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The Effect of Hydrothermal Duration on the Formation of Activated Edgesites of 2-H Molybdenum Disulfide and the of Hydrogen Evolution Performances of the Material

Sun, 01 Jan 2023 00:00:00 GMT

Title: The Effect of Hydrothermal Duration on the Formation of Activated Edgesites of 2-H Molybdenum Disulfide and the of Hydrogen Evolution Performances of the Material Authors: Premadasa, P.M.; Panamaldeniya, S. A.; Munasinghe, H.; Gunawardhana, N. Abstract: Molybdenum disulfide (MoS2) is a nontoxic, environmentally friendly, abundant semiconducting material which is widely used in the areas of hydrogen storage, gas sensing and, solid super lubricant. It has three major phases called 1-T MoS2, 2-H MoS2 and 3-R MoS2. Among them 2-H MoS2 form is the stable form which has a hexagonal phase structure with an activated edge. Therefore, Activation of the material is possibly changing by making differences on nature of material edges. In this work, we report that influence of duration of hydrothermal process toward the growth of edge sites of 2-H molybdenum disulfide nanocomposites. In this study, we have synthesized three 2-H MoS2 nanostructures by facile hydrothermal route by using Ammonium molybdate, Thioacetamide, and urea as the basic precursors. All the samples were prepared at 200 ℃ temperature by changing the duration of hydrothermal process as 24h, 36h and, 48h. The samples were characterized by powder X-ray diffraction (PXRD) and Scanning electron microscope (SEM) for the phase confirmation and morphological characterizations respectively. Next, Electrochemical characterizations were carried out by using linear sweep voltammetry under the basic medium. Powder X-ray diffraction results confirmed that the prepared three products were at the Hexagonal phase of MoS2 with minor level of impurity. The SEM images show that the as-prepared structures have a Plate-like structure with sharped edges. Then the Linear sweep voltammetry of the materials verified that the high number of sharped edges of MoS2 nanocomposites leads to excellent activity for Hydrogen evaluation reaction (HER). When compared to others, 48 h material has a higher number of sharped edge sites and the best performances in HER. Finally, the sharpness and amounts of edge sites are possible to control with the duration of hydrothermal process and 2-H MoS2 with more number of sharped edge sites were found to increase the performances of HER

Species composition, abundance and distribution of butterflies in a home garden habitat located at Hanguranketha, Nuwara Eliya district, Sri Lanka

Sun, 01 Jan 2023 00:00:00 GMT

Title: Species composition, abundance and distribution of butterflies in a home garden habitat located at Hanguranketha, Nuwara Eliya district, Sri Lanka Authors: Rathnayake, R.R.M.U.N.B.; Karunarathna, D.S.; Dammini Premachandra, W.T.S. Abstract: The species richness, abundance and distribution of butterflies associated with a home garden, which was comprised of three micro-habitats; a grassland [GL], shrubland [SL] and disturbed-forest [DF], at Hanguranketha region, Nuwara Eliya district, was determined for a period of four months from September to December 2021, using a visual encounter survey. At each habitat, a belt transect (100 m x 10 m) was set up, and weekly observations were made within 20 minutes in the morning and the afternoon. Species diversity and the evenness were estimated using the Shannon-Weiner diversity index. A total of 32 species representing five families, Hesperiidae, Lycaenidae, Nymphalidae, Papilionidae and Pieridae were encountered. Two species were reported as endangered, while 10 were endemic sub-species. These families were observed in all the three habitats, with the exception of Papilionidae in the GL. Nymphalidae was the most diverse family in DF (35 %) and SL (48 %) whereas Lycaenidae and Nymphalidae made up the most diversity in the GL (37 %). The DF harbored the highest species richness (88 %) and GL had the lowest (34 %). Altogether, 873 individuals were detected over four months. The abundance was found to be similar (P>0.05) in the DF and SL, but lower (P<0.05) in the grassland compared to the other two habitats. The maximum relative abundance was detected (61 %) in the Nymphalidae, while Hesperiidae showed the second highest abundance. The highest diversity (H=2.91) was recorded in the DF with 0.876 in evenness. Butterfly counts in the morning hours outnumbered the evening hours (P<0.05). A reduction in butterfly counts (P<0.05) was detected during November and December. The findings of this study revealed that this home garden is rich in butterflies and proper conservation mechanisms are essentially needed to protect them.

Optimizing Phosphorus Solubilization Through Rhizosphere-Isolated Fungi

Sun, 01 Jan 2023 00:00:00 GMT

Title: Optimizing Phosphorus Solubilization Through Rhizosphere-Isolated Fungi Authors: Arachchi, W.A.D.B.W.; Jayaneththi, J.P.H.U.; Dissanayaka, D.M.S.H.; Amarasekara, M.G.T.S.; N.S., Abeysingha Abstract: Phosphate Solubilizing Microorganisms (PSMs) are capable of solubilizing insoluble forms of soil phosphate to liberate soluble P and make it available to plants. The growth and productivity of many different crops can be enhanced through these PSMs. Thus, introducing PSMs to seeds, crops, and soil is promising for promoting sustainable agriculture without endangering the environment. Hence this study was conducted to isolate and optimize the culture media for effective P solubilizing fungus. All experiments were conducted in laboratory conditions with a Complete Randomized Design (CRD) with three replicates. All the data were statistically analyzed using analysis of variance (ANOVA), and means were separated using Tukey’s HSD test. Four fungal strains were isolated from different plant rhizospheres of rice (1), maize (1), and chilli (2) plants as potential P solubilizers which produced a clear halo appearance. These fungal strains were tested for their capability on P solubilization by using phosphorus solubilizing index (PSI) in plates and the amount of solubilized P in broth cultures to identify the most effective P solubilizer. The selected fungus was further tested for media optimization. Different nitrogen (N), phosphorus (P), carbon (C) sources, and pH levels were optimized under in vitro conditions. One of the fungi isolated from chilli rhizosphere (Fd) was identified as the most effective P solubilizer with an established significantly highest solubilized P (2.54 ppm ± 0.13) and the average highest PSI (1.68). The media optimization study results showed that potassium di-hydrogen phosphate as P source, fructose as the C source, ammonium sulphate as the N source, and neutral pH (pH 7) could maximize the solubilization of P with Fd. Further improvements would be essential to introduce Fd as a P-solubilizing fungal inoculum to the soil.

Lepidopteran fauna of Mandaitivu Mangrove Ecosystem, Jaffna, Sri Lanka

Sun, 01 Jan 2023 00:00:00 GMT

Title: Lepidopteran fauna of Mandaitivu Mangrove Ecosystem, Jaffna, Sri Lanka Authors: G. W. A. L. K., Wijewantha; Gnaneswaran, R. Abstract: The mangrove forests, which support the survival of both terrestrial and aquatic inhabitants, are considered some of the most productive ecosystems. Mangrove faunal diversity is well known for the vertebrates and invertebrates but is poorly known for insects. Mangroves and insects have strong relationships in which mangroves provide a suitable habitat for insect habitation. In contrast, the feeding activities of insects contribute to the litter detritus formation and sustainability of the mangrove ecosystem. They connect mangroves with adjoined terrestrial and marine ecosystems by their eco-services such as pollination, herbivory, predation, and being food for other predators. Lepidopterans, consisting of moths and butterflies, are the most widely recognized insects as indicators of the ecosystem's health and are considered in conservation strategies. As the information on the Lepidopteran fauna of mangrove has not been revealed in Sri Lanka, this study was performed to explore the diversity of butterflies and moths in the Mandaitivu mangrove ecosystem from August 2019 to March 2020 located in the Northern Province of Sri Lanka. True mangrove species such as Avicennia marina, Rhizophora mucronata, Ceriops tagal and Pemphis acidula are distributed as patches around this island. Adult as well as larval stages of butterflies and moths were collected from two different locations based on the abundance of the mangrove vegetation at the west and south border of the Mandaitivu Island through sweep netting and handpicking methods. They were then identified based on their morphological characteristics. A total of 13 butterfly species, belonging to four families, and 6 moth species, belonging to three families were recorded. The highest species composition was recorded from Avicennia marina than Rhizophora mucronata which has fewer insects probably due to the thickness of their leaves. The plain tiger (Danaus chrysippus) was the most common and abundant butterfly followed by Mottled Emigrant (Catopsilia pyranthe) and the Small Salmon Arab (Colotis amata). The Yellow Pansy (Junonia hierta), the critically endangered (CR) species was also found. The other twelve species are listed as least concerned (LC) nationally. All the moth species recorded are listed as not assessed as per the IUCN red list. These results confirm that further extensive surveys in the Mandaitivu mangrove ecosystem will expose more diverse assemblages of lepidopterans that can be utilized in threat assessment and conservation strategy planning.