bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dermcidin expression confers a survival advantage in prostate cancer cells subjected to oxidative stress or hypoxia
Authors: Stewart Grant D. , Lowrie Alastair G. , Riddick Antony C. P. , Fearon Kenneth C. H. , Habib Fouad K. , Ross James A. 
Published: July 2007

AbstractBACKGROUNDDermcidin (DCD) is a candidate survival gene in breast cancer. DCD gene expression has been identified in prostate cancer cell lines and primary prostate cancer tissue. The DCD protein is composed of proteolysis‐inducing factor‐core peptide (PIF‐CP) and the skin antimicrobial DCD‐1. The aim of this work was to: (i) establish if the DCD gene confers resistance of prostate cancer cells to hypoxia and oxidative stress; (ii) identify the component of the gene transcript responsible for this effect.METHODSSite‐directed mutagenesis was used to create mutant DCD vectors. PC‐3M prostate cancer cells were stably transfected with pcDNA3.1+ vectors encoding the entire DCD cDNA, mutant DCD vectors, or a control empty vector. Oxidative stress was produced using menadione, glucose oxidase, or hydrogen peroxide. Cell hypoxia was induced by incubation at 0.2% oxygen.RESULTSComparison of cell growth showed a 54.5% relative‐proliferative advantage for the DCD‐transfected PC‐3M cells compared with sham‐transfected cells after 8 days of cell growth (P = 0.03). Overexpression of DCD provided upto 36% absolute survival advantage over sham‐transfected cells following induction of oxidative stress or hypoxia (P = 0.004). On exposure to hypoxia or oxidative stress PC‐3M cells overexpressing the entire DCD gene had upto 42% survival advantage over those transfectants lacking the PIF‐CP sequence (P = 0.004).CONCLUSIONSDCD and PIF‐CP are proliferation and survival factors in prostate cancer cells subjected to stressors found in the prostate cancer microenvironment. Thus, DCD and specifically PIF‐CP are potential targets for the treatment of prostate cancer. Prostate 67: 1308–1317, 2007. © 2007 Wiley‐Liss, Inc.
Androgen receptor‐mediated repression of novel target genes
Authors: Prescott Jennifer , Jariwala Unnati , Jia Li , Cogan Jon P. , Barski Artem , Pregizer Steve , Shen Howard C. , Arasheben Armin , Neilson Jessica J. , Frenkel Baruch , Coetzee Gerhard A. 
Published: July 2007

AbstractBACKGROUNDThe androgen receptor (AR) plays a pivotal role in prostate cancer (PCa) initiation and progression. To date, studies have focused disproportionately on androgen‐stimulated genes such as prostate‐specific antigen (PSA), while repressed genes have gained little attention, even though they too may be involved in regulating cell growth, differentiation, and apoptosis.METHODSChIP Display was used to identify putative AR target genes in the ablation‐resistant human PCa cell line, C4‐2B. Quantitative real‐time reverse transcription‐PCR analysis was used to measure gene expression in cells subjected to dihydrotestosterone (DHT) timecourse and dose–response, as well as AR knock‐down and bicalutamide‐treatments.RESULTSWe report on three genes, KIAA1217, CHRM1, and WBSCR28, which were newly identified in a screen for AR‐occupied regions in C4‐2B PCa cells, and which were repressed by treatment with DHT. AR knock‐down resulted in increased KIAA1217, CHRM1, and WBSCR28 mRNA, indicating that, like PSA stimulation, AR represses these three genes even in the absence of added ligand. DHT decreased KIAA1217 and CHRM1 pre‐mRNA levels, suggesting AR‐mediated transcriptional inhibition. Cycloheximide attenuated DHT‐mediated repression of CHRM1, suggesting the requirement of new protein synthesis. Furthermore, bicalutamide treatment did not mimic, but rather antagonized DHT‐mediated KIAA1217 repression. Unlike the handful of androgen‐repressed genes studied thus far, AR occupancy at KIAA1217, CHRM1, and WBSCR28 was mapped outside their respective 5′‐promoter regions.CONCLUSIONSMany more genes likely share AR‐mediated gene repression through distal regulatory elements. Further study of such targets and their transcriptional regulation may help explain the receptor's tumorigenicity in PCa. Prostate 67: 1371–1383, 2007. © 2007 Wiley‐Liss, Inc.
Anharmonic effects in germanium
Authors: Saravanan R. , Mohanlal S. K. , Nethaji M. 
Published: July 2007

AbstractA precise X‐ray investigation is carried out to probe the lowest‐order anharmonic contribution of the atomic potential of the germanium atom. A total number of 1052 reflections (h + k + l = 4n and 4n ± 1) are precisely measured at room temperature using a spherical single crystal of germanium and using a Nonius CAD‐4 X‐ray diffractometer with crystal monochromatized MoKα radiation. A least‐square refinement program is used to refine the harmonic and anharmonic thermal parameters of the crystal. The refinement gives βGe = (−0.749 ± 1.79) × 10−16 J nm−3 with BGe = (0.528 ± 0.004) × 10−2 nm−2. The reliability index (R) amounts to 1.71% for germanium.
Matrix elements of the electron‐phonon interaction in the fourier‐based representation of a crystal potential
Authors: Novysh B. V. , Gololobov E. M. , Dorozhkin N. N. 
Published: July 2007

AbstractA method for electron‐phonon matrix element calculations based on a Fourier representation of the crystal potential is presented. This method is free from a number of drawbacks inherent to the rigid muffin‐tin approximation. At the same time it is much easier realizable as compared with the first‐principle frozen‐phonon technique. The long‐range interactions, the collective character of ion displacements in phonon modes, and effects due to in‐sphere electron‐ion potential anisotropy can be easily taken into account. Non‐muffin‐tin corrections are shown to cause electron‐ion scattering selection rule variations. Interband transitions due to absorption or emission of optical phonons with q = 0 (e.g. Raman‐active Ag modes) require the inclusion of nonlinear ion displacement contributions to the matrix elements.
Properties of a high‐mobility two‐dimensional electron gas in modulation‐doped quantum well structures of GaInAs/AIInAs and GaInAs/(Ga1−xAlx)InAs heterostructures
Authors: Kraak W. , Oelze B. , Künzel M. , Bach H.‐G. , Bötiger J. , Nakov V. , Schulze D. , Gobsch G. 
Published: July 2007

AbstractThe electronic and magnetotransport properties of the two‐dimensional electron gas (2DEG) in MBE‐grown GaInAs/AlInAs and GaInAs/Ga1−xAlxInAs heterostructures are investigated in magnetic fields up to 12 T. The quantum oscillations of the magnetoresistivity (SdH effect) and the observation of pronounced quantum Hall effect demonstrate the existence of a high‐mobility 2DEG in the GalnAs potential well. The characteristic parameters of the electronic band structure of the 2DEG are determined and are compared with self‐consistent solutions of the coupled Poisson and Schrödinger equations. The influence of hydrostatic pressure on the magnetotransport properties is studied. A surprisingly weak change of the subband occupation with pressure is revealed.
XPS study of KTaO3, KTa0.69Nb0.31O3, and KNbO3 single crystals
Authors: Winiarski A. , Neumann T. , Mayer B. , Borstel G. , Neumann M. 
Published: July 2007

AbstractXPS measurements were performed on in situ split KTaO3, KNbO3, and cubic KTa0. 69Nb0. 31O3 single crystals. The spectra are compared with the results of electronic structure calculations for the pure bulk materials in the cubic phase, based on the self‐consistent scalar‐relativistic linearized muffin‐tin orbital (LMTO) method. Comparing the experimental and calculated spectra good agreement is found. Angle‐resolved XPS experiments show distinct surface contributions to the recorded spectra, especially to the potassium peaks and in the valence band region.
The role of covalency and bridging ligands in two‐ion cooperative optical transitions in lanthanide ion‐coupled systems
Authors: Mironov V. S. , Kaminskii A. A. 
Published: July 2007

AbstractThe influence of covalency and bridging ligands on cooperative optical effects in dimers with closely coupled lanthanide ions in insulating crystals and binuclear complexes is theoretically treated. It is shown that there is a specific interaction between Ln3+ ions (which may be called covalent coupling) in tight ion pairs originating from virtual electron hoppings between lanthanide ions via common bridging ligands. This interaction can be regarded as a generalization of the superexchange interaction mechanism. A general microscopic model and the corresponding formalism for the covalent coupling mechanism are developed. A general expression to estimate the intensity of electric dipole two‐ion cooperative optical transitions is derived. Both the nature of bridging ligands and the local geometry of the Ln3+ (A)–ligandLn3+ (B) dimer are found to affect strongly the intensities of cooperative transitions. Our model predicts rapid increase in the contribution of this mechanism to the intensities of two‐ion transitions when going from small “ionic” ligands (F− and O2−) to large “covalent” ligands (Br−, I−). Possible manifestations of the covalent coupling mechanism in fast energy transfer processes and unusually strong up‐conversion fluorescence observed in CsCdBr3 : Ln3+ systems and as well as in electronic spectra of the U2Cl10 binuclear compound are discussed.
Frequency dependent losses in REBa2Cu3O7 (RE = Dy, Ce)
Authors: Roy D. , Deb S. K. , Neogy C. , Nag A. 
Published: July 2007

AbstractFrequency dependent response of DyBa2Cu3O7 and CeBa2Cu3O7−x is measured by a simple contactless method over a wide frequency range (1 KHz to 13 MHz) at 300 and 77 K. The volume fraction of the superconducting phase can be easily estimated by the method. It is seen that χ′ (≈ −1/4π × Meissner fraction) for DyBa2Cu3O7 at 77 K is independent of frequency up to 10 MHz in the Meissner state. For CeBa2Cu3O7−x which is a non‐superconducting insulator, χ′ is positive and increases with frequency both at 300 and 77 K (χ′ (77 K) < χ′ (300 K)). The relaxation mechanism for the ac conduction in DyBa2Cu3O7 in the normal state is suggested to be primarily due to tunnelling and hopping of 2p hole polarons located at oxygen sites.
Theory of a Confinement Effect of Dipole Rotations Resulting in Saturation in Microwave Heating of Ceramics
Authors: Endicott M. R. , Kenkre V. M. , Kuś M. 
Published: July 2007

AbstractRecent observations on microwave heating in ceramic materials have included saturation effects wherein the dependence of the heating rate on microwave power becomes sublinear, with a resulting decrease in efficiency relative to standard Joule heating. A model based on absorption by bivacancy rotations is shown to account for the anomalous power dependence. Rotation, by its very nature, is shown to result in an effective confinement of the dipoles and to reproduce the sublinear effect both qualitatively and quantitatively. Explicit calculations are presented for a simple model, the results are examined in the light of observations on ferric oxide, and the rotational absorber model is compared with a translational counterpart treated earlier.
Transmission Resonance Pattern in Finitely Periodic Simple Impurity Doped Superlattice Structures
Authors: Kalotas T. M. , Lee A. R. , Common A. K. 
Published: July 2007

AbstractThe resonance spectrum of a finitely periodic Superlattice system is analysed for the special case where each period is made up of N identical “structure” potential cells terminated by one different “impurity” cell. It is shown that the effect of the impurity is to re‐group the resonances of the corresponding “undoped” structure, in which all “impurity” cells are replaced by “structure” cells. The close relation to band splitting in the infinitely periodic limit is discussed.
Quantum Mechanical Properties of a Thin Cylinder. II. Magnetic Susceptibility and Electronic Specific Heat
Authors: Makar M. N. , Ahmed M. A. 
Published: July 2007

AbstractThe magnetic susceptibility, entropy, and electronic specific heat are calculated in the case of a hollow metallic cylinder placed in a magnetic field, both for weak and intermediate fields. Results are also presented for low and high temperatures. The obtained results show that the shell may acquire paramagnetic properties for some values of the field and diamagnetic properties for some other ones. However, this effect decays with increasing temperature and wall thickness. The electronic specific heat contributes strongly to the shell specific heat round a critical temperature while it becomes negligible near another temperature at which the specific heat due to lattice vibrations becomes dominant.
Static and Dynamic Behaviour of the Crystal Water Molecules in the Normal Phase of Deuterated Betaine Calciumchloride Dihydrate
Authors: Hacker U. , Holzer K.‐P. , Michel D. , Petersson J. 
Published: July 2007

AbstractThe static and dynamic behaviour of the deuterated crystal water molecules in the normal (N) phase of betaine calciumchloride dihydrate (BCCD) single crystals is investigated by means of quadrupolar perturbed 2H NMR. The temperature dependence both of the 2H NMR spectra and of the 2H spin‐lattice relaxation time 7i can be interpreted consistently by a thermally activated exchange process of the deuterons within the D2O molecule. At 170 K, under the condition of slow exchange, the electric field gradient (EFG) tensors of both deuterium sites are determined. From their principal axes and the quadrupole coupling constants information is derived about the structure of the C1D2O unit in BCCD in comparison with previous X‐ray studies.
Phase Sequence in Strongly Deuterated Betaine Arsenate
Authors: Almeida A. , Carvalho P. Simeão , Chaves M. R. , Klöpperpieper A. , Albers J. 
Published: July 2007

AbstractBetaine arsenate (BA) exhibits a structural phase transition at ≈ 119 K and becomes ferroelectric below this temperature. The deuteration changes drastically its properties and an antiferroelectric phase emerges between the paraelectric and the low temperature ferroelectric phase, for deuterium content higher than 77%. A previous work explained the transition sequence of BA and deuterated BA (DBA) on the basis of competitive interactions. A detailed experimental study of the pyroelectric and dielectric properties of DBA at zero field and under dc electric fields is reported. This study, carried out in DBA with deuterium content of 85%, reveals a new polar phase. The phase diagram shows the existence of a field induced ferroelectric phase and the experimental data obtained provide evidence for the role played by competitive interactions in DBA.
Luminescence Study of Na6MnCl8 and Na6MnBr8 Microcrystals in NaCl and NaBr Lattices
Authors: de Lucas M. C. Marco , Rodriguez F. , Moreno M. 
Published: July 2007

AbstractA detailed study of the luminescence and excitation spectra as well as of the lifetime (τ) on Na6MnX8 (X = Cl, Br) precipitates in the 300 to 2 K temperature range is made. In spite of the large distance between nearest Mn2+ ions (0.797 nm for Na6MnCl8), it is demonstrated that even at 2 K luminescence takes place at excitation traps after an exchange induced transfer between close Mn2+ ions. At variance to compounds like MnF2, only one trap (with depth of 350 and 480 cm−1 for X = Cl and Br, respectively) together with killers is mainly responsible for the observed temperature dependence of the luminescence. Aside from the inhomogeneous broadening of the emission band, the extrinsic character of the luminescence is underlined by the experimental Stokes shift observed at 10 K. The analysis of the bandwidth and the vibrational progressions on the 4T1g(G) band is perfectly explained in terms of coupling to the a1g mode. The increase of the Huang‐Rhys factor on passing from Na6MnCl8, S(a1g) = 5, to Na6MnBr8, S(a1g) = 8, is reasonably explained through a microscopic model. It is demonstrated that the lifetime‐temperature dependence is mainly governed by the overlap between the absorption and emission bands. This overlap is estimated subtracting the odd‐phonon contribution to the Stokes shift since phonon assistance is not required for excitation transfer through superexchange. The existence of Mn2+ −Mn2+ transfer down to 2 K is related to the perfect cubic symmetry of these compounds, and to a small coupling to the Jahn‐Teller eg mode. The different thermal shifts experienced by the luminescence and the excitation 4T1g(G) band are also discussed.
Lattice Dynamics of Chlorotrifluoromethane
Authors: Zeng W. Y. , Anderson A. 
Published: July 2007

AbstractA simple force constant model is applied to the vibrations of crystalline CClF3 at low temperatures. The model uses twelve adjustable parameters (six intermolecular and six intramolecular) to calculate the frequencies of nine lattice modes and eighteen components of internal modes. Good agreement with recent Raman and infrared spectra is obtained. Principal intermolecular interactions, between various pairs of halogen atoms, are identified. Intramolecular force constants are only slightly changed from their gas phase values.
Core and Valence Thermal Vibrations in Diamond, Silicon, and Germanium
Authors: Saravanan R. , Balamurugan P. , Mohanlal S. K. 
Published: July 2007

AbstractAn analysis is made using published X‐ray data, for the thermal vibrations in diamond, silicon, and germanium. The overall thermal vibration is split into core and valence contributions, because valence electrons can oscillate with different phase and amplitude than core electrons due to bond polarizability. Using indigenously developed computer programs the published data are analyzed. In the first phase, the overall Debye‐Waller factor of diamond, Si, and Ge together with scaling and extinction factors are refined using the method of least squares. In the second phase, the core and valence contributions of the harmonic temperature factor are evaluated. Finally, in the third phase, the core and valence contributions of the anharmonic temperature factor are evaluated. The error in the fitting procedure is less than 1% for Si and Ge and about 3% for diamond.
Surface Polaritons at the Interface of Two Anisotropie Crystals
Authors: Beletskii N. N. , Brukva A. N. , Nikolaeva T. N. , Cherkashin V. P. 
Published: July 2007

AbstractThe paper presents the results of theoretical and experimental investigations of phonon polaritons at the free surface of the uniaxial single crystal Al2O3 and for the three‐layer structure “vacuum‐uniaxial ZnO crystal‐uniaxial Al2O3”. The optical axes of the crystals are assumed to be normal to the interfaces of the media. The conditions of the existence of surface polaritons of different types are determined. It is shown that with the help of the attenuated total reflection technique (ATR) these polaritons could be used for the contactless determination of the film thickness as well as for nondamaging control of the main parameters of uniaxial crystals.
Determination of the True Metal‐Ligand Bond Lengths from the Optical Spectrum for Transition‐Metal Ions in Crystals
Authors: Zhao M. G. 
Published: July 2007

AbstractThe dependence of the optical spectrum of the Mn2 + −6F− cluster in crystals upon the true metal‐ligand (M‐L) bond length is studied by using a new refinement technique for the determination of the structure. Calculations show that the present theory gives a unified explanation for the d‐d transition spectra, the paramagnetic properties, and thermal expansion of Rbmnf3 and Kmgf3:Mn2 +.
Pancake Vortex Pinning by Defects in Strongly Anisotropic High‐Temperature Superconductors
Authors: Boiko J. , Majewski P. , Aldinger F. 
Published: July 2007

AbstractDefects of crystalline structures are potential pinning centres of the magnetic vortex dots (“pancake vortices”) within strongly anisotropic high‐Tc superconductors. The peculiarity of the interaction between the pancake vortex and various defects is analyzed and the values of the elementary pinning potential, Up, and that of the critical current density, Jc, are estimated.
Two‐Photon Absorption in an Indirect‐Gap Semiconductor Quantum Well System. I. Interband Transitions
Authors: Hassan A. R. 
Published: July 2007

AbstractPhonon‐assisted two‐photon interband transitions in an indirect‐band‐gap semiconductor layered quantum well (QW) and quantum well wire (QWW) are theoretically studied. The spectral dependence of the two‐photon absorption (TPA) coefficients α(1), α(2), α(3) in one‐dimensional (ID), 2D, and also 3D (bulk) systems, respectively, are found to vary according to (2ħω ± ħΩ − EG)β, where ħω(ħΩ) is the photon (phonon) energy and EG is the effective indirect gap. β takes the values 0, 1, 2, and 3 depending on the dimension of the system and the form of momentum matrix elements. The analytical expressions of the electron‐photon and electron‐phonon matrix elements in QW systems are given. The numerical calculation of the TPA coefficients α(1), α(2), and α(3) in Si0.5Ge0.5 shows that: α(1)(α(2)), for polarization parallel to the confinement directions, is four (two) orders of magnitude bigger than α(3) for allowed‐allowed transitions. Furthermore, α(1) is two orders of magnitude larger than α(2), for both photon polarizations with respect to the confinement directions in QW systems. This enhancement of α(1) over α(2) and α(3) is interpreted as due to the additional lateral quantum confinement of the carriers in QWW and also due to the intra‐subband momentum matrix elements.
Channeling Radiation in a Crystal Undergoing an Action of Ultrasonic or Electromagnetic Waves
Authors: Dedkov G. V. 
Published: July 2007

AbstractThe radiation emitted by channeled electrons and positrons in a crystal undergoing an action of ultrasonic (electromagnetic) waves is considered in quantum approximation. The most general crystal potential is shown to consist of two terms: the stationary and nonstationary ones both depending on the atomic displacements caused by the wave. As a result the peak positions and intensities of channeling radiation depend on the wave intensity, too. At resonance between one of the perturbation harmonics of the crystal potential and the proper particle transition the calculated radiation rate exceeds that one without wave by several orders.
Lattice Dynamics of Muscovite Layered Silicates
Authors: Gupta H. C. , Sinha M. M. , Rawat C. C. S. , Tripathi B. B. 
Published: July 2007

AbstractThe lattice dynamics of muscovite layered silicates along the finite wave vector direction is investigated. The calculated results are compared with available experimental results. The present angular force model gives a satisfactory picture of the phonons in complex structures like muscovites and their intercalates.
Electronic Excitations Localized in NaBr and RbI Crystals Near Vacancy Defects of Different Sizes
Authors: Vasilchenko E. , Sarmukhanov E. , Elango A. 
Published: July 2007

AbstractThe luminescence and excitation spectra of electronic excitations localized near a single anion vacancy (eα), a divacancy (ed), and a vacancy quartet (eq) are investigated at 4.2 K in deformed NaBr and RbI crystals. It is shown that the dissociation of eq into a VK and an electron‐vacancy complex occurs together with their radiative decay in NaBr, KBr, and RbI. Based on the spectral proximity of optical characteristics of eq and Ex luminescence, on the one hand, and eα and π luminescence, on the other, it is concluded that by their nature eq excitations represent weak off‐center and eα excitations strong off‐center configurations.
Dependence of the Electrical Resistivity on the Degree of Short‐Range Order in Multicomponent Solid Solutions
Authors: Yu Ge 
Published: July 2007

AbstractThe effect of short‐range order on the electrical resistivity in multicomponent solid solutions is studied by applying the model of Rossiter and Wells in which a spherical Fermi surface and s‐s scattering mechanism are assumed. For the description of the state of short‐range order in multicomponent systems a set of generalized Warren‐Cowley parameters αiXY are defined, based on the same assumptions that were used in the earlier treatments of binary alloys, a linear combination between the short‐range order induced resistivity and αiXY is obtained. The possibility of the experimental verification of the derived relationship is further discussed.