ADSORPTION OF MERCURIC ION FROM AQUEOUS SOLUTIONS USING MODIFIED FLY ASH

In this study, fly ash was treated with NaOH solution (FAN) before modifying with (3-mercaptopropyl) triethoxysilane - MPTMS (FAMPS). By using FTIR, FESEM, XRD, EDX, and BET techniques, the change in structure, composition and morphology of FAN and FAMPS was evaluated. The FTIR spectra of FAN and FAMPS showed that there is no chemical reaction between the MPTMS and FAN. After modification, the FAMPS has a rough surface with composition difference from the FAN. Mercuric ion adsorption behavior as well as adsorptionisotherm models (Langmuir and Freundlich) of the FAN and FAMPS were also investigated and discussed. Thanks to FAN modification, the mercuric ion removal percent of the FAMPS was higher than that of the FAN. Owing to the adsorption data, Freundlich isotherm modelwas fitted for the mercuric ion adsorption process

On the Way to a Theory for Network Architectures

Abstract. The design of the future Internet is facing real challenges on network architecture. Attempts to resolve the issues related to naming/addressing, middle boxes, QoS-Security-Mobility interactions, cross-layer and inter-domain usually lead to endless debates. This is because the structure of the Internet has become too complex and has evolved with new functions added which are not always compatible with the existing functions. In order to analyze the architecture of the Internet in a strict manner, it is necessary to understand in depth the composition of functionalities within a protocol or between protocols. This paper presents a study on the composition of network functionalities and highlights future directions towards a theory for network architectures which includes the principles that network architectures should follow to ensure the normal operation of the member functions, detect all possible conflicts between them as well as figure out impossibilities

Limitations of OpenFlow Topology Discovery Protocol

OpenFlow Discovery Protocol (OFDP) is the de-facto protocol used by OpenFlow controllers to discover the underlying topology. In this paper, we show that OFDP has some serious security, efficiency and functionality limitations that make it non suitable for production deployments. Instead, we briefly introduce sOFTD, a new discovery protocol with a built-in security characteristics and which is more efficient than traditional OFDP.Comment: The peer reviewed version can be found here (to be published soon

Using fly ash treated by NaOH and H2SO4 solutions for Hg2+ and Cd2+ ion adsorption.

This paper presents the results of adsorption ability of heavy metal ions (Hg2+ and Cd2+) by fly ash (FA) before and after treatment using NaOH and H2SO4 solutions.  Original- and treated FA were characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and Scanning Electron Microscope (SEM). Specific surface area of FA before and after treatment was calculated by Brunauer – Emmett – Teller (BET) isotherm equation. The obtained results indicated that the morphology and specific surface area of FA changed clearly after treatment by acid or alkaline solutions. Adsorption capacity the Hg2+ and Cd2+ ion by FA was determined from data of UV-Vis spectra. After treatment, the adsorption capacity of ions by FA increased remarkably in comparison with non-treated FA. The FA treated by NaOH solution has the adsorption capacity higher than FA treated by H2SO4 solution. The maximum adsorption capacity of the FA treated by NaOH solution for Cd2+ and Hg2+ ions at room temperature is 28.97 and 14.60 mg/g, respectively. The equilibrium adsorption data were described by the Langmuir and Freundlich isotherm models. The results showed that equilibrium data were fitted well to the Langmuir isotherm. Keywords. Fly ash, treatment, adsorption capacity, heavy metal, Langmuir isotherm

Workload doesn’t mean exhaustion: Antecedents of teacher burnout

Workload has consistently been found to be a predictor of burnout in teachers.  However, while academia considers workload a psychological concept, the public tends to simplify workload as the number of tasks assigned. This study seeks to provide further evidence of the psychological nature of workload by examining if workload understood in terms of quantity of work had any effect on teacher burnout and whether this relationship was moderated by psychological processes such as self-efficacy and mediated by stress. 117 primary and high school teachers holding at least two roles at school participated in the study. Teacher burnout was measured using MBI-ES, self-efficacy was measured by OSTES and stress and workload were measured by single-item questions. Results showed that workload (i.e., the number of roles assigned) did not have a main effect on burnout. Perceived stress and self-efficacy had direct effects on teacher burnout: stress increased burnout while self-efficacy reduced burnout. Self-efficacy had a significant moderation effect on workload-burnout interaction. Workload increased burnout only in teachers with low self-efficacy  while stress did not moderate the workload-burnout relationship. These findings support the psychological nature of the relationship between workload and burnout among teachers. They also point out the importance of enhancing teacher stress management and self-efficacy in protecting them from burnout

COUNTERFEITS AND THEIR COSTS

Counterfeiting is increasing and becoming a complicated issue across different countries in the world and Vietnam is not exceptional, so the policy makers and managers always try to find ways to face with the counterfeiting and reduce counterfeit products in the market. This paper attempts to investigate determinants that impact on consumers’ attitude toward non-deceptive counterfeit products and behavioral intention to purchase them. Using a data set collected from a sample of 176 consumers we found that social cost has an impact on consumers’ attitude and purchase intentiontoward counterfeit products. Moreover, the result indicates that intention to buy counterfeit products is influenced by consumers’ attitude toward these products. These findings suggest that companies should rely on the social cost as the main component of marketing communication messages to discourage consumption of fake products by implying the seriously harmful consequences of these goods to society and economy

Genetic characteristics of Panax vietnamensis Ha & Grushv. populations based on ssr

The results of genetic analysis of two Panax vietnamensis populations, collected in Tac-ngo ginseng garden, Tra Linh commune, Quang Nam Province and Mang ri ginseng garden, Kon Tum Province, showed that the population of ngoc linh ginseng in Quang Nam has higher alen frequency compared to the Ngoc Linh ginseng population in Kon Tum (AR = 2.27 AR = 2.05). The population of ngoc linh ginseng in Quang Nam has the expected heterozygous frequency (He) higher than the expected heterozygous frequency of the ginseng population in Kon Tum (0.42 0.4). The observed heterozygous frequency (Ho) of the ngoc linh population in Quang Nam was also higher than the observed heterozygous frequency compared to the ngoc linh ginseng population in Kon Tum (0.49 0.43). These results demonstrated that both populations of ngoc linh ginseng in Quang Nam and Kon Tum are maintaining high heterozygous frequencies; self-pollination has not affected to the genetic structure of these both populations yet. However, the population of ngoc linh ginseng in Quang Nam showed a higher level of diversity and heterozygous frequency than the ngoc linh ginseng population in Kon Tum.

PREPARATION AND FTIR STUDIES OF PMMA/PVC POLYMER BLENDS, PVC-g-PMMA GRAFT COPOLYMERS AND EVALUATING GRAFT CONTENT

This study presents the qualitative and quantitative analyses of Fourier Transform Infrared (FTIR) spectra of poly(methyl methacrylate)/poly(vinyl chloride) blends (PMMA/PVC), as well as PVC-g-PMMA graft copolymers. Graft copolymerizations of methyl mathacrylate (MMA) onto PVC macromolecules were carried out mixture of cyclohexanone/N,N-dimethylformamide as solvents, dibenzoyl peroxide as initiator and nitrogen medium. FTIR spectra of PMMA/PVC blends showed that there were molecular interactions between C=O groups of PMMA and C-Cl groups of PVC. Assignments of infrared absorption bands for specific groups of PMMA/PVC blends have been contributed. Using regression method, linear calibration curve between PMMA mole content and peak areas of C=O groups in FTIR spectra of the blends has been found when C=O peak areas were multiplied by an appropriate factor. PMMA grafted content and total PMMA formed content in PVC-g-PMMA graft copolymers have been evaluated. The results showed that grafted PMMA content was increased since PVC was initiatly dechlorinated by NaOH solution. The grafted PMMA content and total formed PMMA content were 5.05 wt.% and 11.25 wt.% respectively when MMA monomers were grafted onto neat PVC and modified PVC molecules

Electrodeposition of HAp coatings on Ti6Al4V alloy and its electrochemical behavior in simulated body fluid solution

Hydroxyapatite (HAp) coatings were prepared on Ti6Al4V substrate by electrodeposition method from electrolyte solution containing Ca(NO3)2, NH4H2PO4 and NaNO3. The results show that the HAp coatings were single phase crystals of HAp. Scanning electron microscope (SEM) images present that HAp/Ti6Al4V have flake shapes which arrange to form like-coral agglomerates. In vitro test of the Ti6Al4V and HAp/Ti6Al4V in simulated body fluid (SBF) solution was investigated with different immersion times. pH of SBF solution decreased and the mass of materials increased. SEM images prove the formation of apatite on the surface of Ti6Al4V and HAp/Ti6Al4V. The corrosion current density during immersion time of substrate is always higher than the one of HAp/Ti6Al4V because the deposited HAp can protect well for the substrate