Green lubricants production from Nile tilapia waste and prediction of physical properties through molecular dynamics simulations

Fish farming is a worldwide growing activity and a large amount of residues is produced in this process. The present work describes a cleaner and sustainable way to produce new lubricants from fish waste oil. Oil extracted from the Nile tilapia (Oreochromis niloticus) viscera was utilized as raw material to produce basic oil for lubricants. The products were synthesized by esterification with polyols, trimethylolpropane (TMP) and pentaerythritol (PE), using p-toluenesulfonic acid (p-TSA) as catalyst. The synthesized esters were characterized by infrared (IR) and nuclear magnetic resonance (NMR). Computational methods were used to predict the physical characteristics of the material. In addition, the main physicochemical properties were evaluated, as well as the thermal behavior and toxicity of the products against Artemia salina. The synthesized esters showed high viscosity indexes (VI > 150) and viscosities that fit the degree of application ISO-46 and 150. Molecular dynamics simulations indicated that at room temperature the lubricants Tilapia fatty acid - trimethylolpropane ester (T-TMPE) and Tilapia fatty acid - pentaerythritol ester (T-PEE) are in liquid and gel states, respectively, confirming the experimental data. The products did not present toxicity against A. salina. In this research, we reinforce the potential of using tilapia oil from waste to produce green lubricants as a strategy to reduce damage to the environment, as well as the use of computational methods that collaborate to predict physical properties of lubricants.     

Semantic annotation for knowledge management: Requirements and a survey of the state of the art

While much of a company's knowledge can be found in text repositories, current content management systems have limited capabilities for structuring and interpreting documents. In the emerging Semantic Web, search, interpretation and aggregation can be addressed by ontology-based semantic mark-up. In this paper, we examine semantic annotation, identify a number of requirements, and review the current generation of semantic annotation systems. This analysis shows that, while there is still some way to go before semantic annotation tools will be able to address fully all the knowledge management needs, research in the area is active and making good progress.     

A Generalized Nash Equilibrium Model of Market Coupling in the European Power System

??Market Coupling?? is currently seen as the most advanced market design in the restructuring of the European electricity market. Market Coupling, by construction, introduces what is generally referred to as an incomplete market: it leaves several constraints out of the market and hence avoids pricing them. This may or may not have important consequences in practice depending on the case on hand. Quasi-Variational Inequality problems and the associated Generalized Nash Equilibrium can be used for representing incomplete markets. Recent papers propose methods for finding a set of solutions of Quasi-Variational Inequality problems. We apply one of these methods to a subproblem of market coupling namely the coordination of counter-trading. This problem is an illustration of a more general question encountered, for instance, in hierarchical planning in production management. We first discuss the economic interpretation of the Quasi-Variational Inequality problem. We then apply the algorithmic approach to a set of stylized case studies in order to illustrate the impact of different organizations of counter-trading. The paper emphasizes the structuring of the problem. A companion paper considers the full problem of Market Coupling and counter-trading and presents a more extensive numerical analysis.     

Estimating, testing, and comparing specific effects in structural equation models: The phantom model approach.

The phantom model approach for estimating, testing, and comparing specific effects within structural equation models (SEMs) is presented. The rationale underlying this novel method consists in representing the specific effect to be assessed as a total effect within a separate latent variable model, the phantom model that is added to the main model. The following favorable features characterize the method: (a) It enables the estimation, testing, and comparison of arbitrary specific effects for recursive and nonrecursive models with latent and manifest variables; (b) it enables the bootstrapping of confidence intervals; and (c) it can be applied with all standard SEM programs permitting latent variables, the specification of equality constraints, and the bootstrapping of total effects. These features along with the fact that no manipulation of matrices and formulas is required make the approach particularly suitable for applied researchers. The method is illustrated by means of 3 examples with real data sets. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Repair of Erosion Defects in Gun Barrels by Direct Laser Deposition

In recent years the development of functional carbide coatings follows the trend to use composite powders with fine grained hard particles. In addition to thermal spraying, laser cladding is a suitable surface technology in particular for dynamically loaded components, and it is widely used for the manufacturing of coatings as well as complex 3D structures. The paper presents an application addressing the repair of erosion defects in large gun barrels using a novel internal diameter laser cladding head. The most promising material systems are TiC- and VC-based metal-matrix composites. Samples were evaluated in a special erosion test that emulates realistic load conditions. In this test, the materials are exposed to extreme stresses by temperature and pressure shocks, a very reactive atmosphere and erosive particles. As result, TiC-based coatings showed the best performance, and they are applicable for both repair and surface protection of inner surfaces of components and tools.     

Indigo and Tyrian Purple – From Ancient Natural Dyes to Modern Organic Semiconductors

We describe the history of indigo dye and its derivative Tyrian purple, from their roles in the ancient world to recent research showing the semiconducting properties of indigoids. Indigoids are natural dyes that have been produced for centuries, and indigo is currently the most produced dye worldwide. Herein we review the history of these materials, their chemistry and physical properties, and their semiconducting characteristics in the solid state. Due to hydrogen bonding and π-stacking, indigo and Tyrian purple form highly-ordered crystalline thin films. Such films have been used to fabricate high-performance organic field-effect transistors with ambipolar charge transport, as well as complementary-like circuits. Mobility values were found to be in the range of 10⁻²–0.4 cm²/Vs. With performance on par with the best available organic semiconductors, indigoids demonstrate the potential of sustainable electronics based on biodegradable and biocompatible materials.     

Phase equilibria in SBR/polybutadiene elastomer blends: Application of Flory–Huggins theory

Blends of anionically-polymerized polybutadiene (BR) and styrene–butadiene copolymer (SBR) must be treated as mixtures of terpolymers and tetrapolymers, due to the presence of three different BR isomers: cis-1,4, trans-1,4, and vinyl-1,2. Moreover, in the absence of specific interactions or chemical reactions that strongly influence miscibility, structural characteristics of the component polymers, such as BR isomer content, SBR styrene content, monomer sequence distribution, molecular weight, and molecular weight distribution, are expected to have an increased role in determining the blend miscibility characteristics. Small angle neutron scattering (SANS) studies of SBR/BR blends have resulted in the computation of the monomer–monomer segmental interaction energetics via a Flory–Huggins treatment. This allows quantitative prediction of miscibility behavior as a function of polymer structure. We have used the Flory–Huggins chi parameters, describing the styrene/cis-1,4, styrene/trans-1,4, and cis-1,4/trans-1,4 segmental interactions, to identify certain blend combinations expected to exhibit phase transitions in an experimentally accessible temperature range. The appropriate polymers were synthesized, solution blended, and the blends analyzed via optical microscopy and thermal analysis. Our results show that the blend behavior, observed experimentally, is consistent with the calculated cloud point curves. © 1994 John Wiley & Sons, Inc.     

Improved selection strategy for multi-objective evolutionary algorithms with application to water distribution optimization problems

Multi-objective evolutionary algorithms (MOEAs) have been applied to water distribution system (WDS) optimization problems for over two decades. The selection strategy is a key component of an MOEA that determines the composition of a population, and thereby the evolutionary search process, which imitates natural selection by granting fitter individuals an increasing opportunity to reproduce. This paper proposes the convex hull contribution (CHC) selection strategy for generational MOEAs (CHC_Gen) as a novel selection strategy that is based on the CHC of solutions to the Pareto front in the objective space. Numerical experiments using a general MOEA framework demonstrate that the CHC_Gen selection strategy is able to outperform existing popular selection strategies (e.g., crowding distance, hypervolume contribution, and hybrid replacement selection). Moreover, it is illustrated that the CHC_Gen selection strategy is able to improve the performance of existing MOEAs such as NSGA-II and GALAXY. The conclusions are based on the results of six bi-objective WDS problems.