Stochastic molecular descriptors for polymers. 4. Study of complex mixtures with topological indices of mass spectra spiral and star networks: The blood proteome case

The Quantitative Structure-Property Relationships (QSPRs) based on Graph or Network Theory are important for predicting the properties of polymeric systems. In the three previous papers of this series (Polymer 45 (2004) 3845-3853; Polymer 46 (2005) 2791-2798; and Polymer 46 (2005) 6461-6473) we focused on the uses of molecular graph parameters called topological indices (TIs) to link the structure of polymers with their biological properties. However, there has been little effort to extend these TIs to the study of complex mixtures of artificial polymers or biopolymers such as nucleic acids and proteins. In this sense, Blood Proteome (BP) is one of the most important and complex mixtures containing protein polymers. For instance, outcomes obtained by Mass Spectrometry (MS) analysis of BP are very useful for the early detection of diseases and drug-induced toxicities. Here, we use two Spiral and Star Network representations of the MS outcomes and defined a new type of TIs. The new TIs introduced here are the spectral moments (π_k) of the stochastic matrix associated to the Spiral graph and describe non-linear relationships between the different regions of the MS characteristic of BP. We used the MARCH-INSIDE approach to calculate the π_k(SN) of different BP samples and S2SNet to determine several Star graph TIs. In the second step, we develop the corresponding Quantitative Proteome-Property Relationship (QPPR) models using the Linear Discriminant Analysis (LDA). QPPRs are the analogues of QSPRs in the case of complex biopolymer mixtures. Specifically, the new QPPRs derived here may be used to detect drug-induced cardiac toxicities from BP samples. Different Machine Learning classification algorithms were used to fit the QPPRs based on π_k(SN), showing J48 decision tree classifier to have the best performance. These results suggest that the present approach captures important features of the complex biopolymers mixtures and opens new opportunities to the application of the idea supporting classic QSPRs in polymer sciences.     

Ethnic Group Identification and Group Evaluation Among Minority and Majority Groups: Testing the Multiculturalism Hypothesis.

Following social identity theory, the author hypothesized that members of minority groups are more likely than majority group members to endorse multiculturalism more strongly and assimilationist thinking less strongly. In addition, the multiculturalism hypothesis proposes that the more minority groups endorse the ideology of multiculturalism (or assimilationism), the more (or less) likely they will be to identify with their ethnic in-group and to show positive in-group evaluation. In contrast, the more majority group members endorse multiculturalism (or assimilationism), the less (or more) likely they are to identify with their ethnic group and to show negative out-group evaluation. Results from 4 studies (correlational and experimental) provide support for this hypothesis among Dutch and Turkish participants living in the Netherlands. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cu content dependence of Cu<Subscript>2</Subscript>Zn(SnGe)Se<Subscript>4</Subscript> solar cells prepared by using sequential thermal evaporation technique of Cu/Sn/Cu/Zn/Ge stacked layers

The doping of Cu₂ZnSnSe₄ semiconductor with Ge element has demonstrated improvements to kesterite solar cell efficiency. However, the impact of different Cu concentrations on Cu₂ZnSnGeSe₄/CdS solar cell performance has been poorly studied. In this work, Cu₂ZnSnGeSe₄ thin films with different Cu contents were synthesized by selenization of sequential thermal evaporation precursors. Solar cells based on kesterite-type Cu₂ZnSnGeSe₄ (CZTGSe) were fabricated and the influence of the Cu thickness on the chemical composition and morphology of the layers and electro-optical properties of solar cells was studied. The stacking process was performed at room substrate temperature. Efficiency values in the range of 2.0–6.8% are reported as a function of Cu concentration. The highest efficiency of 6.8%, was achieved for solar cell with glass/Mo/CZTGSe/CdS/i-ZnO/ITO structure using the stacking of Cu (3 nm)/Sn (248 nm)/Cu (112 nm)/Zn (174 nm)/Ge (20 nm).     

Analytical study of a solution-processed diode based on ZnO nanoparticles using multi-walled carbon nanotubes as Schottky contact

Journal of Materials Science: Materials in Electronics - The search for good electrodes processed by solution has interested several niches to produce printed solar cells, lighting emitting diodes,...     

Colloidal aggregation induced by the reduction in pH and the synthesis of new molecular structures during the milk fermentation process

The use of different inocula in the milk‐to‐yoghurt transformation influences the kinetics of the fermentation process. The aim of this work was to study the kinetics induced by Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus (Lb–St). The milk‐to‐yoghurt transformation showed no delay in the production of lactic acid for yoghurt produced using Lactobacillus johnsonii with S. thermophilus (La1–St) or Lactobacillus casei with S. thermophilus (Lc1–St); the delays were 20–70 min and 40–80 min, respectively. The absence of delay was 1.0/min (Lb–St) as compared with 0.015/min (La1–St) and 0.7/min (Lc1–St). The kinetics was fitted using second‐order reaction.     

A topological sub-structural approach to the mutagenic activity in dental monomers. 3. Heterogeneous set of compounds

The topological sub-structural molecular design (TOPS-MODE) approach has been applied to the study of mutagenic properties in a heterogeneous set of dental monomers. A model able to describe close to 90% of the experimental variance in the values for mutagenic activity of 41 dental monomers through genetic algorithm was developed with the use of the mentioned approach. Also, a study for the determination of the optimal number of variables in the equation and potential outliers was carried out. Finally, the TOPS-MODE approach was used to derive the contribution of different fragments to the mutagenic activity.     

A novel dual mechanism in dye‐sensitized solar cells

An innovative dye‐sensitized solar cell based on achiote seeds with a new dual electrical generation mechanism is presented. This dye‐sensitized solar cell, in addition to the well‐known mechanism, where the conduction electrons are released from the dye molecules due to their interaction with photons, shows a distinct chemical mechanism that produces an effective electric current under dark conditions. Both mechanisms operate simultaneously; however, the electrical signal obtained from the photoelectrical mechanism is stronger. Additionally, during a rapid transition from darkness to illuminate conditions, non‐linear oscillations in the current signal are produced when the system is shifted rapidly far from equilibrium conditions. Copyright © 2017 John Wiley & Sons, Ltd.     

Quantitative structure-activity relationship studies for the prediction of antifungal activity of N-arylbenzenesulfonamides against Botrytis cinerea

The Botrytis cinerea is one of the most interesting fungal pathogens. It can infect almost every plant and plant part and cause early latent infections which damage the fruit before ripening. The QSAR is an alternative method for the research of new and better fungicides against B. cinerea. This paper describes the results of applying a topological sub-structural molecular design (TOPS-MODE) approach for predicting the antifungal activity of 28 N-arylbenzenesulfonamides. The model described 86.1% of the experimental variance, with a standard deviation of 0.223. Leave-one-out and leave-group-out cross validation was carried out with the aim of evaluating the predictive power of the model. The values of their respective squared correlations coefficients were 0.754 and 0.741. The TOPS-MODE approach was compared with three other predictive models, but none of these could explain more than 72.8% of the variance with the same number of variables. In addition, this approach enabled the assessment of the contribution of different bonds to antifungal activity, thereby making the relationships between structure and biological activity more transparent. It was found that the fungicidal activity of the chemicals analyzed was increased by the presence of a sulfonamide group bonded to two aromatics rings, making this group the most important of the molecule. The majority of the substituents present in the aromatic rings have an electron withdrawing effect and they contribute to a smaller degree than the sulfonamide group to the property under study. The aromatic moiety plays an important role in this activity; its contribution changes with different substituents. Generally, the nitro group has a positive and great contribution to the biological property but when this group is involved in some compounds in ortho effect with the SO2 moiety of the sulfonamide group a lower value of contribution is observed for both groups.     

A topological sub-structural approach to the mutagenic activity in dental monomers. 2. Cycloaliphatic epoxides

The topological sub-structural molecular design (TOPS-MODE) approach has been introduced for the study of mutagenic properties. The mutagenicity of 15 dental monomers was studied with this approach obtaining a good quantitative structure-toxicity model. For purposes of comparison, we employed seven different weights in the diagonal entries of the bond matrix in order to select the best TOPS-MODE model. In addition, our best model was compared with a model previously reported in the literature, and proved to be superior. Finally, the TOPS-MODE approach was used to derive the contribution of different fragments to the mutagenicity of all the compounds studied.