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A centralized multi-objective model predictive control for a biventricular assist device: An in silico evaluation
No full textSpeed regulation of dual left ventricular assist devices (LVADs) as a biventricular assist device (BiVAD) may be complicated by process interactions in a cardiovascular-biventricular assist device (CVS-BiVAD) environment. In this work, a conventional centralized model predictive control (MPC) algorithm that could handle process interactions in a multivariable control problem was modified to cater for the state and time-varying factors of the CVS-BiVAD system as well as to include multiple control objectives. Referred to as the centralized multi-objective model predictive control (CMO-MPC), the scheme's control objectives aim to: a) adapt pump flow rate according to the approximate Frank-Starling (FS) mechanism, b) avoid ventricular suction, and c) avoid vascular congestion. The control performance of the CMO-MPC was benchmarked with two non-centralized control schemes: the constant-speed (CS) control and the standard Frank-Starling like proportional-integral (PI-FS) control under two patient scenarios: exercise and postural change. Simulation results revealed that the CMO-MPC avoided suction and congestion in both patient scenarios as compared to the CS control and the PI-FS control, based on the assumptions made on risks of suction and congestion events. It is therefore proposed that the CMO-MPC should be a safe physiological controller for dual LVADs in the future when reliable pressure and flow sensors become clinically available
Designed antiviral ankyrin – A computational approach to combat HIV-1 via intracellular pathway by targeting the viral capsid of HIV-1
No full textScaffold known as designed ankyrin repeat proteins (DARPins) have been utilized by scientists extensively in protein binding, as they acquire remarkable binding properties. Trimodular ankyrin repeat protein (Ank1D4) is a potential macromolecular and antiviral intracellular inhibitor that aims the N-terminal domain capsid protein (NTDCA) of viral Human Immunodeficiency Virus type-1 (HIV-1) at the virus assembly and budding machinery process. The protein-protein interaction between Ank1D4 and the viral capsid CA alpha helixes H1 and H7 have been studied in depth and point mutation strategy at the S451D4 key residue position was conducted to further improve the binding interaction and efficacy on the wildtype Ank1D4 structure with NTDCA. A computational approach via molecular dynamics (MD) simulation has been fully utilized in this study to simulate both the wildtype and potential novel complexes. Free energy contributions on the modified Ank1D4-NTDCA (H1, H7) complexes were acquired by using vigorous scoring functions of implicit solvent models; Molecular Mechanics/Poisson-Boltzmann surface area (MM-PBSA) and Molecular Mechanics/Generalized Born surface area (MM-GBSA), respectively. The wildtype structure of Ank1D4-NTDCA H7 has been proven to possess better binding stability than the H1 complex. From there, two mutants of H7 complex were generated and the computed ∆Gbind values based on both models have revealed that S45Y-H7 has the lowest binding free energy compared to both S45W-H7 and S45-H7 (Wildtype). The binding strength predictions given by both MM-PBSA and MM-GBSA in the following ranking order for the three systems in terms of the value of ∆Gbind: S45Y-H7 > S45 W-H7 > S45-H7. These findings provide a good basis in directing us a step further to discover better novel treatment modalities to treat millions of HIV-1 patients
Anti-Helicobacter pylori, cytotoxicity and catalytic activity of biosynthesized gold nanoparticles: Multifaceted application
No full textAn unpretentious way to synthesize different sized gold nanoparticles (GNPs) using the dried fruit extract of Tribulus terrestris has been investigated. GNPs were formed due to the reduction of chloroauric acid (HAuCl4) treated with the T. terrestris fruit extract. Formation of GNPs was periodically characterized by UV–Vis spectroscopy. IR spectrum revealed that phytochemicals in the extract played a key role in GNPs synthesis and stability. An anisotropic structure of GNPs with average sizes of 7 nm (GNP7) and 55 nm (GNP55) uses 1 and 2 mM HAuCl4. The biogenic GNP showed a size dependent anti-Helicobacter pylori activity against multidrug resistant H. pylori strains. Furthermore, biogenic GNPs possess an excellent catalytic activity for the reduction of a toxic, p-nitroaniline to p-phenylenediamine as non-toxic by-product. Interestingly, In vitro cell viability of GNP7 and GNP55 on AGS cell lines showed no toxicity at the MIC of H. pylori. The biogenic GNP has excellent biocompatibility, anti-H. pylori and catalytic properties of multifaceted biomedical applications
Efficiency enhancement of dye-sensitized solar cell based gel polymer electrolytes using Poly(vinyl butyral-co-vinyl alcohol-co-vinyl acetate)/tetrapropylammonium iodide
No full textDue to liquid electrolyte limitation in dye sensitized solar cells (DSSCs), GPEs were prepared and optimized. Poly(vinyl butyral-co-vinyl alcohol-co-vinyl acetate), P(VB-co-VA-co-VAc) acted as host polymer and tetrapropylammonium iodide, TPAI as dopant salt. The prepared gel polymer electrolytes (GPEs) with different TPAI salt content were characterized using electrochemical impedance spectroscopy, Fourier transform infrared spectroscopy and X ray diffractogram. An optimum ionic conductivity of 1.93 mS cm−1 was obtained with 40 wt% of TPAI salt added along with the lowest activation energy of 0.064 eV. Temperature dependence ionic conductivity behaviour of GPEs were studied and found that the systems obeyed the Arrhenius behaviour in the temperature range of 303–373 K. The dielectric results studies showed typical behaviour of both ε′ and ε′′ inversely proportional to frequency and directly proportional to temperature. Structural studies of GPEs were performed using XRD and FTIR and confirmed the existence of complexation of P(VB-co-VA-co-VAc) and TPAI salt. GPEs were used to assemble dye sensitized solar cells (DSSCs). The power conversion efficiency of 4.615% achieved with a maximum short circuit current density (Jsc) of 13.585 mA cm−2, open circuit voltage (Voc) of 0.678 V and fill factor of 50.1% at 40 wt% TPAI salt under A.M 1.5 (100 mW cm−2) illumination
A bibliometric analysis of m-learning from topic inception to 2015
No full textMobile learning is a promising and widely adopted mode of education nowadays. However, to the best of our knowledge, there have been no studies that have investigated publications on the use of mobile learning in the Thomson Reuters Web of Science (WoS) through bibliometric analysis. This study aims to provide readers with statistical information to obtain a deep understanding of this domain. The results show that 3087 mobile learning publications have been published since 1982. As a result, the study has compared and determined the possible ways for researchers and authors to improve the citation rate of their publications on m- learning and to gain a deeper understanding of the field of mobile learning by studying the number of publications and country, the number of authors, the keywords, the number of references, the number of pages, the journal, the authors' publications, and the number of citations. Additionally, other bibliometric results are discussed
Molecular phylogeography and genetic diversity of Angiostrongylus cantonensis and A. malaysiensis (Nematoda: Angiostrongylidae) based on 66-kDa protein gene
No full textAngiostrongylus cantonensis is the main causative agent of human angiostrongyliasis. A sibling species, A. malaysiensis has not been unequivocally incriminated to be involved in human infections. To date, there is only a single report on the application of the partial 66-kDa protein gene sequence for molecular differentiation and phylogeny of Angiostrongylus species. Nucleotide sequences of the 66-kDa protein gene of A. cantonensis and A. malaysiensis from Thailand, as well as those of the laboratory strains of A. cantonensis from Thailand and Hawaii, A. cantonensis from Japan and China, A. malaysiensis from Malaysia, and A. costaricensis from Costa Rica, were used for the reconstruction of phylogenetic tree by the maximum likelihood (ML) method and the haplotypes by the median joining (MJ) network. The ML phylogenetic tree contained two major clades with a full support bootstrap value – (1) A. cantonensis and A. malaysiensis, and (2) A. costaricensis. A. costaricensis was basal to A. cantonensis and A. malaysiensis. The genetic distance between A. cantonensis and A. malaysiensis ranged from p =.82% to p = 3.27%, that between A. cantonensis and A. costaricensis from p = 4.90% to p = 5.31%, and that between A. malaysiensis and A. costaricensis was p = 4.49% to p = 5.71%. Both A. cantonensis and A. malaysiensis possess high 66-kDa haplotype diversity. There was no clear separation of the conspecific taxa of A. cantonensis and A. malaysiensis from different geographical regions. A more intensive and extensive sampling with larger sample size may reveal greater haplotype diversity and a better resolved phylogeographical structure of A. cantonensis and A. malaysiensis
Panda resonator structure to generate four-wave mixing by nonlinear effect
No full textFinite-difference time domain (FDTD) simulation has been used for modeling of nonlinear optical interaction in a modified microring resonator as Panda structure. By proposing the Panda structure which has been modeled using both silicon and material (Chi2) with nonlinear effect, generation of four-wave mixing is feasible. Due to the nonlinear interaction between the two input waves as pump and signal within the microring resonators the results show the generation of three picks including the pump, signal and converted wave. In the case, if the silicon has been utilized as the core waveguide, the resonance interferences occur, where the high Qfactor of the resonance frequencies was obtained as 3.87 × 103 in the drop port outputs. Compared to silicon material, the nonlinear material shows a better power transferring performances. In the results showing the four-wave mixing, the converted wave has a lower power than the signal and pump
Fabrication and characterization of porous scaffolds for bone replacements using gum tragacanth
No full textThe practice of bone implants is the standard procedure for the treatment of skeletal fissures, or to substitute and re-establish lost bone. A perfect scaffold ought to be made of biomaterials that duplicate the structure and properties of natural bone. However, the production of living tissue constructs that are architecturally, functionally and mechanically comparable to natural bone is the major challenge in the treatment and regeneration of bone tissue in orthopaedics and in dentistry. In this work, we have employed a polymeric replication method to fabricate hydroxyapatite (HAP) scaffolds using gum tragacanth (GT) as a natural binder. GT is a natural gum collected from the dried sap of several species of Middle Eastern legumes of the genus Astragalus, possessing antibacterial and wound healing properties. The synthesized porous HAP scaffolds were analyzed structurally and characterized for their phase purity and mechanical properties. The biocompatibility of the porous HAP scaffold was confirmed by seeding the scaffold with Vero cells, and its bioactivity assessed by immersing the scaffold in simulated body fluid (SBF). Our characterization data showed that the biocompatible porous HAP scaffolds were composed of highly interconnecting pores with compressive strength ranging from 0.036 MPa to 2.954 MPa, comparable to that of spongy bone. These can be prepared in a controlled manner by using an appropriate binder concentration and sintering temperature. These HAP scaffolds have properties consistent with normal bone and should be further developed for potential application in bone implants
Forecasting hydrological parameters for reservoir system utilizing artificial intelligent models and exploring their influence on operation performance
No full textObtaining successful operation rules for dam and reservoir systems is crucial for improving water management to meet the increase in agricultural, domestic and industrial activities. Several research efforts have been developed to generate optimal operation rules for dam and reservoir systems utilizing different optimization algorithms. The main purpose of an operation rule is to minimize the gap between water supply and water demand patterns. To examine the optimized model performance, the simulation of a dam and reservoir system is usually carried out for a particular period utilizing the generated operation rule. During the simulation procedure, although reservoir inflow and evaporation are stochastic variables that are required to be forecasted during simulation, they are considered deterministic variables. This study attempts to integrate a forecasting model for reservoir inflow and evaporation with the operation rules generated from optimization models during the simulation procedure. The present study employs several optimization models to generate an optimal operation rule and two different forecasting models for reservoir inflow and reservoir evaporation. The three different optimization algorithms used in this study are the genetic algorithm (GA), particle swarm optimization (PSO) algorithm and shark machine learning algorithm (SMLA). Two different forecasting models have been developed for reservoir inflow and evaporation using the radial basis function neural network (RBF-NN) and support vector regression (SVR). It is necessary to analyze the proposed simulation procedure for examining the operation rule to comprehend the analysis under different optimal operation rules and levels of accuracy for both hydrological variables. The suggested models have been applied to generate optimal operation policies and reservoir inflow and evaporation forecasts for the Timah Tasoh dam (TTD) located in Malaysia. The results show that the major findings regarding the model performance during the simulation period indicate the necessity to pay attention to evaluating the optimized model performance by considering the results of the forecasting model for both the hydrological variables of reservoir inflow and reservoir evaporation rather than the deterministic values
Effects of various alkali metal cations on the synthesis, crystallization and catalytic properties of NKX-2 aluminophosphites
No full textAlkali metal-containing NKX-2 (M-NKX-2) aluminophosphite crystals were hydrothermally synthesized in the Al2O3–P2O5–M2O–H2O system for the first time using various alkali metal hydroxides (MOH: M = Li, Na, K, Cs). The results showed that NKX-2 crystalline phase could be obtained within several hours without using harmful organic amine structure-directing agent. In addition, the alkali metal hydroxides played an important role in controlling the crystallization rate and the morphology of M-NKX-2 particles in aqueous medium. The resulting M-NKX-2 solids possessed basicity which was catalytically active in base-catalyzed cyanoethylation reaction of methanol