Extension of the line element-less method to dynamic problems

Meccanica - The line element-less method is an efficient approach for the approximate solution of the Laplace or biharmonic equation on a general bidimensional domain. Introducing generalized...     

Random vibration mitigation of beams via tuned mass dampers with spring inertia effects

Meccanica - The dynamics of beams equipped with tuned mass dampers is of considerable interest in engineering applications. Here, the purpose is to introduce a comprehensive framework to address...     

Natural Product-Based Hybrids as Potential Candidates for the Treatment of Cancer: Focus on Curcumin and Resveratrol

One of the main current strategies for cancer treatment is represented by combination chemotherapy. More recently, this strategy shifted to the “hybrid strategy”, namely the designing of a new molecular entity containing two or more biologically active molecules and having superior features compared with the individual components. Moreover, the term “hybrid” has further extended to innovative drug delivery systems based on biocompatible nanomaterials and able to deliver one or more drugs to specific tissues or cells. At the same time, there is an increased interest in plant-derived polyphenols used as antitumoral drugs. The present review reports the most recent and intriguing research advances in the development of hybrids based on the polyphenols curcumin and resveratrol, which are known to act as multifunctional agents. We focused on two issues that are particularly interesting for the innovative chemical strategy involved in their development. On one hand, the pharmacophoric groups of these compounds have been used for the synthesis of new hybrid molecules. On the other hand, these polyphenols have been introduced into hybrid nanomaterials based on gold nanoparticles, which have many potential applications for both drug delivery and theranostics in chemotherapy.     

Induction of Mesomorphic Properties in Non-Mesogenic Octa(decyloxy) phthalocyanines

Abstract

As it is well known [1, 2], non-peripheral substituted octa (alkoxy)-phthalocyanines (Pc) do not exhibit neither thermotropic nor lyotropic mesomorphism (in binary mixtures with organic solvents). In this work we induced an enantiotropic mesophase due to charge-transfer (CT) interactions in mixtures of PC derivatives I-III (viscous or oil-like liquids) with a strong electron acceptor 2,4,7-trinitro-9-fluorenone (TNF). Decreasing of number and length of substituents and modification of chemical structure of phthalocyanine macrocycle by introduction of four sulfur atoms (compound IV) resulted in crystallinity of this compound. In contact preparation of IV with TNF a wide area of CT-complex showing the monotropic mesomorphic phase is found out. All above mentioned CT-complexes do not form any lyomesophases in binary mixtures with number of organic solvents.     

Online trapping and enrichment ultra performance liquid chromatography–tandem mass spectrometry method for sensitive measurement of “arginine-asymmetric dimethylarginine cycle” biomarkers in human exhaled breath condensate

Background

Exhaled breath condensate (EBC) is a biofluid collected non invasively that, enabling the measurement of several biomarkers, has proven useful in the study of airway inflammatory diseases, including asthma, COPD and cystic fibrosis. To the best of our knowledge, there is no previous report of any analytical method to detect ADMA in EBC.

Objectives

Aim of this work was to develop an online sample trapping and enrichment system, coupled with an UPLC–MS/MS method, for simultaneous quantification of seven metabolites related to “Arginine-ADMA cycle”, using the isotopic dilution.

Methods

Butylated EBC samples were trapped in an online cartridge, washed before and after each injection with cleanup solution to remove matrix components and switched inline into the high pressure analytical column. Multiple reaction monitoring in positive mode was used for analyte quantification by tandem mass spectrometry.

Results

Validation studies were performed in EBC to examine accuracy, precision and robustness of the method. For each compound, the calibration curves showed a coefficient of correlation (r²) greater than 0.992. Accuracy (%Bias) was <3% except for NMMA and H-Arg (<20%), intra- and inter-assay precision (expressed as CV%) were within ±20% and recovery ranged from 97.1 to 102.8% for all analytes.Inter-day variability analysis on 20 EBC of adult subjects did not demonstrate any significant variation of quantitative data for each metabolite. ADMA and SDMA mean concentrations (μmol L⁻¹), measured in EBC samples of asthmatic adolescents are significantly increased (p < 0.0001) than in normal controls (0.0040 ± 0.0021 vs. 0.0012 ± 0.0005 and 0.0020 ± 0.0015 vs. 0.0002 ± 0.0001, respectively), as well the ADMA/Tyr (0.34 ± 0.09 vs. 0.12 ± 0.02, p < 0.0001) and the SDMA/Tyr ratio (0.10 ± 0.04 vs. 0.015 ± 0.004, p < 0.0001).

Conclusions

The proposed method features simple specimen preparation, maintenance of an excellent peak shape of all metabolites and reduced matrix effects as well mass spectrometer noise. Moreover, the possibility to perform different cycles of enrichment, using large injection volumes, compensated for the low concentration of analytes contained in EBC, leading to a good analytical sensitivity. Preliminary data obtained from asthmatic and healthy adolescents, demonstrated that the analytical method applied to EBC seems suitable not only for research purposes, but also for clinical routinely analysis.     

Indoor radon levels and natural radioactivity in Turda salt mine, Romania

The purpose of the study is to evaluate the activity concentrations and distribution of natural radionuclides in Turda salt mine having in view the development on the future of the speleotherapy in this salt mine. The radon, gamma ray and gross alpha and beta radiation measurements have demonstrated the presence of low concentrations of natural radionuclides in rock salt and soil samples collected from different points of the salt mine and sustains the development of speleotherapy in this mine.     

The use of ultrasonic treatment for improvement of metrological performance of sorption atomic absorption determination of lead(II) and cadmium(II) traces

The optimal parameters for ultrasonic treatment (frequency 200–300 kHz, intensity 2–4 W cm^?2) were obtained to intensify Pb(II) and Cd(II) sorption concentration by carbon sorbent from apricot pit. The combined action of ultrasonic frequency of 18 kHz and 1 MHz on concentrate slurry increases its sedimentation stability from 3 to 180 minutes and decreases S_r value up to 7% at Pb(II), Cd(II) hybrid sorption atomic absorption determination in natural waters, brines, common salt.      

Evaluation of the radon concentration in Ocna Dej salt mine,Romania

Measurement of radon is of interest both for the health risk assessment and development of radon therapy in enclosed spaces like as caves, mines and spas. In Romania, radon therapy is not in use, yet. The development of this treatment method in mines from our country involves primarily, the evaluation of radon levels in the salt mines. In this paper, the results of radon gas measurement that were performed at Ocna Dej salt mine (Romania) are presented. The radon measurements were performed using two systems: radon monitor Pylon AB-5 system and CIS-P5M system. The average radon concentration was found to be between 9.14 ± 5.10 Bq/m³ and 31.70 ± 2.76 Bq/m³. These radon levels are lower in comparison to those reported for mines, caves or spas in other countries where radon therapy and speleotherapy is frequently in use. Radon concentration and environmental conditions from Ocna Dej salt mine are suitable for therapeutic applications.     

Assessment of calibration parameters for gamma-ray spectrometry systems

The Gamma-ray spectrometers are complex instruments and the quality of the data they provide depends strongly on their proper calibration. This paper describes the energy and efficacy calibration of two gamma-ray spectrometers in order to validate the method for measuring the activity of gamma-ray emitting radionuclides. The punctiform standard sources ⁶⁰Co, ¹³³Ba, ¹³⁷Cs and ²⁴¹Am were used in this study. Minimum Detectable Activity, Peak to Compton Ratio and the peak shape parameters were determinate. An inter-comparison of the results obtained with both systems was done. The results demonstrated that the activity values are comparable with low errors respecting with those for conventionally true activities.