Determination of Hyaluronic Acid in a Chitosan-Based Formulation by RP C18 and HILIC LC–ESI-MS: an Evaluation of Matrix Effect

Two simple and fast C18 and HILIC liquid chromatography–electrospray mass spectrometry methods for the determination of hyaluronic acid (HA) in a mucoadhesive chitosan-based formulation were developed and validated. The performances of both methods were compared in terms of validation parameters and matrix effect. A simple sample preparation method based on sulphuric acid-based degradation was optimized for the detection of HA fragments (i.e. m/z 380 2-mer, m/z 759 4-mer, m/z 1,138 8-mer and m/z 1,518 16-mer). By operating under selected ion-monitoring mode, excellent selectivity towards chitosan fragments was obtained. For validation, good linearity, detection limits (<4 μg mL⁻¹) and precision (RSD % < 16 %) were generally obtained on matrix with both columns. However, HILIC column exhibited improved performances in terms of HA fragment separation and selectivity. By analyzing on the C18 column the chitosan-based formulation and sample extracts from pig mucosa treated with the formulation, matrix effects exhibited a dependence of signal suppression degree (ranging from 37 to 83 %) as a function of the HA fragment dimension. The HILIC column afforded instead a significantly reduced suppression degree (ranging from 1 to 16 %) and a better separation. These findings demonstrated the improved performances of the HILIC column with respect to conventional C18 mechanism for the analysis of HA fragments in complex matrices.

     

Simple outlier labeling based on quantile regression,with application to the steelmaking process

This paper introduces some methods for outlier identification in the regression setting, motivated by the analysis of steelmaking process data. The proposed methodology extends to the regression setting the boxplot rule, commonly used for outlier screening with univariate data. The focus here is on bivariate settings with a single covariate, but extensions are possible. The proposal is based on quantile regression, including an additional transformation parameter for selecting the best scale for linearity of the conditional quantiles. The resulting method is used to perform effective labeling of potential outliers, with a quite low computational complexity, allowing for simple implementation within statistical software as well as commonly used spreadsheets. Some simulation experiments have been carried out to study the swamping and masking properties of the proposal. The methodology is also illustrated by some real life examples, taking as the response variable the energy consumed in the melting process. Copyright © 2015 John Wiley & Sons, Ltd.     

Towards a Loop Quantum Gravity and Yang–Mills unification

We propose a new method of unifying gravity and the Standard Model by introducing a spin-foam model. We realize a unification between an SU(2)$\mathit{SU}(2)$ Yang–Mills interaction and 3D   general relativity by considering a constrained Spin(4)∼SO(4)$\mathrm{Spin}(4)\sim \mathit{SO}(4)$ Plebanski action. The theory is quantized à la   spin-foam by implementing the analogue of the simplicial constraints for the Spin(4)$\mathrm{Spin}(4)$ symmetry, providing a way to couple Yang–Mills fields to spin-foams. A natural 4D extension of the theory is introduced. We also present a way to recover 2-point correlation functions between the connections as a first way to implement scattering amplitudes between particle states, aiming to connect Loop Quantum Gravity to new physical predictions.     

Elements of Iso-, Geno-, Hyper-Mathematics for Matter, Their Isoduals for Antimatter, and Their Applications in Physics, Chemistry, and Biology

Pre-existing mathematical formulations are generally used for the treatment of new scientific problems. In this note we show that the construction of mathematical structures from open physical, chemical, and biological problems leads to new intriguing mathematics of increasing complexity called iso-, geno-, and hyper-mathematics for the treatment of matter in reversible, irreversible, and multi-valued conditions, respectively, plus anti-isomorphic images called isodual mathematics for the treatment of antimatter. These novel mathematics are based on the lifting of the multiplicative unit of ordinary fields (with characteristic zero) from its traditional value +1 into: (1) invertible, Hermitean, and single-valued units for isomathematics; (2) invertible, non-Hermitean, and single-valued units for genomathematics; and (3) invertible, non-Hermitean, and multi-valued units for hypermathematics; with corresponding liftings of the conventional associative product and consequential lifting of all branches of mathematics admitting a (left and right) multiplicative unit. An anti-Hermitean conjugation applied to the totality of quantities and their operation of the preceding mathematics characterizes the isodual mathematics. Intriguingly, the emerging formulations preserve the abstract axioms of conventional mathematics (that based on the unit +1). As such, the new formulations result to be new realizations of existing abstract mathematical axioms. We then show that the above mathematical advances permit corresponding liftings of conventional classical and quantum theories with a resolution of basic open problems in physics, chemistry, and biology, numerous experimental verifications, as well as new industrial applications.     

Near Field Stimulated Time of Flight Mass Surface Analyzer

This work describes a groundbreaking process that provides a direct highly localized measurement of the atomic mass on surfaces at room temperature. Employing an original system that joins a scanning tunneling microscopy (STM) device and a time of flight (TOF) mass analyzer, we could previously ionize surface atoms by the combination of an optical laser pulse and an electric pulse at the STM tip. Desorbed ions from a localized area were accelerated and detected by a TOF chamber. We will demonstrate in this paper that high localization and mass discrimination can be obtained even without the aid of an electric pulse from the tip. We reduced the angle of incidence of the laser beam to zero (laser beam parallel to the sample surface). In this condition we were able to demonstrate for the first time ionic desorption at a confinement level of the order of 5-10nm, an order of magnitude better than previous configurations.This paper was originally presented at the 11th Optical Near Field Workshop, which was held on June 28, 2002 at Tokyo Institute of Technology, Yokohama, organized by the Optical Near Field Group of the Optical Society of Japan, an affiliate of the Japan Society of Applied Physics.     

Atmospheric Pressure Plasma Discharge for Polysiloxane Thin Films Deposition and Comparison with Low Pressure Process

An atmospheric pressure dielectric barrier plasma discharge has been used to study a thin film deposition process. The DBD device is enclosed in a vacuum chamber and one of the electrodes is a rotating cylinder. Thus, this device is able to simulate continuous processing in arbitrary deposition condition of pressure and atmosphere composition. A deposition process of thin organosilicon films has been studied reproducing a nitrogen atmosphere with small admixtures of hexamethyldisiloxane (HMDSO) vapours. The plasma discharge has been characterized with optical emission spectroscopy and voltage-current measurements. Thin films chemical composition and morphology have been characterized with FTIR spectroscopy, atomic force microscopy (AFM) and contact angle measurements. A strong dependency of deposit character from the HMDSO concentration has been found and then compared with the same dependency of a typical low pressure plasma enhanced chemical vapour deposition process.     

Chemical composition and bioactivity of Citrus medica L. cv. Diamante essential oil obtained by hydrodistillation, cold-pressing and supercritical carbon dioxide extraction

The chemical composition of the essential oil of Citrus medica L. cv. Diamante peel obtained by hydrodistillation, cold-pressing and supercritical carbon dioxide extraction techniques was determined by GC/MS analysis. Forty-six components were fully characterised. Limonene and γ-terpinene were the major components of the oils obtained by hydrodistillation (HD) and cold-pressing (CP), while citropten was the major constituent in the oil obtained by supercritical carbon dioxide extraction (SFE). Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities were evaluated. The essential oil obtained by hydrodistillation exerted the highest inhibitory activity against BChE (IC?? value of 154.6 μg mL?1) and AChE (IC?? value of 171.3 μg mL?1. Interestingly, the oil obtained by cold-pressing exhibited a selective inhibitory activity against AChE. The essential oils have also been evaluated for the inhibition of NO production in LPS induced RAW 264.7 macrophages. The oil obtained by hydrodistillation exerted a significant inhibition of NO production with an IC?? value of 17 μg mL?1 (IC?? of positive control 53 μg mL?1).     

Mechanisms of peroxidic oxygen transfer to organic substrates : Oxidation of organic sulphides by chromium(vi)oxide diperoxide

The oxidation of organic sulphides (n-Bu₂S, PhSCH₃, Tolyl-SCH₃, p-Cl-C₆H₄SCH₃, and Ph₂S by (HMPT)CrO(O₂)₂1′ in CHCl₃ has been studied. The reaction produces the corresponding sulphoxides in nearly quantitative yields according to a 2:1 stoichiometry of sulphide to metaldiperoxide. A second-order-overall (order one in each of the reagents) kinetic law is obeyed. In parallel, the oxidation of organic sulphides by (HMPT)MoO(O₂)₂1' has been studied. Kinetic data, the observed rate laws, and the effect of inhibitors (HMPT, DABCO) have pointed out that-although 1' is significantly more reactive than 1′—considerable similarity exists between the two metaldiperoxides, in that both appear to act as electrophilic oxidizers. Also, through ¹H, ³¹P and ¹³C NMR investigations have permitted to assess the relevance of equilibria (HMPT)MO(O₂₂ MO(O₂)₂ + HMPT [with M = Mo(VI) or Cr(VI)]in solution, whereas no NMR evidence could be found for significant substrate coordination under the given conditions.