bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of in vitro oxygen concentrations on preimplantation embryo development, gene expression and production of hanwoo calves following embryo transfer
Authors: Rho Gyu‐Jin , S Balasubramanian , Kim Dong‐Sik , Son Woo‐Jin , Cho Sang‐Rae , Kim Jung‐Gon , B Mohana kumar , Choe Sang‐Young 
Published: November 2006

AbstractThis study evaluated the effects of two different oxygen (O2) concentrations on in vitro embryo development, embryo quality, and gene expression and the in vivo development following embryos transfer to recipients of natural and synchronized estrus in bovines. Cumulus oocyte complexes were in vitro matured in TCM199 supplemented with FSH (10 µg/ml), LH (10 µg/ml), and 10% (v/v) FBS. Presumptive zygotes were cultured in SOF medium either under 5% (low) or 20% (high) O2 in air. Cleavage rates did not differ between groups. Blastocyst and hatched blastocyst development in 5% O2 were significantly (P < 0.05) higher than in 20% O2. Total cell number of in vivo blastocyst was significantly (P < 0.05) higher than that of in vitro blastocyst. ICM ratio and apoptosis of in vivo blastocyst were significantly (P < 0.05) lower than that of in vitro blastocyst. Using real time PCR, we have found that for the set of genes (GLUT‐1, MnSOD, VEGF, Bax, and Bcl‐2) analyzed, there were differences in mRNA expression between in vitro produced (IVP) and in vivo produced embryos. Interestingly, the abundance of transcript for IFN‐τ in IVP embryos produced under 5% O2 concentration was similar to in vivo counterparts. The pregnancy and twin rates of natural recipients were significantly (P < 0.05) higher than those of synchronized counterparts. No significant difference in the offspring sex was observed. In conclusion, low (5%) O2 concentration during IVC was beneficial for enhancing the embryo quality and recipients of natural estrus were more suitable than synchronized estrus for stable production of Hanwoo calves. Mol. Reprod. Dev. 74: 486–496, 2007. © 2006 Wiley‐Liss, Inc.
In utero exposure to tributyltin alters the expression of e‐cadherin and localization of claudin‐1 in intercellular junctions of the rat ventral prostate
Authors: Barthelemy Johanna , Adeeko Adedayo , Robaire Bernard , Cyr Daniel G. 
Published: November 2006

AbstractTributyltin (TBT) is an environmental contaminant, exhibiting well‐established toxicity to reproductive systems in aquatic organisms. Little information exists regarding the effects of TBT on mammalian reproduction. Cellular junctions are crucial for sperm development and maturation. Intercellular tight junctions are formed by transmembrane proteins such as claudins (Cldns), while the formation of tight junctions involves signaling components of adhering junctions, comprised of cadherins. The objectives of this study were to determine the effects of in utero exposure to TBT on the rat ventral prostate. Pregnant Sprague–Dawley rats were given doses of TBT (2.5, 10, or 20 mg/kg) throughout gestation and sacrificed at Day 91. Ventral prostate weights of TBT‐treated rats were decreased in all treatment groups. Results of gene expression macro‐array analysis indicated that numerous genes related to cellular adhesion and cell polarity were affected. Cldn‐1 mRNA levels decreased after exposure to TBT. Cldn‐1 was immunolocalized to the apical lateral margins of adjacent prostatic epithelial cells in controls, but was increasingly dispersed along the lateral plasma membrane with increasing TBT dose, suggesting that the targeting of Cldn‐1 or its localization to tight junctions was altered as a result of fetal TBT exposure. E‐cadherin mRNA levels and immunolocalization were decreased in a dose‐dependent manner. These data indicate that in utero TBT exposure results in permanent alterations in ventral prostate and that these are associated with alterations in the expression and distribution of cell adhesion and tight junctional proteins. Mol. Reprod. Dev. 74: 455–467, 2007. © 2006 Wiley‐Liss, Inc.
Bifurcation and second‐order work in geomaterials
Authors: Nicot François , Darve Félix , Dat Vu Khoa Huynh 
Published: November 2006

AbstractIn this paper, the ability of a material rate‐independent system to evolve toward another mechanical state from an equilibrium configuration, with no change in the control parameters, is investigated. From a mechanical point of view, this means that the system can spontaneously develop kinetic energy with no external disturbance from an equilibrium state, which corresponds to a particular case of bifurcation. The existence of both conjugate incremental strain and stress such that the second‐order work vanishes is established as a necessary and sufficient condition for the appearance of this bifurcation phenomenon. It is proved that this fundamental result is independent of the constitutive relation of the rate‐independent material considered. Then the case of homogeneous loading paths is investigated, and, as an illustration, the subsequent results are applied to interpret the well‐known liquefaction observed under isochoric triaxial loading conditions with loose granular materials. Copyright © 2006 John Wiley & Sons, Ltd.
Non‐aqueous reverse micelles media for the SNAr reaction between 1‐fluoro‐2,4‐dinitrobenzene and piperidine
Authors: Correa N. Mariano , Durantini Edgardo N. , Silber Juana J. 
Published: November 2006

AbstractThe kinetics of the nucleophilic aromatic substitution (SNAr) reaction between 1‐fluoro‐2,4‐ dinitrobenzene (FDNB) and piperidine (PIP) in ethylene glycol (EG)/ sodium bis (2‐ethyl‐1‐hexyl) sulfosuccinate (AOT)/n‐heptane and dimethylformamide (DMF)/AOT/n‐heptane non‐aqueous reverse micelle systems is reported. EG and DMF were used as models for hydrogen bond donor (HBD) and non‐hydrogen bond donor (non‐HBD) polar solvents, respectively. The reaction was found not to be base catalyzed in these media. A mechanism to rationalize the kinetic results is proposed in which both reactants may be distributed between the two environments. The distribution constants of FDNB between the organic and each micellar pseudophases were determined by an independent fluorescence method. These results were used to evaluate the amine distribution constant and the intrinsic second‐order rate coefficient of the SNAr reaction in the interface. The reaction was also studied in the pure solvents EG and DMF for comparison. The results in EG/AOT/n‐heptane at Ws = 2 give similar kinetic profiles than in water/AOT/n‐hexane at W = 10. With these HBD solvents, the interface saturation by the substrate is reached at around the same value of [AOT] and the intrinsic second‐order rate coefficient in the interface, k′b, has comparable values. On the other hand, when DMF is used as a polar non‐HBD solvent, the intrinsic second‐order rate constant increases by a factor of about 200 as compared to the values obtained using HBD solvents as a polar core. It is concluded that higher catalytic power is obtained when non‐HBD solvents are used as polar solvent in the micelle interior. Copyright © 2006 John Wiley & Sons, Ltd.
Quantum dots as fluorescent bio‐labels in cancer diagnostic
Authors: Farias Patrícia M. A. , Santos Beate S. , Menezes Frederico D. , Ferreira Ricardo , Fontes Adriana , Carvalho Hernandes F. , Romão Luciana , Moura‐Neto Vivaldo , Amaral Jane C. O. F. , Cesar Carlos L. , Figueiredo Regina C. B. Q. , Lorenzato Felipe R. B. 
Published: November 2006

AbstractIn this work we present and discuss some results concerning the application of colloidal semiconductor quantum dots for cancer diagnostic. We have prepared and applied different core‐shell semiconductor quantum dots such as Cadmium Teluride‐Cadmium Sulfide (CdTe‐CdS) and Cadmium Sulfide –Cadmium Hydroxide (CdS/Cd(OH)2). For the purpose of diagnostic with living cells, the CdS/Cd(OH)2 presented best results, maintaining high levels of luminescence as well high stability in biological media. The quantum dots were obtained in aqueous medium, by reacting Cd2+ and S2– in the presence of sodium polyphosphate as the stabilizing agent. Subsequent surface passivation with Cd(OH)2 was carried out to improve luminescence. At a pH of 7,2 the quantum dots were functionalized with a 0.01% glutaraldehyde solution and then, incubated with living healthy and neoplastic cells (glial, glioblastoms and cervical) and tissues (breast) in culture medium. Tissue and cell staining were evaluated by the laser scanning confocal microscopy. Fluorescence Microscopy was used as a primary tool in order to explore the labeling of the samples. The procedure presented in this work, shown to be very efficient as a potential tool for fast and precise cancer diagnostic. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
1.3 µm emission from InAs/GaAs quantum dots
Authors: Kuldová K. , Křápek V. , Hospodková A. , Oswald J. , Pangrác J. , Melichar K. , Hulicius E. , Potemski M. , Humlíček J. 
Published: November 2006

AbstractWe report here the results of our photoluminescence study of a series of single quantum dot layer structures containing InxGa1–xAs strain reducing layers with different In concentration (from 0% to 29%), prepared by low pressure metal organic vapour phase epitaxy. These structures display a strong red shift of photoluminescence maxima from 1.25 μm to 1.45 μm at 300 K with increased In content in the ternary layer. The origin of the observed transitions has been explained using magnetophotoluminescence measurements and photoluminescence measurements for different pumping intensities at low temperature. Optical transition energies were calculated using a simple single‐band effective mass model with energy‐dependent effective mass. Comparing the calculated and measured energies, we can determine the thickness of the wetting layer and the sizes of the dots. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Resonant Raman scattering in InGaAs/AlAs quantum dots
Authors: Milekhin Alexander , Toropov Alexander , Bakarov Alexander , Schulze Steffen , Zahn Dietrich 
Published: November 2006

AbstractWe report resonant Raman scattering from InGaAs/AlAs quantum dots with indium content x = 0.3 ÷ 1. The first order Raman spectra reveal resonant behaviour selective to a quantum dot size. Up to third‐order multi‐phonon processes have been observed in the quantum dot structure. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical characteristics of lowly strained GaInAs quantum dots
Authors: Löffler A. , Poloczek P. , Sęk G. , Misiewicz J. , Reithmaier J. P. , Forchel A. 
Published: November 2006

AbstractWe have investigated the optical properties of lowly strained GaInAs quantum dots (QDs). The structures were grown for a constant nominal GaInAs layer thickness but varying content (strain) from below to far above the critical thickness conditions. In order to investigate the properties of such an uncommon QD system, photoreflectance (PR) and photoluminescence, combined with scanning electron microscopy, have been used. Optical transitions connected with the ternary layer have been observed and followed from the lowest content quantum well case through the transformation into 3D islands on the wetting layer (WL) and a coexistence of the QD‐related and WL‐related transitions. Due to the observation of both heavy hole and light hole related transitions in PR spectra, the thickness of the wetting layer versus changed indium content could be determined by comparing the experimental data with the results of the effective mass envelope function calculations. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spin polarization in a single InAs/InP quantum dot
Authors: Sheng Weidong , Hawrylak Pawel 
Published: November 2006

AbstractWe report on a theoretical study of the spin properties of electrons and holes in a single InAs/InP selfassembled quantum dot by means of an empirical tight‐binding method. When the magnetic field is varied from the Faraday to Voigt configuration, electrons and holes are found to exhibit different spin polarization: the electron spin is found to follow the direction of the magnetic field while the hole spin is frozen along the growth direction of the dot. The frozen spin of holes is attributed to the dominant heavy‐hole component in the hole states, which also leads to a zero in‐plane g factor of holes. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Symmetry based calculation of electronic structure and intraband absorption in GaN/AlN hexagonal quantum dot superlattices
Authors: Vukmirović Nenad , Ikonić Zoran , Indjin Dragan , Harrison Paul 
Published: November 2006

AbstractA symmetry based method for the efficient calculation of single‐particle states in hexagonally symmetric GaN/AlN quantum dots within the framework of a k · p model is presented. The envelope functions are expanded into a plane wave basis on a hexagonal lattice and the group projector method is used to adapt the basis to exploit the symmetry, resulting in block diagonalization of the corresponding Hamiltonian matrix into six matrices and classification of the states by the quantum number of total quasi‐angular momentum. The method is applied to the calculation of the electron and hole energy levels in a quantum dot superlattice and the intraband optical absorption matrix elements. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microscopic tight‐binding description for electronic and optical properties of InN/GaN quantum dots
Authors: Schulz S. , Baer N. , Schumacher S. , Gartner P. , Jahnke F. , Czycholl G. 
Published: November 2006

AbstractElectronic and optical properties of self‐assembled InN/GaN quantum dots are investigated by use of a tightbinding model combined with a configuration interaction calculation. Dipole and Coulomb matrix elements are calculated from the single‐particle wavefunctions which fully include the atomistic wurtzite structure of the low‐dimensional heterostructure and serve as input parameters for the calculation of optical properties. We discuss in particular the influence of the internal electric field on the multi‐exciton spectra. Dark exciton and biexciton ground‐states are found for small quantum dots. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Kondo spin splitting in quantum dots with ferromagnetic leads
Authors: Aguiar Hualde J. M. , Chiappe G. , Anda E. V. 
Published: November 2006

AbstractThe splitting of the Kondo Resonance (KR) in a quantum dot (QD) connected to ferromagnetic leads is studied using a new Slave Boson formulation. We show that the KR is splitted into two resonances out of the Fermi level. The splitting can be controlled by the application of a magnetic field in the QD. While this magnetic field does not modify the magnetism of the leads, it can restore the KR at the Fermi level. When the magnetization is strong enough, it's not possible to recover the KR. In addition, selective spin transport across the QD can be achieved by tuning the magnetic field. This effect is a consequence of the asymmetric Kondo splitting produced by the magnetic leads. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
CdS‐Cd(OH)2 core shell quantum dots functionalized with Concanavalin A lectin for recognition of mammary tumors
Authors: Santos Beate S. , de Farias Patrícia M. A. , de Menezes Frederico D. , de C. Ferreira Ricardo , Júnior Severino A. , Figueiredo Regina C. B. Q. , de Carvalho Luiz B. , Beltrão Eduardo I. C. 
Published: November 2006

AbstractWe report the use of CdS/Cd(OH)2 quantum dots functionalized with glutaraldehyde and conjugated to concanavalin‐A (Con‐A) lectin to investigate cell alterations regarding carbohydrate profile in human mammary tissues diagnosed as fibroadenoma (benigne tumor). The Con‐A lectin is a biomolecule which binds specifically to glucose/mannose residues present in the cellular membrane. These bioconjugated‐particles were incubated with tissue sections of normal and to Fibroadenoma, a benign type of mammary tumor. The tissue sections were deparafinized, hydrated in graded alcohol and treated with a solution of Evans Blue in order to avoid autofluorescence. The fluorescence intensity of QD‐Con‐A stained tissues showed different patterns which reflect the carbohydrate expression of glucose/mannose in fibroadenoma when compared to the detection of the normal carbohydrate expression. The pattern of inespecific labeling of the tissues with glutharaldehyde functionalized CdS/Cd(OH)2 quantum dots is compared to the targeting driven by the Con‐A lectin. The preliminary findings reported here support the use of CdS/Cd(OH)2 quantum dots as specific probes of cellular alterations possibiliting their use in diagnostics. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High‐gain low‐threshold InAs/InGaAs/GaAs quantum dot lasers emitting around 1300 nm
Authors: Salhi A. , Martiradonna L. , Fortunato L. , Tasco V. , Visimberga G. , Cingolani R. , Passaseo A. , De Vittorio M. 
Published: November 2006

AbstractThree semiconductor laser structures containing 1, 3 and 5 layers of self organized InAs/InGaAs/GaAs quantum dots (QDs) have been grown by Molecular Beam Epitaxy. Broad area lasers were processed from the grown wafers and tested. These structures show a linear increase of the modal gain with the number of QDs layers with an average modal gain per QDs layer of ∼5 cm–1. A maximum modal gain of 25 cm–1 was obtained at room temperature (RT) from the sample containing 5 layers of QDs. A transparency current density and a low internal loss value of ∼5.5 A/cm2 per QD layer and 1.5 cm–1 were deduced respectively. For an infinite cavity length a minimum threshold current density of ∼9 A/cm2 per QD layer was inferred. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High resolution photocurrent‐spectroscopy of a single quantum dot
Authors: Ester Patrick , Stufler Stefan , Michaelis de Vasconcellos Steffen , Bichler Max , Zrenner Artur 
Published: November 2006

AbstractWe report on high resolution photocurrent spectroscopy of a single quantum dot. Our attention applies to the two‐level character of a single InGaAs/GaAs quantum dot, defined by the ground state exciton. With high resolution photocurrent spectroscopy we analyze the behaviour of a single quantum dot under cw‐excitation. Experiments include linewidth, powerbroadening and saturation analysis. In the limit of low optical excitation we observe a ground state line width down to 4 µeV. With increasing excitation intensities the line width shows a characteristic power broadening. This effect is a direct consequence of the saturation of the absorption in a two‐level system under conditions of high excitation intensities. Using the high resolution we are able to measure the excitonic fine structure splitting in the ground state. The results of the cw‐excitation experiments indicate as an almost perfect quantum mechanical two‐level system. These experiments are essential for coherent manipulation of single quantum dots, important for possible applications in quantum information processing. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Temperature dependence of the photoluminescence of single GaAs/AlGaAs concentric quantum ring structure
Authors: Bonfanti M. , Sanguinetti S. , Mano T. , Kuroda T. , Gurioli M. , Abbarchi M. , Grilli E. , Koguchi N. 
Published: November 2006

AbstractWe present the temperature dependence of the photoluminescence emission of single concentric quantum rings. The two rings which form the nanostructure show a decoupled recombination kinetics in the whole temperature range. The emission is characterized by a doublet. The emission linewidth, which is already larger than 1 meV at low temperatures and increases as the temperature raises, is dominated by the thermal activation of carriers to higher excited states. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Recombination lifetime of single GaAs/AlGaAs quantum dots
Authors: Abbarchi M. , Gurioli M. , Sanguinetti S. , Zamfirescu M. , Vinattieri A. , Koguchi N. 
Published: November 2006

AbstractIn this contribution we experimentally demonstrate, by means of time resolved microphotoluminescence on single GaAs quantum dot (QD), that the lifetime is reduced when decreasing the dot size. The samples are grown by modified droplet epitaxy and are strain free nanocrystals. The analysis of the recombination kinetics as a function of the excitation power allows us to resolve the exciton and biexciton contribution, leading to a clear interpretation of the experimental data. The broad inhomogeneous size distribution of QDs grown by droplet epitaxy (O. Stier et al., Phys. Rev. B 59, 5688 (1999), [4]) is used to investigate QDs of different size in a single sample. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Temperature dependence of photoluminescence from CdS nanoclusters formed in the matrix of Langmuir‐Blodgett film
Authors: Bagaev E. A. , Zhuravlev K. S. , Sveshnikova L. L. 
Published: November 2006

AbstractIn this paper photoluminescence from CdS nanoclusters formed in the matrix of Langmuir‐Blodgett film has been investigated in the temperature range 5‐300 K. The photoluminescence spectrum of the nanoclusters at 300 K consists of two bands at 2.9 and 2.1 eV. Temperature dependence of the high‐energy band maximum deviates from the dependence of the energy bandgap of bulk CdS. The integrated PL intensity of this band decreases with increasing temperature up to 75 K, grows in a temperature range 150‐230 K, and rapidly falls at temperatures higher 230 K. The experimental data have been explained within the framework of a model of recombination of carriers considering carrier transport between CdS nanoclusters. An energy of electron traps and activation energies of nonradiative recombination have been estimated to be about 120, 4 and 100 meV, respectively. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transmission phases and Fano resonances in carrier transport through a few‐electron quasi‐1D quantum dot
Authors: Bertoni Andrea , Goldoni Guido 
Published: November 2006

AbstractWe use a novel approach, allowing the inclusion of particle‐particle correlation in the calculation of current‐carrying states in open systems, to compute the exact transmission amplitude of an electron crossing a quasi‐1D quantum dot. The electron state antisymmetry is accounted for by means of a proper choice of the boundary conditions. Fano resonances, showing the peculiar phase discontinuity, are found. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantum interferences of a single quantum dot in the case of detuning
Authors: Michaelis de Vasconcellos Steffen , Stufler Stefan , Wegner Sven‐Ake , Ester Patrick , Zrenner Artur , Bichler Max 
Published: November 2006

AbstractWe report on highly phase sensitive measurements with a slightly detuned excitation of a quantum mechanical two‐level system. It is formed by the single exciton ground state of a single quantum dot, which is incorporated in a n‐i‐Schottky diode. We excited the two‐level system by two partly overlapping laser pulses with variable phase shift. To investigate the properties of the quantum system we determine its occupancy by measuring the photocurrent. The experimental data is compared to a numerical simulation of the system. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A novel approach for the growth of InGaN quantum dots
Authors: Yamaguchi T. , Sebald K. , Lohmeyer H. , Gangopadhyay S. , Falta J. , Gutowski J. , Figge S. , Hommel D. 
Published: November 2006

AbstractA novel two‐step growth method for creating InGaN quantum dots (QDs) was developed by using a combination of an Inx Ga1–x N nucleation layer with a platelet structure and an Iny Ga1–y N formation layer with an indium content lower than that of the Inx Ga1–x N nucleation layer. The realized QDs were investigated by micro‐photoluminescence measurements. We observed sharp emission lines at 4 K with a spectral width down to the spectral resolution limit of the experimental setup of 0.17 meV. This growth concept is discussed in comparison with conventional growth methods. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)