bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of the supraglacial snowpack in mediating meltwater delivery to the glacier system as inferred from dye tracer investigations
Authors: Campbell Fay M. A. , Nienow Peter W. , Purves Ross S. 
Published: February 2006

AbstractThe supraglacial snowpack plays an important role in mediating the delivery of meltwater produced at the snowpack surface to the rest of the glacier system, with potential implications for both proglacial hydrograph form and the timing and magnitude of glacier movement induced by changes in subglacial water pressure. However, there remain few field observations of the hydrological behaviour of supraglacial snowpacks and its seasonal evolution during the melt season. Data collected during the 2004 melt season at Haut Glacier d'Arolla, Valais, Switzerland, uses both qualitative and quantitative dye tracing techniques to enhance our understanding of supraglacial snowpack hydrology. Observations of the movement of dye‐stained water show the complexity of flow patterns and the influence of ice layers and preferential flow zones in controlling percolation through the snowpack, and fluorometric techniques yield average flow rates for percolation through the snowpack of between 0·13 and 0·49 m h−1. The changing form of dye‐return curves and increasing percolation rates reflect an increase over the course of the melt season in the efficiency with which the snowpack transmits meltwater. Snowpack permeability was found to be significantly lower (1·67 × 10−10 m2 on average) than that assumed in previous modelling studies of glacial hydrology, showing the need for improved information about snowpack hydrology if its importance in controlling runoff is to be fully appreciated. Copyright © 2006 John Wiley & Sons, Ltd.
SNOTEL representativeness in the Rio Grande headwaters on the basis of physiographics and remotely sensed snow cover persistence
Authors: Molotch Noah P. , Bales Roger C. 
Published: February 2006

AbstractIn this study we identify the physiographic and snowpack conditions currently represented by snowpack telemetry (SNOTEL) stations in the Rio Grande headwaters. Based on 8 years of advanced very high‐resolution radiometer data (1995–2002) a snow cover persistence index was derived. Snow cover persistence values at the seven SNOTEL sites ranged from 3·9 to 4·75, with an average 14% greater than the mean persistence of the watershed. Using elevation, western barrier distance, and vegetation density, a 32‐node binary classification tree model explained 75% of the variability in average snow cover persistence. Terrain classes encompassing the Lily Pond, Middle Creek, and Slumgullion SNOTEL sites represented 4·1%, 6·4%, and 4·0% of the watershed area respectively. SNOTEL stations do not exist in the spatially extensive (e.g. 11% of the watershed) terrain classes located in the upper elevations above the timberline. The results and techniques presented here will be useful for spatially distributed hydrologic analyses, in that we have identified the physiographic conditions currently represented by SNOTEL stations (i.e. the snowpack regimes at which snow water equivalent estimation uncertainty can be determined). Further, we outlined a statistically unbiased approach for designing future observation networks tailored for spatially distributed applications. Copyright © 2006 John Wiley & Sons, Ltd.
Molecular genetic evidence that endometriosis is a precursor of ovarian cancer
Authors: Prowse Amanda H. , Manek Sanjiv , Varma Rajesh , Liu Jinsong , Godwin Andrew K. , Maher Eamonn R. , Tomlinson Ian P.M. , Kennedy Stephen H. 
Published: February 2006

AbstractHistopathology and epidemiology studies have consistently demonstrated a strong link between endometriosis and endometriosis‐associated ovarian cancers (EAOCs)—in particular, the endometrioid and clear cell subtypes. However, it is still unclear whether endometriosis is a precursor to EAOCs, or whether there is an indirect link because similar factors predispose to both diseases. In order to search for evidence of clonal progression, we analyzed 10 EAOCs (endometrioid = 4; clear cell = 6) with coexisting endometriosis for common molecular genetic alterations in both the carcinoma and corresponding endometriosis. We used 82 microsatellite markers spanning the genome to examine loss of heterozygosity (LOH) in the coexisting carcinoma and endometriosis samples. A total of 63 LOH events were detected in the carcinoma samples; twenty two of these were also detected in the corresponding endometriosis samples. In each case, the same allele was lost in the endometriosis and cancer samples. Interestingly, no marker showed LOH in the endometriosis alone. These data provide evidence that endometriosis is a precursor to EAOCs. © 2006 Wiley‐Liss, Inc.
Comparative study into the robustness of compartmental modeling and model‐free analysis in DCE‐MRI studies
Authors: Roberts Caleb , Issa Basma , Stone Andrew , Jackson Alan , Waterton John C. , Parker Geoffrey J.M. 
Published: February 2006

AbstractPurposeTo evaluate and compare the reproducibility of the preferred phenomenological parameter IAUC60 (initial area under the time‐concentration curve [IAUC] defined over the first 60 seconds postenhancement) with the preferred modeling parameter (Ktrans), as derived using two simple models, in abdominal and cerebral data collected in typical Phase I clinical trial conditions.Materials and MethodsDynamic contrast enhanced MRI (DCE‐MRI) time series were acquired at two imaging centers from a group of patients with abdominal tumors and a group with gliomas. At both imaging centers, precontrast T1 was calculated using a variable flip angle three‐dimensional spoiled gradient echo acquisition that was used to quantify tissue contrast agent concentration, allowing voxelwise definition of summary DCE‐MRI parameters.ResultsA comparison of reproducibility showed that there was no statistically significant difference in reproducibility between IAUC60 and Ktrans, although there was a trend towards better reproducibility for Ktrans (P = 0.0782). The 95% confidence intervals (CIs) for individual changes showed that for IAUC60 and Ktrans, changes in excess of 47% and 31%, respectively, are outside the range of normal variability.ConclusionAlthough modeling is more complex and more computationally intensive than an IAUC parameterization, our data suggest this approach to be preferable to a model‐free approach since it provides greater physiological insight without a reduction in statistical power for Phase I/II clinical drug trials. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Erythropoietin protects CA1 neurons against global cerebral ischemia in rat: Potential signaling mechanisms
Authors: Zhang Feng , Signore Armando P. , Zhou Zhigang , Wang Suping , Cao Guodong , Chen Jun 
Published: March 2006

AbstractErythropoietin (EPO) is a hormone that is neuroprotective in models of neurodegenerative diseases. This study examined whether EPO can protect against neuronal death in the CA1 region of the rat hippocampus following global cerebral ischemia. Recombinant human EPO was infused into the intracerebral ventricle either before or after the induction of ischemia produced by using the four‐vessel‐occlusion model in rat. Hippocampal CA1 neuron damage was ameliorated by infusion of 50 U EPO. Administration of EPO was neuroprotective if given 20 hr before or 20 min after ischemia, but not 1 hr following ischemia. Coinjection of the phosphoinositide 3 kinase inhibitor LY294002 with EPO inhibited the protective effects of EPO. Treatment with EPO induced phosphorylation of both AKT and its substrate, glycogen synthase kinase‐3β, in the CA1 region. EPO also enhanced the CA1 level of brain‐derived neurotrophic factor. Finally, we determined that ERK activation played minor roles in EPO‐mediated neuroprotection. These studies demonstrate that a single injection of EPO ICV up to 20 min after global ischemia is an effective neuroprotective agent and suggest that EPO is a viable candidate for treating global ischemic brain injury. © 2006 Wiley‐Liss, Inc.
Time course of aquaporin expression after transient focal cerebral ischemia in mice
Authors: de Castro Ribeiro Marlise , Hirt Lorenz , Bogousslavsky Julien , Regli Luca , Badaut Jérôme 
Published: March 2006

AbstractCerebral edema contributes to morbidity and mortality in stroke. Aquaporins (AQPs)‐1, ‐4, and ‐9 have been identified as the three main water channels in the brain. To clarify their role in water movement, we have compared their expression patterns with brain swelling after transient focal brain ischemia. There were two peaks of maximal hemispheric swelling at 1 hr and at 48 hr after ischemia, coinciding with two peaks of AQP4 expression. At 1 hr after occlusion, AQP4 expression was significantly increased on astrocyte endfeet in the core and in the border of the lesion. At 48 hr, AQP4 expression was increased in astrocytes in the border of the lesion over the whole cell. AQP9 showed a significant induction at 24 hr that increased gradually with time, without correlation with the swelling. The expression of AQP1 remained unchanged. These results suggest that AQP4, but not AQP1 or AQP9, may play an important role in water movement associated with the pathophysiology of edema after transient cerebral ischemia in the mouse. © 2006 Wiley‐Liss, Inc.
Non‐galloylated and galloylated proanthocyanidin oligomers in grape seeds from Vitus vinifera L. cv. Graciano, Tempranillo and Cabernet Sauvignon
Authors: Núñez Verónica , Gómez‐Cordovés Carmen , Bartolomé Begoña , Hong Yun‐Jeong , Mitchell Alyson E. 
Published: March 2006

AbstractNon‐galloylated and galloylated flavan‐3‐ol composition in seeds from Vitis vinifera L. var. Graciano, Tempranillo and Cabernet Sauvignon grapes harvested in 2000, 2001 and 2002 at the same geographical area were determined using normal‐phase HPLC coupled with electrospray ionization mass spectrometry (LC/ESI‐MS) detection. Non‐galloylated and monogalloylated flavan‐3‐ols up to octamers, and di‐, and trigalloylated flavan‐3‐ols up to heptamers were identified in all grape seeds. Comparisons of the flavan‐3‐ol composition in three grape varieties harvested in three different years indicate that levels of non‐galloylated flavan‐3‐ols decrease as the degree of polymerization increased, whereas the monogalloylated dimers were present in the highest levels in all varieties and vintages. The levels of other monogalloylated flavan‐3‐ols varied in different vintages. Tempranillo contained the lowest levels of non‐galloylated and monogalloylated flavan‐3‐ols, whereas Graciano contained the highest levels, with the exception of non‐galloylated flavan‐3‐ols in vintage 2001, and non‐galloylated monomers in vintages 2000 and 2002. Grape seeds from vintage 2000 contained the highest levels of both non‐galloylated and galloylated structures. Statistical analyses indicate that the distribution of the flavan‐3‐ols is primarily determined by genetic factors and is also strongly influenced by climate conditions. Copyright © 2006 Society of Chemical Industry
Chemical and sensory stability of roasted high‐oleic peanuts from Argentina
Authors: Nepote Valeria , Mestrallet Marta G , Accietto Ricardo H , Galizzi Melina , Grosso Nelson R 
Published: March 2006

AbstractThe purpose of this work was to determine the chemical and sensory stability of roasted peanuts prepared with a high‐oleic cultivar, Granoleico (GO‐RP), in comparison to a regular cultivar, Tegua (T‐RP), from Argentina. Consumer test of fresh products, oxidative stability estimated by chemical indicators (peroxide and p‐anisidine values, conjugated dienes and trienes) and descriptive analyses during storage (at 23 and 40 °C) were performed on the roasted peanuts. GO‐RP did not differ from T‐RP as regards consumer acceptance. Chemical indicator values and oxidized and cardboard flavors showed lower increments for GO‐RP than T‐RP during storage. Roasted peanutty flavor decreased for both samples at 23 and 40 °C. Using prediction equations, roasted peanuts prepared with kernels of high‐oleic contents had shelf lives of 25 (at 23 °C) and 10 (at 40 °C) times longer than those elaborated with normal peanuts. Copyright © 2006 Society of Chemical Industry
Multi‐dimensional HPLC/MS of the nucleolar proteome using HPLC‐chip/MS
Authors: Vollmer Martin , Hörth Patric , Rozing Gerard , Couté Yohann , Grimm Rudi , Hochstrasser Denis , Sanchez Jean‐Charles 
Published: March 2006

AbstractThe proteome of the human nucleolus was investigated in a single analysis using off‐line strong cation exchange chromatography and microfraction collection combined with HPLC‐chip/MS. The analysis was conducted either as a 1‐D workflow with HPLC‐chip alone or as a 2‐D workflow. Two hundred and six unique proteins were identified in the International Protein Index human database corresponding to 2024 unique tryptic peptides identified in the 2‐D analysis. In contrast, only 34 proteins and 151 corresponding tryptic peptides were found by applying a 1‐D separation strategy. This clearly indicated that the complexity of the samples required the combination of more than one orthogonal separation technique. Stringent database search criteria, including reversal of sequences and therefore better exclusion of false‐positive identifications, were applied for reliable protein identification.
Towards a comprehensive 2‐D‐LC–MS separation
Authors: Venkatramani Cadapakam J. , Patel Anurag 
Published: March 2006

AbstractA comprehensive 2‐D‐LC–MS method has been developed by coupling columns of different selectivity. The primary column eluate is alternately trapped and sampled onto the secondary columns through a guard column interface. When one guard column traps the eluate, the other injects the previously trapped components onto a secondary column. This cycle is repeated throughout the chromatogram. The use of dual secondary columns provides the secondary columns with additional time to generate high‐speed chromatograms. Each secondary column generates alternate chromatograms which when combined generate the entire chromatogram. The primary column separation is comparable to conventional HPLC, whereas the secondary column separation is fast. With both the columns operating in reverse phase mode, one would expect strong correlation in the two‐dimensional retention and hence inefficiency in separation. However, differences in column operation modes, interaction mechanisms, and vendor silica result in a complementary separation. The system was evaluated by comparing it to one‐dimensional counterparts and coupled column chromatography. Although some correlations were observed in 2‐D‐LC–MS, peaks do show two‐dimensional distribution with superior UV and MS data as co‐elution is minimized. Also, the ease of converting conventional systems to 2‐D‐LC–MS is discussed.
Fractionation and separation of human salivary proteins by pH‐gradient ion exchange and reversed phase chromatography coupled to mass spectrometry
Authors: Pepaj Milaim , Holm Anders , Fleckenstein Burkhard , Lundanes Elsa , Greibrokk Tyge 
Published: March 2006

AbstractIn the present work, a 2‐D capillary liquid chromatography method for fractionation and separation of human salivary proteins is demonstrated. Fractionation of proteins according to their pI values was performed in the 1‐D employing a strong anion exchange (SAX) column subjected to a wide‐range descending pH gradient. Polystyrene‐divinylbenzene (PS‐DVB) RP columns were used for focusing and subsequent separation of the proteins in the 2‐D. The SAX column was presaturated with a high pH buffer (A) consisting of 10 mM amine buffering species, pH 9.0, and elution was performed with a low pH elution buffer (B) having the same buffer composition and concentration as buffer A, but pH 3.5. Isoelectric point fractions eluting from the 1‐D column were trapped on PS‐DVB trap columns prior to back‐flushed elution onto the PS‐DVB analytical column for separation of the proteins. The 1‐D fraction eluting at pH 9.0–8.7 was chosen for further analysis. After separation on the RP analytical column, nine RP protein fractions were collected and tryptic digested for subsequent analyses by MALDI TOF MS and column switching capillary LC coupled to ESI TOF MS and ESI QTOF MS. Eight proteins and two peptides were identified in the pH 9.0–8.7 fraction using peptide mass fingerprinting and uninterpreted MS/MS data.
Considerations on the possibilities and limitations of comprehensive normal phase–reversed phase liquid chromatography (NPLC×RPLC)
Authors: François Isabelle , de Villiers André , Sandra Pat 
Published: March 2006

AbstractA comprehensive normal phase system LC‐reversed phase LC (NPLC× RPLC) was evaluated for the separation of a pharmaceutical mixture and citrus oil extracts. NPLC was performed on a 25 cm×1 mm ID×5 μm dp diol phase. In the second dimension, an RP 18 monolithic column (10 cm L×4.6 mm ID×2 μm macropore size) and an octadecyl silicagel‐packed column (5 cm L×4.6 mm ID×3.5 μm dp) were applied for the analyses of the pharmaceutical sample and the citrus oil extracts, respectively. A two‐position/ten‐port switching valve was used as interface. Under optimised LC conditions, the high degree of orthogonality between NP and RP resulted in peak capacities of 300 for the pharmaceutical sample and of 450 for the citrus oil extract composed of lemon and orange oil. Despite the features of NPLC×RPLC, several shortcomings related with the solvent incompatibility between the two LC modes were identified and the practical consequences were discussed.
Influence of Solvents on the Formation of Honeycomb Films by Water Droplets Templating
Authors: Tian Ye , Ding Huaiyu , Jiao Qingze , Shi Yanqiao 
Published: March 2006

AbstractSummary: Several solvents were utilized to investigate their influence on the formation of honeycomb patterns. The polymers PPO, PLGA and PLLGA were dissolved in different solvents or mixed solvents to form porous membranes. It was found that a good compatibility between the polymers and their solvents, and an appropriate volatility of the solvent were beneficial for the formation of regular structures. Moreover, C2HCl3 and CH2Cl2, neither of whose PPO solutions could form regular structures at 30 °C, were mixed at different volume ratios to dissolve PPO and fabricate porous structures. The result showed that a regular pattern was achieved when the volume ratio of C2HCl3:CH2Cl2 was 90:10 and that a special structure with big pores surrounded by small pores was obtained when the volume ratio of C2HCl3:CH2Cl2 was 10:90. Based on these phenomena, possible reasons were also proposed.
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Free Volume, Glass Transition and Degree of Branching in Ethylene/α‐Olefin Copolymers: Positron Lifetime, Differential Scanning Calorimetry, Wide‐Angle X‐Ray Scattering, and Density Studies
Authors: Bamford David , Dlubek Günter , Lüpke Thomas , Kilburn Duncan , Stejny Jarda , Menke Tammo J. , Alam M. Ashraf 
Published: March 2006

AbstractSummary: Positron annihilation lifetime spectroscopy, differential scanning calorimetry, wide‐angle X‐ray scattering, and density measurements were used to systematically study the variation of the glass transition temperature Tg and the mean size vh of holes (local free volumes) in n‐alkyl branched polyethylenes. The samples were commercial ethylene‐rich copolymers with 1‐propene, 1‐butene, and 1‐octene comonomers. From the total specific volume V and the crystallinity Xc the specific volume of the amorphous phase Va was estimated and used to calculate the specific hole‐free volume Vf. It was found that Tg and Xc decrease and V, Va, Vf, and vh increase with increasing weight fraction of comonomers. Both the real crystalline and amorphous specific volumes decrease with increasing crystallinity Xc. For not too high contents of comonomers, Tg decreases and vh increases linearly with the number and with the length of n‐alkyl branches. This behavior was attributed to an increased segmental mobility caused by branching. Both Tg and vh follow linear master curves as a function of the degree of branching if this is defined as the fractional number of carbon atoms in the side chains compared with the total number of carbon atoms. A method for estimating Tg from vh measured at room temperature is shown. The number density of holes Nh shows a slight variation from 0.6 to 0.8 (±0.1) nm−3 with increasing branching.
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Expulsion of Unimers from Polystyrene‐block‐poly(acrylic acid) Micelles
Authors: Gao Lichao , Shi Linqi , Zhang Wangqing , An Yingli , Jiang Xiaowei 
Published: March 2006

AbstractSummary: The pH response of the micelles of polystyrene‐block‐poly(acrylic acid) (PS200‐b‐PAA78) in water is studied using a combination of techniques: static light scattering (SLS), dynamic light scattering (DLS), and transmission electron microscopy (TEM). The structure of the micelles in dilute aqueous solution is dependent on pH. At pH values <2.5, the micelles precipitate. At pH values from 2.5 to 3.5, the micelles associate to form micellar clusters. At pH values ranging from 3.5 to 8.0, the micelles are dynamically frozen. At pH > 8.1, some PS200‐b‐PAA78 unimers gradually escape from the micelles and subsequently re‐associate to form smaller micelles.The pH‐responsive behavior of the PS200‐b‐PAA78 micelles in solution.magnified imageThe pH‐responsive behavior of the PS200‐b‐PAA78 micelles in solution.
Modeling of Atom Transfer Radical Polymerization with Bifunctional Initiators: Diffusion Effects and Case Studies
Authors: Al‐Harthi Mamdouh , Soares João B. P. , Simon Leonardo C. 
Published: March 2006

AbstractSummary: A mathematical model for atom transfer radical polymerization (ATRP) with bifunctional initiators was developed. The model was validated with three case studies in bulk and solution polymerization. We used only polymer yield data to estimate some of the model parameters, while others were obtained from the literature. The model fits the polymer yield data and also predicts weight‐average molecular weights and polydispersities very well. The free volume theory was also incorporated to the model to study the effect of diffusion‐controlled reactions. The adjustable parameters in the free volume theory for the termination, propagation, activation, and deactivation reactions were varied to show the effect on monomer conversion, polymer chain length, and polydispersity. The model shows that diffusion‐limited termination reactions produce polymer with smaller polydispersities, while diffusion‐limited propagation reactions have the opposite effect. Both models, considering and neglecting diffusion effects on the kinetic rate constants, were compared with experimental data. Even though the model predictions for monomer conversion, number‐average molecular weight, and polydispersity are good in both cases, the simulations indicate that diffusion‐controlled reactions can be ignored for the cases studied in the three case studies described in this paper.Comparison between model predictions and experimental data for BA polymerization of number‐average molecular weight in bulk at 90 °C.magnified imageComparison between model predictions and experimental data for BA polymerization of number‐average molecular weight in bulk at 90 °C.