On the length of arcs in labyrinth fractals

Monatshefte für Mathematik - Labyrinth fractals are self-similar dendrites in the unit square that are defined with the help of a labyrinth set or a labyrinth pattern. In the case when the...     

Nanocomposites based on carbon nanotubes and redox-active polymers synthesized in a deep eutectic solvent as a new electrochemical sensing platform

Microchimica Acta - The redox polymer poly(methylene blue) was synthesized by electropolymerization in ethaline deep eutectic solvent (PMBDES), and employed in a new nanostructured composite...     

Stable Isotope Fingerprinting for Pharmaceutical Authentication

ABSTRACT

The ¹³C stable isotopic composition of 38 pharmaceutical products was investigated for six medicine analgesics classes ibuprofen, diclofenac, paracetamol, metamizole, ketoprofene, and combinations containing paracetamol to evaluate differences between manufacturers and production batches. Complementary measurements were performed by inductively coupled plasma-mass spectrometry. Linear discriminant analysis was applied on experimental obtained data set for differentiation of three investigated drug types. The carbon isotopic compositions were between ?32.9 and ?22.6‰. The lowest values of ¹³C (mean of ?31.3‰) were obtained for metamizole from all six categories of investigated analgesics. The highest δ¹³C values were obtained for diclofenac (mean of ?25.9‰). The most accurate elemental predictors were V, Al, Sb, As, Pb, and Mn.     

Univalence Criteria Starting from the Method of Loewner Chains

The paper continues the work of Royster (Duke Math J 19:447–457, 1952), Mocanu [Mathematica (Cluj) 22(1):77–83, 1980; Mathematica (Cluj) 29:49–55, 1987], Cristea [Mathematica (Cluj) 36(2):137–144, 1994; Complex Var 42:333–345, 2000; Mathematica (Cluj) 43(1):23–34, 2001; Mathematica (Cluj), 2010, to appear; Teoria Topologica a Functiilor Analitice, Editura Universitatii Bucuresti, Romania, 1999] of extending univalence criteria for complex mappings to C ¹ mappings. We improve now the method of Loewner chains which is usually used in complex univalence theory for proving univalence criteria or for proving quasiconformal extensions of holomorphic mappings f : B → C ⁿ to C ⁿ . The results are surprisingly strong. We show that the usual results from the theory, like Becker’s univalence criteria remain true for C ¹ mappings and since we use a stronger form of Loewner’s theory, we obtain results which are stronger even for holomorphic mappings f : B → C ⁿ . In our main result (Theorem 4.1) we end the researches dedicated to quasiconformal extensions of K-quasiregular and holomorphic mappings f : B → C ⁿ to C ⁿ . We show that a C ¹ quasiconformal map f : B → C ⁿ can be extended to a quasiconformal map F : C ⁿ → C ⁿ , without any metric condition imposed to the map f.     

Exploring the Research Progress about the Applications of Cyclodextrins and Nanomaterials in Electroanalysis

Cyclodextrins and nanomaterials are widely used in the achievement of powerful platforms in supramolecular chemistry and nanotechnology. The relatively hydrophobic internal cavity of the CDs selectively retains molecules having the proper geometry, while the hydrophilic exterior allows CDs to improve the dispersibility and molecular recognition. The nanomaterials provide higher surface area, good conductivity, and electrocatalytic effect. The use of nanomaterials and CDs in electrochemical sensors’ design allows the development of a large variety of devices, explaining the increasing number of papers in the last years that are discussed in this review.     

Pulsed Electron-Nuclear Double Resonance in the Fourier Regime

Nuclear magnetic resonance (NMR) spectroscopy provides atomic-level molecular structural information. However, in molecules containing unpaired electron spins, NMR signals are difficult to measure directly. In such cases, data is obtained using the electron-nuclear double resonance (ENDOR) method, where nuclei are detected through their interaction with nearby unpaired electron spins. Unfortunately, electron spins spread the ENDOR signals, which challenges current acquisition techniques, often resulting in low spectral resolution that provides limited structural details. Here, we show that by using miniature microwave resonators to detect a small number of electron spins, integrated with miniature NMR coils, one can excite and detect a wide bandwidth of ENDOR data in a single pulse. This facilitates the measurement of ENDOR spectra with narrow lines spread over a large frequency range at much better spectral resolution than conventional approaches, which helps reveal details of the paramagnetic molecules’ chemical structure that were not accessible before.     

X-ray structures and pharmacological activities of lidocaine derivatives

The molecular and crystal structures of the lidocaine analogs 2-(pyrazol-1-yl)-2′-methylacetanilide (1), 2-(3,5-dimethyl-4-iodo-pyrazol-1-yl)-2′-methylacetanilide (2), 2-(3,5-dimethyl-4-iodo-pyrazol-1-yl)-3′-methylacetanilide (3), and 2-(pyrazol-1-yl)-4′-methylacetanilide (4), are reported, with a summary of their pharmacological activities. In this series, the moiety comprising the heterocyclic ring and the amide alkyl linker displays a common conformation. Molecules of 1–4 form identical hydrogen bonded motifs in their crystals, namely linear chains via intermolecular N–H···O=C hydrogen bonding. Moderate anesthetic and anti-arrhythmic potencies recorded for 1–4 relative to lidocaine are countered by their significantly lower toxicities.     

Rose Hips,a Valuable Source of Antioxidants to Improve Gingerbread Characteristics

The present study analyzes the complex of bioactive compounds from rose hips pulp powder (RHP) obtained after separating the seeds from Rosa canina L. in order to obtain the oil. The extract prepared from RHP was characterized in terms of the total content of polyphenols, flavonoids, cinnamic acids, flavonols, carotenoids, but also the content of individual polyphenols and carotenoids, antioxidant activity, and CIELab color parameters. The effects of some salts, potentially present in foods, and pH variations were examined to predict possible interactions that could occur when adding rosehip pulp as a food component. The results turned out to be a high content of polyphenols, carotenoids and antioxidant activity. The main phenolic components are procyanidin B1, chlorogenic acid, epicatechin, procyanidin B2, gallic acid, salicylic acid, and catechin. The carotenoid complex includes all-trans-β-carotene, all-trans-lycopene, zeaxanthin, α-cryptoxanthin, β-cryptoxanthin, rubixanthin, cis-β-carotene, cis-γ-carotene and cis-lycopene. The addition of CaCl₂ and NaCl to the RHP extract reduced the antioxidant activity and the strong acidic environment (pH to 2.5) decreased the antioxidant activity by 29%. The addition of rose hip powder to gingerbread has improved its general characteristics, and increased its antioxidant activity and microbiological stability, the effects of 4% RHP being the most important.     

Poly(siloxane‐urethane) crosslinked structures obtained by sol‐gel technique

Poly(siloxane‐urethane) crosslinked structures were prepared from isophorone diisocyanate, α,ω‐bis(hydroxybutyl)oligodimethylsiloxane and a new hybrid diol containing hydrolysable Si? OC₂H₅ groups besides OH groups. The latest was synthesized by the acid‐catalyzed reaction between 1,3‐bis(3‐glycidoxypropyl)tetramethyldisiloxane and 3‐aminopropyltriethoxysilane. The formations of the urethane groups along the polymer backbone as well as the formation of the silica domains were first confirmed by the presence of the specific bands in Fourier transform infrared spectra. The resulted materials were characterized using differential scanning calorimetry, thermogravimetric analysis and scanning electron microscopy. The results of the dynamic mechanical analysis (DMA) performed at various frequencies revealed shape memory capabilities for some of the obtained structures. The silica formed because of the hydrolysis‐condensation reactions proved to have reinforcing effect upon siloxane‐urethane structure also evidenced by DMA and increasing water vapor sorption capacity as was measured by dynamic vapor sorption. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011