Quantifying Information without Entropy: Identifying Intermittent Disturbances in Dynamical Systems

A system’s response to disturbances in an internal or external driving signal can be characterized as performing an implicit computation, where the dynamics of the system are a manifestation of its new state holding some memory about those disturbances. Identifying small disturbances in the response signal requires detailed information about the dynamics of the inputs, which can be challenging. This paper presents a new method called the Information Impulse Function (IIF) for detecting and time-localizing small disturbances in system response data. The novelty of IIF is its ability to measure relative information content without using Boltzmann’s equation by modeling signal transmission as a series of dissipative steps. Since a detailed expression of the informational structure in the signal is achieved with IIF, it is ideal for detecting disturbances in the response signal, i.e., the system dynamics. Those findings are based on numerical studies of the topological structure of the dynamics of a nonlinear system due to perturbated driving signals. The IIF is compared to both the Permutation entropy and Shannon entropy to demonstrate its entropy-like relationship with system state and its degree of sensitivity to perturbations in a driving signal.     

Tuning of the Self-Threading of Ring-in-Ring Structures in Aqueous Media

A series of aryl-extended N-monoalkyl-4,4′-bipyridinium salts L (aryl=1,4-phenyl, 4,4′-biphenyl, 2,6-naphthyl and 9,10-anthracenyl) have been implemented by Pd^II/Pt^II-directed self-assembly into constitutionally dynamic systems (CDSs). As a result, the intended processes produced not only (en) M ₂ L ₂ (en=ethylenediamine) metallacyclic species but also (en) M ₄ L ₄ ring-in-ring aggregates, in equilibrium with the former, as a consequence of the hydrophobic nature of the aryl rings within the 4,4′-bipyridinium scaffold. The key feature of the obtained dynamic systems is the possibility of modulating their response against external stimuli by modifying the hydrophobic character of the ligand. While the different dynamic libraries follow the same trends upon changes in concentration, temperature, polarity of the medium, or addition of an aromatic chemical effector, subtle changes in the ligand hydrophobic core results in a fine-tuning of the speciation when applying a certain degree of the different stimulus. The exception is the anthracene-containing derivative, which does not form inclusion complexes or self-threaded structures.     

Finding attractors of continuous-time systems by parameter switching

The review presents a parameter switching algorithm and his applications which allows numerical approximation of any attractor of a class of continuous-time dynamical systems depending linearly on a real parameter. The considered classes of systems are modeled by a general initial value problem which embeds dynamical systems continuous and discontinuous with respect to the state variable, of integer, and fractional order. The numerous results, presented in several papers, are systematized here on four representative known examples representing the four classes. The analytical proof of the algorithm convergence for the systems belonging to the continuous class is presented briefly, while for the other categories of systems, the convergence is numerically verified via computational tools. The utilized numerical tools necessary to apply the algorithm are contained in Appendices A, B, C, D and E.     

1‐Chloro‐3,6‐di­methoxy‐2,5‐di­methyl­benzene and 1‐chloro‐3,6‐di­methoxy‐2,4‐di­methyl­benzene

The title compounds, 1‐chloro‐3,6‐di­methoxy‐2,5‐di­methyl­benzene, (IIIa), and 1‐­chloro‐3,6‐di­methoxy‐2,4‐di­methyl­benzene, (IIIb), both C₁₀H₁₃ClO₂, were obtained from 2,5‐ and 2,6‐di­methyl‐1,4‐benzo­quinone, respectively, and are intermediates in the synthesis of ammonium quinone derivatives. The isomers have different substituents around the methoxy groups and crystallize in different space groups. In both mol­ecules, the methoxy groups each have different orientations with respect to the benzene ring. In both cases, one methoxy group lies in the plane of the ring and can participate in conjugation with the aromatic system, while the second is almost perpendicular to the plane of the aromatic ring. The C—O—C bond angles around these substituents are also different: 117.5 (4) and 118.2 (3)° in (IIIa) and (IIIb), respectively, when the methoxy groups lie in the plane of the ring, and 114.7 (3) and 113.6 (3)° in (IIIa) and (IIIb), respectively, when they are out of the plane of the ring.     

Ligand‐Free Copper‐Catalyzed Negishi Coupling of Alkyl‐, Aryl‐, and Alkynylzinc Reagents with Heteroaryl Iodides

Reported herein is an unprecedented ligand‐free copper‐catalyzed cross‐coupling of alkyl‐, aryl‐, and alkynylzinc reagents with heteroaryl iodides. The reaction proceeds at room temperature for the coupling of primary, secondary, and tertiary alkylzinc reagents with heteroaryl iodides without rearrangement. An elevated temperature (100 °C) is required for aryl–heteroaryl and alkynyl–heteroaryl couplings.     

Reaction of 2-hydroxyethylhydrazine with a trifluoromethyl-β-diketone: Study and structural characterization of a new 5-hydroxy-5-trifluoromethyl-4,5-dihydropyrazole intermediate

The reaction of the β-diketone 4,4,4-trifluoro-1-pyridin-2-yl-butane-1,3-dione and the monosubstituted hydrazine 2-hydroxyethylhydrazine has been investigated. Two products have been identified, 2-(2-hydroxyethyl)-3-pyridin-2-yl-5-trifluoromethyl-4,5-dihydropyrazole (P) and 2-(3-pyridin-2-yl-5-trifluoromethylpyrazol-1-yl)ethanol (L) in proportion 2:8, when the reaction was done at room temperature in ethanol for 15 h. The preparation of P as a pure product was performed in ethanol at 0 °C for 7 h. P has been characterized by ¹H, ¹³C{¹H} and ¹⁹F{¹H} NMR spectroscopy and by other techniques as appropriate.     

Synthesis of furanyl and oxazolyl N‐substituted piperidine and imidazoline salts as potential agonists of M1 muscarinic receptors

Furanyl and oxazolyl N‐substituted imidazoline salts were prepared by reacting furanyl and oxazolyl esters with ethylenediamine and trimethyl aluminum, followed by the addition of methyl iodide or hydrogen chloride. The piperidinium salts were prepared by treating furanyl and oxazolyl chlorides with piperidine base, followed by the addition of methyl iodide or hydrogen chloride.     

Effect of Synthesis Parameters on Sol–Gel Silica Modified by Zirconia

An experimental strategy was developed to obtain mesoporous SiO₂-ZrO₂ mixed oxides via a sol–gel process, which involved the use of tetraethylorthosilicate (TEOS) and an inorganic Zr-containing salt. The effects of key process parameters on the properties of the materials were investigated, including the choice of Zr(IV) source (zirconium oxychloride or nitrate), the ZrO₂ content and the synthesis pressure (i.e. ambient pressure or hydrothermal conditions). The resulting solids were dried, calcined at 500 °C, and characterized by nitrogen physisorption, pyridine chemisorption, ²⁹Si Nuclear Magnetic Resonance and X-ray diffraction. The data revealed that mesoporous materials with very narrow pore diameter distribution were obtained when using the autoclave procedure from both zirconium nitrate and oxychloride salts. The surface areas and pore size distributions were a function of ZrO₂ content. Differences in acidity, as determined by pyridine adsorption, were observed depending on the synthesis parameters.     

Parallel and automated library synthesis of 2-long alkyl chain benzoazoles and azole[4,5-<Emphasis Type="BoldItalic">b</Emphasis>]pyridines under microwave irradiation

Summary A versatile route to 40-membered library of 2-long alkyl chain substituted benzoazoles (1 and 2) and azole[4,5-b]pyridines (3 and 4) via microwave-assisted combinatorial synthesis was developed. The reactions were carried out in both monomode and multimode microwave oven. With the latter, all reactions were performed in high-throughput experimental settings consisting of an 8×5 combinatorial library designed to synthesize 40 compounds. Each step, from the addition of reagents to the recovery of final products, was automated. The microwave-assisted N-long chain alkylation reactions of 2-alkyl-1H-benzimidazole (1) and 2-alkyl-1H-benzimidazole[4,5-b] pyridines (3) were also studied.     

Determination of carbaryl, carbofuran and methiocarb in cucumbers and strawberries by monoclonal enzyme immunoassays and high-performance liquid chromatography with fluorescence detection. An analytical comparison

Carbaryl, carbofuran and methiocarb are three of the most important N-methylcarbamate pesticides. In the present work, the application of laboratory-developed monoclonal antibody-based enzyme-linked immunosorbent assays (ELISAs) to the determination of these compounds in fruits and vegetables is described. Cucumbers and strawberries were spiked with the three carbamates at 10, 50 and 200 ppb. After extraction and clean-up, samples were analyzed by immunoassay and by HPLC with post-column derivatization and fluorescence detection (US Environmental Protection Agency Method 531.1). Results obtained by ELISA correlated well with those obtained by HPLC, both in terms of accuracy and precision. Recoveries were in the 60-90% range by ELISA and in the 50-90% range by HPLC, depending on the particular combination of commodity, pesticide, and fortification level under consideration. ELISAs were also applied to the analysis of non-purified sample extracts with excellent results: recoveries close to 100% were obtained, while maintaining similar precision values. This approach avoids the use of solid-phase extraction columns, saves time, and considerably increases the sample throughput. Results clearly indicate that the developed immunoassays may be suitable for the quantitative and reliable determination of carbaryl, carbofuran and methiocarb in fruits and vegetables even without including clean-up steps. These considerations make these ELISAs very useful analytical tools for monitoring and regulatory programs, without the need of complex and expensive instrumentation.