Synthesis and Characterization of Dibutyltin(IV) Comp)exes of Substituted Catechol

The complexes of dibutyltin (IV) with anions of 4-tert-buty1catechol, 4chlorocatechol, 4-nitrocatechol, 3,4-dihydroxybenzaldehyde, and 3,4dihydroxybenzoic acid were synthesized by reacting dibutyltin (IV) oxide with the corresponding free ligands. The isolated complexes were characterized by elemental analysis and spectroscopic methods such as infrared, lH and 13C NMR. Complex formation between the dibutyltin(IV) moiety and the anions of 4-tert-butylcatechol, 4-chlorocatechol, 4-nitrocatechol and 3,4dihydroxybenzaldehyde takes place with chelation at the o-hydroxy positions. However, results of analysis carried out on the dibutyltin (IV) complex of 3,4dihydroxybenzoic acid showed that the carboxylic group is also involved in chelate formation. Results of the lethality bioassay on the brine hrimp (Artemia salina) indicated that all the complexes have biological activity but only the 4tert- buty1catechol complex was able to cleave D A (plasmid pBR 322)

Magnetohydrodynamics flow past a moving vertical thin needle in a nanofluid with stability analysis

In this study, we intend to present the dynamics of a system based on the model of convective heat and mass transfer in magnetohydrodynamics (MHD) flow past a moving vertical thin needle in nanofluid. The problem is formulated in mathematical form by using Buongiorno’s model with the modified boundary condition. The transformed boundary layer ordinary differential equations are solved numerically using the bvp4c function in MATLAB software. The effects of the involved parameters, including, Brownian motion, thermophoresis, magnetic field, mixed convection, needle size and velocity ratio parameter on the flow, heat and mass transfer coefficients are analyzed. The numerical results obtained for the skin friction coefficients, local Nusselt number and local Sherwood number, as well as the velocity, temperature and concentration profiles are graphically presented and have been discussed in detail. The study reveals that the dual solutions appear when the needle and the buoyancy forces oppose the direction of the fluid motion, and the range of the dual solutions existing depends largely on the needle size and magnetic parameter. The presence of the magnetic field in this model reduces the coefficient of the skin friction and heat transfer, while it increases the coefficient of the mass transfer on the needle surface. A stability analysis has been performed to identify which of the solutions obtained are linearly stable and physically relevant. It is noticed that the upper branch solutions are stable, while the lower branch solutions are not

Current status of acute hepatopancreatic necrosis disease (AHPND) of farmed shrimp in Malaysia

A report about a disease problem in cultured whiteleg shrimp (Penaeus vannamei) was first received by the National Fish Health Research Center (NaFisH) in 2011 from Perak State showing signs of white feces and slow death leading to serious mortality rate. Later, in September of the same year, the Malaysian Shrimp Farmers Association (MSFA) reported to Department of Fisheries (DOF) severe mortalities in almost all of the whiteleg shrimp farms throughout Peninsular Malaysia. Sampling of shrimps for disease diagnosis was then conducted by NaFisH. The bacteriological and histopathological examinations revealed respectively the isolation of V. parahemolyticus and massive sloughing of hepatopancreatic epithelial cells. The disease was subsequently identified as acute hepatopancreatic necrosis disease (AHPND). From our 3-year study, the annual prevalence rates of AHPND were 50%, 26% and 73% in 2011, 2012 and 2013, respectively. At present, AHPND still persists in Malaysia but at a lower prevalence. The risk factors associated with the disease were studied, however, varied environmental and management data analyzed were inconclusive to relate any one parameter directly to the disease. To help ensure the early detection of AHPND, an experimental observation study on `gut scorecard was carried out and this was confirmed by PCR and histopathology. Validation of this technique has yet to be carried out to ensure its reliability. We also examined the potential use of some commercial products such as probiotics and disinfectants available in the market but unfortunately results showed that they were not effective in controlling AHPND. Control measures applied by the farmers such as the use of probiotics were also verified but data generated likewise appeared to be inconclusive. On the contrary, our preliminary study on the antibacterial property of the plant extracts, i.e. betel and lemongrass, incorporated in the feed showed some prophylactic and chemotherapeutic potential against AHPND. However, comprehensive in vitro and in vivo trials are still currently being undertaken to elucidate its efficacy and practical applications. To ensure the shrimp industry s sustainability in Malaysia, results of our ongoing and future studies aimed at preventing and controlling unwarranted outbreaks of AHPND and other emerging transboundary diseases of penaeid shrimps will be continually disseminated to shrimp farmers and pertinent stakeholders

Evaluation of efficient vehicular ad hoc networks based on a maximum distance routing algorithm

Traffic management at road intersections is a complex requirement that has been an important topic of research and discussion. Solutions have been primarily focused on using vehicular ad hoc networks (VANETs). Key issues in VANETs are high mobility, restriction of road setup, frequent topology variations, failed network links, and timely communication of data, which make the routing of packets to a particular destination problematic. To address these issues, a new dependable routing algorithm is proposed, which utilizes a wireless communication system between vehicles in urban vehicular networks. This routing is position-based, known as the maximum distance on-demand routing algorithm (MDORA). It aims to find an optimal route on a hop-by-hop basis based on the maximum distance toward the destination from the sender and sufficient communication lifetime, which guarantee the completion of the data transmission process. Moreover, communication overhead is minimized by finding the next hop and forwarding the packet directly to it without the need to discover the whole route first. A comparison is performed between MDORA and ad hoc on-demand distance vector (AODV) protocol in terms of throughput, packet delivery ratio, delay, and communication overhead. The outcome of the proposed algorithm is better than that of AODV

Spatial distribution and long-term persistence of Wolbachia-infected Aedes aegypti in the Mentari Court, Malaysia

Dengue is endemic in Malaysia, and vector control strategies are vital to reduce dengue transmission. The Wolbachia strain wAlbB carried by both sexes of Ae. aegypti was released in Mentari Court, a high-rise residential site, in October 2017 and stopped after 20 weeks. Wolbachia frequencies are still being monitored at multiple traps across this site, providing an opportunity to examine the spatiotemporal distribution of Wolbachia and mosquito density with respect to year, residential block, and floor, using spatial interpolation in ArcGIS, GLMs, and contingency analyses. In just 12 weeks, Wolbachia-infected mosquitoes were established right across the Mentari Court site with an overall infection frequency of >90%. To date, the Wolbachia frequency of Ae. aegypti has remained high in all areas across the site despite releases finishing four years ago. Nevertheless, the Wolbachia invaded more rapidly in some residential blocks than others, and also showed a relatively higher frequency on the eighth floor. The Ae. aegypti index tended to differ somewhat between residential blocks, whilst the Ae. albopictus index was relatively higher at the top and bottom floors of buildings. In Mentari Court, only a short release period was required to infiltrate Wolbachia completely and stably into the natural population. The results inform future releases in comparable sites in a dengue control programme

New Method of Depositing the Nanostructured Amorphous Carbon for Carbon Based Solar Cell Applications

Nanostructured amorphous carbon (a-C) solar cells were successfully deposited via a self-designed aerosol-assisted chemical vapor deposition (AACVD). The fabricated solar cell with the configuration of Au/p-C/n-Si/Au achieved efficiency () of % for device deposited at 500°C, % for 450°C, and % for 400°C. Photoresponse characteristic was highlighted under illumination (AM 1.5 illuminations: 100 mW/cm2, 25°C), where conductivity increased when the sample was being hit by light. Transmittance spectrum exhibits a large transmittance value (85%) and absorption coefficient value of  cm−1 at the visible range from 390 to 790 nm. The nanostructured a-C thin film deposited at higher temperature possesses lower transmittance due to higher absorption as a result of the higher content of sp2-bonded carbon atoms. From Tauc’s plot, optical band gap () was determined, and decreased as deposition temperature increased (1.2 eV, 1.0 eV, 0.7 eV). On the other hand, FESEM images exhibited a nanostructured sized a-C with the particle size less than 100 nm. To the best of our knowledge, the presence of nanostructured particle of a-C by a self-prepared AACVD has not frequently been reported

The boundary element method in contiguous domains

As an example of a problem involving two finite contiguous domains, the boundary element method is used to compute the eddy current density in a conductor subjected to a transverse magnetic field

Pattern of Childhood Fractures in a Developing Country

INTRODUCTION: Trauma is a major cause of childhood morbidity, and pattern of fractures in children is related to socioeconomic and environment factors. We conducted this study to look at fracture pattern of children in a developing country. MATERIAL AND METHOD: Children aged 12 and below who attended paediatric orthopaedic out-patient clinic between July 2009 and March 2010 were enrolled for the study. Information was collected by interview that was based on a questionnaire. RESULTS: There were 260 children in the study, and 72.3% were boys. The most common bone fractured was the radius and/or ulnar (41.9%), followed by the humerus (27.7%) and tibia/fibula (7.7). Most common place for fracture to happen was at home (35.5%), followed by in the parks (17.3%) and at school (15.7%). Road traffic accident only contributed 9.2% of all the fractures. Of the 25 fractures due to road traffic accidents, 16 involved the use of vehicles. About one third (36.73%) of the injuries were not witnessed. One quarter (24.9%) were witnessed by parents and one fifth (17.1%) witnessed by siblings. Conclusion: Upper limb are more commonly fractures than lower limbs. Measures to reduce the problem should start at home by creating higher awareness on injury prevention among the parents

Unmanned aerial vehicle applications in agriculture

Agriculture becomes extremely important as a main source of food production to feed the population in this planet. On the other hand, agriculture provides a lot of benefits to the country such as food and non-food product, transportation and balancing the environment. The demand for food security creates pressure to the decision maker to ensure our world has sufficient food for the entire world. Thus, the usage of the unmanned aerial vehicle (UAV) is an alternative to manage a farm properly to increase its yield. In order to promote the use of UAV in agriculture to support its sustainability, this paper provides an understanding towards the usage of UAV and its applications in agriculture. The objective of this paper is to review the usage of UAV in agriculture applications. Based on the literature, we found that a lot of agriculture applications can be done by using UAV. In the methodology, we used a comprehensive review from other researches in this world. As a result, from the revision, we found that different sensors give different analysis to the agriculture applications. Thus, the purpose of the project needs to be investigated before using the UAV technology for better data quality and analysis. As a conclusion, a suitable sensor and UAV need to be identified before using UAV to gather accurate data and precise analysis

MHD flow of hybrid nanofluid past a stretching sheet: double stratification and multiple slips effects

Studies of hybrid nanofluids flowing over various physical geometries and conditions are popular among researchers to understand the behavior of these fluids. Thenceforth, the numerical solutions for hybrid Ag-CuO/H2O nanofluid flow over a stretching sheet with suction, magnetic field, double stratification, and multiple slips effects are analyzed in the present study. Governing equations and boundary conditions are introduced to describe the flow problem. Then, similarity variables are applied to transform the equations into non-linear ordinary differential equations and boundary conditions. The numerical computation for the problem is done in Matlab (bvp4c solver), and the results are presented in tables and graphs. It is found that the rise in solutal slip and stratification parameters reduces the Sherwood number. Meanwhile, the increase in thermal slip and stratification parameters lowers the Nusselt number. The skin friction coefficient is observed to increase with the augmentation of the hydrodynamic slip parameter