Dq Values Research Articles

Breakdown of the Landauer bound for information erasure in the quantum regime.

A known aspect of the Clausius inequality is that an equilibrium system subjected to a squeezing dS < 0 of its entropy must release at least an amount the absolute value of dQ = T times the absolute value of dS of heat. This serves as a basis for the Landauer principle, which puts a lower bound T ln 2 for the heat generated by erasure of one bit of information. Here we show that in the world of quantum entanglement this law is broken. A quantum Brownian particle interacting with its thermal bath can either generate less heat or even absorb heat during an analogous squeezing process, due to entanglement with the bath. The effect exists even for weak but fixed coupling with the bath, provided that temperature is low enough. This invalidates the Landauer bound in the quantum regime, and suggests that quantum carriers of information can be more efficient than assumed so far.

Studies On Some Acid Divalent-Metal Nitrilotriacetate Complexes

IR and 1H-NMR studies on nitrilotriacetic acid (H3NTA) suggest that the acid exists in the zwitterion form, which allows the existence of intermolecular hydrogen bonding. A tetrahedral structure is established for eleven (1:1) anhydrous acid-metal (II) nitrilotriacetates complexes. The ten Dq values for the colored complexes were determined spectrophotometrically. The pKa values for the eleven acid metal complexes [M(HNTA)].(OH2)3] were determined and compared with the corresponding pKa values of the [M(OH2)n]+2 ions and also with the log β1 values of the corresponding [M(NTA)]- complexes. X-ray diffraction studies on the ligand and on eight of these complexes are described.

Local relaxation aroundFe3+in fluorides: Influence on electronic properties

with the v(A1g) frequency for both kind of impurities. From the present results Re changes caused by a hydrostatic pressure down to 0.05 pm can be detected through As variations measured by ENDOR. Moreover it is pointed out that good information about the actual impurity-ligand distance for transition-metal impurities in insulators can be obtained from DF calculations on clusters. Finally, the 10 Dq value and its R dependence are shown to be strongly related to the small 3 d-2s(F) hybridization in the antibonding e g level which also determines As .

Czochralski growth and optical spectral properties of GInGG: Cr 3+ single crystal

GInGG: Cr 3+ crystal was grown by the Czochralski technique for the first time. The Optical absorption and fluorescence spectra were measured at room temperature and 77 K. Two wide absorption bands occur at 457 and 643nm. A highly efficient emission from 670–1050nm with a peak at 771nm was observed at 289K. The energy levels were fitted by means of Tanabe-Sugano matrices and the values of Dq, B and C were calculated to be 1555, 637 and 3226 cm −1, respectively.

Influence of isomorphous cation and anion substitution on optical spectra of cobalt alkylaminehalide crystals

Based on data of spectral investigations of crystals with the group A2CoCl4 (A=NH2(C2H5) 2 + , N(C2H5) 4 + , N(CH3) 4 + ) and [N(C2H5)4]2CoCl2Br2, the identification of absorption bands corresponding to internal electron transitions in a Co2+ ion has been carried out. The values of the crystalline field force Dq for the above-indicated materials at room temperature have been determined. The regularities of the change in the given parameter with change in the temperature and isomorphous cation-anion substitution have been established. It is shown that substitution of chlorine ions by bromine ions in the [N(C2H5)4]2CoCl2Br2 solid solution leads to the formation of distorted tetrahedral complexes CoCl2Br2.

Quantitative analyses of the change in microbial diversity in a bioreactor for wastewater treatment based on respiratory quinones

The change in microbial diversity in a submerged aerobic biofilter, into which a persistent chemical of dimethylformamide was fed, were analyzed based on the quinone profiles using a new diversity index of the respiratory quinones (DQ) and an index of equitability of the distribution of quinone species (EQ) originally proposed in this study: DQ=(∑ f 1/2 k ) 2, EQ=DQ/ n. Where, f k is the mole fraction of quinone species k and n is the number of quinone species, respectively. The DQ value increases with an increase in the number and the equitability of the distribution of quinone species. In the case where the mole fractions of all quinone species are equal, the value of DQ becomes equal to the number of quinone species and the EQ value becomes 1. A simulation analyses shows that DQ has a higher sensitivity to the change in number of quinone species than Shannon's index, i.e. one of the most widely used diversity indices. The relative sensitivity of DQ to the change in mole fraction of quinone species is higher than that of Shannon's diversity index for natural ecosystems in which many kinds of quinone species exist and occupy smaller fractions. The quinone profiles of the biofilm significantly changed and the values of DQ and EQ increased during the acclimation of the biofilm to dimethylformamide in the biofilter. The plot of the mole fraction of dominant quinone species to the DQ values showed higher sensitivity to the change in the microbial community. These results indicated that DQ and EQ are useful indices for the evaluation of the changes in the microbial community in response to environmental conditions.

Hydrothermal synthesis, structural, spectroscopic and magnetic studies of a lamellar phosphate: Ba(MnPO4)2ṡH2O

Ba(MnPO 4 ) 2 ·H 2 O has been prepared by hydrothermal synthesis and characterized by spectroscopic and magnetic techniques. Its crystal structure has been solved from X-ray powder diffraction data by using direct methods and refined with the Rietveld method. The compound crystallizes in the monoclinic system in the C2 space group with unit cell parameters, a = 9.457(1), b = 4.984(1), c = 8.346(1) A and β = 92.07(1)°. The structure consists of a two-dimensional network of MnO 6 octahedra, linked by phosphate anions and water molecules, which form chains along the |010| direction. The luminescence properties of Mn(II) in the compound are studied and the values of Dq and Racah parameters B and C have been calculated. The EPR spectra recorded on a polycrystalline sample at different temperatures show isotropic signals with g-values of 2.0. The intensity of the EPR signals increases with decreasing temperature down to 45 K and at lower temperatures rapidly decreases. Magnetic measurements show the presence of antiferromagnetic interactions. An analysis of the magnetic behaviour was carried out considering a theoretical model for antiferromagnetic chains with spin S = 5/2. Similar values for the J-exchange parameter inside the chains (J/k = –2.0 K) and for the J′-exchange parameter between neighbouring chains (zJ′/k = –2.0 K) are observed. These results suggest that the compound can be considered as a non-regular two-dimensional magnetic system.

Synthetic models for the glucose tolerance factor: the spectroscopic characterization and toxicity studies of monomeric and dimeric Cr(III) species

A number of chromium(III) complexes with glycine, cysteine, glutamic and nicotinic acids-models for biologically active Cr(III) species have been prepared and characterized with physicochemical methods (UV\\Vis, IR spectra, magnetic moments). Four of them have been also tested for their toxicity. On the basis of CF calculation it was found that only the nicotinates were octahedral Cr(III) species. Other complexes exhibited a tetragonal deformations. Based upon 10 Dq values, the sequence of the ligand field strength was found to be: glycine>cysteine≈glutamic acid>nicotinic acid. The likely structures were proposed for the isolated compounds. The preliminary toxicity studies showed that all tested complexes appeared to be non-toxic and can be potentially applied as chromium nutrition products.

Photoacoustic powder spectra of Ni(II) and Co(II) complexes with aromatic amine N-oxide ligands

A photoacoustic double-beam powder spectrometer that works with lock-in technique implemented as software in a personal computer is described. The influence of mechanical vibrations have been removed by applying the added signal from two microphones placed face to face. The spectra of six Ni(II) and three Co(II) complexes with aromatic N-oxide ligands have been presented and the value of Dq has been compared with values determined with known spectra.

High value of the radiobiological parameter Dq correlates to expression of the transforming growth factor β type II receptor in a panel of small cell lung cancer cell lines

Our panel of SCLC cell lines have previously been examined for their radiobiological characteristics and sensitivity to treatment with TGF β 1. In this study we examined the possible correlations between radiobiological parameters and the expression of the TGF β type II receptor (TGF β-rII). We have, in other studies, shown that the presence of TGF β-rII was mandatory for transmitting the growth inhibitory effect of TGF β. The results showed a statistically significant difference in D q, i.e. the shoulder width of the survival curve, between cell lines expressing TGF β-rII and cell lines which did not express the receptor ( P=0.01). Cell lines expressing TGF β-rII had a high D q-value. TGF β-rII expression did not correlate with any other radiobiological parameters. We suggest that an intact growth inhibitory pathway mediated by the TGF β-rII may have a significant role for the repair of radiation induced DNA damage in SCLC.

Pilocarpine, a salivary gland radioprotectant, does not inhibit cytotoxic effect of γ-radiation on squamous cell carcinoma in vitro

Pilocarpine, a salivary stimulant, has been shown to protect salivary glands from gamma-radiation-induced damage during the radiotherapy of head and neck tumors. This study was performed to determine whether pilocarpine affects the survival of squamous carcinoma cells, line SCC-25, following gamma-radiation treatment. The survival of squamous carcinoma tumor cells, line SCC-25, following the exposure of cells to pilocarpine at concentration of 0-100 ng/ml given for 0-1 h prior to radiation at dose of 0-20 Gy was determined by an in vitro colony-formation assay. The survival fractions of SCC-25 cells were identical for the control and pilocarpine-treated samples at all tested conditions. Calculated Do and Dq values did not depend on the presence of pilocarpine and were not affected by the time of incubation prior to irradiation. Pilocarpine, at clinically relevant concentrations, given to the SCC-25 cells 1 h prior to or at the time of irradiation did not affect survival of SCC-25 cells in vitro. Pilocarpine does not sensitize or protect these tumor cells from the effects of y-radiation, suggesting that this agent should not compromise the tumoricidal effects of radiotherapy.

Multifractal Measures of Time Series of Earthquakes.

The generalized fractal dimensions are measured for the time series based on two complete earthquake catalogues: one with M≥6 earthquakes occurring in the north-south seismic belt of mainland China during the 1900-1990 period published by Ma et al. (1992) and the other with M≥5.5 earthquakes occurring in southern California, USA during the 1915-1994 period compiled by Press and Allen (1995). The log-log plot of Cq versus t, where Cq(t) is the generalized correlation integral and t is the interoccurrence time in years between two events, at positive q shows a linear istribution when t<tc. Dq is the slope of this linear portion. The value of tc decreases from 50.1 to 39.8 years for Chinese earthquakes and from 50.1 to 31.6 years for southern California events as q is increased from 0 to 15. For M≥6 Chinese earthquakes, the well-distributed, monotonically decreasing function of Dq, with increasing q would imply that such earthquakes have formed a multifractal time series. In contrast, the M≥5.5 southern California earthquakes might have not yet formed a complete multifractal time series or the number of these events is too small to accurately estimate the multifractal dimensions, especially for large qs. Different degrees of complexity of fault distributions in the two seismic regions might also be a factor in causing the difference in the Dq-q relations. In addition, the results also suggest that a Dq-q relation is better than the first three commonly-used values of Dq to completely represent a multifractal time series.

Extracellular Matrix (ECM) and Cytoskeletal Modulation of Cellular Radiosensitivity

Modulation of radiosensitivity by components of the extracellular matrix (ECM) and cytoskeletal elements has not been adequately studied. Although differences in the radiosensitivities of cells grown as monolayers, as spheroids, or grown in vitro in animal models are known, explanations have in the past neglected possible influences by the ECM and cytoskeleton. Using collagen gel cultures, it is shown that the fibrillar component of the ECM (which is responsible for cell anchorage) induces shifts in radiosensitivity. The effect is critically dependent on the affinity of the cell type towards collagen. The shifts in radiosensitivity induced by ECM alteration are manifested as changed Dq values. By applying four specific cytoskeletal poisons which either stabilize or destabilize specific cytoskeletal elements, the involvement of microfilaments and microtubuli was qualitatively appraised. Cytochalasin B, which destabilizes microfilaments (by preventing polymerization), caused a significant rise in radioresistance. This rise was due to increased Do. Although the cellular morphological change accompanying cytochalasin B treatment was essentially similar to that obtained with trypsin, the respective shifts in radioresponses were qualitatively different and opposite, suggesting differences in mechanism of action.

Hard–soft interactions in early transition-metal thioether macrocyclic chemistry: spectroscopic and extended X-ray absorption fine structure studies on chromium(III) thioether complexes

S. J. A. Pope, N. R. Champness and G. Reid, J. Chem. Soc., Dalton Trans., 1997, 1639 DOI: 10.1039/A608332C

Polarized electronic absorption spectra of Co2+ ions in the kieserite-type compounds CoSO4 � H2O and CoSeO4 � H2O

Polarized electronic absorption spectra of the kieserite-type compounds CoSO4 · H2O and CoSeO4 · H2O have been obtained at room temperature (spectral range 35 000-5000 cm-1) and at liquid nitrogen temperature (visible spectral region), using microscope-spectrometric techniques. The spectra are interpreted and evaluated in terms of a tetragonal crystal field formalism for the d7 configuration, in regard to the pseudotetragonal elongation of the CoO4(H2O)2 octahedra, known from previous X-ray structure investigations, employing the tetragonal parameters Dq, Dt, and Ds, and the Racah parameters B and C. The observed and calculated energy levels are in good agreement for the following parameter sets: CoSO4 · H2O: Dq=826, Dt=40, Ds=350, B=856, C=3580 cm-1; CoSeO4· H2O: Dq=817, Dt=44, Ds=406, B=841, C=3490 cm-1; corresponding ‘cubic’ crystal field strengths Dqcub are 803 and 792 cm-1, respectively. The values of Dq(cub), Racah B and C are in the common range for Co2+ ions in (pseudo) octahedral fields of oxygen ligands, and their differences in CoSO4· H2O compared to CoSeO4 · H2O are consistent with somewhat different mean Co-O bond lengths and with a slightly higher covalent contribution to Co-O bonding in the selenate compound. The values found for the parameter Dt, which is directly correlated to the extent of tetragonal distortion, are much lower than expected from purely geometrical considerations, thus confirming a significantly higher position of H2O ligands in the spectrochemical series compared to oxygen ligands belonging to SO4 or SeO4 groups.

An optical study of silicate glass containing and ions

The optical properties of chromium-doped sodium silicate glass synthesized under oxidizing conditions have been investigated. The method of preparation provides a large concentration of ions, but absorption and emission spectra showed that a small amount of (and ) ions are always present. The Dq-, B- and C-parameters of the crystal-field theory for the ion were obtained, confirming the glassy nature of the sample. luminescence was observed in the near-infrared region, even at room temperature, confirming the low value of the crystal-field Dq. Moreover, the high ultraviolet transparency of this matrix allows observation of a well resolved absorption spectrum of the ion.

Electron-spin resonance studies of the titanium cation (Ti+,3d3,4F) in rare gas matrices at 4 K: A crystal field interpretation

Electron-spin resonance studies of laser-ablated titanium metal isolated in neon and argon display an intense feature which exhibits a symmetric, narrow line and a large matrix-dependent g shift. On the basis of a number of experiments, this is assigned to a matrix isolated 3d3,4F Ti+ ion in an octahedral matrix environment. Although the ground state of the gas-phase Ti+ ion is 3d24s1,4F, the assignment to the 3d3,4F state is supported by the small hyperfine structure which is observed. The neon magnetic parameters are: g=1.934(1) and A(47Ti)=64(1) MHz; for argon, g=1.972(1) and A=56(1) MHz. This unusual stabilization of an excited atomic state by a rare gas matrix is consistent with ab initio studies, and has been previously found for atomic nickel. A crystal-field study of the expected behavior of a d3,4F ion isolated in a tetrahedral, octahedral, or cuboctahedral environment supports the assignment to an octahedral Ti+(Rg)6 species, and using the atomic spin–orbit parameter, ζ permits accurate values of Dq to be derived from the measured g values. Finally, it is also noted that for small values of Dq/(Dq+ζ), or for a d3,4F ion in a tetrahedral environment, an as yet unobserved, unequal Zeeman splitting of the fourfold degeneracy occurs, causing a departure of the Zeeman energies from the standard formula of EZeeman=βeH0gM, with M=±3/2, ±1/2. For these situations it becomes necessary to define two values of g, corresponding to the more strongly (g3/2) and less strongly (g1/2) affected Zeeman levels, respectively.

Manganese L-Edge X-ray Absorption Spectroscopy of Manganese Catalase from Lactobacillus plantarum and Mixed Valence Manganese Complexes

The first Mn L-edge absorption spectra of a Mn metalloprotein are presented in this paper. Both reduced and superoxidized Mn catalase have been examined by fluorescence-detected soft X-ray absorption spectroscopy, and their Mn L-edge spectra are dramatically different. The spectrum of reduced Mn(II)Mn(II) catalase has been interpreted by ligand field atomic multiplet calculations and by comparison to model compound spectra. The analysis finds a 10 Dq value of ∼1.1 eV, consistent with coordination by predominately nitrogen and oxygen donor ligands. For interpretation of mixed valence Mn spectra, an empirical simulation procedure based on the addition of homovalent model compound spectra has been developed and was tested on a variety of Mn complexes and superoxidized Mn catalase. This routine was also used to determine the oxidation state composition of the Mn in [Ba8Na2ClMn16(OH)8(CO3)4L8]·53H2O (L = 1,3-diamino-2-hydroxypropane-N,N,N‘,N‘-tetraacetic acid).

Local relaxations and optical properties of Cr3+ in MgO

Abstract Local distortions and optical properties induced by the substitutional Cr3+ impurity in the MgO host lattice are computed using the embedded cluster approach implemented in the ICECAP (ionic crystal with electronic cluster, automatic program) code. Our calculations predict inward relations of the six O2− nearest neighbors surrounding the Cr3+ ion for both cubic and noncubic (tetragonal and orthorhombic) configurations in MgO. For the cubic configuration, selected low-lying excited states, including the 10 Dq generator 4T2, are calculated at several Cr-O separations. After taking into account lattice relaxations and correlation corrections, the computed 10 Dq value lies 0.19 eV lower than the experimental one.

Theoretical calculations of pressure-induced shifts of the entire energy spectrum of ruby

The d3 ions in trigonal crystal fields are considered. On the basis of the expansion of the electron wavefunctions under pressure, the expressions for the parameters Dq, B, C, K, K' and zeta as functions of the linear compression ratio chi are derived, and the complete d3 energy matrix in trigonal field is constructed. With the P-chi dependence, by diagonalization of this matrix to fit only the experimental data of the red shifts of ruby R1 line under quasihydrostatic pressure, the values of three parameters for the pressure shift (S0, D1 and t) are determined. Then, the values of Dq, B, C, K, K' and zeta at various pressures are evaluated, and the pressure shifts of the entire energy spectrum of ruby are theoretically calculated uniformly by diagonalization of the complete d3 matrix. The contributions of changes of Dq, B, C, K, K' and zeta to the R1 and R2 red shifts and the pressure-induced change in the R1-R2 splitting are obtained. The calculated results of the pressure shifts are in good agreement with all the experimental data of the R-, R'- and B-line groups and U and Y bands. A discussion is given and conclusions drawn.