for drinking purposes though eight of ten are used for drinking at the moment. All ten dug wells exceeded the WHO recommended nitrate level.  Published on 2022-04-10 08:21:56
  • Novel nebulizer design with adaptive flow regulation

    • Abstract: Pharmaceutical therapy for certain respiratory diseases involves delivering aerosolized drugs directly to the respiratory tract through inhalation with nebulizers. This research is focused on designing an automated jet nebulizer that possesses the capability of dynamic flow regulation. The proposed nebulizer is composed of two modes, namely, the Compressed Air mode and the Oxygen Therapy mode. The automated triggering from one mode to another will be dependent upon the percentage of oxygen saturation of the patient, monitored from the SpO2 sensor. The compressed airflow will be delivered to the patient according to his or her volumetric breathing rate, derived with the aid of a temperature sensor-based algorithm. The compressor circuitry is incorporated with a PID control unit, which is a novel feature that acts as feedback as well as a safety mechanism in ensuring that the patient receives compressed air as per the flow rate decided by the system. At the end of the drug delivery, if the liquid level sensor detects the absence of medication within the nebulizer chamber, the nebulization process will be terminated. The results obtained from simulations showed that the PID unit functioned smoothly, with less overshoot and response time. Thus, the dynamic regulation of the motor speed with respect to the volumetric breathing rates was accomplished. A laminar flow was obtained from the outlet of the compressor towards the nebulizer tubing, and a turbulent flow was obtained within the chamber, as expected. No excessive turbulent flows or rotational flow patterns were detected.  Published on 2022-04-10 08:07:17
  • Vegetative and reproductive phenology of Cinnamomum verum J. Presl grown
           in intermediate climatic zone of Sri Lanka

    • Abstract: Efficient harvesting of cinnamon while maximizing the yield is highly dependent on its phenology. Many important studies on Ceylon cinnamon have been undertaken, though in-depth studies on vegetative and reproductive phenology of Cinnamomum verum are limited. Therefore, this study investigated the vegetative and reproductive phenology of C. verum, giving particular emphasis on the major phenological phases such as leaf flushing, flowering, and fruiting. The investigation was carried out from January 2018 to March 2019 to cover a complete annual phenological cycle at the Thihagoda site, in the intermediate climatic zone of Sri Lanka. The results indicate that the leaf emergence of C. verum in Sri Lanka takes place in flushes which appeared to be controlled by two factors, the seasonality and the rainfall after a dry period. The seasonal flushing took place in the four months period from February to May. The leaf longevity of C. verum in Sri Lanka is longer than 15 months. The leaf fall was not continuous and limited to a five-month period from March to July with a peak in March. The flowering in C. verum took place during October and November, however only 18.6 ± 5.6% of flower buds matured to flowers. Moreover, 94.1 ± 8.5% of flowers developed into young fruits. The timing of these phenological traits is important to manage the cinnamon productivity as it is recognized that the peeling ability of C. verum depends on the cambial activity which is controlled by source-sink relationships in assimilate partitioning in C. verum. Published on 2022-04-10 07:57:42
  • Determination of safe zone of the mandible for implant and bone harvesting
           (using CBCT) of mandible in a group of Sri Lankan subjects

    • Abstract: Bone grafting procedures are required for patients with insufficient bone volumes for dental implants. The incisive mandibular nerve is more prone to iatrogenic injury during bone graft harvesting. This study aimed at examining the relative position of the mandibular canal (MC), gender Variation and to observe a safe zone for the implant and bone harvesting. Cone beam computed tomography (CBCT) scans of 200 patients (males 56 %) with age ranging from 16 to 70 years (mean age, 34.1 ± 14.5 years) were selected from the database of the Dental Imaging Unit of the National Dental Teaching Hospital of Sri Lanka. The MC length, mental foramen (MF) diameter, location and the safe zone distance for bone graft harvesting were recorded for each hemi-mandible. The mean length of left and right MC of males were 6.99 ± 0.21 cm and 6.98 ± 0.22 cm, respectively while for females the mean length was equal for both sides (6.88 cm). The mean MF horizontal length of males was 0.32 ± 0.03 cm on the left and right sides while for females it was 0.31 ± 0.03 cm on either side. The vertical length of MF was 0.25 cm for both left and right (for both genders). The mean safe zone distance of the left and right mandibles for males were 0.27 ± 0.07 cm and 0.30 ± 0.06 cm, respectively while for females the values were 0.26 ± 0.06 cm and 0.27 ± 0.06 cm, respectively. The most frequent position of the MF among males was below the second premolar on each side of the mandible. The MF of females were frequently located below and between the first and second premolar on each side of the mandible. MC and other measurements showed a high sexual dimorphism. Therefore, gender variation in MC length, diameter and location of MF should be considered during surgical interventions such as implant and bone harvesting.  Published on 2022-04-10 05:39:29
  • Tropical cyclones in the Arabian Sea and the Bay of Bengal: comparison of
           environmental factors

    • Abstract: The Northern Indian Ocean is vulnerable to tropical cyclone (TC) related hazards that adversely affect people, infrastructure, and economies in the region. Considering the region’s importance, supportive environmental factors for TC (> 17 knots) activity in the Arabian Sea (AS) and the Bay of Bengal (BoB) have been examined utilizing ocean-atmosphere datasets (1891–2016). The reasons for more TCs during 2011 and 2015 and less during 2013 in the AS than the BoB have been discussed. A decreasing (increasing) trend in the TC frequency is observed in the BoB (AS), which correlates negatively (positively) with sea surface temperature (SST). Though the TC frequency is larger in the BoB, the AS has experienced higher TC frequency on five occasions (1902, 2001, 2004,2011 and 2015) during the 1891–2016 period. The observed trend in the Indian Ocean Dipole (IOD) index emphasizes a positive impact on the TC genesis in the AS. Results revealed that warmer SSTs supported by the co-occurrence of El Niño/Southern Oscillation (ENSO) and IOD events associated with a relatively deep 26 °C isothermal layer (D26) enhanced the TC formation in the AS during 2011 and 2015. The TC genesis is suppressed under the neutral conditions of ENSO and IOD (i.e., 2013) in the AS, and that brings the relative importance of the SST cooling associated with a deeper mixed-layer and shallow D26. Further, the observed differences in parameters between the regions are larger during the primary TC peak season (October - December). Although a recent increment of TCs is noted in the AS (compared to the BoB), the specific roles of the influencing factors on TC activities over the AS remain debatable. Published on 2022-04-10 05:21:15
  • Meta-QTL analysis identified stable quantitative trait loci (QTLs) and
           associated resistance gene analogues in rice

    • Abstract: Disease resistant rice varieties are mandatory for sustainable rice production to ensure the global food supply. This study aimed to identify meta-QTLs associated with the disease resistance and candidate R-genes. A consensus map was constructed by merging 9 QTL mapping studies, 115 QTLs and 943 markers. The consensus map was 1554.71 cM in length with a 1.65 cM-1 average marker density. Totally, 24 metaQTLs were projected on the consensus chromosome maps except on chromosomes 5, 6, and 10. Larger effect meta-QTLs (R2 ≥ 25 to 56 %) were reported on chromosomes 1, 2, 3, 4, 8, and 11. Three or more meta-QTLs were predicted on 1, 2, 7, 8, and 9 chromosomes. More than 62 % of the meta-QTLs were contributed by 3 or more mapping studies. Furthermore, 6 of the putative meta-QTLs collocated with 11 meta-QTLs from previous studies, and 23 resistance loci that are used in existing resistance breeding programs indicating robust expression. Nine meta-QTLs were associated with blast (BL) resistance whereas 14 were associated with both BL and sheath blight (SHB) resistance. Candidate gene mining identified 79 disease resistance gene analogues (RGAs) of which 74 % were complete putative R genes. Nine of the meta-QTLs predicted clusters of RGAs. Out of these, expression of LOC_Os11g12340 was cross validated using publicly available expression data in tissues infected with M. oryzae, indicating a functional role of this gene in the disease cycle. The outcome clearly exposed genomic abundance of R-genes and their potential functional redundancy. Further, these findings provide potential resources for rice breeding for disease resistance.  Published on 2022-04-10 04:59:20
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