bluuebunny/crossref_metadata_2025_split huggingface dataset:
Primary Productivity in a Polymictic Lake – Temporal Dynamics, Controlling Factors and Trophic State
Authors: Gervais Frank , Behrendt Horst 
Published: June 2004

AbstractThe seasonal and interannual dynamics of phytoplankton biomass, underwater light climate and primary productivity were studied in a phytoplankton‐dominated, polymictic lake (Müggelsee, Berlin, Germany) from 1994 to 1998. Turbidity was relatively high (k0 between 0.4 and 2.5 m–1) and the mixing depth often exceeded the euphotic depth. Therefore light was the most important factor limiting primary productivity. 82% of the observed variability in photosynthetic carbon uptake could be explained by a linear regression of carbon uptake against the product of chlorophyll a concentration and mean underwater irradiance. Annual productivity showed a rather large interannual variability (carbon uptake: 233–358 g C m–2 y–1; net oxygen productivity: 730–1150 g O2 m–2 y–1) that was clearly related to algal biomass and global radiation. Compared to the 1980s, the mean annual primary productivity has decreased by 33%.
A Comparative Analysis of Evenness Index Sensitivity
Authors: Beisel Jean‐Nicolas , Usseglio‐Polatera Philippe , Bachmann Vincent , Moreteau Jean‐Claude 
Published: June 2004

AbstractEvenness indices are numerous but the lack of knowledge of their properties is a limitation to their biological usefulness. 15 evenness indices, two of them being recently proposed, were studied in this work. We investigated the sensitivity of each index using (1) 189 macroinvertebrate communities sampled in the field, and (2) a set of communities modified in a controlled way.There is no single way to measure evenness. We demonstrated that a measure should be chosen considering (1) the kind of data analysed and, (2) the index properties wanted by users. Depending on the ecological data set the index should be more sensitive to variations in rare, median or abundant species. For most of macroinvertebrate community analyses, a convenient evenness index requirs to be symmetric, unsensitive to variation on rare taxa, with a large range of variation and can be compared with a diversity index. Depending on diversity measure used, five indices correspond to these criteria: EPielou, EHurlbert, E–ln(D), E1–D, EMI. Our results were summarized in a table which may help users to select a convenient evenness measure according to their specific data. Concerning index properties, three main features that an evenness index should meet are briefly discussed: dependence with richness, symmetry criteria and variation range. A revue of this controversial subject allowed a best understanding of values obtained with evenness measures depending on their own features.
Influence of Bed‐Sediment Features on the Interstitial Habitat Available for Macroinvertebrates in 15 French Streams
Authors: Gayraud Sebastien , Philippe Michel 
Published: June 2004

AbstractThe interstitial space of bed‐sediments is a major component of the stream system as it influences both physical and biological processes and patterns, such as exchanges between surface water and groundwater or the assemblage of invertebrates. To investigate the influence of grain‐size distribution and vertical bed‐packing on the interstitial habitat, we used 99 frozen cores collected from 15 French streams. On our data, overall invertebrate density, density of Chironomidae and taxon richness were more strongly related to effective porosity than to other physical variables describing bed‐sediments. We built two models to quantify the influence of grain‐size distribution and vertical bed‐packing on effective porosity. The effective porosity decreased with increasing grain‐size heterogeneity and was strongly related to grain‐size distribution. These relationships differed with vertical bed‐packing, but were consistent across three geologic types of sediments that varied in particle shape and particle texture. These general relationships suggest that effective porosity could be helpful to better understand the distribution patterns of invertebrates in bed‐sediments.
Patterns of gene expression in rat bone marrow stromal cells cultured on titanium alloy discs of different roughness
Authors: Leven Robert M. , Virdi Amarjit S. , Sumner Dale R. 
Published: June 2004

AbstractRat bone marrow stromal cells were cultured on either Ra (0.14 μm) or Ra (5.8 μm) Ti6Al4V discs for 24 or 48 h. Cells on the Ra (0.14 μm) surface showed typical fibroblastic morphology, whereas cells on the Ra (5.8 μm) surface were in clusters with a more epithelial appearance. RNA was extracted from the cells at both time points, and gene expression was analyzed by using a rat gene microarray. At 24 and 48 h, a similar number of genes were both up‐ and down‐regulated at least twofold on the Ra (5.8 μm) surface compared to the Ra (0.14 μm) surface. We analyzed the relative level of specific groups of genes related to bone and cartilage development, cell adhesion and extracellular matrix proteins, transcription factors, bone morphogenetic proteins, phospholipases, and protein kinases. Roughness did not appear to be a specific stimulator of osteogenesis because genes of both the bone and cartilage lineage were up‐regulated on the Ra (5.8 μm) surface. The most prominent change among transcription factors was up‐regulation of Hox 1.4 on the Ra (5.8 μm) surface. Up‐regulation of phospholipase A2 and SMAD 4 indicate these genes are also involved in the response of cells to an Ra (5.8 μm) surface. Our data show surface roughness alters the expression of a large number of genes in marrow stromal cells, which are related to multiple pathways of mesenchymal cell differentiation. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 70A: 391–401, 2004
Solvent effects on the microstructure and properties of 75/25 poly(D,L‐lactide‐co‐glycolide) tissue scaffolds
Authors: Sander Edward A. , Alb Alina M. , Nauman Eric A. , Reed Wayne F. , Dee Kay C 
Published: June 2004

AbstractPoly(lactide‐co‐glycolide) (PLGA) is used in many biomedical applications because it is biodegradable, biocompatible, and FDA approved. PLGA can also be processed into porous tissue scaffolds, often through the use of organic solvents. A static light scattering experiment showed that 75/25 PLGA is well solvated in acetone and methylene chloride, but forms aggregates in chloroform. This led to an investigation of whether the mechanical properties of the scaffolds were affected by solvent choice. Porous 75/25 PLGA scaffolds were created with the use of the solvent casting/particulate leaching technique with three different solvents: acetone, chloroform, and methylene chloride. Compression testing resulted in stiffness values of 21.7 ± 4.8 N/mm for acetone, 18.9 ± 4.2 N/mm for chloroform, and 30.2 ± 9.6 N/mm for methylene chloride. Permeability testing found values of 3.9 ± 1.9 × 10−12 m2 for acetone, 3.6 ± 1.3 × 10−12 m2 for chloroform, and 2.4 ± 1.0 × 10−12 m2 for methylene chloride. Additional work was conducted to uncouple polymer/solvent interactions from evaporation dynamics, both of which may affect the scaffold properties. The results suggest that solvent choice creates small but significant differences in scaffold properties, and that the rate of evaporation is more important in affecting scaffold microstructure than polymer/solvent interactions. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 70A: 506–513, 2004
Increased apoptosis of periprostatic adipose tissue in VDR null mice
Authors: Guzey Meral , Jukic Drazen , Arlotti Julie , Acquafondata Marie , Dhir Rajiv , Getzenberg Robert H. 
Published: June 2004

AbstractThe vitamin D receptor (VDR) is a member of the steroid/retinoid receptor superfamily of nuclear receptors that controls mineral ion homeostatis and has potential tumor‐suppressive functions for various cancer types, specifically prostate cancer. A VDR ablated transgenic animal model (VDDRII, vitamin D‐dependent rickets type II) has been developed and the animals typically have various diseases including, hypocalcemia, hyperparathyroidism, rickets, osteomalacia, and alopecia. This transgenic mouse system provides us with a model to decipher the influences of the VDR on prostatic growth and function. VDRs are abundant both in prostatic epithelial and stromal cells, and vitamin D signaling can be studied in this model. Although, there were no gross differences between the prostate tissue of the experimental and control groups, VDR null mice showed fat necrosis and individual cell apoptosis in the periprostatic adipose tissue. This indicates a possible role of VDR in the signaling pathways resulting the prostate. This may be particularly attractive for VDR targets for the inhibition of cancer progression using VD3 and its analogs as potential chemo‐preventive agents. © 2004 Wiley‐Liss, Inc.
Role of N‐methyl‐D‐aspartate receptors in gastric mucosal blood flow induced by histamine
Authors: Tsai Li Hsueh , Lee Yih‐Jing , Wu Jang‐Yen 
Published: June 2004

AbstractIonotropic N‐methyl‐D‐aspartate (NMDA) receptor agonists, L‐aspartic acid (L‐Asp) and NMDA, have been shown to inhibit histamine‐stimulated acid secretion, but their effect on gastric mucosal blood flow (GMBF) is largely unknown. The aim of this study was to investigate whether L‐Asp and NMDA inhibit histamine‐stimulated GMBF and to examine the expression patterns of NMDA receptor subunits NR1, NR2A, and NR2B in rat stomach. Laser Doppler flowmetry was used to measure gastric blood flow in anesthetized rats. The GMBF was assessed during an intravenous infusion of histamine in the presence of tripelennamine. The effects of L‐Asp and NMDA on histamine‐induced gastric blood flow were examined. In addition, the distribution patterns of NR1‐, NR2A‐, and NR2B‐contaning NMDA receptors in rat stomach were determined immunohistochemically by using specific antibodies against NR1, NR2A, and NR2B. Histamine‐induced enhancement of GMBF depended on acid secretion and the activation of H2‐receptors. Neither L‐Asp nor NMDA had an effect on the spontaneous GMBF. However, L‐Asp and NMDA reduced the histamine‐induced increase in GMBF. DL‐2‐amino‐5‐phosphonopentanoic acid (AP‐5), an NMDA receptor antagonist; and prazosin, an α1‐receptor antagonist; but not propanolol, a β2‐receptor antagonist; or yohimbine, a α2‐receptor antagonist; reversed the inhibitory effect of L‐Asp and NMDA on the histamine‐induced increase in GMBF. Therefore, L‐Asp and NMDA inhibit histamine‐induced GMBF via a mechanism involving the activation of NMDA receptors and α1‐ adrenoceptors. The fact that NMDA receptor subunits NR1, NR2A, and NR2B were found to be localized in the rat stomach as visualized immunohistochemically with specific antibodies against NR1, NR2A, and NR2B is consistent with this hypothesis. © 2004 Wiley‐Liss, Inc.
Antinociceptive effects of galanin in the rat tuberomammillary nucleus and the plasticity of galanin receptor 1 during hyperalgesia
Authors: Sun Yan‐Gang , Li Ji , Yang Bo‐Ning , Yu Long‐Chuan 
Published: June 2004

AbstractAlthough the tuberomammillary nucleus (TM) is well defined in terms of anatomy and neurochemistry, little is known about its function in nociceptive modulation. There was an abundance of galanin‐immunoreactive fibers in the TM, and galanin has been implicated in pain processing. The present study assessed the role of galanin in the modulation of nociception in the TM of rats. Intra‐TM injection of galanin dose‐dependently increased the hindpaw withdrawal latency of rats to a noxious thermal stimulus, indicating an antinociceptive role of galanin in the TM. The antinociceptive effect of galanin was blocked by a subsequent intra‐TM injection of galantide, a putative galanin receptor antagonist, suggesting that the antinociceptive effect of galanin is mediated by galanin receptors. Moreover, there was abundant galanin receptor 1 (GalR1) in the TM, and the number of GalR1‐positive neurons in the ipsilateral TM increased significantly after unilateral loose ligation of the sciatic nerve compared with the contralateral TM or the TM of intact rats. However, the number of GalR1‐positive neurons was not significantly altered by carrageenan‐induced inflammation, in either the ipsilateral or the contralateral TM. The results suggest that galanin and GalR1 in the TM may play important roles in pain regulation. © 2004 Wiley‐Liss, Inc.
On‐site Raman analysis of Iznik pottery glazes and pigments
Authors: Colomban Philippe , Milande Véronique , Le Bihan Lionel 
Published: June 2004

AbstractOn‐site Raman analyses were performed at the Musée National de Céramique, Sèvres, France, on rare Iznik (former Nicaea) pottery produced from ∼1480 to ∼1620. A comparison was made with a series of shards. The town of production of these potteries was highly disputed in the 1980s and many questions still remain. The potential of glaze on‐site analyses as a classification/dating tool was evaluated. The structure of the silicate glaze does not change with the sample (index of polymerization ∼0.5–0.8, indicating a lead silicate composition); characteristic SiO stretching mode doublet at ∼985 and 1030–1050 cm−1. By contrast, the corresponding signature of most of the ‘Kütahya’ wares peaks at ∼1070–1090 cm−1. The lowest index is measured for a brilliant overglazed red bole, according to a lower temperature of (post)firing. The different crystalline phases identified in the glaze are α‐quartz, haematite, spinel, cassiterite, uvarovite garnet and zircon. White colour arises from α‐quartz slip in most samples studied. Cassiterite (SnO2) opacifier is only present in some early blue‐and‐white ceramics (Master of the Knots and Baba Nakkas style, ∼1510–1530) and we do not have other evidence of its intentional use as an opacifier. Intentional addition of tin oxide is likely for colour lightening in some red, blue and in clear green boles. At least two types of red glazes and two types of Cr‐containing green pigments are evidenced. Copyright © 2004 John Wiley & Sons, Ltd.
Raman scattering probe of anharmonic effects in NiSi
Authors: Donthu S. K. , Tripathy S. , Chi D. Z. , Chua S. J. 
Published: June 2004

AbstractWe report a systematic temperature‐dependent Raman scattering study of NiSi thin films. In agreement with the basic anharmonic theory, the strong Raman peak from NiSi at about 214 cm−1 shows phonon softening and broadening with an increase in the sample temperature. Comparative study of the temperature dependence of this first‐order Raman peak from NiSi powder and the film show that NiSi layers of thickness 15–90 nm are under tensile thermal stress. The results also show that the total phonon shift observed in the temperature range 80–500 K is independent of the silicide film thickness. We have also shown that Raman spectroscopy is a faster and more sensitive technique than x‐ray diffraction for phase identification in NiSi nanolayers, hence Raman scattering can be used as a valuable tool for in situ growth and process monitoring of nickel silicides. Copyright © 2004 John Wiley & Sons, Ltd.
Use of a fibre‐optic probe for the identification of asbestos fibres in bulk materials by Raman spectroscopy
Authors: Bard Delphine , Tylee Barry , Williams Ken , Yarwood Jack 
Published: June 2004

AbstractWithin the UK, a large number of surveys are being carried out for the identification of asbestos in building materials. Pre‐demolition or major refurbishment and building sampling surveys require that representative samples be analysed for asbestos. The primary technique for the analysis of asbestos fibres in bulk materials is polarized light microscopy (PLM). Since this method is based on visual estimation, it depends on the competence and experience of the analyst. Furthermore, PLM, in common with the other analytical methods used for the identification of asbestos in bulk materials, is a laboratory‐based technique requiring samples to be collected and then sent to a laboratory for analysis. Raman spectroscopy is a powerful tool for mineral characterization and provides a molecular fingerprint for material. In recent years, new developments in optics and electronics have permitted the development of compact Raman spectrometers allowing in situ measurements. We report the performance of a robust, laboratory‐based fibre‐optic probe for the identification of asbestos in bulk materials by Raman spectroscopy. Thirty‐eight samples were analysed, and the results showed that 95% of the samples were successfully identified as either asbestos free or containing one or more asbestos components. A success rate of 100% was found for asbestos insulating board and asbestos cement materials. The results indicated that a Raman probe device for detecting asbestos does have potential, but a number of issues need to be addressed before an on‐site system can be developed. Copyright © 2004 John Wiley & Sons, Ltd.
Raman spectroscopic study of the epicuticular wax layer of mature mango (Mangifera indica) fruit
Authors: Prinsloo Linda C , du Plooy Wilma , van der Merwe Chris 
Published: June 2004

AbstractLittle is known about the chemical composition of the natural wax layer covering mango (Mangifera indica) fruit. We report here on the role of Raman spectroscopy in a study that was undertaken to characterize the epicuticular wax of mature mango fruit. Scanning electron microscope measurements showed two morphologically distinct parts in the wax layer and Raman microscopy determined that they are chemically distinct. Crystalline aliphatic compounds protrude from an amorphous layer in which long‐chain aliphatic, aromatic and unsaturated compounds are present. Raman spectra recorded on the perimeter of lenticels indicate an absence of the crystalline aliphatic compounds in this region and this information could assist in the solution of the problem faced by the mango industry of the discoloration around lenticels, which makes the fruit unacceptable as an export product. The results are supported by Fourier transform IR spectroscopy and both techniques are now employed as probes in a long‐term project to study dynamic changes of the wax during fruit development and eventual processing, which includes the monitoring of possible changes in carotenoid content and the role of dust particles embedded in the wax. Copyright © 2004 John Wiley & Sons, Ltd.
Preparation of SERS‐active gold film electrodes via electrocrystallization: their characterization and application with NIR excitation
Authors: Sauer G. , Brehm G. , Schneider S. 
Published: June 2004

AbstractThe electrodeposition of a sufficiently large amount of gold on vapor‐deposited film electrodes at high overpotentials leads to excellent substrates for surface‐enhanced Raman scattering (SERS) spectroscopy. The SERS enhancement factor is estimated to be >107 with near‐infrared excitation, a value which is superior to that for gold surfaces roughened by conventional oxidation–reduction cycles. Its wavelength dependence was studied over a wide range of excitation wavelengths and compared with that of silver electrodes prepared in an analogous manner. Furthermore, the broad applicability of the SERS‐active gold film electrodes was demonstrated using numerous environmentally relevant s‐triazine derivatives containing amino and/or thioether groups as probe molecules. Finally, it is shown that the high stability of the roughened gold surfaces allows even strongly adsorbed molecules to be removed by plasma cleaning without distinctly altering the SERS enhancement factor. First results allow the conclusion that this type of SERS‐active surfaces is well suited for their repeated use. Copyright © 2004 John Wiley & Sons, Ltd.
Raman investigation of the structural changes in anatase LixTiO2 upon electrochemical lithium insertion
Authors: Baddour‐Hadjean Rita , Bach Stéphane , Smirnov Mikhail , Pereira‐Ramos Jean‐Pierre 
Published: June 2004

AbstractMicro‐Raman spectrometry and x‐ray diffraction (XRD) experiments were performed on the anatase LixTiO2 system (0 ≤ x ≤ 0.6) produced from the electrochemical discharge of a TiO2 composite cathode in propylene carbonate LiClO4 solution at room temperature. Raman spectrum modifications indicate local structural and chemical changes as lithium enters the anatase host lattice. The existence of a tetragonal to orthorhombic phase transition is clearly demonstrated by the Raman and XRD measurements. Moreover, lithium extraction is only partially quantitative for Li uptake ≤0.5, as shown both from structural and electrochemical data in the 3–1.5 V potential range. For the first time, the Raman fingerprint of the lithium titanate (LT) Li0.5TiO2 orthorhombic phase is clearly evidenced. A theoretical analysis of the lattice dynamics suggested a complete interpretation of the experimental Raman spectra in the LixTiO2 system, which provided valuable information on the Li atom positions and coordination in LT. Taking into account the possibility of rather short LiO distances, the complex band structure in the high‐wavenumber region is assigned to the LiO vibrations. Furthermore, spectra simulation offers an explanation for the new shape of the TiO2 lattice modes observed in the low‐wavenumber region. Copyright © 2004 John Wiley & Sons, Ltd.
Conformational analysis of tetrapeptides by exploiting the excitonic coupling between amide I modes
Authors: Huang Qing , Schweitzer‐Stenner Reinhard 
Published: June 2004

AbstractThe amide I band of the IR and to a lesser extent also of the corresponding visible Raman spectra of peptides and proteins are frequently used to determine their secondary structure composition. Thus far, however, this analytical approach is generally a low‐resolution technique, particularly because it mostly discriminates only between α‐helical, β‐sheet (parallel and antiparallel) and so‐called random coil conformations. This study shows that for tetrapeptides the combined use of the IR and Raman amide I band profiles allows one to discriminate currently known secondary structure motifs. To exploit the spectral information to its fullest extent, we developed an algorithm which calculates the amide I intensity profiles of IR, isotropic and anisotropic Raman scattering and also the depolarization ratios of the Raman bands as a function of the dihedral angles of the two central amino acid resides. The approach is based on a quantum mechanical treatment of the vibrational coupling between the amide I modes of the three peptide groups in the framework of a coupled oscillator model. We calculated the band profiles of a representative set of secondary structures, i.e. a right‐handed α‐helix, a 310‐helix, β‐sheets and a polyproline II (PPII)‐type 31‐helix and β‐turns. Our results unambiguously show that all these secondary structure motifs can be identified by comparing experimentally observed IR and Raman amide I bands with their respective calculated intensity distributions. Copyright © 2004 John Wiley & Sons, Ltd.