bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Steric Crowding on Porphyrin Conformation and Ring Orientations in a Series of Iron(III) μ‐Oxo Dimers Containing meso‐Nitrooctaethylporphyrins
Authors: Patra Ranjan , Bhowmik Susovan , Ghosh Sudip Kumar , Rath Sankar Prasad 
Published: January 2009

AbstractWe have examined the electronic and geometrical effects of the progressive addition of bulky electron‐withdrawing NO2 groups at the adjacent meso positions of FeIII‐μ‐oxo octaethylporphyrin dimers. The successive addition of mono‐, di‐, tri‐, and tetranitro substituents at the meso positions increases the steric congestion at the periphery, which leads to distortion of the porphyrin macrocycle. The X‐ray structures of four such molecules [Fe(din‐OEP)]2O, [Fe(trn‐OEP)]2O, [Fe(tn‐OEP)]2O (triclinic), and [Fe(tn‐OEP)]2O (monoclinic) have been determined; [Fe(tn‐OEP)]2O authenticates the first structurally characterized oxo‐bridged dimer with a dodecasubstituted and most‐distorted porphyrin reported so far and also shows a significant increase in the Fe–Np and Fe–O distances and the displacement of Fe from mean porphyrin plane. The most important structural feature of the molecules is the very different torsional angles. As the number of nitro group increases, the torsional angles also increase from [Fe(OEP)]2O to [Fe(din‐OEP)]2O and to [Fe(tn‐OEP)]2O. However, in the case of [Fe(trn‐OEP)]2O, the torsional angle is zero, while the angles are very different for both molecules present in the asymmetric unit of [Fe(tn‐OEP)]2O (triclinic). Our study suggests that ruffling accommodates steric congestion at the periphery and thus reduces inter‐ring interactions, which leads to smaller torsional angles. Spectroscopic studies are indicative of strong antiferromagnetic coupling between two high‐spin iron(III) centers. The addition of NO2 groups in the porphyrin macrocycle serves both to protect the reactive meso positions from rapid oxidative attack and also to stabilize both porphyrin and metal against any oxidative degradation during catalysis. [Fe(tn‐OEP)]2O therefore ranks amongst the most‐effective catalyst in the oxygenation process. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Influence of Surface Chemistry on Dehydrogenation in Carbon Cryogel Ammonia Borane Nanocomposites
Authors: Sepehri Saghar , García Betzaida Batalla , Cao Guozhong 
Published: January 2009

AbstractThis paper reports the synthesis and characterization of boron‐ and nitrogen‐modified carbon cryogel (CC) ammonia borane (AB) nanocomposites (BNCC‐AB) for hydrogen storage. Resorcinol–formaldehyde (RF) derived CCs were modified by homogeneous dispersion of AB in RF hydrogel prior to pyrolysis. Nanocomposites were fabricated by immersing CC in the AB solution. Nitrogen sorption analysis, X‐ray photoelectron spectroscopy, and differential scanning calorimetry at multiple heating rates were used to study the structure and dehydrogenation properties of the nanocomposites. The results demonstrated lower dehydrogenation temperatures and reduced activation energies for AB when confined inside pores of B‐ and N‐modified CCs relative to AB when confined in the unmodified CC with the same pore size.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Valence‐Tautomeric RbMnFe Prussian Blue Analogues: Composition and Time Stability Investigation
Authors: Salmon Lionel , Vertelman Esther J. M. , Murgui Carlos Bartual , Cobo Saioa , Molnár Gábor , van Koningsbruggen Petra J. , Bousseksou Azzedine 
Published: January 2009

AbstractThree different stoichiometric forms of RbxMn[Fe(CN)6]y·zH2O [x = 0.96, y = 0.98, z = 0.75 (1); x = 0.94, y = 0.88, z = 2.17 (2); x = 0.61, y = 0.86, z = 2.71 (3)] Prussian blue analogues were synthesized and investigated by magnetic, calorimetric, Raman spectroscopic, X‐ray diffraction, and 57Fe Mössbauer spectroscopic methods. Compounds 1 and 2 show a hysteresis loop between the high‐temperature (HT) FeIII(S = 1/2)–CN–MnII(S = 5/2) and the low‐temperature (LT) FeII(S = 0)–CN–MnIII(S = 2) forms of 61 and 135 K width centered at 273 and 215 K, respectively, whereas the third compound remains in the HT phase down to 5 K. The splitting of the quadrupolar doublets in the 57Fe Mössbauer spectra reveal the electron‐transfer‐active centers. Refinement of the X‐ray powder diffraction profiles shows that electron‐transfer‐active materials have the majority of the Rb ions on only one of the two possible interstitial sites, whereas nonelectron‐transfer‐active materials have the Rb ions equally distributed. Moreover, the stability of the compounds with time and following heat treatment is also discussed.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Hydron‐Transfer Processes Involving an Organotitanium Oxide and Alcohols
Authors: Carbó Jorge J. , González‐del Moral Octavio , Martín Avelino , Mena Miguel , Poblet J.‐M. , Santamaría Cristina 
Published: January 2009

AbstractThermal treatment of the μ3‐alkylidyne complexes [{Ti(η5‐C5Me5)(μ‐O)}3(μ3‐CR)] [R = H (1), Me (2)] with alcohols (Ph3COH, Ph2CHOH, PhCH2OH, Ph2CMeOH, tBuOH,Me2CHOH and MeCH2OH) leads to partial hydronation of the alkylidyne moiety supported on the organometallic oxide [Ti3(η5‐C5Me5)3O3] and formation of the new oxo derivatives [{Ti(η5‐C5Me5)(μ‐O)}3(μ‐CHR)(OR′)] [R = H, R′ = Ph3C (3), Ph2CH (4), Ph2CMe (5), tBu (6); R = Me, R′ = Ph3C (7), Ph2CH (8), Ph2CMe (9), tBu (10), Me2CH (11), MeCH2 (12)]. The μ‐CHR group in these species lies above the Ti3O3 ring while the alkoxide ligand is located below it. To gain insight into the mechanism of these reactions, density functional calculations have been performed on the incorporation of alcohols into the model complexes [{Ti(η5‐C5H5)(μ‐O)}3(μ3‐CR)] [R = H (1H), Me (2H)]. Irradiation of solutions containing 1 and the alcohols leads to the compounds [{Ti(η5‐C5Me5)(μ‐O)}3(μ‐CH2)(OR′)] [R′ = Ph3C (13), Ph2CH (14), Ph2CMe (15), tBu (16)] where the methylene (μ‐CH2) and OR′ ligands are located cis with respect to the Ti3O3 unit. Finally, irradiation of solutions of 1 or 2 and Ph3COH in a 1:2 ratio gives the compounds [{Ti(μ3‐O)}3(η5‐C5Me5)2(μ‐CHR)(OCPh3)2] [R = H (19), Me (20)]. The molecular structures of 3, 5, 10, 11, 15 and 20 have been established by single‐crystal X‐ray analysis.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Pyrazole and Pyrazolyl Complexes of cis‐Bis(2,2′‐bipyridine)chlororuthenium(II): Synthesis, Structural and Electronic Characterization, and Acid‐Base Chemistry
Authors: Jude Hershel , Rein Francisca N. , Chen Weizhong , Scott Brian L. , Dattelbaum Dana M. , Rocha Reginaldo C. 
Published: January 2009

AbstractComplexes of the type cis‐[Ru(bpy)2(Cl)(L)]+ [bpy = 2,2′‐bipyridine; with L = pyrazole (1H), 4‐methylpyrazole (2H), and 3,5‐dimethylpyrazole (3H)] were synthesized and isolated as hexafluorophosphate salts. The molecular structures of these new complexes were fully characterized by 1H NMR spectroscopy and ESI mass spectrometry, and the crystal structure of 3H·PF6 was determined by X‐ray crystallography. Compound 3H·PF6 (C25H24ClF6N6PRu) crystallizes in the monoclinic space group P21/n with a = 12.102(2) Å, b = 16.826(3) Å, c = 13.016(2) Å, β = 92.606(2)°, V = 2647.6(8) Å3, and Z = 4. The crystal structure of 3H reveals the formation of an intramolecular hydrogen bond (2.562 Å) between the pyrazole N(2)–H site and the chloride ligand. The redox and electronic absorption properties of 1H, 2H, and 3H, as well as their deprotonated counterparts [L = pyrazolate (1), 4‐methylpyrazolate (2), and 3,5‐dimethylpyrazolate (3)], were investigated by cyclic voltammetry and UV/Vis spectroscopy. For detailed analysis of the electronic nature of this series of pyrazolyl ligands, the results are discussed along with other relevant cis‐[Ru(bpy)2(X)(Y)]n+ complexes. From spectrophotometric pH titrations, the basicity associated with the coordinated pyrazole/pyrazolate couple in water was found in all three cases to be unusually high, partly owing to the N–H···Cl hydrogen bond that stabilizes the protonated, azole state. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Total Synthesis of (±)‐Quebrachamine via [3+2] Cycloaddition and Efficient Chloroacetamide Photocyclization
Authors: Bajtos Barbora , Pagenkopf Brian L. 
Published: January 2009

AbstractThe total synthesis of (±)‐quebrachamine has been completed in 13 linear steps and 17.8 % overall yield. The indole core was constructed via a formal [3+2] dipolar cycloaddition between a functionalized nitrile and donor‐acceptor cyclopropane, and the synthetically challenging nine‐membered ring was secured by an efficient chloroacetamide photocyclization.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Assessment of CE for the identification of microorganisms
Authors: Petr Jan , Ryparová Olga , Ranc Václav , Hinnerová Petra , Znaleziona Joanna , Kowalska Marta , Knob Radim , Maier Vítězslav , Frébort Ivo , Lemr Karel , Ševčík Juraj 
Published: January 2009

AbstractThe assessment of capillary electrophoresis for separation and identification of microorganisms is described in this article. The work brings a comparison of the application of uncoated capillaries modified with poly(ethylene oxide) and coated capillaries for the separation of model microorganisms Saccharomyces cerevisiae and Escherichia coli with Tris–borate–EDTA and Tris–citrate–fructose as electrolytes. The best separation was achieved in the coated capillary using 1 mM Tris–citrate–fructose buffer, pH 6.9. A simple identification based on the migration time and UV spectrum was found unsatisfactory and thus a method based on a post‐separation cultivation and sequential analysis was developed. Off‐line combination with mass spectrometric analysis with the use of desorption electrospray was shown to be an interesting alternative in a study of microorganisms. Mass spectra allowed distinguishing among analyzed cells.
Depletion of high molecular weight dextran from the red cell surface measured by particle electrophoresis
Authors: Rad Samar , Gao Jie , Meiselman Herbert J. , Baskurt Oguz K. , Neu Björn 
Published: January 2009

AbstractThe reversible aggregation of human red blood cells (RBC) by proteins or polymers continues to be of biological and biophysical interest, yet the mechanistic details governing the process are still being explored. A depletion model has been proposed for aggregation by the neutral polyglucose dextran and its applicability at high molecular weights has been recently documented. In the present study the depletion of high molecular weight dextrans on the red cell surface was measured as a function of polymer molecular mass (40 kDa–28 MDa), ionic strength (5 and 15 mM NaCl) and polymer concentration (≤0.9 g/dL). The experimental data clearly indicate an increasing depletion effect with increasing molecular weight: the effects of medium viscosity on RBC mobility were markedly overestimated by the Helmholtz–Smoluchowski relation, with the difference increasing with dextran molecular mass. These results agree with the concept of polymer depletion near the RBC surface and lend strong support to a “depletion model” mechanism for dextran‐mediated RBC aggregation. Our findings provide important new insight into polymer–RBC interactions and suggest the usefulness of this model for fundamental studies of cell–cell affinity and for the development of new agents to stabilize or destabilize specific bio‐fluids.
Assessment of suspended sediment transport in four alpine watersheds (France): influence of the climatic regime
Authors: Mano Vincent , Nemery Julien , Belleudy Philippe , Poirel Alain 
Published: January 2009

AbstractHigh‐frequency water discharge and suspended sediment concentration (SSC) databases were collected for 3 years on four contrasted watersheds: the Asse and the Bléone (two Mediterranean rainfall regime watersheds) and the Romanche and the Ferrand (two rainfall–snowmelt regime watersheds). SSCs were calculated from turbidity recordings (1‐h time step), converted into SSC values. The rating curve was calculated by means of simultaneous SSC measurement taken by water sampling and turbidity recording. Violent storms during springtime and autumn were responsible for suspended sediment transport on the Asse and the Bléone rivers. On the Ferrand and the Romanche, a large share of suspended sediment transport was also caused by local storms, but 30% of annual fluxes results from snowmelt or icemelt which occurred from April to October. On each watershed, SSC up to 50 g l−1 were observed. Annual specific fluxes ranged from 450 to 800 t km−2 year−1 and 40–80% of annual suspended sediment fluxes occurred within 2% of the time. These general indicators clearly demonstrate the intensity of suspended sediment transport on these types of watersheds. Suspended sediment fluxes proved to be highly variable at the annual scale (inter‐annual variability of specific fluxes) as well as at the event scale (through a hysteresis loop in the SSC/Q relationship) on these watersheds. In both cases, water discharge and precipitations were the main processes involved in suspended sediment production and transport. The temporal and spatial variability of hydro‐meteorological processes on the watershed provides a better understanding of suspended sediment dynamics. Copyright © 2009 John Wiley & Sons, Ltd.
Combining the dissipation method and surface renewal analysis to estimate scalar fluxes from the time traces over rangeland grass near Ione (California)
Authors: Castellví F. , Snyder R. L. 
Published: January 2009

AbstractThe dissipation method, the method preferred for estimating scalar surface fluxes over open water has not traditionally been used by agronomists, whereas the surface renewal (SR) theory in conjunction with the analysis of the scalar time trace offers tremendous advantages for estimating fluxes over agronomic crops. For a steady and horizontally homogeneous flow, it is shown that the dissipation method and SR analysis are closely related. As a consequence, a new dissipation–SR analysis expression for estimating scalar surface fluxes was derived. The new equation requires no calibration, and the scalar time trace measured at a frequency capable of identifying canopy‐scale coherent structures (typically 4–10 Hz in agriculture) is the only input required. Sensible and latent heat flux estimates obtained from 10 Hz air temperature and water vapour concentration measurements in the inertial sub‐layer (2 m height) over short, homogeneous rangeland grass at a site where similarity does not hold gave similar results to those measured with the eddy covariance (EC) method. For unstable cases, the new equation provided a root mean square error of 57 W m−2 for the surface energy‐balance closure. For stable cases, the performance was difficult to evaluate because the EC fluxes were similar in magnitude to the sensor error. It is concluded that the proposed method can contribute to a better understanding of hydrological processes and water requirements by providing an accurate, less costly, alternative method to indirectly estimate evapotranspiration as the residual of the energy balance equation. Copyright © 2009 John Wiley & Sons, Ltd.
Snow ablation energy balance in a dead forest stand
Authors: Boon Sarah 
Published: January 2009

AbstractForest disturbance has a significant impact on hydrology due to its effect on the forest canopy, which is important for precipitation interception, transpiration, site micrometeorology, and snow accumulation and ablation. This study examines the impact of mountain pine beetle infestation and subsequent forest death on snow ablation. Dead stands experience needle loss and canopy reduction due mainly to the loss of small branches and stems, which has a subsequent impact on micrometeorological conditions. Ablation is driven largely by incoming short‐wave radiation, which in dead stands is greater than in alive stands, but does not reach that available in clearcuts. Long‐wave radiation emission in dead stands is lower than that in alive stands, reducing its contribution to snowpack warming and ablation. Turbulent flux contributions to snow ablation are limited in forest stands relative to clearcuts, although they are slightly greater in dead than alive stands due to the more open forest structure. Additional studies are required to refine the basic energy balance model and incorporate all processes affecting the snow ablation energy balance. Copyright © 2009 John Wiley & Sons, Ltd.
Biocompatibility and in vivo evaluation of oligochitosans as cationic modifiers of alginate/Ca microcapsules
Authors: De Castro Maria , Orive Gorka , Hernández Rosa M. , Bartkowiak Artur , Brylak W. , Pedraz José L. 
Published: January 2009

AbstractThe present article investigates the substitution of poly‐L‐lysine by two different oligochitosans as membrane‐coating capsule, and its effect on different functionality parameters of cell microencapsulation. To address this issue, initially the biocompatibility of the two types of oligochitosan solutions was evaluated using erythropoietin secreting C2C12 myoblast cell line as model. In a second step, we encapsulated the cells within alginate microcapsules coated with each oligochitosan and a complete morphological and mechanical evaluation was performed. Finally, the in vivo functionality of the enclosed cells in the alginate‐oligochitosan microcapsules was studied in Balb/c mice. Results show that both oligochitosans were biocompatible, not detecting statistical differences between them. The alginate‐oligochitosan microcapsules were totally spherical and uniform and resulted in high hematocrit levels after subcutaneous implantation in mice. In fact, significantly higher hematocrit levels were found in the animals transplanted with the encapsulated cells compared with the control group. Finally, the histological analysis showed a mild fibroblastic reaction around the capsule membrane. These results suggest that alginate‐oligochitosan capsules may be an interesting alternative to conventional alginate‐ poly‐L‐lysine capsules. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Long‐term therapeutic effect of novel calcium phosphate‐based compounds injected in ovariectomized rats
Authors: Tokudome Yoshihiro , Otsuka Makoto , Ito Atsuo , LeGeros Racquel Z. 
Published: January 2009

AbstractThe specific aim of this study was to evaluate the efficacy of well‐characterized Mg/Zn/F‐CaP preparations (administered by injection) in preventing bone mineral deficiency in ovariectomized (OVX) rats. Donryu rats (4 weeks old, average weight 70 g) were divided into six experimental groups: GN (normal), GC (control, OVX), and OVX rats injected with suspensions of MZF‐CaPs (G2, G3, and G4) or with Zn‐containing tricalcium phosphate (ZnTCP, G1). The composition of the preparations was G1: 34.1 wt % Ca; 19.5 wt % P; and 6.17 wt % Zn; G2 (#51): 23.7 wt % Ca; 13.6 wt % P; 1.1 wt % Mg; 2.9 wt % Zn, and 1.1 wt % F; G3 (#68): 22.4 wt % Ca; 14.1 wt % P; 2.6 wt % Mg, 2.6 wt % Zn, and 2.3 wt % F; G4 (#76): 28.5 wt % Ca; 15.5 wt % P; 1.9 wt % Mg, 1.8 wt % Zn, and 3.0 wt % F. The suspensions (10 mg/0.2 mL) were injected into the right thigh once a week for 12 weeks. Bone mineral density (BMD) was measured by X‐ray computed tomography and bone mechanical strength (BMS) was measured as femoral three‐point bending strength. BMD and BMS were significantly higher in the femurs from groups G1, G2, G3, and G4 than from GC. No significant difference was observed in BMD or BMS between the left and right femurs for any group. The results indicate that the injected Mg/Zn/F‐CaP compounds were effective in preventing bone loss induced by ovariectomy in rats and suggest that these compounds have potential use for treating osteoporosis. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
Physically crosslinked composite hydrogels of PVA with natural macromolecules: Structure, mechanical properties, and endothelial cell compatibility
Authors: Liu Y. , Vrana N. E. , Cahill P. A. , McGuinness G. B. 
Published: January 2009

AbstractPolyvinyl alcohol (PVA) hydrogels have been considered potentially suitable for applications as engineered blood vessels because of their structure and mechanical properties. However, PVA's hydrophilicity hinders its capacity to act as a substrate for cell attachment. As a remedy, PVA was blended with chitosan, gelatin, or starch, and hydrogels were formed by subjecting the solutions to freeze‐thaw cycles followed by coagulation bath immersion. The structure‐property relationships for these hydrogels were examined by measurement of their swelling, rehydration, degradation, and mechanical properties. For the case of pure PVA hydrogels, the equilibrium swelling ratio was used to predict the effect of freeze thaw cycles and coagulation bath on average molecular weights between crosslinks and on mesh size. For all hydrogels, trends for the reswelling ratio, which is indicative of the crosslinked polymer fraction, were consistent with relative tensile properties. The coagulation bath treatment increased the degradation resistance of the hydrogels significantly. The suitability of each hydrogel for cell attachment and proliferation was examined by protein adsorption and bovine vascular endothelial cell culture experiments. Protein adsorption and cell proliferation was highest on the PVA/gelatin hydrogels. This study demonstrates that the potential of PVA hydrogels for artificial blood vessel applications can be improved by the addition of natural polymers, and that freeze‐thawing and coagulation bath treatment can be utilized for fine adjustment of the physical characteristics. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
Novel fabrication of PCL porous beads for use as an injectable cell carrier system
Authors: Lim Sung Mook , Lee Hyo Jung , Oh Se Heang , Kim Jin Man , Lee Jin Ho 
Published: January 2009

AbstractInjectable polycaprolactone (PCL) porous beads were fabricated for use as cell carriers by a novel isolated particle‐melting method (for nonporous beads) and the following melt‐molding particulate‐leaching method (for porous beads). The prepared beads showed highly porous and uniform pore structures with almost the same surface and interior porosities (porosity, over 90%). The PCL porous beads (bead size, 400–550 μm) with different pore sizes (25–50 and 50–100 μm) were compared for their in vitro cell (human chondrocyte) growth behavior with the nonporous beads. The porous beads showed higher cell seeding density and growth than the nonporous beads. The pore size effect between the porous beads was not significant up to 7 days, but after that time the beads with pore sizes of 50–100 μm showed significantly higher cell growth than those of 25–50 μm. To evaluate the tissue compatibility of the PCL porous beads, the beads were dispersed, uniformly, in cold Pluronic F127 solution and injected into hairless mice, subcutaneously, in the gel state of Pluronic F127 at room temperature, leading to the homogeneous bead delivery. The histological findings confirmed that the PCL porous beads in Pluronic F127 gel are biocompatible: surrounding tissues gradually infiltrated into the porous beads for up to 4 weeks with little inflammatory response. The PCL porous beads with highly porous and uniform pore structures fabricated in this study can be widely applicable as cell carriers. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009