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A new species of Haliotrema (Monogenea: Ancyrocephalidae (sensu lato) Bychowsky & Nagibina, 1968) from holocentrids off Langkawi Island, Malaysia with notes on the phylogeny of related Haliotrema species
No full textHaliotrema susanae sp. nov. is described from the gills of the pinecone soldierfish, Myripristis murdjan off Langkawi Island, Malaysia. This species is differentiated from other Haliotrema species especially those from holocentrids in having a male copulatory organ with bract-like extensions at the initial of the copulatory tube, grooved dorsal anchors and ventral anchors with longer shafts. The maximum likelihood (ML) analysis based on partial 28S rDNA sequences of H. susanae sp. nov. and 47 closely related monogeneans showed that H. susanae sp. nov. is recovered within a monophyletic clade consisting of only species from the genus Haliotrema. It is also observed that H. susanae sp. nov. forms a clade with H. cromileptis and H. epinepheli which coincides with a similar grouping by Young based on solely morphological characteristics. The morphological and molecular results validate the identity of H. susanae sp. nov. as belonging to the genus Haliotrema
Effect of multi-ions doping on the properties of carbonated hydroxyapatite bioceramic
No full textThe effect of multi-ions (Mg2+, SiO4 4-, Zn2+, Cu2+) doping on the properties of carbonated hydroxyapatite (CHA) prepared by a wet chemical method has been investigated. Different combinations of ions were doped into the CHA and the as-synthesized compacts were sintered at 900 °C prior to body characterization. It was found that regardless of ions doping, the lattice structure of the CHA was not disrupted. In addition, secondary phases were not detected for all the multi-ions doped samples. The XRD and FTIR results further confirmed the presences of a B-Type CHA in the sintered samples. The XRD analysis revealed that the lattice parameters (c/a ratio) increased with dopant addition and resulted in a smaller crystallite size. The FESEM examination also showed the presences of smaller grain size for the multi-ions doped CHA samples thus indicating that the doping was beneficial in suppressing grain coarsening in carbonated hydroxyapatite
Assessment of allelopathic potential of goniothalamin allelochemical from Malaysian plant Goniothalamus andersonii J. Sinclair by sandwich method
No full textWe evaluated the allelopathic potentials of 145 plant species collected from several locations in Malaysia using the sandwich method. Among them, the bark of Goniothalamus andersonii J. Sincl. proved most inhibitory to radicle growth of lettuce seedlings, followed by leaves of Ageratum conyzoides L. (Asteraceae), Amaranthus spinosus L. (Amaranthaceae) and Goniothalamus longistipites Mat Salleh (Annonaceae) bark. Goniothalamin was identified as the potent allelochemical from the bark of G. andersonii. The EC50 value of goniothalamin against the growth of lettuce radicles was 50 µmol L-1. The total activity of goniothalamin was maximum on the growth of lettuce than other allelochemicals [6-O-(4’-hydroxy-2’-methylene-butyroyl)-1-O-cis-cinnamoyl-β-D-glucopyranose (BCG), L-3,4-dihydroxyphenylalanine (L-DOPA) and 1-O-cis-cinnamoyl-β-D-glucopyranose (cis-CG)]
Physical properties of ethylene glycol-based deep eutectic solvents
No full textDeep eutectic solvents (DESs) have been widely recognized as ionic liquids (ILs) analogues due to their low production cost and superior favorable properties over conventional ILs. Studying the physical properties of these solvents will contribute to design processes involving DESs. In this study, five DESs have been successfully prepared using ethylene glycol (EG) as hydrogen bond donor (HBD) with N,N‑diethylethanolammonium chloride (DAC), benzyltriphenylphosphonium chloride (BTPC), choline chloride (ChCl), methyltriphenylphosphonium bromide (MTPB) and tetra‑n‑butylammonium bromide (TBAB) as salts. The freezing point of each of the five studied DESs was measured using Differential Scanning Calorimetry (DSC) and the DES functional groups were identified using the Fourier transform infrared (FTIR) spectroscopy. Moreover, the viscosity, density, electrical conductivity and surface tension were measured at a temperature range of 293.15–353.15 K and they were highly affected by the variation of the temperature. It is worth mentioning that the studied DESs showed many physical characteristics similar to that of ILs, which boost their possibilities to be employed in interdisciplinary domains
Synthesis of new low-viscous sulfonic acid-functionalized ionic liquid and its application as a Brönsted liquid acid catalyst for the one-pot mechanosynthesis of 4H-pyrans through the ball milling process
No full textIn the present study, a new low-viscous sulfonic acid-functionalized ionic liquid (SAIL) viz. 4,4′-trimethylene-N,N′-sulfonic acid-dipiperidinium chloride was synthesized and characterized by FTIR, 1D and 2D NMR, and Mass spectra. Then, some properties of new SAIL were determined including pH, viscosity, density, and solubility in some common solvents. The catalytic activity of new SAIL was demonstrated for the one-pot mechanosynthesis of pyrano[4,3-b]pyrans, dihydropyrano[3,2-c]chromene and tetrahydrobenzo[b]pyrans using planetary ball mill under solvent-free conditions. This current mechanosynthesis methodology for the synthesis of 4H-pyran-annulated heterocyclic scaffolds displays a combination of the synthetic virtues of conventional multi-component reaction with ecological benefits and convenience of a simple mechanocatalytic procedure. New SAIL was easily recycled and reused several times with no significant loss of activity
Electronic, optical, elastic, thermoelectric and thermodynamic properties of the spinel oxides ZnRh2O4 and CdRh2O4
No full textDensity functional FP-LAPW+lo method calculations were performed to explore the structural, electronic, optical, elastic, thermoelectric and thermodynamic properties of the spinel oxides ZnRh2O4 and CdRh2O4. The exchange-correlation potential were described using the GGA-PBEsol and TB-mBJ functionals. As the first step, the optimized structural parameters, including the lattice parameter and atomic coordinates, were determined. Electronic band structure, atomic-resolved l-projected densities of electronic states and photon energy dependence of the linear optical functions were computed. It is found that both investigated compounds are indirect band gap semiconductors. The band gap results from the splitting of the Rh:4d6 states into occupied Rh:4d−t2g 6 states, which form the valence band maximum (VBM), and the empty states Rh:4d−eg 0, which form the conduction band minimum (CBM), owing to the octahedral substantial crystal-field. The electronic interband transitions responsible of the structures in the optical spectra were specified. Single-crystal and polycrystal elastic moduli, wave sound velocities, Debye temperature, Pugh's indicator and indexes of elastic anisotropy were numerically estimated using total energy versus strain. FP-LAPW+lo band structure in combination with the standard Boltzmann transport theory were employed to calculate the thermoelectric parameters, including Seebeck coefficient, electrical and thermal conductivities and figure of merit. It is found that the title compounds are potential candidates for thermoelectric applications if one can further reduce their thermal conductivities via some techniques. FP-LAPW+lo approach in combination with the quasi-harmonic Debye model was employed to study temperature and pressure dependences of some macroscopic physical parameters. Our obtained results in the present work are discussed in comparison with the available experimental and theoretical data. The calculated results show a good agreement with the available experimental and theoretical results
Investigation of the interaction of levofloxacin hemihydrate with surfactants in the occurrence of salts: Conductivity and cloud point measurement
No full textConductometric and cloud point (CP) measurement techniques have been employed in order to investigate the interaction of antibiotic drug levofloxacin hemihydrate (LFH) with anionic surfactant, sodium dodecyl sulfate (SDS) as well as a non-ionic surfactant Tween-80 (Tw-80; polyethylene sorbitol ester) in the absence/occurrence of various salts over the temperature range 298.15–318.15 K keeping regular interval of 5 K. Two clear c* values were extracted for pure SDS along with (SDS + LFH) mixtures where the increase and decrease of c* values due to the addition of LFH and salts respectively demonstrated the happened interaction among the studied components where salts provided a convenient environment for aggregation of surfactants. Negative ∆G°m values of SDS in H2O/(SDS + LFH) mixtures revealed the spontaneous assembling of surfactant molecules and the stability of the aggregates. The values of ∆H°m and ∆S°m indicate the existence of hydrophobic & electrostatic interactions between drug (LFH) and surfactant (SDS). Enthalpy and entropy contributions on the standard free energy of micellization were also calculated. The CP magnitudes of Tween-80 were reduced with increasing its concentration. The occurrence of LFH/(LFH + salts) boosted to lessening the CP values. The positive ∆G°c values suggested the non-spontaneity of clouding while the obtained ∆H°c and ∆S°c values of this CP study demonstrated the two significant accelerating impacts (electrostatic/hydrophobic interactions) between LFH & Tw-80. The thermodynamic properties of transfer for both techniques were also evaluated and analyzed in detail in the current study
Process state synchronization-based application execution management for mobile edge/cloud computing
No full textMobile cloud computing (MCC) and mobile edge computing (MEC) facilitate the mobile devices to augment their capabilities by utilizing the resources and services offered by Cloud and Edge Cloud, respectively. However, due to mobility, network connection becomes unstable that causes application execution disruption. Such disruption increases the execution time and in some cases restrain the mobile devices from getting execution results from the cloud. This research work analyzes the impact of user mobility on the execution of cloud-based mobile applications. We propose a Process State Synchronization (PSS)-based execution management to solve the aforementioned problem. We analytically compute a sufficient condition on synchronization interval that ensure reduction in mobile application execution time under PSS in case of disconnection. Similarly, we compute the upper bound on synchronization interval whereby a larger synchronization interval did not result in significant benefits in terms of execution time for the mobile application. The analytical results were confirmed by the sample implementation of PSS with the computed synchronization intervals. Moreover, we also compare the performance of proposed solution with the state-of-the-art solutions. The results show that the PSS-based execution outperforms the other contemporary solutions
Identification of personal traits in adaptive learning environment: Systematic literature review
No full textAn adaptive learning environment provides personalised information to the learner through self-directed study. An adaptive learning environment model can be subdivided into a learner model, domain model, instructional model and adaptive engine. Personal traits comprise part of the components in a learner model and can be identified either explicitly or implicitly in an adaptive learning environment. In such an environment, the e-learning system should adapt to a learner's needs. However, even though academic research on adaptive learning environments has increased, the field lacks a comprehensive literature analysis of learners’ personal traits in these environments. This study conducts a systematic literature review to identify the most commonly used personal traits in modelling the learner and the existing techniques suitable for identifying personal traits in an adaptive learning environment. A total of 140 articles spanning the years 2010–2017 are initially reviewed, from which 78 are selected based on the inclusion and exclusion criteria relevant to this study. This study provides an overview of learners’ personal traits and the techniques used to identify them to provide a basis for improving adaptive learning environments. The findings indicate that most of the previous works used a learning style from the cognition learning domain category to model individual personal traits, while the computer-based detection technique was commonly applied to identify a learner's personal traits in adaptive learning environments. This study reveals the common learner characteristics used to develop learner models and the techniques for implementing such models. The findings of this paper can guide other researchers to recognise various personal traits and the identification technique for further studies, as well as assist developers in the development of the adaptive learning system
Toward improved heat dissipation of the turbulent regime over backward-facing step for the AL2O3-water nanofluids: An experimental approach
No full textExperimental study of nanofluid flow and heat transfer to fully developed turbulent forced convection flow in a uniformly heated tubular horizontal backward-facing step has reported in the present study. To study the forced convective heat transfer coefficient in the turbulent regime, an experimental study is performed at a different weight concentration of Al2O3 nanoparticles. The experiment had conducted for water and Alumina-water nanofluid for the concentration range of 0 to 0.1 wt.% and Reynolds number of 4000 to 16000. The average heat transfer coefficient ratio increases significantly as Reynolds number increasing, increased from 9.6% at Re of 4000 to 26.3% at Re of 16,000 at the constant weight concentration of 0.1%. Alumina-water nanofluid exhibited excellent thermal performance in the tube with a backward-facing step in comparison to distilled water. However, the pressure losses increased with the increase of the Reynolds number and/or the weight concentrations, but the enhancement rates were insignificant