Optical mode size control by MgO indiffusion in Ti:LiNbO3 waveguides

In this paper, the use of magnesium oxide (MgO) indiffusion in combination with Ti:LiNbO<sub>3</sub> through appropriate control of pre- and post-diffusion parameters is investigated as a way of controlling optical mode size. The co-diffusion of pre-patterned Ti with various patterned MgO films on LiNbO<sub>3</sub> has been compared experimentally. This method has been applied to study straight waveguides and couplers. The waveguides were optically characterized by near-field mode size and loss measurements methods at a wavelength of 1.55 μm. Reduction of inter-mode coupling between adjacent waveguides with the introduction of MgO has been observed

Long-term assessment of surface water quality in a highly managed estuary basin

Anthropogenic developments in coastal watersheds cause significant ecological changes to estuaries. Since estuaries respond to inputs on relatively long time scales, robust analyses of long-term data should be employed to account for seasonality, internal cycling, and climatological cycles. This study characterizes the water quality of a highly managed coastal basin, the St. Lucie Estuary Basin, FL, USA, from 1999 to 2019 to detect spatiotemporal differences in the estuary’s water quality and its tributaries. The estuary is artificially connected to Lake Okeechobee, so it receives fresh water from an external basin. Monthly water samples collected from November 1999 to October 2019 were assessed using principal component analysis, correlation analysis, and the Seasonal Kendall trend test. Nitrogen, phosphorus, color, total suspended solids, and turbidity concentrations varied sea-sonally and spatially. Inflows from Lake Okeechobee were characterized by high turbidity, while higher phosphorus concentrations characterized inflows from tributaries within the basin. Differences among tributaries within the basin may be attributed to flow regimes (e.g., significant releases vs. steady flow) and land use (e.g., pasture vs. row crops). Decreasing trends for orthophosphate, total phosphorus, and color and increasing trends for dissolved oxygen were found over the long term. Decreases in nutrient concentrations over time could be due to local mitigation efforts. Understanding the differences in water quality between the tributaries of the St. Lucie Estuary is es-sential for the overall water quality management of the estuary

Anammox Process for Removal of Ammonia from Landfill Leachate

Landfilling is a common practice used to dispose municipal solid waste due to economic considerations in developing countries as Sri Lanka. Among the different ways of landfilling, open pit dumping can be identified as the worst case which creates severe impacts on environment. Major impact which was reported over the years is the contamination of ground and surface water. This highly contaminated waste water which comes through landfills, are called landfill leachate. Since, leachate is directly unveiled to the environment, proper treatment should be carried out prior to dispose. Composition of leachate varies with time. Testing of this research based on Karadiyana Dump site, Sri Lanka and it is recorded that contamination of water in terms of ammonia, nitrite and phosphorous as 700-900 mg/L, 60-126 mg/L and 33-66 mg/L respectively. Also, in Karadiyana high LPI value of 28.88 was indicated. Conventional as well as innovative treatment methods are used to treat leachate. In recent past, many innovative techniques were discovered by scientists to treat leachate. Anammox process is one of the major findings to treat high nitrogen loaded wastewater. Conventional nitrification requires high aeration and dentrification requires high carbon sources. Hence, conventional techniques incurred higher cost. Reduction of oxygen consumption by 60% and no additional carbon source requirement can be identified as dominant advantages over conventional nitrification/denitrification process comparing with anammox process. Anammox bacteria were enriched by applying synthetic wastewater under anaerobic condition in a sequencing batch reactor (SBR). After successful enrichment of anammox bacteria, reactor was set to 32+0.5o C and pH 7.5 with HRT of 4 days for anammox process. After a successful anammox process that partially treated wastewater was set to flow through bio char barricades and thereafter through a constructed wetland. 99% ammonia removal as well as 98% of nitrite removal was identified during 25 days of testing period. Further, 82% of prosperous removal also was recorded. Addition to those, 65% of COD removal was obtained. Additional development can be done to anammox process since nitrite is an intermediate component for both nitrifiction and denitrification. This partial nitritation (PN) prior to anammox treatment can be performed in a Single reactor for High activity Ammonia Removal Over Nitrite (SHARON). Main objective of PN is to achieve stoichiometric ratio between ammonia nitrogen to nitrite nitrogen for better anammox process. According to the anammox reaction this ratio should be 1:1.32 between ammonium nitrogen to nitrite nitrogen under aerobic condition and ammonium oxidizing bacteria (AOB) have to be prepared prior to the process. Sludge taken from an aeration tank can be used to enrich AOB. And this combined process is called PN-Anammox.Keywords: Anammox, Leachate treatment, Partial nitratio

Globular cluster population of the HST frontier fields galaxy J07173724+3744224

We present the first measurement of the globular cluster population surrounding the elliptical galaxy J07173724+3744224 (z=0.1546). This galaxy is located in the foreground in the field-of-view of the Hubble Space Telescope (HST) Frontier Fields observations of galaxy cluster MACS J0717.5+3745 (z=0.5458). Based on deep HST ACS F435W, F606W, and F814W images, we find a total globular cluster population of N_tot = 3441 +/- 1416. Applying the appropriate extinction correction and filter transformation from ACS F814W to the Johnson V-band, we determine that the host galaxy has an absolute magnitude of M_V = -22.2. The specific frequency was found to be S_N = 4.5 +/- 1.8. The radial profile of the globular cluster system was best fit using a powerlaw of the form $\sigma\sim R^{-0.6}$, with the globular cluster population found to be more extended than the halo light of the host galaxy ($\sigma_{halo}\sim R^{-1.7}$). The F435W-F814W colour distribution suggests a bimodal population, with red globular clusters 1-3x more abundant than blue clusters. These results are consistent with the host elliptical galaxy J07173724+3744224 having formed its red metal-rich GCs in situ, with the blue metal-poor globular clusters accreted from low-mass galaxies.Comment: 21 pages, 14 figures, 2 tables, revised following peer-review, accepted for publication in MNRA

Municipal solid waste biochar-bentonite composite for the removal of antibiotic ciprofloxacin from aqueous media

This study investigates the adsorption of ciprofloxacin (CPX) onto a municipal solid waste derived biochar (MSW-BC) and a composite material developed by combining the biochar with bentonite clay. A bentonite-MSW slurry was first prepared at 1:5 ratio (w/w), and then pyrolyzed at 450 °C for 30 min. The composite was characterized by scanning electron microscopy (SEM), Powder X-ray diffraction (PXRD) and Fourier transform infrared (FTIR) spectroscopy before and after CPX adsorption. Batch experiments were conducted to assess the effect of pH, reaction time and adsorbate dosage. The SEM images confirmed successful modification of the biochar with bentonite showing plate like structures. The PXRD patterns showed changes in the crystalline lattice of both MSW-BC and the composite before and after CPX adsorption whereas the FTIR spectra indicated merging and widening of specific bands after CPX adsorption. The optimum CPX adsorption was achieved at pH 6, and the maximum adsorption capacity of the composite calculated via isotherm modeling was 190 mg/g, which was about 40% higher than the pristine MSW-BC. The Hill isotherm model along with pseudo-second order and Elovich kinetic models showed the best fit to the adsorption data. The most plausible mechanism for increased adsorption capacity is the increased active sites of the composites for CPX adsorption through induced electrostatic interactions between the functional groups of the composite and CPX molecules. The added reactive surfaces in the composite because of bentonite incorporation, and the intercalation of CPX in the clay interlayers improved the adsorption of CPX by the biochar-bentonite composite compared to the pristine biochar. Thus, MSW-BC-bentonite composites could be considered as a potential material for remediating pharmaceuticals in aqueous media

An irrigated area map of the world (1999) derived from remote sensing

Remote sensing / Mapping / GIS / Irrigated sites / Estimation

The use of transient electro-magnetism method to localize saline water intrusion in Sri Lanka

On the east coast of Sri Lanka, groundwater resources mainly consist in coastal aquifers, which are exploited for both irrigation and domestic purposes. In case of an intensive exploitation, saline water intrusions can occur, which make the water in wells improper for consumption. Considering the future resettlements of internally displaced families in coastal areas, and in order to evaluate the potential of these coastal aquifers (before launching a well implementation program), one need to locate the extent of this saline water intrusion. This information can be obtained by intrusive means such as piezometers monitoring, or non-intrusive means with geophysical methods. Transient Electro Magnetism (TEM) method has been used on different coastal sites on the east coast of Sri Lanka and has given good results for estimating the aquifers geometrical parameters. This first study will be followed by a more complete geophysical survey involving other methods

Heavy Metal-Induced Oxidative Stress on Seed Germination and Seedling Development: A Critical Review

Heavy metal contamination in soils can influence plants and animals, often leading to toxicosis. Heavy metals can impact various biochemical processes in plants, including enzyme and antioxidant production, protein mobilization and photosynthesis. Hydrolyzing enzymes play a major role in seed germination. Enzymes such as acid phosphatases, proteases and α-amylases are known to facilitate both seed germination and seedling growth via mobilizing nutrients in the endosperm. In the presence of heavy metals, starch is immobilized and nutrient sources become limited. Moreover, a reduction in proteolytic enzyme activity and an increase in protein and amino acid content can be observed under heavy metal stress. Proline, is an amino acid which is essential for cellular metabolism. Numerous studies have shown an increase in proline content under oxidative stress in higher plants. Furthermore, heat shock protein production has also been observed under heavy metal stress. The chloroplast small heat shock proteins (Hsp) reduce photosynthesis damage, rather than repair or help to recover from heavy metal-induced damage. Heavy metals are destructive substances for photosynthesis. They are involved in destabilizing enzymes, oxidizing photosystem II (PS II) and disrupting the electron transport chain and mineral metabolism. Although the physiological effects of Cd have been investigated thoroughly, other metals such as As, Cr, Hg, Cu and Pb have received relatively little attention. Among agricultural plants, rice has been studied extensively; additional studies are needed to characterize toxicities of different heavy metals on other crops. This review summarizes the current state of our understanding of the effects of heavy metal stress on seed germination and seedling development and highlights informational gaps and areas for future research

Phytoremediation Using Constructed Wetlands to Treat Reverse Osmosis Rejected Concentrates

Reverse Osmosis (RO) water purification systems are common over many farming areas of North Central Province in Sri Lanka for providing potable water to protect public from the Chronic Kidney Disease of unknown etiology (CKDu). About 50-70% of raw water with higher concentrations of ions release from RO systems with no beneficial use. Such a practice will end up with long term environmental impacts to soil and groundwater and therefore it is at utmost requirement to find suitable remedial technique. This research was focused to investigate the potential remedial measures for concentrated contaminants of RO rejected water through phytoremediation process using Constructed Wetlands (CW), before discharging into the environment.A field experiment was carried out focusing on the Sangilikanadarawa at Medawachchiya community based RO water supply unit. Two types of constructed wetlands (CW): surface and subsurface water bio-geo CW were established and tested to measure the removal efficiency of RO concentrates through phytoremediation and filter materials. Locally available soil, Calicut tile and biochar were used with proportions of 81, 16.5 and 2.5% by weight respectively as filter materials. Vertiver Grass and Scirpus Grossus were carefully selected for the sub surface wetland while Water Lettuce and Water Hyacinth were chosen for free water surface CW. Both constructed wetlands were fed with a uniform flow of RO concentrate and water quality parameters were tested periodically against two controls systems for a given hydraulic retention time. The results showed that the Total Dissolved Solids, Hardness, Total Alkalinity and Fluoride were reduced significantly and met desirable levels of stipulated ambient standards. This study indicated a great promise of purifying aforesaid contaminants of water which is obvious and considerable in ground water sources in the North Central Province, with a very low construction and maintenance cost in comparison to other water purifying methods as this approach directly dealt with locally available aquatic plants and ecofriendly filter materials. Therefore the invented bio-geo constructed wetland is an economical and effective option for reducing high concentrations of RO rejected water before discharging into the inland waters.Keywords: Reverse osmosis, RO concentrate, Phytoremediation, Constructed wetlands, biocha

IS THE LEVEL OF ENTREPRENEURIAL ORIENTATION VARIED ACROSS THE DIFFERENT SECTORS OF INDUSTRY?

Sri Lanka is a developing country with a gradually but slowly increasing annual income. Moreover, it shows a great potential for a rapid growth if the performance of business, specially, Small and Medium Enterprises could be improved since in comparison to the performance of SMEs of the most of other Asian countries Sri Lankan Small and Medium Enterprises are lagging behind in term of performance. As per the Asian Productivity Organization, developing the degree of entrepreneurship is one of the highly viable strategies for ensuring growth of Asian economies. Despite, whether the Entrepreneurial Orientation of Small and Medium Enterprises varies among the different industrial sectors, i.e. Manufacturing, Services and Trade, is remained untouched. The dearth of research hinders the efforts of interested parties to improve the performance of Small and Medium Enterprises. Hence, future research would be useful to the academia and policy makers to uncover more productive and country specific strategies to inspire entrepreneurial orientation of local Small and Medium Enterprises. Accordingly, this article focuses on how the variation of entrepreneurial orientation is varies among different sectors of Small and Medium Enterprises of Sri Lanka. The results of the study indicated that there is no significant difference of entrepreneurial orientation among different sectors.  Article visualizations