A new method for studying the transport of radon and thoron in various building materials using CR-39 and LR-115 solid state nuclear track detectors

Radon (²²²Rn) and thoron (²²⁰Rn) α-activities per unit volume were measured inside and outside different building materials by using two types of solid state nuclear track detectors (SSNTD) (CR-39 and LR-115 type II). In addition, the radon and thoron emanation coefficients of the studied materials were evaluated. Based on these data, the transport of radon and thoron across parallelepipedic blocks of the building materials could be investigated and radon and thoron global α-activities per unit volume outside different building material blocks were determined. Moreover, the diffusion length and the effective diffusion coefficient of radon in the building materials were evaluated and the total alpha activity due to radon in the atmospheres of different rooms consisting of different building materials was studied.     

Toxic effects of copper (II) ions on bovine hemoglobin

In this paper, the toxic influence of copper ions (II) on bovine hemoglobin was investigated by the combination of ultraviolet-visible absorption, fluorescence, time-resolved fluorescence, synchronous fluorescence, and circular dichroism spectra. Driven by hydrophobic and electrostatic forces, copper ions (II) could interact with bovine hemoglobin to form bovine hemoglobin-copper ions (II) complex with one binding site. The binding constant (K) was 1.57?×?10⁴, 1.89?×?10⁴ and 2.11?×?10⁴?L/mol at 298, 304, and 310?K, respectively. The binding distance (r) was 4.24?nm. Fluorescence and time-resolved fluorescence spectra showed that bovine hemoglobin quenched by copper ions (II) was a static quenching process. Results of synchronous fluorescence spectra revealed that the microenvironment and the conformation of bovine hemoglobin were changed during the binding reaction. Data of circular dichroism spectra suggested that with the increasing concentration of copper ions (II), the secondary structure of bovine hemoglobin underwent a decrease in α-helix and alteration in backbone microenvironment. Copper ions (II) was thus evidenced to have a certain toxic effect on physical bodies.     

Electric quadrupole interaction of 100Rh in antimony, hafnium and rhenium

The effects of the Mg(II)/Fe(III) ratio on the structure and Fe microenvironments in MgFe LDH substances were investigated. The LDHs were prepared by the co-precipitation method with Mg(II)/Fe(III) ratios from 2:1 to 6:1. The materials were characterized by ⁵⁷Fe Mössbauer spectroscopy and powder X-ray diffractometry. The ⁵⁷Fe Mössbauer spectra exhibited asymmetric doublet corresponding to high-spin Fe(III) microenvironments in all LDH structure. It was found that the quadrupole splitting decreased with increasing Mg(II)/Fe(III)ratio reflecting change in the electric field gradient due to the incorporation of different amounts of iron into the Mg-containing layers.     

Chemical transport reactions in the In-Sn-S ternary system: Existence of tin (II) and tin (IV) atoms by Mössbauer effect of119Sn in the isolated compounds

Iodine vapour transport, carried out in the In-Sn-S ternary system leads to single crystals with quite different morphologies: needles, sticks, sheets and polyhedra. The two oxidation states of tin atoms are shown for all these phases by¹¹⁹Sn Mössbauer effect. A varying relative proportion of tin(IV) — tin(II) is observed according to the different crystal forms.     

Perfect spin-filtering in p-aminophenol functionalized zigzag graphene nanoribbons: The role of sp3 hybridized nitrogen

Covalent functionalization of graphene is recently developed from the formation of sp³ hybridized carbon atom (sp³-C) to the sp³ hybridized nitrogen (sp³-N) at the anchoring site. Here, we investigated the electronic structures and transport properties of the zigzag graphene nanoribbons functionalized by covalently bonding of p-aminophenol (p-AP) molecule. First principles results demonstrate that the formed sp³-N plays a vital role in determining the electronic structure and transport properties of the system, resulting in a halfmetallic characteristic with a perfect spin-filtering behavior (100%). Interestingly, the performance of the spin-filtering is find to be insensitive to the sub-structures of the molecule. Our findings reveal the importance of sp³-N and suggest a new mechanism for realizing high-performance spin-filtering devices with functionalized graphene.     

Possible modification of level 1 trigger of the CDF muon system at increased Tevatron luminosity

The increase in the Tevatron (FNAL) luminosity up to ≥ 2.0 × 10³² cm^?2 s^?1 and the level 1 (L1) trigger rate limitation resulted in tougher event selection conditions at CDF II; this led, in particular, to elimination from L1 muon trigger data from muon detectors in the pseudorapidity interval 1 < |η| < 1.25. A new muon trigger is proposed and investigated; this trigger includes signals from an additional layer of scintillation counters in the above η interval. The modified L1 muon trigger provides an acceptable for CDF II rate of lower than 1 kHz.     

Positronium interactions with Cu(II) Ions in water

Summary Positronium reactions with Cu(II) ions in aqueous solution were investigated by measuring the concentration dependence of lifetime spectra and of 1D-ACAR curves for the following Cu (II) complexes: [Cu(H₂O)₆[²⁺, [Cu(NH₃)₄ (H₂O)₂]²⁺ and [Cu(EDTA)(H₂O)]²⁻. The combined analysis of lifetime and ACAR data shows that Cu(II) ions:a) reduce the formation of positronium (inhibition effect),b) promote both ortho ⇌ para conversion and redox reactions. It was also found that inhibition and reaction rate constants are affected by the ligand type.     

Mode I and Mode II interlaminar fracture toughness of CFRP/magnesium alloys hybrid laminates

The fiber metal laminates (FML), consisting of carbon fiber reinforced polymer prepregs and magnesium alloys sheets, were introduced, and the Mode I (peel) and Mode II (shear) interlaminar fracture toughness of the FMLs were investigated. The results show that the Mode I interlaminar toughness (0.23 kJ/m²) of the FMLs is much lower than the Mode II interlaminar toughness (5.81 kJ/m²), due to the fact that the effects of mechanical interlock to hinder crack propagates is smaller under Mode I loading conditions than under Mode II. The FMLs mainly show adhesive failure and interfacial failure under Mode I loading conditions, while for Mode II loading, it exhibits a degree of epoxy cohesive failure except the adhesive failure and interfacial failure.     

Li<Superscript>+</Superscript> ion conductivity and transport properties of LiYP<Subscript>2</Subscript>O<Subscript>7</Subscript> compound

A lithium yttrium diphosphate LiYP₂O₇ was prepared by a solid-state reaction method. Rietveld refinement of the X-ray diffraction pattern suggests the formation of the single phase desired compound with monoclinic structure at room temperature. The infrared and Raman spectrum of this compound was interpreted on the basis of P₂O₇ ^4? vibrations. The AC conductivity was measured in the frequency range from 100 to 10⁶ Hz and temperatures between 473 and 673 K using impedance spectroscopy technique. The obtained results were analyzed by fitting the experimental data to the equivalent circuit model. The Cole–Cole diagram determined complex impedance for different temperatures. The angular frequency dependence of the AC conductivity is found to obey Jonscher’s relation. The temperature dependence of σ _AC could be described in terms of Arrhenius relation with two activation energies, 0.87 eV in region I and 1.36 eV in region II. The study of temperature variation of the exponent(s) reveals two conduction models: the AC conduction dependence upon temperature is governed by the correlated barrier hopping (CBH) model in region I (T < 540 K) and non-overlapping small polaron tunneling (NSPT) model in region II (T > 540 K). The near value of activation energies obtained from the equivalent circuit and DC conductivity confirms that the transport is through ion hopping mechanism dominated by the motion of the Li⁺ ion in the structure of the investigated material.     

Intermediate structure in the 239Pu(d,pf) reaction

Sub-barrier resonances in the ²³⁹Pu(d, pf) reaction have been investigated with a resolution of 3 keV. Many class II resonance groups with an average spacing of 11 keV have been observed in the region of the 5.0 MeV transmission resonance. The coincident fission fragment angular correlations indicate a spin 2⁺ for all lines resolved. The data are analyzed on the basis of a simple model of intermediate structure which also explains the observed broadening of the class II groups.     

Synthetic hydroxyapatites doped with Zn(II) studied by X-ray diffraction,infrared, Raman and thermal analysis

Calcium hydroxyapatite (CaHap) formation when different amounts of Zn(II) are present in the mother solution has been investigated by atomic absorption, infrared and Raman spectroscopies, X-ray diffraction and thermal analysis (DTA and TG). The studied samples have been synthesized at T=95 °C and pH 9 in air. The analysis of the results have shown that the pure CaHap sample crystallizes in the monoclinic form P2₁/b. Concentrations up to 20% of Zn(II) in the mother solution, equivalent to smaller concentrations in solid (up to 9.1% in wt), favor the formation of the hexagonal apatite, P6₃/m, while Zn(II) concentrations higher than 20% in solution help an amorphous phase development where vibrational spectra indicated coexistence of two phases: an apatite and ZnNH₄PO₄·H₂O. Infrared data of thermal treated samples endorse that HPO₄²⁻ ion had not been incorporated in Zn(II) doped samples during the synthesis process. Present results also allow to conclude that Zn(II) cation exhibits a preference to occupy the Ca2 site of the apatite structure and induces water adsorption and a small quantity of CO₃²⁻ cation incorporation, leading to formation of a less crystalline Ca deficient apatite.     

Raman Spectra and Solvent-Solute Interaction of Mercury(II)-Thiocyanate Complexes in Some Aprotic Donor Solvents

Raman spectra of the species Hg(SCN)₂, [Hg(SCN)₃], and [Hg(SCN)₄]^2- in solution of ten aprotic donor solvents have been investigated in the region of the Hg-S vibration. Observed frequency values of measured band of Hg(SCN)₂ and [Hg(SCN)₃] in different solutions correlate well with donor strength of the solvents. There is a linearity between Hg-S frequency decreasing and increasing of the interaction of the solvent molecules with the mercury (II) ion in the thiocyanate complexes. No significant frequency changes have be found for [Hg(SCN)₄]^2-. Evidence based on the frequency shifts and depolarization ratios in various solvents supports the view that the Hg(SCN)₂ in solution undergos departure from linearity as a result of increasing solvent coordination to the mercury (II) ion. Almost constant frequencies of Hg-S vibration of [Hg(SCN)₄]^2- in all investigated solvents suggest a regular tetrahedral structure of the ion in solution having much larger radius than corresponding HgX₄ (X=Cl,Br,I) ions.     

Application of 57Fe-enriched synthetic ferrihydrite to speciate the product of bacterial reduction

We have sampled a clay lens with evidence of sulfide reduction from a texturally stratified sandy aquifer at Rømø, Denmark. A minor amount of synthetic, pure ⁵⁷Fe ferrihydrite was added to this sample and allowed to react for up to three months. The initial sample, the ⁵⁷Fe ferrihydrite, and samples taken from the reaction mixture were investigated by Mössbauer spectroscopy at temperatures between 15 and 298 K as sampled and following exposure to oxygen. The initial sample only contained Fe(II) (33% of the iron) and Fe(III) in silicates. The Fe(III) in the ferrihydrite is reduced to Fe(II) as evidenced by an increase of this component by bacterial activity. The Fe(II) component remains paramagnetic at temperatures down to 15 K. Similarly to naturally reduced sediments the new-formed Fe(II) is extremely reactive towards molecular oxygen. Following oxidation the reformed Fe(III) is found as ferrihydrite. The bonding of the Fe(II) is by electrostatical bonding (adsorbed) to the layer silicates as evidenced by a temperature scanning of the sample between 80 and 270 K.     

Characterization of the [Xtilde] 1Σ+ à 3Π and à 1Π electronic states of BBO

The three lowest-lying electronic states, [Xtilde] ¹Σ⁺, à ³II and à ¹II, of the linear BBO molecule have been systematically investigated using ab initio electronic structure theory. The equilibrium structures and physical properties including dipole moments, vibrational frequencies and associated infrared intensities, Renner parameters and energetics for the three states of BBO have been determined employing SCF, CISD, CCSD and CCSD(T) levels of theory and a wide range of basis sets. The ground state of BBO presents a degenerate real bending frequency, while the à ³II and à ¹II states show two distinct real bending frequencies due to the Renner-Teller interaction. The bending motion of the à ¹II state was analysed using the equation-of-motion (EOM)-CCSD and EOM-CC3 techniques in order to avoid possible variational collapse to a lower-lying state. The [Xtilde] ¹Σ⁺-à ³II separation was predicted to be T ₀ = 16.6 kcal mol^?1 (5800 cm^?1, 0.719 eV) at the cc-pVQZ CCSD(T) level of theory. With the cc-pVQZ EOM-CC3 method the [Xtilde] ¹Σ⁺-à ¹II splitting was predicted to be T ₀ = 48.0 kcal mol^?1 (16 800 cm^?1, 2.08 eV), which is in good agreement with the experimental value of T ⁰ = 46.6 kcal mol^?1 (16 300 cm^?1, 2.02 eV). The Renner parameters and averaged harmonic frequencies of the bending mode were determined to be ? = 0.184 and ω₂ = 363 cm^?1 for the à ³II state, and ? = 0.246 and ω₂ = 383cm^?1 for the à ¹II state. The theoretical [Xtilde] ¹Σ⁺ state harmonic B-B stretching frequency ω₃ = 636 cm^?1 is somewhat higher than the experimental estimate of 582 cm^?1 and the predicted à ¹II state harmonic B-B stretching frequency ω₃ = 861 cm^?1 is significantly higher than the experimental estimate of 440 cm^?1     

A pulsed EPR study of the catalytic oxidation of CO over Cu/SnO2

The role of the Cu(II) in the catalytic oxidation of CO over Cu/SnO₂ with low Cu(II) content was studied by continuous wave EPR, electron spin echo envelope modulation (ESEEM) and hyperfine sublevel correlation (HYSCORE) spectroscopes. Three methods were employed for introducing the copper: (i) by coprecipitation, (ii) impregnation onto SnO₂ gel and (iii) impregnation onto calcined SnO₂. Two types of Cu(II) species were identified in these calcined Cu/SnO₂ materials. Those belonging to the first type, termed B and C, exhibit highly resolved EPR spectra with well defined EPR parameters and are located within the bulk of the oxide. The other group comprises a distribution of surface Cu(II) species with unresolved EPR features and are referred to as S. While the latter were readily reduced by CO the former required long exposures at high temperatures (> 673 K). The specific interactions of the different Cu(II) species with CO were investigated through the determination of the¹³C hyperfine coupling of enriched¹³CO. The ESEEM spectra of calcined samples, generated either by coprecipitation or impregnation, show after the adsorption of CO signals at the Larmor frequencies of^{117, 119}Sn and¹³C and at twice these Larmor frequencies. Although these signals indicate that^{117, 119}Sn and¹³C are in the close vicinity of Cu(II), they cannot provide the hyperfine couplings of these nuclei. This problem was overcome by the application of the HYSCORE experiment. The 2D HYSCORE spectra show well resolved cross peaks which provide the hyperfine interaction of these nuclei. Simulations of the HYSCORE spectra yield for^{117, 119}Sn an isotropic hyperfine constant,a _iso, of ±4.0 MHz and an anisotropic component,T _?, of ±2.0 MHz. Pulsed ENDOR spectra also showed^{117, 119}Sn signals which agree with the above values. The¹³C cross peaks yielda _iso=±1.0 MHz andT _?=±2.0 MHz. Similar C cross peaks were observed in spectra of calcined Cu/SnO₂ after the adsorption of CO₂. Based on the same hyperfine couplings in the samples exposed to¹³CO and¹³CO₂ the signals were assigned to surface carbonate species generated by part of the Cu(II) S type species rather then by species B and the role of the Cu(II) in the oxidation process is discussed.     

Studies of molecular oxygen adsorbed on Cu surfaces

Molecular oxygen adsorbed on (110) and polycrystalline Cu surfaces has been investigated by UPS, XPS, AES, HREELS and LEED. Molecularly adsorbed O₂ on the (110) surface shows the characteristic three-peak He II spectrum due to π_g, π_u and σ_g orbitals, accompanied by an O-O stretching frequency at 660 cm⁻¹. On the polycrystalline Cu surface, adsorbed O₂ shows the three peak He II spectra with a considerably smaller separation between the π_u and σ_g band and two O-O stretching bands at 610 and 880 cm⁻¹. O₂ adsorbed on the Cu(110) surface gives rise to a (1 × 1) LEED pattern and characteristic K π¹π¹ transition in the Auger spectrum.     

Study of the transport mechanism in molecular self-assembling devices

This paper focuses on the intrinsic charge transport in self-assembled monolayers (SAMs) and on the nature of transport in organic systems, in which surface and bulk properties are undistinguishable due to scale of consistent materials. Developed SAM-OFETs and photovoltaic (SAM-PVC) devices are characterized independently to study a role of charge delocalization both in electrical and optical manifold. The dynamics of charge transport are determined and used to clarify a transport mechanism. Taken together, these SAM devices provide a unique tool to study the fundamentals of polaronic transport on organic surfaces and to discuss the SAM-OFET and SAM PVC performance. Vapor phase molecular self-assembly of 1, 4, 5, 8-naphthalene-tetracarboxylic diphenylimide (NTCDI) having a rich π-stacking charge delivery system is used to enhance the performance of SAM-OFET and SAM PVC devices. Charge mobility in SAM-OFET could achieve values of more than 30 cm² V⁻¹ s⁻¹. The dynamics of charge transport in NTCDI-derived SAM-OFETs were probed using time-resolved measurements in an NTCDI-derived photovoltaic cell device. Time-resolved photovoltaic studies allow us to separate the charge annihilation kinetics in the conductive NTCDI channel from the overall charge kinetic in a SAM-OFET device. It has been demonstrated that tuning of the type of conductivity in NTCDI SAM-OFET devices is possible by changing Si substrate doping. In addition, the possibility of measuring transport in highly ordered SAM structures shines light on the polaron charge transfer in organic materials. Our study proposes that a cation-radical exchange (redox) mechanism is the major transport mechanism in SAM nanodevices. The role and contribution of the transport through delocalized states of redox active surface molecular aggregates of NTCDI are exposed and investigated in this report.     

Bifunctional Calix[4]arene Sensor for Pb(II) and Cr2O7 2− Ions

A readily available chromionophore 5,11,17,23-tetra-tert-butyl-25,27-bis(hydrazidecarbonylmethoxy)-26,28-dihydroxycalix[4]arene (HCC4) was employed as a chromogenic sensing probe selective for Pb(II) and Cr₂O₇ ^2? ions among a series of various ions such as Li(I), Na(I), K(I), Rb(I), Ba(II), Sr(II), Al(III), Cd(II), Co(II), Cu(II), Hg(II), Ni(II), Pb(II) and Zn(II) as well as Cr₂O₇ ^2?, CH₃CO₂ ^?, Br^?, Cl^?, F^?, I^?, ClO₄ ^? and NO₃ ^? that have been examined by UV-visible and fluorescence spectroscopic techniques. The HCC4 in DCM-MeCN system forms 2:1 (ligand-metal) complex with Pb(II). It also shows 2:1 stoichiometry with Cr₂O₇ ^2?. The complexation phenomenon has been confirmed by FTIR spectroscopy that favors the selective nature of HCC4 with Pb(II) and Cr₂O₇ ^2?. Thermal gravimetric analysis (TGA) also supports its utility in drastic conditions.     

Energetic proton emission in heavy ion collisions at intermediate energy: Pre-equilibrium and cooperative effects

Energetic proton emission has been investigated as a function of the centrality in the reaction ⁵⁸Ni + ⁵⁸Ni at 30 AMeV. Protons with energy extending up to a relevant fraction of the total available energy in the reaction were measured and studied. The dependence on the reaction centrality has been extensively investigated and data have been compared with the results of microscopic transport calculations. The more striking observation concerns the extremely energetic proton (E^NN _P ≥ 130 MeV) multiplicity which is found to increase almost quadratically with the number of participant nucleons thus indicating the onset of a mechanism beyond one and two-body dynamics.