The effect of a carbon-carbon double bond on electron beam-generated plasma decomposition of trichloroethylene and 1,1,1-trichloroethane

The effect of a carbon-carbon double bond on the energy required for decomposition in an electron beam-generated plasma reactor is studied by comparing the decomposition of trichloroethylene and 1,1,1-trichloroethane. A reaction mechanism for TCE decomposition based on a chlorine radical chain reaction is presented which accounts for the formation of all of the experimentally observed reaction products. TCE decomposition is autocatalyzed by reaction products, whereas TCA decomposition is inhibited. The rate expression for the decomposition of TCE in the reactor is determined to be r=−[T](15.07[T₀]^−0.40+0.006{[T₀]−[T]}), where [T] and [T₀] are both in ppm, and r is in ppm Mrad⁻¹. The energy expense ɛ for TCE decomposition is determined as a function of inlet concentration. For 99% decomposition of 100 ppm TCE in air, ɛ=28 eV/molecule, and ɛ=2.5 eV/molecule at 3000 ppm. This is only 2.5–5% of the amount of energy required to decompose a similar amount of TCA as reported by the authors in a previous study. By comparing the energy requirements for TCE decomposition to those for TCA decomposition, the TCE reaction chain length is determined to increase from approximately 20 at 100 ppm initial TCE concentration, to 40 at 3000 ppm. This work was supported by the Contaminant Plume Containment and Remediation Focus Area, Office of Environmental Management, U.S. Department of Energy.     

Etude des possibilites de dosage du lithium par activation au moyen de protons et de deutons de moyenne energie

The determination of lithium by measuring⁷Be, produced by proton or deuteron activation, has been studied. The extent of interference from boron or beryllium, which also form⁷Be, was measured. The calculated sensitivity limits when activating for one hour with 10μA beams of 14 MeV protons or 25 MeV deuterons are, for lithium, 1·10⁻¹ and 2.5·10⁻² ppm and for boron, 2·10⁻¹ and 1·10⁻¹ ppm, respectively.      

Radioactivity levels of <Superscript>238</Superscript>U and <Superscript>232</Superscript>Th,the α and β activities and associated dose rates from surface soil in Ulu Tiram,Malaysia

A survey was carried out to determine terrestrial gammaradiation dose rates, the concentration level of ²³⁸U and ²³²Th and α and β activities for the surface soil in Ulu Tiram, Malaysia A 125 measurements were performed using a NaI(T1) gamma-ray detector with crystal size of 1″ × 1″ on 15 soil samples collected from the site area about 102 km^{2 238}U and ²³²Th concentrations were determined in soils by using hyper pure germanium (HPGe) gamma-ray spectrometry. The activity of α and β from the surface soil was counted by using alpha beta counting system. The average value of ²³⁸U and ²³²Th concentrations in soil samples collected are 3.63±0.39 ppm within the range of 1.74±0.20 to 4.58±0.48 and 43.00±2.31 ppm within the range of 10.68±0.76 to 82 10±4.01 ppm, respectively. The average estimate of α and β activity in soil samples collected are 0.65±0.09 Bqg⁻¹ and 0.68±0.08 Bqg⁻¹, respectively. The average of terrestrial gamma-radiation dose rates measured in Ulu Tiram was found to be 200 nGy h⁻¹, within the range of 96 to 409 nGy h⁻¹. The population weighted outdoor annual effective dose was 1.2 mSv.     

Nafion-based solid-state gas sensors: Pt / Nafion electrodes prepared by an impregnation-reduction method in sensing oxygen

The influences of the reductant concentration of NaBH₄ and the quantity of Pt loading on the active surface area and the sensitivity of the Pt/Nafion electrodes prepared by an impregnation-reduction method in detecting oxygen were investigated in this study. The Pt/Nafion electrodes with a Pt loading of 4.99 mg/cm², obtained at 0.0107 M Pt(NH₃)₄Cl₂ and 0.06 M NaBH₄, show maximum sensitivities of 0.0528 A/ppm and 0.0538 A/ppm obtained in O₂ concentration regions of 0–5000 and 5000–50 000 ppm, respectively. A sensing model was also proposed to illustrate the sensing phenomenon. Received: 21 January 1998 / Accepted: 10 March 1998     

Nitrogen distribution measurements by neutron induced autoradiography

A method utilizing plastic track detectors was developed to determine the nitrogen distribution and concentration in the presence of boron in metals. Experiments were performed at the UVAR (cadmium ratio ≈25) and the NIST Reactor (cadmium ratio ≈3000). The minimum detectable concentration of nitrogen at a given concentration of boron has been estimated using the detector’s response to¹⁰B(n,α)⁷ Li reaction products in terms of track size distribution. The capability of the technique to detect nitrogen in the presence of boron has been demonstrated using 316L stainless steel with a nitrogen concentration of ≈560 ppm and a boron concentration of ≈0.86 ppm.     

Determination of oxygen with reactor neutrons

Oxygen in silicon was determined by the secondary nuclear reactions of⁶Li(n, α)T and¹⁶O(t, n)¹⁸F. Lithium fluoride was deposited in vacuum on fused quartz, covered with the sample and irradiated in a nuclear reactor. The depth profiles of¹⁸F in fused quartz and in silicon were observed, and enough depth to eliminate surface oxygen was estimated. On the basis of these results, oxygen was determined by the average cross-section method. Oxygen concentration in CZ silicon with various growing condition was 5–26 ppm and was consistent with those determined by the infrared absorption method. The detection limit of oxygen in silicon is 5 ppm.     

Boron in coral skeletons determined by prompt γ-ray analysis

A systematic and non-destructive technique is proposed for the determination of boron in coral samples by neutron-induced prompt γ-ray analysis (PGA) using a thermal neutron guide beam of the JRR-3M reactor. About 50–150 mg samples in sealed FEP film were irradiated and measured for 5000 s in the PGA system at a neutron flux of 2.4 × 10⁷ n cm⁻² s⁻¹. In order to determine B content in coral skeletons, the Doppler-broadened γ-ray peak of 478 keV (¹⁰B) was used together with the correction of interference from the Na-peak of 472 keV. The analytical precision was ~3% for the JCp-1 coral standard. The data (n = 56) obtained by the present method showed a range of B content from 40.7 to 76.9 ppm which is similar to reported values. Boron in corals showed the highest levels in Rukan-sho (Okinawa) with an average B content of 62.5 ppm, whereas corals collected from Mizugama (Okinawa), Cebu (the Philippines) and Khang Khao (Thailand) exhibited B contents of 56.5, 53.0 and 45.7 ppm, respectively. The uptake of boron by living corals may be influenced by seawater pH related to higher seawater B(OH)₄⁻. In this paper we discuss factors controlling the B levels in corals.     

Supramolecular interactions and structural transformations in the metal-organic sorbent-acetone nanoreactor system

By the ¹H NMR and Raman spectroscopy data it is shown that in the porous inclusion compound of Zn₂(C₈H₄O₄)₂[(N₂(CH₂)₆))]·n(CH₃)₂CO (n ≈ 0–4.7) acetone molecules exist in two structural forms: ketonic (CH₃)₂CO, for which the ¹H NMR chemical shift value is δ^ket = 0.8 ppm, and enolic CH₃C(O)=CH₂, for which δ^en(OH) = 11 ppm, δ^en(CH₂) = 8.9 ppm, and δ^en(CH₃) = 1.6 ppm are found, the average value over three proton sites being <δ^en> = 5.6 ppm. A sharp difference in chemical shift values for the keto and enol forms of acetone in the inclusion compounds can be assigned to the effect of structural chemical conditions in two types of adsorption centers.     

Effect of alteration processes on the distribution of radionuclides in uraniferous sedimentary rocks and their environmental impact, southwestern Sinai, Egypt

The contents of natural radionuclides in various types of sedimentary rocks in Um Bogma Formation and base of El Hashash Formation were determined by gamma-ray spectrometry. Three types of lower Carboniferous sedimentary rocks were investigated; sandstone (El Hashash Formation), dolostone and argillaceous sediments (Um Bogma Formation). The alteration processes are dolomitization, dedolomitization, karstification and lateritization. The specific radioactivity of ²³⁸U, ²²⁶Ra, ²³²Th and ⁴⁰K determined in different samples, indicate that ²³⁸U and its decay products contribute primarily to the high natural radioactivity of rocks. The maximum concentration of ²³⁸U reached up to 2129.36 ppm in argillaceous sediments. The average concentrations of determined radionuclides (²³⁸U, ²²⁶Ra, ²³²Th and ⁴⁰K) are 8.34 ppm, 7.88 ppm, 4.68 ppm and 0.3%, respectively in sandstone. In dolostones the average concentrations are 418.69 ppm, 808.75 ppm, 3.14 ppm and 0.29%, respectively. For argillaceous sediments are 276.88 ppm, 419.49 ppm, 11.47 ppm and 0.93%, respectively. The ²³⁸U/²²⁶Ra ratio in sandstone ranges between 0.89 and 1.25, while in dolostones and argillaceous sediments are 0.27–2.63 and 0.27–1.83, respectively. These variations in the concentrations of radioelements and their ratios are due to the action of the alteration processes affected these different sedimentary rocks in different times. Environmentally, the Ra_eq in dolostones and argillaceous sediments exceeds the permitted limits, while in the sandstone samples; it is within the permissible levels.     

Neutron activation analysis for osmium and ruthenium in platinum

A sensitive procedure for the simultaneous determination of trace levels of osmium and ruthenium in platinum, by thermal neutron activation analysis utilizing γ-ray spectrometry, was developed. The radiochemical separation method utilized perchloric acid for a selective oxidation of osmium and ruthenium to the volatile tetroxides. The distillation of the tetroxides greatly reduced the radiation hazard presented by the bulk of the activities in the matrix. Activities of 15-day¹⁹¹Os and 40-day¹⁰⁴Ru were measured by accumulation of pulses from a 3″ diameter NaI(Tl) crystal detector. Analyses of γ-ray spectra were achieved using digital computer techniques. The procedure provided analyses for a high purity platinum stock of 0.032±0.007 ppm Os and 0.044±0.005 ppm Ru. Work was performed at the Ames Laboratory of the U. S. Atomic Energy Commission, Contribution No. 3073.     

Neutron-activation analysis of vanadium in oils with californium-252

Results are given which have been obtained by the application of relatively small²⁵²Cf sources for the neutron-activation analysis of vanadium in oils. It could be shown that by optimization the geometrical conditions for activation and counting with a 24 μg²⁵²Cf source detection limits down to the order of 1 ppm vanadium are attainable; the absolute error, e.g., at 1.3 ppm is 0.32 ppm.     

Interference by neutron induced second order nuclear reaction in activation analysis of rare earths

In determining the trace impurities existing in high-purity rare earth samples by the neutron activation analysis, there are much interference due to nuclides induced from neutron induced second order nuclear reaction. This paper presents the degree of interference calculated over the ranges of irradiation time from 10⁵ to 10⁷ sec and of thermal-neutron flux from 1·10¹² to 1·10¹⁵ n·cm⁻²·sec⁻¹. According to the results of these calculations, degree of interference under the neutron irradiation condition for 288 hrs in the thermal-neutron flux of 3·10¹³n·cm⁻²·sec⁻¹ is concluded to be 6.4·10⁶ ppm Gd in Eu, 2.2·10⁴ ppm Sm in Eu, 1.9·10⁴ ppm Ho in Dy, 1.1·10³ ppm Eu in Sm, 1.1·10² ppm Ce in La and 1.1·10 ppm Tb in Gd, respectively. Especially, the Gd determination in the Eu target is extremely affected by¹⁵³Gd formed from the¹⁵¹Eu (n, γ) reaction. On the contrary, this reaction is effective in producing¹⁵³Gd activity.     

The determination of fluorine in bones by non-destructive neutron activation analysis using 11.2 sec20F

A fast non-destructive determination of fluorine in bone samples by thermal neutron activation analysis using¹⁹F(n, γ)²⁰F reaction was developed. About 0.1–1 g samples is irradiated for 15 sec in TRIGA MARK II reactor at a thermal neutron flux of 5·10¹¹ n·cm⁻²·sec⁻¹. After 15–25 sec cooling, the 1633 KeV²⁰F activity (T=11.2 sec) is counted for 15 sec with a Ge(Li) spectrometer. A standard sample is prepared by mixing CaF₂ and CaCO₃ powders. The interference from²³Na(n, α)²⁰F is corrected by employing²⁴Na 2754 KeV double escape peak activities in samples and the²⁰F/²⁴Na peak area ratio observed previously for pure Na₂CO₃ powder. The precision is 7% for a bone sample containing 1020 ppm F and the sensitivity is about 10 ppm F.     

Determination of chromium in blood by neutron activation analysis

A procedure for the determination of chromium in blood has been developed with a sensitivity of 5×10⁻³ μg Cr. Dried blood was irradiated with a neutron flux of 10¹² n·cm⁻²·sec⁻¹ in the VVRS reactor for 4 weeks, then the sample was mineralized and the chromium isolated by extraction as perchromic acid. The determination of the chromium content was accomplished by measuring the 0.32 MeV gamma energy of⁵¹Cr. In order to make correction for the interfering reaction⁵⁴Fe(n,α)⁵¹Cr, the formation of chromium from high-purity iron was investigated. The chromium content of the blood samples was between 1.03×10⁻² and 5.2×10⁻² ppm Cr.     

Effect of phenyl group on the structure and formation of transitional alumina from Al (OPh)<Subscript>3</Subscript>

The structure of freshly prepared Al(OPh)₃, its decomposition product, the hydrolyzed products and their structural evolution were investigated employing ²⁷Al MAS NMR spectroscopy, PXRD, TGA/DTA/DSC/FTIR techniques. In the ²⁷Al MAS NMR spectrum of the aluminium phenoxide, three signals with the chemical shift at 3.78, 21 and 45 ppm were observed. The chemical shift at 3.78 and 45 ppm revealed the presence of four and sixfold coordinated aluminum. The signal at 21 ppm corresponded to fivefold coordinated aluminium. When the aluminium phenoxide was directly decomposed in air at 600 °C, it resulted in amorphous product as evidenced from the PXRD pattern. The observed signals with chemical shifts at 10.1, 42, 73.6 ppm in the ²⁷Al MAS NMR spectrum indicated the presence of 6, 5 and 4 coordination for the aluminium atoms suggesting disordered transitional γ-alumina to be the product. The hydrolysis studies of Al(OPh)₃ with excess of water at 70 °C yielded bohemite (γ-AlOOH). The alumina obtained after dehydration at 600 °C was X-ray amorphous. The dehydrated product at 600 °C showed the presence of four and six coordinated aluminium atoms in the ²⁷Al MAS NMR spectrum confirming it to be ordered γ-Al₂O₃. Crystalline γ-Al₂O₃ was obtained on further heating at 800 °C.     

Spectral Accuracy and Sulfur Counting Capabilities of the LTQ-FT-ICR and the LTQ-Orbitrap XL for Small Molecule Analysis

Color Index Disperse Yellow 42 (DY42), a high-volume disperse dye for polyester, was used to compare the capabilities of the LTQ-Orbitrap XL and the LTQ-FT-ICR with respect to mass measurement accuracy (MMA), spectral accuracy, and sulfur counting. The results of this research will be used in the construction of a dye database for forensic purposes; the additional spectral information will increase the confidence in the identification of unknown dyes found in fibers at crime scenes. Initial LTQ-Orbitrap XL data showed MMAs greater than 3 ppm and poor spectral accuracy. Modification of several Orbitrap installation parameters (e.g., deflector voltage) resulted in a significant improvement of the data. The LTQ-FT-ICR and LTQ-Orbitrap XL (after installation parameters were modified) exhibited MMA ≤ 3 ppm, good spectral accuracy (χ² values for the isotopic distribution ≤ 2), and were correctly able to ascertain the number of sulfur atoms in the compound at all resolving powers investigated for AGC targets of 5.00 × 10⁵ and 1.00 × 10⁶.     

Substoichiometric isotope dilution analysis of iron in biological materials by the 8-quinolinol-extraction

A highly precise and accurate method for the determination of minor amounts of iron by substoichiometric isotope dilution analysis is described. The constant amount of Fe(III) is substoichiometrically extracted with 2·10⁻⁴M oxine in chloroform from the aqueous phase of pH 9.2–10.0 containing 6·10⁻³M tartrate. The interfering ions such as Mn(II), Co(II), Ni(II), Cu(II), and Zn(II), can be removed by the preliminary extraction of Fe(III) from 7.5M hydrochloric acid solutions into isopropyl ether. The present method has been applied to the determination of iron in biological standard reference materials, i.e., the NBS Spinach (SRM-1570) and the NIES Pepperbush (SRM No. 1), and the results obtained are 548±9 ppm (NBS certified value: 550±20 ppm) and 193±4 ppm, respectively.     

NMR Spectra of Cyclic Nitrones. 7. The Influence of Substituents and a Hydrogen Bond on <Superscript>14</Superscript>N and <Superscript>17</Superscript>O Chemical Shifts in Derivatives of 3-Imidoazoline 3-Oxide

Derivatives of 3-imidazoline 3-oxide have been studied by ¹⁴N and ¹⁷O NMR methods. Regularities of the influence of substituents and of a hydrogen bond on chemical shifts have been made apparent. The range of changes of the chemical shifts of the nitrogen and oxygen nuclei of the nitrone group has been determined. Both in the ¹⁷O and in the ¹⁴N NMR spectra the signals of the amino derivatives are the highest field signals for the nitrone group, and the lowest field signals are the signals of the cyano derivatives in the series of derivatives investigated. Depending on the substituent (from amino to cyano group) the ¹⁷O chemical shifts varied over a range ∼155 ppm, but the interval of change of the ¹⁴N chemical shifts for the same substituents was ∼110 ppm. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1336–1341. September, 2005.     

Genetic Engineering of Caulobacter crescentus for Removal of Cadmium from Water

Hexa-histidine (6His) peptide was inserted to a permissive site of the surface layer (S-layer) protein RsaA of Caulobacter crescentus. The recombinant strain JS4022/p723–6H, expressing RsaA-6His fusion protein was examined for its ability to sequester Cd(II) from the bacterial growth medium. When mixed with 1 ppm CdCl₂, JS4022/p723–6H removed 94.3 ∼ 99.9% of the Cd(II), whereas the control strain removed only 11.4 ∼ 37.0%, depending on experimental conditions. The effective contact time of the cells and Cd(II) was as short as 15 min. When higher concentrations of CdCl₂ were tested, JS4022/p723–6H consistently demonstrated enhanced binding capacity over the control strain. At 15 ppm of Cd(II), each gram of JS4022/p723–6H dry cells retrieved 16.0 mg of Cd(II), comparing to 11.6 mg g⁻¹ achieved by the control strain. This work provides a potential cost-effective solution toward bioremediation of heavy metals from aqueous systems.     

The use of the microtron for the activation analysis of pure metals and alloys

Oxygen and carbon concentrations up to 0.06 ppm and 0.03 ppm respectively were determined in high purity metals such as Fe, Cu, Nb, Mo, In and some others. Analytical procedures and results of the determination of alloying additives in a number of rare metal alloys are given. The relative standard deviation constitutes 0.02 to 0.04. Accuracy of the procedures used is confirmed by a comparison of experimental results with those of the other analytical methods. Experimental data on the sensitivity of determining 35 elements are reported on irradiating them with thermal neutrons and a bremsstahlung emitted by the microtron. For most elements (for radioactive isotopes having a half-life of above 2 min.) sensitivity of the analysis is 10⁻⁶ to 10⁻⁸, g, at the microtron current of 30 μA and irradiation time of less than 10 min.