Herbicidal activity of Pennisetum purpureum (Napier grass)

This study investigates potential herbicidal effects of Pennisetum purpureum extracts on two selected weed bioassay species. Ethyl acetate extract of P. purpureum was able to suppress germination of bioassay species by 41%. Although, it had no phytotoxic activity on the root or shoot growth of bioassay species, it had caused leaf discs of bioassay species to turn dark brown. Chromatographic separation of ethyl acetate extract yielded nine fractions. The highest suppressive ability was exhibited by fraction five where the shoot and root growth of bioassay species was inhibited markedly, while the colour of leaf discs changed from green to dark brown. The germination of the bioassay species is particularly sensitive to the fraction five, exhibiting approximately 20% reduction in germination, relative to the control. These results imply that P. purpureum contains phytotoxic compounds that can be developed as natural herbicide.Key words: Pennisetum purpureum extracts, allelochemicals, phytotoxic, bioassay

Speciation of heavy metals in paddy soils from selected areas in Kedah and Penang, Malaysia

This study was carried out with the intention of evaluating heavy metal contamination in cultivated paddy areas. The speciation of heavy metals in paddy soils was determined in order to gain insight regarding their origin and distribution in soils. Five sampling sites were randomly selected from Kedah (Yan, Kota Setar, Kubang Pasu district) and Penang (Bumbung Lima district), where the soils constituted marine alluvial deposits. A site in Langkawi, where organic paddy farming is practised was used as the control. The sequential extraction method was adopted in order to obtain the four heavy metal fractions namely the easily leachable and ion exchange (ELFE), acid reducible (AR), oxidizable organic (OO) and resistant (RR) fractions. This study shows that the soil samples were clayey (82 to 96% of grain size <63 μm), fairly high in organic carbon (6.54 to 8.71%) and slightly acidic (pH 4.92 to 5.12). Heavy metal content in the soils varied widely and occurred in the following decreasing order of Fe>Mn>Cr>Cd>Pb>Zn>Cu. Heavy metals such as Pb, Cu, Cr and Zn predominantly occurred in the insoluble form (RR fraction), with the oxides of Fe and Mn incorporated into the clay minerals. Although, the fertilizers and pesticides studied contained low amounts of heavy metals, the elevated amount of amount of Mn and Cd in the soils (ELFE fraction) could possibly be attributed to the longterm and repeated application of these materials to the cultivated paddy areas.Key words: Heavy metals, paddy soil, pesticide, fertilizer

Post-operative Day 1 versus Day 0 follow-up for Uncomplicated Cataract Surgeries: A comparison of post-operative outcomes and managements

Purpose: To compare the postoperative outcomes and management of uncomplicated cataract surgery (CEIOL) patients seen on post-operative day zero (POD 0) versus post-operative day one (POD 1). Methods: A retrospective chart review of 533 patients who had CEIOL at the Kresge Eye Institute from December 2017 to September 2019 was performed. Visual acuity (VA) and intraocular pressure (IOP) were collected from the pre-operative visit, and the first and second post-operative day visits. In addition, changes in management were recorded from the first post-operative day visit. Patients were excluded if they had a complex cataract procedure, had combined glaucoma filtering surgery, or did not complete two follow up visits within 14 days of surgery. Results: The pre-operative demographic data between patients seen on POD 0 (n=119) versus POD1 (N=414) were equally distributed. By unpaired t-test, the average VA of patients seen on POD 1 was significantly better than those seen on POD 0 (P0.50). Conclusion: There was no significant difference in management between POD 0 and POD 1 patients having undergone uncomplicated cataract surgeries. Therefore, surgeons can safely consider POD 0 or POD 1 evaluations for uncomplicated cataract surgeries and improve healthcare cost efficiency for CEIOL

QoS analysis of the MANET routing protocols with respect to delay, throughput, & network load: Challenges and open issues

Mobile Ad Hoc Networks (MANETs) are types of wireless networks that communicate with mobile devices without centralized infrastructures. MANET networks are established through interconnected devices that communicate wirelessly within a relatively small, shared area. In MANET every single mobile node is presumed to travel in all directions at different speeds with challenges and open issues. Hence there is no guaranteed long-term path from one node to the next. This work proposes testing the three most common ad hoc routing protocols Ad-hoc On-demand Distance Vector (AODV), Dynamic Source Routing (DSR) and Optimized Link State Routing Protocol (OLSR) using Optimized Network Engineering Tool (OPNET) Modeler simulations using the performance metrics of Throughput, Delay, and Network loading to find an effective routing protocol for routing. The traffic network is used by the File Transfer Protocol (FTP), Digital Education, Battlefield, Surveillance and Security Agencies may benefit from the research work. MANETs reduced the costs of installation, maintenance and operation of such facilities as base stations and also reduced the risk to a minimum such as pollution. The outcome of the simulation shows that: according to the AODV and DSR, the lowest delay in 50 nodes was around 31.25 seconds respectively. And OLSR also had a high throughput performance of around 80 per cent compared with AODV and DSR. And it can be concluded that OLSR is the most suitable routing protocol for MANET, based on the routing protocols suggested

Seasonal distribution of anti-malarial drug resistance alleles on the island of Sumba, Indonesia

Background: Drug resistant malaria poses an increasing public health problem in Indonesia, especially eastern Indonesia, where malaria is highly endemic. Widespread chloroquine (CQ) resistance and increasing sulphadoxine-pyrimethamine (SP) resistance prompted Indonesia to adopt artemisinin-based combination therapy (ACT) as first-line therapy in 2004. To help develop a suitable malaria control programme in the district of West Sumba, the seasonal distribution of alleles known to be\ud associated with resistance to CQ and SP among\ud Plasmodium falciparum isolates from the region was investigated.\ud Methods: Plasmodium falciparum isolates were collected during malariometric surveys in the wet and dry seasons in 2007 using two-stage cluster sampling. Analysis of pfcrt, pfmdr, pfmdr1 gene copy number, dhfr, and dhps genes were done using protocols described previously.\ud Results and Discussion: The 76T allele of the pfcrt gene is nearing fixation in this population. Pfmdr1 mutant alleles occurred in 72.8% and 53.3%, predominantly as 1042D and 86Y alleles that are mutuallyexclusive. The prevalence of amplified\ud pfmdr1 was found 41.9% and 42.8% of isolates in the wet and dryseasons, respectively. The frequency of dhfr mutant alleles was much lower, either as a single 108N mutation or paired with 59R. The 437G allele was the only mutant dhps allele detected and it was only found during dry season.\ud Conclusion: The findings demonstrate a slighly higher distribution of drug-resistant alleles during the wet season and support the policy of replacing CQ with ACT in this area, but suggest that SP might still be effective either alone or in combination with other anti-malarial

Influence of slag composition on the stability of steel in alkali-activated cementitious materials

Among the minor elements found in metallurgical slags, sulfur and manganese can potentially influence the corrosion process of steel embedded in alkali-activated slag cements, as both are redox-sensitive. Particularly, it is possible that these could significantly influence the corrosion process of the steel. Two types of alkali-activated slag mortars were prepared in this study: 100% blast furnace slag and a modified slag blend (90% blast furnace slag? 10% silicomanganese slag), both activated with sodium silicate. These mortars were designed with the aim of determining the influence of varying the redox potential on the stability of steel passivation under exposure to alkaline and alkaline chloride-rich solutions. Both types of mortars presented highly negative corrosion potentials and high current density values in the presence of chloride. The steel bars extracted from mortar samples after exposure do not show evident pits or corrosion product layers, indicating that the presence of sulfides reduces the redox potential of the pore solution of slag mortars, but enables the steel to remain in an apparently passive state. The presence of a high amount of MnO in the slag does not significantly affect the corrosion process of steel under the conditions tested. Mass transport through the mortar to the metal is impeded with increasing exposure time; this is associated with refinement of the pore network as the slag continued to react while the samples were immersed

A meta-analysis of long-term effects of conservation agriculture on maize grain yield under rain-fed conditions

Conservation agriculture involves reduced tillage, permanent soil cover and crop rotations to enhance soil fertility and to supply food from a dwindling land resource. Recently, conservation agriculture has been promoted in Southern Africa, mainly for maize-based farming systems. However, maize yields under rain-fed conditions are often variable. There is therefore a need to identify factors that influence crop yield under conservation agriculture and rain-fed conditions. Here, we studied maize grain yield data from experiments lasting 5 years and more under rain-fed conditions. We assessed the effect of long-term tillage and residue retention on maize grain yield under contrasting soil textures, nitrogen input and climate. Yield variability was measured by stability analysis. Our results show an increase in maize yield over time with conservation agriculture practices that include rotation and high input use in low rainfall areas. But we observed no difference in system stability under those conditions. We observed a strong relationship between maize grain yield and annual rainfall. Our meta-analysis gave the following findings: (1) 92% of the data show that mulch cover in high rainfall areas leads to lower yields due to waterlogging; (2) 85% of data show that soil texture is important in the temporal development of conservation agriculture effects, improved yields are likely on well-drained soils; (3) 73% of the data show that conservation agriculture practices require high inputs especially N for improved yield; (4) 63% of data show that increased yields are obtained with rotation but calculations often do not include the variations in rainfall within and between seasons; (5) 56% of the data show that reduced tillage with no mulch cover leads to lower yields in semi-arid areas; and (6) when adequate fertiliser is available, rainfall is the most important determinant of yield in southern Africa. It is clear from our results that conservation agriculture needs to be targeted and adapted to specific biophysical conditions for improved impact

Overlapping Community Discovery Methods: A Survey

The detection of overlapping communities is a challenging problem which is gaining increasing interest in recent years because of the natural attitude of individuals, observed in real-world networks, to participate in multiple groups at the same time. This review gives a description of the main proposals in the field. Besides the methods designed for static networks, some new approaches that deal with the detection of overlapping communities in networks that change over time, are described. Methods are classified with respect to the underlying principles guiding them to obtain a network division in groups sharing part of their nodes. For each of them we also report, when available, computational complexity and web site address from which it is possible to download the software implementing the method.Comment: 20 pages, Book Chapter, appears as Social networks: Analysis and Case Studies, A. Gunduz-Oguducu and A. S. Etaner-Uyar eds, Lecture Notes in Social Networks, pp. 105-125, Springer,201

Structure-Based Vaccines Provide Protection in a Mouse Model of Ehrlichiosis

infection. were protected against the pathogen.Our results demonstrate the power of structural vaccines and could be a new strategy in the development of vaccines to provide protection against pathogenic microorganisms