bluuebunny/crossref_metadata_2025 huggingface dataset:
Micelles for the Self‐Assembly of “Off–On–Off” Fluorescent Sensors for pH Windows
Authors: Diaz‐Fernandez Yuri , Foti Francesco , Mangano Carlo , Pallavicini Piersandro , Patroni Stefano , Perez‐Gramatges Aurora , Rodriguez‐Calvo Simon
Published: September 2005

A micellar approach is proposed to build a series of systems featuring an “off–on–off” fluorescent window response with changes in pH. The solubilizing properties of micelles are used to self‐assemble, in water, plain pyrene with lipophilized pyridine and tertiary amine moieties. Since these components are contained in the small volume of the same micelle, pyrene fluorescence is influenced by the basic moieties: protonated pyridines and free tertiary amines behave as quenchers. Accordingly, fluorescence transitions from the “off” to the “on” state, and viceversa, take place when the pH crosses the pKa values of the amine and pyridine fragments. To obtain an “off–on–off” fluorescent response in this investigation we use either a set of dibasic lipophilic molecules (containing covalently linked pyridine and tertiary amine groups) or combinations of separate, lipophilic pyridines and tertiary amines. The use of combinations of dibasic and monobasic lipophilic molecules also gives a window‐shaped fluorescence response with changes in pH: it is the highest pyridine pKa and the lowest tertiary amine pKa that determine the window limits. The pKa values of all the examined lipophilic molecules were determined in micelles, and compared with the values found for the same molecules in solvent mixtures in which they are molecularly dispersed. The effect of micellization is to significantly lower the observed protonation constants of the lipophilized species. Moreover, the more lipophilic a molecule is, the lower the observed logK value is. Accordingly, changing the substituents on the basic moieties or modifying their structure, tuning the lipophilicity of the mono‐ or dibases, and choosing among a large set of possible combination of lipophilized mono‐ and dibases have allowed us to tune, almost at will, both the width and the position along the pH axis of the obtained fluorescent window.
Silver Nanocluster Redox‐Couple‐Promoted Nonclassical Electron Transfer: An Efficient Electrochemical Wolff Rearrangement of α‐Diazoketones
Authors: Sudrik Surendra G. , Chaki Nirmalya K. , Chavan Vilas B. , Chavan Sambhaji P. , Chavan Subhash P. , Sonawane Harikisan R. , Vijayamohanan K.
Published: September 2005

In this work we report the unique electrocatalytic role of benzoic acid protected silver nanoclusters (Agn, mean core diameter 2.5 nm) in the Wolff rearrangement (Scheme 1) of α‐diazoketones. More specifically, the presence of a Agn0/Agn+ redox couple facilitates a nonclassical electron‐transfer process, involving chemical reaction(s) interposed between two electron‐transfer steps occurring in opposite directions. Consequently, the net electron transfer between the electron mediator (Agn) and α‐diazoketone is zero. In‐situ UV‐visible studies using pyridine as a nucleophilic probe indicate the participation of α‐ketocarbene/ketene as important reaction intermediates. Controlled potential coulometry of α‐diazoketones using Agn as the anode results in the formation of Wolff rearranged carboxylic acids in excellent yield, without sacrificing the electrocatalyst.
A Promising MgII‐Ion‐Selective Luminescent Probe: Structures and Properties of Dy–Mn Polymers with High Symmetry
Authors: Zhao Bin , Gao Hong‐Ling , Chen Xiao‐Yan , Cheng Peng , Shi Wei , Liao Dai‐Zheng , Yan Shi‐Ping , Jiang Zong‐Hui
Published: September 2005

Two Dy–Mn polymers, {[Dy(L1)3Mn1.5(H2O)3]⋅3.125 H2O}n (1, L1=pyridine‐2,6‐dicarboxylic acid) and {[Dy(L2)3Mn1.5(H2O)6]⋅8.25 H2O}n (2, L2=4‐hydroxylpyridine‐2,6‐dicarboxylic acid), with high symmetry (S6) have been prepared. Polymer 1 has a nanoporous 3D framework with channel of about 17.6 Å diameter, while 2 has a honeycomb‐type 2D structure with the cavity of approximately 14.4 Å diameter. In the construction of multidimensional porous polymers with 3d–4f mixed metals, it is the first observation that a ligand substituent effect leads to dramatic differences in the structures formed. Luminescent studies reveal that the emission intensities of 1 and 2 increase significantly upon the addition of Mg2+, whereas the introduction of other metal ions leaves the intensity unchanged or even weakens it; hence, both of them may serve as good candidates of Mg2+ luminescent probes. To our knowledge, complex 1 is also the first example of a 3d–4f metal‐based nanoporous polymer to exhibit luminescent selectivity for Mg2+. Magnetic susceptibility measurements reveal a rather rare ferromagnetic interaction in 2. Thermal gravimetric analyses and powder X‐ray diffraction investigations have also been performed, suggestive of high thermal stability of 1.
Anhydrous Phosphazenium Fluorides as Sources for Extremely Reactive Fluoride Ions in Solution
Authors: Schwesinger Reinhard , Link Reinhard , Wenzl Peter , Kossek Sebastian
Published: September 2005

Several peralkylated polyaminophosphazenium cations were evaluated for the generation of novel anhydrous F−salts. Two of them have been characterized by X‐ray analysis and are particularly soluble, even in apolar aprotic solvents like benzene or THF, one of them even at −30 °C. Such solutions probably represent the most basic metal‐free and stable media known to date. Comparison of these fluorides with known F−sources demonstrates that they are of unprecedented reactivity and selectivity in E2 elimination reactions.
DNA transitions induced by binding of PARP‐1 to cruciform structures in supercoiled plasmids
Authors: Chasovskikh Sergey , Dimtchev Alexandre , Smulson Mark , Dritschilo Anatoly
Published: September 2005

Background

Poly(ADP‐ribose)polymerase‐1 (PARP‐1) binds to single and double‐stranded breaks in DNA, but less well known is its affinity for undamaged DNA. Previously, we have shown that PARP‐1 also binds to the hairpin structures in DNA models. The mechanism underlying these interactions remains to be defined.

Methods

We analyzed atomic force microscopy (AFM) images of complex of PARP‐1 proteins with supercoiled plasmids containing cruciform structures. Using volume measurement analysis of molecules of PARP‐1, we determined the numbers of PARP‐1 molecules interacting with supercoiled DNA plasmids containing one cruciform structure. We also determined the extent of supercoiling of plasmids.

Results

Our observations show that PARP‐1 binds to sequences that transition from B‐DNA to cruciform structures. PARP‐1 is present at the ends of hairpin arms, sites containing a 4‐base single‐stranded DNA. Furthermore, interaction of PARP‐1 with supercoiled plasmids leads to a more relaxed plasmid‐DNA conformation.

Conclusions

Binding of PARP‐1 to cruciform DNA offers insight into possible mechanisms underlying with changes in DNA conformation. These observations may offer insight into mechanisms involving DNA conformation related to process such as DNA repair and transcription. © 2005 Wiley‐Liss, Inc.
X‐ray phase identification of chocolate is possible without the removal of sugar
Authors: Guthrie Sarah E. , Mazzanti Gianfranco , Idziak Stefan H. J.
Published: September 2005

When examining chocolate samples by means of X‐ray diffraction, it has become common practice for any sugar to be removed through repeated rinsing in cold water. While necessary in some cases, we show that it is possible to determine the phase of certain dark chocolate samples without sugar removal, through examination of distinctive X‐ray diffraction peaks corresponding to lattice spacings of 3.98 and 3.70 Å.
Optimal design of supplemental viscous dampers for linear framed structures
Authors: Lavan Oren , Levy Robert
Published: September 2005

A methodology for the optimal design of supplemental viscous dampers for framed structures is presented. It addresses the problem of minimizing the added damping subject to a constraint on the maximal interstorey angular drift for an ensemble of realistic ground motion records while assuming linear behaviour of the damped structure. The solution is achieved by actually solving an equivalent optimization problem of minimizing the added damping subject to a constraint on a maximal weighted integral on the squared angular drift. The computational effort is appreciably reduced by first using one ‘active’ ground motion record. If the resulting optimal design fails to satisfy the constraints for other ground motions from the original ensemble, additional ground motions (loading conditions) are added one by one to the ‘active’ set until the optimum is reached. An efficient selecting process which is presented herein will usually require one or two records to attain an optimum design.

Examples of optimal designs of supplemental dampers are presented for a 2‐storey shear frame and a 10‐storey industrial frame. The 2‐storey shear frame is required to withstand one given ground motion whereas the 10‐storey frame is required to withstand an ensemble of twenty ground motions. The resulting viscously damped structures have envelope values of interstorey drifts equal or less than the target drifts. Copyright © 2005 John Wiley & Sons, Ltd.
Time‐harmonic response of non‐homogeneous elastic unbounded domains using the scaled boundary finite‐element method
Authors: Bazyar Mohammad Hossein , Song Chongmin
Published: September 2005

The scaled boundary finite‐element method is extended to simulate time‐harmonic responses of non‐homogeneous unbounded domains with the elasticity modulus and mass density varying as power functions of spatial coordinates. The unbounded domains and the elasticity matrices are transformed to the scaled boundary coordinates. The scaled boundary finite‐element equation in displacement amplitudes are derived directly from the governing equations of elastodynamics. To enforce the radiation condition at infinity, an asymptotic expansion of the dynamic‐stiffness matrix for high frequency is developed. The dynamic‐stiffness matrix at lower frequency is obtained by numerical integration of ordinary differential equations. Only the boundary is discretized yielding a reduction of the spatial dimension by one. No fundamental solution is required. Material anisotropy is modelled without additional efforts. Examples of two‐ and three‐dimensional non‐homogeneous isotropic and transversely isotropic unbounded domains are presented. The results demonstrate the accuracy and simplicity of the scaled boundary finite‐element method. Copyright © 2005 John Wiley & Sons, Ltd.
Macro–micro analysis method for wave propagation in stochastic media
Authors: Ichimura T. , Hori M.
Published: September 2005

This paper presents a new analysis method, called macro–micro analysis method (MMAM) for numerical simulation of wave propagation in stochastic media, which could be used to predict distribution of earthquake strong motion with high accuracy and spatial resolution. This MMAM takes advantage of the bounding medium theory (BMT) and the singular perturbation expansion (SPE). BMT can resolve uncertainty of soil and crust structures by obtaining optimistic and pessimistic estimates of expected strong motion distribution. SPE leads to efficient multi‐scale analysis for reducing a huge amount of computation. The MMAM solution is given as the sum of waves of low resolution covering a whole city and waves of high resolution for each city portion. This paper presents BMT and SPE along with the formulation of MMAM for wave propagation in three‐dimensional elastic media. Application examples are presented to verify the validity of the MMAM and demonstrate potential usefulness of this approach. In a companion paper (Earthquake Engng. Struct. Dyn., this issue) application examples of earthquake strong motion prediction are also presented. Copyright © 2005 John Wiley & Sons, Ltd.
Analytical expression between the impact damping ratio and the coefficient of restitution in the non‐linear viscoelastic model of structural pounding
Authors: Jankowski Robert
Published: September 2005

Earthquake‐induced structural pounding has been recently intensively studied with the help of different models of impact force. It has been verified through comparisons, that the non‐linear viscoelastic model may be considered somewhat the most accurate one among them. The aim of this short paper is to derive an approximating formula relating the impact damping ratio, as a parameter of the model mentioned, with a more widely used coefficient of restitution. The accuracy of the derived analytical formulation has been confirmed through the comparison with the results of numerical simulations. Copyright © 2005 John Wiley & Sons, Ltd.
Pressure boundary condition for the time‐dependent incompressible Navier–Stokes equations
Authors: Sani R. L. , Shen J. , Pironneau O. , Gresho P. M.
Published: September 2005

In Gresho and Sani (Int. J. Numer. Methods Fluids 1987; 7:1111–1145; Incompressible Flow and the Finite Element Method, vol. 2. Wiley: New York, 2000) was proposed an important hypothesis regarding the pressure Poisson equation (PPE) for incompressible flow: Stated there but not proven was a so‐called equivalence theorem (assertion) that stated/asserted that if the Navier–Stokes momentum equation is solved simultaneously with the PPE whose boundary condition (BC) is the Neumann condition obtained by applying the normal component of the momentum equation on the boundary on which the normal component of velocity is specified as a Dirichlet BC, the solution (u, p) would be exactly the same as if the ‘primitive’ equations, in which the PPE plus Neumann BC is replaced by the usual divergence‐free constraint (∇ · u = 0), were solved instead.

This issue is explored in sufficient detail in this paper so as to actually prove the theorem for at least some situations. Additionally, like the original/primitive equations that require no BC for the pressure, the new results establish the same thing when the PPE approach is employed. Copyright © 2005 John Wiley & Sons, Ltd.
The relationship of MPDATA to other high‐resolution methods
Authors: Rider W. J.
Published: September 2005

High‐resolution methods have produced the ability to conduct large eddy simulations without the benefit of an explicit subgrid model. This capability is known as implicit large eddy simulation (ILES). A number of high‐resolution methods have been shown to have this property. There are notable exceptions where high‐resolution method do not work as ILES, particularly methods that have a leading 𝒪(h2) dissipative term. On the other hand, MPDATA is an effective ILES method with a leading 𝒪(h2) dissipative term. This dichotomy has played a key role in the discovery of the key role of conservation or control volume form in producing ILES results. In the process of this analysis, I describe a variant of the method leading to a useful alternative form of sign‐preserving limiters. This form is proposed as an extension of the basic MPDATA methodology allowing some flexibility in the choice of effective high‐order methods. This multistage version of the algorithm removes the leading order nonlinear dissipative error. I rediscover the recursive form of the MPDATA iteration through modified equation analysis (MEA). Finally, returning to the original purpose of the analysis, I describe how the different principles used in MPDATA have been an important contributor to the recent theoretical understanding of ILES.

MPDATA is compared with monotone high‐resolution methods both analytically and computationally. The numerical comparison focuses on the validation of ILES methods for high Reynolds number decaying isotropic turbulence. Copyright © 2005 John Wiley & Sons, Ltd.
It's not justwhatyou do, it's thewaythat you do it: the effect of different payment card formats and survey administration on willingness to pay for health gain
Authors: Smith Richard D.
Published: September 2005

A general population sample of 314 Australian respondents were randomly allocated to complete a contingent valuation survey administered by face‐to‐face or telephone (‘phone‐mail‐phone’) interview. Although the telephone interview was quicker to complete, no significant difference was found in values obtained through either method. Within each sub‐sample, respondents were also randomly allocated to the three different versions of the payment card (PC) questionnaire format: values listed from high‐to‐low, values listed from low‐to‐high and values randomly shuffled. The high‐to‐low version resulted in significantly higher values than the other versions. Further analyses indicate that the randomly shuffled PC version may produce the most ‘valid’ values. Copyright © 2005 John Wiley & Sons, Ltd.
Changes in the expression of plasma membrane calcium extrusion systems during the maturation of hippocampal neurons
Authors: Kip Sertac N. , Gray Noah W. , Burette Alain , Canbay Ali , Weinberg Richard J. , Strehler Emanuel E.
Published: September 2005

Spatial and temporal control of intracellular calcium signaling is essential for neuronal development and function. The termination of local Ca2+ signaling and the maintenance of basal Ca2+ levels require specific extrusion systems in the plasma membrane. In rat hippocampal neurons (HNs) developing in vitro, transcripts for all isoforms of the plasma membrane Ca2+ pump and the Na/Ca2+ exchanger, and the major nonphotoreceptor Na+/Ca2+,K+ exchangers (NCKX) were strongly upregulated during the second week in culture. Upregulation of plasma membrane calcium ATPases (PMCAs)1, 3, and 4 mRNA coincided with a splice shift from the ubiquitous b‐type to the neuron‐specific a‐type with altered calmodulin regulation. Expression of all PMCA isoforms increased over 5‐fold during the first 2 weeks. PMCA immunoreactivity was initially concentrated in the soma and growth cones of developing HNs. As the cells matured, PMCAs concentrated in the dendritic membrane and often colocalized with actin‐rich dendritic spines in mature neurons. In the developing rat hippocampal CA1 region, immunohistochemistry confirmed the upregulation of all PMCAs and showed that by the end of the second postnatal week, PMCAs1, 2, and 3 were concentrated in the neuropil, with less intense staining of cell bodies in the pyramidal layer. PMCA4 staining was restricted to a few cells showing intense labeling of the cell periphery and neurites. These results establish that all major Ca2+ extrusion systems are strongly upregulated in HNs during the first 2 weeks of postnatal development. The overall increase in Ca2+ extrusion systems is accompanied by changes in the expression and cellular localization of different isoforms of the Ca2+ pumps and exchangers. The accumulation of PMCAs in dendrites and dendritic spines coincides with the functional maturation in these neurons, suggesting the importance of the proper spatial organization of Ca2+ extrusion systems for synaptic function and development. © 2005 Wiley‐Liss, Inc.
Activity and plasticity in the CA1, the dentate gyrus, and the amygdala following controllable vs. uncontrollable water stress
Authors: Kavushansky Alexandra , Vouimba Rose‐Marie , Cohen Hagit , Richter‐Levin Gal
Published: September 2005

The level of controllability has been shown to modulate the effects of stress on physiology and behavior. In the present study, we investigated the effects of controllable vs. uncontrollable stressors on plasticity in hippocampal CA1, the dentate gyrus (DG), and basal amygdala nucleus (B) in the rat, using the electrophysiological procedure of long‐term potentiation (LTP). A naive group was left undisturbed until the electrophysiological recording commenced. Rats of the two controllable stress groups were trained in the Morris water maze to locate an invisible underwater platform (the first group), or visible platform (the second group), thus escaping from the water, before the recording. The uncontrollable stress group underwent the same procedure (exposure time to water was adjusted to the averaged exposure time of the first controllable group) without the escape platform. We first assessed the effects of stress and controllability on LTP in CA1. Both controllable stressors and the uncontrollable stress impaired CA1 LTP, with a more robust effect induced by the uncontrollable stress. We further assessed the effects of the same procedures on LTP in DG and B. The uncontrollable stress enhanced LTP in DG and increased baseline responses (suggesting uncontrollable stress‐induced plasticity) in the amygdala. All the stressors decreased amygdalar LTP. An assessment of plasma levels of corticosterone (CORT), following the behavioral procedures, revealed an enhancement in CORT release following the uncontrollable, but not controllable stress, indicating the uncontrollable condition as the most stressful. These findings provide insight into the differential effects of stress and stress controllability on different hippocampal subregions and the amygdala. © 2005 Wiley‐Liss, Inc.
Characterizing behavioral and cognitive dysexecutive changes in progressive supranuclear palsy
Authors: Millar David , Griffiths Philipa , Zermansky Adam J. , Burn David J.
Published: September 2005

Frontal lobe dysfunction is a prominent feature of many neurological disorders. Early diagnosis may be enhanced by establishing a profile of cognitive, behavioral, and emotional change. Traditional psychometric assessment focuses on cognitive dysfunction and fails to identify behavioral changes, particularly those associated with orbitofrontal dysfunction. We examined progressive supranuclear palsy (PSP), a prototypical subcortical dementia with frontal features, using commonly available neuropsychological measures and a modification of the Katz Adjustment Scale‐Relatives (KAS‐R), an instrument first developed to assess dysexecutive changes in head‐injured patients. Executive tests identified deficits in reasoning, planning, set shifting, verbal fluency, information processing speed, and response initiation. On the KAS‐R, changes in apathy, social withdrawal, and independence were observed, with little change in belligerence, social irresponsibility, uncooperativeness, obstreperousness, anxiety, and depression. The results show the potential utility of this instrument in characterizing behavioral and emotional changes associated with frontal lobe dysfunction in neurodegenerative disease. © 2005 Movement Disorder Society
Magnetization transfer effect on human brain metabolites and macromolecules
Authors: McLean Mary A. , Simister Robert J. , Barker Gareth J. , Duncan John S.
Published: September 2005

A pulse sequence was implemented to observe the magnetization transfer (MT) effect on metabolites, water, and macromolecules in human frontal lobes in vivo at 1.5 Tesla. Signals were compared following the application of three hard pulses of 0.745 μT amplitude, applied at frequency offsets of either 2500 Hz or 30 kHz, preceding a conventional point‐resolved spectroscopy (PRESS)‐localized acquisition with an echo time (TE) of 30 ms and repetition time (TR) of 3 s. This gave an MT effect on water in vivo of 46%, while direct saturation by the MT pulses at 2.5 kHz offset was confirmed to be under 4% for all metabolites. We observed significant MT saturation in vivo for N‐acetylated compounds, choline (Cho), myo‐inositol, and lactate (Lac); a trend of an effect on glutamate + glutamine (Glx); and the typically observed effect on creatine (Cr). No significant MT effect was seen on the macromolecule signal, which was observed using metabolite nulling. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.
Error optimization of a three‐dimensional magnetic resonance imaging tagging‐based cartilage deformation technique
Authors: Neu C. P. , Hull M. L. , Walton J. H.
Published: September 2005

Three‐dimensional strain fields in articular cartilage subjected to compressive loading can be determined using a recently developed MRI‐based cartilage deformation by tag registration technique. The objective of this study was to determine the experimental variables that minimize the technique error, which has not been previously reported. Error (strain bias and precision) was determined using direct experiments and Monte Carlo simulations for four variables: spatial resolution, tag line spacing, applied nominal strain, and number of control points used to describe tag lines in a B‐spline model. The important results include the following: (1) bias was not significantly different from zero, (2) precision increased with image resolution and with tag line spacing, (3) precision was independent of applied nominal strain, and (4) error was a minimum (absolute precision = 0.41% strain) for the following values: spatial resolution = 0.05 × 0.05 mm2; tag line spacing = 2.0 mm; control points = 6. With these results the technique can now be used in various applications while minimizing error. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.
Synthesis of a new type of core–shell particle from hyperbranched polyglycerol
Authors: Wan Decheng , Li Zhongyu , Huang Junlian
Published: September 2005

Based on hyperbranched polyglycerol (PG), a route to prepare particles with a novel topology was developed. The hydroxyls of PG were converted to trithiocarbonates, and the latter were used to mediate the surface graft polymerization of N,N‐dimethylaminoethyl acrylate. The poly(N,N‐dimethylaminoethyl acrylate) shell was crosslinked by 1,6‐dibromohexane and then parted from the core by the cleavage of trithiocarbonates with sodium borohydride. Novel particles with thiol groups located on the interface between the PG core and poly(N,N‐dimethylaminoethyl acrylate) shell were thus formed. The shell crosslinking could be performed at very high solid contents (2–4%). These polymer particles showed pH‐ and temperature‐dependent solubility. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5458–5464, 2005
Dual bimodal polyethylene prepared by intercalated silicate with nickel diimine complex
Authors: Wang Qi , Liu Peng
Published: September 2005

The ethylene polymerization was catalyzed by the intercalated montmorillonite with the nickel complex, [ArNC(Me)C(Me)NAr]NiBr2 (Ar = 2,6‐C6H3 (i‐Pr)2). Polymer with low melting point and high molecular weight was produced at the early stage of polymerization followed by formation of polymer with high melting point and low molecular weight. It is proposed that the gallery of silicate lowers the propagation rate of polymerization and frequency of “chain walking” process of nickel complex anchored inside the gallery, which produces polymer with low molecular weight and low branching, whereas the nickel complex immobilized on the surface of silicate generates polymer with high molecular weight and high branching. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5506–5511, 2005
Synthesis of a novel high sensitive photo‐radical initiator with good thermal stability based on naphthalic‐1,8‐N‐alkylimide derivatives
Authors: Sakayori Katsuya , Shibasaki Yuji , Ueda Mitsuru
Published: September 2005

A new high‐sensitive photo‐radical initiator, N‐[2‐(2‐acryloyloxyethoxy)ethyl]‐1,8‐naphthalimide (NI6), with good thermal stability based on naphthylimide derivative was developed. NI6 was prepared by the condensation of N‐[2‐(2‐hydroxyethoxy)ethyl]‐1,8‐naphthalimide and acryloyl chloride in the presence of 4‐dimethylaminopyridine. The film consisting of NI6 and pentaerythritol triacrylate (PETA) showed higher photosensitivity than those containing conventional photo‐radical initiators such as acrylic acid 2‐(2‐{2‐[2‐(4‐benzoyl‐phenoxy)‐ethoxy]‐ethoxy}‐ethoxy)‐ethyl ester, cyclohexylmaleimide, and the resulting film exhibited very high transmittance over 400 nm. The thermal stability of NI6 was very high and no decomposed residues were observed from the film consisting of NI6 after heating at 250 °C for 1 h. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5571–5580, 2005
Ethylene/silane copolymers prepared with a metallocene catalyst as polymeric additives in polyethylene/aluminum trihydroxide composites
Authors: Lipponen S. , Seppälä J.
Published: September 2005

Metallocene catalyst based polyethylene‐co‐7‐octenyldimethylphenylsilane (PE/SiPh) and its post‐treated functional forms PE/SiX (X = Cl, F, OCH3, OCH2CH3) were used as additives in PE/ATH composites. The impact strength of the composites was significantly increased after a small addition (0.5–3.0 wt %) of the functionalized form of the copolymer (PE/SiX). The thermal study of the composites gave us more information about the additive's behavior at the filler/matrix interphase and correlation to the mechanical properties was found. According to this thermal data, the original untreated form of PE/SiPh also seemed to interact weakly with the ATH‐filler particles, which was seen in an altered interphase at the filler/matrix boundary layer. The interaction was not strong enough to improve the impact strength of composites but an increase was observed in some other mechanical properties (tensile stress, yield strain). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5597–5608, 2005
Effect of the initial maleic anhydride content on the grafting of maleic anhydride onto isotactic polypropylene
Authors: Zhang Ronghua , Zhu Yutian , Zhang Jianguo , Jiang Wei , Yin Jinghua
Published: September 2005

A series of 13C‐enriched maleic anhydride grafted isotactic polypropylene samples were prepared in solution at 170 °C by changes in the initial maleic anhydride content. The NMR spectra of the samples showed that the signals of the maleic anhydride attached to the tertiary carbons of the isotactic polypropylene chains increased considerably with increasing maleic anhydride content, whereas the signals of the maleic anhydride on the radical chain ends (with a single bond) arising from β scission did not. On the other hand, the signals of the maleic anhydride on the radical chain ends with double bonds increased markedly with increasing maleic anhydride content, and this suggested that β scission could occur extensively after maleic anhydride was attached to the tertiary carbons. As a result, the molecular weight of the grafted polypropylene decreased significantly with increasing maleic anhydride content in this study. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5529–5534, 2005
Using hydrophobic additive as pore‐forming agent to prepare macroporous PNIPAAm hydrogels
Authors: Zhang Xian‐zheng , Chu Chih‐chang , Zhuo Ren‐xi
Published: September 2005

Hydrophobic poly(lactic acid) nanospheres were fabricated and used as an additive during the polymerization and gelation process of temperature‐sensitive poly(N‐isopropylacrylamide) (PNIPAAm) hydrogels. The influence of hydrophobic additive on properties of PNIPAAm hydrogels was examined. The interior morphology studied by scanning electron microscopy revealed that the hydrophobic additive induced a macroporous structure in the resulting PNIPAAm hydrogels. Results demonstrate that the hydrophobic additive acts as a pore‐forming agent like conventionally used hydrophilic additive does during the gelation process. Because of the macroporous network and incorporated additives, the temperature‐sensitive characteristics, particularly the equilibrium swelling ratio at room temperature and shrinking rate upon temperature increase of modified PNIPAAm hydrogels, are significantly improved. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5490–5497, 2005
Catalytic effect of ionic liquids in the Cu2O/2,2′‐bipyridine catalyzed living radical polymerization of methyl methacrylate initiated with arenesulfonyl chlorides
Authors: Percec Virgil , Grigoras Cristian
Published: September 2005

The effect of 1‐butyl‐3‐methylimidazolium hexafluorophosphate ionic liquid on the living radical polymerization of methyl methacrylate initiated with arenesulfonyl chlorides and catalyzed by the self‐regulated Cu2O/2,2′‐bipyridine catalyst was investigated. A dramatic acceleration of the living radical polymerization of methyl methacrylate in this ionic liquid was discovered. This accelerated living radical polymerization maintained an initiation efficiency of 100%, eliminated the induction period of this catalyst, and produced poly(methyl methacrylate) with molecular weight distribution of 1.1 and perfect bifunctional chain‐ends. The kinetic analysis of the living radical polymerization in the presence of ionic liquid demonstrated a rate constant of propagation that follows an almost first order of reaction on the ionic liquid concentration and therefore, the ionic liquid exhibits catalytic effect. The catalytic effect of the ionic liquid facilitated the reduction of the catalyst concentration from stoichiometric to catalytic and allowed the decrease of the polymerization temperature from 80 to 22 °C. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5609–5619, 2005
X‐ray study of Bi, Sb and Bi1–x–Sbx alloys
Authors: Shankar Narayana M. , Gopi Krishna N.
Published: September 2005

The mean square amplitudes of vibration, Debye–Waller factors and Debye temperatures of bismuth (Bi), antimony (Sb) and Bi1–x –Sbx alloys have been obtained from X‐ray intensities. The intensities have been measured with Philips 3020 diffractometer fitted with a proportional counter using filtered CuKα radiation at room temperature and have been corrected for thermal diffuse scattering. The X‐ray Debye temperatures obtained for Bi and Sb have been compared with corresponding values obtained from specific heats and elastic constants. The values of Debye temperature obtained for Bi1–x –Sbx alloys have been compared with the values calculated from Kopp–Neumann relation. Vacancy formation energies of Bi, Sb and Bi1–x –Sbx alloys have been estimated using a relation connecting it with the X‐ray Debye temperature. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Small‐signal characteristics of organic semiconductors with continuous energy distribution of traps
Authors: Schmeits M. , Nguyen N. D.
Published: September 2005

The electrical characteristics of organic light emitting devices containing a continuous distribution of trap states in the forbidden gap are obtained by numerically solving the basic semiconductor equations for the steady state and under small‐signal conditions. The spatially‐dependent occupied trap states, which are described by an explicit density of states function, modify the charge distribution within the structure and the shape of the electric field and the carrier current densities. The effect of the modulation frequency, the applied voltage and the device temperature are studied for a hole conducting layer with a trap density of states consisting of a double gaussian profile and for a given set of microscopic parameters including the carrier mobilities and thermal velocities, the capture cross sections, and the residual shallow impurity concentration. The frequency‐dependent loss and capacitance curves are obtained for various experimental conditions, like temperature and applied steady‐state voltage. Effects of parameters describing electrical contacts and trap density of states are shown. Such results are particularly useful for the analysis of experimental electrical characteristics obtained by thermal admittance spectroscopy. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Barrier and mechanical properties of methylcellulose–whey protein films
Authors: Erdohan Z. Özge , Turhan K. Nazan
Published: September 2005

Water vapour permeability (WVP) and mechanical properties were assessed in edible films prepared from methylcellulose (MC) and MC–whey protein isolate (WPI) or MC–whey protein concentrate (WPC). Glycerol (Gly) was used as the plasticizer. Two MC–WP films were formulated. For Group I films, the mass ratio of WP : Gly was constant, whereas for Group II films the mass ratio of polymer (MC + WP) : Gly was constant. The WVP of MC–Gly film decreased with increasing MC concentration, while the tensile strength (TS) and percent elongation (E) increased. The WVP of Group I and Group II films decreased erratically and TS increased when the MC concentration was increased. Group I films had higher TS values than Group II films at the same MC : WP ratios. E of both groups increased with increasing MC concentration (p < 0.05), excluding the films with the highest MC : WP ratio tested (0.8) in Group I films. Group I films had lower E values than Group II films at the same MC : WP ratios. MC effectively governed WVP, TS and E of the WP films. Generally, MC–WP films of this work showed lower WVP than that of MC‐ and WP‐based edible films in the literature. This can potentially make MC–WP films a suitable film material for moisture‐sensitive food products. Copyright © 2005 John Wiley & Sons, Ltd.
A new recycling method for expanded polystyrene
Authors: Shin C.
Published: September 2005

A new recycling method was investigated in this work, in which polystyrene (PS) sub‐µm fibres were electrospun from recycled expanded polystyrene (EPS). The experimental results in this work show that fibres with diameters of around 500 nm were produced by the electrospinning method. The fibres were produced to form a non‐woven mat. Non‐woven mats of electrospun fibres have large surface areas and small pore sizes compared to commercial textiles, making them excellent materials for use in filtration applications. Copyright © 2005 John Wiley & Sons, Ltd.
A QSAR Study of the Brain/Blood Partition Coefficients on the Basis of pKa Values
Authors: Zhang Huabei
Published: September 2005

A database including histamine receptor antagonists and agonists and neutral compounds, physicochemical properties and the equilibrium brain/blood concentration ratios (logBB) were analysed by using linear regression. The correlation between logBB and physicochemical properties has been remarkably improved by grouping the compounds according to their pKa values. For compounds with pKa≥8.5 logBB increases with the maximum atomic positive charge, polarity characterized by the sum of substructural partial charges and decreases with the maximum H‐bond acceptor and the H‐bond donor (n=16, r2=0.864, s=0.316, Q2=0.783). For compounds with a pKa in the range of 6.8≤pKa<8.5 logBB increases with molecular size/bulk (polarizability α) and decreases with polarity and the H‐bond acceptor (n=11, r2=0.892, s=0.246, Q=0.652). For compounds with pKa<6.8 and neutral compounds logBB increases with polarizability and and decreases with the H‐bond acceptor (n=28, r2=0.869, s=0.162, Q2=0.820). logBB of the compounds with high pKa can be also described by logP defined as the difference between logP values measured in 1‐octanol water and those measured in alkane water well, whilst logBB of the neutral compounds and the compounds with low pKa values can be also described by logP(1‐octanol/water) very well, and it seems to be neither logP nor logP can describe logBB of the compounds with intermediate pKa values. These show that the compounds in three groups have different interaction mechanism in brain.
Theoretical study of molecular conduction: I. Effective Green's function based on perturbation theory
Authors: Shimazaki Tomomi , Yamashita Koichi
Published: September 2005

There have been many experimental and theoretical studies on molecular conduction, as it is a fundamental parameter in the study of molecular‐scale electronics. We have investigated the features of molecular conduction using a Green's function method, which has often been used to solve problems in quantum transport and is also effective in elucidating electron transport in molecules. We have obtained the novel effective Green's functions, including the first‐order energy corrections, by accommodating the self‐energy of the electrodes as perturbation terms. Although these approximate Green's functions only provide information on the first‐order energy corrections, they can involve the elementary properties of molecular conduction. We propose a scheme for the analysis of the relations between molecular orbitals and their roles in molecular conduction and present analytical calculations for normal and cyclic polyenes. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Theoretical studies of structural and electronic properties of AlnAsn clusters
Authors: Goswami Biplab , Ghosh Chanchal , Pal Sougata , Sarkar Pranab
Published: September 2005

We present theoretical results of size dependent structural, electronic, and optical properties of ligand‐free stoichiometric AlnAsn clusters of zinc‐blende modification. The investigation is done using a simplified parametrized linear combination of atomic orbital–density functional theory‐local density approximation–tight‐binding (LCAO–DFT–LDA–TB) method and consider clusters with n up to around 100. Initial structures have assumed as spherical parts of infinite zinc‐blende structure and then allowed to relax to the closest local‐energy‐minimum structure. We analyze the radial distributions of atoms, Mulliken populations, electronic energy levels (in particular, HOMO and LUMO), bandgap, and stability as a function of size and composition. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Semiparametric inferences for association with semi‐competing risks data
Authors: Ghosh Debashis
Published: September 2005

In many biomedical studies, it is of interest to assess dependence between bivariate failure time data. We focus here on a special type of such data, referred to as semi‐competing risks data. In this article, we develop methods for making inferences regarding dependence of semi‐competing risks data across strata of a discrete covariateZ. A class of rank statistics for testing constancy of association across strata are proposed; its asymptotic properties are also derived. We develop a novel resampling‐based technique for calculating the variances of the proposed test statistics. In addition, we develop methods for combining test statistics for assessing marginal effects ofZon the dependent censoring variable as well as its effects on association. The finite‐sample properties of the proposed methodology are assessed using simulation studies, and they are applied to data from a leukaemia transplantation study. Copyright © 2005 John Wiley & Sons, Ltd.
Comparing Knowledge of β‐Thalassemia in Samples of Italians, Italian‐Americans, and Non‐Italian‐Americans
Authors: Armeli Christina , Robbins Steven J. , Eunpu Deborah
Published: September 2005

The purpose of this study was to determine the level of β‐thalassemia awareness among Italians living on the eastern side of Sicily (Bronte, Catania, and Tortorici, Messina), Italian‐Americans, and Americans of other ethnic backgrounds (Other‐Americans). A questionnaire was developed which asked respondents knowledge questions about both β‐thalassemia and Down Syndrome. Five hundred questionnaires were distributed, and 456 were ultimately returned and analyzed (150 Italians, 156 Italian‐Americans, 150 Other‐Americans). Italians answered an average of 55% of the β‐thalassemia correctly compared to scores of 17 and 24% for the Italian‐Americans and Other‐Americans, respectively. The groups did not differ in their knowledge of Down Syndrome (all answered between 58 and 60% of the questions correctly on average). Over 80% of the Italian respondents had heard of β‐thalassemia compared to only 19% of the Italian‐Americans. β‐Thalassemia education programs in Italy appear to have dramatically increased awareness of the disorder. Similar programs need to be developed for at‐risk populations in the United States.
Schizophrenia: An Update and Review
Authors: Austin Jehannine
Published: September 2005

Schizophrenia is a common complex disorder characterized by psychosis, cognitive dysfunction and negative symptoms, whose etiology involves interactions between both genetic and environmental vulnerability factors. Recently, ongoing research attempting to elucidate the nature of these vulnerability factors has been generating exciting findings. The advances in understanding of environmental risk factors for mental illnesses and in genetic research into mental illnesses will be reviewed. Limitations of the findings and implications of these advances for genetic counseling practice will also be discussed.
Factors Influencing Uptake of Genetic Testing For Colorectal Cancer Risk in an Australian Jewish Population
Authors: Warner B. J. , Curnow L. J. , Polglase A. L. , Debinski H. S.
Published: September 2005

There is a significant excess of colorectal cancer in the Australian Ashkenazi Jewish community. This excess can partially be attributed to inherited factors that are over represented in this population, such as the APC variant I1307K, which is associated with a modest increase in colorectal cancer risk. There is currently only sporadic clinical genetic testing offered for this variant, as neither the exact increase in cancer risk and therefore the appropriate screening strategies for I1307K carriers, nor the acceptability of such testing in Jewish communities have been determined. This study reports a high acceptability of such genetic testing within a community sample of 300 Australian Jewish individuals—94% of participants would have a test for predisposition to colorectal cancer and a majority would make this decision based on the desire for information for their families and to decrease their own cancer risk. Some concerns were noted about genetic testing for cancer predisposition, including insurance discrimination, test accuracy and confidentiality.
How species diversity responds to different kinds of human‐caused habitat destruction
Authors: Lin Zhenshan , Liu Huiyu
Published: September 2005

Human‐caused habitat destruction, the major cause of species diversity losses, can be classified into two basic types, instantaneous destruction and continuous destruction. Thus, a universal model should be established to simulate and forecast the effects of different kinds of habitat destruction on species diversity during different historical periods. In this paper, we explore a multi‐time‐scale n‐species model to study and compare species responses to instantaneous and continuous destruction. We find that (1) under instantaneous destruction, there are two different mechanisms of species extinction: one is a time‐delayed deterministic extinction of superior competitors in order from the best to the poorest; the other is the extinction in a short time of inferior competitors. The survivors will experience three phases: decline, adjustment, and equilibrium. (2) When the total amounts of habitat destruction for both instantaneous and continuous cases are equal, the oscillation amplitudes of species abundances under instantaneous destruction are much greater than under continuous destruction, especially for inferior competitors, which make inferior competitors under instantaneous destruction more prone to stochastic extinction. Therefore instantaneous destruction is more detrimental to the survival of inferior competitors. (3) Under continuous destruction with habitat eventually being destroyed completely, there also are two types of species extinction mechanisms: the first is extinction in order from the best competitors to the poorest before complete destruction; the second is collective extinction due to complete destruction.