A Novel Label Free Electrochemical Magnetoimmunosensor for Human Interleukin‐6 Quantification in Serum

A novel magnetoimmunosensor, designed for sensitive and selective quantification of interleukin 6, is herein reported. The experimental design involves the covalent immobilization of anti‐interleukin 6 antibody through an amidic bond formed with the carboxyl functionalities provided at the surface of protein G‐functionalized magnetic microparticles, assuring a sandwich‐type immunoassay with electrochemical label free detection. All the experimental parameters involved in the elaboration and testing protocol were optimized. A linear calibration plot between the charge transfer resistance and the logarithmic concentration of interleukin‐6 was achieved in the 1 pg mL^?1 to 1 μg mL^?1 range. A limit of quantification of 1 pg mL^?1 and a detection limit of 0.3 pg mL^?1 were obtained. The optimized magnetoimmunosensor showed an excellent selectivity against some potentially interfering proteins and has been successfully applied for the determination of target protein in human serum, proving its clinical relevance.     

Properties of vinylpyrrolidone-tert-butylphenyl methacrylate copolymers in solution

Copolymers of vinylpyrrolidone-p-tert-butylphenyl methacrylate (VP-MBPh) of several compositions were prepared by polymerization in benzene at 50°C using α′α′-azobisisobutyronitrile as initiator. Three of the copolymers were fractionated. Number-average molecular weights of fractionated samples were determined by osmotic pressure in benzene or 2-propanol. Kuhn–Mark–Houwink relations were established in benzene, chloroform, and 2-propanol. From the relation between M _n and the intrinsic viscosity (η), it appears that these random copolymers behave as predicted by the theory for flexible polymers. Abnormal viscometric behavior shown by one of the copolymers in nitromethane at 29°C (the theta temperature) is discussed. The Stockmayer–Fixman semiempirical method was used for estimating unperturbed dimensions from viscosity data obtained in chloroform, a good common solvent. Values of the viscosity parameter K_θ increase with the content of p-tert-butylphenyl methacrylate. In general, experimental K_θ values are higher than those calculated for the homopolymers. Excluded-volume parameters are estimated and discussed in relation to repulsive interactions between unlike monomer units.     

The need is compelling to perform an experiment capable of determining the velocity of gravitational interaction

In earlier papers some proposals were made concerning experiments that could lead to the determination of the velocity of the gravitational interaction. This paper points out that this determination can only be achieved by measuring the delayed gravitational field and not by measuring the propagation velocity of gravitational radiation, which remains a controversial problem, both theoretically and experimentally. The possibility is shown of the existence of a gravitational effect not unlike the Poynting-Robertson light effect and the importance is discussed of its determination for space and astronomical research. Some of the proposed mechanisms for explaining the gravitational interaction are reviewed and their nonviability is objectively pointed out. Finally, conclusions are drawn as to the necessity of carrying out experiments to determine the velocity of the gravitational interaction.     

Massenspektrometrische Untersuchungen von Isomeren Stickstoffverbindungen des Dibenzofurans

The mass spectra and the fragmentation patterns of amino-, acetamino- and nitrodibenzo-furan isomers have been investigated. Significant differences between the particular isomers are observed which are partly due to intramolecular hydrogen bond bridges, ortho effect or resonance stabilisation.     

On the free vibrations of a piezoceramic hollow sphere

The aim of the paper is to analyze the free vibrations of a piezoceramic hollow sphere with radial polarization. Using the cnoidal method and a genetic algorithm solves the equations of a radially inhomogeneous spherically isotropic piezoelastic medium. The Reddy and the cosine laws represent the functionally graded property of material. It is seen that for a piezoceramic hollow sphere, the piezoelectric effect consists in increasing the values for the natural frequencies in the specified classes of vibrations.     

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.     

Polyelectrolyte complexes. II. Specific aspects of the formation of polycation/dye/polyanion complexes

We report on the formation of the polycation/dye/polyanion (PC/D/PA) complexes by the interaction between nonstoichiometric polycation/dye (PC/D) complexes with polyanions. Polycations differed in their content of the (N,N‐dimethyl‐2‐hydroxypropylene ammonium chloride) units in the main chain. Poly(sodium acrylate) (NaPA), poly(sodium 2‐acrylamido‐2‐methylpropane sulfonate) (NaPAMPS) and poly(sodium styrenesulfonate) (NaPSS) were used as polyanions. Crystal Ponceau 6R (CP6R) and Ponceau 4R (P4R) with two or three sulfonic groups were used as anionic dyes. The interaction between nonstoichiometric PC/D complexes and polyanions was followed by UV‐VIS spectroscopy, viscometry, and conductometry measurements. Formation of PC/D/PA complexes takes place mainly by the electrostatic interaction between the polyanion and the free positive charges of the nonstoichiometric PC/D complex. The stoichiometry and the stability of the tricomponent complexes depended on the polycation structure, the structure and molecular weight of polyanion, the dye structure, and the P/D molar ratio. A high amount of the dye was excluded from the complex before the end point when a branched polycation was used. The higher the solubility of the dye the lower the stability of the PC/D/PA complexes. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 409–418, 1999     

Polyelectrolyte complexes. I. Synthesis and characterization of some insoluble polyanion-polycation complexes

The synthesis of some water-insoluble synthetic polyelectrolyte complexes formed between a weak polyanion and a strong polycation was followed. Sodium salts of poly(acrylic acid) and of some copolymers of acrylic acid with itaconic acid or maleic acid were used as anionic polymers. Cationic polyelectrolytes with quaternary ammonium salt groups in the main chain were used as strong polycations. The cationic polymers were different as concerns both the content of quaternary nitrogen atoms and the degree of branching. The complex formation was followed by the variation of the conductivity and of the specific viscosity of the reaction medium as well as by the turbidimetric titration versus the unit molar ratio polyanion/polycation. The deviation of the endpoint from stoichiometry was influenced mainly by the structure of the complementary polymers and by their molecular weights. The greater the structural differences, the higher the endpoint deviation from stoichiometry. Only insoluble polyelectrolyte complexes (PEC) were obtained in all the polyanion/polycation systems taken into account. The PECs were separated and characterized by elemental and spectral analyses as compared with the complementary polymers. © 1996 John Wiley & Sons, Inc.     

X-ray Structures of Pharmacologically Active 2-(3,5-Dimethyl-pyrazol-1-yl)-methylacetanilides

Abstract X-ray structures of three pharmacologically active lidocaine analogs, containing a common, substituted pyrazole moiety as the basic residue and variously substituted phenyl rings as the hydrophobic residue, have been determined. This isomeric series comprises 2-(3,5-dimethyl-pyrazol-1-yl)-2′-methylacetanilide (1), 2-(3,5-dimethyl-pyrazol-1-yl)-3′-methylacetanilide monohydrate (2), and 2-(3,5-dimethyl-pyrazol-1-yl)-4′-methylacetanilide (3). Crystal data are 1: space group P2 ₁ /c with a = 4.7617(2), b = 11.5638(4), c = 23.603(1) ?, β = 90.736(2)°, Z = 4; 2: P2 ₁ /c with a = 4.7260(1), b = 13.7001(4), c = 21.7006(6) ?, β = 93.425(1)°, Z = 4; 3: P2 ₁ /n with a = 6.4103(3), b = 24.584(1), c = 8.4449(4) ?, β = 100.273(3)°, Z = 4. In 1–3, the amide bond is trans-planar but the basic and hydrophobic residues adopt different orientations relative to this plane. Hydrogen bonding in 1 and 3 is based on C(4) linear arrays whereas in the monohydrate 2, the presence of water gives rise to R ₄ ⁴ (16) ring motifs. A summary of the local anesthetic and anti-arrhythmic properties of 1–3 is provided. Graphical abstract X-ray Structures of Pharmacologically Active 2-(3,5-Dimethyl-pyrazol-1-yl)-methylacetanilides Christina Zalaru, Mino R. Caira, Mircea Iovu, and Elena Cristea The title compounds are lidocaine analogs that display local anesthetic and anti-arrhythmic activities. X-ray analyses revealed a range of solid-state conformations among these isomeric compounds as well as variation in hydrogen bonding schemes, namely C(4) (R = o-, p-CH3) and R44(16) (R = m-CH3, monohydrate crystal). 1,1-Os3(CO)9(μ-CO)(phen)