Superabsorbent hydrogel based on modified polysaccharide for removal of Pb2+ and Cu2+ from water with excellent performance

This contribution describes the absorption percentage of Pb²⁺ and Cu²⁺ from water by a superabsorbent hydrogel matrix (SH) made from an anionic polysaccharide copolymerized with acrylic acid (AAc) and acrylamide (AAm). Metal‐absorption tests, upon sequential pH variation, indicated that the SH has pH‐sensitivity for the absorption of both metals from solution, attributed to the functional ionic groups (? COOH) present in the AAc and arabic gum (AG) segments. At the pH 5.0, the SH exhibited good absorption capacity: 73.10% for Pb²⁺, 81.99% for Cu²⁺ in water and 63.64% for Pb²⁺, and 76.67% for Cu²⁺ in saline water with 0.1 mol kg^?1 ionic strength. A replicated 2² full factorial design with a central point was built to evaluate the maximum absorption capacity of the metals into the SH. It was found that both the interaction and main effects of the pH and the initial concentration of metal solution on absorption percentage of the metals were statistically significant. Surface response plots indicated that the absorption capacity of both metals into the SH may be appreciably improved by using the solutions with lower initial concentration of metal and with higher pH values. Metal‐absorption results demonstrated that the SH is a convenient material for absorption of Pb²⁺ and Cu²⁺ from pure aqueous and saline aqueous environments. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Conjugated dienes and trienes from methyl oleate and methyl linoleate

Methyl oleate and methyl linoleate were converted to conjugated dienes and trienes, respectively, by selecting and modifying the conventional procedures usually applied to the generation and characterization of fatty hydroperoxides. Conditions have been studied in the laboratory for: (a) the optimum production of hydroperoxides with a minimum of by-products, (b) the effective separation and concentration of the resulting hydroperoxide, (c) the economic reduction of the hydroperoxide mixture, (d) simple dehydration of the reduced product, and, (e) recovery of the resulting polyene-rich material. If the processing sequence is halted after the reduction step, the resulting product,is a mixture of allylic hydroxy monoene or diene methyl esters. Our investigations have been extended to include studies on the methyl esters of commercial oleic acid and the mixture of methyl esters resulting from alcoholysis of lard oil. Products containing 20–25% conjugated diene and lesser proportions of conjugated triene were obtained. Presented at the AOCS Meeting, Houston, April 1965. E. Utiliz, Res. Dev. Div., ARS, USDA.     

The effect of nanoclays on the nucleation,crystallization, and melting mechanisms of isotactic polypropylene

The influence of organomodified nanoclay (montmorillonite) on the crystallization and melting mechanisms of isotactic polypropylene (iPP) was studied. Films of both neat polymer and clay nanocomposites were prepared after molecular weight optimization through melt extrusion. Products exhibited the tactoidlike morphology since no compatibilizers were used. The effect of introduction of nanoclay within the polymer was studied through isothermal crystallization and linear heating. The results indicated that low nanoclay concentrations induce the formation of the β‐crystalline structure, its formation being inhibited with high nanoclay contents. Dynamic nonisothermal bulk crystallization experiments indicated that nanoclays act as nucleating agents of iPP. Isothermal, bulk crystallization studies indicated that the crystallization process (induction time and crystallization kinetics) is proportionally accelerated by the nanoclay presence. There was also an accelerated formation of secondary crystallization when nanoclays were present in high concentrations. POLYM. ENG. SCI., 47:1889–1897, 2007. © 2007 Society of Plastics Engineers     

Microstructure and creep behavior in AE42 magnesium die-casting alloy

The micro structural analysis of die-cast AE42 reveals a correlation between micro structure and creep strength. A lamellar-phase Al₁₁RE₃, which dominates the interdendritic microstructure of the alloy, partly decomposes above 150‡C into Al₂RE and Al (forming Mg₁₇Al₁₂). The increased solubility of aluminum in magnesium at higher temperatures may also promote the decomposition of Al₁₁RE₃. The creep strength decreases sharply with these phase changes. A mechanism for the decrease in creep strength of AE42 is proposed whereby the reduced presence of lamellar Al1₁₁RE₃ and/or the presence of Mg₁₇Al₁₂ contribute to the observed poor creep strength at higher temperatures.     

Linear Programming Formulation for Strategic Dynamic Traffic Assignment

This work introduces a novel formulation of system optimal dynamic traffic assignment that captures strategic route choice in users under demand uncertainty. We define strategic route choice to be that users choose a path prior to knowing the true travel demand which will be experienced (therefore users consider the full set of possible demand scenarios). The problem is formulated based on previous work by Ziliaskopoulos (Transp Sci 34(1):37–49, 2000). The resulting novel formulation requires substantial enhancement to account for path-based flows and scenario-based stochastic demands. Further, a numerical demonstration is presented on a network with different demand loading profiles. Finally, model complexity, implications on scalability and future research directions are discussed.     

Subjective measurement of cosmetic defects using a Computational Intelligence approach

This paper presents a Computational Intelligence scheme to deal with subjective human inspection tasks in the industry that are subjective measurements. The scheme is used to solve two cosmetic subjective measurements tasks, classification of cosmetic defects and detection of non-uniform color regions in a translucent film. The first problem is solved with two approaches supervised and unsupervised Artificial Neural Networks. Both techniques yield the same performance, 92.35% of correct classification. Considering that a human inspector has a performance between 85% and 90%, the performance achieved is acceptable. The second problem is faced with a hybrid system based on fuzzy clustering and a Self-Organizing Map. The hybrid approach involves management of uncertainty through fuzzy theory and unsupervised training supported by the SOM. The proposed system is able to find non-uniform color regions with better resolution than a human inspector. The system also showed to be more sensitive than a simple fuzzy clustering approach.     

Mobile code, distributed computing, and agents

The author briefly describes some of the Jini networking system's features and attempts to show how this system's assumptions differ from those used to construct other distributed system frameworks. The author then characterizes mobile agent systems, showing such system's intrinsic differences from Jini and some of their basic problems. Finally, he discusses how agent systems could use the Jini system approach to solve some of these intrinsic problems.     

Efficiency analysis of information technology and online social networks management: An integrated DEA-model assessment

This paper analyses the relationship between productive efficiency and online-social-networks (OSN) in Spanish telecommunications firms. A data-envelopment-analysis (DEA) is used and several indicators of business “social Media” activities are incorporated. A super-efficiency analysis and bootstrapping techniques are performed to increase the model's robustness and accuracy. Then, a logistic regression model is applied to characterise factors and drivers of good performance in OSN. Results reveal the company's ability to absorb and utilise OSNs as a key factor in improving the productive efficiency. This paper presents a model for assessing the strategic performance of the presence and activity in OSN.     

Thermoelectric and mechanical properties of melt spun and spark plasma sintered n-type Yb- and Ba-filled skutterudites

Here we present thermoelectric and mechanical properties of n-type filled-skutterudites produced by a combination of melt spinning of pre-melted charges with subsequent consolidation by spark plasma sintering, a process we refer to as MS-SPS. This combination of processing steps leads to phase-pure n-type filled-skutterudites and obviates more energy and time intensive annealing steps. We show that both the thermoelectric properties and the tensile fracture strength compare favorably to materials made by traditional methods. The process is scalable to at least 80 g billets, such that the transport properties measured on test bars harvested from these larger billets compare favorably to those measured on lab-scale billets (5 g total billet mass). ZT values approaching 1.1 at 750 K were observed in materials made by MS-SPS. In addition, the tensile fracture strength of test bars cut from an 80 g billet is ∼128 MPa at room temperature and decreases with increasing temperature. Fractography of the test bars reveals that the majority failed due to surface and edge flaws with few failures due to volume type flaws. This indicates that the powder metallurgical methods employed to produce these samples is mature.     

Shared online spreadsheets and hidden profiles: Technological effects on dyad decision strategy

We report a study in which dyads use Instant Messaging to agree a preference among a set of three apartments. The information given to participants is partially overlapping, and contains a “hidden profile” (HP), such that a single apartment emerges as the best according to an unweighted sum of feature values only if dyad members pool information that is presented to only one of them. When dyads were additionally provided with a shared online spreadsheet, their decision strategy was more likely to be compensatory and relatively exhaustive, even if the distribution of importance among the cues in which the apartments vary meant that a “fast and frugal” heuristic such as take-the-best would be a rational strategy. This study shows the potential of classic experimental tasks, the HP task in particular, for understanding technological constraints on group decision making and signals the importance of understanding decision-making strategies, and the potential of fast and frugal heuristics, for informing the design of decision support systems.