bluuebunny/crossref_metadata_2025 huggingface dataset:
The boundary layer phenomena in two‐dimensional transversely isotropic piezoelectric media by exact symplectic expansion
Authors: Leung A. Y. T. , Xu Xinsheng , Gu Qian , Leung C. T. O. , Zheng J. J.
Published: August 2006

A separable variable method is introduced to find the exact homogeneous solutions of a two‐dimensional transversely isotropic piezoelectric media to handle general boundary conditions. The usual method of separable variables for partial differentiation equations cannot be readily applicable due to the tangling of the unknowns and their derivatives. Introducing dual variables of stresses, we obtain a set of first‐order Hamiltonian equations whose eigensolutions are symplectic spanning over the solution space to cover all possible boundary conditions. The solutions consist of two parts. The first part is the derogative zero‐eigenvalue solutions of the Saint Venant type together with all their Jordan chains. The second part is the decaying non‐zero‐eigenvalue solutions describing the boundary layer effects. The classical solutions are actually the zero‐eigenvalue solutions representing the simple extension, bending, equipotential field, and the uniform electric displacement. On the other hand, the non‐zero‐eigenvalue solutions represent the localized solutions, which are sensitive to the boundary conditions and are decaying rapidly with respect to the distance from the boundaries. Some rate‐of‐decay curves of the newly found non‐zero‐eigenvalue solutions are shown by numerical examples. Finally, the complete boundary layer effects are quantified for the first time. Copyright © 2006 John Wiley & Sons, Ltd.
Synergistically modified unsaturated polyester resin with polyester urethane and montmorillonite: microstructure and properties
Authors: Wang Cai , Pan Zelin , Zhang Linwen , Yang Dexu , Li Weizhong
Published: August 2006

Microstructure, reacting degree and main properties of synergistically modified unsaturated polyester resin (UPR) with polyester urethane (PU) and organically‐modified montmorillonite (OMT) are studied in this paper by scanning electron microscopy (SEM), X‐ray diffraction (XRD), FT‐IR, contact angle and mechanical properties. The research shows good compatibility of PU with natural fibre and that the contact angle of modified UPR and natural fibre is decreased. Nanocomposites are made using OMT and the impact section of synergistically modified UP composites with PU and OMT shows the toughness breaking. With the increased addition of PU and OMT, the impact strength is increased, the flexural modulus and the cured shrinkage rate are decreased. The testing of mechanical properties shows that when the content of PU is 5% and that of OMT is 1%, the impact strength is increased 80% or above, the decrease of flexural modulus is less than 20% and the cured shrinkage rate is less than 4%. A PU and OMT system was found to have a synergistic effect on the toughness of UPR. Copyright © 2006 John Wiley & Sons, Ltd.
Electrochemical characters of cross‐linkable oligo(oxyethylene) branched low molecular weight poly(organophosphazenes)
Authors: Zhou Shuhua , Fang Shi‐Bi
Published: August 2006

The ionic conductivities of all‐solid polymer electrolytes prepared by UV irradiation crosslinkable oligo(oxyethylene) branched low molecular weight poly(organophosphazenes) macromonomers are reported. The dimensional stability of the poly(organophosphazes) electrolytes was improved by crosslinking. The temperature dependence of ionic conductivity of the all‐solid polymer electrolytes followed the Vogel–Tamman–Fulcher equation. Furthermore, the effects of the length of the oligo(oxyethylene) chain and the degree of crosslinking on the ionic conductivity of the polymer electrolytes are discussed. The stability of the lithium electrode and the all‐solid polymer electrolytes interface were evaluated by measuring the alternating current impedance on symmetric cells. The maximum ionic conductivity of the all‐solid polymer electrolyte was obtained as high as 2.92 × 10−4 sec/cm at 25°C. Copyright © 2006 John Wiley & Sons, Ltd.
Ionic conductivity of chitosan membranes and application for electrochemical devices
Authors: Winie Tan , Majid S. R. , Khiar A. S. A. , Arof A. K.
Published: August 2006

Lithium (Li+)‐ and proton (H+)‐conducting chitosan‐based electrolytes have been prepared using the solution cast technique. The experimental results obtained using chitosan as the host polymer are compared with those of other Li+‐ and H+‐complexes. The Rice and Roth model was used to explain the variations in the conductivity observed. The exponent, n, in Joncsher's universal power law equation σ(ω) = σdc + A′ωn was analyzed as a function of temperature for the chitosan sample containing 41 vol% H3PO4. The analysis suggests that the conduction mechanism follows that proposed by the overlapping large polaron tunneling model. The chitosan membranes can be used as electrolytes in solid state batteries, electric double layer capacitors and fuel cells. However, there is still scope for improvement. Copyright © 2006 John Wiley & Sons, Ltd.
Hexanoyl chitosan‐based gel electrolyte for use in lithium‐ion cell
Authors: Winie Tan , Arof A. K.
Published: August 2006

Hexanoyl chitosan that exhibited solubility in tetrahydrofuran (THF) was prepared by acyl modification of chitosan. Films of hexanoyl chitosan‐based polymer electrolyte were prepared by the technique of solution casting. The effect of plasticizers on the transport properties of hexanoyl chitosan‐lithium trifluoromethanesulfonate (LiCF3SO3) electrolytes have been investigated. The plasticizers used were ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC) and a mixture of DEC/EC and PC/EC. The conductivity is found to be higher for the dual plasticizer system than the single plasticizer system. The highest room temperature conductivity achieved in the DEC/EC and PC/EC dual plasticizer systems is 4.26 × 10−5 and 1.09 × 10−4 S cm−1, respectively. FT‐IR spectroscopic data has been used to interpret the conductivity trend observed. Transport properties such as charge carrier concentration and diffusion coefficient of cation have been calculated to obtain information that may be used to elucidate the mechanism of conductance. Electrochemical cells based on LiCoO2/mesocarbon microbeads (MCMB) couple were assembled using the electrolyte that gave the highest ionic conductivity. The performance of the fabricated cell has also been studied and discussed. Copyright © 2006 John Wiley & Sons, Ltd.
Preparation and characterization of self‐dispersible polymeric microspheres
Authors: Min Ke , Lan Jin , Hu Jianhuan , Wang Changchun
Published: August 2006

Monodispersed OEGMA/St polymeric particles were prepared through soap‐free emulsion polymerization, then surface modification was conducted by atom transfer radical polymerization (ATRP), and nano‐size hairy shell of OEGMA/St particles were obtained. By hydrolysis, the grafting chains of the hairy particles were successfully cut down from the core particles. Through gel permeation chromatography (GPC) and transmission electron microscopy (TEM) measurements, the density of grafting chains was calculated. Experimental results showed that the hairy shell on the surface of the particles could dramatically improve the particles dispersibility in organic solvents. Copyright © 2006 John Wiley & Sons, Ltd.
Complementary/alternative medicine use in a pediatric oncology unit in Turkey
Authors: Karadeniz Ceyda , Pınarlı F. Güçlü , Oğuz Aynur , Gürsel Türkiz , Canter Berna
Published: August 2006

Background

Important in the cancer therapy is the increasingly use of complementary/alternative medicine (CAM). The current study aims to establish the extent of use, the types of therapies employed, factors influencing, the reasons for choosing and the cost of CAM used in pediatric cancer patients in our clinic in Ankara, Turkey.

Procedure

A detailed questionnaire regarding demographic data and information about the use of CAM was completed by 95 patients who have attended the clinic between 1999 and 2000.

Results

Forty‐nine patients (51.6%) had used one or more than one type of CAM. The most frequent (71.4%) was herbal medicine and biologic intake (stinging nettle, plant essence, honey of Anzer). The second one was religious therapy (40.8%). No correlation could be found between the use of CAM and parents education status, the level of income, number of siblings, the prognosis of the disease, the rate of satisfaction with the level of information given by the doctor at the time of diagnosis or the belief in the information given by the doctor about the prognosis (P > 0.05). All patients used CAM in addition to conventional therapy.

Conclusions

More than half of the patients used CAM, with stinging nettle being the most common agent. Our patients place a high level of trust in their physicians and the conventional therapies offered by them; however, they also believe that the complementary therapies are harmless and, therefore, worth trying. Pediatr Blood Cancer 2007;48:540–543. © 2006 Wiley‐Liss, Inc.
Bupropion in pregnancy and the prevalence of congenital malformations
Authors: Cole J. Alexander , Modell Jack G. , Haight Barbara R. , Cosmatos Irene S. , Stoler Joan M. , Walker Alexander M.
Published: August 2006

Purpose

Reports from the GlaxoSmithKline Bupropion Pregnancy Registry suggested an increase in cardiovascular defects following exposure to bupropion during pregnancy. We conducted a study of congenital malformations among infants born to women exposed to bupropion during their first trimester.

Methods

The study used data from UnitedHealthcare between January 1995 and September 2004. We calculated the prevalence of all congenital malformations and cardiovascular malformations associated with bupropion exposure in the estimated first trimester (1213 infants), compared with (1) other antidepressant exposure in the first trimester (4743 infants) and (2) bupropion exposure outside the first trimester (1049 infants). Malformation cases were confirmed through medical record abstraction. We calculated adjusted odds ratios (AORs) using the GEE form of logistic regression.

Results

For all congenital malformations, the prevalence associated with bupropion first trimester was 23.1 per 1000 infants. The AORs were 0.95 (95%CI 0.62–1.45) and 1.00 (95%CI 0.57–1.73) in comparison to other antidepressants (prevalence 23.2 per 1000) and bupropion outside the first trimester (prevalence 21.9 per 1000), respectively. For cardiovascular malformations, the prevalence associated with bupropion first trimester was 10.7 per 1000 infants. The AORs were 0.97 (95%CI 0.52–1.80) and 1.07 (95%CI 0.48–2.40) in comparison to other antidepressants (prevalence 10.8 per 1000) and bupropion outside the first trimester (prevalence 9.5 per 1000), respectively.

Conclusions

Results do not support a hypothesis of a teratogenic effect of first trimester bupropion exposure. The prevalence of malformations associated with bupropion exposure in the first trimester was not increased relative to the comparison groups. Copyright © 2006 John Wiley & Sons, Ltd.
Vinyl copolymers containing pendant 1,4‐distyrylbenzene and 1,3,4‐oxadiazole chromophores: Preparation and optoelectronic properties
Authors: Yeh Kun‐Ming , Chen Yun
Published: August 2006

We prepared two vinyl copolymers P1 and P2 containing pendant distyrylbenzene and aromatic 1,3,4‐oxadiazole derivatives, respectively, from their precursor poly(styrene‐ran‐4‐vinylbenzyl chloride) (Mw = 11,400, PDI = 1.18), which had been prepared by the controlled radical polymerization (RAFT). Two main chain polymers containing similar isolated distyrylbenzene (P3) and aromatic 1,3,4‐oxadiazole (P4) chromophores were also synthesized for comparative study. The resulted copolymers (P1–P4) are soluble in common organic solvents and are basically amorphous materials with 5% weight‐loss temperature higher than 360 °C. The PL spectral results reveal that the architecture of P1 prevents the formation of inter‐ or intramolecular interaction. The HOMO and LUMO levels of P2, estimated from cyclic voltammetric data, are −5.96 and −3.81 eV, respectively, which are much lower than those of P1 (−5.12 and −3.11 eV). The emission of blend from P1 and P2 are contributed mainly from distyrylbenzene fluorophore (∼450 nm) owing to efficient energy transfer. Moreover, the blend exhibits three kinds of redox behavior depending on their weight ratios. The luminance and current efficiency of the EL device lpar;ITO/PEDOT/MEH‐PPV+P2/Al) are 503 cd/m2 and 0.11 cd/A, which can be improved to 1285 cd/m2 and 0.44 cd/A, respectively, as the weight ratio of P2 increases from 0 to 20%. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5362–5377, 2006
Cyclic and telechelic ladder polymers derived from tetrahydroxytetramethylspirobisindane and 1,4‐dicyanotetrafluorobenzene
Authors: Kricheldorf Hans R. , Lomadze Nino , Fritsch Detlev , Schwarz Gert
Published: August 2006

5,5′,6,6′‐Tetrahydroxy‐3,3,3′,3′‐tetramethylspirobisindane was polycondensed with 1,4‐dicyanotetrafluorobenzene in four different solvents at 70 °C. In dimethylformamide, N‐methylpyrrolidone, and sulfolane exclusively, cyclic polymers were detectable by matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectrometry up to masses around 13,000 Da. In dimethyl sulfoxide, linear byproducts were also found. Higher temperatures caused degradation reactions catalyzed by potassium carbonate. Polycondensations performed with the addition of 4‐tert‐butyl catechol or 2,2′‐dihydroxy binaphthyl yielded linear telechelic oligomers. Equimolar mixtures of linear and cyclic ladder polymers were examined by MALDI‐TOF mass spectra to determine how the end groups and the cyclic structure influenced the signal‐to‐noise ratio. The results suggested a preferential detection of the linear chains. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5344–5352, 2006
Macrophage Serum‐Based Adhesion to Plasma‐Processed Surface Chemistry is Distinct from That Exhibited by Fibroblasts
Authors: Godek Marisha L. , Malkov Galiya Sh. , Fisher Ellen R. , Grainger David W.
Published: August 2006

Summary: Plasma‐polymerized films deposited from AlAm, HxAm, NVP, NVFA, AA and FC were compared to TCPS and PS surfaces in supporting cellular attachment, viability, and proliferation in serum‐based culture in vitro for extended periods of time (>7 d). Surface patterns were created using multi‐step depositions with physical masks. Cell adhesion in the presence of serum was compared for (monocyte‐) macrophage and fibroblast cell lines. Cellular response was tracked over time, reporting adhesive behavior, proliferative rates, and morphological changes as a function of surface chemistry. Micropatterned surfaces containing different surface chemistries and functional groups (e.g. NH2, COOH, CF3) produced differential cell adhesive patterns for NIH 3T3 fibroblasts compared to J774A.1, RAW 264.7 or IC‐21 (monocyte‐) macrophage cell types. Significantly, macrophage adhesion is substantial on surfaces where fibroblasts do not adhere under identical culture conditions.

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Measurement of Charge Transfer due to Single Particle Impact
Authors: Watanabe Hideo , Samimi Abdolreza , Ding Yu Long , Ghadiri Mojtaba , Matsuyama Tatsushi , Pitt Kendal G.
Published: August 2006

In the processing of particulate solids, interparticle and particle‐wall collisions can generate electrostatic charges. This can lead to a variety of problems ranging from fire and explosion hazards to segregation, caking and blocking. For a fundamental understanding of the particle charging, it is essential to study the charge transfer due to single particle impacts on a target. A new experimental rig that can measure charge generation due to a single impact between a particle and a target plane has been designed and constructed. In this study, pharmaceutical particles were tested by impacting against a stainless steel target. The amount of charge transfer due to impact can be described as a function of impact velocity and impact angle as well as initial charge. It is noted that for a given material, initial particle charge for which no charge transfer occurs, is independent of impact velocity and impact angle.
Measuring Size Distribution of Organic Crystals of Different Shapes Using Different Technologies
Authors: Patchigolla Kumar , Wilkinson Derek , Li Mingzhong
Published: August 2006

The ultrasonic attenuation (UA) technique was developed to measure not only particle size distribution (PSD) but also concentration for on‐line and off‐line analysis of high concentration dispersions. Another significant characteristic along with particle size is particle shape. Particle shape influences the apparent particle size as measured by various instruments. Shape factors have been calculated from microscopic images using conventional image analysis (IA) techniques. Particle sizing data measured by UA is more representative than by IA because much larger samples are used for analysis. In this study UA, laser diffraction (LD) and IA size measurements are compared and the influence of particle shape is investigated.

Data obtained from UA has been combined with information on shape factor from imaging to obtain equivalent particle size distributions. In a previous study [1], the influence of shape on size measurement has been investigated using different sizing techniques for non‐fragile materials. These particles showed significant variation in measured PSD with their different shapes. In this paper, the same phenomenon was observed with evolving polymorphs of L‐glutamic acid crystals (α and β form), oxalic acid, sucrose and monosodium glutamate.
Obtaining Particle Size Distribution from Chord Length Measurements
Authors: Li Mingzhong , Wilkinson Derek , Patchigolla Kumar
Published: August 2006

The Lasentec focused‐beam reflectance measurement (FBRM) is becoming a more popular technique to measure particle size on‐line in different applications. The FBRM uses a focused beam of laser light that scans across particles passing in front of the probe window to measure a chord length distribution (CLD). Compared with CLD information, the particle size distribution (PSD) is more useful because it is directly related to product quality and process productivity. However, it is not straightforward to convert a measured CLD into its corresponding PSD accurately due to the lack of a theoretical analysis for non‐spherical particle systems. In this paper, firstly a general model to translate a PSD into its corresponding CLD is given for different shapes including spherical, ellipsoidal and more general non‐spherical particles. Then an iterative inversion method is developed to obtain the PSD from a measured CLD. Finally, effectiveness of the proposed PSD‐CLD model and iterative inversion method has been extensively validated by experiments.
Particle Size Distribution by Space or Time Dependent Extinction Profiles obtained by Analytical Centrifugation
Authors: Detloff Torsten , Sobisch Titus , Lerche Dietmar
Published: August 2006

The particle size distribution of suspensions of fine particles was determined by a photocentrifuge from transmission/extinction profiles. Photocentrifuges provide a useful tool for the characterization and quality control of suspensions. While the variation of the light extinction curves caused by centrifugal segregation allows a qualitative description, a rigorous formulation provides a quantitative characterization. The present work reports on the determination of the particle size distribution using space and time resolved extinction profiles. The particle size distribution is obtained by analyzing the variation of the extinction at any point of the sample over the full centrifugation time or by analyzing the extinction variation over the entire sample length for any centrifugation time span. The advantage of the second method is the potential to save time.
Development of a Photon Correlation Spectroscopy Instrument to Measure Size Distributions of Nanoparticles
Authors: Yamaguchi Tetsuji , Azuma Yasushi , Okuyama Kikuo
Published: August 2006

This study presents a new method for measuring size distributions of colloidal nanoparticles in a liquid dispersion. This method is based on a photon correlation spectroscopy (PCS) combined with a flow cell and a size exclusion chromatography (SEC). The SEC unit classifies injected nanoparticles into several monodisperse nanoparticles. The classified nanoparticles introduced from the SEC unit are analyzed sequentially by the PCS unit. The size distribution of the polydisperse mixture was calculated by integration of all the monodisperse distributions. The size distributions obtained using the new method were compared with those obtained by scanning electron microscope (SEM) image analysis. For the three kinds of colloidal silica nanoparticles used in this study, good agreement was found, verifying the utility of the methodology.
AFM investigation of the formation of one‐dimensional structures of C60shuttlecocks on HOPG
Authors: Huebener K. , Scheloske M. , Hauschild J. , Harneit W. , Zehl G. , Fiechter S.
Published: August 2006

The formation of one‐dimensional structures of 1,4,11,15,30‐pentakis(biphenyl)‐2‐hydro[60]fullerenes on highly ordered pyrolytic graphite (HOPG) was investigated with an atomic force microscope. These molecules have the shape of a conical shuttlecock with a fullerene at the apex. Topographic images taken in tapping mode showed the formation of round islands, as well as needle shaped structures. The needles arrange in three preferential directions and are only one monolayer high consistent with the formation of molecular chains. Their observed width is compatible with 10 or less molecular rows. By switching into contact mode one can manipulate and disrupt these chains. When switching back into tapping mode, one can observe their regrowth. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis, isolation and characterization of new endohedral fullerenes M@C72 (M = Eu, Sr, Yb)
Authors: Bucher Karin , Epple Lars , Mende Jens , Mehring Michael , Jansen Martin
Published: August 2006

We report on new europium, strontium and ytterbium endohedral fullerene cages of the type Eu@C72, Sr@C72 and Yb@C72. Single isomers of Eu@C72‐I, Sr@C72‐I, Sr@C72‐II and Yb@C72‐I were isolated by multi‐step HPLC for the first time. Details of their synthesis, separation and characterization by LDI‐TOF mass spectrometry and UV‐vis will be discussed. Additionally, EPR spectroscopy of Eu@C72‐I was performed. A second isomer of europium and ytterbium endohedral C72, Eu@C72‐II and Yb@C72‐II, has been separated by HPLC and identified by LDI‐TOF mass spectrometry. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transport and TEM on dysprosium metallofullerene peapods
Authors: Obergfell D. , Meyer J. C. , Haluska M. , Khlobystov A. N. , Yang S. , Fan L. , Liu D. , Roth S.
Published: August 2006

Single‐walled carbon nanotubes (SWNTs) produced by the arc‐discharge method using non‐magnetic catalysts were filled with Dy@C82 endohedral metallofullerenes. Transport measurements were performed on (Dy@C82)@SWNT metallofullerene peapod samples in field‐effect transistor configuration at 4.2 K. After the transport investigations the substrates were partially etched away enabling us to take TEM images of the very same metallofullerene peapod samples on which transport had been carried out before. This procedure gives essential information on whether the sample measured was a single tube or a bundle and on the degree of tube filling. In the case of the presented measurements, TEM investigations revealed one sample to be a metallofullerene peapod bundle and another one to be an individual tube being not or not completely filled despite of a high overall sample filling. Both samples behave as semiconductors, where the latter sample exhibits Coulomb blockade oscillations for low bias voltages. Thus we present the first combined Coulomb blockade diamond and TEM measurements on a single nanotube and moreover the first transport data including the transfer characteristics I sd(V g) of a sample which is confirmed to be a metallofullerene peapod bundle. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Protein splicing In Cis and In Trans
Authors: Saleh Lana , Perler Francine B.
Published: August 2006

Intein‐mediated protein splicing is a self‐catalytic process in which the intervening intein sequence is removed from a precursor protein and the flanking extein segments are ligated with a native peptide bond. Splice junction proximal residues and internal residues within the intein direct these reactions. The identity of these residues varies in each intein, as groups of related residues populate conserved motifs. Although the basics of the four‐step protein splicing pathway are known, mechanistic details are still unknown. Structural and kinetic analyses are beginning to shed some light. Several structures were reported for precursor proteins with mutations in catalytic residues, which stabilize the precursors for crystallographic study. Progress is being made despite limitations inherent in using mutated precursors. However, no uniform mechanism has emerged. Kinetic parameters were determined using conditional trans‐splicing (splicing of split precursor fragments after intein reassembly). Several groups concluded that the rate of the initial acyl rearrangement step is rapid and Asn cyclization (step 3) is slow, suggesting that this latter step is rate limiting. Understanding the protein splicing pathway has allowed scientists to harness inteins for numerous applications. © 2006 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 6: 183–193; 2006: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20082
Structure and function of cis‐prenyl chain elongating enzymes
Authors: Takahashi Seiji , Koyama Tanetoshi
Published: August 2006

All carbon skeletons of isoprenoids, whose chain lengths vary widely from geranyl diphosphate (C10) to natural rubber (C>10,000), are synthesized by sequential condensation of isopentenyl diphosphate with an allylic diphosphate through catalytic functions of a group of enzymes commonly called “prenyltransferases.” Prenyltransferases are classified into two major groups, trans‐ or (E)‐prenyltransferases and cis‐ or (Z)‐prenyltransferases, according to the geometry of the prenyl chain units in the products. From the year 1987, many genes encoding trans‐prenyltransferases were cloned and clearly characterized. In contrast, the structure and detailed mechanism of cis‐prenyltransferase was completely unknown until the identification of a gene encoding the undecaprenyl diphosphate (UPP) synthase from Micrococcus luteus B‐P 26 in 1998. Not only the primary but also the tertiary structure of the UPP synthase is quite different from that of the trans‐prenyltransferases. Multiple alignment of the primary structures of cis‐prenyltransferases identified from various organisms reveals five highly conserved regions. Site‐directed mutagenesis of the conserved amino acid residues in UPP synthases based on the crystal structure has elucidated the basic catalytic mechanisms. Moreover, comparison of the structures of short‐, medium‐, and long‐chain cis‐prenyltransferases reveals important amino acid residues for product chain length determination, which enabled us to understand the regulation mechanism of the ultimate chain length among cis‐prenyltransferases. © 2006 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 6: 194–205; 2006: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20083
Total syntheses of polyketide‐derived bioactive natural products
Authors: Tatsuta Kuniaki , Hosokawa Seijiro
Published: August 2006

Recent progress of total syntheses in our laboratory has been described along with our background and methodologies. The target bioactive polyketides are classified into three categories according to their structures: (i) lactone‐fused polycyclic compounds [(+)‐cochleamycin A, (+)‐tubelactomicin A, and (−)‐tetrodecamycin], (ii) aromatic compounds [(−)‐tetracycline, (−)‐BE‐54238B, lymphostin, and (−)‐lagunamycin], and (iii) acyclic polyketides [xanthocillin X dimethylether, (+)‐trichostatin D, and (+)‐actinopyrone A]. Features of the total syntheses are described. Original methodologies have been developed and applied to construct the inherent structures of the target molecules. Most syntheses cited herein are the first total syntheses, and the absolute structures of the target molecules have been determined. © 2006 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 6: 217–233; 2006: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20084
Inorganic functional materials: optimization of properties by structural and compositional control
Authors: West Anthony R.
Published: August 2006

A review is given of the strategies used to dope inorganic solids and the consequences for properties such as ionic and electronic conductivity. Doping mechanisms involve either substitution of foreign ions onto lattice sites, creation of vacancies on either cation or anion sites, or population of normally empty interstitial sites by either anions or cations. Mechanisms for charge compensation associated with aliovalent doping are reviewed and examples are given in the fields of solid state ionics and high‐temperature superconductivity. The strategies used for targeting materials with new properties are reviewed, including a surprising number of cases where startling new properties are encountered in well‐known materials. Specific examples discussed include MgB2superconductor, Na β‐alumina sodium ion conductor, Ca12Al14O33oxide ion conductor, LiCoMnO4lithium battery cathode, doped Li4SiO4tunable lithium ion conductor, and La‐doped BaTiO3ferroelectric, which can be either semiconducting or insulating. Examples are also given of a curious observation that extraordinary properties are often encountered in materials that are on the edge of stability, either structurally or compositionally or at the crossover between different property types. © 2006 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 6: 206–216; 2006: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20086
Aging-related temporal constraints to stability and instability in postural control
Authors: Slobounov Semyon M. , Haibach Pamela S. , Newell Karl M.
Published: August 2006

In this study, we review the evidence that older adults tend to have both a shorter time to lose stability in the maintenance of standing posture and the functionally related but inverse problem of needing more time to reacquire stability in transitioning to a postural state. These age-related time limitations to processes of stability are hypothesized to enhance the probability of falling with aging and the problems that can occur in the transition between activities, such as sitting to standing and standing to walking. The potential role of fitness and health variables in mediating the temporal constraints on the acquisition and loss of postural stability in aging is discussed.
Nuclear bile acid receptor FXR as pharmacological target: Are we there yet?
Authors: Modica Salvatore , Moschetta Antonio
Published: August 2006

The farnesoid X receptor (FXR) is a member of the nuclear receptor superfamily that is primarily expressed in the enterohepatic system where it functions as intracellular sensor for bile acids. Ligand dependent FXR activation induces transcriptional responses to coordinately regulate bile acid, cholesterol, triglyceride and glucose metabolism, and to protect the intestinal mucosa from bacterial overgrowth and inflammatory insults. Here we discuss the latest discoveries in FXR‐driven metabolic pathways with relevance to pathophysiology and novel therapeutic approaches of several conditions such as hypertriglyceridemia, type 2 diabetes, cholesterol gallstone disease, steato‐hepatitis and metabolic syndrome.
Activation of the Escherichia coli cell division protein FtsZ by a low‐affinity interaction with monovalent cations
Authors: Tadros Michael , González José Manuel , Rivas Germán , Vicente Miguel , Mingorance Jesús
Published: August 2006

We have investigated the activation of FtsZ by monovalent cations. FtsZ polymerization was dependent on the concentrations of protein and monovalent salts, and was accompanied by the uptake of a single ion per monomer added. The affinity and the specificity for the cation were low. Potassium, ammonium, rubidium or sodium activated FtsZ to different extents. Electron microscopy showed that polymers formed with either rubidium, or potassium, were very similar, as were their nucleotide turnover rates. The GTPase activity was lower with rubidium than with potassium, indicating that nucleotide exchange is independent of nucleotide hydrolysis. Control of polymerization by binding of a low affinity cation might govern the dynamic behavior of the FtsZ polymers.
Bradykinin activates ADP‐ribosyl cyclase in neuroblastoma cells: Intracellular concentration decrease in NAD and increase in cyclic ADP‐ribose
Authors: Higashida Haruhiro , Salmina Alla , Hashii Minako , Yokoyama Shigeru , Zhang Jia-Sheng , Noda Mami , Zhong Zen-Guo , Jin Duo
Published: August 2006

ADP‐ribosyl cyclase activity in the crude membrane fraction of neuroblastoma × glioma NGPM1‐27 hybrid cells was measured by monitoring [3H] cyclic ADP‐ribose (cADPR) formation from [3H] NAD+. Bradykinin (BK) at 100 nM increased ADP‐ribosyl cyclase activity by about 2.5‐fold. Application of 300 nM BK to living NGPM1‐27 cells decreased NAD+ to 78% of the prestimulation level at 30 s. In contrast, intracellular cADPR concentrations were increased by 2–3‐fold during the period from 30 to 120 s after the same treatment. Our results suggest that cADPR is one of the second messengers downstream of B2 BK receptors.
Optimal stability of a redundant mobile manipulator via genetic algorithm
Authors: Meghdari Ali , Naderi Davood , Eslami Sohrab
Published: August 2006

Once the path of the vehicle and the desired task of the end-effector are predefined, in order to apply the optimal stability criterion, the manipulator should be redundant. In this paper, the goal is to find the position, angular velocity, and angular acceleration of the redundant link of the manipulator such that the entire system becomes optimally stable. By considering the full dynamic interaction between the manipulator and its vehicle, the stability issue becomes more complex. There are some measures of stability and one of them is the tire's upward force. This measure tries to equalize the upward forces of the tires that lead to optimal stability and better steer-ability. Optimizing the parameters of various engineering problems is a challenging issue. In this research, the optimal position, angular velocity, and angular acceleration of the redundant link are found by the genetic algorithm approach such that the upward forces of vehicle tires are nearly equal. Furthermore, the effectiveness of this procedure is shown by presenting an example.
Cell Detachment Model for an Antibody‐Based Microfluidic Cancer Screening System
Authors: Wankhede Swapnil P. , Du Zhiqiang , Berg Jordan M. , Vaughn Mark W. , Dallas Tim , Cheng Kwan H. , Gollahon Lauren
Published: August 2006

We consider cells bound to the floor of a microfluidic channel and present a model of their flow‐induced detachment. We approximate hydrodynamic force and cell elastic response using static finite‐element simulation of a single cell. Detachment is assumed to occur when hydrodynamic and adhesive forces are roughly equal. The result is extended to multiple cells at the device level using a sigmoidal curve fit. The model is applied to a microfluidic cancer‐screening device that discriminates between normal epithelial cells and cells infected with human papillomavirus (HPV), on the basis of increased expression of the transmembrane protein α6 integrin in the latter. Here, the cells to be tested are bound to a microchannel floor coated with anti α6 integrin antibodies. In an appropriate flow rate range, normal cells are washed away while HPV‐infected cells remain bound. The model allows interpolation between data points to choose the optimal flow rate and provides insight into interaction of cell mechanical properties and the flow‐induced detachment mechanism. Notably, the results suggest a significant influence of cell elastic response on detachment.
GPS zenith delay sensitivity evaluated from high‐resolution numerical weather prediction simulations of the 8–9 September 2002 flash flood over southeastern France
Authors: Brenot Hugues , Ducrocq Véronique , Walpersdorf Andrea , Champollion Cédric , Caumont Olivier
Published: August 2006

Estimations of zenith total delays (ZTD) were obtained during postprocessing of a high‐resolution (2.4 km) nonhydrostatic atmospheric model (Méso‐NH). These estimations were used to determine their sensitivity with respect to formulations of atmospheric refractivity, the approximation of zenith hydrostatic delays (ZHD) deduced from ground pressure, and the contributions of hydrometeors. The factor κ for the conversion of zenith wet delay (ZWD) to integrated water vapor (IWV) was examined. Méso‐NH is applied here to the extreme flash flood event of 8–9 September 2002 in southeastern France. The use of the hydrostatic formulation (to infer ZHD) leads to an overestimation of up to 18 mm with respect to the vertical integration of refractivity. Delay contributions of hydrometeors simulated by the high‐resolution model reached more than 70 mm (≈11 kg/m2 IWV) in the heart of the convective cells in the case of the extreme flood event. The mean variations of IWV due to the use of different conversion factors (κ used to transform ZWD to IWV) are evaluated to be less than 0.3 kg/m2. This is less than the mean underestimation of IWV by 0.6 kg/m2 relative to the GPS‐like evaluation of IWV using the hydrostatic formulation and the ground temperature. In this study we also use GPS ZTD observations to validate three different numerical simulations of this extreme flood event. The simulation with the best fit to the GPS observations is also in best agreement with the surface rainfall measurements.
Sulfate source inventories from a Svalbard ice core record spanning the Industrial Revolution
Authors: Moore John , Kekonen Teija , Grinsted Aslak , Isaksson Elisabeth
Published: August 2006

The 800‐year sulfate record from Lomonosovfonna was analyzed by a novel multiple linear regression algorithm that attempts to explain sulfate variability in terms of other chemical species measured in the core and sulfur emission inventories. We use three statistical approaches to determine sulfate sources. We examine trends using singular spectrum analysis with confidence intervals, finding clear evidence that anthropogenic sources are important but not dominant; we use cross‐wavelet coherence to examine significant multidecadal covariance in terrestrial sulfate; but our main tool is multiple regression analysis of the sulfate dependency on other ions and anthropogenic emission inventories. Models are fitted in a moving time window of typically 50 years length, explaining 80% of the sulfate variance. A suite of model predictors are examined, and the variation in relative magnitudes of the model coefficients along the core can be used to infer variations in the strength of various sulfate sources. We observe large changes in sulfate sources at the end of the Little Ice Age associated with changes in Barents Sea marine productivity, changes in North Atlantic sulfate input and a long‐lasting period of disturbance caused by the large Laki volcanic eruption. Modeling sulfur emission inventories shows that western Europe contributes about 15% of the sulfate budget, with essentially no input from other regions, in contrast with predictions from global circulation models incorporating sulfur chemistry. Multidecadal cycles are mainly confined to the Little Ice Age and most likely associated with increased storminess and enhanced deposition of both marine aerosol and biogenic sulfate from the Atlantic Ocean. The model residuals do not show a normal distribution but display very large spikes. Unexpectedly, those significant at the 99% level can be closely matched to major volcanic eruptions using independent dating methods. The 20th century sulfate in the core is inventoried as sea salt (15%), terrestrial (10%), volcanic (5–10%), western European anthropogenic (10–25%), Barents Sea biogenic (20–40%), and Atlantic biogenic (10–15%).
Seasonal exchange of CO2 and δ18O‐CO2 varies with postfire succession in boreal forest ecosystems
Authors: Welp L. R. , Randerson J. T. , Liu H. P.
Published: August 2006

Seasonal cycles of atmospheric CO2 and δ18O‐CO2 at high northern latitudes have the potential to serve as indicators of ecological change in response to climate changes. Effective interpretation of these observations requires an understanding of how different species and ecosystems contribute to biosphere‐atmosphere exchange. Here we examined the effect of postfire stand age in boreal forest ecosystems on the seasonal distribution of CO2 and δ18O‐CO2 fluxes. We measured net CO2 fluxes in a 3‐year burn scar, a 15‐year trembling aspen stand, and an 80‐year black spruce stand in interior Alaska using eddy covariance. By combining measurements of the oxygen isotopic composition of ecosystem water pools at each stand with measured CO2 fluxes, we predicted half‐hourly δ18O‐CO2 fluxes and used a one‐box atmosphere model to make relative comparisons of the effect of stand age on the shape and amplitude of the seasonal cycle of CO2 and δ18O‐CO2. A shorter growing season and higher rates of net ecosystem uptake during midsummer at the 15‐year stand resulted in a larger seasonal CO2 amplitude and a delay in the drawdown of atmospheric CO2 as compared with the 80‐year stand. Reduced levels of gross primary production isoforcing from the 15‐year stand during spring and early summer caused atmospheric δ18O‐CO2 to increase more gradually between April and June as compared with fluxes from the 80‐year stand. Our analysis suggests that increased boreal forest disturbance would delay the phase of CO2 drawdown at high northern latitudes, but would advance the phase of δ18O‐CO2 drawdown.
Transient effects of groundwater pumping and surface‐water‐irrigation returns on streamflow
Authors: Kendy Eloise , Bredehoeft John D.
Published: August 2006

In surface‐water‐irrigated western valleys, groundwater discharge from excess irrigation sustains winter streamflow at levels that exceed natural flows. This unnatural condition has persisted for so long that hydrologists, water managers, and water users consider it to be normal. Changing land uses and irrigation practices complicate efforts to manage groundwater discharge and, in turn, to protect instream flows. We examined the impacts on streamflow of (1) seasonal groundwater pumping at various distances from the Gallatin River and (2) improving irrigation efficiency in the Gallatin Valley, Montana. We show that the greater the distance from a seasonally pumping well to a stream, the less the stream depletion fluctuates seasonally and the greater the proportion of annual depletion occurs during the nonirrigation season. Furthermore, we show that increasing irrigation efficiency has implications beyond simply reducing diversions. Improving irrigation efficiency reduces fall and winter flows to a lower, but more natural condition than the artificially high conditions to which we have become accustomed. However, existing water users and aquatic ecosystems may rely upon return flows from inefficient irrigation systems. By strategically timing and locating artificial recharge within a basin, groundwater and surface water may be managed conjunctively to help maintain desirable streamflow conditions as land uses and irrigation practices change.
Monitoring of an infiltration experiment using the self‐potential method
Authors: Suski B. , Revil A. , Titov K. , Konosavsky P. , Voltz M. , Dagès C. , Huttel O.
Published: August 2006

An infiltration test was performed from a ditch with the purpose of monitoring the evolution of the piezometric levels using self‐potential measurements made at the ground surface. We used a set of 18 piezometers and a network of 41 nonpolarizable (Pb/PbCl2) electrodes. The variations of the self‐potential signals are linearly correlated to the piezometric level changes with an apparent voltage coupling coefficient of −5.5 ± 0.9 mV m−1. We measured, independently of this infiltration test, the three material properties entering the macroscopic field equations. They are the resistivity distribution of the soil, its mean hydraulic conductivity, and its intrinsic streaming potential coupling coefficient (−5.8 ± 1.1 mV m−1). Then, we modeled numerically the infiltration test and the associated self‐potential signals using a two‐dimensional finite difference code. The numerical model reproduces fairly well the observed results. This investigation demonstrates the effectiveness of the self‐potential method in field conditions to monitor small variations (<0.60 m) of the water table. It offers for the first time a test of the electrokinetic theory in the field with independent evaluation of the material properties entering the field equations.
Laboratory measurements of P‐ and S‐wave velocities in polycrystalline plagioclase and gabbronorite up to 700 °C and 1 GPa: Implications for the low velocity anomaly in the lower crust
Authors: Kono Yoshio , Ishikawa Masahiro , Arima Makoto
Published: August 2006

P‐ (Vp) and S‐wave (Vs) velocities of polycrystalline plagioclase (An51±1) and gabbronorite including plagioclase (An49±2) (62.3vol.%) were measured up to 700°C at 0.6, 0.8, and 1.0GPa during heating and cooling. Both polycrystalline plagioclase and gabbronorite show reversible and discontinuous change in temperature derivative of Vp and Vs, ∂Vp/∂T and ∂Vs/∂T, respectively, at about 400°C. The ∂Vp/∂T and ∂Vs/∂T of the polycrystalline plagioclase changes from −0.8 × 10−4 to −3.4 × 10−4 km s−1°C−1 and from −1.1 × 10−4 to −3.3 × 10−4 km s−1°C−1, respectively. The ∂Vp/∂T and ∂Vs/∂T of the gabbronorite varies from −1.0 × 10−4 to −3.4 × 10−4 km s−1°C−1 and from −0.4 × 10−4 to −3.5 × 10−4 km s−1°C−1, respectively. The reversible and discontinuous changes in ∂Vp/∂T and ∂Vs/∂T are attributed to a phase transformation of plagioclase. The present data suggest that the sharp decrease in Vp and Vs would cause low velocity anomaly under dry and subsolidus melt‐absent conditions in the mid‐to‐lower crust of relatively high heat flow regions.