Estimation of track registration efficiency in solution medium and study of gamma irradiation effects on the bulk-etch rate and the activation energy for bulk etching of CR-39 (DOP) solid state nuclear track detector

The fission track registration efficiency of diethylene glycol bis allyl carbonate (dioctyl phthalate doped) [CR-39 (DOP)] solid state nuclear track detector (SSNTD) in solution medium (K _wet) has been experimentally determined and is found to be (9.7 ± 0.5) × 10⁻⁴ cm. This is in good agreement with the values of other SSNTDs. The gamma irradiation effects in the dose range of 50.0–220.0 kGy on the bulk etch rate, V _b and the activation energy for bulk etching, E of this solid state nuclear track detector (SSNTD) have also been studied. It is observed that the bulk etch rates increase and the activation energies for bulk etching decrease with the increase in gamma dose. These results have been explained on the basis of scission of the detector due to gamma irradiation.     

Effect of gamma irradiation on the etching and optical properties of a newly developed nuclear track detector called (PNADAC) homopolymer

In the present work, we have determined the bulk-etch rates of a newly developed track detector called poly-[N-allyloxycarbonyl diethanolamine-bis allylcarbonate] (PNADAC) homopolymer at different temperatures to deduce its activation energy. The energy of activation is found to be (1.02±0.04) eV. This compares very well with the values of activation energy reported in the literature for the most commonly used nuclear track detectors. The effects of gamma irradiation on this new detector in the dose range of 4.7–14.5 Mrad have also been studied using UV–visible spectroscopic technique. The optical band gaps of the unirradiated and the gamma-irradiated detectors determined from the UV–visible spectra were found to decrease with the increase in gamma dose. These results have been explained on the basis of scission of the detector due to gamma irradiation.     

Evaluation of efficiency for in situ gamma spectrometer based upon cerium-doped lanthanum bromide detector dedicated for environmental radiation monitoring

Nuclear power plants that are planned to be constructed in various countries, including Poland, require to setup an environmental radiation monitoring system. Localization of the installation has to be preceded by the studies determining the level of natural background radiation. Presently the in situ gamma spectrometry is widely used for monitoring the natural as well as artificial radionuclides. An analysis and evaluation of parameters of the spectrometric system equipped with scintillation detector made of cerium-doped lanthanum bromide crystal are both the subject of the paper. The main question of the application of any gamma spectrometry system for the radiation monitoring purpose is how its efficiency looks like. Based on the numerical characteristics of the detector the absolute full energy peak efficiency was calculated. The three dimensions characteristics of gamma ray registration efficiency as the function of its energy and considered contaminated area diameter has been also performed. The study of numerical modeling based on MCNP code was performed by the ISOCS/LabSOCS software tool.     

Study of gamma irradiation effects on the etching and optical properties of CR-39 solid state nuclear track detector and its application to uranium assay in soil samples

The gamma irradiation effects in the dose range of 2.5?C43.0 Mrad on the etching and optical characteristics of CR-39 solid state nuclear track detector (SSNTD) have been studied by using etching and UV?CVisible spectroscopic techniques. From the measured bulk etch rates at different temperatures, the activation energies for bulk etching at different doses have also been determined. It is seen that the bulk etch rates increase and the activation energies for bulk etching decrease with the increase in gamma dose. The optical band gaps of the unirradiated and the gamma -irradiated detectors determined from the UV?CVisible spectra were found to decrease with the increase in gamma dose. These results have been explained on the basis of scission of the detector due to gamma irradiation. The present studies can be used for the estimation of gamma dose in the range of 2.5?C43.0 Mrad and can also be used for estimating track registration efficiency in the presence of gamma dose. The CR-39 detector has also been applied for the assay of uranium in some soil samples of Jammu city.     

Determination of rapeseed methyl ester oil volumetric properties in high pressure (0.1 to 350 MPa)

The isothermal compressibility coefficient, the bulk modulus, the cubic expansion coefficient, the density and the propagation speed of the pressure waves of rapeseed methyl ester oil (RMEO) are the thermophysical properties derived from the specific volume determined in this work and compared with the properties of diesel oil (DO). The temperature measurement interval ranges from 288.15 to 328.15 K and the pressure measurement interval from atmospheric pressure to 350 MPa. The experimental method used consisted of a volume change cell characterised by a linear variable differential transformer (LVDT) magnetic induction system adapted to a high-pressure vessel. To calculate the properties the modified Tait-Tammann equation was used and a high correlation coefficient was obtained with a 95% confidence level. The specific volume and compressibility coefficient were greater for DO than for RMEO; also, cubic expansion was greater for DO than for RMEO. These results pave the way for further practical application.     

Volume expansion and loss of sample due to initial self-heating in capillary electroseparation (CES) systems

Summary The application of a high voltage, V, in capillary electroseparations following sample injection, can cause loss of analyte if the rate of thermal expansion of the liquid in the capillary (due to ohmic heating) is more rapid than the rate of electro-migration of the slowest moving analyte into the column. We show that the limiting condition for avoidance of this undesirable effect requires that the ramp-up rate for the applied voltage is below a critical value. This critical (maximum) value is given to a good approximation by a simple formula (Eq. (30)). Limiting values of dV/dt are in the region of 1000 V s^–1 when the power loss in the capillary is around 3 W m^–1 (e.g. with a field of 30,000 V m^–1 and a current of 100 A). A detailed mathematical analysis which takes full account of the thermal dependence of key variables, indicates that thermal explosion will occur at fields above a critical value (Eq. (21)). We recommend that commercial CES instrumentation incorporates manual or software led ramp-up voltage control.     

Di- and trinuclear complexes with the mono- and dianion of 2,6-bis(phenylamino)pyridine: high-field displacement of chemical shifts due to the magnetic anisotropy of quadruple bonds

The monoanion of 2,6-bis(phenylamino)pyridine (HBPAP(-)) has been found to support quadruply bonded Cr(2)(4+) and Mo(2)(4+) units in Cr(2)(HBPAP)(4) (1) and Mo(2)(HBPAP)(4) (2). The corresponding dianion BPAP(2)(-) was able to stabilize the trinuclear complexes, (TBA)(2)Cr(3)(BPAP)(4) (3) and (TBA)(2)Ni(3)(BPAP)(4) (4), where TBA is the tetrabutylammonium cation. The dinuclear complexes have the typical paddlewheel configuration with Cr-Cr distances of about 1.87 A and a Mo-Mo distance of 2.0813(5) A and exhibit a high-field displacement of the corresponding N-H signals caused by the magnetic anisotropy of the quadruple bonds. For the trinuclear complexes, 3 has a linear chain of three chromium atoms arranged in an unsymmetrical fashion with two chromium atoms paired to give a quadruply bonded unit (Cr-Cr distance: 1.904(3) A) and an isolated, square planar Cr(II) unit at 2.589(3) A from the dimetal unit. On the other hand, the three nickel atoms in 4 are evenly spaced, having Ni.Ni distances of 2.3682(8) A. The trinuclear compounds show a twisted conformation with an overall torsion angle of about 30 degrees.     

Determination of copper(II) in a complex matrix after prereduction to copper(I) in a flow-injection system with an amperometric detector

A flow-injection system with a carbon paste detector is proposed for the determination of copper in complex media at +0.050 V vs. Ag/AgCl. Both the reduction current peak of Cu(II) and the oxidation peak of Cu(I) (obtained in the presence of hydroxylamine in the reagent stream) were proportional to the Cu(II) concentration in the original sample. The stabilization of Cu(I) in the hydroxylamine system provides a novel approach; the inherent repeatability of operation of flow-injection systems (timing, etc.) proved ideal for this utilization. Acidified Cu(II) samples containing additional metal ions [Fe(lI), Zn(II), Pb(II)] and relatively high concentrations of serum albumin were analysed. A chelating column retained heavy metal ions while allowing albumin to run to waste. The retained metals were subsequently eluted with nitric acid into a stream of sodium acetate or sodium acetate-hydroxyl- amine. Before reaching the detector, the pH of the sample plug was adjusted. With the hydroxylamine system, Fe(III) interference was minimized and the sensitivity and reproducibility were improved. The sample throughput was 25 h^?1. National Bureau of Standards Standard Reference Material 909 Human Serum was used to test the method.     

Validation of scanning electron microscope (SEM), energy dispersive X-ray (EDX) and gamma spectrometry to verify source nuclear material for safeguards purposes

Ten ore samples, two unpurified yellow cake samples and natural uranyl nitrate hexahydrate sample were analyzed by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray (EDX) method to verify source nuclear material. Samples represent source nuclear material as possible. All samples were scanned at ideal conditions; working distance = 10 mm, voltage = 30 kV, magnification value = × 100, spot size = 50 to screen samples for the presence of uranium and thorium, Also Hyper pure germanium (HPGe) gamma spectrometers were applied to estimate the uranium and thorium contents in Bq/kg (ppm). For the ore samples uranium-238 ranges from 1,049.23 Bq/kg (85.30 ppm) to 2,096.06 Bq/kg (170.41 ppm), uranium-235 ranges from 47.51 to 105.61 Bq/kg and thorium-232 ranges from 22.84 Bq/kg (5.65 ppm) to 41.78 Bq/kg (10.34 ppm). For the yellow cake samples and uranyl nitrate hexahydrate uranium-238 ranges from 42.99 Bq/kg (3.50 ppm) to 71,887.2 Bq/kg (5,844.49 ppm) and thorium-232 is 4.78 Bq/kg (1.83 ppm) and the other two samples are lower than the detection limit.     

Thin film of poly(bis[2-(methacryloyloxy)ethyl]phosphate) grafted on surface of poly(ether sulfone) membrane for plutonium(IV)-selective alpha tracks registration in CR-39 detector

Journal of Radioanalytical and Nuclear Chemistry - To impart chemical selectivity in the solid state nuclear track detector based quantification of Pu(IV) ions, a thin film of polymer of...     

Mechanism of the photolysis of substituted tetraphenylporphin with p-benzoquinones in vitro according to chemical nuclear polarization (CNP) data

It is established by means of chemical nuclear polarization that the photointeraction of quinones with porphyrin leads to the transfer of an electron with the formation of ion-radical pairs, and then to the transfer of a proton with the reversible reduction of quinone.     

Four different types of hydrogen bonds observed in 1,2-bis(N-benzenesulfonylamino)benzenes due to conformational properties of the sulfonamide moiety

The crystal structures of 1,2-bis(N-benzenesulfonylamino)benzenes with secondary and/or tertiary sulfonamide groups were determined by X-ray crystallographic analysis. Every Ar-sulfonamide group existed in synclinal conformation in the crystals even though it was secondary or tertiary. Each compound showed different types of hydrogen bonds in the crystal structure. 1,2-Bis(N-benzenesulfonylamino)benzene (1) formed two double hydrogen bonds connected to the next molecules, 1-(N-benzenesulfonylamino)-2-(N-benzenesulfonyl-N-methylamino)benzene (2) contained double hydrogen bond involved by both the sulfonamide moieties, 1,2-bis(N-4-toluenesulfonylamino)benzene (3) had both intra- and intermolecular hydrogen bonds, and 1-(N-methyl-N-4-toluenesulfonylamino)-2-(N-4-toluenesulfonylamino)benzene (4) had one double hydrogen bond involved by only one sulfonamide moiety. Sulfonamides 1 and 3 formed infinite arrays of the molecules, and sulfonamides 2 and 4 formed racemic dimer of their conformational enantiomers via the hydrogen bonds.     

Comparison of two calorimetric methods to determine the loss of organic matter in Galician soils (NW Spain) due to forest wildfires

Seven forest soils, Cambisols under pinus, located at Galicia (NW Spain) and affected by forest wildfires were collected to determine the loss of organic matter due to the effect of burning, using calorimetric methods. The enthalpy of combustion, ΔH, of the organic matter of the burnt and the corresponding unburnt soils was calculated from the thermograms obtained with a differential scanning calorimeter (DSC-7, Perkin-Elmer). From these data, the loss of organic matter during the fires was calculated. On the other hand, the organic matter content for each burnt and unburnt soil studied was determined by thermogravimetry (TG) and, in the same way, the loss of organic matter was obtained. High linear, significant correlations were found between the enthalpy of combustion of the soil organic matter (SOM) and the organic matter content measured by thermogravimetry. Consequently, comparison of the loss of organic matter obtained by both methods indicated that the quantitative results are similar. Both techniques allow to determine the degradation level of the soils affected by forest wildfires, taking the loss of organic matter during the fire as a degradation index.     

Flow potentiometric and constant-current stripping analysis for arsenic(V) without prior chemical reduction to arsenic(III): Application to the Determination of Total Arsenic in Seawater and Urine

Arsenic(V) is reduced to elemental arsenic on a gold-coated platinum-fibre electrode at electrolysis potentials below ?1.60 V vs. Ag/AgCl and subsequently re-oxidized, either by means of a constant current, or chemically, with gold(III) as oxidant. Total arsenic in acidified seawater can be determined by means of electrolysis for 60 s at ?1.80 V vs. Ag/AgCl and subsequent stripping in 4 M hydrochloric acid containing 2.5 M calcium chloride. The detection limit obtained after 60 s of electrolysis (ca. 0.1 μg1^?1) is about ten times lower than that obtained by the electrochemical stripping methods for arsenic(III) reported hitherto. Total arsenic in urine is determined after digestion with nitric acid and hydrogen peroxide.     

Enhancement of the power conversion efficiency for inverted polymer solar cells due to an embedded CuxO interlayer formed by using Cu(I) acetate and Cu(II) acetate

Structural, optical, and photovoltaic properties of copper-oxide (Cu_xO) thin films formed by using a sol–gel method were investigated. X-ray diffraction patterns showed that the Cu_xO films prepared utilizing Cu(I) acetate or Cu(II) acetate and annealed under ambient atmosphere at various temperatures were polycrystalline with two phases, Cu₂O and Cu₆₄O. Transmittance spectra showed that the energy band gaps of the Cu_xO thin films formed by using Cu(II) acetate were smaller than those formed by using Cu(I) acetate. Current–voltage results showed that the power conversion efficiencies of the inverted polymer solar cells utilizing the Cu_xO interlayer formed by using Cu(II) acetate were better than those utilizing the Cu_xO interlayer formed by using Cu(I) acetate due to the multiple band gaps of the Cu(II) acetate.     

Preliminary investigation into suitable techniques to measure the chemical yield of radionuclides in thermal neutron irradiated samples at AWE (Atomic Weapons Establishment)

Radiochemical separation methods are required for the accurate measurement of radionuclides in complex matrices. To be able to quantify the results after the separation of radionuclides, known amounts of either radioactive tracers or inactive carrier solutions are added at the start of the separation. The added isotopes/elements are then measured at the end of the analysis to calculate the chemical yield for the element or isotope. The chemical yield data is applied to the counting data of the analytes of interest to produce quantified results. Recently, changes have been made to the techniques used to measure chemical yields at the Atomic Weapons Establishment for samples containing fission products. Preliminary development work using wavelength dispersive X-ray fluorescence and inductively coupled plasma–atomic emission spectrometry is discussed, including a comparison of results and evaluation of measurement uncertainty. The use of the techniques to measure fission products in a thermal neutron irradiated uranium sample is described.     

Cobalt bis(dicarbollide) ions functionalized by CMPO-like groups attached to boron by short bonds; efficient extraction agents for separation of trivalent f-block elements from highly acidic nuclear waste

New boron substituted cobalta bis(dicarbollide)(1-) ion (1) derivatives of formula [(8,8′-(RPhP(O)(CH₂)nC(O)N) < (1,2-C₂B₉H₁₀)₂-3,3′-Co]⁻ (R = Ph or C₈H₁₇, n = 1, 3a, 3b; R = Ph, n = 2, 3c), [(8-(Ph₂P(O)CH₂C(O)NR)(1,2-C₂B₉H₁₀))(1′,2′-C₂B₉H₁₁)-3,3′-Co]⁻ (R = H, C₂H₅, CH₂C₆H₅, 5a-c) and [(8-(²RPhP(O)CH₂C(O)N(¹R)CH₂-1,2-C₂B₉H₁₀))(8′-CH₃O-1′,2′-C₂B₉H₁₀)-3,3′-Co]⁻ (¹R = Benzyl, ²R = Ph or C₈H₁₇, 7a,b) were prepared with the aim to develop a new class of efficient extraction agents for partitioning of polyvalent f-block elements, i.e. lanthanides and actinides from high-level activity nuclear waste. The anionic ligands were characterized by multinuclear NMR spectroscopy and MS, the structures of Cs3a and the calcium complex of 7a were determined by X-ray diffraction analysis. The crystallographic study of the Cs3a proved a formation of linear chains in the structure, where the metal cation is coordinated by oxygen atoms of the CMPO terminal groups. The X-ray structure of the Ca²⁺ complex of the ionic ligand 7a proved a 1:3 metal to ligand ratio. Presented also is the X-ray structure of the starting ammonium compound 6 used in the synthesis of 7a and 7b. With exception of 5c, these anionic ligands are of high extraction efficiency, the highest being found for 7a in low polar solvent mixture hexyl methyl ketone-dodecane 1:1. These properties qualify some of these derivatives for possible technological applications.     

Determination of eight nitrosamines in water at the ng L(-1) levels by liquid chromatography coupled to atmospheric pressure chemical ionization tandem mass spectrometry

In this work, we have developed a sensitive method for detection and quantification of eight N-nitrosamines, N-nitrosodimethylamine (NDMA), N-nitrosomorpholine (NMor), N-nitrosomethylethylamine (NMEA), N-nitrosopirrolidine (NPyr), N-nitrosodiethylamine (NDEA), N-nitrosopiperidine (NPip), N-nitroso-n-dipropylamine (NDPA) and N-nitrosodi-n-butylamine (NDBA) in drinking water. The method is based on liquid chromatography coupled to tandem mass spectrometry, using atmospheric pressure chemical ionization (APCI) in positive mode with a triple quadrupole analyzer (QqQ). The simultaneous acquisition of two MS/MS transitions in selected reaction monitoring mode (SRM) for each compound, together with the evaluation of their relative intensity, allowed the simultaneous quantification and reliable identification in water at ppt levels. Empirical formula of the product ions selected was confirmed by UHPLC-(Q)TOF MS accurate mass measurements from reference standards. Prior to LC-MS/MS QqQ analysis, a preconcentration step by off-line SPE using coconut charcoal EPA 521 cartridges (by passing 500 mL of water sample) was necessary to improve the sensitivity and to meet regulation requirements. For accurate quantification, two isotope labelled nitrosamines (NDMA-d(6) and NDPA-d(14)) were added as surrogate internal standards to the samples. The optimized method was validated at two concentration levels (10 and 100 ng L(-1)) in drinking water samples, obtaining satisfactory recoveries (between 90 and 120%) and precision (RSD<20%). Limits of detection were found to be in the range of 1-8 ng L(-1). The described methodology has been applied to different types of water samples: chlorinated from drinking water and wastewater treatment plants (DWTP and WWTP, respectively), wastewaters subjected to ozonation and tap waters.