bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chitosan Glycerophosphate-Based Semirigid Dexamethasone Eluting Biodegradable Stent
Authors: Bleier Benjamin S. , Paulson David P. , O'Malley Bert W. , Li Daqing , Palmer James N. , Chiu Alexander G. , Cohen Noam A. 
Published: March 2009

Background Chitosan is a polysaccharide derived from chitin deacetylation, which can form a biodegradable matrix capable of reversibly binding dexamethasone. The purpose of this study was to optimize the chitosan formulation to produce a pliable sheet, to assess the innate longevity and inflammatory potential of the polymer, and to study the in vivo rate of dexamethasone release over time. Methods Chitosan glycerophosphate (CGP) sheets were produced with varying degrees of deacetylation (70-100%) and analyzed for structural integrity. Two-squared centimeter sheets of 91.7% deacetylated CGP were mixed with dexamethasone and implanted in 12 rabbit maxillary sinuses. Nasal lavage and peripheral blood samples were tested for dexamethasone levels by enzyme-linked immunosorbent assay (ELISA) over 15 days. Sinuses were examined histologically on postoperative days 3, 7, and 15 for persistence of the stent and degree of inflammation when compared with CGP alone. Results The 91.7% deacetylated CGP formulation was found to have optimal mechanical properties and remained present with moderate degradation and negligible inflammation through postoperative day 15. Dexamethasone levels were detectable in nasal lavage and blood samples through postoperative day 15 and decayed over time (lavage: day 0, 7.70 ± 0.97 ng/mL, and day 15, 2.53 ± 1.71 ng/mL; blood: day 3, 2.51 ± 0.14 ng/mL, and day 15, 1.70 ± 0.36 ng/mL). Conclusion CGP may be used to create a semirigid sheet that is malleable, inert, and capable of eluting steroid over 15 days when implanted intranasally. This material may be used to create a pharmacologically active stent that spontaneously degrades over time.
Structural Determination of a Photochemically Active Diplatinum Molecule by Time‐Resolved EXAFS Spectroscopy
Authors: van der Veen Renske M. , Milne Chris J. , El Nahhas Amal , Lima Frederico A. , Pham Van‐Thai , Best Jonathan , Weinstein Julia A. , Borca Camelia N. , Abela Rafael , Bressler Christian , Chergui Majed 
Published: March 2009

AbstractMetallica: A large contraction of the PtPt bond in the triplet excited state of the photoreactive [Pt2(P2O5H2)4]4− ion is determined by time‐resolved X‐ray absorption spectroscopy (see picture). The strengthening of the PtPt interaction is accompanied by a weakening of the ligand coordination bonds, resulting in an elongation of the platinum–ligand bond that is determined for the first time.magnified image
Organisation of the Biosynthetic Gene Cluster and Tailoring Enzymes in the Biosynthesis of the Tetracyclic Quinone Glycoside Antibiotic Polyketomycin
Authors: Daum Martina , Peintner Iris , Linnenbrink Anton , Frerich Anke , Weber Monika , Paululat Thomas , Bechthold Andreas 
Published: March 2009

AbstractSurprising results regarding the function of methyltransferases and oxygenases: Investigations on oxygenase and methyltransferase genes that are located in the polyketomycin biosynthetic gene cluster of Streptomyces diastatochromogenes Tü6028 shed light into polyketide‐modifying reactions.magnified imagePolyketomycin is a tetracyclic quinone glycoside produced by Streptomyces diastatochromogenes Tü6028. It shows cytotoxic and antibiotic activity, in particular against Gram‐positive multi‐drug‐resistant strains (for example, MRSA). The polyketomycin biosynthetic gene cluster has been sequenced and characterised. Its identity was proven by inactivation of a α‐ketoacyl synthase gene (pokP1) of the “minimal polyketide synthase II” system. In order to obtain valuable information about tailoring steps, we performed further gene‐inactivation experiments. The generation of mutants with deletions in oxygenase genes (pokO1, pokO2, both in parallel and pokO4) and methyltransferase genes (pokMT1, pokMT2 and pokMT3) resulted in new polyketomycin derivatives, and provided information about the organisation of the biosynthetic pathway.
Subcritical Water Reaction Behavior of D‐Glucose as a Model Compound for Biomass Using Two Different Continuous‐Flow Reactor Configurations
Authors: Saito T. , Sasaki M. , Kawanabe H. , Yoshino Y. , Goto M. 
Published: March 2009

AbstractRecently, cellulosic materials have been considered as a useful resource for the recovery of valuable chemicals and liquid fuels, etc. Cellulose is a homopolymer of D‐glucose, which is often used as a model compound for biomass. Reactions of D‐glucose in subcritical water as the reaction solvent were conducted using a single‐flow‐type reactor (S1) and an admixture‐type reactor with feed and preheated‐water flow (S2) at temperatures from 200 to 240 °C, pressures from 15 to 20 MPa, residence times from 40 to 120 s, and initial feed concentrations of 1.5–10 wt %. D‐Glucose was converted into aldehydes, organic acids and furans, with mainly organic acids obtained at 240 °C. D‐Glucose decomposition using reactors S1 and S2 revealed that the conversion rate of D‐glucose was promoted more using S2 than by S1. The yield of furans with S1 was higher than with S2, while the yield of organic acids from S1 was lower than that from S2.
Linker Conjugation Effects in Rhenium(I) Bifunctional Hole‐Transport/Emitter Molecules
Authors: Cleland Deidre M. , Irwin Garth , Wagner Pawel , Officer David L. , Gordon Keith C. 
Published: March 2009

AbstractInterchromophoric communication– when darkness falls: This study investigates the electronic communication between various hole‐transporting (HT) ligands and a rhenium(phenanthroline) centre to which they are coordinated. It is found that when the conjugation within the HT ligand is increased, the energy of a non‐emissive HT ligand electronic transition is sufficiently lowered so that it interacts with, and partially deactivates, emission from the rhenium(phenanthroline) moiety (see figure).magnified imageSpectroscopic, electrochemical and density functional theory (DFT) methods have been employed to investigate a group of [Re(CO)3(HT)(phen)]+ complexes (phen=1,10‐phenanthroline), and in particular the level of electronic communication between various hole‐transporting (HT) ligands and the rhenium centre. Here, the HT ligand consists of a coordinating pyridine connected to dimethylaniline group through a single‐, double‐ or triple‐bond‐connecting system. Electronic absorption, resonance Raman, and steady‐state emission spectroscopy combined with lifetime studies and DFT calculations suggest that multiple dπ(Re)→π*(phen) metal‐to‐ligand charge transfers (MLCTs) exist for each complex, two of which significantly absorb at about 340 and 385 nm, and one that emits at approximately 540 nm. In the complexes containing more‐conjugated HT ligands, non‐emissive intraligand transitions (IL(HT)) exist with energies between the ground and MLCT excited states. The overlap of these IL(HT) transitions and the absorbing MLCT of lowest energy deactivates emission resulting from about 385 nm excitation, and lowers the quantum yield and excited‐state lifetimes of these complexes. Cyclic voltammetry experiments indicate that throughout the series investigated, the highest occupied molecular orbital (HOMO) of each complex is centred on the HT ligand, while the occupied molecular orbitals localised on the rhenium are lower in energy.
Mechanism of the Catalytic Activity of Nucleophiles in the Stepwise Hydrolysis and Condensation Reactions of Tetramethoxysilane
Authors: Ignatyev Igor S. , Montejo Manuel , López González Juan Jesús 
Published: March 2009

AbstractActive ingredients: A model for the simplest hydrolysis reaction is applied to all stages of stepwise hydrolysis and condensation taking place during a sol–gel process. The picture shows the molecular structures of the transition states of the ammonia‐ (left) and OH−‐promoted (right) condensation reactions of two Si(OH)4 molecules, including an additional water molecule.magnified imageThe previously proposed model of the catalytic activity of nucleophiles in the hydrolysis reaction of tetramethoxysilane is expanded to the subsequent stages of hydrolysis, that is, the stepwise hydrolysis of (MeO)4−x(OH)xSi (x=1–3) molecules, and to the condensation reaction of completely hydrolysed species. The estimate of the reaction barrier heights by using the B3LYP and MP2 methods with correlation‐consistent double‐zeta basis sets allows us to predict the catalytic activity of bases for the different steps of hydrolysis and for condensation reactions. In general, the catalytic activity of bases decreases with the number of hydrolysed groups, vanishing in the case of ammonia at x=2 and remaining in the case of the hydroxyl anion up to x=3. In addition, the value of the catalytic activity of NH3 and OH− is of the same order of magnitude for hydrolysis reactions, while the effect of the OH− anion substantially exceeds that of NH3 for condensation reactions.
Hydrogenation of CO2 to Formic Acid Promoted by a Diamine‐Functionalized Ionic Liquid
Authors: Zhang Zhaofu , Hu Suqin , Song Jinliang , Li Wenjing , Yang Guanying , Han Buxing 
Published: March 2009

AbstractAmines to an end: The basic diamine‐functionalized ionic liquid 1,3‐di(N,N‐dimethylaminoethyl)‐2‐methylimidazolium trifluoromethanesulfonate was prepared and used in the hydrogenation of CO2 to formic acid. One mole of the ionic liquid coordinates two moles of formic acid to promote the reaction. Both the ionic liquid and catalyst can be reused directly after their separation from the formic acid produced.magnified image
The pro‐Th2 cytokine IL‐33 directly interacts with invariant NKT and NK cells to induce IFN‐γ production
Authors: Bourgeois Elvire , Van Linh Pham , Samson Michel , Diem Séverine , Barra Anne , Roga Stéphane , Gombert Jean‐Marc , Schneider Elke , Dy Michel , Gourdy Pierre , Girard Jean‐Philippe , Herbelin André 
Published: March 2009

AbstractIL‐33 has recently been identified as a cytokine endowed with pro‐Th2 functions, raising the question of its effect on invariant natural killer T cell (iNKT), which are potent IL‐4 producers. Here, we report a two‐fold increase of iNKT‐cell counts in spleen and liver after a 7‐day treatment of mice with IL‐33, which results from a direct effect, given that purified iNKT cells express the T1/ST2 receptor constitutively and respond to IL‐33 by in vitro expansion and functional activation. Conversely to the expected pro‐Th2 effect, IL‐33 induced a preferential increase in IFN‐γ rather than IL‐4 production upon TCR engagement that depended on endogenous IL‐12. Moreover, in combination with the pro‐inflammatory cytokine IL‐12, IL‐33 enhanced IFN‐γ production by both iNKT and NK cells. Taken together these data support the conclusion that IL‐33 can contribute as a co‐stimulatory factor to innate cellular immune responses.
Human CD4+ invariant NKT cells are involved in antibacterial immunity against Brucella suis through CD1d‐dependent but CD4‐independent mechanisms
Authors: Bessoles Stéphanie , Dudal Sherri , Besra Gurdyal S. , Sanchez Françoise , Lafont Virginie 
Published: March 2009

AbstractHuman invariant NKT (iNKT) cells are a unique subset of T cells, which recognize glycolipids presented by the CD1d. Among the iNKT cells, several functionally distinct subsets have been characterized according to CD4 and/or CD8 co‐receptor expression. The current study is focussed on the CD4+ iNKT cell subset and its role in an anti‐infectious response. We have examined the role of CD4+ iNKT cells on the intracellular Brucella suis growth. Our results indicate that CD4+ iNKT cells impair the intramacrophagic growth of Brucella. This inhibition is due to a combination of soluble and contact‐dependent mechanisms: IFN‐γ is weakly involved while cytotoxic activities such as the induction of the Fas pathway and the release of lytic granules are major mechanisms. The impairment of Brucella growth by CD4+ iNKT cells requires an interaction with CD1d on macrophage surface. Also, we have shown that although CD4 regulates several biological responses of CD4+ iNKT cells, it is not involved in their antibacterial activity. Here, we have shown for the first time that the CD4+ iNKT cell population has antibacterial activity and thus, participates directly in the elimination of bacteria and/or in the control of bacterial growth by killing infected cells.
Towards the Synthesis of 3‐Silapiperidines
Authors: Blaszykowski Christophe , Brancour Célia , Dhimane Anne‐Lise , Fensterbank Louis , Malacria Max 
Published: March 2009

AbstractA straightforward and unprecedented method towards the synthesis of 3‐silapiperidines is described. The key step involves a formal double nucleophilic substitution reaction between the (bromomethyl)dimethylsilyl chloride and a N,C‐sp2‐1,4‐dianionic species generated from N‐monoprotected allylamines. Subsequent functionalizations are also presented.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Redox‐Controlled Dihydroazulene‐Vinylheptafulvene Photoswitch Incorporating Tetrathiafulvalene
Authors: Petersen Michael Åxman , Andersson Asbjørn Sune , Kilså Kristine , Nielsen Mogens Brøndsted 
Published: March 2009

AbstractA derivative of dihydroazulene (DHA) incorporating the redox‐active unit tetrathiafulvalene (TTF) was prepared and investigated for its ability to undergo light‐induced conversion to the vinylheptafulvene (VHF) isomer. The absorption properties of the oxidized species were investigated by spectroelectrochemistry. Photoswitching was investigated as a function of the redox‐state of the TTF unit, i.e., as neutral or as radical cation, and it was found that photoswitching occurred more than twice as efficiently for the neutral species as for the radical cation species, while the thermal back reaction was unaffected. In addition, we have found that the TTF–DHA conjugate is readily converted to an azulene–TTF donor–acceptor conjugate upon treatment with strong base.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Water: A Suitable Medium for the Petasis Borono‐Mannich Reaction
Authors: Candeias Nuno R. , Veiros Luís F. , Afonso Carlos A. M. , Gois Pedro M. P. 
Published: March 2009

AbstractWater was used as the solvent in the Petasis borono‐Mannich reaction. With the use of salicylaldehyde, secondary amines and boronic acids, several alkylaminophenols were obtained in considerably high yields in water. By using the same methodology, 2H‐chromenes were prepared with the use of vinyl boronic acids. The reaction mechanism was studied by DFT calculations, and the results obtained corroborate the solvent effect experimentally observed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Managing evaluation for program improvement at the Wilder Foundation
Authors: Mattessich Paul W. , Mueller Daniel P. , Holm‐Hansen Cheryl A. 
Published: March 2009

AbstractThe authors tell about their heterogeneous 91 person research and evaluation unit at an operating foundation in St. Paul, Minnesota. They focus on evaluation for program improvement, one of several purposes of studies they work on. The three authors write from their different manager positions within the unit. Included are the context of the organization, strategic principles of their work and how it fits into a program improvement model. Mattessich writes as the executive director and details his day‐to‐day evaluation work. Mueller writes as the associate director, who oversees most of the unit's evaluation work, while Holm‐Hansen writes as a consulting scientist who leads a core research team of four to six. © Wiley Periodicals, Inc.
Priority setting in practice: what is the best way to compare costs and benefits?
Authors: Wilson Edward C. F. , Peacock Stuart J. , Ruta Danny 
Published: March 2009

AbstractPrioritising candidates for health‐care expenditure using cost per Quality‐Adjusted Life Year (QALY) is a helpful but insufficient means of ranking alternative uses for scarce health‐care funds at the local level. This is because QALYs do not by themselves capture all criteria decision makers need to take into account. Other criteria such as reducing inequalities, meeting national and local priorities and public acceptability also feature in the decision maker's utility function.Programme budgeting and marginal analysis (PBMA) is an established framework for systematic priority setting in which a ‘weighted benefit score’ for each option is calculated based on all relevant decision‐making criteria. Ranking options as a ratio of cost to benefit is desirable and necessary to ensure efficiency.In this paper we review a number of approaches to scoring costs and benefits of options in a PBMA context. Several approaches rank by benefit score alone, rather than efficiency (cost per unit of benefit). Of those that do rank by efficiency, we discuss the benefits and drawbacks. The optimal approach is far from clear, with each technique having its own strengths and weaknesses. A deliberative approach using summaries of costs and benefits of options as a basis for discussion may be preferable. Copyright © 2008 John Wiley & Sons, Ltd.
Ab initio theory for treating local electron excitations in molecules and its performance for computing optical properties
Authors: Miura Masanori , Aoki Yuriko 
Published: March 2009

AbstractIn this article, as a first step to develop an efficient approximation for predicting the molecular electronic excited state properties at ab initio level, we propose local excitation approximation (LEA). In the LEA scheme, the only local electron excitations within selected substructure (Chromophore) are treated to calculate the targeted excited state wavefunctions, whereas the other electron excitations (local electron excitations in other substructure and charge‐transfer excitations between different regions) are simply discarded. This concept is realized by using the localized molecular orbitals (LMO) localizing on the chromophore substructure. If the targeted transitions show the strong local character and the adequate substructure is selected as chromophore region, the LEA scheme can provide excited state properties without large loss of accuracy. The fatal slowdown of convergence speed of Davidson's iterative diagonalization due to the use of LMO can be avoided by additional transformation of LMOs. To assess the accuracy and efficiency of the LEA scheme, we performed test calculations using various compounds at configuration interaction single (CIS) and time‐dependent Hartree‐Fock (TDHF) level of theory. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2009
Dissociative photoionization of isoprene: experiments and calculations
Authors: Liu Xianyun , Zhang Weijun , Wang Zhenya , Huang Mingqiang , Yang Xibin , Tao Ling , Sun Yue , Xu Yuntao , Shan Xiaobin , Liu Fuyi , Sheng Liusi 
Published: March 2009

AbstractVacuum ultraviolet (VUV) dissociative photoionization of isoprene in the energy region 8.5–18 eV was investigated with photoionization mass spectroscopy (PIMS) using synchrotron radiation (SR). The ionization energy (IE) of isoprene as well as the appearance energies (AEs) of its fragment ions C5H7+, C5H5+, C4H5+, C3H6+, C3H5+, C3H4+, C3H3+ and C2H3+ were determined with photoionization efficiency (PIE) curves. The dissociation energies of some possible dissociation channels to produce those fragment ions were also determined experimentally. The total energies of C5H8 and its main fragments were calculated using the Gaussian 03 program and the Gaussian‐2 method. The IE of C5H8, the AEs for its fragment ions, and the dissociation energies to produce them were predicted using the high‐accuracy energy model. According to our results, the experimental dissociation energies were in reasonable agreement with the calculated values of the proposed photodissociation channels of C5H8. Copyright © 2009 John Wiley & Sons, Ltd.
The analysis of industrial synthetic polymers by electrospray droplet impact/secondary ion mass spectrometry
Authors: Asakawa Daiki , Chen Lee Chuin , Hiraoka Kenzo 
Published: March 2009

AbstractElectrospray droplet impact (EDI)/secondary ion mass spectrometry (SIMS) is a new desorption/ionization technique for mass spectrometry in which highly charged water clusters produced from the atmospheric‐pressure electrospray are accelerated in vacuum by several kV and impact the sample deposited on the metal substrate. In this study, several industrial synthetic polymers, e.g. polystyrene (PS) and polyethylene glycol (PEG) were analyzed by EDI/SIMS mass spectrometry. For higher molecular weight analytes, e.g. PS4000 and PEG4600, EDI/SIMS mass spectra could be obtained when cationization salts are added. For the polymers of lower molecular weights, e.g. PEG300 and PEG600, they could be readily detected as protonated ions without the addition of cationization agents. Anionized PS was also observed in the negative ion mode of operation when acetic acid was added to the charged droplet. Compared to matrix‐assisted laser desorption/ionization (MALDI), ion signal distribution with lower background signals could be obtained particularly for the low‐molecular weight polymers. Copyright © 2009 John Wiley & Sons, Ltd.
Radial distribution of the contributions to band broadening of a silica‐based semi‐preparative monolithic column
Authors: Abia Jude A. , Mriziq Khaled S. , Guiochon Georges A. 
Published: March 2009

AbstractUsing an on‐column local electrochemical microdetector operated in the amperometric mode, band elution profiles were recorded at different radial locations at the exit of a 10 mm id, 100 mm long silica‐based monolithic column. HETP plots were then acquired at each of these locations, and all these results were fitted to the Knox equation. This provided a spatial distribution of the values of the eddy diffusion (A), the molecular diffusion (B), and the resistance to the kinetics of mass transfer (C) terms. Results obtained indicate that the wall region yields higher A values and smaller C values than the central core region. Significant radial fluctuations of these contributions to band broadening occur throughout the exit column cross‐section. This phenomenon is due to the structural radial heterogeneity of the column.
Solid phase extraction of polyhalogenated pollutants from freshwater using chemically modified multi‐walled carbon nanotubes and their determination by gas chromatography
Authors: Abdel Salam Mohamed , Burk Robert 
Published: March 2009

AbstractThis paper describes the application of pristine and chemically modified multi‐walled carbon nanotubes (MWCNTs) as packing materials for the preconcentration and determination of various polyhalogenated organic pollutants, pentachlorophenol, 2,4,5‐trichlorophenol, 3,3′,4,4′‐tetrachlorobiphenyl, and 2,2′,5,5′‐tetrabromobiphenyl from real water samples based on solid‐phase extraction. MWCNTs were chemically modified by octadecyl amine and polyethylene glycol, separately, and the resulting nano materials were used as packing materials for solid phase extraction. Method development, applicability, and suitability of the above mentioned adsorbents for the solid phase extraction were studied. Method development showed great reproducibility and sensitivity, and low limits of detection within a considerable linear range. The regeneration and reusability of the SPE cartridges were studied using Rideau River (Ottawa, Canada) surface water samples and the results showed that cartridges could be used for three cycles of adsorption/desorption with no loss of efficiency. In general, the results suggested that modification of MWCNTs affords a novel class of adsorbents, which could be used for the SPE of various analytes from aqueous solutions with great efficiency, recovery, reproducibility, sensitivity, and precision, within a wide range of analyte concentrations.