bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polarizable empirical force field for nitrogen‐containing heteroaromatic compounds based on the classical Drude oscillator
Authors: Lopes Pedro E. M. , Lamoureux Guillaume , Mackerell Alexander D. 
Published: December 2008

AbstractThe polarizable empirical CHARMM force field based on the classical Drude oscillator has been extended to the nitrogen‐containing heteroaromatic compounds pyridine, pyrimidine, pyrrole, imidazole, indole, and purine. Initial parameters for the six‐membered rings were based on benzene with nonbond parameter optimization focused on the nitrogen atoms and adjacent carbons and attached hydrogens. In the case of five‐member rings, parameters were first developed for imidazole and transferred to pyrrole. Optimization of all parameters was performed against an extensive set of quantum mechanical and experimental data. Ab initio data were used for the determination of initial electrostatic parameters, the vibrational analysis, and in the optimization of the relative magnitudes of the Lennard‐Jones (LJ) parameters, through computations of the interactions of dimers of model compounds, model compound‐water interactions, and interactions of rare gases with model compounds. The absolute values of the LJ parameters were determined targeting experimental heats of vaporization, molecular volumes, heats of sublimation, crystal lattice parameters, and free energies of hydration. Final scaling of the polarizabilities from the gas‐phase values by 0.85 was determined by reproduction of the dielectric constants of pyridine and pyrrole. The developed parameter set was extensively validated against additional experimental data such as diffusion constants, heat capacities, and isothermal compressibilities, including data as a function of temperature. © 2008 Wiley Periodicals, Inc. J Comput Chem 2009
Reduction of Egf signaling decides transition from crown to root in the development of mouse molars
Authors: Fujiwara Naoki , Akimoto Tadashi , Otsu Keishi , Kagiya Tadayoshi , Ishizeki Kiyoto , Harada Hidemitsu 
Published: December 2008

AbstractMouse, rat, and human molars begin to form their roots after the completion of crown morphogenesis. Though several signaling pathways and transcription factors have been implicated in the regulation of molar crown development, relatively little is known about the regulatory mechanisms involved in the transition from crown to root development. Tooth root formation is initiated by the development of Hertwig's epithelial root sheath (HERS) from the cervical loop in the enamel organ. In this study we examined the change in epidermal growth factor (Egf) signaling during this transition process. Immunohistochemical studies showed that the expression of Egf receptors in the enamel organ disappear gradually in the process and are not observed in HERS. Here, to examine the effect of Egf on the transition, we used the organ culture method to examine the root development. In the presence of Egf, stellate reticulum (SR) cells between the inner and outer epithelial layers in the enamel organ actively proliferated and maintained the enamel organ, and the formation of HERS was not observed. On the other hand, in either the absence of Egf or the presence of the inhibitor of Egf receptors, the SR cells disappeared and HERS formation started. Subsequently, root formation proceeded in the culture period. Therefore, disappearance of SR area may be a key event that controls the timing of onset of HERS formation, and Egf may be one of regulatory factors involved in the change from cervical loop epithelium to HERS during root development. J. Exp. Zool. (Mol. Dev. Evol.) 312B:486–494, 2009. © 2008 Wiley‐Liss, Inc.
Intracellular sAPP retention in response to Aβ is mapped to cytoskeleton‐associated structures
Authors: Henriques Ana Gabriela , Vieira Sandra Isabel , Crespo‐López Maria Elena , Guiomar de Oliveira Márcio A. , da Cruz e Silva Edgar F. , da Cruz e Silva Odete A.B. 
Published: December 2008

AbstractAmyloid β (Aβ) contributes to neurodegeneration in Alzheimer's disease and provides a close association between molecular events and pathology, although the underlying molecular mechanisms are unclear. In the work described here, Aβ did not induce amyloid precursor protein (APP) expression, but APP processing/trafficking was markedly affected. In COS‐7 cells, Aβ provokes retention of intracellular sAPPα (isAPPα). Intracellular holo‐APP levels remain unchanged, and extracellular total sAPP increases, although extracellular sAPPα alone was not altered significantly. In primary neuronal cultures and PC12 cells, isAPP also increased, but this was mirrored by a decrease in extracellular total sAPP. The isAPP retention was particularly associated with the cytoskeletal fraction. The retention “per se” occurred in vesicular‐like densities, negative for a C‐terminal antibody and strongly positive for the 6E10 antibody, clearly showing abnormal intracellular accumulation of sAPPα in response to Aβ. Our data support a dynamic model for intracellular retention of sAPPα as an early response to Aβ exposure. Particularly noteworthy was the observation that removal of Aβ reversed the isAPP accumulation. Mechanistically, these findings disclose an attractive physiological response, revealing the capacity of cells to deal with adverse effects induced by Aβ. © 2008 Wiley‐Liss, Inc.
Frequency of extreme rainfall events in Southern Brazil modulated by interannual and interdecadal variability
Authors: Pscheidt Ieda , Grimm Alice Marlene 
Published: December 2008

AbstractThe frequency of extreme rainfall events in Southern Brazil is impacted by El Niño—Southern Oscillation (ENSO) episodes, especially in austral spring. There are two areas in which this impact is more significant: one is on the coast, where extreme events are more frequent during El Niño (EN) and the other one extends inland, where extreme events increase during EN and decrease during La Niña (LN). Atmospheric circulation patterns associated with severe rainfall in those areas are similar (opposite) to anomalous patterns characteristic of EN (LN) episodes, indicating why increase (decrease) of extreme events in EN (LN) episodes is favoured. The most recurrent precipitation patterns during extreme rainfall events in each of these areas are disclosed by Principal Component Analysis (PCA) and evidence the separation between extreme events in these areas: a severe precipitation event generally does not occur simultaneously in the coast and inland, although they may occur inland and in the coastal region in sequence. Although EN predominantly enhances extreme rainfall, there are EN years in which fewer severe events occur than the average of neutral years, and also the enhancement of extreme rainfall is not uniform for different EN episodes, because the interdecadal non‐ENSO variability also modulates significantly the frequency of extreme events in Southern Brazil. The inland region, which is more affected, shows increase (decrease) of extreme rainfall in association with the negative (positive) phase of the Atlantic Multidecadal Variability, with the negative (positive) phase of the Pacific Multidecadal Variability and with the positive (negative) phase of the Pacific Interdecadal Variability. Copyright © 2008 Royal Meteorological Society
The annual cycle of heavy precipitation across the United Kingdom: a model based on extreme value statistics
Authors: Maraun D. , Rust H. W. , Osborn T. J. 
Published: December 2008

AbstractThe annual cycle of extreme 1‐day precipitation events across the UK is investigated by developing a statistical model and fitting it to data from 689 rain gauges. A generalized extreme‐value distribution (GEV) is fit to the time series of monthly maxima, across all months of the year simultaneously, by approximating the annual cycles of the location and scale parameters by harmonic functions, while keeping the shape parameter constant throughout the year. We average the shape parameter of neighbouring rain gauges to decrease parameter uncertainties, and also interpolate values of all model parameters to give complete coverage of the UK. The model reveals distinct spatial patterns for the estimated parameters. The annual mean of the location and scale parameter is highly correlated with orography. The annual cycle of the location parameter is strong in the northwest UK (peaking in late autumn or winter) and in East Anglia (where it peaks in late summer), and low in the Midlands. The annual cycle of the scale parameter exhibits a similar pattern with strongest amplitudes in East Anglia. The spatial patterns of the annual cycle phase suggest that they are linked to the dominance of frontal precipitation for generating extreme precipitation in the west and convective precipitation in the southeast of the UK. The shape parameter shows a gradient from positive values in the east to negative values in some areas of the west. We also estimate 10‐year and 100‐year return levels at each rain gauge, and interpolated across the UK. Copyright © 2008 Royal Meteorological Society
Homogenization of Bulgarian temperature series
Authors: Syrakova Margarita , Stefanova Milena 
Published: December 2008

AbstractThe Standard Normal Homogeneity Test (SNHT) was applied to five sets of temperature series—the four seasonal and the annual mean temperatures, at stations representative for the lowlands of Bulgaria. Series cover periods of about 50 to about 100 years. Fourteen percent of the series passed the test successfully, the others had one or more breaks. The number of breaks in the cold seasons was less than the number of breaks in the warm seasons. On average, 38% of the breaks could not be explained by the stations' history, the percentage being the greatest (almost 50%) for the summer series. The adjustments were in the range (−1.2, 0.9)°C. The average values were negative (about − 0.1 °C) for the winter, spring and summer series, but for the autumn and annual series they were practically zero. The average absolute values for different seasons were between 0.34 and 0.44 °C. Magnitudes of the adjustments were greater in the regions closer to the mountains than in the more flat areas. Most of the inhomogeneities were caused by station relocations. Copyright © 2008 Royal Meteorological Society
Space and time behavior of climatic hazard of low temperature for single rice crop in the mid latitude
Authors: Mariani Luigi , Parisi Simone Gabriele , Cola Gabriele 
Published: December 2008

AbstractRice is a crop of tropical origin and therefore very sensitive to low temperatures, particularly during the crucial phase of floral differentiation. A World survey on climatic hazard of low temperatures during this phase was carried out on the basis of National Centers for Environmental Prediction (NCEP) reanalysis temperature data at 850 hPa. The spatial behavior of risk in analysed areas shows high risk for Australia, moderate one for Europe, South America and East Asia, whereas a very low or null risk is shown for North Africa, South Brazil, Iran, Korea and Louisiana.Results show that the level of risk for many regions of the Boreal hemisphere is substantially lowered after the breakpoint of 1981, whereas a more stable situation of risk is observed in the Austral one and particularly in Australia. A global map of risk was also produced and possible limitations of the selected approach are finally discussed. Copyright © 2008 Royal Meteorological Society
Multilayer tendon slices seeded with bone marrow stromal cells: A novel composite for tendon engineering
Authors: Omae Hiromichi , Zhao Chunfeng , Sun Yu Long , An Kai‐Nan , Amadio Peter C. 
Published: December 2008

AbstractThe ideal scaffold for tendon engineering would possess the basic structure of the tendon, native extracellular matrix, and capability of cell seeding. The purpose of this study was to assess the tissue engineering potential of a novel composite consisting of a decellularized multilayer sliced tendon (MST) scaffold seeded with bone marrow stromal cells (BMSC). BMSC and infraspinatus tendons were harvested from 20 dogs. The tendons were sectioned in longitudinal slices with a thickness of 50 µm. The slices were decellularized, seeded with BMSC, and then bundled into one composite. The composite was incubated in culture media for 14 days. The resulting BMSC‐seeded MST was evaluated by qRT‐PCR and histology. The BMSC viability was assessed by a fluorescent tracking marker. Histology showed that the seeded cells aligned between the collagen fibers of the tendon slices. Analysis by qRT‐PCR showed higher tenomodulin and MMP13 expression and lower collagen type I expression in the composite than in the BMSC before seeding. BMSC labeled with fluorescent tracking marker were observed in the composite after culture. Mechanical testing showed no differences between scaffolds with or without BMSC. BMSC can survive in a MST scaffold. The increased tenomodulin expression suggests that BMSC might express a tendon phenotype in this environment. This new composite might be useful as a model of tendon tissue engineering. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27: 937–942, 2009
Preparation of chelating fibrous polymer by different diamines and study on their physical and chemical properties
Authors: Tahaei P. , Abdouss M. , Edrissi M. , Shoushtari A. M. , Zargaran M. 
Published: December 2008

AbstractThe present work describes a new modification process for producing a chelating ion‐exchanger fibers with a distinct selectivity for toxic heavy metal ions. Acrylic fibers were reacted with different diamine compounds in similar conditions. Modified acrylic fibers were prepared by partial conversion of the nitrile groups into amino groups under two‐step processes. In the first step, the pure liquid diamine was mixed with the fibers and in the second step, water was gradually added to the reaction flask to reach a predetermined 3M concentration at refluxing temperature of 91 °C. The aminated acrylic fibers (AAFs) were used as an ion adsorbent in a series of batch adsorption experiments for removal of chromium(III) and lead (II) ions.Experimental results showed that modified acrylic fiber with tetra methylene diamine (TMD) has the highest Pb(II) ion adsorption capacity. Results also showed aminated acrylic with ethylene diamine (EDA) has the most Cr(III) ion adsorption ability. Solubility tests showed, amination treatments give rise to the intermolecular crosslinkage in all samples. The Freundlich and Langmuir models simulated the adsorption equilibrium data of Cr(III) ions on modified fibers and their constants were determined.
Nanophase hardfaced coatings
Authors: Reisgen U. , Stein L. , Balashov B. , Geffers C. 
Published: December 2008

AbstractThis paper demonstrates the possibility of producing iron‐ or chromium‐based nanophase hardfaced coatings by means of common arc welding methods (TIG, PTA). The appropriate composition of the alloys to be deposited allows to control the structural properties and thus also the coating properties of the weld metal. Specific variations of the alloying elements allow also the realisation of a nanostructured solidification of the carbides and borides with cooling rates that are common for arc surfacing processes. The hardfaced coatings, which had been thus produced, showed phase dimensions of approximately 100–300 nm. Based on the results it is established that the influence of the surfacing parameters and of the coating thickness and thus the influence of the heat control on the nanostructuring process is, compared with the influence of the alloy composition, of secondary importance. The generation of nanoscale structures in hardfaced coatings allows the improvement of mechanical properties, wear resistance and corrosion resistance. Potential applications for these types of hardfaced coatings lie, in particular, in the field of cutting tools that are exposed to corrosion and wear.
Mechanical properties of co‐extruded wear resistant powder metallurgical layers on steel substrates
Authors: Röttger A. , Karlsohn M. , Theisen W. , Silva P. , Weber S. , Pyzalla A. 
Published: December 2008

AbstractMaterials with high resistance against abrasive wear are of interest for many tool applications. For economical reasons, thick coatings of several millimetres are requested. The cladding of these materials to low alloyed substrates is commonly performed using hot isostatic pressing, being a cost intensive process in particular for long products. Thus, a novel manufacturing route via direct hot extrusion of encapsulated bulk steel bars and presintered tool steel powders was recently developed. In this manner, wear resistant claddings of PM tool steels and wear resistant MMC on steel substrates could be processed.Heating to process temperature leads to presintering of the powder and only a weak bonding between the steel substrate and the powdery layer. However, after direct hot extrusion at 1150 °C an interface free of macroscopic defects is formed between both materials. The quality and strength of this bond zone was investigated by micro tensile, 4 point bending and shear tests for different materials combinations. For high strength substrate materials, failure always occurs in the brittle wear resistant layer and not at the interface. These results are in agreement with microstructural investigations, exhibiting a pore‐ and defect‐free interface dominated by interdiffusion processes.
Modell zur Analyse des knöchernen Anwachsverhaltens auf bioaktiv beschichteten Implantatoberflächen
Authors: Lochner K. , Erdmann C. , Lüdtke B. , Hansmann D. , Fulda G. , Labs W. , Neumann H.‐G. , Mittelmeier W. , Bader R. 
Published: December 2008

AbstractAuf dem Gebiet der Knochenregeneration sind transiente und permanente Implantate eine wichtige Therapiesäule in der Orthopädischen Chirurgie. In diesem Zusammenhang sind bioaktive Oberflächen von metallischen Implantaten von besonderer Bedeutung. In der vorliegenden Studie sollte ein In‐vitro‐Testsystem etabliert werden, mit dessen Hilfe die Qualität solcher Oberflächen im Hinblick auf Anwachsen und Besiedelung mit Knochenzellen untersucht werden kann. Dazu wurden speziell gefertigte Klammern aus Reintitan (cp‐Ti) mit verschiedenen bioaktiven Oberflächen (BONIT‐HA®, BONIT®) ausgestattet: In diese Klammern wurden jeweils Spongiosazylinder von definierter Größe eingespannt und das Auswachsverhalten von osteoblasten‐ähnlichen Zellen unter Zellkulturbedingungen beobachtet. Nach 10 Inkubationstagen wurde mittels Rasterelektronenmikroskop (REM) die Ausbreitung der aus der Spongiosa abgeleiteten Zellen beurteilt. Es wurde eine gleichmäßige Besiedelung der BONIT® und BONIT‐HA® beschichteten Flächen festgestellt, im Gegensatz zu HA‐gestrahlten Klammern ohne zusätzliche, elektrochemische Beschichtung (Referenz). Diese Ergebnisse zeigen, dass sich das neu entwickelte In‐vitro‐Testsystem mit humaner Spongiosa eignet, um die Oberflächenbeschaffenheit medizinischer Implantate in Bezug auf die Besiedelung durch osteoblasten‐ähnliche Zellen reproduzierbar qualitativ zu charakterisieren.
On the 4JHH long‐range coupling in 2‐bromocyclohexanone: conformational insights
Authors: Coelho Jakelyne V. , Freitas Matheus P. , Tormena Cláudio F. , Rittner Roberto 
Published: December 2008

Abstract2‐Bromocyclohexanone is a model compound in which a 4JH2, H6 coupling constant is observed, whereas the corresponding 4JH2, H4 is absent. The observed long‐range coupling is not only a result of the known W‐type coupling, in the axial conformation, but also because of the less usual diaxial spin–spin coupling in the equatorial conformer. The carbonyl group plays a determining role in describing the coupling pathway, as concluded by natural bond orbital (NBO) analysis; although the $\sigma _{{\rm C2 - H2}} \rightarrow \sigma \ast_{{\rm C1(O) - C6}}$ and $\sigma_{{\rm C6 - H6}} \rightarrow \sigma \ast_{{\rm C1(O) - C2}}$ interactions in the axial conformer contribute for transmitting the spin information associated with the W‐type coupling, the strong $\sigma_{{\rm C2 - H2}} \rightarrow \pi \ast_{{\rm C = O}}$ and $\sigma_{{\rm C6 - H6}} \rightarrow \pi \ast_{{\rm C = O}}$ hyperconjugations in the equatorial conformer define an enhanced coupling pathway for 4JH2, H6, despite the inhibition of this coupling because of $n_{{\rm O}} \rightarrow \sigma \ast_{{\rm C(O) - C}}$ interaction and the large carbonyl angle. These findings provide the experimental evidence that orbital interactions contribute for the conformational isomerism of 2‐bromocyclohexanone. Copyright © 2008 John Wiley & Sons, Ltd.
Urodynamic findings and functional or anatomical obstructions in children who developed bladder diverticula after reimplantation of the ureter
Authors: Martijn Tilanus , Aart Klijn , Pieter Dik , Laetitia de Kort , Tom de Jong 
Published: December 2008

AbstractObjectiveTo study the clinical and urodynamic parameters of children who developed bladder diverticula (BD) after ureteral reimplantation.Materials and methodsWe have reviewed records of 15 children who underwent ureteric reimplantation, possibly with diverticulectomy between January 1998 and October 2004, who postoperatively developed BD and compared the results with 25 patients, surgically treated for primary vesicoureteric reflux (VUR) without BD development after reimplantation. A total of 737 reimplantations was performed in 492 patients. Of the 15 patients and 25 controls we reviewed voiding history and free uroflowmetry, urodynamic parameters, findings on urethrocystoscopy, VCUG and signs of dysfunctional or anatomical obstruction.ResultsOf the fifteen patients with a postoperative diverticulum, one patient (7%) had an infravesical obstruction in combination with a normal voiding pattern, nine patients (60%) had severe dysfunctional voiding and two patients (13%) had both. Three patients had no infravesical obstruction nor dysfunctional voiding. Urodynamically the mean Pmax postoperatively was 96.8 (cm‐H2O) in the obstructed patients (BD‐group) (in controls 50.0 cm‐H2O) and 95.6 (cm‐H2O) for the dysfunctional voiders (in controls 61.8 cm‐H2O). The difference between the Pmax values of BD‐group and controls was significant on the 95% C.I. (P < 0.01).ConclusionDysfunctional voiding and infravesical obstruction in children appear to be important risk factors for acquired BD. Voiding pressures are significantly higher in patients that developed BD. Cognitive bladder training to normalize voiding pressures should be done before surgery if feasible. Special attention should be paid to the persistence of an infravesical obstruction. Neurourol. Urodynam. 28:241–245, 2009. © 2008 Wiley‐Liss, Inc.