Measurement of natural radioactivity and radiation hazards for some natural and artificial building materials available in Romania

As building materials are known to be the second source regarding high radon concentrations, it is very important to determine the amounts of natural radionuclides from every building material in use. In the present study the most frequently used Romanian natural (sand, gypsum, limestone) and artificial (portland cement, lime, clinker, electrofilter powder, fly ash, cement-lime plaster mortar, cement plaster mortar) building materials were analyzed. The absorbed dose rate and the annual effective dose equivalent rate for people living in dwelling buildings made of these building materials under investigation were also calculated. The analysis was performed with gamma-ray spectrometry, with two hyper-pure germanium detectors. The activity concentrations of natural radionuclides were in the ranges: 5.2–511.8 Bq kg^?1 for ²²⁶Ra; 0.6–92.6 Bq kg^?1 for ²³²Th and <1–1,720.7 Bq kg^?1 for ⁴⁰K, respectively. The radium equivalent activity in the fifty-one (51) samples varied from 9 to 603 Bq kg^?1. By calculating all the radioactivity indices (Ra_eq, H _ext, I _α, I _yr) it was found that all the building materials under investigation can be used to erect dwelling buildings. Except for sample SA6, SA7 and SA11 among the natural building materials and sample SG1, SG2, FAH1, CLM1, CM1 among the artificial building materials that are considered hazardous materials when are used in large quantities.     

Characteristics of formvar films used to prevent alpha-detector contamination

Alpha spectrometry is an extremely useful and sensitive for detection of alpha-emitting nuclides. Contamination of the silicon detectors for low-level alpha spectrometry by recoil nuclides is a serious problem in the measurement of alpha emitters decaying to daughter nuclides with short half-lives. This unwanted contamination leads to decreased measurement sensitivity causing a degradation of the limit of detection. The simplest method to prevent this radioactive contamination of detector is to use a catcher film between the alpha source and the detector. In this work we describe the obtaining of the thin formvar films as stopper foils for recoil nuclei and we investigated the influence of these films on alpha spectrometry parameters, as energy shift (~30 keV) and resolution (~7%). No significant deterioration of the alpha spectrometry parameters was observed when using thin formvar films. Using the ASTAR web databases, which calculate stopping powers for alpha particles, the thickness of formvar films was estimated to be about 5.355 × 10⁻⁵ g/cm². The measurements were performed with an ORTEC SOLOIST alpha spectrometer with PIPS detector.     

Use of Chènevotte,a Valuable Co-Product of Industrial Hemp Fiber,as Adsorbent for Pollutant Removal. Part I: Chemical,Microscopic, Spectroscopic and Thermogravimetric Characterization of Raw and Modified Samples

FINEAU (2021–2024) is a trans-disciplinary research project involving French, Serbian, Italian, Portuguese and Romanian colleagues, a French agricultural cooperative and two surface-treatment industries, intending to propose chènevotte, a co-product of the hemp industry, as an adsorbent for the removal of pollutants from polycontaminated wastewater. The first objective of FINEAU was to prepare and characterize chènevotte-based materials. In this study, the impact of water washing and treatments (KOH, Na₂CO₃ and H₃PO₄) on the composition and structure of chènevotte (also called hemp shives) was evaluated using chemical analysis, X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, X-ray computed nanotomography (nano-CT), attenuated total reflectance–Fourier transform infrared (ATR-FTIR) spectroscopy, solid state NMR spectroscopy and thermogravimetric analysis. The results showed that all these techniques are complementary and useful to characterize the structure and morphology of the samples. Before any chemical treatment, the presence of impurities with a compact unfibrillated structure on the surfaces of chènevotte samples was found. Data indicated an increase in the crystallinity index and significant changes in the chemical composition of each sample after treatment as well as in surface morphology and roughness. The most significant changes were observed in alkaline-treated samples, especially those treated with KOH.     

Reactivity of 4‐thiothymidine with Fenton reagent investigated by UV‐visible spectroscopy and electrospray ionization mass spectrometry

The reactivity of the sulfur‐containing nucleoside 4‐thio‐(2′‐deoxy)‐thymidine usually abbreviated as 4‐thio‐thymidine, (S⁴‐TdR) under Fenton conditions, ie, in the presence of H₂O₂ and catalytic amounts of Fe(II), was investigated by UV‐vis spectroscopy and electrospray ionization single and tandem mass spectrometry (ESI‐MS and MS/MS). S⁴‐TdR hydroxylated on the S atom was found to be a key reaction intermediate, ultimately leading to (2′‐deoxy)‐thymidine usually abbreviated as thymidine, (TdR) as the main reaction product. This finding was in accordance with the outcome of the reaction between S⁴‐TdR and H₂O₂, previously investigated in our laboratory. On the other hand, the additional presence of ?OH radicals, induced by the Fe(II)/H₂O₂ combination, led to the increased generation of another interesting S⁴‐TdR product, already observed after its reaction with H₂O₂ alone, ie, the covalent dimer including a S? S bridge between two S⁴‐TdR molecules. More importantly, multihydroxylated derivatives of S⁴‐TdR and TdR were detected as peculiar products obtained under Fenton conditions. Among them, a product bearing an OH group both on the methyl group linked to the thymine ring and on the C5 atom of the ring was found to prevail. The results obtained during this study, integrated by those found previously in our laboratory, indicate 4‐thiothymidine as a promising molecular probe for the recognition, through a careful characterization of its reaction products, of the prevailing species among reactive oxygen species (ROS) corresponding to singlet‐state oxygen, hydrogen peroxide, and hydroxylic radical.     

Spectroscopic and electrochemical study of Rose Bengal in aqueous solutions of cyclodextrins

The interaction of Rose Bengal (RB) in aqueous solution of LiClO4 0.1 M with alpha-cyclodextrin (alpha-CD), hydroxypropyl-beta-cyclodextrins (HP-beta-CD) and hydroxypropyl-gamma-cyclodextrins (HP-gamma-CD) were studied by spectrophotometric measurements. The presence of Induced Circular Signals and the results of the analysis of the modifications in the absorbance spectra of RB produced by the presence of CDs in solution indicate that RB forms inclusion complexes only with HP-beta-CD and with HP-gamma-CD.     

Quantifying self-organization with optimal predictors

Despite broad interest in self-organizing systems, there are few quantitative, experimentally applicable criteria for self-organization. The existing criteria all give counter-intuitive results for important cases. In this Letter, we propose a new criterion, namely, an internally generated increase in the statistical complexity, the amount of information required for optimal prediction of the system's dynamics. We precisely define this complexity for spatially extended dynamical systems, using the probabilistic ideas of mutual information and minimal sufficient statistics. This leads to a general method for predicting such systems and a simple algorithm for estimating statistical complexity. The results of applying this algorithm to a class of models of excitable media (cyclic cellular automata) strongly support our proposal.     

Cyclodextrin/chlorophyll a complexes as supramolecular photosensitizers

The interactions between chlorophyll a, and three cyclodextrins, hydroxypropyl-beta-cyclodextrin heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin and hydroxypropyl-gamma-cyclodextrin, were studied in aqueous solutions by means of absorption, emission and circular dichroism spectroscopy. Nanosecond laser flash photolysis and steady-state singlet oxygen generation experiments were performed to clarify the photoactivity of chlorophyll a in these systems. Moreover the photosensitizing activity of these complexes towards human leukemia T-lymphocytes (Jurkat cells) was tested and compared with that of the free sensitizer, chlorophyll a. The results obtained indicate that each cyclodextrin is able to carry the pigment in monomeric form inside of cells producing singlet oxygen.     

Synthesis and characterization of perfluorinated arylenevinylene polymers

Fully fluorinated arylenevinylene polymers have been synthesized via a methodology based on the Stille cross‐coupling reaction and characterized by FTIR spectroscopy and MALDI‐TOF mass spectrometry. Investigation of thin film properties by cyclic voltammetry and ellipsometry shows that complete substitution of hydrogen atoms with fluorine atoms on the conjugated backbone of the poly(arylenevinylene)s results in a strong increase of the band gap. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 285–291, 2010     

Radon measurement in carbonated water with the Lucas cell and charcoal adsorption methods

There have been developed several different methods for measuring radon concentration in water which are now widely used, such as: liquid scintillation counting, Lucas cell counting, gamma and alpha spectroscopy. However, as far as the radon measurements in carbonated water are concerned, there are some issues caused by the gas excess. The aim of our work was to develop a simple method for measuring radon concentration in carbonated water that can be used for in situ measurements. Nevertheless, we propose not one, but two methods for measuring radon concentration in carbonated water. Thus, the first one is based on Lucas scintillation cells, and can be used for on-site measurements, while the second one utilizes activated charcoal adsorption, and needs a setup laboratory for gamma spectrometry measurements. For the evaluation of the methods, we compared the results of the Lucas cell-Luk3C method and of the activated charcoal method, both for non-carbonated and carbonated water. The simplest method for radon concentration determination—Lucas cell method—was successfully applied to fourteen natural carbonated water samples from Borsec to Bilbor area. The radon concentrations obtained ranged from 5.6 ± 0.5 to 39.6 ± 4.0 Bq/L, with a mean of 15.9 ± 2.6 Bq/L, these values are lower than 100 Bq/L, the maximum value recommended by the World Health Organization.     

Random poly(fluorenylene‐vinylene)s containing 3,7‐Dibenzothiophene‐5,5‐dioxide units: Synthesis,photophysical, and electroluminescence properties

The synthesis of new random poly(arylene‐vinylene)s containing the electron withdrawing 3,7‐dibenzothiophene‐5,5‐dioxide unit was achieved by the Suzuki–Heck cascade polymerization reaction. The properties of poly[9,9‐bis(2‐ethylhexyl)‐2,7‐fluorenylene‐vinylene‐co‐3,7‐dibenzothiophene‐5,5‐dioxide‐vinylene] (50/50 mol/mol, P1 ) and poly[1,4‐bis(2‐ethylhexyloxy)‐2,5‐phenylene‐vinylene‐co‐3,7‐dibenzothiophene‐5,5‐dioxide‐vinylene] (50/50 mol/mol, P2 ) were compared with those of terpolymers obtained by combining the fluorene, dibenzothiophene, and 1,4‐bis(2‐ethylexyloxy)benzene in 20/40/40 ( P3 ), 50/25/25 ( P4 ), and 80/10/10 ( P5 ) molar ratios. The polymers were characterized by ¹H NMR and IR, whereas their thermal properties were investigated by TGA and DSC. Polymers P1–5 are blue–green emitters in solution (λ_em between 481 and 521 nm) whereas a profound red shift observed in the solid state is emission (λ_em from 578 to 608 nm) that can be attributed both to the charge transfer stabilization exerted by the polar medium and to intermolecular interactions occurring in the solid state. Cyclic voltammetry permitted the evaluation of the ionization potentials and also revealed a quasi‐reversible behavior in the reduction scans for the polymers ( P1–4 ) containing the higher amounts of 3,7‐dibenzothiophene‐5,5‐dioxide units. Electroluminescent devices with both ITO/PEDOT‐PSS/ P1–5 /Ca/Al (Type I) and ITO/PEDOT‐PSS/ P1–5 /Alq₃/Ca/Al (Type II) configuration were fabricated showing a yellow to yellow–green emission. In the case of P4 , a luminance of 1835 cd/m² and an efficiency of 0.25 cd/A at 14 V were obtained for the Type II devices. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2093–2104, 2009