Predicting the Helical Sense of Poly(phenylacetylene)s from their Electron Circular Dichroism Spectra

The calculated ECD spectrum (time‐dependent density functional theory TD‐DFT) for small oligomers of polyphenylacetylenes (PPAs) show a very good match with the experimental spectra of the PPA polymers, particularly with the first Cotton band associated to the helical sense of the internal polyenic backbone. This has been proven with a series of PPAs representative of cis‐cisoidal, cis‐transoidal, compressed and stretched polyene backbones, with identical or opposite internal/external rotational senses and allows the prediction of the helical sense of the internal helix of a PPA directly from its CD spectra.     

Use of quasi-SMILES to model biological activity of “micelle–polymer” samples

The basic task of the drug discovery is the establishing of molecular structure of new pharmaceutical agents. To define the molecular structure is only half of the way to new drug. The transport of active molecules to appropriate targets in an organism should be elucidated in details. The selection of polymeric structures playing the role of basis for transport of therapeutic agents into the body is one of the ways to solve the task. Drug loading capacity (DLC) and critical micelle concentration (CMC) are measures of ability of “polymer–micelle” systems to be suitable for the process of the transport of therapeutic agents into an organism. Polymeric micelles are a type of complex multi-phase and multicomponent chemical process and can be used to transport drug into an organism. Prediction of ability of “micelle–polymer” systems to be a tool for transport of therapeutic agents to targets in organism is an important task. Models, which are a mathematical function of available eclectic information about architecture of micelles and polymers, are suggested. The eclectic data are represented via the so-called quasi-simplified molecular input-line entry system (SMILES), which are analogy of traditional SMILES. The quasi-SMILES contain some additional information besides the molecular architecture (physicochemical and biochemical conditions). Predictive potential of these models is good.

     

Applications of Carbon Dots for the Photocatalytic and Electrocatalytic Reduction of CO2

The photocatalytic and electrocatalytic conversion of CO₂ has the potential to provide valuable products, such as chemicals or fuels of interest, at low cost while maintaining a circular carbon cycle. In this context, carbon dots possess optical and electrochemical properties that make them suitable candidates to participate in the reaction, either as a single component or forming part of more elaborate catalytic systems. In this review, we describe several strategies where the carbon dots participate, both with amorphous and graphitic structures, in the photocatalysis or electrochemical catalysis of CO₂ to provide different carbon-containing products of interest. The role of the carbon dots is analyzed as a function of their redox and light absorption characteristics and their complementarity with other known catalytic systems. Moreover, detailed information about synthetic procedures is also reviewed.     

Preparation and characterization of a copper(II) compound with a new glycine Schiff base containing an ester function

Summary A new Schiff base was obtained from glycine and ethyl--ketocyclopentylcarboxylate. This forms a potassium salt K(Rgly)·H₂O, where Rgly=C₁₀H₁₄O₄N. From this salt a new copper(II) complex was prepared, Cu(Rgly)·2H₂O, where Rgly=C₁₀H₁₃O₄N (deprotonated Schiff base). The compounds were characterized by i.r. spectroscopy, differential thermal analysis (d.t.a.) and thermogravimetric analysis (t.g.). The activation energy corresponding to the dehydration process for compounds was determined. On the basis of spectral data, the copper compound is believed to be pentacoordinate and square pyramidal.     

The probability of choosing primitive sets

We generalize a theorem of Nymann that the density of points in Zd that are visible from the origin is 1/ζ(d), where ζ(a) is the Riemann zeta function . A subset S⊂Zd is called primitive if it is a Z-basis for the lattice Zd∩spanR(S), or, equivalently, if S can be completed to a Z-basis of Zd. We prove that if m points in Zd are chosen uniformly and independently at random from a large box, then as the size of the box goes to infinity, the probability that the points form a primitive set approaches 1/(ζ(d)ζ(d−1)?ζ(d−m+1)).     

Identification of structural alerts for liver and kidney toxicity using repeated dose toxicity data

Background

The potential for a compound to cause hepatotoxicity and nephrotoxicity is a matter of extreme interest for human health risk assessment. To assess liver and kidney toxicity, repeated-dose toxicity (RDT) studies are conducted mainly on rodents. However, these tests are expensive, time-consuming and require large numbers of animals. For early toxicity screening, in silico models can be applied, reducing the costs, time and animals used. Among in silico approaches, structure–activity relationship (SAR) methods, based on the identification of chemical substructures (structural alerts, SAs) related to a particular activity (toxicity), are widely employed.

Results

We identified and evaluated some SAs related to liver and kidney toxicity, using RDT data on rats taken from the hazard evaluation support system (HESS) database. We considered only SAs that gave the best percentages of true positives (TP).

Conclusions

It was not possible to assign an unambiguous mode of action for all the SAs, but a mechanistic explanation is provided for some of them. Such achievements may help in the early identification of liver and renal toxicity of substances.

     

New approach based on fuzzy logic and principal component analysis for the classification of two-dimensional maps in health and disease. Application to lymphomas

Two-dimensional (2D) electrophoresis is the most wide spread technique for the separation of proteins in biological systems. This technique produces 2D maps of high complexity, which creates difficulties in the comparison of different samples. The method proposed in this paper for the comparison of different 2D maps can be summarised in four steps: (a) digitalisation of the image; (b) fuzzyfication of the digitalised map in order to consider the variability of the two-dimensional electrophoretic separation; (c) decoding by principal component analysis of the previously obtained fuzzy maps, in order to reduce the system dimensionality; (d) classification analysis (linear discriminant analysis), in order to separate the samples contained in the dataset according to the classes present in said dataset. This method was applied to a dataset constituted by eight samples: four belonging to healthy human lymph-nodes and four deriving from non-Hodgkin lymphomas. The amount of fuzzyfication of the original map is governed by the sigma parameter. The larger the value, the more fuzzy theresulting transformed map. The effect of the fuzzyfication parameter was investigated, the optimal results being obtained for sigma = 1.75 and 2.25. Principal component analysis and linear discriminant analysis allowed the separation of the two classes of samples without any misclassification.     

Monitoring of an industrial process by multivariate control charts based on principal component analysis

The control and monitoring of an industrial process is performed in this paper by the multivariate control charts. The process analysed consists of the bottling of the entire production of 1999 of the sparkling wine "Asti Spumante". This process is characterised by a great number of variables that can be treated with multivariate techniques. The monitoring of the process performed with classical Shewhart charts is very dangerous because they do not take into account the presence of functional relationships between the variables. The industrial process was firstly analysed by multivariate control charts based on Principal Component Analysis. This approach allowed the identification of problems in the process and of their causes. Successively, the SMART Charts (Simultaneous Scores Monitoring And Residual Tracking) were built in order to study the process in its whole. In spite of the successful identification of the presence of problems in the monitored process, the Smart chart did not allow an easy identification of the special causes of variation which casued the problems themselves.     

dc Electrokinetics for spherical particles in salt-free concentrated suspensions including ion size effects

We study the electrophoretic mobility of spherical particles and the electrical conductivity in salt-free concentrated suspensions including finite ion size effects. An ideal salt-free suspension is composed of just charged colloidal particles and the added counterions that counterbalance their surface charge. In a very recent paper [Roa et al., Phys. Chem. Chem. Phys., 2011, 13, 3960-3968] we presented a model for the equilibrium electric double layer for this kind of suspensions considering the size of the counterions, and now we extend this work to analyze the response of the suspension under a static external electric field. The numerical results show the high importance of such corrections for moderate to high particle charges, especially when a region of closest approach of the counterions to the particle surface is considered. The present work sets the basis for further theoretical models with finite ion size corrections, concerning particularly the ac electrokinetics and rheology of such systems.