Characterization of ethylene/propylene copolymers by means of a GPC-4D technique

Copolymer composition and comonomer distribution are important magnitudes in polymer material that have a big effect on different kind of properties and consequently there are several ways to study.In this work several ethylene/propylene copolymers synthesized with two different metallocene catalysts and a Ziegler–Natta catalyst and covering a wide composition range were studied. Characterization was carried out by nuclear magnetic resonance (¹³C NMR) and by gel permeation chromatography with 4 detectors (GPC-4D): refractive index, viscosity, multi-angle light scattering and infrared detectors.Different behaviour in the comonomer distribution along the molecular weight was obtained for metallocene and for ZN copolymers as expected due to the differences between these catalytic systems. Nevertheless, Ziegler–Natta copolymers present more homogeneous comonomer distribution due to the synthesis method. Study of conformation of chains in solution was improved by defining the scaling law of R_g against the number of repeat units because it avoids the effect of the repetitive unit size. Both metallocene copolymer sets show similar dependence of q value with the copolymer composition, however Ziegler–Natta copolymers show different behaviour with q values independent on copolymer composition. This different behaviour has been related with the effects of the heterogeneity of the ethylene distribution and of the molecular weight of the samples.     

Sandor’s inequality for Sugeno integrals

In this paper we prove a fuzzy integral inequality for convex functions. Our results improve recent results that appear in literature. Some examples are given to illustrate our theorems.     

Optical sectioning by two-pinhole confocal fluorescence microscopy

A two-pinhole axially superresolving confocal fluorescence imaging system is presented. Based on the concept of subtractive incoherent imaging, the system described here is equipped with a zero-focus complex-transmittance pupil filter in one of the collector paths. The optical sectioning capacity of the system is 25% superior to that of a free-pupil one-pinhole instrument.     

Docking and quantitative structure–activity relationship studies for sulfonyl hydrazides as inhibitors of cytosolic human branched-chain amino acid aminotransferase

We have performed the docking of sulfonyl hydrazides complexed with cytosolic branched-chain amino acid aminotransferase (BCATc) to study the orientations and preferred active conformations of these inhibitors. The study was conducted on a selected set of 20 compounds with variation in structure and activity. In addition, the predicted inhibitor concentration (IC₅₀) of the sulfonyl hydrazides as BCAT inhibitors were obtained by a quantitative structure–activity relationship (QSAR) method using three-dimensional (3D) vectors. We found that three-dimensional molecule representation of structures based on electron diffraction (3D-MoRSE) scheme contains the most relevant information related to the studied activity. The statistical parameters [cross-validate correlation coefficient (Q ² = 0.796) and fitted correlation coefficient (R ² = 0.899)] validated the quality of the 3D-MoRSE predictive model for 16 compounds. Additionally, this model adequately predicted four compounds that were not included in the training set.     

g-dominance: Reference point based dominance for multiobjective metaheuristics

One of the main tools for including decision maker (DM) preferences in the multiobjective optimization (MO) literature is the use of reference points and achievement scalarizing functions [A.P. Wierzbicki, The use of reference objectives in multiobjective optimization, in: G. Fandel, T. Gal (Eds.), Multiple-Criteria Decision Making Theory and Application, Springer-Verlag, New York, 1980, pp. 469–486.]. The core idea in these approaches is converting the original MO problem into a single-objective optimization problem through the use of a scalarizing function based on a reference point. As a result, a single efficient point adapted to the DM’s preferences is obtained. However, a single solution can be less interesting than an approximation of the efficient set around this area, as stated for example by Deb in [K. Deb, J. Sundar, N. Udaya Bhaskara Rao, S. Chaudhuri, Reference point based multiobjective optimization using evolutionary algorithms, International Journal of Computational Intelligence Research, 2(3) (2006) 273–286]. In this paper, we propose a variation of the concept of Pareto dominance, called g-dominance, which is based on the information included in a reference point and designed to be used with any MO evolutionary method or any MO metaheuristic. This concept will let us approximate the efficient set around the area of the most preferred point without using any scalarizing function. On the other hand, we will show how it can be easily used with any MO evolutionary method or any MO metaheuristic (just changing the dominance concept) and, to exemplify its use, we will show some results with some state-of-the-art-methods and some test problems.     

Using box indices in supporting comparison in multiobjective optimization

Because of the conflicting nature of criteria or objectives, solving a multiobjective optimization problem typically requires interaction with a decision maker who can specify preference information related to the objectives in the problem in question. Due to the difficulties of dealing with multiple objectives, the way information is presented plays a very important role. Questions posed to the decision maker must be simple enough and information shown must be easy to understand. For this purpose, visualization and graphical representations can be useful and constitute one of the main tools used in the literature. In this paper, we propose to use box indices to represent information related to different solution alternatives of multiobjective optimization problems involving at least three objectives. Box indices are an intelligible and easy to handle way to represent data. They are based on evaluating the solutions in a natural and rough enough scale in order to let the decision maker easily recognize the main characteristics of a solution at a glance and to facilitate comparison of two or more solutions in an easily understandable way.     

Expanding the carbo‐Benzene Chemical Space for Electron‐Accepting Ability: Trifluorotolyl/Tertiobutyl Substitution Balance

With the view to altering the lipophilicity and electron accepting ability of the tetraphenyl‐carbo‐benzene scaffold, peripheral fluorination of the C₁₈ ring through aromatic linkers was envisaged from the C₁₈Ph₆ and o‐^tBu₂C₁₈Ph₄ references, by replacement of two Ph substituents with two p‐CF₃‐C₆H₄ counterparts (^FTol). The synthesis relied on a [8+10] macrocyclization involving a common bis(trifluorotolyl)‐tetraynedione, followed by reductive aromatization of the resulting [6]pericyclynediols. While p‐^FTol₂C₁₈Ph₄ proved to be hardly tractable due to an extremely low solubility, p‐^FTol₂‐o‐^tBu₂C₁₈Ph₂ could be extensively studied by X‐ray crystallography, NMR and UV/Vis spectroscopy, voltammetry, STM imaging of monolayers, and AFM imaging of binary films with P3HT or PC₇₁BM fabricated by spin‐coating for organic photovoltaic cells and J?V curve measurement thereof. The electronic and polarity properties are correlated with moderate but consistent electron‐withdrawing effects of the CF₃ groups, in agreement with the DFT‐calculated frontier orbitals and multipole moments. The results provide guidelines for optimization of fluorinated carbo‐benzene targets.     

Molecular mechanics calculation on the hydroxyl stretching frequency in saturated alcohols Part III. Acyclic alcohols

The applicability of an earlier developed MM2/CNDO scheme for the accurate calculation of ν_OH (gas) in saturated alcohols, is investigated for acyclic compounds containing -t-butyl and -ethyl groups. Experimental ν_OH gas frequencies for the selected alcohols are assigned to the various OH rotamers. The predicted ν_OH frequencies are in general lower than the experimental values. Calculated rotamer population is consistent with data from CCl₄ solutions. Results from the calculations show that, at least for alcohols containing -t-butyl groups, predicted ν_OH frequencies can be employed to assist in the assignment of the experimental values.