bluuebunny/crossref_metadata_2025 huggingface dataset:
Galerkin technique based on beam functions in application to the parametric instability of thermal convection in a vertical slot
Authors: Papanicolaou N. C. , Christov C. I. , Homsy G. M.
Published: July 2008

A Fourier–Galerkin spectral technique for solving coupled higher‐order initial‐boundary value problems is developed. Conjugated systems arising in thermoconvection that involve both equations of fourth and second spatial orders are considered. The set of so‐called beam functions is used as basis together with the harmonic functions. The necessary formulas for expressing each basis system into series with respect to the other are derived.

The convergence rate of the spectral solution series is thoroughly investigated and shown to be fifth‐order algebraic for both linear and nonlinear problems. Though algebraic, the fifth‐order rate of convergence is fully adequate for the generic problems under consideration, which makes the new technique a useful tool in numerical approaches to convective problems.

An algorithm is created for the implementation of the method and the results are thoroughly tested and verified on different model examples. The spatial and temporal approximation of the scheme is tested. To further validate the scheme, a singular asymptotic expansion is derived for small values of the modulation frequency and amplitude and the numerical and analytic results are found to be in good agreement.

The new technique is applied to the G‐jitter flow, and the Floquet stability diagrams are produced. We obtain the expected alternating isochronous and subharmonic branches and find that stable motions are always isochronous while unstable motions can be either isochronous or subharmonic. The numerical investigation also leads to novel conclusions regarding the dependence of the amplitude of the solutions on some of the governing parameters. Copyright © 2008 John Wiley & Sons, Ltd.
14th International Conference on Finite Elements in Flow Problems
Authors: Christon Mark A. , Coutinho Alvaro L. G. A.
Published: July 2008

This special issue is dedicated to the Fourteenth Finite Elements in Flow Problems Conference held in Santa Fe, New Mexico, on March 24–28, 2007. The papers in this special issue were selected to represent the broad cross‐section of computational fluid dynamics topics ranging from discontinuous Galerkin and stabilized methods to fluid–structure interaction and viscoelastic flows at the 14th meeting. Copyright © 2008 John Wiley & Sons, Ltd.
In allen Zungen
Authors: Finetti Marco
Published: July 2008

Wissenschaft lebt auch von der Vielfalt der Sprachen. Angesichts der Dominanz des Englischen setzt sich die DFG für eine Kultur der Mehrsprachigkeit ein. Gerade in den Geistes‐ und Sozialwissenschaften soll dabei das Deutsche seinen festen Platz haben
Mit Mathematik unters Messer
Authors: Deuflhard Peter
Published: July 2008

Ein Gesicht kann durch Geburt oder Unfall entstellt sein. Die Mund‐Kiefer‐Gesichts‐Chirurgie versucht, vieles zu korrigieren. Bei der Planung der Operationen helfen hochkomplexe Differentialgleichungen und dreidimensionale Visualisierungen
Fjellbirke, Waldgrenze und Klimawandel
Authors: Holtmeier Friedrich‐Karl , Anschlag Kerstin , Broll Gabriele , Brauckmann Hans‐Jörg
Published: July 2008

Überraschende Nachrichten aus Finnisch‐Lappland: Seit 30 Jahren untersuchen Landschaftsökologen die Birkenwälder im Norden Europas. Sie reagieren langsamer als erwartet auf die sich ständig verändernden Standort‐ und Lebensbedingungen
Kosmische Eindringlinge unter Beobachtung
Authors: Keilhauer Bianca , Blümer Johannes
Published: July 2008

Atomkerne, Photonen und Neutrinos regnen unablässig aus dem Weltraum auf die Erde herab. Am Pierre Auger‐Observatorium in Argentinien blicken Forscher mit bisher unerreichter Präzision auf die höchstenergetischen Teilchen – und erhoffen sich dadurch neues Wissen über unser Universum
Influence of Methanol Crossover on the Fuel Utilization of Passive Direct Methanol Fuel Cell
Authors: Lai Q.‐Z. , Yin G.‐P. , Wang Z.‐B. , Du C.‐Y. , Zuo P.‐J. , Cheng X.‐Q.
Published: July 2008

The effect of methanol crossover on the fuel utilization of a passive direct methanol fuel cell (DMFC) was reported. The results revealed that the Faradaic efficiency decreased from 46.9 to 17.4% when methanol concentration increased from 1.0 to 8.0 mol L–1 at the lower current density 11.1 mA cm–2. However, the Faradaic efficiency increased from 14.7 to 31.3% when methanol concentration increased from 1.0 to 8.0 mol L–1 at a higher current density of 44.4 mA cm–2. On the other hand, although the amount of methanol was increased, the Faradaic efficiency did not change, obviously due to the uniform methanol crossover and methanol diffusion at the same methanol concentration and constant current.
Modelling of Proton Diffusion in Immobilised Imidazole Systems for Application in Fuel Cells
Authors: Tölle P. , Cavalcanti W. L. , Hoffmann M. , Köhler C. , Frauenheim T.
Published: July 2008

The mobility of an excess proton has been studied in systems of immobilised imidazole under different conditions using quantum mechanical approaches coupled to a molecular mechanics force field in molecular dynamics. The system is a simple model for imidazole covalently bound to a mesoporous material. Such materials are intended to be used as an additive to a polymer electrolyte membrane for fuel cells. This theoretical work is focused on dynamic properties of the proton transport. The diffusion constant of the system is found to be in the order of magnitude of 10–9 m2 s–1 and it is verified that the proton diffusion increases with increase in temperature or density. Further, the proton transport mechanism is investigated.
Partially Fluorinated Aarylene Polyethers and their Ternary Blends with PBI and H3PO4. Part II. Characterisation and Fuel Cell Tests of the Ternary Membranes
Authors: Li Q. , Jensen J. O. , Pan C. , Bandur V. , Nilsson M. S. , Schönberger F. , Chromik A. , Hein M. , Häring T. , Kerres J. , Bjerrum N. J.
Published: July 2008

Ternary blend membranes based on sulphonated partially fluorinated arylene polyether, polybenzimidazole (PBI) and phosphoric acid were prepared and characterised as electrolyte for high temperature proton exchange membrane fuel cells. Partially fluorinated arylene polyether was first prepared from polycondensation of decafluorobiphenyl with 2,2‐bis(4‐hydroxyphenyl)hexafluoropropane, followed by sulphonation with H2SO4/60% SO3, based on which binary blends with PBI were prepared and further doped with concentrated phosphoric acid at temperatures of up to 130 °C. Acid doping levels as high as 10–13 mol phosphoric acid per PBI repeat unit can be reached, showing small swelling and excellent mechanical strength. At an acid doping level of 11, a conductivity of 0.12 S cm–1 was obtained at 175 °C and 10% relative humidity. Such a membrane exhibits a tensile strength of 6 MPa, elongation of 220% and modulus of 50 MPa at 150 °C. Based on these ternary membranes large MEAs with an active area of 256 cm2 have been prepared for a 2 kWel stack showing good performance and reproducibility.
Phosphotungstic Acid Supported on a Nanopowdered ZrO2 as a Filler in Nafion‐Based Membranes for Polymer Electrolyte Fuel Cells
Authors: Saccà A. , Carbone A. , Pedicini R. , Marrony M. , Barrera R. , Elomaa M. , Passalacqua E.
Published: July 2008

An inorganic filler prepared by impregnation of phosphotungstic heteropolyacid on zirconia (HPW/Zr) was developed to be inserted into a perfluorosulphonic polymer matrix for a polymer electrolyte fuel cell (PEFC) operating at a medium temperature (80–120 °C) and low relative humidity (RH). Two different phosphotungstic acid (PWA) loadings (30 and 45% w/w) were anchored on a nanopowdered ZrO2. Such compounds were characterised by different techniques: differential scanning calorimetry (DSC), X‐ray diffraction (XRD), energy dispersive X‐ray analysis (EDX) and porosity and surface area by Brunauer–Emmett–Teller (BET), to verify the introduction and anchorage of PWA on ZrO2. Two composite Nafion membranes were prepared and characterised in terms of chemical–physical characteristics and electrochemical tests. Thermogravimetric analysis (TGA) provided evidence that HPW/Zr had been incorporated into composite membranes and it was not eluted. A good proton conductivity of about 6 × 10–3 S cm–1 at 120 °C and 25% RH was recorded.

Accelerated in situ ageing tests highlighted a good electrochemical stability (more than 150 cycles at 90 °C with dry gases) of the composite membranes with a slow decay and a reasonable integrity of the analysed membrane‐electrodes assembly (MEA). Finally, a post‐mortem SEM–EDX analysis on MEAs confirmed the presence of HPW/Zr in the membrane after the in situ testing.
Partially Fluorinated Arylene Polyethers and Their Ternary Blend Membranes with PBI and H3PO4. Part I. Synthesis and Characterisation of Polymers and Binary Blend Membranes
Authors: Kerres J. , Schönberger F. , Chromik A. , Häring T. , Li Q. , Jensen J. O. , Pan C. , Noyé P. , Bjerrum N. J.
Published: July 2008

A partially fluorinated polyether ionomer from polycondensation of decafluorobiphenyl with 2,2‐bis(4‐hydroxyphenyl)hexafluoropropane, followed by sulphonation with H2SO4 (60% SO3), has been prepared and optimised in terms of molecular weight and sulphonation degree. The partially fluorinated ionomer has been blended with poly(2,2′‐m‐phenylene‐5,5′‐bibenzimidazole) (PBI), yielding base–acid blends with PBI in excess. The base–acid blend membranes have been characterised in terms of solubility in DMAc, water uptake and oxidative stability by immersion in aqueous 5 wt.‐% H2O2 solutions and Fenton's Reagent, respectively.
Electrophoretic Deposition of Dense Sr‐ and Mg‐Doped LaGaO3 Electrolyte Films on Porous La‐Doped Ceria for Intermediate Temperature Solid Oxide Fuel Cells
Authors: Bozza F. , Polini R. , Traversa E.
Published: July 2008

The application of the electrophoretic deposition (EPD) technique to the preparation of dense La0.8Sr0.2Ga0.8Mg0.2O2.8 (LSGM) electrolyte films for intermediate temperature solid oxide fuel cells (IT‐SOFCs) was investigated. Suspensions of LSGM were prepared in acetone + I2 + H2O dispersion media. The effects of water and iodine content, of the applied voltage, and of powder loading on the EPD rate were systematically studied using metallic substrates (Pt and stainless steel). This allowed to identify the suitable set of EPD process parameters that were used to deposit LSGM films on tape‐cast composite electrodes, composed of lanthanum‐doped ceria (La0.4Ce0.6O2 –x, LDC), polyvinylidene difluoride (PVDF) and carbon powders. After EPD, dense and crack‐free 15 μm thick LSGM films were obtained on porous LDC by co‐firing in air at 1,490 °C. Line profile analyses performed by energy dispersive X‐ray spectroscopy (EDS) did not reveal any interdiffusion of ions across the LSGM/LDC interface. The chemical and structural compatibility of LSGM with LDC was also checked by heat treating a mixture of the two powders (1:1 weight ratio) using the same thermal cycle as that of the LDC/LSGM bi‐layer co‐firing at 1,490 °C. EPD has thus proven to be a viable way for manufacturing anode‐supported LSGM electrolyte films.
Durability Studies of PBI‐based High Temperature PEMFCs
Authors: Yu S. , Xiao L. , Benicewicz B. C.
Published: July 2008

Long‐term durability testing of polybenzimidazole (PBI)‐based polymer electrolyte membrane (PEM) fuel cells was performed using test protocols designed to simulate fuel cell operational situations which may be found in real applications. The fuel cell voltages and phosphoric acid (PA) loss were carefully monitored over thousands of hours and hundreds of cycles. In the typical operating range for high temperature PEM fuel cells (160 °C), the fuel cell voltage degradation rate was 4.9 μV h–1 for steady‐state operation. The PA loss rates were generally low and indicated that long‐term operation (>10,000 h) was possible without significant performance degradation due to PA loss from the membrane. Dynamic durability tests also showed that the PA loss rate from the membrane electrode assemblies (MEAs) depended on cell operating temperature and load conditions. Under all conditions, the PA loss was a relatively small amount of the total PA in the membrane.
Complete Oxidation of Glycerol in an Enzymatic Biofuel Cell
Authors: Arechederra R. L. , Minteer S. D.
Published: July 2008

Glycerol has drawn increasing attention as a prospective fuel because it has many desirable qualities and is abundant due to the fact that it is a by‐product of biodiesel production. Qualities such as nontoxicity, extremely low vapour pressure, low flammability and high energy density make glycerol very appealing as an energy source. Previous research has shown that partial oxidation of glycerol can occur at enzymatic bioanodes of biofuel cells utilising PQQ‐dependent alcohol dehydrogenase (PQQ‐ADH) and PQQ‐dependent aldehyde dehydrogenase (PQQ‐AldDH). In this paper, we describe the use of glycerol for a fuel in an enzymatic biofuel cell that utilizes a three‐enzyme cascade on the anode that can accomplish the complete oxidation of glycerol. The bioanode that was developed contained PQQ‐ADH, PQQ‐AldDH and oxalate oxidase immobilised within a tetrabutylammonium‐modified Nafion membrane. Our previous research has shown that glycerol is an effective fuel with the PQQ‐ADH and PQQ‐AldDH but still was unable to be fully oxidised. With the addition of oxalate oxidase, these glycerol/air biofuel cells have yielded power densities of up to 1.32 mW cm–2, and have the ability to operate at high fuel concentrations. The oxidation products were confirmed with 13C NMR and comprised mainly 13C‐labelled carbonate and glycerate.
Integrated genomic and transcriptional profiling identifies chromosomal loci with altered gene expression in cervical cancer
Authors: Wilting Saskia M. , de Wilde Jillian , Meijer Chris J. L. M. , Berkhof Johannes , Yi Yajun , van Wieringen Wessel N. , Braakhuis Boudewijn J. M. , Meijer Gerrit A. , Ylstra Bauke , Snijders Peter J. F. , Steenbergen Renske D. M.
Published: July 2008

For a better understanding of the consequences of recurrent chromosomal alterations in cervical carcinomas, we integrated genome‐wide chromosomal and transcriptional profiles of 10 squamous cell carcinomas (SCCs), 5 adenocarcinomas (AdCAs) and 6 normal controls. Previous genomic profiling showed that gains at chromosome arms 1q, 3q, and 20q as well as losses at 8q, 10q, 11q, and 13q were common in cervical carcinomas. Altered regions spanned multiple megabases, and the extent to which expression of genes located there is affected remains unclear. Expression analysis of these previously chromosomally profiled carcinomas yielded 83 genes with significantly differential expression between carcinomas and normal epithelium. Application of differential gene locus mapping (DIGMAP) analysis and the array CGH expression integration tool (ACE‐it) identified hotspots within large chromosomal alterations in which gene expression was altered as well. Chromosomal gains of the long arms of chromosome 1, 3, and 20 resulted in increased expression of genes located at 1q32.1‐32.2, 3q13.32‐23, 3q26.32‐27.3, and 20q11.21‐13.33, whereas a chromosomal loss of 11q22.3‐25 was related to decreased expression of genes located in this region. Overexpression of DTX3L, PIK3R4, ATP2C1, and SLC25A36, all located at 3q21.1‐23 and identified by DIGMAP, ACE‐it or both, was confirmed in an independent validation sample set consisting of 12 SCCs and 13 normal ectocervical samples. In conclusion, integrated chromosomal and transcriptional profiling identified chromosomal hotspots at 1q, 3q, 11q, and 20q with altered gene expression within large commonly altered chromosomal regions in cervical cancer. © 2008 Wiley‐Liss, Inc.
CPEB1 regulates β‐catenin mRNA translation and cell migration in astrocytes
Authors: Jones Kendrick J. , Korb Erica , Kundel Mitchell A. , Kochanek Ashley R. , Kabraji Sheheryar , Mcevoy Michael , Shin Chan Y. , Wells David G.
Published: July 2008

A crucial step in directed cell migration is the recruitment of cytoskeletal regulatory and signaling proteins to the leading edge of the cell. One protein localized to the leading edge of a migrating astrocyte is β‐catenin. Using an in vitro wound‐healing assay, we show that the localization of β‐catenin to the leading edge is dependent upon new protein synthesis at the time of wounding. We examined the mRNA encoding β‐catenin for potential regulatory elements and identified a conserved cytoplasmic polyadenylation element in the 3′‐untranslated region (UTR). We now show that the CPE‐binding protein (CPEB1) is expressed in astrocytes and that translation of β‐catenin mRNA is regulated by CPEB1. Further, expression of a mutant CPEB1 protein in astrocytes not only blocks β‐catenin protein localization, it also inhibits cell migration. These findings demonstrate a role for CPEB1‐mediated protein synthesis in the localization of β‐catenin protein to the leading edge of migrating astrocytes and in regulating directed cell motility. © 2008 Wiley‐Liss, Inc.
A new in vitro model of the glial scar inhibits axon growth
Authors: Wanner Ina B. , Deik Andres , Torres Miguel , Rosendahl Andrew , Neary Joseph T. , Lemmon Vance P. , Bixby John L.
Published: July 2008

Astrocytes respond to central nervous system (CNS) injury with reactive astrogliosis and participate in the formation of the glial scar, an inhibitory barrier for axonal regeneration. Little is known about the injury‐induced mechanisms underlying astrocyte reactivity and subsequent development of an axon‐inhibitory scar. We combined two key aspects of CNS injury, mechanical trauma and co‐culture with meningeal cells, to produce an in vitro model of the scar from cultures of highly differentiated astrocytes. Our model displayed widespread morphological signs of astrocyte reactivity, increases in expression of glial fibrillary acidic protein (GFAP), and accumulation of GFAP in astrocytic processes. Expression levels of scar‐associated markers, phosphacan, neurocan, and tenascins, were also increased. Importantly, neurite growth from various CNS neuronal populations was significantly reduced when neurons were seeded on the scar‐like cultures, compared with growth on cultures of mature astrocytes. Quantification of neurite growth parameters on the scar model demonstrated significant reductions in neuronal adhesion and neurite lengths. Interestingly, neurite outgrowth of postnatal neurons was reduced to a greater extent than that of embryonic neurons, and outgrowth inhibition varied among neuronal populations. Scar‐like reactive sites and neurite‐inhibitory patches were found throughout these cultures, creating a patchwork of growth‐inhibitory areas mimicking a CNS injury site. Thus, our model showed relevant aspects of scar formation and produced widespread inhibition of axonal regeneration; it should be useful both for examining mechanisms underlying scar formation and to assess various treatments for their potential to improve regeneration after CNS injury. © 2008 Wiley‐Liss, Inc.
Down‐regulation of neurocan expression in reactive astrocytes promotes axonal regeneration and facilitates the neurorestorative effects of bone marrow stromal cells in the ischemic rat brain
Authors: Shen Li Hong , Li Yi , Gao Qi , Savant‐Bhonsale Smita , Chopp Michael
Published: July 2008

The glial scar, a primarily astrocytic structure bordering the infarct tissue inhibits axonal regeneration after stroke. Neurocan, an axonal extension inhibitory molecule, is up‐regulated in the scar region after stroke. Bone marrow stromal cells (BMSCs) reduce the thickness of glial scar wall and facilitate axonal remodeling in the ischemic boundary zone. To further clarify the role of BMSCs in axonal regeneration and its underlying mechanism, the current study focused on the effect of BMSCs on neurocan expression in the ischemic brain. Thirty‐one adult male Wistar rats were subjected to 2 h of middle cerebral artery occlusion followed by an injection of 3 × 106 rat BMSCs (n = 16) or phosphate‐buffered saline (n = 15) into the tail vein 24 h later. Animals were sacrificed at 8 days after stroke. Immunostaining analysis showed that reactive astrocytes were the primary source of neurocan, and BMSC‐treated animals had significantly lower neurocan and higher growth associated protein 43 expression in the penumbral region compared with control rats, which was confirmed by Western blot analysis of the brain tissue. To further investigate the effects of BMSCs on astrocyte neurocan expression, single reactive astrocytes were collected from the ischemic boundary zone using laser capture microdissection. Neurocan gene expression was significantly down‐regulated in rats receiving BMSC transplantation (n = 4/group). Primary cultured astrocytes showed similar alterations; BMSC coculture during reoxygenation abolished the up‐regulation of neurocan gene in astrocytes undergoing oxygen‐glucose deprivation (n = 3/group). Our data suggest that BMSCs promote axonal regeneration by reducing neurocan expression in peri‐infarct astrocytes. © 2008 Wiley‐Liss, Inc.
The neuropsychological profile in dementia with Lewy bodies and Alzheimer's disease
Authors: Oda Haruhiko , Yamamoto Yasuji , Maeda Kiyoshi
Published: July 2008

Objective

To demonstrate the exact nature of the cognitive profile of dementia with Lewy bodies (DLB) on standardized neuropsychological tests including the Wechsler Adult Intelligence Scale––Revised (WAIS‐R) and the Wechsler Memory Scale––Revised (WMS‐R).

Design

We examined the WAIS‐R and the WMS‐R of 26 patients with probable DLB (based on the Consensus Criteria for the clinical diagnosis of DLB) and of 78 patients with probable Alzheimer's disease (AD) (based on criteria of the National Institute for Neurological and Communicative Disorders and Stroke‐Alzheimer's disease and Related Disorders Association) who were matched to the patients with DLB 3:1 by Mini‐Mental State Examination score.

Results

The DLB group scored significantly lower on the Block Design, Object Assembly and Digit Symbol of WAIS‐R and significantly higher on the Logical Memory I, Verbal Paired Associates I, Logical Memory II, Visual Paired Associates II, Verbal Paired Associates II and Visual Reproduction II of WMS‐R (p < 0.0016 to p < 0.0001). In a comparison between the DLB group and the AD group, a logistic regression analysis revealed that the weighted sum score of the Object Assembly and the Logical Memory II may differentiate DLB from AD with a sensitivity of 0.81 [95% Confidence Intervals (CI) = 0.66–0.96] and a specificity of 0.76 (95% CI = 0.66–0.85).

Conclusions

The WAIS‐R and the WMS‐R can help to differentiate DLB from AD. Copyright © 2008 John Wiley & Sons, Ltd.
Impact of APOE status on cognitive maintenance in healthy elderly persons
Authors: Zehnder Antoinette E. , Bläsi Stefan , Berres Manfred , Monsch Andreas U. , Stähelin Hannes B. , Spiegel René
Published: July 2008

Objective

The ε4 allele, a variant of the apolipoprotein E (ApoE) gene, is the most prominent genetic risk factor for sporadic, non‐familial Alzheimer's disease (AD) currently known. We investigated the impact of the ApoE‐ε4 status on cognitive performance at repeated test administration in elderly non‐symptomatic persons, with a specific focus on practice effects.

Methods

Three hundred and fifty‐five physically and mentally healthy participants of the Basel Study on the Elderly (119 F, 236 M; age 68.3 ± 7.6; years of education 12.7 ± 3.1; Mini‐Mental State scores 29.0 ± 1.0) were grouped into ApoE ε4 carriers and ApoE ε4 non‐carriers (36.9% and 63.1% of the sample, respectively). Participants were assessed at the beginning of the longitudinal study and on average two years later by means of the California Verbal Learning Test (CVLT) and the Consortium to Establish a Registry for Alzheimer's Disease—Neuropsychological Assessment Battery (CERAD‐NAB), a multidimensional cognitive test battery. Baseline and change scores were analyzed with multiple regression procedures and adjusted for age, education and gender; change scores were also adjusted for baseline performance.

Results

The ApoE ε4 non‐carriers showed slightly better performance with regard to most cognitive parameters at baseline. Mean practice effects of the ApoE ε4 non‐carriers in 12 out of 13 CVLT variables and in five out of the nine main CERAD‐NAB variables were above the 50th percentile, while those of the ApoE ε4 carriers were below the 50th percentile in the respective distributions of test–retest change scores.

Conclusions

The ε4 allele of the ApoE gene has a negative impact on cognitive performance, notably on episodic memory functions, in physically and mentally healthy aged persons. Practice effects seen in carriers of the ApoE ε4 were inferior in most areas tested to the effects seen in ApoE ε4 non‐carriers. Further follow‐up of these subjects will help to determine the clinical significance of these findings. Copyright © 2008 John Wiley & Sons, Ltd.
Lithiated alkylidenebis(phosphonates): Reactive phosphorus intermediates in the synthesis of 3‐amino‐1‐alkenylphosphonates
Authors: Grison Claude , Olszewski Tomasz Krzysztof
Published: July 2008

An efficient and stereoselective‐synthesis of 3‐amino‐1‐alkenylphosphonates by a direct procedure involving alkylidene diphosphorylation of nucleophiles followed by a Horner‐‐Emmons olefination of aminoaldehydes is reported. The versatility of the method is illustrated by the preparation of P‐monoglycosyl‐, P‐diglycosyl 3‐aminoalkenyl‐, and alkylphosphonates. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:461–469, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20450
Bis(trifluoroacetyl)phenols and their derivatives in reactions with selected phosphorus(III) compounds
Authors: Sevenard Dmitri V. , Schoth Ralf‐Matthias , Kazakova Olesya , Lork Enno , Röschenthaler Gerd‐Volker
Published: July 2008

The reactivity of bis(trifluoroacetyl)‐phenols toward selected λ3P derivatives was examined. In the case of dialkyl(isocyanato)phosphites, only one of both present trifluoracetyl moieties of substrate was involved. After addition of the phenolic OH moiety across the intermediary formed PN bond, tri‐, tetra‐, and pentacyclic α‐(trifluoromethyl)phosphoranes were produced in a highly diastereoselective reaction. An unusual deoxygenation of the intermediary hydroxyphosphorane was observed reacting 4‐methyl‐2,6‐bis‐(trifluoroacetyl)phenol with diethyl(trimethylsilyl)‐phosphite, and the subsequent hydrolysis gave γ‐hydroxy‐α‐(trifluoromethyl)phoshonate. On the contrary, during the reaction of the O‐silylated phenol with tris(trimethylsilyl)phosphite, a bis‐phosphonate was obtained that underwent heterocyclization to phosphono phosphole system. The mechanistic aspects of the studied reactions, as well as structural features of the synthesized compounds are discussed, based on the multinuclear NMR spectroscopy and X‐ray single crystal investigation data. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:474–482, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20451
Synthesis of symmetric and dissymetric bisperfluoroalkanesulfonylimides and evaluation of their inhibition on bovine carbonic anhydrase
Authors: Benfodda Zohra , Guillen Franck , Blancou Hubert
Published: July 2008

This study describes a synthesis of symmetric and dissymmetric bis[(perfluoroalkane)‐sulfonyl]imides by the reaction of the sodium salt of perfluoroalkanesulfonamide RFSO2NH−Na+ (RF = C4F9, C6F13, C8F17) with hexamethyldisilazane and perfluoroalkanesulfonylfluoride RFSO2F (RF = C4F9, C6F13, C8F17). They are obtained, in two steps, in moderate overall yield. Moreover, this paper provides a study of their inhibition on bovine carbonic anhydrase. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:542–548, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20452
Organtin complexes of 2,5‐dithiobiurea (H2dtbu): The crystal structures of (Ph3Sn)2(dtbu) and [(n‐Bu)2SnCl]2(dtbu)
Authors: Zhang Rufen , Guo Zhifo , Ma Chunlin
Published: July 2008

A series of organotin(IV) complexes of two types, [R3Sn]2(dtbu) (R = PhCH2 1, Ph 2, n‐Bu 3, H2dtbu = 2,5‐dithiobiurea), [R2SnCl]2(dtbu) (R = PhCH2 4, Ph 5, n‐Bu 6) have been synthesized and characterized by elemental analysis, IR, and NMR (1H, 119Sn) spectroscopy. The structures of 2 and 6 have been determined by X‐ray crystallography. Crystal structures show that both complexes 2 and 6 are the symmetric dinuclear unit. Interestingly, supramolecular structures show that complex 2 has formed a linear chain through NH⋅⋅⋅S hydrogen bonding and 6 has formed a two‐dimensional network in perfect bc plane connected through NH⋅⋅⋅Cl hydrogen bonding and nonbonded S⋅⋅⋅S interactions. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:435–442, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20456
Synthesis of organophosphorus derivatives of 2,6‐di‐tert‐butyl‐4‐methylphenol
Authors: Prishchenko Andrey A. , Livantsov Mikhail V. , Novikova Olga P. , Livantsova Ludmila I. , Milaeva Elena R.
Published: July 2008

Convenient procedures for the synthesis of 2,6‐di‐tert‐butyl‐4‐methylphenol (ionol) mono‐, di‐, and triphosphorus derivatives, starting from the readily accessible 3,5‐di‐tert‐butyl‐4‐hydroxybenzaldehyde, are proposed, and some properties of the obtained compounds are presented. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:490–494, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20458
Synthesis and crystal structure of some phosphite, thiophosphite, and amidophosphite copper(I) halide complexes
Authors: Kursheva Lidiya I. , Kataeva Olga N. , Krivolapov Dmitry B. , Gubaidullin Aidar T. , Batyeva Elvira S. , Sinyashin Oleg G.
Published: July 2008

Some Cu(I) halides complexes based on P(III) acid esters,{[(RE)3PCuBr] (where E = O, N, S); R = n‐Pr, i‐Pr, Et2N} were obtained and characterized using IR, 31P NMR spectroscopy, and single crystal X‐ray diffraction. The comparative structural characteristics of complexes with various donor atoms (E = O, N, S) are analyzed. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:483–489, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20459
Dianion cyclization strategy for the synthesis of macrosilaheterocycles
Authors: Singh Maya S. , Singh Pratibha
Published: July 2008

A practical and efficient method for the preparation of silaheterocycles is described. The key step involves the initial formation of symmetrical chiral ditopic ligand, N,N′‐1,2‐cyclohexylenebis(salicylideneimine) followed by sequential deprotonation with NaH to form dianion intermediate, which reacts with diorganodichlorosilanes to furnish dibenzodioxadiazasilamacrocycles. The products were characterized by satisfactory elemental analyses and spectral (IR, 1H, 13C, 29Si NMR, and Mass) studies. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:455–460, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20460
Synthesis of phosphorus‐substituted dialkylamides of organophosphorus acids, containing P–C–N–P moiety
Authors: Prishchenko Andrey A. , Livantsov Mikhail V. , Novikova Olga P. , Livantsova Ludmila I. , Petrosyan Valery S.
Published: July 2008

Reactions of N‐(trimethylsilyl)amino‐methylphosphonates with organophosphorus acid chlorides were studied, which allowed to develop convenient synthetic approaches to novel phosphorus‐substituted dialkylamides of organophosphorus acids, including a P–C–N–P moiety. Certain properties of the resulting compounds are presented. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:495–499, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20468
Synthesis of 2‐element(Si, Ge, P, Fc)‐substituted O,O‐bis(trimethylsilyl) alkylphosphonites and their functionalized derivatives
Authors: Prishchenko Andrey A. , Livantsov Mikhail V. , Novikova Olga P. , Livantsova Ludmila I. , Petrosyan Valery S.
Published: July 2008

Addition of bis(trimethylsiloxy)phosphine to element(Si, Ge, P, Fc)‐substituted alkenes is proposed as convenient procedures for the synthesis of new 2‐element(Si, Ge, P, Fc)‐substituted alkylphosphonites. Also the new functionalized derivatives of these phosphonites including various amino and amido groups as well as certain properties of these compounds are presented. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:500–505, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20469
The valuation of prenatal life in economic evaluations of perinatal interventions
Authors: Simon Judit , Petrou Stavros , Gray Alastair
Published: July 2008

Perinatal interventions delivered during the prenatal period have the potential to directly impact prenatal life. The decision on when to begin ‘counting’ the life of an infant in the calculus has received little attention in previous economic evaluations of perinatal interventions. We illustrate, using data from a recent trial‐based economic evaluation of magnesium sulphate given to women with pre‐eclampsia to prevent eclampsia, how different definitions of when human life commences can have a significant impact upon cost‐effectiveness estimates based on composite outcome measures such as life years or quality‐adjusted life years gained or disability‐adjusted life years averted. Further, we suggest ways in which methods in this area can be improved. Copyright © 2008 John Wiley & Sons, Ltd.
Specialization and competition in dental health services
Authors: Grytten Jostein , Skau Irene
Published: July 2008

The number of specialists within dental health services has increased over the last few years. This raises the issue of how the services should be organized and funded. We describe the effect of one way of organizing the services, which is by relying on competition. In Norway, some oral specialists face real competition with general dental practitioners for the same patients (prosthetists, periodontists and endodontists), while other specialists do not (orthodontists and oral surgeons). The latter specialists have skills that give them exclusive possibilities to practice their profession. We find that competition can be effective for the specialists who experience real competition with general dental practitioners for patients. In situations where real competition does not exist, specialists can obtain market power and raise their fees. Our results are based on an analysis of a representative set of data from general dental practitioners and specialists in Norway. The specialities in which practitioners can exercise market power raise challenges related to the type of public policy that can reduce this market power in an appropriate way, and without involving too large costs for the authorities. Copyright © 2008 John Wiley & Sons, Ltd.
Farnesoid X receptor antagonizes nuclear factor κB in hepatic inflammatory response
Authors: Wang Yan-Dong , Chen Wei-Dong , Wang Meihua , Yu Donna , Forman Barry M. , Huang Wendong
Published: July 2008

The farnesoid X receptor (FXR) is a nuclear receptor that plays key roles in hepatoprotection by maintaining the homeostasis of liver metabolism. FXR null mice display strong hepatic inflammation and develop spontaneous liver tumors. In this report, we demonstrate that FXR is a negative modulator of nuclear factor κB (NF-κB)–mediated hepatic inflammation. Activation of FXR by its agonist ligands inhibited the expression of inflammatory mediators in response to NF-κB activation in both HepG2 cells and primary hepatocytes cultured

in vitro

.

In vivo

, compared with wild-type controls, FXR−/− mice displayed elevated messenger RNA (mRNA) levels of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), interferon-inducible protein 10, and interferon-γ in response to lipopolysaccharide (LPS). Examination of FXR−/− livers showed massive necroses and inflammation after treatment with LPS at a dose that does not induce significant liver damage or inflammation in wild-type mice. Moreover, transfection of a constitutively active FXR expression construct repressed the iNOS, COX-2, interferon-inducible protein 10 and interferon-γ mRNA levels induced by LPS administration. FXR activation had no negative effects on NF-κB-activated antiapoptotic genes, suggesting that FXR selectively inhibits the NF-κB-mediated hepatic inflammatory response but maintains or even enhances the cell survival response. On the other hand, NF-κB activation suppressed FXR-mediated gene expression both

in vitro

and

in vivo

, indicating a negative crosstalk between the FXR and NF-κB signaling pathways. Our findings reveal that FXR is a negative mediator of hepatic inflammation, which may contribute to the critical roles of FXR in hepatoprotection and suppression of hepatocarcinogenesis. (Hepatology 2008;48:1632–1643.)
Role of leisure-time physical activity in nonalcoholic fatty liver disease: A population-based study
Authors: Zelber-Sagi Shira , Nitzan-Kaluski Dorit , Goldsmith Rebecca , Webb Muriel , Zvibel Izabel , Goldiner Ilana , Blendis Laurie , Halpern Zamir , Oren Ran
Published: July 2008

Physical activity (PA) is commonly recommended for nonalchoholic fatty liver disease (NAFLD) patients. However, there is limited evidence on the independent role of PA in NAFLD. The aim of this study was to examine the association between PA and NAFLD. We conducted a cross-sectional study of a subsample (n = 375) of the Israeli National Health and Nutrition Survey. Exclusion criteria were any known etiology for liver disease. Participants underwent an abdominal ultrasound examination; biochemical tests, including leptin, adiponectin, and resistin; and the noninvasive biomarker SteatoTest and anthropometric evaluations. A semiquantitative food frequency questionnaire and a detailed PA questionnaire were administered. Three hundred forty-nine patients (52.7% men, 30.9% primary NAFLD) were included. The NAFLD group engaged in less aerobic, resistance, or other kinds of PA (

P

≤ 0.03). The SteatoTest was significantly lower among subjects engaging in any PA or resistance PA at least once a week (

P

≤ 0.01). PA at least once a week in all categories was associated with a reduced risk for abdominal obesity. Adjusting for sex, engaging in any kind of sports (odds ratio [OR] 0.66, 95% confidence interval [CI] 0.44-0.96 per 1 standard deviation increment in PA score) and resistance exercise (OR 0.61, 95% CI 0.38-0.85) were inversely associated with NAFLD. These associations remained unchanged after adjusting for homeostasis model assessment, most nutritional factors, adiponectin, and resistin. Only the association with resistance PA remained significant with further adjustment for body mass index (OR 0.61, 95% CI 0.44-0.85). Adding leptin or waist circumference to the model eliminated the statistical significance.

Conclusion:

Habitual leisure-time PA, especially anaerobic, may play a protective role in NAFLD. This association appears to be mediated by a reduced rate of abdominal obesity. (Hepatology 2008;48:1791-1798.)
A Mild and Efficient Method for N‐Arylnucleobase Synthesis via the Cross‐Coupling Reactions of Nucleobases with Arylboronic Acids Catalyzed by Simple Copper Salts
Authors: Tao Lan , Yue Yang , Zhang Ji , Chen Shan‐Yong , Yu Xiao‐Qi
Published: July 2008

A simple and efficient copper‐salt catalyzed N‐arylation of nucleobases is reported. In a mixed solvent of MeOH and H2O, the coupling products were obtained in moderate to excellent yields at room temperature within a short time. A variety of substituted N‐aryl nucleobases can be prepared through this procedure.
Three New Isoflavonoids from the Aerial Parts of Ammopiptanthus mongolicus
Authors: Tian Xiao‐Ming , Chen Shi‐Zhong , Tang Li , Tu Peng‐Fei
Published: July 2008

Three new isoflavonoids, namely (±)‐ammopiptanine A (1), ammopiptanine B (2), ammopiptanoside A (3), together with 13 known compounds, were isolated from the aerial parts of Ammopiptanthus mongolicus. Their structures were elucidated on the basis of detailed spectroscopic analyses and by comparison with those of related model compounds. The isoflavonoids described, except formononetin, wistin, daidzein, and calycosin, were isolated from this plant for the first time.
Two New Nitrone Alkaloids from Huperzia serrata
Authors: Gao Wen‐Yun , Li Yi‐Ming , Jiang Shan‐Hao , Zhu Da‐Yuan
Published: July 2008

Two new nitrone alkaloids were isolated from the whole plant of Huperzia serrata (Thunb.) Trev. They are both phlegmarine‐type lycopodium alkaloids with a nitrone moiety. Their structures were elucidated on the basis of spectral evidences, and their configurations were established on the basis of optical rotation, CD, and NOESY‐NMR data.
Secondary Metabolites from the Leaves of Litsea lii var. nunkao‐tahangensis
Authors: Wang Tzu‐Ann , Cheng Ming‐Jen , Lee Shiow‐Ju , Yang Cheng‐Wei , Chang Hsun‐Shuo , Chen Ih‐Sheng
Published: July 2008

Investigation of the leaves extract of Litsea lii var. nunkao‐tahangensis led to the isolation of five new butanolides, litsealiicolide A (1), isolitsealiicolide A (2), litsealiicolide B (3), isolitsealiicolide B (4), and isolitsealiicolide C (5), along with 17 known compounds. Their structures were determined through in‐depth spectroscopic and mass‐spectrometric analyses. Among the isolates, compounds 1 and 2 were cytotoxic against MCF‐7, NCI‐H460, and SF‐268 cell lines in vitro. Compound 5 and isolinderanolide B (6) showed marginal cytotoxic activity against these three cell lines in vitro.
Iridoids from Viburnum cylindricum
Authors: Chen Xiao‐Zhen , Wu Hua‐Fang , Li Guo‐You , Lu Sheng‐Ming , Li Bo‐Gang , Fang Dong‐Mei , Zhang Guo‐Lin
Published: July 2008

Two new iridoids, methyl (+)‐rel‐(1R,3S,4R,5R,8R,9R)‐1,3,4,5,8,9‐hexahydro‐8‐hydroxy‐3‐methoxy‐2H‐1a,2‐dioxacyclopent[cd]indene‐4‐carboxylate (1) and methyl (+)‐rel‐(1R,3S,4S,5R,8R,9R)‐1,3,4,5,8,9‐hexahydro‐8‐hydroxy‐3‐methoxy‐2H‐1a,2‐dioxacyclopent[cd]indene‐4‐carboxylate (2), were isolated from Viburnum cylindricum along with 14 known compounds. Their structures were determined by spectroscopic analyses. This type of iridoids bearing a MeO group at C(3) was discovered for the first time.
Taccalonolides W – Y, Three New Pentacyclic Steroids from Tacca plantaginea
Authors: Yang Jun‐Yun , Zhao Rong‐Hua , Chen Chang‐Xiang , Ni Wei , Teng Fei , Hao Xiao‐Jiang , Liu Hai‐Yang
Published: July 2008

Three new pentacyclic steroids, taccalonolides W–Y (2–4, resp.), have been isolated from the whole plants of Tacca plantaginea. Their structures were elucidated on the basis of spectroscopic methods including extensive 1D‐ and 2D‐NMR experiments.
New Sesquiterpenoids from Ligularia duciformis
Authors: Wang Wen‐Shu , Dai Xia , Hong Li‐Ya , Lu Peng , Feng Jin‐Chao , Jiao Yu‐Guo
Published: July 2008

From the whole plants of Ligularia duciformis, four new sesquiterpenoids, 3β‐acetoxy‐6β‐methoxyeremophila‐7(11),9(10)‐dien‐12,8β‐olide (1), 3β‐acetoxy‐8α‐hydroxy‐6β‐methoxyeremophila‐7(11),9(10)‐dien‐12,8β‐olide (2), 3β‐acetoxy‐10β‐hydroxy‐6β,8β‐dimethoxyeremophil‐7(11)‐en‐12,8α‐olide (3), and 3β‐acetoxy‐6β,8β,10β‐trihydroxyeremophil‐7(11)‐en‐12,8α‐olide (4) were isolated. Their structures were established by high‐field NMR techniques (1H,1H‐COSY, 13C‐APT, HMQC, HMBC, and NOESY) and HR‐ESI‐MS analysis, together with comparison of the spectroscopic data with those of structurally related compounds. In addition, the cytotoxicity of the new compounds against human hepatic cancer cells Bel‐7402, human pneumonic cancer cells A‐549, and human colonic cancer cells HCT‐8 were evaluated, the new compounds showed no cytotoxicity against the three tumor cells (all IC50 values >200 μM).
ent‐Kaurane Diterpenoids from Isodon phyllostachys
Authors: Li Xian , Weng Zhi‐Ying , Li Yong , Pu Jian‐Xin , Huang Sheng‐Xiong , Xiao Wei‐Lie , Sun Han‐Dong
Published: July 2008

Phytochemical investigation of the medicinal plant Isodon phyllostachys led to the isolation of four new ent‐kaurane diterpenoids, phyllostacins F–I (1–4, resp.), together with 11 known compounds, rosthorin A (5), rabdoternin C (6), enmenol (7), oridonin (8), lasiocarpanin (9), xerophilusin B (10), ponicidin (11), macrocalin B (12), phyllostachysin A (13), sculponeatin C (14), and macrocalyxoformin E (15). The structures of the new compounds were established by spectroscopic methods, including extensive 1D‐ and 2D‐NMR analyses. Compounds 1, 2, 7, 10, and 13 were evaluated for their inhibitory activity against K562 and HepG2 cell lines.
Two New Pseudoguaianolides from the Flowers of Parthenium hysterophorus
Authors: Das Biswanath , Reddy Kongara Ravinder , Ravikanth Bommena , Sarma Akella Venkata Subrahmanya , Sridhar Balasubramanian
Published: July 2008

Chemical investigation on two samples of the flowers of Parthenium hysterophorus afforded two new pseudoguaianolides (one from each sample) together with several known constituents. The structures of the new compounds were established by extensive spectroscopic (1D‐ and 2D‐NMR) studies. The X‐ray crystallographic analysis of one of these compounds was also accomplished.
Base Mediated Aromatization of Carbonyl Condensation Products Derived from 2‐(2‐Bromoprop‐2‐enyl)cyclohexanone Derivatives via ‘Intramolecular Unsaturation Transfer’
Authors: Yazıcıoğlu Emre Y. , Akhmedov İdris M. , Tanyeli Cihangir
Published: July 2008

Alkylbenzenes are synthesized for the first time from aliphatic hydrocarbons via an one pot, transition metal‐free coupling approach under basic conditions. The method consists of two steps: condensation of 2‐bromoprop‐2‐enyl‐ or 2‐propargylcyclohexanone with alcohols, amines, or amino alcohols, followed by base treatment (Scheme 1). Phenolic ethers and N‐phenylated polyalkyl aromatic compounds are shown to be in the scope of the demonstrated reaction (Table). The proposed mechanism suggests that the unsaturation in another part of the molecule (propargyl‐group equivalent) is transferred into the cyclohexane ring to yield a benzene ring through a series of prototropic shifts.
Total Enzymatic Synthesis of the Cholecystokinin Octapeptide (CCK‐8)
Authors: Joshi Rajendra , Meng Liping , Eckstein Heiner
Published: July 2008

The enzymatic synthesis of the cholecystokinin octapeptide (CCK‐8) is reported. The target octapeptide CCK‐8 is the minimum active sequence with the same biological activity as naturally occurring cholecystokinin and is a potential therapeutic agent in the control of gastrointestinal function as well as a drug candidate for the treatment of epilepsy and obesity. The protected CCK‐8 was obtained by incubation of Bz‐Arg‐Asp(OEt)‐Tyr‐Met‐OAl and Gly‐Trp‐Met‐Asp(OMe)‐Phe‐NH2 with immobilized α‐chymotrypsin. The Bz‐Arg group was used as an N‐terminal protecting group in the synthesis of the tripeptide fragment. The protected CCK‐8 was treated with trypsin to remove the Bz‐Arg group successfully. Free or immobilized enzymes were used as catalysts. The effect of the acyl donor ester structure, the C(α) protecting group of the nucleophile, reaction media, enzyme, and the carrier of the enzymes on the outcome of the coupling reaction was studied.