bluuebunny/crossref_metadata_2025 huggingface dataset:
Peroxide crosslinking of a styrene‐free unsaturated polyester
Authors: Mironi‐Harpaz I. , Narkis M. , Siegmann A.
Published: April 2007

Thermoset unsaturated polyesters are usually obtained by the crosslinking of unsaturated polyester chains dissolved in an unsaturated, reactive, monomeric diluent, which is usually styrene. This article describes a new approach in which styrene‐free unsaturated polyester chains are intrinsically cured into a crosslinked matrix. The gel time, gel content, swelling degree, glass‐transition temperature, dynamic mechanical properties, tensile properties, and molecular weight between crosslinks (calculated according to both the Flory–Rehner equation and the theory of rubber elasticity) of the crosslinked polymer are studied as a function of the peroxide concentration. All properties change considerably upon the addition of small amounts of peroxide (between 1 and 2 wt %) and change to a lesser extent with higher peroxide concentrations (up to 6 wt %). The thermal properties of the isolated gel fraction are studied as a function of the peroxide concentration. The sol fraction demonstrates a plasticizing effect on the crosslinked network, affecting the glass‐transition temperature and stress–strain behavior of the crosslinked polymer. In light of the crosslink densities derived from swelling experiments, a molecular structure and crosslinking mechanism are suggested for the gel fractions of 1 and 6 wt % peroxide crosslinked unsaturated polyester chains. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Investigation of MWNTs/PBO nanocomposite polymerization mechanism with model compound
Authors: Li Xia , Huang Yudong , Cao Hailin , Liu Li
Published: April 2007

A model compound was obtained by reaction of benzoic acid and 4,6‐diamino‐1,3‐dihydroxybenzene dihydrochloride (DADHB · 2HCl) in the presence of functionalized multiwall carbon nanotubes (FMWNTs). FMWNTs were formed on raw multiwall carbon nanotubes (MWNTs) by chemical modification. The model compound was rinsed by chloroform and MWNTs were separated by centrifuge. The sediment yielded was denoted as graft multiwall carbon nanotubes (GMWNTs). Then X‐ray photoelectron spectroscopy (XPS), Raman spectroscopy, and Fourier‐transform infrared (FTIR) were used to investigate the existence of covalent bond between DADHB and FMWNTs. The results of XPS showed that nitrogen atoms amounted to about 3.3% except for oxygen and carbon on the surface of GMWNTs. Meantime, the reaction of COOH of the FMWNTs and themonomer DADHB occurred, and benzoxazole was formed predominantly by Raman spectroscopy analysis. FTIR spectroscopy confirmed the covalent grafting of monomer to FMWNTs in the processing procedure. As a result, the mechanism of the reaction of the poly(p‐phenylenebenzoxazole) (PBO) oligomer and FMWNT composites was deduced according to the reaction of the model compound. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Novel Gd‐substituted LiNi ferrite/polyaniline composite prepared by in situ polymerization
Authors: Jiang Jing , Li Liangchao , Xu Feng
Published: April 2007

Magnetic composite containing polyaniline (PANI)‐coated LiNi0.5Gd0.08Fe1.92O4 was synthesized by in situ polymerization of aniline on the surface of LiNi0.5Gd0.08Fe1.92O4 ferrite particles. The obtained samples were characterized by powder X‐ray diffraction, Fourier transform infrared spectra, UV–visible absorption spectra, thermogravimetric analysis, transmission electron microscopy (TEM), and vibrating sample magnetometer. The results of spectroanalysis indicated that there was interaction between PANI chains and ferrite particles. TEM study showed that composite presented the core–shell structure. The composite under applied magnetic field exhibited the clear hysteretic behavior at room temperature. The bonding mechanism in the composite had been discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Preparation and characterization of poly(D,L‐lactic‐co‐glycolic acid) nanoparticles containing 3‐(benzoxazol‐2‐yl)‐7‐(N,N‐diethyl amino)chromen‐2‐one
Authors: Gomes Anderson J. , Assunção Rosana Maria Nascimento , Filho Guimes Rodrigues , Espreafico Enilza M. , Machado Antonio Eduardo da Hora
Published: April 2007

Nanoparticles (NPs) of poly(D,L‐lactic‐co‐glycolic acid) containing the compound 3‐(benzoxazol‐2‐yl)‐7‐(N,N‐diethyl amino)chromen‐2‐one (C2) were prepared by the solvent‐evaporation technique with a mean loading efficiency of 74.0 ± 3.0%. Size distribution studies, done with dynamic light scattering and scanning electron microscopy, revealed that these particles were spherical in shape, with a mean diameter of 253 nm, a low polydispersity, and a tendency toward aggregation; the last was confirmed by the low ζ potential. A low release profile was observed for C2 when the NPs were dispersed in Hank's buffer (pH = 7.4); this was related to the low porosity of the NPs and the extremely low diffusivity of C2 in water. Differential scanning calorimetry data presented a glass‐transition temperature depression caused by an increase in the NP molecular mobility after the incorporation of C2. Spectroscopic and photophysical data exploring the capabilities of C2 as a fluorescent probe suggested a high microviscosity for the environment in which the probe was allocated, which was most likely due to strong polar interactions involving ester groups from the polymer and the diethylamino moiety from C2. The cellular toxicity and uptake of C2 and NP–C2 systems were evaluated with B16‐F10 murine cells, which showed that C2 (in solution or encapsulated) was nontoxic and able to be located inside the neoplasic cells. Besides, the encapsulation method was capable of maintaining the drug's properties and improved the drug delivery to the target cell. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
High resolution NMR study of tropical fruit seed starches
Authors: de Miranda Costa Paula , Bruno Tavares Maria Inês , Bathista André L. B. S. , da Silva Emerson O. , Nogueira José S.
Published: April 2007

The nuclear magnetic resonance spectroscopy (NMR) studies of starches obtained by fruit seeds such as melon and watermelon were carried out as an analytical methodology to understand the molecular dynamic behavior. This study was also accompanied by the conventional X‐ray diffraction and thermal analysis. The NMR results give us a complete behavior of the samples at the molecular level. Thus, the information obtained from NMR will complement the data obtained from X‐ray and thermal analysis allowing us having responses on samples structure and dynamical behavior. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Thermal and mechanical properties of polystyrene/poly(acrylonitrile‐g‐(ethylene‐co‐propylene‐co‐diene)‐g‐styrene) (AES) blends prepared by the in situ polymerization of styrene
Authors: Lourenço Emerson , Felisberti Maria Isabel
Published: April 2007

Polystyrene/AES blends formed by the in situ polymerization of styrene in the presence of poly(acrylonitrile‐g‐(ethylene‐co‐propylene‐co‐diene)‐g‐styrene) (AES) were prepared. AES is a commercial elastomer obtained by the radical copolymerization of styrene and acrylonitrile in the presence of an ethylene–propylene–diene terpolymer (EPDM). The polystyrene/AES blends presented two phases: an EPDM elastomeric phase dispersed in a rigid matrix. The phase behavior was strongly affected by the polymerization temperature. The blends showed higher thermal stability than the polystyrene homopolymer because of the stabilizing effect of EPDM incorporation. The mechanical properties were influenced by the polymerization temperature and blend composition. The blend prepared at 60°C with 13.0 wt % AES presented an enhancement of 60% in the impact resistance, whereas the blend prepared at 80°C with 21.8 wt % AES presented an enhancement of 150% in the strain at break. Both blends had these properties improved with a small loss in the Young's modulus. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Classifying community colleges: How rural community colleges fit
Authors: Hardy David E. , Katsinas Stephen G.
Published: April 2007

This chapter describes rural community colleges, compares them to their urban and suburban counter‐parts, and highlights the unique challenges they face in the twenty‐first century.
Recruiting and retaining rural community college faculty
Authors: Murray John P.
Published: April 2007

Much is being written about a potential shortage of qualified community college faculty. Rural community colleges may be at the greatest disadvantage in attracting and retaining new faculty because they cannot offer the financial, cultural, and social advantages that more urban institutions can. This chapter describes the factors rural community college leaders must consider when recruiting and hiring new professors.
Faculty development in rural community colleges
Authors: Eddy Pamela L.
Published: April 2007

This chapter describes results from a national study of community college faculty development programs. Findings highlight how the challenges faced by rural colleges differ from those at urban institutions, which often have dedicated faculty development centers.
Connecting to the larger world: Distance education in rural community colleges
Authors: Cejda Brent D.
Published: April 2007

This chapter reviews the literature on the status of distance education in rural community colleges, and addresses issues rural community colleges face in implementing distance education.
Expression of Concern: Mechanisms of synthetic serine protease inhibitor (FUT‐175)‐mediated cell death
Authors: Uwagawa Tadashi , Li Zhongkui , Chang Zhe , Xia Qianghua , Peng Bailu , Sclabas Guido M. , Ishiyama Satoshi , Hung Mien‐Chie , Evans Douglas B. , Abbruzzese James L. , Chiao Paul J.
Published: April 2007

BACKGROUND

Constitutive activation of nuclear factor‐κB (NF‐κB) is a frequent molecular alteration in pancreatic cancer and a number of studies have suggested that constitutive NF‐κB activity plays a key role in the aggressive behavior of this disease. In an attempt to identify an effective therapeutic agent for pancreatic cancer, the authors studied the role of FUT‐175, a synthetic serine protease inhibitor, in the inhibition of NF‐κB activation and the induction of apoptotic responses.

METHODS

To examine the effect of FUT‐175 on the inhibition of NF‐κB and the induction of apoptosis in pancreatic cancer cell lines, Western and Northern blot analyses, electromobility shift (EMSA), luciferase reporter gene, DNA fragmentation, immunoprecipitation, in vitro kinase, small interfering RNA (siRNA), and chromatin immunoprecipitation (ChIP) assays were performed.

RESULTS

In a time‐dependent and dose‐dependent manner, FUT‐175 inhibited IκBα phosphorylation and NF‐κB activation, thereby inhibiting the antiapoptotic activity of NF‐κB. Simultaneously, FUT‐175 up‐regulated the expression of tumor necrosis factor receptor‐1 (TNFR1), which in turn activated the proapoptotic caspase‐8 and Bid pathways and induced apoptosis in pancreatic cancer cells. FUT‐175‐induced activation of Fas‐associated death domain (FADD) and caspase‐8 was suppressed by RNA interference‐mediated inhibition of TNFR1 expression. Furthermore, expression of the transcription factor PEA3 was up‐regulated by FUT‐175 and was involved in FUT‐175–mediated TNFR1 expression.

CONCLUSIONS

These results suggested a possible mechanism by which FUT‐175 may disrupt interconnected signaling pathways by both suppressing the NF‐κB antiapoptotic activity and inducing TNFR‐mediated apoptosis. Supported by this unique function as a NF‐κB inhibitor and apoptosis inducer, this well‐established synthetic serine protease inhibitor with as‐of‐yet poorly understood mechanisms of actions appears to be a potentially therapeutic agent for pancreatic cancer. Cancer 2007. © 2007 American Cancer Society.
Growth and characterization of a novel organic NLO crystal: 4 – ethoxy benzaldehyde – n – methyl 4 – stilbazolium tosylate
Authors: Jagannathan K. , Kalainathan S. , Gnanasekaran T. , Vijayan N. , Bhagavannarayana G.
Published: April 2007

The organic material 4‐Ethoxybenzaldehyde‐N‐methyl 4‐Stilbazolium Tosylate (EBST) is a new NLO material and new derivative in Stilbazolium Tosylate family. In this work we synthesized the EBST, the derivative of DAST. By slow evaporation method, we have grown the EBST crystal. Powder XRD confirms the crystalline property, the lattice parameters are calculated from single crystal XRD data and the molecular structure also revealed. The crystal system is found as monoclinic. The crystalline perfection is assessed by the high‐resolution X‐ray diffractometry. A single and reasonably sharp peak observed in the diffraction curve indicates that the quality of the crystal is quite good without having any internal structural grain boundaries. The FTIR and proton NMR study confirm the presence of functional groups. From the UV – Vis Far IR absorption spectra the good transparency is revealed. The Kurtz Perry SHG test confirms the NLO property of the EBST crystal grown and it is 11 times greater than urea. The melting point of the grown crystal is found to be 237°C from the DSC curve. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structure and optical damage resistance of In:Yb:Er:LiNbO3 crystals
Authors: Hu Zhenghua , Guo Peng , Li Jingying , Zhen Xihe
Published: April 2007

A series of In:Yb:Er:LiNbO3 crystals have been grown. The UV‐Vis absorption spectra and Infrared (IR) transmission spectra were measured and discussed in terms of the spectroscopic characterizations and the defect structure of the In:Yb:Er:LiNbO3 crystals. The optical damage resistance was characterized by the transmitted beam pattern distortion method. The optical damage resistance of In (3.0mol %):Yb:Er:LiNbO3 crystal is one order of magnitude higher than that of other crystal. The dependence of the optical damage resistance on the defect structure was studied. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Role of oxygen vacancies in the coloration of 0.65Pb(Mg1/3Nb2/3)O3‐0.35PbTiO3 single crystals
Authors: Xia Zhiguo , Li Qiang , Cheng Ming
Published: April 2007

The coloration and oxygen vacancies in 0.65Pb(Mg1/3Nb2/3)O3‐0.35PbTiO3 (PMN‐PT(65/35)) (starting composition) single crystals grown by a so‐called modified Bridgman technique were investigated in this paper. Light yellow and dark brown colored crystals were generally observed for the typical as‐grown PMN‐PT(65/35) single crystals. X‐ray diffraction results demonstrated that they were both of pure perovskite structure, but good electric properties were only obtained for the light yellow crystal. X‐ray photoelectron spectroscopy (XPS) was used to investigate the electronic structure of its components. The O 1s photoelectron spectra of the dark brown colored crystals located at the higher binding energy side, which meant the existence of the more oxygen vacancies. It accordingly led to the formation of the low valence cations associated with the coloration of the crystals, which is also testified by the obtained X‐ray photoelectron spectra of Ti and Nb. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quasi Exact Model for the Anisotropy Driven Weibel Instability all over Fourier Space
Authors: Bret A.
Published: April 2007

The Weibel instability is prompted by a temperature anisotropy within a plasma. We investigate its growth rate for wave vectors making an arbitrary angle with the high temperature axis. We use a two temperatures waterbags model and derive stability conditions depending on both temperatures and wave vector orientation. It is found that the growth rate is maximum for wave vectors normal to the high temperature axis. Also, a critical angle is evidenced in the k space in which direction modes are unstable at high k although the growth rate decreases quickly in this direction. Exact results are derived in most cases. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dispersion of Dust Acoustic Modes and Perturbations of Plasma Flux Balance
Authors: Tsytovich V. , Morfill G.
Published: April 2007

Previous considerations of dust acoustic waves is demonstrated to be inconsistent ‐ the required equilibrium state for perturbations was not defined since balance of plasma fluxes was neglecting. The self‐consistent treatment shows that plasma flux perturbations are accompanying any collective waves propagating in dusty plasmas and can play an important role in wave dispersion, wave damping and can create instabilities. This is illustrated by the derivation of dispersion relation for dust acoustic modes taking into account the plasma flux balances and plasma flux perturbations by waves. The result of this approach shows that the dust acoustic waves with linear dependence of wave frequency on the wave number exist only in restricted range of the wave numbers. Only for wave numbers larger than some critical wave number for low frequency modes the frequency can be have approximately a linear dependence on wave number and can be called as dust acoustic wave but the phase velocity of these waves is different from that which can be obtained neglecting the flux balance and depends on grain charge variations which are determined by the balance of fluxes. The presence of plasma fluxes previously neglected is the main typical feature of dusty plasmas. The dispersion relation in the range of small wave numbers is found to be mainly determined by the change of the plasma fluxes and is quite different from that of dust acoustic type, namely it is found to have the same form as the well known dispersion relation for the gravitational instability. This result proves in general way the existence of the collective grain attractions of negatively charged grains for for large distances between them and for any source of ionization. The attraction of grains found from dispersion relation of the dust acoustic branch coincides with that found previously for pair grain interactions using some models for the ionization source. For the existing experiments the effective Jeans length for such attraction is estimated to be about 8 – 10 times larger than the ion Debye length and the effective gravitational constant for the grain attraction is estimated to be several orders of magnitude larger than the usual gravitational constant. The grain attraction at large inter‐grain distances described by the gravitationlike grain instability is considered as the simplest explanation for observed dust cloud clustering, formation of dust structures including the plasma crystals. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Tungsten‐Doped Vanadium Oxides Prepared by Direct Liquid Injection MOCVD
Authors: Vernardou D. , Pemble M. E. , Sheel D. W.
Published: April 2007

This paper examines the effect of doping on vanadium(IV) oxide (VO2 (M)) coatings on glass, using atmospheric‐pressure, direct liquid injection metal‐organic (DLI‐MO)CVD, which potentially may find application as part of smart glazing units. It is found that tungsten‐doped VO2 (M) deposited on commercial SiO2‐precoated glass using a 0.1 M solution of vanadyl(IV) acetylacetonate (VO(acac)2) and tungsten (VI) ethoxide (W(OC2H5)5) in methanol shows a reduction in thermochromic transition temperature (Tc) from 60 °C in VO2 (M) to 35 °C in V0.98W0.02O2. This finding is discussed in terms of various atomic percentages of tungsten and oxygen flow rates. The crystallinity, composition, morphology, optical properties, uniformity, and oxidation phase of the films are evaluated by X‐ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), scanning electron microscopy (SEM), IR reflectance‐transmittance, and Raman spectroscopy, respectively. The relationship between dopant concentration and Tc in the most applicable range for solar window coatings is refined by formation of a single‐phase film and precise determination of these parameters.
Radical Enhanced Atomic Layer Deposition of Titanium Dioxide
Authors: Niskanen A. , Arstila K. , Leskelä M. , Ritala M.
Published: April 2007

Titanium dioxide films are grown with radical‐enhanced atomic layer deposition (RE‐ALD) from titanium isopropoxide and oxygen radicals at between 50 and 300 °C on silicon, glass, platinum, and RuO2 surfaces. Additionally, the films are grown on polymers and natural fibers at 50 °C. The oxygen radicals are produced by dissociating molecular oxygen with a remote microwave plasma discharge. Purified argon is used as the carrier and purge gas. Growth rate saturation and conformal growth are observed, and thus the film growth in the ALD mode was proven. The saturated growth rate is 0.19 nm per cycle at 50 °C, with an overall cycle time of 11 s. The film grown at 50 °C has a dielectric constant of 20, and undergoes catastrophic breakdown at 0.6 MV cm–1 electric field. It contains 13 at.‐% hydrogen and 4 at.‐% carbon. As the deposition temperature is increased to 250 °C, the impurity contents decrease to 0.5 at.‐% for hydrogen and 0.4 at.‐% for carbon. The film density and refractive index are 3.2 g cm–3 and 2.2, respectively, for a film deposited at 50 °C, and increases to 3.8 g cm–3 and 2.4, respectively, for a film deposited at 250 °C. All the films grown below 250 °C are amorphous according to X‐ray diffraction (XRD).
Focused Electron Beam Induced Deposition of Si‐Based Materials From SiOxCy to Stoichiometric SiO2: Chemical Compositions, Chemical‐Etch Rates, and Deep Ultraviolet Optical Transmissions
Authors: Perentes A. , Hoffmann P.
Published: April 2007

Room temperature focused electron beam (FEB) induced deposition of contamination‐free transparent materials is a major issue for the FEB production of nano‐optical structures, microchip editing (insulating and passivation layers), and photolithography mask repair. In this work, stoichiometric SiO2 is successfully deposited from three different organosilanes: tetraethoxysilane (TEOS, Si(OCH2CH3)4), tetramethoxysilane (TMOS, Si(OCH3)4), and tetramethylsilane (TMS, Si(CH3)4). The FEB depositions are assisted by a molecular oxygen flux injected simultaneously with the precursor gas. The dependencies on the additional oxygen flux of the chemical compositions of the resulting deposits are studied in detail. Threshold [O2]:[precursor] molecular flux ratios, above which carbon is no longer detectable in the deposited material, are 1.75, 0.15, and 0.05, for TEOS, TMOS, and TMS, respectively. Contamination side‐reactions such as oxygen incorporation in the deposited material due to residual gases in the scanning electron microscope (SEM) chamber are shown to be significant at standard high‐vacuum operating pressures of 5 × 10–5 mbar. The quality of deposited SiO2 obtained from the three precursors is estimated by exposing the material to standard industry cleaning procedures. The etching tests indicate that TMS leads to denser deposits than the two other silanes. The optical transmissions of the deposited SiO2 obtained from TMOS and TMS are measured at 193 nm wavelength, and are 80 % and 99 %, respectively. The latter value fulfills the photomask repair requirements. Finally, hypothetical decomposition pathways of the various silanes used are discussed.
Identification of a crystal cell‐specific enhancer of the black cells prophenoloxidase gene in drosophila
Authors: Gajewski Kathleen M. , Sorrentino Richard P. , Lee Joong H. , Zhang Qian , Russell Mark , Schulz Robert A.
Published: April 2007

In Drosophila, Black cells (Bc) encodes a Prophenoloxidase and is expressed late in the maturation of crystal cells, which are blood cells involved in wound healing and immune encapsulation. Enhancer analysis of Bc revealed a 1,025‐bp upstream sequence that regulates gene expression in a crystal cell exclusive pattern. Expression of this fragment is altered by mutations in the GATA family serpent (srp) and RUNX family lozenge (lz) genes; Srp and Lz are required for crystal cell specification. Deletional analysis uncovered a 330‐bp crystal cell‐specific sequence, which contains two GATA and three Lz binding sites. Mutational analysis revealed that both GATA sites are necessary, but not sufficient for crystal cell expression. However, one of the Lz sites is essential for crystal cell expression. Thus, Srp and Lz do not just specify the crystal cell lineage, but also regulate the later differentiation of these cells. Additionally, we now have a sensitive tool for marking crystal cells in live animals. genesis 45:200–207, 2007. Published 2007 Wiley‐Liss, Inc.
Syntheses, Structures and Optical Nonlinearities of Heteroselenometallic W–Se–Cu Cluster Compounds Containing Bridging Phosphane Ligands
Authors: Yu Zhan , Zhang Qian‐Feng , Song Yinglin , Wong Wai‐Yeung , Rothenberger Alexander , Leung Wa‐Hung
Published: April 2007

Treatment of [Et4N]2[WSe4] with the trinuclear trigonal‐bipyramidal copper(I) complexes [Cu3(μ3‐X)2(μ‐L)3]X [X = I, L = bis(diphenylphosphanyl)methane (dppm) (1a); X = Cl, L = bis(diphenylphosphanyl)amine (dppa) (1b)] affords the tetranuclear cluster compounds [(μ3‐WSe4)Cu3(μ‐X)(μ‐L)2] [X = I, L = dppm (2a); X = Cl, L = dppa (2b)], which exhibit an open butterfly configuration. Interaction of [Et4N]2[WSe4] with [Cu(MeCN)4][PF6] and L gives the pentanuclear cluster compounds [(μ4‐WSe4)Cu4(μ‐L)4][PF6]2 [L = dppm (3a), dppa (3b)] which contain an open co‐planar WCu4 core. The solid‐state structures of cluster compounds 2a, 2b, and 3a have been established by X‐ray crystallography. The nonlinear optical properties of 2a and 3a have been examined by z‐scan techniques with 7‐ns pulses at 532 nm. The pentanuclear co‐planar cluster 3a exhibits a large optical limiting effect (the limiting threshold is about 0.40 J cm–2). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Aiding Factors in the Formation of Azaplatinacyclobutane Rings – X‐ray and Crystal Structure of [Pt{CH(Ph)CH2NEt2‐κC,κN}(N,N,N′,N′‐tetramethylethylenediamine)]+ and of Its Open‐Chain Precursor
Authors: Lorusso Giuseppe , Barone Carmen R. , Di Masi Nicola G. , Pacifico Concetta , Maresca Luciana , Natile Giovanni
Published: April 2007

The addition products 2 of a secondary amine to a coordinated olefin, in the cationic complexes [PtCl(η2‐CH2=CHR)(tmeda)]+ (tmeda = N,N,N′,N′‐tetramethylethylenediamine; R = Me, 1a; Ph, 1b, H, 1c), undergo in basic medium an intramolecular nucleophilic substitution with elimination of the chlorido ligand and formation of an azaplatinacyclobutane ring 3. The ring‐closing process occurs notwithstanding the absence of a labilizing ligand trans to the leaving chlorido ligand and of bulky substituents on the amino–ethanide chain. If the addition product 2 is a mixture of Markovnikov and anti‐Markovnikov isomers, the ring‐closing reaction is faster for the anti‐Markovnikov form, and this leads to an increase of the relative amount of the anti‐Markovnikov isomer in the cyclized species 3. The difference in the rate of formation of the azaplatinacyclobutane ring between the two isomers has been interpreted on the basis of a more favorable stereochemistry in the case of the anti‐Markovnikov form. The X‐ray crystal structures of [Pt{CH(Ph)CH2NEt2‐κC,κN}(tmeda)]+ (3bn) and of its open‐chain precursor, [PtCl{CH(Ph)CH2NHEt2}(tmeda)]+ (2bn) fully support this hypothesis.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
An experimental investigation into earthquake‐induced failure of medium to low height concrete gravity dams
Authors: Mir Riyaz A. , Taylor C. A.
Published: April 2007

A suitable model material was developed to construct scaled models of a 30 m high prototype concrete gravity dam monolith and the experimental technique perfected for testing the models, till failure, on the EPSRC earthquake simulator at Bristol University. A series of shaking table tests was performed with the aim of assessing the possible failure mechanisms of medium to low height dams under simple motions and simulated earthquakes. Tests were conducted with and without the presence of hydrostatic pressure. The hydrodynamic pressure was simulated using Westergaard's added mass approach. Base cracking was observed to be the main failure mechanism and a tendency of the models to slide and rock after the full crack development at the interface was also observed in some cases.
Seismic response of pile groups under oblique‐shear and Rayleigh waves
Authors: Makris Nicos , Badoni Deepak
Published: April 2007

A simple analytical solution is presented to calculate the pile‐soil‐pile interaction and eventually the dynamic response of pile groups when excited by the passage of Rayleigh waves and obliquely incident SH‐waves. A dynamic Winkler model, with realistic frequency‐dependent ‘springs’ and ‘dashpots’ in conjunction with physically motivated approximations is utilized to compute the wave field radiating from an oscillating pile and the effect of this field on an adjacent pile. The coupled rocking motion of the pile group resulting from Rayleigh waves and the torsional motion of the pile group resulting from SH‐waves is accurately predicted by a simple mathematical expression. The results of the presented method can be obtained with ‘hand calculations’ and are in excellent agreement with results from ‘rigorous’ solutions based on integral equation formulations. It is found that the group response is primarily affected from the phase difference of the input seismic motion at the location of each pile (wave‐passage effect). Pile‐soil‐pile interaction has insignificant effect and can be neglected.
The properties of tuned liquid dampers using a TMD analogy
Authors: Sun L. M. , Fujino Y. , Chaiseri P. , Pacheco B. M.
Published: April 2007

Liquid motions in shallow Tuned Liquid Dampers (TLDs) with rectangular, circular, and annular tanks, subject to harmonic base excitation, are measured experimentally. Using a Single‐Degree‐of‐Freedom (SDOF) Tuned Mass Damper (TMD) analogy, equivalent mass, stiffness and damping of the TLD are calibrated from the experimental results. These parameters are functions of the TLD base amplitude. Some important properties of the TLD are discussed on the basis of these results.
Displacement‐based seismic design of multi‐degree‐of‐freedom bridge structures
Authors: Calvi G. M. , Kingsley G. R.
Published: April 2007

The concept of displacement‐based design is attractive for seismic design, primarily because it places the focus of design directly on displacement demand, and hence damage, rather than on force‐reduction or behaviour factors. A procedure is presented which extends the simple concept of displacement‐based design to complex multi‐degree‐of‐freedom (MDOF) bridge structures. The procedure is based on the assumption of a displaced shape for the structure, and the subsequent reduction of the system to an equivalent single‐degree‐of‐freedom (SDOF) system. The process is shown to work well for the design of a symmetrical bridge, while suffering some shortcomings when applied to a highly irregular bridge. The topic of design‐oriented displacement response spectra is also briefly addressed.
The finite sample properties of the GARCH option pricing model
Authors: Dotsis George , Markellos Raphael N.
Published: April 2007

The authors explore the finite sample properties of the generalized autoregressive conditional heteroscedasticity (GARCH) option pricing model proposed by S. L. Heston and S. Nandi (2000). Simulation results show that the maximum likelihood estimators of the GARCH process may contain substantial estimation biases, even when samples as large as 3,000 observations are used. However, it was found that these biases cause significant mispricings only for short‐term, out‐of‐the‐money options. It is shown that, given an adequate estimation sample, this bias can be reduced considerably by employing the jackknife resampling method. © 2007 Wiley Periodicals, Inc. Jrl Fut Mark 27:599–615, 2007
The information content of option implied volatility surrounding the 1997 Hong Kong stock market crash
Authors: Fung Joseph K. W.
Published: April 2007

This study examines the information conveyed by options and examines their implied volatility at the time of the 1997 Hong Kong stock market crash. The author determines the efficiency of implied volatility as a predictor of future volatility by comparing it to other leading indicator candidates. These include volume and open interest of index options and futures, as well as the arbitrage basis of index futures. Using monthly, nonoverlapping data, the study reveals that implied volatility is superior to those variables in forecasting future realized volatility. The study also demonstrates that a simple signal extraction model could have produced useful warning signals prior to periods of extreme volatility. These results indicate that the options market is highly efficient informationally. © 2007 Wiley Periodicals, Inc. Jrl Fut Mark 27:555–574, 2007
Resident stromal cell‐derived MMP‐9 promotes the growth of colorectal metastases in the liver microenvironment
Authors: Gorden D. Lee , Fingleton Barbara , Crawford Howard C. , Jansen Duco E. , Lepage Martin , Matrisian Lynn M.
Published: April 2007

Colorectal cancer, the second leading cause of cancer deaths in the United States, has a high probability of metastasizing to the liver. Matrix metalloproteinases (MMPs) are a family of zinc dependent endopeptidases that are implicated in cancer metastasis and many aspects of tumor progression. Using a splenic injection experimental metastasis model, mice that are genetically deficient in MMP‐9 demonstrated a nearly 2‐fold decrease in liver weight compared with wild type (WT) mice following injection with MC38 syngeneic colorectal cancer cells. Bioluminesence imaging data demonstrates an early negative effect on tumor growth in MMP‐9 null mice when compared with WT controls. Reconstitution of the bone marrow in MMP‐9−/− mice with cells competent to produce MMP‐9 did not recapitulate the WT phenotype of overwhelming burden of metastatic disease in the liver. In situ hybridization revealed the presence of MMP‐9 mRNA in both MC38 tumor cells and in surrounding stromal cells, and immunostaining with anti MMP‐9 was consistent with MMP‐9 expression by resident liver Kupffer cells. Stromal‐derived MMP‐9 contributes to the establishment and growth of colorectal metastases in the liver. Stromal MMP‐9 was derived from resident cells, most likely Kupffer cells, as opposed to infiltrating bone marrow‐derived cells and the effect of stromal MMP‐9 was independent of expression of MMP‐9 by tumor cells. Stromal‐derived MMP‐9 may represent an important target for selective inhibition in the treatment of metastases. © 2007 Wiley‐Liss, Inc.
In vitro and in vivo evaluation and a case report of intense nanosecond pulsed electric field as a local therapy for human malignancies
Authors: Garon Edward B. , Sawcer David , Vernier P. Thomas , Tang Tao , Sun Yinghua , Marcu Laura , Gundersen Martin A. , Koeffler H. Phillip
Published: April 2007

When delivered to cells, very short duration, high electric field pulses (nanoelectropulses) induce primarily intracellular events. We present evidence that this emerging modality may have a role as a local cancer therapy. Five hematologic and 16 solid tumor cell lines were pulsed in vitro. Hematologic cells proved particularly sensitive to nanoelectropulses, with more than a 60% decrease in viable cells measured by MTT assay 96 hr after pulsing in 4 of 5 cell lines. In solid tumor cell lines, 10 out of 16 cell lines had more than a 10% decrease in viable cells. AsPC‐1, a pancreatic cancer cell line, demonstrated the greatest in vitro sensitivity among solid tumor cell lines, with a 64% decrease in viable cells. When nanoelectropulse therapy was applied to AsPC‐1 tumors in athymic nude mice, responses were seen in 4 of 6 tumors, including clinical complete responses in 3 of 6 animals. A single human subject applied nanoelectropulse therapy to his own basal cell carcinoma and had a complete pathologic response. In summary, we demonstrate that electric pulses 20 ns or less kill a wide variety of human cancer cells in vitro, induce tumor regression in vivo, and show efficacy in a single human patient. Therefore, nanoelectropulse therapy deserves further study as a potentially effective cancer therapy. © 2007 Wiley‐Liss, Inc.
Epstein‐Barr virus B95.8 produced in 293 cells shows marked tropism for differentiated primary epithelial cells and reveals interindividual variation in susceptibility to viral infection
Authors: Feederle Regina , Neuhierl Bernhard , Bannert Helmut , Geletneky Karsten , Shannon‐Lowe Claire , Delecluse Henri‐Jacques
Published: April 2007

Epstein‐Barr virus (EBV), a well‐characterised B‐lymphotropic agent is aetiologically linked to B cell lymphoproliferations, but the spectrum of diseases the virus causes also includes oral hairy leukoplakia, a benign epithelial lesion, as well as carcinomas of the nasopharynx and of the stomach. However, it is still unclear how EBV accesses and transforms primary epithelial cells. Sixteen samples consisting of primary epithelial cells from the sphenoidal sinus or from tonsils were infected with GFP‐tagged recombinant B95.8 EBVs produced in the 293 cell line. The rate of infection was assessed by counting GFP‐positive cells and cells expressing viral proteins. Primary epithelial cells from all samples were found to be sensitive to EBV infection but there was a marked interindividual variation among the tested samples (2–48% positive cells). This suggests heterogeneity in terms of sensitivity to EBV infection in vivo and therefore possibly to EBV‐associated diseases of the epithelium. The virus showed a preferential tropism for differentiated epithelial cells (p63 negative, involucrin positive). In all cases, infected cells expressed EBV lytic proteins but also the LMP1 protein. The viral tropism for differentiated cells and the permissivity of these cells for virus replication reproduced in vitro cardinal features of oral hairy leukoplakia. We have identified a source of EBV that shows unusually strong epitheliotropism for primary epithelial cells that will allow detailed analysis of virus‐cell interactions during virus infection, replication and virus‐mediated transformation. © 2007 Wiley‐Liss, Inc.
A specific inducible nitric oxide inhibitor, ONO‐1714 attenuates inflammation‐related large bowel carcinogenesis in male ApcMin/+ mice
Authors: Kohno Hiroyuki , Takahashi Mami , Yasui Yumiko , Suzuki Rikako , Miyamoto Shingo , Kamanaka Yoshihisa , Naka Masao , Maruyama Takayuki , Wakabayashi Keiji , Tanaka Takuji
Published: April 2007

It is generally assumed that inflammation influences carcinogenesis. We previously reported that dextran sodium sulfate (DSS) strongly enhances colon carcinogenesis in the ApcMin/+ mice and the over‐expression of inducible nitric oxide synthase (iNOS) contributes to this enhancement. In the current study, we investigated the effect of a selective iNOS inhibitor, ONO‐1714 on colitis‐related colon carcinogenesis in the ApcMin/+ mouse treated with DSS. Male C57BL/6J ApcMin/+ and Apc+/+ mice were exposed to 1% DSS in their drinking water for 7 days. ONO‐1714 was given to the mice at a dose level of 50 or 100 ppm in diet for 5 weeks (during the administration of DSS). The tumor inhibitory effects by ONO‐1714 were assessed at week 5 by counting the incidence and multiplicity of colonic neoplasms. Additionally, we assessed serum lipid levels and colonic mRNA expression for cyclooxygenase (COX)‐2, iNOS, tumor necrosis factor (TNF)‐α and interleukin (IL)‐1β. Feeding with ONO‐1714 significantly inhibited the occurrence of colonic adenocarcinoma in a dose‐dependent manner in the ApcMin/+ mice. In addition, the treatment with ONO‐1714 significantly lowered the serum triglyceride levels and mRNA expression levels of COX‐2, TNFα and IL‐1β of colonic mucosa in the DSS‐treated ApcMin/+ mice. Neither ONO‐1714 nor DSS affected the colonic pathology in the Apc+/+ mice. Our findings may suggest that ONO‐1714 could therefore serve as an effective agent for suppression of colitis‐related colon cancer development in the ApcMin/+ mice. © 2007 Wiley‐Liss, Inc.
Combined evaluation of Rad51 and ERCC1 expressions for sensitivity to platinum agents in non‐small cell lung cancer
Authors: Takenaka Tomoyoshi , Yoshino Ichiro , Kouso Hidenori , Ohba Taro , Yohena Tomofumi , Osoegawa Atsushi , Shoji Fumihiro , Maehara Yoshihiko
Published: April 2007

DNA repair enzyme expression in tumor cells possibly affects sensitivity to anti‐cancer agents. The aim of this study was to determine the relationship between expression status of DNA repair enzymes and chemosensitivity in patients with non‐small cell lung cancer (NSCLC). NSCLC tissues prepared from the surgical specimens of 41 patients were subjected to immunohistochemical analysis for Rad51 and ERCC1 proteins and to a chemosensitivity test using the MTT assay. The relationships between the expression status of the DNA repair enzymes and ex vivo chemosensitivity to various agents were evaluated. A positive expression for Rad51 and ERCC1 was observed in 17 cases (41%) and 20 cases (49%), respectively. The positivity of Rad51 was closely related to a certain histologic type of squamous cell carcinoma and poor differentiation, and the positivity of ERCC1 tended to be related to squamous cell carcinoma. In chemosensitivity tests, sensitivities to CDDP and CBDCA were significantly lower when both 2 enzymes were positive (p = 0.012 and 0.04 in CDDP, 0.014 and 0.03 in CBDCA). Both Rad51 and ERCC1 expressions showed no significant relationship with sensitivities to paclitaxel, etoposide, vinorelbine, gemcitabine, 5‐FU, or irinotecan. In conclusion, combined expression of Rad51 and ERCC1 expression is associated with resistance to platinum agents in the ex vivo study of clinical NSCLC, and evaluation of expression status of both DNA repair enzymes would be a predictor for clinical response to platinum‐based chemotherapies. © 2007 Wiley‐Liss, Inc.
Second neoplasms after oesophageal cancer
Authors: Levi Fabio , Randimbison Lalao , Maspoli Manuela , Te Van‐Cong , Vecchia Carlo La
Published: April 2007

The authors considered the incidence of second neoplasms among 1,672 oesophageal cancers diagnosed between 1974 and 2004 in the Cancer Registries of the Swiss Cantons of Vaud and Neuchâtel, and followed‐up to 2004. A total of 141 second neoplasms were observed versus 38.5 expected, corresponding to a standardized incidence ratio (SIR) of 3.7 (95% confidence interval: 3.1–4.3). The SIRs were statistically significant for cancers of the oral cavity and pharynx (57.3), larynx (24.3), lung (6.6) and intestines (2.6). The SIRs were higher in subjects diagnosed below age 50 and in the first year after diagnosis. The SIR of upper digestive and respiratory tract neoplasms was higher for oesophageal cancers diagnosed in the upper (87.5) and middle (68.1), as compared with the lower third (19.4). There was no rise of second oral, pharyngeal and laryngeal cancer with advancing age, and their incidence tended indeed to decline from 100/1,000 at age 40–49 to 25/1,000 at age 70–79. There was no tendency to rise with age in the incidence of first oesophageal cancer in subjects who subsequently developed another upper digestive or respiratory tract neoplasm. The excess risks of upper digestive and respiratory tract neoplasms are attributable to increased diagnosis and registration of second neoplasms following a diagnosis of oesophageal cancer, as well as to heavy tobacco and alcohol consumption in oesophageal cancer cases. The absence of rise in incidence with age is also compatible with the existence of a subset of the population of susceptible individuals. © 2007 Wiley‐Liss, Inc.
hOGG1 Ser326Cys polymorphism and susceptibility to gallbladder cancer in a Chinese population
Authors: Jiao Xingyuan , Huang Jiefu , Wu Shengli , MingdeLv  , Hu Yize , Jianfu  , Su Xiaokang , Luo Canqiao , Broelsch CE
Published: April 2007

The human oxoguanine glycosylase 1(hOGG1) gene encodes a DNA glycosylase that is involved in excision repair of 8‐OH‐dG (8‐hydroxy‐2‐deoxyguanine) from oxidatively‐damaged DNA. To determine whether hOGG1 plays a role in the risk for adenocarcinoma of the gallbladder, we tested the association of this polymorphism with gallbladder cancer in a Chinese population‐based, case control study of 204 cases and 209 controls. The subjects were genotyped with a polymerase chain reaction‐restriction fragment length polymorphism (PCR–RELP) assay. The association between the genetic polymorphism of this gene and risk of the cancer was examined by using a multivariate analysis. We found that the distribution of hOGG1 Ser326Cys genotypes among controls (Ser/Ser, 37.3%; Ser/Cys, 53.6% and Cys/Cys, 9.1%) was significantly different from that among gallbladder cancer cases (Ser/Ser, 43.1%; Ser/Cys, 36.3% and Cys/Cys, 20.6%). Significantly increased risk for gallbladder cancer was both the hOGG1 326Ser/Cys (Odds ratio [OR] = 1.9, 95% confidence interval (CI) = 1.0–3.7) and hOGG1 326Cys/Cys genotypes (OR = 4.5, 95% CI = 1.1–22.4). We observed no statistically significant association between hOGG1 genotype and gallbladder cancer association in gallstone absence. In contrast, a near‐significant increase in risk for gallbladder cancer was observed for gallstone presence with the hOGG1 326Ser/Cys genotype (OR = 2.2, CI = 1.4–3.5) whereas a significant increase in association for gallbladder cancer was observed for gallstone presence with the 326Cys/Cys genotype (OR = 6.1, CI = 2.1–27.2). These data corresponded with the fact that a significant trend towards increased association for gallbladder cancer was observed with potentially higher‐risk hOGG1 genotypes in gallstone presence(p < 0.001, χ2 trend test)but not in gallstone absence(p = 0.89, χ2 trend test). A significant increase in risk for gallbladder cancer was observed for larger gallstone (those with stone diameters 2 cm or greater) with the hOGG1 326Ser/Cys(OR = 1.9, 95% CI = 1.1–2.9) and hOGG1 326Cys/Cys genotypes(OR = 5.9, 95% CI = 1.6–18.0). These data are consistent with the observation that a significant trend towards increased risk for gallbladder cancer was observed with potentially higher‐risk hOGG1 genotypes in gallbladder cancer patients with larger gallstone (p < 0.001, χ2 trend test). However, we observed no statistically significant association between hOGG1 genotype and gallbladder cancer risk in gallbladder cancer patients with smaller gallstone (those with stone diameters 2 cm smaller) (hOGG1 326Ser/Cys:OR = 2.2, 95% CI = 0.8–4.0; hOGG1 326Cys/Cys:OR = 2.9, 95% CI = 0.6–29.4; p = 0.06, χ2 tread test). These results suggest that hOGG1 Ser326Cys polymorphism is associated with gallbladder cancer risk. © 2007 Wiley‐Liss, Inc.