Radon measurements in water samples from the thermal springs of Yalova basin, Turkey

The radon concentration has been measured in thermal waters used for medical therapy and drinking purposes in Yalova basin, Turkey. Radon activity measurements in water samples were performed using RAD 7 radon detector equipped with RAD H₂O (radon in water) accessory and following a protocol proposed by the manufacturer. The results show that the concentration of ²²²Rn in thermal waters ranges from 0.21 to 5.82 Bql^?1 with an average value of 2.4 Bql^?1. In addition to radon concentration, physicochemical parameters of water such as temperature (T), electrical conductivity, pH and redox potential (E_h) were also measured. The annual effective doses from radon in water due to its ingestion and inhalation were also estimated. The annual effective doses range from 0.2 to 0.75 μSvy^?1 for ingestion of radon in water and from 2.44 to 9 μSvy^?1 for inhalation of radon released from the water.     

In situ study of diffusion and interaction of water and electrolyte solution in polyacrylonitrile (PAN) membrane using FTIR and two-dimensional correlation analysis

In the study, the diffusion process of water and CaCl₂ aqueous solution in polyacrylonitrile (PAN) membrane have been investigated using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and two-dimensional (2D) correlation analysis. In 2D ATR-FTIR spectra, the water ν(OH) band in PAN membrane during both water and CaCl₂ solution diffusion is split into three separate bands. However, the OH band appearing from bound water which forms hydrogen-bonding of CaCl₂ solution diffusion has a considerably lower wavenumber than that of pure water diffusion, which is due to association between Ca²⁺ ions and the CN groups in PAN. The sequential orders of the intensity changes for water and CaCl₂ solution diffusion in the region of ν(OH) and ν(CN) bands reveal the diffusion process and interaction of water and electrolyte in PAN membrane. That is, in the process of water diffusion in PAN membrane, water molecules first interact with –CN group in PAN to form weak hydrogen bond, then the moderate hydrogen-bonding interactions start gradually, and finally, the strong hydrogen-bonding interactions may be formed. When CaCl₂ solution diffuses in PAN membrane, the CN groups in PAN first associate with Ca²⁺ ions and then interact with water molecules to form hydrogen bond that grows gradually from weak to strong. Furthermore, the results are validated further by band fitting to calculate the ratio of each component band area and the proportion of component band to ν(OH) water band.     

A case study on the effect of water from groundwater sources on indoor radon levels

Indoor airborne radon concentration released from water was estimated over several months based on experimental measurements. When heated water including radon was used, the radon level became high in the entire house. Filling the bathtub with hot water had a strong effect on the indoor radon level. In winter, the indoor radon concentration was high due to windows being closed. The radon transfer coefficient was estimated 2.5·10⁻⁴ in this test house. This is 2.5 times higher than the average radon transfer efficiency estimated by UNSCEAR.     

Influence of transitional metal ions on lyotropic liquid crystals of hydroxyethyl cellulose acetate in N,N-dimethylformamide

The influence of inorganic salts on the formation of lyotropic liquid crystals of hydroxyethyl cellulose acetate (HECA) in N,N′dimethylformamide (DMF) was studied. In the presence of CaCl₂, an inorganic salt of a principal group metal, the solution of HECA/DMF/CaCl₂ was a biphasic system. The temperature of the transformation from the liquid crystalline phase to the isotropic one increased with adding CaCl₂ because local HECA concentration increases in the HECA/DMF phase. When CuCl₂ or CoCl₂, inorganic salts of transitional metals, was added, the solutions were monophasic systems and the complexes of HECA with Cu²⁺ or Co²⁺ were formed in solutions, which results in the increase of the temperature of the transfomation from the liquid crystalline phase to the isotropic one.     

Thermoelasticity of weak polyelectrolyte networks

The thermoelastic behavior of poly(vinyl alcohol)–poly(acrylic acid) networks was evaluated in pure water and CaCl₂ solution. The ratio f_e/f of the energy component of the force to the total force, evaluated without taking into account polymer–diluent specific interactions, ranged from ?0.75 for networks swollen in pure water to ?5.7 in 0.1M CaCl₂. However, an analysis based on Flory's theory of polyelectrolyte gels yields f_e/f constant at ?1.32 when specific interactions are accounted for. In addition, the variation of In (r²)₀ with CaCl₂ concentration is 2000 times that with water. In neither pure water nor CaCl₂ solution can specific interactions be neglected.     

Raman spectra and O NMR study effects of CaCl2 and MgCl2 on water structure

With various concentrations of CaCl₂ and MgCl₂ aqueous solution below 1.0 mol/l, Raman spectra of water in the OH stretch region of 2500-4000 cm⁻¹ and ¹⁷O NMR chemical shift of water are measured and the Raman spectra are deconvoluted. Both Raman spectra and ¹⁷O NMR of water show that the effect of Ca²⁺ on water structure is stronger than that of Mg²⁺. CaCl₂ and MgCl₂ destroy four hydrogen bonded water structure, but promote median water cluster size.     

Solvation of Calcium–Phosphate Headgroup Complexes at the DPPC/Aqueous Interface

The effects of sodium (Na⁺) and calcium (Ca²⁺) cations on model zwitterionic dipalmitoylphosphatidylcholine (DPPC) monolayers spread on metal chloride salt solutions are investigated by means of vibrational sum frequency generation (VSFG) and heterodyne‐detected (HD)‐VSFG spectroscopy. VSFG and HD‐VSFG spectra in the OH stretching region reveal cation‐specific effects on the interfacial water′s H‐bonding network, knowledge of which has been limited to date. It is found that low‐concentrated Ca²⁺ more strongly perturbs interfacial water organization relative to highly concentrated Na⁺. At higher Ca²⁺ concentrations, the water H‐bonding network at the DPPC/CaCl₂ interface reorganizes and the resulting spectrum closely follows that of the bare air/CaCl₂ interface up to ～3400 cm^?1. Most interesting is the appearance of a negative band at ～3450 cm^?1 in the DPPC/CaCl₂ Im χ_s⁽²⁾ spectra, likely arising from an asymmetric solvation of Ca²⁺–phosphate headgroup complexes. This gives rise to an electric field that orients the net OH transition moments of a subset of OH dipoles toward the bulk solution.     

Determination of air-loop volume and radon partition coefficient for measuring radon in water sample

A simple method for the direct determination of the air-loop volume in a RAD7 system as well as the radon partition coefficient was developed allowing for an accurate measurement of the radon activity in any type of water. The air-loop volume may be measured directly using an external radon source and an empty bottle with a precisely measured volume. The partition coefficient and activity of radon in the water sample may then be determined via the RAD7 using the determined air-loop volume. Activity ratios instead of absolute activities were used to measure the air-loop volume and the radon partition coefficient. In order to verify this approach, we measured the radon partition coefficient in deionized water in the temperature range of 10–30 °C and compared the values to those calculated from the well-known Weigel equation. The results were within 5 % variance throughout the temperature range. We also applied the approach for measurement of the radon partition coefficient in synthetic saline water (0–75 ppt salinity) as well as tap water. The radon activity of the tap water sample was determined by this method as well as the standard RAD-H₂O and BigBottle RAD-H₂O. The results have shown good agreement between this method and the standard methods.     

Cellulose wet wiper sheets prepared with cationic polymer and carboxymethyl cellulose using a papermaking technique

Carboxymethyl cellulose (CMC)-rich cellulose sheets were prepared with a cationic retention aid, poly[N,N,N-trimethyl-N-(2-methacryloxyethyl)ammonium chloride] (PTMMAC), using a papermaking technique. When 5% PTMMAC and 5% CMC were added to cellulose slurries, approximately 94% of the polymers were retained in the sheets by formation of polyion complexes between the two polymers. When the PTMMAC/CMC/cellulose sheets were soaked in solutions consisting of ethanol, water and calcium chloride (EtOH/H₂O/CaCl₂) with a weight ratio of 75:24:1, almost all PTMMAC and CMC molecules remained in the sheets, forming the structures of PTMMAC-N⁺Cl⁻ and CMC-COO⁻Ca²⁺Cl⁻ without dissolution of these molecules in the soaking solution. Thus, PTMMAC, CMC and calcium contents in the sheets were able to be determined on the basis of these PTMMAC and CMC structures from analytical data such as nitrogen, calcium and chlorine contents. The trade-off properties between sufficient wet strength in use and water-disintegrability after use can be added to the PTMMAC/CMC/cellulose sheets by selecting weight ratios of the EtOH/H₂O/CaCl₂ solution used as the impregnation liquid.     

The daily radon dose in body organs caused by drinking milk and water

Milk is considered as the richest nutrition, being used by people. When drinking milk or water the radon gas will transfer from air to them rapidly. Since milk is majorly composed of water, probably radon existence in livestock consumable water could be the main cause of its presence in milk. Different portion of milk changed by radon gamma ray and consumption of radon included water or milk has its effects on the human body. For investigation the effect of radon in water or milk on human organs, this study has been done in two phases with MCNPX software. In the first phase, the dose rate of absorbed gamma ray by different portion of milk which is indoctrinated by 1 Bq/m³ of radon during a day is calculated. Moreover, the effects shown by milk and its components in radon gamma spectrum, which is demonstrator of milk absorption spectrum, are also surveyed. In the second phase as well, according to the human body phantom, the absorbed gamma dose caused by daily consumption of indoctrinated water or milk with 1 Bq/m³ radon is calculated. The production rate of free radicals in milk and its different components are derived according to escape data of MCNPX code.     

CaCl2·6H2O/Expanded graphite composite as form-stable phase change materials for thermal energy storage

In this study, CaCl₂·6H₂O/expanded graphite (EG) composite was prepared as a novel form-stable composite phase change material (PCM) through vacuum impregnation method. CaCl₂·6H₂O used as the PCM was dispersed by surfactant and then, was absorbed into the porous structure of the EG. The surfactant was used to enhance the bonding energy between CaCl₂·6H₂O and EG, which fulfilled the composites with good sealing performance and limited the leakage of the inside CaCl₂·6H₂O. Differential scanning calorimetry and thermal gravimetric analysis show that all the composite PCMs possess good thermal energy storage behavior and thermal stability. Thermal conductivity measurement displays that the conductivities of the samples have been significantly improved due to the highly thermal conductive EG. The thermal conductivity of the sample including 50 mass% CaCl₂·6H₂O (8.796 W m^?1 K^?1) is 14 times as that of pure CaCl₂·6H₂O (0.596 W m^?1 K^?1). Therefore, the obtained composite PCMs are promising for thermal energy storage applications.     

Optically active diamide as a model for studying interactions between mineral salts and nylon type polyamides in methanol solutions

N,N′-Dicaproyl (–)1,2-diaminopropane (I) was used as a convenient model for the study of the optical activity of a nylon type polyamide: polysebacamide (–)1,2-diaminopropane (II). ORD of I was measured in different solvents. A peculiar behavior is observed in methanol in the presence of mineral salts. The influence of 0.1M potassium salts (Cl^?, Br^?, SCN^?, NO₃^?, SO₄^?2) and 0.1M alkaline chlorides and alkaline earth chloride hexahydrates on the optical activity of I in methanol are described. Alkaline salts and MgCl₂ give approximately the same effect: there is a decrease of the rotations without change of sign. SrCl₂ and CaCl₂ shift ORD curves towards the negative rotations, the last one giving complete inversion. This inversion is directly related to the CaCl₂ concentration and is attributed to adduct formation between amide groups and salt. Assuming that the different species are at equilibrium, an apparent equilibrium constant is obtained from the optical rotations for a complex of one mole of CaCl₂ with one mole of I. Results are used to discuss the complex ORD of poly(?) 1,2-diaminopropane sebacamide in methanol saturated with CaCl₂.     

Enhanced indoor radon concentration by using radon-rich well water in a Japanese wooden house in Fukuoka, Japan

Summary Radon measurements were carried out in a Japanese wooden house built on granitic geology, where radon-rich well water is used. Atmospheric radon concentrations were measured over one year with passive integrated radon monitors. The monitors were distributed at several locations in the house and were replaced every two months. In order to confirm the diurnal variation and heterogeneous distribution of radon, short-term measurements were carried out accordingly. Radon, its decay products and terrestrial gamma-radiations were measured in this survey. From the long-term measurement, the radon concentration in the house ranged from 14 to 184 Bq^. m^-3with an arithmetic mean of 45 Bq^. m^-3. A radon concentration of 184 Bq^. m^-3was observed in the bathroom in spring (March-May) though the radon level was normal in the living room and bedroom. In order to characterize the house, similar measurements were conducted in several surrounding houses. There was a significant difference in radon concentration between the investigated houses. There was a spatial distribution of the radon concentration and the highest value was found in the bathroom. Radon and its decay products concentrations varied with time, which increased from midnight to morning whereas they decreased during daytime. Although the radon concentration in tap water was 1 Bq^. l^-1, a high level of 353 Bq^. l^-1was found in the well water.While well water was being used, the indoor radon concentration near the bathroom increased rapidly with a maximum value of 964 Bq^. m^-3. It is clear that the use of well water enhanced the radon level around the bathroom.     

Ultrastructural and Intracellular Chemical Changes of a Novel Halophilic Strain V430 of <Emphasis Type="Italic">Staphylococcus saprophyticus</Emphasis> under CaCl<Subscript>2</Subscript> Stress

Observation of the ultrastructural and intracellular chemical changes of CaCl₂-tolerant strains is important both for understanding their adaptation mechanism under high salt stress and for providing theoretical basis of their application in treating high-CaCl₂ wastewaters. A novel strain V 430 isolated by us has been successfully used to decrease the chemical oxygen demand (COD) concentration of diosgenin wastewater from 20 g l⁻¹ to less than 0.5 g l⁻¹. For this study, strain V430 was incubated in culture media of different CaCl₂ concentrations (up to 9.0%). Strain V430 cells incubated in media of high CaCl₂ concentration excreted extracellular substances and accumulated intracellular Ca²⁺ and K⁺ and free amino acids. The levels of intracellular cations and free amino acids increased with increase in CaCl₂ concentration of the medium. The increase in total free amino acids was mostly due to accumulation of glutamic acid. The strain cells under 9.0% CaCl₂ stress took up K⁺ in a short time, while accumulation of Ca²⁺ proceeded over the whole growth process.     

An experimental study of the stability of TiO2 particles in organic–water mixtures

The stability of TiO₂ (Anatase) particles in various organic-water mixtures is examined experimentally. The results obtained reveal that the addition of AlCl₃ to a methanol–water dispersion leads to charge reversal on particle surface. If the concentration of methanol is high, CaCl₂ also leads to charge reversal, but NaCl does not have this effect. This implies that if the concentration of methanol is low, the coagulation between TiO₂ particles is due to double-layer compression for Na⁺ and Ca²⁺, and due to charge adsorption and neutralization for Al³⁺. A methanol dispersion is unstable without the addition of electrolyte, and the addition of both CaCl₂ and AlCl₃ has the effect of stabilizing the dispersion; the addition of NaCl does not have this effect. The qualitative behaviors of an acetone–water dispersion are similar to those of a methanol–water dispersion. It is interesting to observe, however, that the absolute mobility of a pure acetone dispersion has a maximum as the concentrations of both CaCl₂ and AlCl₃ vary, but charge reversal does not occur. Among the dispersions without the addition of electrolyte, a 50% organic–water mixture is most stable. Also, a methanol–water dispersion is more stable than an acetone–water dispersion, which can be explained based on the degree of dissociation of an electrolyte.     

Optimisation of the analytical detection of EDTA by HPLC in natural waters

Reversed-phase ion-pair liquid chromatography is often used to analyse traces of EDTA in natural water samples. Some perturbations due to the presence of major anions in samples, which can compete for ion pair formation with the Fe-EDTA complex used for the detection, have been observed but never estimated and quantified. A new operational method for determining EDTA in natural water samples is proposed by taking into account anion interactions. Qualitative and quantitative analyses of EDTA were performed with a synthetic water at various ionic strengths. From the effect of the ionic strength controlled by CaCl₂, the concentration of the counter-ion tetrabutylammonium bromide (TBA⁺Br^–) and the methanol of the mobile phase, optimal analytical conditions were proposed for a better determination of EDTA concentration. The limit of detection without preconcentration and the reproducibility defined as relative standard deviation were 5 μg/L and 3.6% (n = 12), respectively. This method was applied to natural samples.     

Determination of metal impurities in ultrapure CaCl2 and MgCl2 by ICP OES

An effective, rapid and simple analytical method for the determination of Na, K, Ca, Mg, Cd, Pb, Ba, Fe, Mn, Sr, Zr, Cu, Zn and Al at mg kg⁻¹ levels in the ultrapure salts MgCl₂ and CaCl₂ using optical emission spectrometry was developed. Optimisation of the operation conditions was performed with real samples of ultrapure MgCl₂ and CaCl₂. The results of the determination with multi-elemental water standards were compared to the internal standardisation, the standard addition method, and the maximum allowable content of the above mentioned elements in pure chemicals. The method was shown to be very sensitive with the following limits of detection: Na 1.01, K 3.12, Ca 0.263, Mg 0.275, Cd 0.0832, Pb 0.482, Ba 0.0153, Fe 0.0528, Mn 0.0473, Sr 0.0203, Zr 0.638, Cu 0.0732, Zn 0.0686 and Al 0.459 (all in mg kg⁻¹). The method exhibited satisfactory precision, high analytical recoveries, linear responses of an accuracy of at least 4 orders of magnitude and low contamination susceptibility.     

Towards ultra-responsive biodegradable polysaccharide humidity sensors

Sodium alginate is a biodegradable natural polymer that is derived from algae and is water soluble. Upon immersion in a CaCl₂ solution, a sodium alginate water solution is cross-linked to form water-insoluble calcium alginate. When the sodium alginate water solution is immersed in the CaCl₂ bath via a syringe pump, calcium alginate fibers are produced. By changing the CaCl₂ concentration, calcium alginate fibers with different degrees of cross-linking can be produced. Such fibers were found to differ in mechanical and morphological properties, and more interestingly, were found to possess humidity sensing and conductive properties. Interestingly, the higher the CaCl₂ concentration, the lower the degree of cross-linking, which produced softer fibers with better humidity sensing and conductive properties. The fibers were able to trap water in their structures, and a higher water content increased the conductivity due to the presence of an electrolyte salt in the fiber and due to the polyelectrolyte nature of the fiber itself. The cross-linking and percent shrinking degree, morphology and mechanical properties of the fibers were found to create significant changes in the conductivity and humidity sensing properties of the fibers. High humidity environments led to an increase in the conductivity of the fibers, whereas dry environments led to a decrease in the conductivity. The fibers, especially those with the highest CaCl₂ concentration, were determined to be ultra-responsive to humidity changes and exhibited very good repetition in humidity cycles. These tailored fibers are proposed as novel biodegradable conductive materials for various humidity sensing, robotic and bio-robotic applications.     

Application of ICP-QMS for the determination of ultratrace-levels of <Superscript>226</Superscript>Ra in geothermal water and sediment samples

A rapid, accurate and less labor intensive approach to determining ²²⁶Ra in environmental samples was examined; this utilized quadrupole-based inductively coupled plasma mass spectrometry (ICP-QMS). The procedure used chemical separation by ion exchange chromatography to remove most of the matrices after coprecipitation with BaSO₄. The average chemical recovery of the NIST SRM preparation method ranged from 60.5 to 85.9% using ¹³³Ba as internal tracer by gamma counting. This technique was capable of completing a ²²⁶Ra measurement within 3 min. It did not require an in-growth period to allow radon and its progeny to achieve secular equilibrium with the parent ²²⁶Ra as is needed for liquid scintillation analyzer (LSA). The method detection limits for the determination of ²²⁶Ra in geothermal water and sediment samples were 0.02 mBq L⁻¹ (0.558 fg L⁻¹) and 0.10 Bq kg⁻¹ (2.79 fg g⁻¹), respectively. The results obtained with various natural samples and the suitability of the method when applied to various environmental matrices such as geothermal water and sediment are discussed. When ICP-QMS was compared to double-focusing magnetic sector field inductively coupled plasma mass spectrometry (ICP-SFMS), good agreement was obtained with a correlation coefficient, r ² = 0.982.     

Fixation of actinide elements into zeolites/zeotypes and Flexcrete-cement matrix

The leaching behavior of -emitter radionuclides (uranium and americium) from zeolite-L and the zeotype (SAPO-34) in a Flexcrete-cement matrix were examined by static and dynamic methods using 0.005M CaCl₂ and synthetic ground water as leachants. The leaching rates of UO ₂ ²⁺ were found to be higher by about ten orders of magnitude than those of Am³⁺ for both zeolite-L and SAPO-34 in the cement matrix. The static and dynamic leaching rates of UO ₂ ²⁺ for SAPO-34 in CaCl₂ and synthetic ground water were ten orders of magnitude lower than those for L. SAPO-34 showed good selectivity for uranium at pH 2–3.5 and L was usefully selective for Am³⁺. Distribution coefficients of Am³⁺ and UO ₂ ²⁺ increased with equilibrium pH.