bluuebunny/crossref_metadata_2025_split huggingface dataset:
Salinity, Inorganic Nutrients, and Primary Production in a Shallow Coastal Inlet in the Southern Baltic Sea (Nordrügenschen Bodden) Results from Long‐Term Observations (1960–1989)
Authors: Hübel Helmut , Wolff Christiane , Meyer‐Reil Lutz‐Arend 
Published: February 2007

AbstractThe Nordrügenschen Bodden waters are a shallow coastal inlet of the Southern Baltic Sea consisting of individual basins, some of which are joined only via small connections. The Bodden are characterized by pronounced horizontal gradients in hydrographical, chemical and biological parameters. Whereas concentrations of inorganic nutrients increase, salinity decreases with increasing distance from the connection to the Baltic Sea. Between 1960 and 1989 long‐term variations of salinity, inorganic nutrients (ammonium, nitrate, phosphate), Secchi disk visibility, and planktonic primary production were monitored at 6 locations throughout the Bodden. The gradients were most pronounced during the first period of observation (1960–1963). Between 1960 and 1985 concentrations of inorganic nutrients in the adjacent Arkona Sea increased up to values several times higher than the previous concentrations. This increased nutrient load in the Baltic Sea was reflected by higher nutrient concentrations and higher primary production in the outer and central parts of the Nordrügenschen Bodden. Between 1963 and 1965 the shipping channel between the outer (Libben) and the inner part (Großer Jasmunder Bodden) of the Bodden chain was dredged. This led to an improvement of water exchange between the Baltic Sea and the Bodden, resulting in a significant reduction of the gradients of chemical and biological parameters. Whereas salinity and Secchi disk visibility increased, inorganic nutrients, and primary production decreased. This was most obvious in the inner parts of the Bodden where the water quality was improved. The trophic status of the Kleiner Jasmunder Bodden is still worrying. This Bodden represents the innermost part of the Nordrügenschen Bodden connected with the Großer Jasmunder Bodden only via a small flood gate. Unless the water exchange is drastically improved, the Kleiner Jasmunder Bodden will retain its hypertrophic status in the longer term. The future development of the trophic status of the Bodden is discussed.
Subcellular localization of ankyrin repeats cofactor‐1 regulates its corepressor activity
Authors: Zhang Aihua , Li Chia‐Wei , Tsai Shih‐Chieh , Chen J. Don 
Published: February 2007

AbstractThe ankyrin repeats cofactor‐1 (ANCO‐1) was recently identified as a novel nuclear receptor corepressor that regulates receptor‐mediated transcription through interactions with p160 coactivators and histone deacetylases. Interestingly, exogenously expressed ANCO‐1 is localized at distinct subnuclear domains. The relevance of these subnuclear domains and the mechanisms of nucleocytoplasmic translocation of ANCO‐1 have not been determined. We report here the identification of an N‐terminal signaling motif that is essential for both nuclear/subnuclear localization and transcription corepressor function of ANCO‐1. This N‐terminal motif at residues 80–86 of ANCO‐1 constitutes a classical nuclear localization signal (NLS1). Disruption of NLS1 causes complete cytoplasmic accumulation of the full‐length ANCO‐1, and abolishes its corepressor function on receptor‐mediated transcription. A second NLS (NLS2) is found at the C‐terminal residues 2384–2390; however, its disruption abolishes only nuclear localization of isolated C‐terminal fragments. We also identify a leucine‐rich nuclear export signal (NES) at residues 2415–2424 of ANCO‐1, and show that both the NLSs and NES sequences are capable of mediating nuclear import and export of heterologous protein, respectively. In addition, attachment of the NES sequence to a transcription factor impairs its activation function. These results suggest that ANCO‐1 subnuclear localization is regulated by both nuclear import and export signals, and that proper subcellular localization of ANCO‐1 is essential for its corepressor function. J. Cell. Biochem. 101:1301–1315, 2007. © 2007 Wiley‐Liss, Inc.
Characteristics of US drought and pluvials from a high‐resolution spatial dataset
Authors: Kangas Ryan S. , Brown Timothy J. 
Published: February 2007

AbstractAnomalous precipitation can be a devastating natural disaster having significant impacts on economies, society and the environment. This study examines the spatial and temporal characteristics of anomalous precipitation throughout the United States to obtain a greater understanding of drought/pluvial regimes, including intensity, duration and spatial coverage based on a high‐resolution precipitation dataset. With the help of the parameter‐elevation regression on independent slopes model (PRISM), approximately 4 km data for the United States is used to construct the Palmer drought severity index (PDSI) and the standardized precipitation index (SPI) for the period 1895–2003. Increased resolution from the PRISM dataset shows that drought/pluvial areas are not as homogeneous as seen in previous studies based on climate divisions and larger scales. While size, duration and locations of drought/pluvial events are influenced by the index used, the largest annual drought/pluvial events occur more frequently in the central United States, with a higher percentage of extreme values occurring in the western portion of the country. Four large pluvial events have occurred in the United States during the study period, with three of these having occurred during the past 30 years. Copyright © 2007 Royal Meteorological Society
Design and Synthesis of Thermally Curable Polymers with Benzoxazine Functionalities
Authors: Kiskan Baris , Gacal Burcin , Tasdelen M. Atilla , Colak Demet , Yagci Yusuf 
Published: February 2007

AbstractIn this paper, synthetic strategies for the preparation of structurally different polymers, namely polystyrene (PSt), poly(ε‐caprolactone) (PCL), poly(propyleneoxide) (PPO), poly(methyl methacrylate) (PMMA), and poly(styrene‐alt‐ maleimide) (PSt‐alt‐MI) with thermally curable benzoxazine groups have been outlined. Specifically, these groups were incorporated into PSt and PCL by using two controlled polymerization methods, namely Atom Transfer Radical Polymerization (ATRP) and Ring Opening Polymerization (ROP), respectively. Modification of linear and branched poly(propylene amine)s via Mannich reaction yields the corresponding benzoxazine functional PPOs. The photoinitiated polymerization of olefinic monomers such as methyl methacrylate by using benzoxazines as hydrogen donor in conjunction with aromatic carbonyl compounds is another suitable method for the desired functionalization. Moreover, benzoxazine substituted maleimide was copolymerized with styrene to yield perfectly alternating benzoxazine functional copolymers (PSt‐alt‐MI).
Immobilization of Zirconocene into Silica Prepared by Non‐Hydrolytic Sol‐Gel Method
Authors: Fisch Adriano , Petry Cristiane F. , Pozebon Dirce , Stedile Fernanda C. , Cardozo Nilo S. M. , Secchi Argimiro R. , dos Santos João H. Z. 
Published: February 2007

AbstractConcomitant immobilization of zirconocene (Cp2ZrCl2) into a silica matrix was performed during the SiO2 synthesis through non‐hydrolytic sol‐gel method. Two different routes, varying the SiCl4:Si(OEt)4 ratio were evaluated in terms of zirconocene content and catalyst activity in ethylene polymerization, using methylaluminoxane (MAO) as cocatalyst. The catalysts were characterized by Rutherford backscattering spectrometry, Fourier transform infrared spectroscopy, diffuse reflectance spectroscopy, scanning electron microscopy and X‐ray dispersive spectroscopy. The zirconocene content laid between 0.60 and 1.02 wt.% Zr/SiO2, depending upon the components ratio employed in the sol‐gel synthesis. Catalyst grains presented of irregular shape (20–100 µm size) and zirconocene distribution was not uniform. Both routes led to supported catalysts active in ethylene polymerization. Catalyst activity was intermediate between that exhibited by the homogeneous and the grafted zirconocene on silica. Resulting polyethylenes presented narrow molecular weight distribution and molecular weight slightly higher than that observed in the case of polymer produced with the homogeneous system.
Modification of Model Ethylene‐Butene Copolymers Using Gamma Radiation and an Organic Peroxide
Authors: Andreucetti Noemí , Pérez Javier , Failla Marcelo , Vallés Enrique 
Published: February 2007

AbstractWell‐characterized linear ethylene‐butene copolymers with polydispersities lower than 1.1 were modified using gamma radiation and an organic peroxide with the purpose of assessing the relative importance and form of evolution of the chain‐linking processes with these two methods. The copolymers used in this work were obtained by hydrogenation of polybutadienes, which were synthesized by anionic polymerization of butadiene. Part of these materials were irradiated by gamma rays in a 60Co radiation facility and the rest was modified with 2,5‐dimethyl‐2,5 di(terbutyl peroxy)‐hexane in the molten state. As expected, the critical radiation dose and the critical concentration of peroxide required for the onset of gelation decreases with average molecular weight of the original copolymer. Although, the chain‐linking reactions govern the modification process, there is a fraction of molecular chains that suffers scission. The measurable fraction of molecules having molecular weights lower than the original quasi‐monodisperse copolymers is, for both processes, about 5% of the total modified polymer. On the post‐gel region, the gel amount increases continuously with the radiation dose and the peroxide concentration added to the copolymers. For the radiation modified polymers, the calculation of the evolution of the molecular weights assuming ideal network forming conditions agreed very well with the experiments both, before and after the gel point. This is not accomplished when the modification process is done with the use of peroxides. Also, the results obtained from the peroxide modification processes at low relative concentrations with respect to the critical one for gelation show that the evolution of the structural modification evolves at a considerable lower rate than that observed in the radiation results.
Thermal Properties of Nanostructured Poly(acrylonitrile)–Silica Materials
Authors: Ruzimuradov Olim , Rajan Guru , Mark James 
Published: February 2007

AbstractThis report describes the thermal properties of nanostructured poly(acrylonitrile)–silica materials having potential as chromatography sorbents. Thermal analysis of nanostructured materials obtained by simultaneously polymerization of acrylonitrile and hydrolytical polycondensation of tetraethoxysilane are showed the presence of two exothermic peaks in the thermogramms of the poly(acrylonitrile)–silica materials.
Synthetic Paper from Plastic Waste: The Effect of CaCO3 on Physical, Surface Properties and Printability
Authors: Corrêa Ana Carolina , de Santi Cristiano Ribeiro , Manrich Sati 
Published: February 2007

AbstractThis article is a description of recent work in the development of composite sheet materials from blends of recycled high‐impact polystyrene (HIPS) and high‐density polyethylene (HDPE), with a view to using them as synthetic paper for the printing trade. Four monolayer films of differing composition were characterized in terms of their physical and surface properties. They were further evaluated compared with each other and with commercial synthetic and cellulose papers, to discover relationships between CaCO3 filler loadings, film structure and properties that could lead to improvements. In terms of their whiteness and water base inks printing properties, these sheets were generally inferior to the cellulose and synthetic papers. Notwithstanding this, in some tests they showed superior quality; thus, in offset printing, the high surface gloss, probably due to the HIPS content, made the colors brighter in some mono‐oriented film samples.
Crosslink Density of Peroxide Cured TPV
Authors: Vennemann Norbert , Bökamp Klaus , Bröker Dirk 
Published: February 2007

AbstractEPDM/PP model compounds were dynamically vulcanized by use of varying amounts of an organic peroxide and a trifunctional methacrylate to produce thermoplastic vulcanizates (TPV) materials with different properties. Tensile strength and ultimate elongation as well as compression set data of these materials are comparable to existing commercial TPV products. Although, crosslinking of the elastomer phase is the most important step during the production process, there is a lack of suitable test methods until now to determine the cross link density precisely. Therefore, a new test method, Temperature Scanning Stress Relaxation (TSSR) was examined to determine the crosslink density of the EPDM – phase. The results are in good agreement with results obtained from conventional swell measurements. The advantages of TSSR measurements over swell measurements are quite obvious. Whereas swelling measurements are very time consuming, TSSR tests are much easier and faster to perform. Additionally, information about the relaxation behavior and degradation of the PP ‐ phase was obtained from TSSR measurements.
Non‐heme iron through the three domains of life
Authors: Andreini Claudia , Banci Lucia , Bertini Ivano , Elmi Sara , Rosato Antonio 
Published: February 2007

AbstractMetalloproteins are proteins capable of binding one or more metal ions, which are often required for their biological function or for regulation of their activities or for structural purposes. In high‐throughput genome‐level protein investigation efforts, such as Structural Genomics, the systematic experimental characterization of metal‐binding properties (i.e. the investigation of the metalloproteome) is not always pursued, and remains far from trivial. In the present work we have applied a bioinformatic approach to investigate the occurrence of (putative) non‐heme iron‐binding proteins in 57 different organisms spanning the entire tree of life. It is found that the non‐heme iron‐proteome constitutes between 1% and 10% of the entire proteome of an organism. However, the iron‐proteome constitutes a higher fraction of the proteome in archaea (on average 7.1% ± 2.1%) than in bacteria (3.9% ± 1.6%) and in eukaryota (1.1% ± 0.4%). The analysis of the function of each putative iron‐protein identified suggests that extant organisms have inherited the large majority of their iron‐proteome from the last common ancestor. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Influence of cation mismatch on electrical, magnetic and magnetoresistance properties of Pr0.67A0.33MnO3manganites
Authors: Venkataiah G. , Venugopal Reddy P. 
Published: February 2007

AbstractWith a view to investigate the influence of A‐site cation mismatch on electrical, magnetic and magnetoresistance properties of Pr0.67A0.33MnO3, (A = Ca, Sr, Pb and Ba) manganites, a systematic investigation has been undertaken by preparing the materials using citrate gel route. The samples were characterized by X‐ray diffraction (XRD) and scanning electron microscopy. The XRD data were analyzed by Rietveld refinement method, while the crystallite sizes were estimated using the peak broadening technique. The unusual behavior of large magnetoresistance at low temperatures and at high magnetic fields has also been investigated. Finally, the high temperature electrical resistivity data were analyzed using variable range hopping and small polaron conduction mechanisms. A systematic investigation of the influence of average ionic radius of the A‐site (〈rA〉) and cation mismatch (σ2) on electrical and magnetic properties, viz., transition temperatures, density of states at Fermi level, polaron activation energies etc., has been undertaken. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrically driven quantum dot single photon source
Authors: Lochmann A. , Stock E. , Schulz O. , Hopfer F. , Bimberg D. , Haisler V. A. , Toropov A. I. , Bakarov A. K. , Scholz M. , Büttner S. , Benson O. 
Published: February 2007

AbstractWe report on a miniature solid state emitter structure, which allows electrical pumping of only one single InAs quantum dot (QD) grown in the Stranski‐Krastanow mode. The emitter demonstrates a strongly monochromatic polarized emission of a single QD exciton. Correlation measurements of the emitted photons show a clear antibunching behavior. The structure is thus attractive for practical implementation as effective single photon source for quantum cryptography. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical Landau state mapping with in‐plane electric fields
Authors: Karmakar Biswajit , Schardt Michael , Malzer Stefan , Arora Brij. M. , Döhler Gottfried H. 
Published: February 2007

AbstractWe report on a theoretical and experimental investigation of magneto‐absorption in quantum wells (QWs) in the presence of a uniform in‐plane electric field. From a simple theoretical model a linear real‐space shift of the electron Landau level wave functions relative to the hole counterparts is expected under increasing in‐plane electric field. As a result, quadratic Stark shifts, fading of the zero‐field allowed transitions, and increasing oscillator strength for the originally forbidden transitions are predicted. These predictions are confirmed by experiments on GaAs/AlGaAs‐QWs and found to be in reasonably good agreement with simulations based on a simple model. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Energy gap and bond lengths of AlxGayIn1–x –yN, AlxGayIn1–x –yP and AlxGayIn1–x –yAs quaternary alloys
Authors: Marques M. , Teles L. K. , Ferreira L. G. , Scolfaro L. M. R. , Furthmüller J. , Bechstedt F. 
Published: February 2007

AbstractWe use the Generalized Quasi‐Chemical Approach (GQCA) combined with ab initio ultrasoft pseudopotential calculations within density functional theory in order to obtain the structural and electronic properties of Alx Gay In1–x –y X (X = As, P or N) quaternary alloys in the zincblende structure. Results for the bond lengths show that their variations with composition are approximately linear and that they do not deviate much from the values of the corresponding binary compounds. For the variation of the band gaps, we obtain a bowing parameter b = 0.26 eV for the (Ga0.47In0.53As)z (Al0.48In0.52As)1–z quaternary alloy lattice matched to InP, in very good agreement with experimental data. In the case of AlGaInN, a bowing parameter of 0.22 eV is obtained for zincblende AlGaInN lattice matched to GaN. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Omni‐directional gap of 1‐D photonic crystals based on porous silicon with a Gaussian profile refractive index
Authors: Arriaga J. 
Published: February 2007

AbstractUsing the transfer matrix method we calculate the omni‐directional band gap of a 1‐D photonic crystal consisting of alternating layers of two dielectric materials A and B with refractive index nA and nB, respectively. The refractive index of layer A is constant and the refractive index of layer B varies according to the envelope of a Gaussian function. We find that under certain circumstances it is possible to obtain 100% reflectivity for both polarizations and any value of the incident angle of the electromagnetic waves. Although the structure considered does not posses a higher omni‐directional band gap than the periodic sequence of low and high constant refractive indexes, it can be used to produce a new type of omni‐directional mirrors without abrupt interfaces. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Symmetries and couplings in double quantum dot molecule
Authors: Bahamon D. A. , Camacho A. 
Published: February 2007

AbstractElectronic transport through a quantum dot molecule attached to leads has been very successfully studied finding very interesting effects like Fano and Kondo. In particular, the symmetry in quantum dot molecules going from the parallel to series coupling seems to play a very interesting role showing very different density of states spectra, these results have been obtained by fixing the interdot coupling equal to the coupling to the leads. In this work we go a step further by changing the value of the interdot coupling and the addition of on‐site Coulomb interaction with the help of Slave Boson Mean Field theory (SBMFT), Keldysh non equilibrium Green function technique and the equation of motion approach the density of states and the conductance of this system are calculated and analyzed in the Kondo regime. We also studied the asymmetric molecule set up of dots of different size in order to analyze the density of states and the Fano interference in an anticrossing region. Comparison of the results taking into account the Coulomb interaction is presented, which gives rise to the appearance of the Kondo effect in these systems. We also studied the interplay between the Kondo and Fano effects. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Excitonic effects in nonlinear optical rectification in small semi‐parabolic quantum dots
Authors: Baskoutas S. , Paspalakis E. , Terzis A. F. 
Published: February 2007

AbstractWe study the effects of excitons in nonlinear optical rectification in one‐dimensional semi‐parabolic quantum dots. We consider the case that the electron and the hole are confined in semi‐parabolic potential with the same oscillator frequency. We present approximate analytical results in the strong confinement regime and find a closed‐form relation between the nonlinear optical rectification coefficient of an exciton in the structure and the corresponding coefficient when only one electron exists in the structure. These results are also verified by numerical calculations performed with the potential morphing method. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Physical properties of quantum‐confined europium sulfide nanocrystals
Authors: Redígolo M. L. , Koktysh D. S. , Rosenthal S. J. , Dickerson J. H. 
Published: February 2007

AbstractWe report the synthesis and the characterization of quantum‐confined europium sulphide nanocrystals, which possess intriguing size‐dependent optical and magnetic properties. Transmission electron microscopy, X‐ray diffraction spectroscopy, and SQUID magnetization measurements provide evidence for the quantum‐confinement effects in this monochalcogenide nanomaterial. Photoluminescence measurements indicate a blue‐shifted spectrum for the nanocrystals compared with bulk europium sulphide. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ground state properties of zinc‐blende and wurtzite phases of MgS
Authors: Duman S. , Baǧcı S. , Tütüncü H. M. , Srivastava G. P. 
Published: February 2007

AbstractWe present an ab initio pseudopotential study, within the generalised gradient approximation, of the structural and electronic properties of zinc‐blende and wurtzite phases of MgS. The calculated structural parameters are in good agreement with previous experimental and theoretical results. Using the density‐functional perturbation theory, the phonon spectrum and density of states for the two phases have also been calculated. The calculated phonon modes for the zinc‐blende phase compare very well with a Raman scattering data at the zone‐centre. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ground state configurations of vertically coupled quantum rings
Authors: Castelano L. K. , Hai G.‐Q. , Partoens B. , Peeters F. M. 
Published: February 2007

AbstractThe ground states of two vertically coupled quantum rings are studied within the spin density functional theory for systems containing up to 13 electrons. Quantum tunneling effects on the electronic structure of the coupled rings are analyzed. New ground state configurations are found showing the formation of new diatomic artificial ring molecules. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)