The role of phosphate released from Na–Al–P glass under repository conditions in speciation and transport of americium

The uptake of natural radioactivity by pasture-grass collected from seven different grasslands of Digor was calculated. The activities of ²²⁶Ra, ²³²Th and ⁴⁰K in pasture-grass were in the range of 21.8 ± 6.3–49.6 ± 13.4, 51.9 ± 13.2–127.7 ± 23.8 and 309.5 ± 33.5–807.3 ± 64.4 Bq kg⁻¹, respectively. The soil to pasture-grass transfer factors were evaluated and determined to be in the range from 0.26 ± 0.13 to 0.69 ± 0.34, 0.64 ± 0.27 to 1.99 ± 0.40 and 0.64 ± 0.014 to 1.40 ± 0.032 for ²²⁶Ra, ²³²Th and ⁴⁰K, respectively. The distribution of ²²⁶Ra and ²³²Th in different parts of pasture-grass indicated a decreasing tendency in order of root > stem > leaf. ⁴⁰K mainly accumulated in stem of pasture-grass and is followed by declining trend stem > leaf > root.

     

Kinetic study on preparation of substoichiometric tungsten oxide WO2.72 via hydrogen reduction process

Controlling the conditions of the oxygen partial pressure and temperature to prepare the WO_2.72 (W₁₈O₄₉) via reduction was possible through thermodynamic consideration. WO_2.72 was synthesized via heating to 1073 K in 5% H₂–95% Ar mixture gas flow from ammonium tungstate which was prepared by hydrothermal process. With the reducing prolonging time, the products were changed from WO_2.72 to WO₂ and then metal W. Thermogravimetric (TG) analysis showed ammonium tungstate decomposed completely to WO₃ at 773 K. Isothermal reductions using TG analysis were carried out at 905 K, 925 K, 945 K and 973 K in 5% H₂–95% Ar mixture gas flow, respectively. The whole reduction from WO₃ to WO_2.72 divided into three parts: initial nucleation and growth stage, final interfacial reaction stage and intermediate stage, was controlled jointly by both mechanisms. Fitting results showed that the initial stage obey the one-dimensional Avrami–Erofeev equation, the apparent activation energy was 132.7 ± 1.1 kJ mol⁻¹ and the pre-exponent factor was 4.82 × 10⁵ min⁻¹; the final stage expressed by 2-dimensional interfacial reaction, the apparent activation energy was 144.0 ± 2.1 kJ mol⁻¹ and the pre-exponent factor was 3.20 × 10⁵ min⁻¹.

     

Newly selective electrochemical sensors for trace-level determination of Al(III) ions in drainage water,spiked tap water and pharmaceutical preparation samples

In this work, two newly sensitive and selective Al(III)-modified carbon paste electrodes (MCPEs) were developed based on diphenylcarbazone (DPC) modifier mixed with tricresyl phosphate plasticizer and either graphite powder (electrode I) or graphite powder mixed with graphene (electrode II). The potentiometric performance characteristics of the two electrodes were scrutinized and discussed. The proposed sensors showed a high electrochemical response in the linear concentration range of 1.0 × 10⁻⁶ to 1.0 × 10⁻² mol L⁻¹ with a good Nernstian slopes of 20.12 ± 0.30 mV decade⁻¹ and 20.63 ± 0.66 mV decade⁻¹ and limits of detection of 9.0 × 10⁻⁷ and 8.5 × 10⁻⁷ mol L⁻¹ for electrode (I) and electrode (II), respectively. Both electrodes showed a fast response time and reasonable thermal stability. The potentiometric response of the DPC-based electrodes was independent on the pH of the tested solutions in ranges of 2.5–5 and 2.5–5.5 for electrode (I) and electrode (II), respectively. The two electrodes can be also used in partially non-aqueous medium containing up to 20% (v/v) acetone or methanol with no significant changes in the working concentration ranges or the slopes. The proposed electrodes showed fairly good discriminating ability toward Al(III) ions in comparison with many other metal ions. The electrodes were applied successfully for Al(III) ions determination in drainage water, spiked tap water and pharmaceutical preparation samples. Furthermore, the electrode surfaces were characterized using energy-dispersive X-ray (EDX) and scanning electron microscopic (SEM) as surface characterization techniques and Fourier Transform Infrared (FT-IR) technique to confirm the interaction between Al(III) and DPC.

     

High-performance thin-layer chromatography method for the quantification of quetiapine fumarate and its related genotoxic impurities using green solvents

A novel high-performance thin-layer chromatographic (HPTLC) analytical method has been developed and optimized for the quantification of quetiapine fumarate (QF) and its two genotoxic impurities in drug substance and drug product. The desired separation was achieved on 60F₂₅₄ pre-coated HPTLC plates using combination of green solvents, ethyl acetate‒ethanol‒n-heptane (5:1:4, V/V) as developing solvents. The detection wavelength used for quantification was 229 nm. QF and its two related genotoxic impurities, namely, 2-chloroaniline and 2-aminodiphenylsulfide, were well resolved from one another with retention factor values of 0.13 ± 0.02, 0.57 ± 0.02 and 0.76 ± 0.02, respectively. The optimized method was validated according to the guidelines laid down by the International Council for Harmonisation. The linearity was determined in the range of 100–600 ng/spot for QF and 10‒60 ng/spot for its two related genotoxic impurities; R² ≥ 0.993. The method exhibited precision along with good accuracy, where 0.51, 0.86 and 1.86. The percentage recoveries obtained for 2-chloroaniline and 2-aminodiphenylsulfide were 99.04‒101.04%. The developed method can be successfully used for the analysis of drug samples.

     

Study of natural radionuclides in Karun river region

In this study the concentration of natural radionuclides has been investigated in soil and water of Karun river by using a high resolution (HPGe detector, n-type) γ-spectrometry. The concentrations range in water sample was 47.6 ± 5.6–130.8 ± 6.3, 0.0–23.4 ± 0.5 and 0–6.4 ± 2.0 Bq L⁻¹ for ⁴⁰K, ²³²Th and ²²⁶Ra respectively. For soil samples the concentration range of 275.7 ± 8.6–458.6 ± 6.8, 19.2 ± 5.35–41.1 ± 3.95 and 29.9 ± 1.53–50 ± 1.54 Bq kg⁻¹ was obtained respectively for ⁴⁰K, ²³²Th and ²³⁸U. ¹³⁷Cs was also detected in some part of the region in soil samples. The mean concentration of ¹³⁷Cs was 5.5 ± 0.6 Bq kg⁻¹. The origin of this activity is unknown. The average absorbed dose rate in outdoor air at a height of 1 m above the ground was found to be 54.3 ± 3.7 nGy h⁻¹. The results of this study indicate that the area has standard background radiation level.     

A combined LC-MS/MS and LC-MS3 multi-method for the quantification of iodothyronines in human blood serum

We report here a novel approach for the extraction and analysis of thyroid hormones (TH) and their metabolites (THM) from human serum samples. Our method features a compact, 96-well micro-titre plate-based pre-analytic extraction/clean-up workflow combined with an isotope dilution LC-MS/MS-MS³ analytical method. In particular, these features make possible the detection of iodothyronines at their endogenous concentrations in serum differing by a factor of ca. 10⁴, with potential to semi-automate the pre-analytics. The method was validated by the assessment of linearity, lower limits of quantification and detection (LLOQ and LLOD respectively), intra- and inter-day accuracy, precision, process efficiency (PE), matrix effect (ME) and relative recovery (RE). Calibration curves were linear in the concentration range in sample matrix from 0.1–250 nM for T₃, rT₃, T₄ and 3-T₁AM and from 0.005–1 nM for 3,5-T₂ and 3,3′-T₂. Using a 200-μL sample volume, the analyte dependant LLOQ were in the range 0.005 (3,5-T₂) to 0.25 (T₄) nM and LLOD were between 0.002 (3,5-T₂) and 0.052 nM (T₄). We applied the LC-MS/MS-MS³ method to the analysis of a cross section of patients with disorders of the thyroid hormone axis. T₄, T₃ and rT₃ concentrations (± standard deviation) were 120 ± 18, 1.9 ± 0.4 and 0.45 ± 0.09 nM respectively. 3,3′-T₂ concentrations (± standard deviation) were 0.079 ± 0.022 nM; 3,5-T₂ concentrations were below the LLOQ and/or LLOD in all but a single sample (0.013 nM). This method expands the analytical spectrum to endogenous thyroid hormone metabolites such as 3,5-T₂ which exert biological actions and rT₃ which may act as surrogate markers for disturbed thyroid hormone metabolism.

Graphical abstract

     

Investigation of isothermal and dynamic cure kinetics of epoxy resin/nadic methyl anhydride/dicyandiamide by differential scanning calorimetry (DSC)

Isothermal and dynamic differential scanning calorimetry (DSC) was exploited to study the curing behavior of diglycidyl ether bisphenol-A epoxy resin with various combining ratios of dicyandiamide (DICY) and nadic methyl anhydride (NMA). Curves of prepared samples indicated that the enthalpy of the reaction decreased with increasing the molar ratios (NMA/DICY) up to 40% after which an exothermic peak peculiar to the effect of anhydride appeared at a higher temperature. The curing behavior examination of the samples containing the aforementioned molar ratio of NMA/DICY (= 40%) was carried out using isothermal condition at different temperatures (130–145 °C) and dynamic condition DSC at various heating rates (2.5–20 °C min⁻¹). Under the isothermal condition, by constructing a master curve, the values of activation energy (E_a) and pre-exponential factor (A) were calculated 89.3 kJ mol⁻¹ and 1.2 × 10⁺⁹ s⁻¹, respectively. The activation energy of the curing reactions in a dynamic mode was obtained 85.32 kJ mol⁻¹ and 88.02 kJ mol⁻¹ using Kissinger and Ozawa methods, respectively. Likewise, pre-exponential factors were also calculated 3.35 × 10⁺⁸ and 7.4 × 10 ⁺⁸ s⁻¹, respectively. The overall order of reaction for both conditions was found to be a value around 3.

     

Densitometric high-performance thin-layer chromatography methods for the quantification of oleuropein in Olea europaea leaves and pharmaceutical preparation utilizing normal- and reversed-phase silica gel plates

Two validated, simple and precise densitometric high-performance thin-layer chromatography (HPTLC) quantification methods were proposed for both qualitative and quantitative estimation of oleuropein in Olea europaea leaves and a pharmaceutical product utilizing normal-phase and reversed-phase silica gel TLC plates. In method I, 10 × 20 cm glass plates coated with 0.2 mm thin layers of normal-phase silica gel 60 containing F₂₅₄ (E-Merck, Germany) and a mixture of ethyl acetate‒methanol‒water (8:1:0.5, V/V) were used as the stationary and the mobile phase, respectively. Method II utilized 10 × 20 cm glass-backed plates supporting 0.2 mm layers of RP-18 silica gel 60 containing F₂₅₄ (E-Merck, Germany) as the stationary phase and green solvents mixture composed of ethanol‒water (5.5:4.5, V/V) as the mobile phase. The two methods resulted in sharp, symmetrical, well-resolved peaks at R_F values of 0.47 ± 0.02 and 0.78 ± 0.03 with linearity ranges 200‒1400 ng/spot (r² = 0.9994) and 200‒1400 ng/spot (r² = 0.9996) for method I and method II, respectively. Spots corresponding to oleuropein were scanned at 200 nm. The two methods complied with the ICH guidelines for validation. Due to simplicity, low cost and short analysis time, the methods can be good alternatives for the quality control of different products containing olive leaves extract or pure oleuropein.

     

Mineralogical role on natural radioactivity content in the intertidal sands of Tamilnadu coast (HBRAs region), India

Activity concentration and mineralogical characterization in the intertidal sand samples of Tamilnadu coast, India have been analyzed. From the gamma spectral analysis, the average value of ²³⁸U, ²³²Th and ⁴⁰K in the intertidal sand samples are 12 ± 4, 59 ± 4 and 197 ± 26 Bq kg⁻¹ respectively. The average value of ²³²Th alone is slightly higher than the world average value. From XRD and FTIR analysis, monazite, zircon, ilmenite, magnetite, hematite, quartz, witherite, calcite, nacrite, microcline feldspar, orthoclase feldspar, gibbsite and organic carbon are identified. Of these minerals, monazite and microcline feldspar are the most associated with the presence of ²³²Th and ⁴⁰K respectively.

     

Sorption/desorption study of strontium on Ain Oussera soils around the Es-Salam reactor facility

Four types of undisturbed soils around the Es-Salam reactor (Algeria) were used to evaluate the sorption behavior of strontium. The batch study was carried out under different experimental conditions. The kinetics were well fited by pseudosecond order model. Soils’s activation energies were 12.37, 14.76, 15.5 and 16.17 kJ mol⁻¹, corresponding to ion-exchange-type sorption. Sorption was exothermic (ΔH° < 0), spontaneous (ΔG° < 0) and favorable at low temperature. Competing cations, particularly Ca²⁺ reduce the Sr adsorption. Desorption reaction showed a higher value of Sr in the easily extractible phase indicating a relative availability of the element.

     

Thermal and electrical properties of Ca5Mg4−xZnx(VO4)6 (0 ≤ x ≤ 4)

Calcium vanadates Ca₅Mg_4−xZn_x(VO₄)₆ (0 ≤ x ≤ 4) have been studied for the first time using a set of high-temperature methods of analysis. The onset of melting process determined from differential scanning calorimetry decreases from 1158 to 881 °C (± 1.5 °C) with increasing of x (dopant’s content). CTE temperature dependence is found to show a hysteresis. Electrical transport properties measured by impedance spectroscopy in air of different humidity are also discussed. The value of electrical conductivity does not depend on air humidity. It is found to equal to 1.5 × 10⁻⁶ S cm⁻¹ at 720 °C for Ca₅Mg₄(VO₄)₆ which is specific for garnet-related crystals.

     

Effect of the natural radioactivity concentrations and 226Ra/238U disequilibrium on cancer diseases in Penang,Malaysia

Natural radioactivity measurements and assessment of radiological hazards in soil and sand samples obtained from Penang, Malaysia were carried out using the Exploranium GR-135 Plus “Identifier” Radioisotope Identification Device and high-resolution High Purity Germanium (HPGe) detector system. The activity concentrations of ²³⁸U, ²²⁶Ra, ²³²Th, and ⁴⁰K were found to be 184±11, 396±22, 165±14, and 835±28 Bq kg^?1 respectively, and the external gamma dose rate is 315±44 nGy h^?1 for soil samples. For sand samples, the activity concentrations of ²³⁸U, ²²⁶Ra, ²³²Th and ⁴⁰K were 31±8, 62±16, 36±6, and 369±17 Bq kg^?1, respectively, and the external gamma dose rate is 66±12 nGy h^?1. To assess the radiological hazard of radioactivity present in the samples, the radium equivalent activity, annual effective dose, annual gonadal dose equivalent, external hazard, and internal indices were calculated.The Ra_eq values of soil samples were higher than the limit of 370 Bq kg^?1, which is equivalent to a gamma dose of 1.5 mSv yr^?1, whereas the Ra_eq for sand samples was lower than 370 Bq kg^?1. The calculated concentrations by HPGe spectroscopy were compared with the measured concentrations detected by a GR-135 spectrometer. The calculated and measured gamma dose rates had an ideal correlation coefficient R of 0.72. The gamma dose rates in Penang increased with the average annual age-standardized rates (ASR) for all cancers between 1994 and 2010. The effects of the pH value of soil and sand samples on natural radionuclides concentrations were investigated. The high concentration of ²²⁶Ra/²³⁸U ratio disequilibrium (²²⁶Ra/²³⁸U of 1.76–2.33) was observed in the sampling sites. Moreover, a portable continuous radon monitor (SNC, model 1029, Sun Nuclear Corporation) was used to measure the radon concentration of the soil surface. The radon concentrations were found to vary from 7 to 50 Bq m^?3. A positive correlation was observed between the radon and radium concentrations in samples measured by the SNC continuous radon monitor and HPGe detector.     

Studies on radionuclides around Hemavathi river basin of Karnataka,India

The activity concentration and total annual effective dose of the terrestrial naturally occurring radionuclides (²³²Th, ²²⁶Ra and ⁴⁰K) were measured in soil and rock samples collected from various locations of Hemavathi river basin in Karnataka, using HPGe detector. The results revealed that activity concentration of radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K in the soil had geometrical mean values of 16.7 ± 0.6, 33.9 ± 1.2 and 359.9 ± 9.2 Bq kg^?1, respectively. In rock samples activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K had geometrical mean values of 20.2 ± 0.7, 18.0 ± 0.9 and 276 ± 9.6 Bq kg^?1, respectively. The external Hazard index and indoor hazard index were found to be within safety limits prescribed by European commission 1999 report.     

Analyses of radionuclides in the Oued Awlitis 001 and Galb Inal lunar meteorites by HPGe gamma-ray spectrometry

Highly sensitive nondestructive HPGe gamma-ray spectrometry was used for the analysis of the cosmogenic (²⁶Al) and primordial (⁴⁰K, ²³⁸U, and ²³²Th) radionuclides in the Oued Awlitis 001 and Galb Inal lunar meteorites. The measured ²⁶Al activities were very different (84.0?±?4.8 dpm/kg vs. 8.4?±?1.2 dpm/kg, respectively), mainly because of different cosmic-ray exposure ages of the investigated meteorites. The pre-atmospheric radii were 5?±?1 cm and 11?±?2 cm, respectively, which would result in total pre-atmospheric masses in the range of 0.7–2.5 kg and 7–23 kg, respectively.

     

Distribution of activity concentration and dose rates in selected coastal areas on western and eastern Black Sea

Radioactivity measurements were performed, at the east (Georgia) and west (Romania) part of the Black Sea, for natural radionuclides and ¹³⁷Cs in collected water and sediment samples using lab-based and in situ gamma-ray spectrometry. The activity concentrations of ¹³⁷Cs at Georgian area in the sediment and seawater ranged between 20 to 50 Bq kg⁻¹ and 8 to 25 Bq m⁻³, respectively while at the Romanian area the activity concentration ranged from 10 to 30 Bq kg⁻¹ and 3 to 15 Bq m⁻³, respectively. The activity concentration values of ⁷Be at the Georgian area reached values up to (30 ± 4) Bq kg⁻¹. The induced dose rates to marine organisms in both areas estimated by the ERICA assessment tool were much lower than the screening value of 10 μGy h⁻¹.

     

The effects induced by proton irradiation on structural characteristics of nuclear graphite

A grade TSX graphite was irradiated by a 2.5 MeV proton and a dose of 1.47 × 10¹⁸ ion cm⁻² at 330 K. The displacement per atom under this irradiation condition was about 0.02. The lattice parameter, crystallite size and the vacancies density in the graphite was measured before and after irradiation. It was found that the proton irradiation led to an increase in the volume of the sample. The volume change in the irradiated sample was confirmed by atomic force and scanning electron microscopes observations as increased roughness and pore size. Also, FTIR results showed that graphite is slightly oxidized by irradiation.

     

Measurement of soil radioactivity levels and radiation hazard assessment in mid Rechna interfluvial region,Pakistan

Radioactivity levels in soil samples, collected from mid Rechna interfluvial region, Pakistan have been estimated by using gamma ray spectrometric technique. ²²⁶Ra, ²³²Th, the primordial radionuclide ⁴⁰K and the artificial radionuclide ¹³⁷Cs have been measured in the soil of the study area. The mean radioactivity levels of ²²⁶Ra, ²³²Th, ⁴⁰K and ¹³⁷Cs were found to be 49.0 ± 1.6, 62.4 ± 3.2, 670.6 ± 33.9 and 3.5 ± 0.4 Bq kg⁻¹ respectively. The mean radium equivalent activity (Ra_eq), outdoor radiation hazard index (H _out), indoor radiation hazard index (H _in) and terrestrial absorbed dose rate for the area under study were determined as 189.9 ± 8.8 Bq kg⁻¹, 0.51, 0.65 and 70.1 nGy h⁻¹ respectively. The annual effective dose to the public was estimated to be 0.43 mSv. The measured values are comparable with other global radioactivity measurements and are found to be safe for public and environment.     

Studies on radon concentration in drinking water around Hemavathi river basin,Karnataka State,India

Concentrations of radon in drinking water collected from 32 locations of Hemavathi river basin, Karnataka, India have been measured by emanometry method. The radon concentration in water ranged from 2.7 ± 0.1 to 138.5 ± 1.5 Bq l⁻¹ with a geometrical mean of 25.3 ± 1.1 Bq l⁻¹. The study revealed that about 82.35% of drinking water samples contained radon concentration more than 11.1 Bq l⁻¹, the limit is fixed by Environmental Protection Agency. Among the different parameters measured, concentration of radon showed weak correlation with chloride and no correlation with alkalinity, pH, nitrate, sulphate, fluoride and total dissolved substance.

     

Measurement of naturally occurring/fallout radioactive elements and assessment of annual effective dose in soil samples collected from four districts of the Punjab Province,Pakistan

Soil samples were collected from different localities of districts Jhelum, Chakwal, Rawalpindi and Attock, Punjab Province, Pakistan with an aim to measure naturally occurring radionuclides, namely ²²⁶Ra, ²³²Th, ⁴⁰K and fallout ¹³⁷Cs radionuclide using a P-type coaxial high purity germanium (HPGe) γ-ray spectrometer. Measured specific activities of ²²⁶Ra, ²³²Th and ⁴⁰K in these soil samples ranged from 26.02 ± 7.11 to 93.54 ± 8.13 Bq kg⁻¹, 29.34 ± 2.58 to 114.41 ± 2.80 Bq kg⁻¹ and 348.15 ± 3.20 to 752.98 ± 4.20 Bq kg⁻¹, respectively. Activity due to ¹³⁷Cs was observed in some locations which ranged from 0.4 ± 0.2 to 7.8 ± 0.3 Bq kg⁻¹. From the measured activity concentrations, radium equivalent activity concentrations were determined followed by calculations of mean absorbed dose rate and mean annual effective dose for the inhabitants of the studied area. The mean radium equivalent activity, internal and external hazard indices values came out to be 179.26 ± 11.93 Bq kg⁻¹, 0.64 ± 0.05 and 0.48 ± 0.03, respectively. Indoors and outdoor average annual effective dose values were found to be 0.42 ± 0.03 and 0.10 ± 0.01 mSv, respectively. Present data have been compared with the published data for other parts of the world and found to be safe for public and environment.     

Qualitative and quantitative analysis of arctiin and arctigenin in Arctium tomentosum Mill. by high-performance thin-layer chromatography

A sensitive, reliable and rapid high-performance thin-layer chromatography (HPTLC) method for the determination of arctiin and arctigenin in Arctium tomentosum Mill. was established. A. tomentosum Mill. extract was used for chromatographic analysis. The ratio of chloroform and methanol was 48:5 as mobile phase. Temperature is 20–23 °C and humidity is less than 30%. The scanning wavelength is 280 nm. The results showed that arctiin had a good linear relationship in the range of 0.5315–5.8465 μg, r = 0.9982; arctigenin had a good linear relationship in the range of 0.5654–6.2194 μg, r = 0.9951. Precision analysis showed that the RSD < 3.0%. The stability study showed that the sample was stable within 24 h at room temperature, RSD < 2.0%. The average recoveries were 103.07 ± 1.57% and 98.55 ± 2.71%, respectively. The antioxidant activity of Arctium tomentosum Mill. was also identified. The results showed that the antioxidant component identified by thin-layer chromatography–1, 1-diphenyl-2-trinitrophenylhydrazine (TLC-DPPH) was arctigenin not arctiin. The proposed HPTLC is a simple and accurate method for the qualitative and quantitative analysis of arctiin and arctigenin in Arctium tomentosum Mill. from different areas.