bluuebunny/crossref_metadata_2025_split huggingface dataset:
Localization of estrogen receptor‐α and ‐βmRNA in brain areas controlling sexual behavior in Japanese quail
Authors: Halldin Krister , Axelsson Jeanette , Holmgren Claes , Brunström Björn 
Published: October 2005

AbstractTwo estrogen receptors (ERs), denoted ERα and ERβ, have been identified in humans and various animal species, including the Japanese quail. Estrogens play a key role in sexual differentiation and in activation of sexual behavior in Japanese quail. The distribution of ERα in the brain of male and female adult quail has previously been studied using immunohistochemistry, whereas in situ hybridization has been employed to study the distribution of ERβ mRNA in males only. In this article, we used in situ hybridization to study the distribution of mRNAs for both ERα and ERβ in brain areas controlling sexual behavior of Japanese quail. Our results show that both ERα mRNA and ERβ mRNA are localized in areas important for sexual behavior, such as the preoptic area and associated limbic areas, in both males and females. Moreover, we found differences in distribution of mRNA for the two receptors in these areas. The results of this article support previously reported data and provide novel data on localization of ER mRNAs in adult quail brain of both sexes. © 2005 Wiley Periodicals, Inc. J Neurobiol, 2005
HGF induction of postsynaptic specializations at the neuromuscular junction
Authors: Madhavan Raghavan , Peng H. Benjamin 
Published: October 2005

AbstractA critical event in the formation of vertebrate neuromuscular junctions (NMJs) is the postsynaptic clustering of acetylcholine receptors (AChRs) in muscle. AChR clustering is triggered by the activation of MuSK, a muscle‐specific tyrosine kinase that is part of the functional receptor for agrin, a nerve‐derived heparan sulfate proteoglycan (HSPG). At the NMJ, heparan sulfate (HS)‐binding growth factors and their receptors are also localized but their involvement in postsynaptic signaling is poorly understood. In this study we found that hepatocyte growth factor (HGF), an HS‐binding growth factor, surrounded muscle fibers and was localized at NMJs in rat muscle sections. In cultured Xenopus muscle cells, HGF was enriched at spontaneously occurring AChR clusters (hot spots), where HSPGs were also concentrated, and, following stimulation of muscle cells by agrin or cocultured neurons, HGF associated with newly formed AChR clusters. HGF presented locally to cultured muscle cells by latex beads induced new AChR clusters and dispersed AChR hot spots, and HGF beads also clustered phosphotyrosine, activated c‐Met, and proteins of dystrophin complex; clustering of AChRs and associated proteins by HGF beads required actin polymerization. Lastly, although bath‐applied HGF alone did not induce new AChR clusters, addition of HGF potentiated agrin‐dependent AChR clustering in muscle. Our findings suggest that HGF promotes AChR clustering and synaptogenic signaling in muscle during NMJ development. © 2005 Wiley Periodicals, Inc. J Neurobiol, 2005
HPLC comparison of supercritical fluid extraction and solvent extraction of coumarins from the peel of Citrus maxima fruit
Authors: Teng Wen‐Yuh , Chen Chien‐Chih , Chung Ren‐Shih 
Published: October 2005

AbstractThe efficiency of carbon dioxide supercritical fluid extraction (SFE) of the biologically active compounds imperatorin, meranzin and meranzin hydrate from the fruit peel of Citrus maxima Merr. has been compared with that of solvent extraction with acetone. Under the best SFE conditions tested for the three coumarins, which involved extraction at 50°C and 27.6 MPa, the extractive efficiencies were 84, 76 and 18% for imperatorin, meranzin and meranzin hydrate, respectively. The presence of modifiers significantly affected the extraction efficiency: the highest extraction efficiency of the three coumarins was obtained with ethanol as modifier. Copyright © 2005 John Wiley & Sons, Ltd.
Study of the products of melamine (C3N6H6) treated at high pressure and high temperature
Authors: Yao L. D. , Li F. Y. , Li J. X. , Jin C. Q. , Yu R. C. 
Published: October 2005

AbstractA black‐brown powder was synthesized from melamine (C3N6H6) at 850 °C and 4.5 GPa. There are two possibilities for the sample phase components based on the analyses of C/N/H elements and X‐ray diffraction patterns. One is that the powder is composed of 2H‐type g‐C3N4 and some intermediate phases, while the other is that it consists of some undecomposed raw material, graphite and intermediate phases. The existence of the intermediate phase with long periodicity along one direction is confirmed through transmission electron microscopy observations. Scanning electron microscopy images show many block regions, in which a few holes exist. The atomic fraction of carbon and nitrogen was checked with energy dispersive X‐ray analysis, and the chemical bond states were investigated by Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy. Based on the general analysis of the experimental results, the second possibility is favoured. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Behaviour of diffusion thermopower in Bloch–Grüneisen regime in AlGaAs/GaAs and AlGaN/GaN heterostructures
Authors: Sankeshwar N. S. , Kamatagi M. D. , Mulimani B. G. 
Published: October 2005

AbstractThe behaviour of diffusion thermopower Sd, in AlGaAs/GaAs and AlGaN/GaN heterojunctions, in the Bloch‐Grüneisen (BG) regime is examined taking into account the temperature dependent effects arising from screening of the electron‐phonon interaction and thermal averaging over the carrier distribution. Sd is found to follow a non‐linear temperature dependence before becoming linear as it approaches T = 0 K. This is in contrast to the usual linear dependence used, in literature, in the analysis of thermopower S. The overall behaviour of S is influenced by the phonon‐drag contribution, Sg. The calculations of both Sd and Sg, presented, demonstrate the importance of the proper inclusion of the temperature dependent effects, as in the mobility studies, in the BG regime. An analysis of the thermopower data in ultra‐pure samples at very‐low temperatures will enable better understanding of electron–phonon interaction. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Exciton photoconductivity in Ge‐doped GaSe crystals
Authors: Mamedov G. M. , Karabulut M. , Kodolbaş A. O. , Öktü Ö. 
Published: October 2005

AbstractSpectral photoconductivity in Ge‐doped GaSe crystals was investigated as a function of temperature. It is found that when the crystal is doped with small concentrations of Ge atoms (0.01 at%), the photoconductivity is carried out by the ionization of the excitons. In these crystals, exciton photoconductivity is found to have an Urbach tail similar to the tail observed in exciton absorption. Investigation of the temperature dependence of the peak positions (Eexc(T)) and line widths (Γexc(T)) of the photoconductivity spectra indicates that the exciton ionization is due to the exciton–phonon and exciton–impurity interactions. From the analyses of the Eexc(T) and Γexc(T) data, it is found that at low temperatures (T < 50 K) the exciton–phonon interaction takes place via rigid‐layer phonon modes while in the 50–300 K temperature range it takes place via phonons with hνp ≈ 18 meV. In the 300–450 K range the energy of the phonons involved in the exciton–phonon interaction is hνp ≈ 36 meV. The anisotropy observed in the exciton photoconductivity taken parallel and perpendicular to the layers of doped GaSe crystals diminishes at T = 300 K and the peak positions of the photoconductivity in both directions coincide with the peak position of the free exciton peak (n = 1) in the absorption spectrum. Another important result found is that in these layered GaSe crystals the exciton states continue to exist at high temperatures, up to 450 K. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comment on “Dipolar interaction energy for a system of magnetic nanoparticles” [phys. stat. sol. (b) 241, No. 13, 3022–3028 (2004)]
Authors: Tang Ke , Zhang Huaiwu , Zhong Zhiyong 
Published: October 2005

AbstractIt is pointed out that there exist singularities in the equations describing the dipolar interaction energy derived by S. Lamba. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)See original phys. stat. sol. (b) Vol. 241, No. 13, 3022–3028 (2004)
Reply to “Comment on ‘Dipolar interaction energy for a system of magnetic nanoparticles’” [phys. stat. sol. (b), DOI 10.1002/pssb.200540104]
Authors: Lamba Subhalakshmi 
Published: October 2005

AbstractIn this reply we clarify some points regarding the applicability of the expressions for the dipolar interaction energy between magnetic nanoparticles as calculated by an extension of the Lekner summation methods. The calculation is shown to be valid for any finite separation between the particles. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)See original
Calculation of the changes in the absorption and refractive index for intersubband optical transitions in a quantum box
Authors: Karabulut İ. , Ünlü S. , Şafak H. 
Published: October 2005

AbstractAnalytic forms of the changes of the absorption and refractive index associated with intersubband optical transitions in a quantum box are obtained by using the compact density matrix approach. Numerical results are presented for a typical AlGaAs/GaAs quantum box system. The linear, third‐order nonlinear, and total refractive‐index and absorption changes are examined as a function of the incident optical intensity. The results obtained show that the incident optical intensity has a great effect on the total absorption and refractive‐index changes. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
General approach for the construction of hybrid orbitals
Authors: Álvarez‐Bajo O. , Lemus R. 
Published: October 2005

AbstractA general approach to construct hybrid orbitals based on the projection of both the subspace of atomic orbitals and the subspace of hybrid orbitals is presented. It is shown that the projection must be associated with a chain of groups to ensure the independence of the method with respect to the selected coordinate system. The eigenfunction method to obtain symmetry projected functions turns out to be the natural projection technique to establish the present approach. The proposed method allows construction of hybrid orbitals in a systematic and general way, even in the hypothetical case where irreducible representations are contained more than once in the reduction of the space of hybrid orbitals. To illustrate our approach, a hybridization d2sp3 for octahedral molecules is discussed. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Reaction of CH3O2 and HO2: Ab initio characterization of dimer structure and vibrational mode analysis for reaction mechanisms
Authors: Zhou Xin‐Ming , Zhou Zheng‐Yu , Wu Qun‐Yan , Jalbout Abraham F. , Zhang Nan 
Published: October 2005

AbstractAll species involved in the multi‐channel reaction of CH3O2 with HO2 have been investigated using density functional theory (DFT). The molecular geometries for various species are optimized employing the B3LYP method implementing the 6‐311++G** basis set. The relative energies of all species are calculated at the same level theory. The results show that there are two kinds of channels: singlet and triplet. The singlet channel involves four intermediates and six transition states. The triplet channel includes two intermediates and two transition states. There are four kinds of reaction products: CH3OOH + 1O2, CH3OH + O3, CH4 + 2O2, and CH3OOH + 3O2. The vibrational mode analysis is used to elucidate the relationships of the intermediates, the transition states, and the products. The extensive investigation shows that the reaction mechanism is reliable. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Bare Coulomb field and atomic reciprocal form factor
Authors: Angulo J. C. , Romera E. 
Published: October 2005

AbstractThe reciprocal form factor of N‐electron closed shells systems in a bare Coulomb field is shown to be a spherically symmetric, positive, and decreasing function of the radial distance. Nonmonotonicities of the reciprocal form factor appear when studying bare Coulomb field open‐shell systems. Analysis of the weight of the interelectronic repulsion term is carried out for some isoelectronic series as well as neutral atoms with N = 1–103. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Ladder operators for the Kratzer oscillator and the Morse potential
Authors: Singh C. Amuba , Devi O. Babynanda 
Published: October 2005

AbstractTaking a close look at the Infeld–Hull ladder operators for the Kratzer oscillator system, V(x) = [x2 + β(β − 1)x−2]/2, we deduce and explicitly construct energy‐raising and ‐lowering operators for the generalized Morse potential system V(z) = (Ae−4αz − Be−2αz)/2, through a canonical transformation that exists between the two systems. For the Morse potential system, we obtain a system of raising and lowering operators P±(n) (n = 0, 1, 2, 3, … , nmax) with the specific property that P±(n)Φn = c±(n)Φn±1, where Φn denotes the nth energy eigenfunction. While P−(0) annihilates the ground‐state Φ0, the operator P+(nmax), instead of annihilating the highest bound‐state Φ, actually knocks it out of the L2 space spanned by the discrete bound states and becomes inadmissible. Yet, raising and lowering operators $\hat{P}$± with proper end‐of‐spectrum behavior (i.e., $\hat{P}$−|0〉 = 0 and $\hat{P}$+|nmax〉 = 0) can be constructed in a straightforward way in the energy representation. We show that the operators $\hat{P}$+, $\hat{P}$−, and $\hat{P}$0 (where $\hat{P}$0 ≡ (1/2)[$\hat{P}$+, $\hat{P}$−]) form a su(2) algebra only if we restrict them to the (N − 1)‐dimensional subspace spanned by the lowest (N − 1) basis vectors, but not in the full (N + 1)‐dimensional space spanned by the discrete bound states [N ≡ nmax ≡ integral part of (1/2)(B/(2α$\sqrt{A}$) − 1)]. Realization of this su(2) algebra in the position representation (when restricted to the (N − 1)‐dimensional subspace) is also given. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Feynman propagator and Slater sum for a model Hamiltonian motivated by H in an intense magnetic field
Authors: Amovilli Claudio , March Norman H. 
Published: October 2005

AbstractIn an early study of the hydrogen molecule ion in a magnetic field of strength B directed along the internuclear axis, we wrote the ground‐state electronic energy E(R, B), with R the internuclear separation, in terms of the electron and current densities ρ(r) and j(r), respectively. Very recent work by Benguria et al. has established a one‐dimensional model Hamiltonian that is asymptotically valid in the limit as the magnetic field strength B tends to infinity. We study a model motivated by this Hamiltonian and derive exact analytical results for the Slater sum and for the Feynman propagator. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Role of angular electron pair correlation in stabilizing C
Authors: Difley Seth , Simons Jack 
Published: October 2005

AbstractA pseudo‐potential that was successfully employed in an earlier study by the Compton group is used to describe the binding of a single electron to a C60 molecule to form C. Then, the interaction of a second electron with the C anion is treated in two manners. First, as performed in the earlier Compton study, a mean‐field (i.e., Hartree–Fock) approach is used to estimate the C‐to‐C energy difference for the singlet state of the dianion and, much as in the earlier study, this dianion is predicted to be unstable by ∼0.4 eV. Second, for this same singlet state, a configuration interaction wave function is employed that allows for the angular correlation of the two excess electrons, allowing them to avoid one another by moving on opposite sides of the C60 skeleton. The energy of the dianion is lowered by 0.3 eV when angular correlation is included, suggesting that the singlet dianion is unstable with respect to electron loss by only ∼0.1 eV. A Coulomb barrier (>1 eV high) and angular momentum barriers then combine to trap electrons of singlet C from detaching, thus producing the very long observed lifetimes. In addition, the energy of the lowest triplet state of C is also discussed. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Power sources for portable electronics and hybrid cars: lithium batteries and fuel cells
Authors: Scrosati Bruno 
Published: October 2005

AbstractThe activities in progress in our laboratory for the development of batteries and fuel cells for portable electronics and hybrid car applications are reviewed and discussed. In the case of lithium batteries, the research has been mainly focused on the characterization of new electrode and electrolyte materials. Results related to disordered carbon anodes and improved, solvent‐free, as well as gel‐type, polymer electrolytes are particularly stressed. It is shown that the use of proper gel electrolytes, in combination with suitable electrode couples, allows the development of new types of safe, reliable, and low‐cost lithium ion batteries which appear to be very promising power sources for hybrid vehicles. Some of the technologies proven to be successful in the lithium battery area are readapted for use in fuel cells. In particular, this approach has been followed for the preparation of low‐cost and stable protonic membranes to be proposed as an alternative to the expensive, perfluorosulfonic membranes presently used in polymer electrolyte membrane fuel cells (PEMFCs). © 2005 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 5: 286–297; 2005: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20054
Evolutionary relationship and application of a superfamily of cyclic amidohydrolase enzymes
Authors: Nam Sung‐Hun , Park Hee‐Sung , Kim Hak‐Sung 
Published: October 2005

AbstractCyclic amidohydrolases belong to a superfamily of enzymes that catalyze the hydrolysis of cyclic CN bonds. They are commonly found in nucleotide metabolism of purine and pyrimidine. These enzymes share similar catalytic mechanisms and show considerable structural homologies, suggesting that they might have evolved from a common ancestral protein. Homology searches based on common mechanistic properties and three‐dimensional protein structures provide clues to the evolutionary relationships of these enzymes. Among the superfamily of enzymes, hydantoinase has been highlighted by its potential for biotechnological applications in the production of unnatural amino acids. The enzymatic process for the production of optically pure amino acids consists of three enzyme steps: hydantoin racemase, hydantoinase, and N‐carbamoylase. For efficient industrial application, some critical catalytic properties such as thermostability, catalytic activity, enantioselectivity, and substrate specificity require further improvement. To this end, isolation of new enzymes with desirable properties from natural sources and the optimization of enzymatic processes were attempted. A combination of directed evolution techniques and rational design approaches has made brilliant progress in the redesign of industrially important catalytic enzymes; this approach is likely to be widely applied to the creation of designer enzymes with desirable catalytic properties. © 2005 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 5: 298–307; 2005: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20057
Growth strategy of the stoloniferous rattanCalamus javensisin Mt. Halimun, Java
Authors: Watanabe Natsuki M. , Miyamoto Junko , Suzuki Eizi 
Published: October 2005

AbstractCalamus javensisis a widespread understorey rattan in Southeast Asia and is one of the dominant rattan species in Mt. Halimun National Park, West Java. This species can establish clumps either sexually with seeds or clonality with stolons. To analyze the role of sexual reproduction and clonality for clump establishment inC. javensis, we studied the vegetative and genetic structures of the population. Totals of 2,777 ramets comprising 1,321 clumps were found in three 0.16 ha plots. The number of ramets per clump showed reverse J‐shaped distribution with a maximum of 15. Clustering and stoloniferous ramets accounted for 62 and 20% of all ramets, respectively. This indicates thatC. javensisis actively engaged in clustering clonal growth. The longest stem was 14 m although 75% of all stems were shorter than 1 m long. The stolon ranged from 6 to 538 cm in length, which decreased the local density of ramets. Using randomly amplified polymorphic DNA (RAPD) analysis, we obtained 56 polymorphic bands for 118 clumps sampled from one of the plots. All samples showed different RAPD banding patterns, except one pair at a distance of 225 cm from each other. The genetic similarity among samples closer than 10 m was significantly higher than the expected value from a purely random distribution. These results suggest that most separate clumps are established by recruitment from seeds, and most seeds dispersed near mother plants. Hence, inC. javensis, clonality is more a growth strategy to increase the size of the genet than a dispersion‐propagation strategy to expand the habitat.
Plant species composition in relation to green cover configuration and function of urban parks in Beijing, China
Authors: Li Weifeng , Ouyang Zhiyun , Meng Xuesong , Wang Xiaoke 
Published: October 2005

AbstractParks, as one specific type of urban open space, play important roles in the conservation of urban biodiversity and provision of recreational services for local residents. As there is a lack of specific insight into park plant species composition in relation to park features, 24 sample parks within the inner city of Beijing, the capital of China, were studied by stratified random plot sampling of their tree, shrub, and herbaceous communities, respectively, in order to investigate how human activities have influenced park green cover configuration and floristic characteristics. The quantitative correlation of species richness and the park green cover indices (patch size, shape, etc.) were studied. The importance value index for plant species (trees, shrubs, and herbaceous species) of each park was calculated. The two‐way indicator species analysis approach (TWINSPAN) was applied to classify the 24 parks into different groups based on their species assemblages. Two‐hundred and eighty‐eight species were recorded within the 24 study parks, belonging to 184 genera and 72 families dominated by Gramineae, Compositae, and Leguminosae. Among all the recorded species, 41% are exotic. The species occurrence, abundance and diversity vary significantly among different parks. Besides the positive correlation (R=0.505, P<0.05) between herbaceous species abundance and the park green cover size, no other significant relations were found between the species abundance and other indices of park green cover configuration. Remarkably, the TWINSPAN classification resulted in a good discrimination between park functional types and the variation in their species assemblage. For the parks of similar age (development history) or landscape design, their species assemblages show more similarity. The methodology adopted and results can be employed to improve baseline information on urban plant ecology and support the setting of priorities for future park management and vegetation protection.