bluuebunny/crossref_metadata_2025 huggingface dataset:
An investigation of training activities and transfer of training in organizations
Authors: Saks Alan M. , Belcourt Monica
Published: November 2006

The purpose of this study was to investigate the extent to which organizations implement training activities for facilitating the transfer of training before, during, and after training and the relationship between these activities and the transfer of training across organizations.Training professionals from 150 organizations reported that 62%, 44%, and 34% of employees apply training material on the job immediately, six months, and one year after training. In addition, their organizations were significantly more likely to use training activities to facilitate transfer during training than either before or after training. Further, training activities before, during, and after training were significantly related to the transfer of training; however, activities in the work environment before and after training were more strongly related to transfer than activities during training. The practical and research implications of these findings are discussed for improving the transfer of training in organizations. © 2006 Wiley Periodicals, Inc.
A performance‐based, minimalist human resource management approach in business schools
Authors: Lorange Peter
Published: November 2006

This article examines the professorial human resource base in academic institutions. More specifically, we focus on professors in business schools. All academic institutions, business schools included, must have top‐quality faculty. Their drive for enhancing academic value creation, generating cutting‐edge research, leading teaching, and building strong interrelationships with students and executive participants fuels the success of the academic institution. Obviously, the other employees also are important.The administration must be outstanding, along with the research associates, finance staff, marketing team, and the like. Still, in order to contribute to the overall success of the academic institution, these other functions all depend on an outstanding professorial staff—they cannot create success alone. © 2006 Wiley Periodicals, Inc.
Can financial derivatives inform HRM? Lessons from Moneyball
Authors: Bryan Dick , Rafferty Michael
Published: November 2006

A comment on Richard Wolfe, Patrick M. Wright and Dennis L. Smart, Radical HRM Innovation and Competitive Advantage: The Moneyball Story. Human Resource Management, Spring 2006, Vol. 45, No. 1, pp. 111–145
Hydroclimatic controls on water balance and water level variability in Great Slave Lake
Authors: Gibson J. J. , Prowse T. D. , Peters D. L.
Published: November 2006

On average, 86% of riverine discharge to Great Slave Lake, Northwest Territories, Canada, was gauged during the period 1964–1998, offering an unprecedented opportunity to study and understand controls on water balance of a large northern lake at the headwaters of the Mackenzie River. A functional daily water balance model, incorporating measurements of riverine inflow, precipitation on the lake surface, evaporation, and riverine outflow was developed, which predicts the amplitude and frequency of annual water level fluctuations, and closes the water balance to within ± 6% for 28 of 35 years and ± 11% for the remaining 7 years, with an overall systematic error of + 2%. Annual water balance estimates for the period 1964–1998 reveal that about 74% of inflow into Great Slave Lake originates from the Peace‐Athabasca catchments that enter the lake via the Slave River, whereas 21% is derived from other catchments bordering Great Slave Lake, and 5% from precipitation on the lake surface. An estimated 94% of water losses occur by riverine outflow to the Mackenzie River and 6% by evaporation from the lake surface. The primary driving force behind water level fluctuations in Great Slave Lake, including the post‐regulation period following development of the W.A.C. Bennett Dam, is shown to be climate‐driven precipitation variability in the Peace‐Athabasca basins. A simple precipitation regression model is developed to simulate water level fluctuations in Great Slave Lake over the past 100 years. Copyright © 2006 John Wiley & Sons, Ltd.
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

This 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

Tributyltin (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

In 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

The 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

In 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

We 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

We 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

We 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

We 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

A 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

Electronic 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

The 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

We 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

Three 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

We 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

We 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

In 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

In 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

We 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

We 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

A 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)
Charge‐controlled nuclear polarization of a single InAs/GaAs quantum dot under optical pumping
Authors: Eble Benoît , Krebs Olivier , Lemaître Aristide , Kowalik Katarzyna , Kudelski Arkadiusz , Urbaszek Bernhard , Amand Thierry , Marie Xavier , Voisin Paul
Published: November 2006

We report on electron spin physics in a single charge‐tunable self‐assembled InAs/GaAs quantum dot. The hyperfine interaction between the optically oriented electron and nuclear spins leads to the polarization of the quantum dot nuclei. The sign of the resulting Overhauser‐shift depends on the trion state X + or X –, and remarkably its amplitude does not vanish in zero magnetic field. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimization of InAs/(Ga,In)As quantum dots in view of efficient emission at 1.5 µm
Authors: Hugues M. , Richter M. , Damilano B. , Chauveau J.‐M. , Duboz J.‐Y. , Massies J. , Wieck A. D.
Published: November 2006

InAs self‐organized quantum dots covered by low temperature (Ga,In)As layer with different thicknesses and indium contents have been grown on GaAs substrates by molecular beam epitaxy. The most efficient emission is obtained for islands covered by 5 nm thick Ga0.85In0.15As cap layer. A strong room temperature emission at 1.33 µm with a linewidth as narrow as 21 meV is observed. Moreover, the analysis of temperature dependent photoluminescence intensity indicates that the main quenching mechanism comes from carrier escape from the dots to the confined level of the quantum well formed by the cap layer and the wetting layer. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transitions between electron‐molecule states in electrostatic quantum dots
Authors: Maksym P. A. , Aoki H.
Published: November 2006

Intermediate spin states that occur in electrostatic dots in the magnetic field regime just beyond the maximum density droplet are investigated. The 5‐electron system is studied with exact diagonalization and group theory. The results indicate that the intermediate spin states are mixed symmetry states with a superposition of 5‐ and 4‐fold electron‐molecule configurations. A superposition of 5‐ and 4‐fold correlation functions is found to reproduce the exact mixed symmetry pair correlation function to around 2%. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pollen lipids attractive to honeybees
Authors: Lepage M. , Boch R.
Published: November 2006

Two substances attractive to honeybees have been isolated from mixed pollens. One is a pigment which was identified as a lutein ester, the other is a free fatty acid which chromatographed was identified as a C18 straight‐chain dienoic or trienoic acid.
Relative incorporation of linoleic and arachidonic acid in phospholipids and triglycerides of different rat tissues
Authors: Catala Angel , Brenner Rodolfo R.
Published: November 2006

Fat‐deficient rats were fed different amounts of methyl linoleate for increasing periods of time. The fatty acid composition of triglycerides and phospholipids of epididymal fat pad, epirenal fat depot, intestinal fat depot, liver, and the pool of heart, kidney, lungs and pancreas was determined. The distribution of the total amount of linoleic and arachidonic acid incorporated into phospholipids and triglycerides per rat was calculated. Phospholipids and triglycerides of depot tissues presented different fatty acid compositions.

Although the phospholipids of liver and the pool of heart, kidney, lung and pancreas specifically incorporated linoleic acid at the beginning they very rapidly attained a rather steady composition, whereas triglycerides went on incorporating the acid. The amount of linoleic acid incorporated into the phospholipids of depot tissues was rather small. The triglycerides undoubtedly contributed in the highest proportion to the total pool of linoleic acid. However, the highest proportion of arachidonic acid was found in the total pool of phospholipids.

The total amount of linoleic acid incorporated into the phospholipids was an approximately lineal function of the amount of phospholipids independent of period of administration and doses of methyl linoleate. Besides presenting two lineal functions of the amount of phospholipids, arachidonic acid showed a vertical increase coincident with a vertical decrease of the amount of eicosa‐5,8,11‐trienoic acid. At this period no change in the amount of the phospholipid was shown. This phenomenon is explaioned as a possible direct replacement of eicosatrienoic acid by arachidonic acid.
Fatty acid composition of milk phospholipids. II. Sheep, Indian buffalo and human milks
Authors: Morrison W. R. , Smith L. M.
Published: November 2006

Phospholipids were isolated from sheep, Indian buffalo, and human milks, and their fatty acid compositions determined by gas chromatography. The specific distributions of fatty acids in phosphatidyl cholines (PC) and phosphatidyl ethanolamines (PE) were determined after phospholipase A hydrolysis.

Fatty acid compositions and specific distributions were similar in sheep and buffalo milk phospholipids, and compared closely with those of bovine milk. Human milk phospholipids, particularly PE, contained much larger amounts of polyunsaturated acids, but negligible amounts of branchedchain acids. Palmitic and oleic acids were evenly distributed in human milk PC and PE, whereas they were preferentially located in the α′ position in PC and PE of ruminant milks.

The results are discussed in the context of current theories of lipid biosynthesis.
Circum‐annual changes in triglyceride fatty acids of bat brown adipose tissue
Authors: Paulsrud John R. , Dryer R. L.
Published: November 2006

A circum‐annual study of the fatty acids of brown adipose tissue triglycerides ofEptesicus fuscus has demonstrated a rhythmic pattern of change. This is seen as a reciprocal shift of the levels of oleic and linoleic acids. Oleic acid levels are lower during the summer months and higher in the winter months. Levels of palmitic and linoleic acids reach maximal values in midsummer and fall significantly during the winter.

Homogenates of brown adipose tissue produce more14CO2 from 1‐14C‐palmitic acid than from 1‐14C‐oleic acid when incubated at temperatures below 20C. The formation of14CO2 from either substrate was maximal in the neighborhood of 30C, and the temperature effect was enhanced by stimulation with DL‐carnitine.

It is proposed that the rhythmic change in brown adipose tissue triglyceride composition is a reflection of the different rates of fatty acid oxidation and the absence of normal food intake for extended periods of time.
The effect of a fat free diet on esterified monoenoic fatty acid isomers in rat tissues
Authors: Spence M. W.
Published: November 2006

Rats were maintained 120–140 days on a normal diet (group 1) or one deficient in fatty acids (group 2). Isomer composition was determined of monoenoic fatty acids (16∶1, 18∶1) isolated from total lipids of heart, kidney, lung, brain and lumbar fat, and from separated neutral lipids and phospholipids of heart and kidney. Group 1: The number of major isomers of C16∶1 and C18∶1 was similar in all tissues but their proportions varied in different tissues and types of lipid. Group 2: The proportions of 16∶1(n−7) increased and of other 16∶1 isomers decreased in all tissues; 18∶1(n−9) was increased at the expense of (n−7) in heart, to a lesser extent in kidney, and was little changed in lung, lumbar fat, or brain. The decrease in proportion of 18∶1(n−7) was greatest in heart‐muscle phospholipids. C20∶3 comprised 95% (n−9) and 5% (n−7) in heart and kidney lipids. The changes in group 2 probably represent the body's attempts to maintain lipids with the physical and chemical properties necessary to normal biological function.
The biosynthesis of cyclopropane and cyclopropene fatty acids in higher plants (Malvaceae)
Authors: Yano I. , Morris L. J. , Nichols B. W. , Jams A. T.
Published: November 2006

The biosynthesis of cyclopropane and cyclopropene fatty acids has been investigated in immature seeds, leaves and callus tissue cultures of several species of Malvaceae. Chemical characterization of labeled cyclopropane and cyclopropene fatty acids obtained from incubations withl‐[14CH3] methionine confirmed that the ring methylene group was derived from the methyl group of methionine. The variation with time in the distribution of radioactivity in the products of incubations with [14CH3] methionine and [2‐14C] acetate suggested that the pathway involved initial formation of dihydrosterculic acid from oleic acid with subsequent desaturation to sterculic acid and α‐oxidation to malvalic and dihydromalvalic acids. Direct evidence in favor of this pathway was provided by the conversion of [1‐14C] oleic acid to dihydrosterculic and sterculic acids and by the desaturation of [1‐14C] dihydrosterculic acid to sterculic acid, the first time that these processes have been demonstrated in higher plants. No conversion of [1‐14C] stearolic acid to sterculic acid could be obtained under the same conditions. The presence of an active fatty acid α‐oxidation system was demonstrated in the callus cultures.
Metabolism of odd‐numbered fatty acids inOchromonas danica
Authors: Gellerman J. L. , Schlenk H.
Published: November 2006

The lipids of the protozoon,Ochromonas danica, contain very small amounts of odd‐numbered fatty acids. Nevertheless the organism incorporates into its lipids odd‐ as well as evenumbered acids from the media. Unsaturated odd acids such as 9–17∶1 or 6,9,12–17∶3 were efficient substrates for elongation and desaturation in the proximal and the former acid also in the distal part of the chain. In contrast none of these conversions was observed with 7–17∶1, 10–17∶1 and 10,13–19∶2 acids, although these substrates were taken up by the organism. Elongation and desaturation of the proximal part of already unsaturated fatty acid chains appear to be subject to the same structural requirements inO. danica as in the rat, and the same effects apply to desaturation in the distal part of the chain.
The phospholipid and fatty acid composition of platelets in patients with primary defects of platelet function
Authors: Safrit Henry F. , Weiss Harvey J. , Phillips Gerald B.
Published: November 2006

Platelet phospholipid and fatty acid composition was determined in nine normal subjects and in 11 patients with primary defects in platelet function. Two of the patients had thrombasthenia (Glanzmann) and nine had various types of abnormalities in platelet aggregation and platelet factor 3 availability attributed to impairment of the platelet release reaction. The values observed for platelet lipids in the normal subjects were similar to those reported by others. Four of the patients with a disturbance in the platelet release reaction were in the same family and showed the same abnormal pattern of platelet lipid composition. Phospholipid analysis showed a decrease in the relative amount of phosphatidyl ethanolamine (PE) and an increase in lecithin. Abnormalities in fatty acids consisted of an increase in the relative amounts of 18∶1ω9, 20∶0 and 20∶1ω9 and a decrease in the 22∶4ω6+24∶1 fraction. Similar changes in PE and 18∶1ω9 were also observed in another patient with a similar defect in platelet function. In this patient the relative amount of platelet sphingomyelin was also increased. The platelet lipid composition in the other six patients and in one normal subject given aspirin was essentially normal.
2‐Alkylcyclobutanones from the radiolysis of triglycerides
Authors: Letellier P. R. , Nawar W. W.
Published: November 2006

A cyclic compound was isolated from the radiolytic products of each of the simple triglycerides containing C6, C8, C10, C12, C14, C16 and C18 fatty acids. In each case the compound was identified as the 2‐alkylcyclobutanone of the same carbon number as the precursor fatty acid. A mechanism is proposed for the production of these compounds which involves the formation of a six‐membered ring intermediate, cyclization and cleavage at the acyl‐oxy bond.
Oxidation of fatty acids by heat treated hemoproteins
Authors: Eriksson Caj E. , Olsson Pär A. , Svensson Svante G.
Published: November 2006

The hemoproteins catalase and peroxidase, after heat treatment which decreased their enzyme activities, became more efficient as heme catalysts of linoleic acid oxidation. These effects might be of importance for preservation and storage of food.
The metabolism of 1‐14C‐palmitic acid in the testis of the rat
Authors: Coniglio J. G. , Bridges R. B. , Aguilar H. , Zseltvay R. R.
Published: November 2006

The metabolism of 1‐14C‐palmitic acid was studied in rat testis at various intervals after intratesticular injection and after a 2 hr incubation period. Significant catabolism occurred as evidenced by production of14CO2 in both in vivo and in vitro experiments. Of the14C activity retained in the injected testis, less than 15% remained as free fatty acid after 2 hr and less than 5% by the end of 2 weeks. Activity of14C appeared in phosphatides faster than in the triglyceride fraction, and with time (1–2 weeks) the activity in phosphatides decreased relative to that in triglycerides. In phosphatides of these experiments ca. 80% of the14C was in the palmitic acid fraction and the balance predominantly (98%) in palmitate with the balance in stearate and oleate. By the first and second weeks almost half of the14C‐palmitate present in the testes had been newly synthesized from14C‐acetyl CoA resulting from oxidation of the administered 1‐14C‐palmitate. In the incubated samples the only fatty acid with14C activity in any lipid fraction was palmitate. In these experiments ca 90% of the14C was in the free fatty acid fraction, 7% in the phosphatides and 2% in the triglycerides.
Biosynthesis of protein relative to the accumulation of fat in the liver of EFA deficient rats
Authors: Fukazawa Toshio , Privett O. S.
Published: November 2006

Effect of an essential fatty acid (EFA) deficiency in the rat on the incorporation of leucine‐14C and glucosamine‐14C into serum and liver protein are reported. Weanling male rats of the Sprague‐Dawley strain were raised on a fat‐free diet for 10–12 weeks and then switched to diets supplemented with 10% corn oil or 10% hydrogenated coconut oil. Leucine‐14C or glucosamine‐14C was injected into the tail veins of the animals of each group. At selected intervals up to 120 min after the injections, the animals were sacrificed and the radioactivity of the liver and serum proteins was measured. The levels of triglyceride (TG) in the serum and the liver were also determined. Less radio‐activity was incorporated into the serum β‐lipoprotein (β‐LP) fraction of the hydrogenated coconut oil than the corn oil fed animals injected with leucine‐14C, but no differences were observed in the incorporation of radioactivity into the liver protein and both albumin and globulin fractions of the serum of these groups of animals. In the similar experiments with glucosamine‐14C less radioactivity was incorporated into the β‐LP fraction of the serum and into the smooth endoplasmic reticulum of the liver in the hydrogenated coconut oil (EFA deficient) than the corn oil fed animals. Time course studies also indicated that less radioactivity was incorporated into the β‐LP fraction than into the albumin and globulin fractions of the serum of the hydrogenated coconut oil group. These findings suggest that an EFA deficiency results in an impairment of the synthesis or release of lipoprotein.
Comparison of dialysis, thin layer and silicic acid column chromatography for prostaglandin isolation from biological material
Authors: Clausen J. , Srivastava K. C.
Published: November 2006

Chemical and biochemical methods assaying the total content of neutral lipids during some conventional procedures for purification and isolation of prostaglandins from biological fluids revealed all fractions to be contaminated with fatty acids, cholesterol, cholesterol esters, tri‐, di‐ and/or mono‐glycerides. It was demonstrated that it was not possible to make pure prostaglandin fractions by simple dialysis. On the basis of these findings a new preparative schedule involving either dialysis or column chromatography on silicic acid, combined with preparative thin layer chromatography, made it possible to isolate substantially pure PGE2 from a synthetic biological system involving arachidonic acid as a precursor and the microsomal synthesizing system from sheep vesicular glands.

Sheep vesicular glands have been used for biosynthesis of prostaglandins (PG) (1). For the study of the metabolism of various prostaglandins, labeled PGE1 has been prepared from 8, 11, 14‐eicosatrienoic acid labeled at various positions (2). Recently a method employing arachidonic acid and sheep vesicular glands for the formation of PGE2 has been patented. The method claims a high purity (98%) with quick recovery of PGE2 from the incubation mixture. The essential feature of the method is the use of a dialysis step which is said to be superior to the time‐consuming chromatographic procedures (3). In our recent studies on the metabolism of essential fatty acids, we have found it impossible to prepare chemically pure prostaglandins by the above mentioned methods, since cholesterol, cholesterol esters, fatty acids and glycerides were found to contaminate the final products. The present paper therefore gives some data on these contaminants, and on this basis a new approach to the isolation of chemically pure prostaglandin (PGE2) has been developed.
The stereochemistry of enzymic hydration and of chemical cleavage of D‐(+)‐cis‐12,13‐epoxyoleic acid (Vernolic acid)
Authors: Morris L. J. , Crouchman M. L.
Published: November 2006

The absolute optical configurations of (+)‐threo‐12,13‐dihydroxyoleic acid, derived by enzymic hydration of endogenous vernolic acid in crushedVernonia anthelmintica seed, and of (−)‐threo‐12,13‐dihydroxyoleic acid, derived by acetolysis‐hydrolysis of vernolic acid, have been determined. The absolute configuration of the (+)‐enantiomer is L‐12,D‐13‐dihydroxyoleic acid and, as the parent vernolic acid is known to be D‐12,D‐13‐epoxyoleic acid, the stereochemistry of the enzymic hydration is thus shown to involve attack by hydroxyl at the 12 position with inversion at that position. Chemical cleavage of vernolic acid, on the other hand, involves preferential nucleophilic attack, with inversion, at the 13 position.
Labeling of liver and plasma lecithins after injection of 1–2‐14C‐2‐dimethylaminoethanol and14C‐L‐methionine‐methyl to choline deficient rats
Authors: Lombardi B. , Pani P. , Schlunk F. F. , Shi‐hua Chen
Published: November 2006

Groups of rats were fed a choline‐deficient (CD) or a choline‐supplemented (CS) diet for 15 hr. Labeling of liver and plasma cephalins and lecithins was followed with time after injection of14C‐L‐methionine‐methyl or 1–2‐14C‐2‐dimethylaminoethanol, either alone or together with3H‐S‐adenosyl‐L‐methionine‐methyl. A reduced concentration of liver and plasma lecithins was found in CD rats. In the same animals, labeling of the phospholipid fractions was considerably greater and faster than in CS rats. Administration of choline to rats previously fed the CD diet resulted in both an increased concentration of liver and plasma lecithins and a reduction in the labeling of liver and plasma lecithins to levels seen in control rats. These results suggest that in CD rats, while the overall synthesis of lecithins may be reduced due to insufficient availability of choline, the synthesis of lecithins via stepwise methylation of cephalins may be increased.