Forecasting nonlinear time series with a hybrid methodology

In recent years, artificial neural networks (ANNs) have been used for forecasting in time series in the literature. Although it is possible to model both linear and nonlinear structures in time series by using ANNs, they are not able to handle both structures equally well. Therefore, the hybrid methodology combining ARIMA and ANN models have been used in the literature. In this study, a new hybrid approach combining Elman’s Recurrent Neural Networks (ERNN) and ARIMA models is proposed. The proposed hybrid approach is applied to Canadian Lynx data and it is found that the proposed approach has the best forecasting accuracy.     

Starch-based gel electrolyte thin films derived from native sago (Metroxylon sagu) starch

Starch-based gel electrolyte (SbGE) thin films were prepared by mixing native sago starch with different amounts of glycerol, and subsequently doped with various types of ionic salts. SbGE thin films showed substantially enhanced mechanical properties and ionic conductivity through incorporating optimal composition of native sago starch, glycerol, and ionic salts. A maximum room temperature ionic conductivity of the order of 10^?3 S cm^?1 was achieved for optimized SbGE thin film consisting of 80 wt% of native sago starch and 20 wt% of glycerol, and doped with 8 wt% of LiCl. SbGE thin films were characterized by Fourier transformed infrared spectrometry, scanning electron microscopy, and electrochemical impedance spectroscopy. Due to their favorable mechanical properties, high ionic conductivity at room temperature, ease of preparation, environmentally benign, and cheap, SbGE thin films show high potential utility as gel electrolyte materials for the fabrication of solid-state electrochemical devices.     

Exact solution of the time-dependent harmonic plus an inverse harmonic potential with a time-dependent electromagnetic field

In this paper, the problem of the charged harmonic plus an inverse harmonic oscillator with time-dependent mass and frequency in a time-dependent electromagnetic field is investigated. It is reduced to the problem of the inverse harmonic oscillator with time-independent parameters and the exact wave function is obtained.     

Improvements on Generalized Hamming Weights of Some Trace Codes

We obtain improved bounds for the generalized Hamming weights of some trace codes which include a large class of cyclic codes over any finite field. In particular, we improve the corresponding bounds of Stichtenoth and Voss [8] using various methods altogether.     

Buckling and vibration of non-ideal simply supported rectangular isotropic plates

Buckling and vibration of a rectangular isotropic plate which has non-ideal simply supported boundary conditions along one of its edges are investigated. It is assumed that one of the edges of the plate allows a small non-zero deflection and a small non-zero moment. Externally applied in-plane loads are considered to be parallel and perpendicular to the edge where non-ideal boundary conditions are present in the buckling problem. Analytical solutions of the buckling and vibration problems are obtained by using the Linshtead–Poincare perturbation technique. Improved buckling loads and natural frequencies are determined for various values of the aspect ratio of the plate.     

Synthesis and bioactivities of 1-(4-hydroxyphenyl)-2-((heteroaryl)thio)ethanones as carbonic anhydrase I,II and acetylcholinesterase inhibitors

The discovery of enzyme targeting inhibitors is a popular area of drug research. Biological activities of the compounds bearing phenol and heteroaryl groups make them popular groups in drug design targeting important enzymes such as acetylcholinesterase (AChE, E.C.3.1.1.7) and carbonic anhydrases (CAs, EC 4.2.1.1). 1-(4-hydroxyphenyl)- 2-((aryl)thio)ethanones as possible AChE and CAs inhibitors were synthesized, and their chemical structures were confirmed by IR, ¹H NMR, ¹³C NMR, and HRMS. The compounds 2 and 4 were found potent AChE inhibitors with the Ki values of 22.13 ±1.96 nM and 23.71 ±2.95 nM, respectively, while the compounds 2 (Ki = 8.61 ±0.90 nM, on hCA I) and 1 (Ki = 8.76 ±0.84 nM, on hCA II) had considerable CAs inhibitory potency. The lead compounds may help the scientists for the rational designing of an innovative class of drug candidates targeting enzyme-based diseases.     

Development of implantable hydroxypropyl-β-cyclodextrin coated polycaprolactone nanoparticles for the controlled delivery of docetaxel to solid tumors

Treatment of cancer is one of the most challenging problems and conventional therapies are inadequate for targeted, effective and safe therapy. Development of nanoparticle-based drug delivery systems emerge as promising carriers in this field to ensure delivery of anticancer drug to tumor site. The aim of this study was to design hydroxypropyl-β-cyclodextrin (CD) coated nanoparticles using poly(ε-caprolactone) (PCL) and its derivative poly(ethylene glycol)-block-poly(ε-caprolactone) (mePEG-PCL) to be applied as implants to tumor site following surgical operation in cancer patients. CD coated PCL and mePEG-PCL nanospheres were developed to encapsulate poorly soluble chemotherapeutic agent docetaxel (DOC) to improve solubility of drug and to enhance cellular penetration with longer residence time and higher local drug concentration. Nanospheres were prepared according to the nanoprecipitation method and coated with hydroxypropyl-β-cyclodextrin (Cavasol^® W7HP). Cyclodextrin coating was performed for higher drug encapsulation and controlled but complete drug release from nanoparticles. Nanoparticle diameters varied between 60 and 136 nm depending on polymer used for preparation and coating. All nanoparticles have negative surface charge and zeta potential values varied between ?22 and ?37 mV. Encapsulation efficiency of formulations were found to be between 46 and 73 % and CD coated nanoparticles have significantly higher entrapment efficiency. Drug release profiles of nanoparticles were similar to each other and all formulations released encapsulated drug in approximately 12 h. Especially, CD-PCL nanoparticles were found to have highest entrapment efficiency and anticancer efficacy against MCF-7 human breast adenocarcinoma cell lines. Our study proved that polycaprolactone and its PEGylated derivatives can be suitable for development of implantable nanoparticles as a potential drug delivery system of DOC for cancer treatment and a good candidate for further in vivo studies.     

Determination and evaluation of natural radioactivity and heavy metal levels in the aquatic environment of trans-boundary rivers: Maritza,Tundja and Arda

The main problem in the trans-boundary river system is that heavy metal and radioactive pollution can cause long-term effects on ecosystems. Therefore the natural radioactivity and heavy metal levels in the Maritza, Tundja and Arda Rivers, common for Bulgaria and Turkey, were determined for 3 years period (2007–2010). Gross alpha, gross beta and total radium isotopes activities, uranium and heavy metal concentrations of the surface water of the rivers were investigated and also terrestrial gamma and gamma dose rate were measured. The results were compared with reported data from other countries of the world and the recommended international standards. The results gathered in this study may provide background data on the natural radioactive and heavy metal levels of these trans-boundary rivers.     

Neodymium and samarium recovery by magnetic nano-hydroxyapatite

The removal and recovery of lanthanides has become important because of their wide applications in industry and also in environmental protection. The necessity for these elements requires the selective and effective separation technique. In this study, batch adsorption method as a green technology has been investigated for removal and recovery of Nd and Sm using magnetic nano-hydroxyapatite adsorbent (MNHA). According to results, the maximum adsorption capacities of Nd and Sm were calculated as 323 and 370 mg/g at optimum pH 5.5, respectively. Different types of adsorption isotherms and kinetic models were used to describe the Nd and Sm adsorption behavior, and the experimental results fitted Langmuir model and the pseudo-second-order kinetic models well. The adsorption of Nd and Sm was found as endothermic and spontaneous process with respect to obtained thermodynamic parameters. Recovery of adsorbed lanthanides and reusability of adsorbent was tested. Possible adsorption mechanisms were also discussed. The proposed adsorbent, MNHA has good adsorption ability and high sorption capacity for Nd and Sm with a chemisorption mechanism.