Efficient preconcentration and determination of traces of aluminum ion using silica-bonded glycerol sorbent

A solid-phase extraction system was proposed for the determination of aluminum after preconcentration with glycerol-bonded silica gel. The method is rapid and efficient for the enrichment of aluminum ions at trace levels. Optimal sorption conditions were found for sorption and desorption of aluminum ions. The effects of diverse ions on the sorption and recovery of aluminum have been studied and it was shown that the selectivity of the sorption process was very good. A very satisfactory preconcentration factor of 500 was achieved by this method. The lowest concentration of aluminum ions for quantitative recovery was 2ngml(-1). The capacity of sorbent was 400microg per gram of sorbent. The method showed good reproducibility (R.S.D.=2.2% for n=7) and was applied to the determination of aluminum in mineral water, hair and green tea samples.     

An audit on hospital management of bronchial asthma

Medical audit is a new concept in developing countries like Pakistan. We carried out this retrospective study on bronchial asthma. The purpose was to see if care given to patient with asthma meets the accepted international standard or not. During this audit several deficiencies were found. Documentation in notes about signs indicating severity of asthma was very poor. Peak flow recording in the notes was also very deficient. There was no documentation in notes whether inhalers technique of the patients has been checked or not. This audit shows that care given to asthma patients is far from satisfactory and we clearly need to improve in order to reach the accepted international standards.     

Equilibrium, kinetic and thermodynamic studies of mercury adsorption on almond shell

The application of almond shell as a low cost natural adsorbent to remove Hg(2+) from aqueous solution was investigated. Batch experiments were carried out to evaluate the adsorption capacity of the material. The chemical and physical parameters such as pH, sorbent amount, initial ion concentration, and contact time were optimized for the maximum uptake of mercury onto the solid surface. Adsorption isotherms were expressed by Langmuir and Freundlich adsorption models, and the experimental data were found to fit the Langmuir model rather than the Freundlich. The maximum adsorption capacity obtained from the Langmuir isotherm was 135.13 mg/g. A kinetic study was carried out with pseudo-first-order and pseudo-second-order reaction equations and it was found that the Hg(2+) uptake process followed the pseudo-second-order rate expression. The thermodynamic values, ΔG(0), ΔH(0) and ΔS(0), indicated that adsorption was an endothermic and spontaneous process. The potential of this material for mercury elimination was demonstrated by efficient Hg(2+) removal from a synthetic effluent.     

An efficient genetic algorithm for solving the quay crane scheduling problem

This paper addresses the quay crane scheduling problem (QCSP), which has been shown to be NP-complete. For this reason, a number of studies have proposed the use of genetic algorithm (GA) as the means to obtain the solution in reasonable time. This study extends the research in this area by utilizing the GA that is available in the latest version of Global Optimization Toolbox in MATLAB 7.13 to facilitate development. It aims to improve the efficiency of the GA search by (1) using an initial solution based on the S-LOAD rule developed by Sammarra, Cordeau, Laporte, and Monaco (2007), (2) using a new approach for defining the chromosomes (i.e., solution representation) to reduce the number of decision variables, and (3) using new procedures for calculating tighter lower and upper bounds for the decision variables. The effectiveness of the developed GA is tested using several benchmark instances proposed by Meisel and Bierwirth (2011). Compared to the current best-known solutions, experimental results show that the proposed GA is capable of finding the optimal or near-optimal solution in significantly shorter time for larger problems.     

Doping Strategy for Efficient and Stable Triple Cation Hybrid Perovskite Solar Cells and Module Based on Poly(3‐hexylthiophene) Hole Transport Layer

As the hole transport layer (HTL) for perovskite solar cells (PSCs), poly(3‐hexylthiophene) (P3HT) has been attracting great interest due to its low‐cost, thermal stability, oxygen impermeability, and strong hydrophobicity. In this work, a new doping strategy is developed for P3HT as the HTL in triple‐cation/double‐halide ((FA_1?x?yMA_xCs_y)Pb(I_1?xBr_x)₃) mesoscopic PSCs. Photovoltaic performance and stability of solar cells show remarkable enhancement using a composition of three dopants Li‐TFSI, TBP, and Co(III)‐TFSI reaching power conversion efficiencies of 19.25% on 0.1 cm² active area, 16.29% on 1 cm² active area, and 13.3% on a 43 cm² active area module without using any additional absorber layer or any interlayer at the PSK/P3HT interface. The results illustrate the positive effect of a cobalt dopant on the band structure of perovskite/P3HT interfaces leading to improved hole extraction and a decrease of trap‐assisted recombination. Non‐encapsulated large area devices show promising air stability through keeping more than 80% of initial efficiency after 1500 h in atmospheric conditions (relative humidity ≈ 60%, r.t.), whereas encapsulated devices show more than >500 h at 85 °C thermal stability (>80%) and 100 h stability against continuous light soaking (>90%). The boosted efficiency and the improved stability make P3HT a good candidate for low‐cost large‐scale PSCs.     

Synthesizing structural and behavioral control for reconfigurations in component-based systems

Correctness of the behavior of an adaptive system during dynamic adaptation is an important challenge to realize correct adaptive systems. Dynamic adaptation refers to changes to both the functionality of the computational entities that comprise a composite system, as well as the structure of their interconnections, in response to variations in the environment, e.g., the load of requests on a server system. In this research, we view the problem of correct structural adaptation as a supervisory control problem and synthesize a reconfiguration controller that guides the behavior of a system during adaptation. The reconfiguration controller observes the system behavior during an adaptation and controls the system behavior by allowing/disallowing actions in a way to ensure that a given property is satisfied and a deadlock is avoided. The system during adaptation is modeled using a graph transition system and properties to be enforced are specified using a graph automaton. We adapt a classical theory of supervisory control for synthesizing a controller for controlling the behavior of a system modeled using graph transition systems. This theory is used to synthesize a controller that can impose both behavioral and structural constraints on the system during an adaptation. We apply a tool that we have implemented to support our approach on a case study involving https servers.     

Proxy signatures and buyer–seller watermarking protocols for the protection of multimedia content

Watermarking techniques are developed to deal with multimedia distribution, authentication and copyright protection. It is usually the seller who embeds a watermark in multimedia content to identify the buyer. The embedded watermark can then be used to trace the traitors identity if unauthorized copies are found. However, repudiation and framing issues might arise in this approach. To solve these problems, buyer–seller watermarking protocols have been proposed based on watermarking in the encrypted domain. Such watermarks combine encryption, digital watermarking, and fingerprinting to preserve digital rights of both the buyer and the seller. Unfortunately, most existing watermarking techniques do not provide convincing proofs to ensure that they achieve the claimed level of security and informal proofs abound in the literature. In this paper, we propose a buyer–seller watermarking protocol based on proxy signatures and homomorphic encryption. Formal proofs are provided to show that in the proposed protocol, watermarks are generated such that the seller is unable to fabricate piracy, but he can trace copyright violators. The protocol further protects anonymity of the buyer until he is adjudicated to be guilty. Moreover, we solve the conspiracy problem without imposing any unrealistic assumptions about thrust-worthiness of the parties involved.     

Deep extractive desulfurization of oil over 12-molibdophosphoric acid encapsulated in metal-organic frameworks

A desulfurization process for model oil and real oil was investigated based on the chemical oxidation of mixed sulfur containing compounds in the presence of nitrogen compounds (indole and quinoline) using hydrogen peroxide as oxidizing agent and dodecamolibdophosphoric acid (H₃PMo₁₂O₄₀) encapsulated in a kind of metal-organic framework (HKUST-1) as PMo@HKUST-1. The effect of isopropanol, ethanol and acetonitrile as extractive solvent and 1-ring (toluene, xylene and mesitylene) and 2-ring (naphthalene) aromatic hydrocarbons in desulfurization of model oil was studied. The desulfurization of sulfur-containing compounds was accelerated in the presence of aromatic hydrocarbons. In fact, a higher desulfurization efficiency of the heterogeneous catalyst could be achieved with system containing a polar solvent in contact with an aromatic hydrocarbon. Quinoline had no effect on oxidative desulfurization (ODS) reaction, whereas indole had a slightly negative effect. Presence of aromatic compounds had slightly positive effect on ODS reaction.     

Application of Taguchi approach in describing the mechanical properties and thermal decomposition behavior of poly(vinyl chloride)/clay nanocomposites: Highlighting the Role of organic modifier

Mechanical and thermal properties of poly(vinyl chloride) (PVC)/nanoclay (NC) composites prepared via melt‐blending in a single‐screw extruder were investigated. The effects of NC type, NC content, and K‐value of PVC were evaluated by using L9 orthogonal array of the Taguchi approach. The most influential variables and significance of interactive effects were examined for the highest values of Young's modulus and hardness. Scanning electron micrographs and X‐ray diffraction patterns revealed the formation of exfoliated/intercalated structures. Although the K‐value has a minor individual effect on mechanical characteristics, the interaction of the K‐value with NC type and NC content is significant. The composites were also characterized and tested by using analysis by thermal gravimetry, differential thermogravimetry, and differential scanning calorimetry methods. The results of the thermal studies indicated that decomposition of the organic modifier of NCs has a catalytic effect on the dehydrochlorination of PVC. This finding justifies the rather low mechanical properties of PVC/organoclay nanocomposites. Fourier‐transform infrared spectra of the samples were indicative of accelerated degradation reactions, which provided support for above observations. J. VINYL ADDIT. TECHNOL., 22:182–190, 2016. © 2014 Society of Plastics Engineers