bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radiolytic degradation of methoxychlor in methanol and monitoring of radiolytic products by HPLC and GC-MS
Authors: Butt Shahid Bilal , Riaz Muhammad 
Published: May 2010

Abstract
Degradation of priority organic pollutant methoxychlor in methanol solution by gamma irradiation under varied experimental conditions has been optimized. The solution of methoxychlor was air saturated before irradiation. The extent of radiolytic degradation efficiency was monitored by reversed phase HPLC-UV; two major and two minor degradation products were detected. For 5 kGy gamma radiation dose at a rate of 200 kGy h−1≥95% methoxychlor was degraded. The degradation was also monitored by GC-ECD and the degradation products were identified using GC-MS after comparing their mass spectra with the NIST 98 m mass spectral library. It is proposed that major degradation occurs through dechlorination, dehydrochlorination, by the detachment of methoxyphenyl from methoxychlor and by interaction of other radicals generated by the methanol radiolysis. The probable reaction schemes for the formation of products have been proposed. Most of the generated products were methoxy substituted, probably due to the availability of the methoxy radical from methanol radiolysis. The identified radiolytic products of methoxychlor and the removal efficiency have been compared with those of UV photolysis. It is observed that although the source of degradation is somewhat different, the end products or radical generated species are of similar nature.
Rapid separation of lanthanides and actinides on small particle based reverse phase supports
Authors: Datta Arpita , Sivaraman N. , Srinivasan T. G. , Vasudeva Rao P. R. 
Published: May 2010

Abstract
This paper presents the results on the use of short columns (3−5 cm long) with small particle size (1.8 μm) for high performance liquid chromatographic separation of individual lanthanides and uranium from plutonium as well as uranium from thorium to achieve rapid separations i.e. separation time as short as 3.6 min for individual lanthanides, 1 min for thorium-uranium and 4.2 min for uranium from plutonium. These advantages can be exploited to significantly reduce analysis time, liquid waste generation as well as dose to operator when radioactive samples are analysed e.g. burn-up determination.
In the present work, a dynamic ion-exchange chromatographic separation technique was employed using camphor-10-sulfonic acid (CSA) as the ion-pairing reagent and α-hydroxy isobutyric acid (α-HIBA) as the complexing reagent for the isolation of individual lanthanides as well as the separation of uranium from thorium.
Uranium was separated from Pu(III) as well as Pu(IV) by reverse phase HPLC technique. The reverse phase HPLC was also investigated for the isolation and quantitative determination of uranium from thorium as well as lanthanide group from uranium.
The dynamic ion-exchange technique using small particle support was demonstrated for measuring the concentrations of lanthanide fission products such as La, Ce, Pr, Nd and Sm in the dissolver solution of fast reactor fuel. Similarly, the assay of uranium in the dissolver solution of fast reactor was carried out using reverse phase HPLC technique. The rapid separation technique using reverse phase HPLC was also demonstrated for separation of lanthanides as a group from uranium matrix; samples of LiCl-KCl eutectic salt containing chlorides of lanthanides in uranium matrix (typically 1:2000) were analysed.
Interactions of Sulfolobus acidocaldarius with uranium
Authors: Reitz Thomas , Merroun Mohamed , Rossberg Andre , Selenska-Pobell Sonja 
Published: May 2010

Abstract
Interactions of the acidothermophilic archaeon Sulfolobus acidocaldarius DSM 639 with U(VI) were studied by using a combination of batch experiments, X-ray absorption spectroscopy (XAS), and time-resolved laser-induced fluorescence spectroscopy (TRLFS). We demonstrated that at pH 2 this archaeal strain possesses a low tolerance to U(VI) and that its growth is limited to a uranium concentration below 1.1 mM. At similarly high acidic conditions (pH 1.5 and 3.0), covering the physiological pH growth optimum of S. acidocaldarius, at which U(VI) is soluble and highly toxic, rapid accumulation of the radionuclide by the cells of the strain occurred. About half of the uranium binding capacity was reached by the strain after an incubation of five minutes and nearly total saturation of the binding sites was achieved after 30 min. Both, EXAFS- and TRLF-spectroscopic analyses showed that the accumulated U(VI) was complexed mainly through organic phosphate groups. The EXAFS measurements revealed that U(VI) is coordinated to the organic phosphate ligands of the archaeal cells in a monodentate binding mode with an average U–P bond distance of 3.60±0.02 Å.
The influence of temperature on the diffusion of 125I− in Beishan Granite
Authors: Chen Tao , Sun Mao , Li Chun , Tian Wenyu , Liu Xiaoyu , Wang Luhua , Wang Xiangyun , Liu Chunli 
Published: May 2010

Abstract
China has planned to deal with the high-level radioactive wastes (HLW) in the middle of this century with deep geologic disposal method. The release of heat from HLW may cause the rise of temperatures in the surrounding backfilling materials or even the host rock of a repository. This brings about the concerns that the temperature elevation in the host rock may change the diffusion characteristics of key radionuclides and have some unpredictable effects in the performance assessment. In this paper, the influence of temperature on the diffusion of 125I− in Beishan Granite is studied by through diffusion method. The effective diffusion coefficients (D
e) of 125I− in the granite from 27 to 50 °C are obtained and analyzed as a function of temperature. Our result indicated that the relationship between D
e and temperature can be described by the modified Nernst equation, and the formation factors (F
f) of the granite from 27 to 50 °C is constant with an average value of 1.03×10−4.
Effect of humic acid, fulvic acid, pH, ionic strength and temperature on 63Ni(II) sorption to MnO2
Authors: Sheng Guodong , Hu Jun , Jing Han , Yang Shitong , Ren Xuemei , Li Jiaxing , Chen Yixue , Wang Xiangke 
Published: May 2010

Abstract
The effects of pH, ionic strength, temperature, humic acid (HA) and fulvic acid (FA) on the sorption of radionuclide 63Ni(II) to MnO2 have been investigated by using batch techniques. The results indicated that the sorption of 63Ni(II) on MnO2 is obviously dependent on pH values but independent of ionic strength. The presence of HA/FA strongly enhances the sorption of 63Ni(II) on MnO2 at low pH values, whereas reduces 63Ni(II) sorption at high pH values. The sorption of 63Ni(II) on MnO2 is attributed to inner-sphere surface complexation rather than outer-sphere surface complexation or ion exchange. The diffuse layer model (DLM) is used to simulate the experimental data well with the aid of FITEQL 3.2. The thermodynamic parameters (ΔH
0, ΔS
0, ΔG
0) are also calculated from the temperature dependent sorption isotherms, and the results suggest that the sorption of 63Ni(II) on MnO2 is a spontaneous and endothermic process.
Selective recovery of uranium from THOREX feed by hollow fibre supported liquid membrane technique containing di(2-ethylhexyl) isobutyramide (D2EHIBA) as the carrier
Authors: Pathak P. N. , Ansari S. A. , Prabhu D. R. , Kanekar A. S. , Mohapatra P. K. , Manchanda V. K. 
Published: May 2010

Abstract
Hollow fibre supported liquid membrane (HFSLM) studies were carried out for the selective recovery of uranium from THOREX feed solution (0.2 g/L U+200 g/L Th+0.03 M HF+0.1 M Al(NO3)3 at 4 M HNO3) using di(2-ethylhexyl) isobutyramide (D2EHIBA) as the carrier and distilled water as the strippant. About 85% of uranium was selectively transported into the receiver phase in 30 min with <1% contamination from thorium. On the other hand, under identical conditions of feed and strip solutions, about 90% of uranium was recovered in the same time when 5% TBP (tri-n-butyl phosphate) was used as the carrier, but a relatively large amount of thorium (>10%) was also co-transported to the product side. Strip phase acidity analysis revealed significant amount of acid co-transport with both the carriers. Acid transport was found to increase with the total salt content of the feed solution. The transport of metal ions was explained with the help of a theoretical model. Stability of the liquid membrane was also studied over about 5 d for long term reusability.
A Critical Evaluation of the Dynamical Thresholding Algorithm in Coupled Cluster Calculations
Authors: Auer Alexander A. 
Published: May 2010

Abstract
A new implementation of the Dynamical Thresholding (DT) coupled cluster doubles (CCD) approximation is presented. Using prescreening techniques for the intermediate quantities that occur in the CCD amplitude equations, a computationally efficient algorithm is obtained, in which one single threshold allows for control of accuracy. A critical evaluation of the accuracy and efficiency is carried out for two testcases. Furthermore, the issue of potential energy surface discontinuities and the usage of enveloping localized orbitals is discussed in detail.
Electron Structure Quantum Monte Carlo
Authors: Lüchow Arne , Petz Rene , Schwarz Annett 
Published: May 2010

Abstract
The diffusion quantum Monte Carlo method (DMC) is capable of calculating accurately the electronic energy for molecules and molecular aggregates. An overview is given on recent developments for the optimization of the guide function that determines the accuracy of the method. Furthermore, the versatility of DMC is shown with applications to Rydberg states, transition metal compounds, and weakly interacting systems.
Development of a Wavefunction-based Ab Initio Method for Metals Applying the Method of Increments
Authors: Voloshina Elena , Paulus Beate 
Published: May 2010

Abstract

Ab initio electron correlation calculations based on quantum-chemical methods are successfully applied to metallic systems via the method of increments, which is an expansion of the correlation energy in terms of one-body, two-body, and higher-order contributions from localized orbital groups. To deal with the two distinct problems that occur in metals, the difficulty of localization of the orbitals and the generation of clusters with neutral atoms in the center, we proposed an embedding scheme which has itself no metallic character but can mimic the metal in the internal region, where the atoms are correlated. The first application was made for solid mercury, where a very good agreement with experimental ground-state properties was achieved. Further the approach has been extended to other group 2 and 12 metals (Be, Mg, Zn, and Cd) where the metallic character is more pronounced than in mercury. Different variants of the embedding and the localized orbitals used for the incremental scheme have been developed and tested. Application of the method of increments to the investigated metallic systems allows us not only to obtain values close to experimental data but also to understand the influence of individual correlation-energy increments on cohesive properties and to clarify thereby some aspects of the structural features of the group 12 metals.
Self-interaction Free Relativistic Spin-density Functional Theory
Authors: Ködderitzsch D. , Ebert H. , Engel E. , Akai H. 
Published: May 2010

Abstract
We review the progress in the recent development of the relativistic optimized effective potential (ROEP) method within spin-density functional theory. The ROEP-equations for spin-polarized systems are derived and their application to open-shell atoms using the exact exchange approximation for the exchange correlation-functional is presented. Further, we expand the ROEP framework to treat extended systems within the KKR-multiple scattering formalism. We illustrate the application of the theory to open-shell free atoms and solids.
Discontinuities of the Chemical Potential in Reduced Density Matrix Functional Theory
Authors: Lathiotakis N. N. , Sharma S. , Helbig N. , Dewhurst J. K. , Marques M. A. L. , Eich F. , Baldsiefen T. , Zacarias A. , Gross E. K. U. 
Published: May 2010

Abstract
Using the discontinuity of the chemical potential as a function of excess charge, the fundamental gaps for finite systems and the band gaps of extended solids are determined within reduced density matrix functional theory. We also present the necessary and sufficient conditions for the one-body reduced density matrix of a system with fractional charge to be ensemble N-representable. The performance of most modern day reduced density matrix functionals is assessed for the gaps and the correlation energy of finite systems. Our results show that for finite systems the PNOF, BBC3, and power functionals yield very accurate correlation energies while for a correct description of the fundamental gap the removal of self-interaction terms is essential. For extended solids we find that the power functional captures the correct band gap behavior for conventional semiconductors as well as strongly correlated Mott insulators, where a gap is obtained in absence of any magnetic ordering.
Tensor Product Multiscale Many-Particle Spaces with Finite-Order Weights for the Electronic Schrödinger Equation
Authors: Griebel Michael , Hamaekers Jan 
Published: May 2010

Abstract
In this article we combine the favorable properties of efficient Gaussian type orbitals basis sets, which are applied with good success in conventional electronic structure methods, and tensor product multiscale bases, which provide guaranteed convergence rates and allow for adaptive resolution. To this end, we develop and study a new approach for the treatment of the electronic Schrödinger equation based on a modified adaptive sparse grid technique and a certain particle-wise decomposition with respect to one-particle functions obtained by a nonlinear rank-1 approximation. Here, we employ a multiscale Gaussian frame for the sparse grid spaces and we use Gaussian type orbitals to represent the rank-1 approximation. With this approach we are able to treat small atoms and molecules with up to six electrons.
Ab initio Electron Dynamics with the Multi-Configuration Time-Dependent Hartree-Fock Method
Authors: Nest Mathias , Klamroth Tillmann , Saalfrank Peter 
Published: May 2010

Abstract
This paper gives an overview of the theory and some selected applications of the Multi-Configuration Time-Dependent Hartree-Fock (MCTDHF) method. This method can be seen as an explicitly time-dependent version of the Complete Active Space Self-Consistent Field (CASSCF) method of standard quantum chemistry. Strengths and shortcomings are discussed, and some comparisons with other methods of correlated electron dynamics are given.
Local Time-Dependent Coupled Cluster Response for Properties of Excited States in Large Molecules
Authors: Kats Danylo , Schütz Martin 
Published: May 2010

Abstract
The new, Laplace transform based multi-state local CC2 response method is compared to the previous single-state approach. The new method employs adaptive state specific local approximations for the eigenvectors of the Jacobian. As a result, it is much less dependent on the initial un-truncated CCS wavefunction and able to locate the relevant eigenstates also in difficult cases where the initial CCS eigenvectors are qualitatively wrong and where the original single-state method failed. In this paper we compare excitation energies, transition strengths, and dipole moments of the individual local approaches and the canonical reference calculation, for a set of different molecules and excited states.
Exact Solutions for a Two-electron Quantum Dot Model in a Magnetic Field and Application to More Complex Sytems
Authors: Taut Manfred , Eschrig Helmut 
Published: May 2010

Abstract
We discussed exact solutions of the Schrödinger equation for a two-dimensional parabolic confinement potential in a homogeneous external magnetic field. It turns out that the two-electron system is exactly solvable in the sense, that the problem can be reduced to numerically solving one radial Schrödinger equation. For a denumerably infinite set of values of the effective oscillator frequency ω~ = √(ω
0
2+(ωc
/2)2) (where ω
0 is the frequency of the harmonic confinement potential and ωc
is the cyclotron frequency of the magnetic field) even analytical solutions can be given. Our solutions for three electrons are exact in the strong - and the weak correlation limit. For quantum dot lattices with Coulomb-correlations between the electrons exact solutions are given, provided the lattice constant is large compared with the dot diameters. We are investigating basic physical properties of these solutions like the formation and distortion of Wigner molecules, the dependence of the correlation strength from ω
0 and ωc
, and we show that in general there is no exact Kohn-Sham system for the semi-relativistic current density functional Theory.
Analytic Calculation of First-order Molecular Properties at the Explicitly-correlated Second-order Møller-Plesset Level
Authors: Höfener Sebastian , Hättig Christof , Klopper Wim 
Published: May 2010

Abstract
Formulae are derived and implemented for the analytic calculation of first-order molecular properties at the level of explicitly-correlated second-order Møller-Plesset perturbation theory. In this theory, which is denoted as MP2-F12 theory, Slater-type geminals are used to expand the first-order wave function. A second-order perturbation theory correction for single excitations into a complementary auxliary basis set is also included. At the MP2-F12 level, it seems sufficient to restrict the analytic calculation of energy derivatives to the level of standard approximation A of MP2-F12 theory and to assume the extended Brillouin condition to hold. Smooth and rapid convergence towards the basis-set limit is observed for the dipole moments of a selection of small closed- and open-shell molecules when calculated at the RI-MP2-F12/2A*[T+V] + CABS singles level in augmented correlation-consistent polarized valence double-, triple-, and quadruple-zeta basis sets that have been optimized especially for use in MP2-F12 theory.
Periodontal Ligament Fibroblasts Sustain Destructive Immune Modulators of Chronic Periodontitis
Authors: El‐Awady Ahmed R. , Messer Regina L.W. , Gamal Ahmed Y. , Sharawy Mohamed M. , Wenger Karl H. , Lapp Carol A. 
Published: May 2010

Background: In healthy periodontal tissue, innate immune responses effectively confine and suppress a bacterial insult. However, a disruption of the host–bacterial equilibrium may produce an overexpression of cytokines and lead to permanent, host‐mediated tissue damage. Although such periodontal destruction primarily results from activated immune mechanisms, the site‐specific damage suggests that local tissues participate in these pathologic changes. Periodontal ligament fibroblasts (PDLFs) are prominent in the periodontium and are critical in homeostasis and regeneration because they have the ability to produce multiple cytokines in response to a bacterial insult. These cells could play a role in the local pathogenesis of periodontal disease.Methods: We studied alkaline phosphatase (ALP) activity, interleukin (IL)‐6 production, and morphologic characteristics of cultured PDLFs that were isolated from periodontally healthy sites (H‐PDLFs) and diseased sites (D‐PDLFs) in humans. Quantitative analyses of 84 genes that are related to inflammation were performed using real‐time polymerase chain reaction arrays.Results: A mineralizing medium induced a significant increase of ALP in H‐PDLFs, but no significant enzymatic changes were detected in D‐PDLFs after such treatment. The protein and gene expression of IL6 showed a significant upregulation in D‐PDLFs, which also demonstrated a significant upregulation of 54% of genes in the inflammatory gene arrays.Conclusions: To our knowledge, these results represent the first biologic evidence that D‐PDLFs retain uniquely inflammatory phenotypes that could maintain localized destructive signals in periodontitis. The overexpression of proinflammatory cytokines by PDLFs could amplify local inflammation by the continuous triggering of immune responses. In addition, the location of these cells could be critical in the progression of the inflammatory front into the deeper tissues.
Association of Interleukin‐1 Receptor Antagonist Gene Polymorphisms With Generalized Aggressive Periodontitis in an Iranian Population
Authors: Baradaran‐Rahimi Hesam , Radvar Mehrdad , Arab Hamid R. , Tavakol‐Afshari Jalil , Ebadian Ahmad R. 
Published: May 2010

Background: Periodontitis is a multifactorial disease that occurs in the presence of bacteria, environmental factors, and genetic predispositions. It is suggested that polymorphisms in the interleukin‐1 (IL1) receptor antagonist gene have an important role in the susceptibility of the host to periodontitis. This study investigates the association of a variable number of tandem repeat polymorphism in the IL1RN gene with generalized aggressive periodontitis (GAgP).Methods: Sixty‐six subjects with GAgP and 56 periodontally healthy subjects took part in the study. All subjects were of Iranian Khorasanian (north‐east province of Iran) descent. Subjects were identified through clinical examinations and radiographs at the Mashad Dental School and Dental Research Center. DNA was extracted from peripheral blood cells, and different genotypes were detected using polymerase chain reaction amplification and fragment‐size analysis. Data were analyzed using the χ2 test.Results: The frequencies of the IL1RN genotype A1A2 (χ2 test; P = 0.001) and allele A2 (χ2 test; P = 0.006) were found to be significantly increased in patients with GAgP compared to normal subjects.Conclusion: These findings suggest that the polymorphic IL1RN gene is a risk determinant for generalized aggressive periodontitis in the Iranian Khorasanian population.
The SNARE Protein SNAP23 and the SNARE-Interacting Protein Munc18c in Human Skeletal Muscle Are Implicated in Insulin Resistance/Type 2 Diabetes
Authors: Boström Pontus , Andersson Linda , Vind Birgitte , Håversen Liliana , Rutberg Mikael , Wickström Ylva , Larsson Erik , Jansson Per-Anders , Svensson Maria K. , Brånemark Richard , Ling Charlotte , Beck-Nielsen Henning , Borén Jan , Højlund Kurt , Olofsson Sven-Olof 
Published: May 2010

OBJECTIVE
Our previous studies suggest that the SNARE protein synaptosomal-associated protein of 23 kDa (SNAP23) is involved in the link between increased lipid levels and insulin resistance in cardiomyocytes. The objective was to determine whether SNAP23 may also be involved in the known association between lipid accumulation in skeletal muscle and insulin resistance/type 2 diabetes in humans, as well as to identify a potential regulator of SNAP23.

RESEARCH DESIGN AND METHODS
We analyzed skeletal muscle biopsies from patients with type 2 diabetes and healthy, insulin-sensitive control subjects for expression (mRNA and protein) and intracellular localization (subcellular fractionation and immunohistochemistry) of SNAP23, and for expression of proteins known to interact with SNARE proteins. Insulin resistance was determined by a euglycemic hyperinsulinemic clamp. Potential mechanisms for regulation of SNAP23 were also investigated in the skeletal muscle cell line L6.

RESULTS
We showed increased SNAP23 levels in skeletal muscle from patients with type 2 diabetes compared with that from lean control subjects. Moreover, SNAP23 was redistributed from the plasma membrane to the microsomal/cytosolic compartment in the patients with the type 2 diabetes. Expression of the SNARE-interacting protein Munc18c was higher in skeletal muscle from patients with type 2 diabetes. Studies in L6 cells showed that Munc18c promoted the expression of SNAP23.

CONCLUSIONS
We have translated our previous in vitro results into humans by showing that there is a change in the distribution of SNAP23 to the interior of the cell in skeletal muscle from patients with type 2 diabetes. We also showed that Munc18c is a potential regulator of SNAP23.