Semiotic open complex systems: Processes and behaviors

An H‐system is a conceptual or semiotic model of reality formed in the mind of the subject. Understanding the behavior of the system means being able to infer causal relationships that explain this system to the Observer‐subject, and therefore having access to mechanisms to construct a mental or ontological mathematical model of the system under study. A process is a mechanism involving a series of successive operations between stimuli and responses. © 2016 Wiley Periodicals, Inc. Complexity 21: 388–396, 2016     

Exploiting Sulphide Generation and Gas Diffusion Separation in a Flow System for Indirect Sulphite Determination in Wines and Fruit Juices

A flow system for sulphite determination in wines and fruit juice samples has been developed exploiting H₂S generation and gas diffusion separation. The composed sandwich gas diffusion cell was coupled in the flow manifold to permit sulphite reduction to H₂S and H₂S diffusion through a microporous PTFE membrane to produce methylene blue resulting from the reaction with N,N-dimethylphenylene diamine (DMPD) and Fe³⁺. The flow parameters were optimized, and the best results were obtained by using NaOH solution for H₂S collection. Interferences of H₂S, CO₂ and ascorbic acid were evaluated. Limits of detection (3σ) for the free and total sulfite were calculated at 0.12 and 0.25 mg L⁻¹, respectively. The results obtained by the proposed process were in agreement with the reference methods for a 95% confidence level.     

The mutual effect of a carbonyl polar bond and an endocyclic oxygen on the 1JC‐F coupling constant of fluorinated six‐membered rings

The ¹J_C‐F coupling constant can be useful to probe the conformational landscape of organofluorine compounds and the intramolecular interactions governing the stereochemistry of these compounds. Neighboring oxygen electron lone pairs and a carbonyl group relative to a C─F bond affect this coupling constant in an opposite way, and therefore, analysis of the interactions involving these entities simultaneously indicates which effect dominates ¹J_C‐F. Spin–spin coupling constant calculations for a series of fluorinated tetrahydropyrans, cyclohexanones, and dihydropyran‐3‐ones indicated that an electrostatic/dipolar interaction between the C─F and C═O bonds is more important than the steric interaction between the C─F bond and the oxygen electron lone pairs. An intuitive consequence of such outcome is that this interaction not only drives the coupling constant but can also be taken into account when aiming at the stereochemical control of functionalized organofluorine compounds.     

Surface plasmon resonance immunosensor for ErbB2 breast cancer biomarker determination in human serum and raw cancer cell lysates

A highly sensitive surface plasmon resonance (SPR) immunosensor for the important ErbB2 breast cancer biomarker has been developed. Optimization of the assay has been carried out, including signal enhancement employing gold nanoparticles (GNPs). The effect of the signal amplification of the GNPs has been also studied. The assay has been tested with clinically relevant matrices. Results in 50% human serum yielded a LOD of 180 pg mL⁻¹ which is a concentration 83 times lower than the clinical cut-off. Raw lysates from model breast cancer cell lines (SK-BR-3, MCF-7 and MDA-MB-436) have been also assayed and higher quantities of the ErbB2 protein were clearly observed in the ErbB2 over-expressing case (SK-BR-3). The results confirmed that the simple and highly sensitive SPR immunosensor represents a feasible tool for ErbB2 detection.     

Simultaneous determination of multiclass preservatives including isothiazolinones and benzophenone‐type UV filters in household and personal care products by micellar electrokinetic chromatography

In this work, a simple and reliable micellar electrokinetic chromatography method for the separation and quantification of 14 preservatives, including isothiazolinones, and two benzophenone‐type UV filters in household, cosmetic and personal care products was developed. The selected priority compounds are widely used as ingredients in many personal care products, and are included in the European Regulation concerning cosmetic products. The electrophoretic separation parameters were optimized by means of a modified chromatographic response function in combination with an experimental design, namely a central composite design. After optimization of experimental conditions, the BGE selected for the separation of the targets consisted of 60 mM SDS, 18 mM sodium tetraborate, pH 9.4 and 10% v/v methanol. The MEKC method was checked in terms of linearity, LODs and quantification, repeatability, intermediate precision, and accuracy, providing appropriate values (i.e. R² ≥ 0.992, repeatability RSD values ?9%, and accuracy 90–115%). Applicability of the validated method was successfully assessed by quantifying preservatives and UV filters in commercial consumer products.     

A flow-injection biamperometric method for determination of pantoprazole in pharmaceutical tablets

A flow-injection biamperometric method for determination of pantoprazole (PTZ) in pharmaceutical tablets is reported for the first time. The reversible redox couples Fe3+/Fe2+, Fe(CN)6(3-)/Fe(CN)6(4-), Ce4+/Ce3+, VO3(-)NO2+, and I2/I- were tested as indicating redox systems for biamperometric determination of PTZ in a flow-injection assembly with optimized flow parameters. The best results were obtained using V03(-)NO2+, which showed to be a selective and sensitive biamperometric indicating system for PTZ even in the presence of excipients and antioxidants that typically are found in drugs. The analytical graph was linear (r = 0.99945) in the range from 10 to 100 mg/L using 25 mmol/L VO3(-) as the reagent and water as the carrier stream and applying 100 mV between the 2 platinum wire electrodes. The limits of detection and quantitation were 200 and 667 microg/L, respectively, with a sensibility of calibration of 22.6 mV/mg/L. The proposed method was successfully applied to determine PTZ in commercial pharmaceutical tablets with a mean relative error of 1.60% (n = 5) and mean relative standard deviation of 3.10%. Recoveries close to 100% showed good agreement between the expected amount of PTZ in tablets (40 mg) and the results found by the application of the proposed method and demonstrated that the formulations used in the tablet compositions do not interfere in the PTZ analysis. The system had good stability, with a relative standard deviation of 3.80% for 9 sequential injections of a 60 mg/L PTZ solution. A sampling rate of about 100 samples/h was obtained.     

The behaviour of the $$\overline{W}$$ -construction on the homotopy theory of bisimplicial sets

The codiagonal functor \(\overline{W}\) transfers a Quillen closed model structure on the bisimplicial set category from the ordinary model category of simplicial sets. This bisimplicial model structure is different from the so called Moerdijk model structure, which is similarly transferred from simplicial sets but through the diagonal functor. We show the mutual relationship of these two closed model structures on the category of bisimplicial sets.     

Frontal polymerizations carried out in Deep-Eutectic mixtures providing both the monomers and the polymerization medium

Deep Eutectic Solvents (DESs) based upon mixtures of Acrylic Acid (AA) or Methacrylic Acid (MAA) and Choline Chloride (CCl) demonstrated superior performance than regular organic solvents and even ionic liquids for frontal polymerizations (FPs). Full recovering of CCl after FP provided an interesting green character to the process.     

The SmA phase of a bent-core V-shaped compound: structure and electric-field response

The smectic A (SmA) phase of a V-shaped mesogen with a molecular bending angle of 60° was studied. According to X-ray measurements, the molecules are arranged with the ‘bow-string’ direction parallel to the smectic layer. This point was confirmed by birefringence analysis and the result is compatible with a non-polar structure. A detailed study of the (001) smectic layer reflection versus temperature was also carried out to determine the smectic translational order parameter. The results indicate that the material presents a high degree of translational order. In addition, the electric field response of the material was studied by means of second harmonic generation. This technique turned out to be highly sensitive to small structural distortions due to the V-shape of the constituent molecules.     

Development of stir-bar sorptive extraction–thermal desorption–gas chromatography–mass spectrometry for the analysis of musks in vegetables and amended soils

The aim of this study was to develop a sensitive and environment-friendly method based on stir-bar sorptive extraction (SBSE) followed by thermal desorption–gas chromatography–mass spectrometry (TD–GC–MS) to determine 8 synthetic musks (musk ambrette, musk ketone, celestolide, tonalide, galaxolide, phantolide, traseolide, and cashmeran) in vegetables (lettuce, carrot, and pepper) and amended soil samples. In a first step sorptive extraction was studied both in the headspace (HSSE) and in the immerse mode (SBSE). The best results were obtained in the immersion mode which was further studied. The influence of the main factors: methanol (20%) and NaCl addition (0%), extraction temperature (40 °C) and time (180 min), extraction solvent volume (9 mL) and stirring rate (600 rpm) on the efficiency of SBSE was evaluated by means of experimental designs. In the case of TD, desorption time (10 min), desorption temperature (300 °C), cryo-focusing temperature (−30 °C), vent flow (75 mL/min) and vent pressure (7.2 psi) were studied using both a fractioned factorial design and a central composite design (CCD). The method was validated in terms of apparent recoveries (AR%), method detection limits (MDLs) and precision at two different concentration levels. Although quantification using instrumental calibration rendered odd results in most of the cases, satisfactory recoveries (74–126%) were obtained in the case of matrix-matched calibration approach for all of the analytes and matrices studied at the two concentration levels evaluated. MDLs in the range of 0.01–0.8 ng/g and 0.01–1.1 ng/g were obtained for vegetables and amended soil samples, respectively. RSD values within 1–23% were obtained for all the analytes and matrices. Finally, the method was applied to the determination of musks in vegetable and amended soil samples.