bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface modification on nanoscale titanium dioxide by radiation: Preparation and characterization
Authors: Jiang Bo , Zu Xiaotao , Tang Fangyuan , Wu Zhihong , Lu Jian , Wei Qingrong , Zhang Xingdong
Published: March 2006

Electron beam mutual radiation to induce graft polymerization has been carried out respectively, between nanoscale anatase‐ or rutile‐titanium dioxide particles surface and methyl methacrylate (MMA). The composition and properties of surface modified titanium dioxide were investigated by a number of surface sensitive techniques: X‐ray photoelectron spectrum (XPS), FTIR, X‐ray diffraction (XRD), and NMR. Results of the technological measurements show how surface chemistry is affected throughout the surface modification process, finally leading to a complete and homogeneous vinyl compound overlayer on top of the titanium dioxide samples. In comparison with stereochemical structures of the graft molecular chains and the PMMA induced by radiation polymerization, the surfaces of the oxides are considered to provide a template for the graft polymerization. The grafted titanium dioxide is found to produce a stable colloidal dispersion, in good solvents for the grafted polymer, and the dispersibility of grafted dioxides is influenced by temperature. In addition, the wettability of the surface of titanium dioxide to water is readily controlled by grafting of hydrophilic or hydrophobic polymers. Based on the above results, it is concluded that MMA is covalently linked to the surface of titanium dioxide by a surface modification process. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci, 100: 3510–3518, 2006
Microstructural and mold resistant properties of environment‐friendly oil‐modified polyurethane based wood‐finish products containing polymerized whey proteins
Authors: Wright Nareen C. , Li Jiancai , Guo Mingruo
Published: March 2006

Environmental concerns associated with the level of volatile organic compounds used in surface coatings have stimulated increased scientific research toward novel methods of developing environment‐friendly coatings. Prototype wood finish products containing polymerized whey proteins (PWP) were formulated. The microstructural characteristics of dry films prepared from environment‐friendly wood finishes containing PWP were examined using atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). The susceptibility of the coatings to microbial degradation was also examined using an accelerated mold test. AFM analysis revealed that increased addition of PWP resulted in films with increased surface roughness, decreased number of voids, and increased void size due to excessive aggregation among polymer components. CLSM analysis showed that the PWP distribution in the films is enhanced by homogenization of the coating mixes. There was no significant increase (P > 0.05) in mold growth between panels coated with finish containing PWP and those without PWP. Test panels coated with formulation containing PWP and low levels of biocide (0.3%) resulted in a significant decrease in mold growth in comparison to commercially available water‐based polyurethane coatings (P < 0.05). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3519–3530, 2006
The influence of alkali pretreatments in lyocell resin finishing—Resin distribution and mechanical properties
Authors: Manian Avinash P. , Rous Mohammad Abu , Schuster K. Christian , Bechtold Thomas
Published: March 2006

Lyocell fabric samples were pretreated with NaOH and KOH and resin finished. The treated samples were tested to determine the influence of alkali pretreatments on the tenacity, abrasion resistance, and crease recovery of resin‐finished lyocell. Alkali pretreatments resulted in a higher surface concentration of the crosslinking reagent in fabrics, leading to lowered crease recovery and abrasion resistance. The pretreatments also exerted a deleterious influence on the tensile strength in resin‐finished samples. However, the differential distribution of crosslinking reagent within the textile structure does not appear to be the only factor responsible for the changes observed in substrate properties; other factors also appear to be responsible for the results observed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3596–3601, 2006
Synthesis and characterization of p‐perfluoro{1‐[2‐(2‐fluorosulfonyl‐ethoxy)propoxy]}ethylated poly(α‐methyl styrene)
Authors: Ni Hong‐Bo , Yang Ji‐Cheng , Zhao Cheng‐Xue
Published: March 2006

p‐Perfluoro{1‐[2‐(2‐fluorosulfonyl‐ethoxy)propoxy]}ethylated poly(α‐ methyl styrene) 3 was synthesized via electron transfer of perfluoro‐di{2‐[2‐(2‐fluorosulfonyl‐ethoxy)propoxy]}propionyl peroxide 2 and poly(α‐methyl styrene) 1 at different reactant molar ratios (2 : 1). The modified polymer 3 was characterized by various techniques. The ring p‐substitution was proved by FTIR and 19FNMR. The desulfonation appeared at above 124°C was found by TGA. The molecular weight determined by GPC increased with the increase of reactant molar ratio, and the polydispersity values indicated there was no degradation of the parent polymer chain in the reaction. Followed by hydrolysis and acidification, the modified polymer 3 could be further quantitatively converted into its sulfonic form 4. Ion exchange capacity of novel polyelectrolyte 4 can be controlled by changing reactant molar ratio (2 : 1). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3615–3618, 2006
Proton conducting blends based on polysulfones and elastomers
Authors: Linares A. , Acosta J. L. , Rodríguez S.
Published: March 2006

With the aim of improving the performance of conventional proton conducting membranes, systems based on two poly(arylene ether sulfone)s and two elastomers were obtained by heterogeneous sulfonation with chlorosulfonic acid. Subsequently, they were characterized, morphologically and electrically, by techniques such as infrared spectroscopy (FTIR), differential scanning calorimetry, dynamic‐mechanical analysis, and complex impedance spectroscopy. From the results, it was verified that the reaction of sulfonation had taken place, as well as that these materials formed incompatible and good proton conducting blends. In addition, the storage modulus and the conductivity were subjected to a statistical design to predict the optimum composition, presenting the best mechanical and conducting proton values and as a consequence the most suitable membrane from the point of view of its application in the field of the fuel cells. Very promising results have been found especially with membranes based on binary blends constituted by thermoplastic/elastomer polymers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3474–3482, 2006
Novel nitrogen‐containing epoxy resin. II. Cure kinetics by differential scanning calorimetry
Authors: Hong Zhang Xing , Qin Min Yu , Zhao Hui , Mei Wan Hong , Rong Qi Guo
Published: March 2006

The isothermal and nonisothermal cure behaviors of a novel nitrogen‐containing epoxy resin (XT resin) were studied by differential scanning calorimetry (DSC). Various kinetic parameters and details of cure process were obtained based on the Avrami theory. The results indicated that Avrami method is suitable for calculating the kinetic parameters up to the gel point at least. The apparent activation energy (Ea) for isothermal cure process was in agreement with that for nonisothermal cure process. Ea value in the early stage (78.5–81.0 KJ mol−1) was about three times than that in the later stage (23.3–26.5 KJ mol−1). The kinetic results from Avrami theory may present a combined effect of all factors, and which is helpful to understand the cure technique for XT–DDS system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3483–3489, 2006
Effect of water absorption, freezing and thawing, and photo‐aging on flexural properties of extruded HDPE/rice husk composites
Authors: Panthapulakkal S. , Law S. , Sain M.
Published: March 2006

Durability of lingo‐cellulosic fiber composites under environmental conditions such as moisture, freezing and thawing, and UV exposure needs to be determined prior to the use of these composite materials in outdoor applications. Dimensional stability and changes in the flexural strength and stiffness of extruded rice husk filled high‐density polyethylene composites with and without processing additives such as compatibilizers and processing aid were examined after exposing the composites to water, conditions of freeze–thaw cycles, and UV light. Water absorption results indicated a decrease in the rate of penetration of water in the composites in the presence of compatibilizers. The reduction in strength and stiffness after water absorption was lower for composites with compatibilizers than for the composites without any additives. Freezing and thawing experiments also showed the dimensional changes and degradation of strength and stiffness were less in composites with compatibilizers. Presence of processing aid in the composite showed a similar or enhanced water absorption and loss of mechanical properties, compared with those of the composite without processing additives. Although the composites showed a discoloration of the surface after the UV exposure time (745 h) studied, it was found that within this period of UV exposure the flexural strength and stiffness of the composites did not show significant change. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3619–3625, 2006
Electrochemistry of methanofullerene films: Simultaneous cyclic voltammetry and electrochemical quartz crystal microbalance studies
Authors: Zhang H. , Huang X. , Fan L. Z. , Nin B. , Wu Y. Q. , Zheng L. P. , Cao Y.
Published: March 2006

Electrochemical properties of eight methanofullerene films, prepared on electrodes by casting, were examined by means of cyclic voltammetry and electrochemical quartz crystal microbalance (EQCM) technique in acetonitrile solution. Compared with C60 film, the film stability with respect to dissolution is associated with the length of the alkyl chains introduced into C60 cage and is strongly dependent on the nature of the cation of the supporting electrolyte. TBA+, Li+, K+, and Na+ were selected to observe the effect of countercations on the electrochemical behavior of methanofullerene films. In TBAPF6 solution, when short chains, such as formic ether or butyl butyrate groups, were introduced into C60 cage, the film stability was less than that of C60. When the length of the alkyl chain was extended to butyl 12 alkanoate group, the film would not dissolve until the third reduction process because the long alkyl chain could inflect and encase the cations into the film. In KPF6 or NaClO4 solution, however, the solubility of the salt formed by K+ or Na+ with methanofullerene anion was higher than that formed by TBA+ with methanofullerene anion. Li+ (alkali metal) affected the behavior of the films in different ways. The possible electron‐transfer mechanisms of methanofullerene films in various supporting electrolyte solutions were presented. Furthermore, the film images observed by atomic force microscopy indicated that TBA+ and Li+ affected the behavior of the methanofullerene films in different ways. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3634–3640, 2006
Effect of modified carbon black on the filler–elastomer interaction and dynamic mechanical properties of SBR vulcanizates
Authors: Han Jingjie , Zhang Xiliang , Guo Weihong , Wu Chifei
Published: March 2006

A new modified carbon black (GCB) was prepared by adding special RFL latex into N220. Dynamic properties were obtained over a wide range of temperatures and strains on vulcanizates filled with GCB and unmodified carbon black, respectively. The results show that the GCB can effectively decrease the tan δ value at 60 and 90°C of SBR vulcanizates compared with that of the common unmodified carbon blacks, which responds to the fact that GCB is beneficial to lower rolling resistance and heat generation of the vulcanizates in comparison to that of the unmodified carbon black. Among the factors responsible for this, filler networking and filler–elastomer interaction play a dominant role. The effects of filler loading on mechanical properties of vulcanizates were also investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3707–3712, 2006
Multicarboxylic aromatic acid core initiator for the synthesis of star‐shaped poly(ϵ‐caprolactone) with carboxyl end groups
Authors: Jia Zhongfan , Huang Junlian
Published: March 2006

We successfully carried out the ring‐opening polymerization of ϵ‐caprolactone with 1,3,5‐benzenetricarboxylic acid and 1,2,4,5‐benzenetetracarboxylic acid as the core initiators at 225°C in bulk, and three‐armed and four‐armed star poly(ϵ‐caprolactone)s [poly(ϵ‐CL)s] with carboxyl end groups were obtained. No transesterification, which would have led to a decrease in the molecular weight of poly(ϵ‐CL), was found. The effects of the polymerization conditions on the polymerization are discussed; the poly(ϵ‐CL)s were characterized by1H‐NMR, gel permeation chromatography, and thermogravimetric analysis in detail. A mechanism of alkyl–oxygen bond scission by the nucleophilic attack of the carboxyl anions via hydrogen proton transfer is presented for this system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3713–3717, 2006
Single‐pack, self‐curable, aqueous‐based polyurethane dispersion containing a disperse dye
Authors: Huang Ching‐Tzer , Chen Kan‐Nan
Published: March 2006

An organic‐solvent‐soluble disperse dye was introduced into an aqueous phase by a reaction with a self‐emulsified, aqueous‐based polyurethane (PU), and this resulted in the formation of a homogeneous, aqueous polymeric dye dispersion. This aqueous polymeric dye was stable in a water phase with excellent color extension upon application. It was formulated with a latent curing agent, polyaziridine (e.g., TMPTA‐AZ), as a single‐component, self‐curable, aqueous polymeric dye. The curing reaction took place between PU carboxylic acid and the latent curing agent upon drying. A self‐cured polymeric dye was obtained with excellent color extension and fastness and resistance to organic solvents and water after drying. This single‐component, self‐curable, aqueous‐based PU system containing a dye has potential for printing, writing, and dyeing applications. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 2006 © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3741–3747, 2006
The measurement of thermal diffusivity in poly(methyl acrylate) by photoacoustic technique
Authors: Rajan M. A. Jothi , Mathavan T. , Vivekanandam T. S. , Umapathy S.
Published: March 2006

It is suggested that when a polymer is synthesized from a monomer and an added initiator in the presence of ultrasound, the process may produce polymers with predetermined structures and physical properties. An attempt is made to measure thermal diffusivity. Poly(methyl acrylate) (PMA) is synthesized using monomer methyl acrylate and an added initiator peroxodisulfate in the presence of ultrasound of frequency 35 kHz and power 100 W/cm2 at 50°C for various known sonication periods. PMA is obtained as a colorless, semitransparent solid. The solid PMA is cut into thin wafers in a highly symmetric direction to have uniform sizes. PMA samples are synthesized for 11 different sonication periods. These PMA samples are use to study their thermal diffusivity (α) by photoacoustic (PA) technique. Thermal diffusivity is calculated by measuring the amplitude and phase of the PA signal separately. A plot of the sonication period versus thermal diffusivity obtained from amplitude measurements of PMA indicates that there is an increase in thermal diffusivity from 2 × 10−6 to 4.7 × 10−6 m2/s when sonication period is increased from 30 to 330 min in steps of 30 min. The same trend is seen in a plot between sonication period and thermal diffusivity when the thermal diffusivity is calculated by PA phase measurements. There is a small difference in the experimental values obtained by the two measurements. Dependence of thermal diffusivity of PMA on ultrasonic sonication is discussed in detail. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 3756–3760, 2006
A theoretical description of the oxidation kinetics of polymer melt in fractal mediums
Authors: Kozlov G. V. , Dolbin I. V. , Zaikov G. E.
Published: March 2006

It is shown that the fractal approach using fractional integration and derivation gives an adequate description of decelerated curves in relation to consumed oxygen—and time. A clear physical interpretation of the fractal exponent as a fractional part of the fractal dimension of a macromolecular coil is obtained. It also indicates that classical equation is a particularly limiting case of the fractal relationship applicable to Euclidean mediums. The initial oxygen amount is represented as a constant in basic fractal relationship, which is also a function of the macromolecular coil structure. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 3761–3764, 2006
Structure and function in the auditory system: From cochlea to cortex
Authors: Friedland David R.
Published: March 2006

This special issue of the Anatomical Record examines the relationship between structure and function in the auditory system. Early anatomical studies defined this relationship on a macroscopic level and described the roles of structures such as the tympanic membrane, ossicular chain, Eustachian tube, and cochlea. As new tools emerged, the microscopic structure of the organ of Corti was described and later the brain stem regions involved in auditory processing were identified. Further technical advances allowed the description of cells within these central auditory regions in both morphological and physiological terms. More recently, studies of the auditory system have employed molecular biological techniques and novel imaging protocols. All these techniques continue to provide important insights into the structure and function of the auditory system on gross, cellular, and molecular levels. This issue expounds on this theme by demonstrating the importance of anatomy, whether the shape of the otic capsule or the sequence of a gene, in determining the function of the system and even the phenotype of the organism. The articles in this issue represent the cutting edge of today's auditory science and look back at the evolution of hearing and balance, as well as forward toward improving cochlear implant outcomes and gene therapies for treating sensorineural hearing loss. Anat Rec Part A, 2006. © 2006 Wiley‐Liss, Inc.
Central auditory pathways mediating the rat middle ear muscle reflexes
Authors: Lee Daniel J. , de Venecia Ronald K. , Guinan John J. , Brown M. Christian
Published: March 2006

The middle ear muscle (MEM) reflexes function to protect the inner ear from intense acoustic stimuli and to reduce acoustic masking. Sound presented to the same side or to the opposite side activates the MEM reflex on both sides. The ascending limbs of these pathways must be the auditory nerve fibers originating in the cochlea and terminating in the cochlear nucleus, the first relay station for all ascending auditory information. The descending limbs project from the motoneurons in the brainstem to the MEMs on both sides, causing their contraction. Although the ascending and descending pathways are well described, the cochlear nucleus interneurons that mediate these reflex pathways have not been identified. In order to localize the MEM reflex interneurons, we developed a physiologically based reflex assay in the rat that can be used to determine the integrity of the reflex pathways after experimental manipulations. This assay monitored the change in tone levels and distortion product otoacoustic emissions within the ear canal in one ear during the presentation of a reflex‐eliciting sound stimulus in the contralateral ear. Preliminary findings using surgical transection and focal lesioning of the auditory brainstem to interrupt the MEM reflexes suggest that MEM reflex interneurons are located in the ventral cochlear nucleus. Anat Rec Part A, 2006. © 2006 Wiley‐Liss, Inc.
Left hemispheric lateralization of brain activity during passive rhythm perception in musicians
Authors: Limb Charles J. , Kemeny Stefan , Ortigoza Eric B. , Rouhani Sherin , Braun Allen R.
Published: March 2006

The nature of hemispheric specialization of brain activity during rhythm processing remains poorly understood. The locus for rhythmic processing has been difficult to identify and there have been several contradictory findings. We therefore used functional magnetic resonance imaging to study passive rhythm perception to investigate the hypotheses that rhythm processing results in left hemispheric lateralization of brain activity and is affected by musical training. Twelve musicians and 12 nonmusicians listened to regular and random rhythmic patterns. Conjunction analysis revealed a shared network of neural structures (bilateral superior temporal areas, left inferior parietal lobule, and right frontal operculum) responsible for rhythm perception independent of musical background. In contrast, random‐effects analysis showed greater left lateralization of brain activity in musicians compared to nonmusicians during regular rhythm perception, particularly within the perisylvian cortices (left frontal operculum, superior temporal gyrus, inferior parietal lobule). These results suggest that musical training leads to the employment of left‐sided perisylvian brain areas, typically active during language comprehension, during passive rhythm perception. Anat Rec Part A, 2006. Published 2006 Wiley‐Liss, Inc.
Axon guidance cues in auditory development
Authors: Webber Audra , Raz Yael
Published: March 2006

The innervation of the cochlear sensory epithelium is intricately organized, allowing the tonotopy established by the auditory hair cells to be maintained along the ascending auditory pathways. These auditory projections are patterned by several gene families that regulate neurite attraction and repulsion, known as axon guidance cues. In this review, the roles of various axon guidance molecules, including fibroblast growth factor, ephs, semaphorins, netrins and slits, are examined in light of their known contribution to auditory development. Additionally, morphogens are discussed in the context of their recently described influence on axonal pathfinding in other sensory systems. The elucidation of these various mechanisms may guide the development of therapies aimed at maximizing the connectivity of auditory neurons in the context of congenital or acquired sensorineural hearing loss, especially as pertains to cochlear implants. Further afield, improved understanding of the molecular processes which regulate innervation of the organ of Corti during normal development may prove useful in connecting regenerated hair cells to the central nervous system. Anat Rec Part A, 2006. © 2006 Wiley‐Liss, Inc.
Projections from auditory cortex to cochlear nucleus: A comparative analysis of rat and mouse
Authors: Meltzer Noah E. , Ryugo David K.
Published: March 2006

Mammalian hearing is a complex special sense that involves detection, localization, and identification of the auditory stimulus. The cerebral cortex may subserve higher auditory processes by providing direct modulatory cortical projections to the auditory brainstem. To support the hypothesis that corticofugal projections are a conserved feature in the mammalian brain, this article reviews features of the rat corticofugal pathway and presents new data supporting the presence of similar projections in the mouse. The mouse auditory cortex was localized with electrophysiological recording and neuronal tracers were injected into AI. The cochlear nucleus was dissected and examined for terminal fibers by light and electron microscopy. Bouton endings were found bilaterally forming synapses with dendrites of granule cells of the cochlear nucleus. This report provides evidence for direct auditory cortex projections to the cochlear nucleus in the mouse. The distribution of projections to the granule cell domain and the synapses onto granule cell dendrites are consistent with what has been reported for rats and guinea pigs. These findings suggest a general plan for corticofugal modulation of ascending auditory information in mammals. Corticobulbar inputs to the auditory brainstem likely provided a survival advantage by improving sound detection and identification, thus allowing the development of complex social behaviors and the navigation of varied environments. Anat Rec Part A, 2006. © 2006 Wiley‐Liss, Inc.
Nicotinic acetylcholine receptor structure and function in the efferent auditory system
Authors: Lustig Lawrence R.
Published: March 2006

This article reviews and presents new data regarding the nicotinic acetylcholine receptor subunits α9 and α10. Although phylogentically ancient, these subunits have only recently been identified as critical components of the efferent auditory system and medial olivocochlear pathway. This pathway is important in auditory processing by modulating outer hair cell function to broadly tune the cochlea and improve signal detection in noise. Pharmacologic properties of the functionally expressed α9α10 receptor closely resemble the cholinergic response of outer hair cells. Molecular, immunohistochemical, and knockout mice studies have added further weight to the role this receptor plays in mediating the efferent auditory response. Alternate and complementary mechanisms of outer hair cell efferent activity might also be mediated through the nAChR α9α10, either through secondary calcium stores, second messengers, or direct protein‐protein interactions. We investigated protein‐protein interactions using a yeast‐two‐hybrid screen of the nAChR α10 intracellular loop against a rat cochlear cDNA library. Among the identified proteins was prosaposin, a precursor of saposins, which have been shown to act as neurotrophic factors in culture, can bind to a putative G0‐coupled cell surface receptor, and may be involved in the prevention of cell death. This study and review suggest that nAChR α9α10 may represent a potential therapeutic target for a variety of ear disorders, including preventing or treating noise‐induced hearing loss, or such debilitating disorders as vertigo or tinnitus. Anat Rec Part A, 2006. © 2006 Wiley‐Liss, Inc.
Cochlear implantation trauma and noise‐induced hearing loss: Apoptosis and therapeutic strategies
Authors: Eshraghi Adrien A. , Van De Water Thomas R.
Published: March 2006

Cochlear implantation trauma and noise‐induced hearing loss both involve a physical disruption of the organ of Corti and may involve several mechanisms of cell death at the molecular level, i.e., necrosis, necrosis‐like programmed cell death (PCD; type 2 PCD), and apoptosis (type 1 PCD). This article reviews several promising therapeutic strategies that are currently being developed. One of these promising new strategies involves the use of a highly effective peptide inhibitor of the c‐Jun N‐terminal kinase cell death signal cascade (i.e., D‐JNKI‐1) to prevent apoptosis of injured auditory hair cells. Our recent studies showed prevention of cochlear implantation‐induced hearing loss by infusing this peptide into the cochlea of guinea pigs. Another otoprotective therapy under investigation is the application of mild hypothermia to protect the cochlea from the development of a hearing loss that follows exposure to a physical trauma, e.g., electrode array insertional trauma. These forward‐looking strategies have the potential of improving hearing outcomes after cochlear implantation and providing novel means of otoprotection from noise‐induced trauma. Anat Rec Part A, 2006. © 2006 Wiley‐Liss, Inc.
Planning and Analyzing Adaptive Group Sequential Survival Trials
Authors: Wassmer Gernot
Published: March 2006

The use of adaptive methods has experienced increasing interest in the current literature on group sequential designs. Group sequential analysis in survival trials usually apply the error spending function approach due to the unpredictable amount of information available in an interim analysis. An alternative way is to apply adaptive methods where additionally the maximum amount of information and other designing parameters can be changed based on the information available at the interim stage. In this paper, it is shown how the inverse normal method can be used within a survival design using the log‐rank test for comparing two survival functions. This method allows for many kinds of design modifications. In case of no modifications, the inverse normal method coincides with the commonly used analysis strategy.

It is straightforward to specify effect estimates. Confidence intervals for the hazard ratio that can be calculated at each stage of the trial and intervals that can only be computed by the end of the trial are proposed. The latter also enables the calculation of median unbiased estimates. Overallp‐values can be defined analogously. Properties of the analyses techniques are investigated and compared with alternative approaches. It is shown that the proposed analysis technique might help to rescue an underpowered study and opens the way to other types of changes in design. The proposed technique is implemented in the software ADDPLAN Adaptive Design, Plans and Analyses (http://www.addplan.com). (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Two‐step protocol to incorporate cells in thermoresponsive hydrogels
Authors: Sawant Prashant D. , Achuth Hosur N. , Moochhala Shabbir M.
Published: March 2006

One of the stumbling blocks in the formation of a thermoresponsive cell‐hydrogel hybrid (TCH) is the efficient incorporation of cells in thermoresponsive hydrogels (TH) using traditional top‐down (i.e., cells penetrate in the pre‐set gels from top surface) approach. This approach is slow and tedious because the hydrogel needs to soak in the cells culture for a long time to allow cells to penetrate from the gel surface in to the bulk of the gel. In addition, cell incorporation into TH is difficult because elevated dissolution temperatures of gelators are detrimental to cell viability, whereas the highly viscous gel state that formed at ambient temperatures retards the penetration of cells. We propose a bottom‐up approach (i.e., cells mixed prior to gel setting) using a novel two‐step protocol. The first step is the rapid cooling of the agarose solution from its dissolution temperature (98°C) to 37°C and equilibrating for 3–4 min. The second step is the mixing of fibroblasts with the agarose solution and natural cooling to the room temperature to form the TCH. With this novel protocol, 90% of fibroblasts are found to be trapped in the cell‐gel hybrid.
Effect of molecular crowding on DNA polymerase activity
Authors: Sasaki Yoshiharu , Miyoshi Daisuke , Sugimoto Naoki
Published: March 2006

Live cells contain high concentrations of macromolecules, but almost all experimental biochemical data have been generated from dilute solutions that do not reflect conditions in vivo. To understand biomolecular behavior in vivo, properties studied in vitro are extrapolated to conditions in vivo; however, the molecular conditions within live cells are inherently crowded. The present study investigates the effect of molecular crowding on DNA polymerase activity using polyethylene glycol PEG of various molecular weights as a crowding agent. Polymerase activity assays under various conditions demonstrated that the activities of T7 and Taq DNA polymerases depend on the molecular weight and concentration of the crowding agent. Furthermore, equilibrium and kinetic analyses demonstrated that the binding affinity and catalytic activity of the polymerase increase and decrease, respectively, with increasing PEG concentrations. Based on quantitative parameters of the polymerase reactions, we improved the efficiency of PCR amplification under conditions of molecular crowding. These results suggest that quantitative measurements of biomolecular structure and function are useful for understanding the behavior of biomolecules in vivo and for biotechnology applications in vitro.
Sequence quality is maintained after multiple displacement amplification of non‐invasively obtained macaque semen DNA
Authors: Andrés Olga , Rönn Ann‐Charlotte , Ferrando Aïnhoa , Bosch Montserrat , Domingo‐Roura Xavier
Published: March 2006

Whole genome amplification protocols are revolutionizing the fields of molecular and conservation biology as they open the possibility of obtaining a large number of copies of a complete genome from minute amounts of sample. Multiple displacement amplification (MDA) is a whole genome amplification technique based on the properties of the phi29 DNA polymerase, which leads to a uniform representation of the genome with very low error rates. In this study we performed MDA on 28 macaque DNA samples extracted from blood or non‐invasively collected semen from which we obtained mitochondrial control region sequences both before and after MDA. The length of the readable sequences was longer for the original samples than for the MDA products, but the number of unresolved positions was comparable both before and after MDA. We conclude that the MDA technique is useful for increasing the amount of DNA for sequencing mitochondrial regions in the case of non‐invasively collected semen samples.
Long‐term efficacy of transcatheter patent foramen ovale closure on migraine headache with aura and recurrent stroke
Authors: Giardini Alessandro , Donti Andrea , Formigari Roberto , Salomone Luisa , Palareti Gualtiero , Guidetti Donata , Picchio Fernando Maria
Published: March 2006

Objectives: To assess the long‐term results of transcatheter patent foramen ovale (PFO) closure on migraine headache with aura (MHA) and on the risk of recurrent stroke. Background: Transcatheter PFO closure is associated with an early improvement of MHA, and a reduction or the risk of recurrent cerebral ischemia, but the long‐term outcome after the procedure is unknown. Methods: We analyzed follow‐up data of 38 consecutive patients who had undergone transcatheter PFO closure at our institution because of cryptogenic stroke and had been followed‐up for at least 3 years after the procedure. Mean age at closure was 43 ± 13 years. Thirteen patients (34%) had a diagnosis of MHA made by the primary care physician or the referring neurologist. Migraine disability assessment questionnaire (MIDAS) was used to assess MHA incidence and severity. Results: After a mean follow‐up of 4.8 ± 1.4 years, two patients had a recurrent stroke (13 and 15 months after the procedure, respectively). Recurrence rate 5 years after the procedure was 5.3%. After 4.9 ± 1.4 years from the intervention, 12/13 patients (92%, 95% CI 65–99%) had complete resolution in their MHA. Overall, MIDAS score decreased significantly (38.6 ± 26.3 vs. 4.4 ± 5.1, P < 0.0001) after the procedure. One patient did not report any improvement of MHA after transcatheter PFO closure, whereas one patient reported a severe relapse of MHA about 1 year after PFO closure. Freedom from recurrent MHA 5 years after the procedure was 85% (95% CI 57–97%). Conclusions: The rate of recurrent cerebral ischemia and recurrent MHA seems to be low at long‐term follow‐up after transcatheter PFO closure. Recurrent cerebral ischemia and relapse of MHA seem to be confined to the first 15 months after the procedure.© 2006 Wiley‐Liss, Inc.
Transcatheter device versus surgical closure of ventricular septal defects: A clinical decision analysis
Authors: Aleem Ilyas S. , Karamlou Tara , Benson Lee N. , McCrindle Brian W.
Published: March 2006

Objectives: To compare transcatheter device versus surgical closure of ventricular septal defects (VSDs). Methods: A clinical decision analysis was performed using standard gamble interviews. Results: Device was initially preferred in 39 respondents (89%) and surgery in 5 (11%). The inherent difference in value between a perfect surgery and a perfect device (disutility of surgery) was equal to a mean risk of death of (1.2 ± 2.2)%. Final values from decision analysis were initially equivalent. Values adjusted for estimated mortality, however, favored device (mean: 0.979 ± 0.032) versus surgery (mean: 0.971 ± 0.032), P = 0.052. When values were further adjusted for disutilities, device was significantly preferred (0.978 ± 0.032) versus surgery (0.961 ± 0.044), P < 0.005. Surgery would be preferred if the probability of major complications decreased below 5% or minor complications below 6%. Conclusions: When outcomes and their values are considered in a systematic manner, transcatheter device closure of suitable VSDs is favored over surgical repair. © 2006 Wiley‐Liss, Inc.
Electron Transfer in Supercritical Carbon Dioxide: Ultraexothermic Charge Recombination at the End of the “Inverted Region”
Authors: Serpa Carlos , Gomes Paulo J. S. , Arnaut Luis G. , Formosinho Sebastião J. , Pina João , de Melo J. Seixas
Published: March 2006

Charge‐recombination rates in contact radical‐ion pairs, formed between aromatic hydrocarbons and nitriles in supercritical CO2 and heptane, decrease with the exothermicity of the reactions until they reach −70 kcal mol−1, but from there on an increase is observed. The first decrease in rate is typical of the “inverted region” of electron‐transfer reactions. The change to an increase in the rate for ultra‐exothermic electron transfer indicates a new free‐energy relationship. We show that the resulting “double‐inverted region” is not due to a change in mechanism. It is an intrinsic property of electron‐transfer reactions, and it is due to the increase of the reorganisation energy with the reaction exothermicity.
π‐Conjugated Chelating Polymers with Charged Iridium Complexes in the Backbones: Synthesis, Characterization, Energy Transfer, and Electrochemical Properties
Authors: Liu Shu‐Juan , Zhao Qiang , Chen Run‐Feng , Deng Yun , Fan Qu‐Li , Li Fu‐You , Wang Lian‐Hui , Huang Chun‐Hui , Huang Wei
Published: March 2006

A series of π‐conjugated chelating polymers with charged iridium (Ir) complexes in the backbones were synthesized by a Suzuki polycondensation reaction, leading to homogeneous polymeric materials that phosphoresce red light. The fluorene and bipyridine (bpy) segments were used as polymer backbones. 5,5′‐Dibromobipyridine served as a ligand to form a charged iridium complex monomer with 1‐(9′9‐dioctylfluorene‐2‐yl)isoquinoline (Fiq) as the cyclometalated ligand. Chemical and photophysical characterization confirmed that Ir complexes were incorporated into the backbones as one of the repeat units by means of the 5,5′‐dibromobipyridine ligand. Chelating polymers showed almost complete energy transfer from the host fluorene segments to the guest Ir complexes in the solid state when the feed ratio was 2 mol %. In the films of the corresponding blend system, however, energy transfer was not complete even when the content of Ir complexes was as high as 16 mol %. Both intra‐ and intermolecular energy‐transfer processes existed in this host–guest system, and the intramolecular energy transfer was a more efficient process. All chelating polymers displayed good thermal stability, redox reversibility, and film formation. These chelating polymers also showed more efficient energy transfer than the corresponding blended system and the mechanism of incorporation of the charged Ir complexes into the π‐conjugated polymer backbones efficiently avoided the intrinsic problems associated with the blend system, thus offering promise in optoelectronic applications.
Regio‐ and Diastereoselective Synthesis of Bis‐ and Tetrakisadducts of C70 by Directed Remote Functionalization Using Tröger Base Tethers
Authors: Wong Wallace W. H. , Diederich François
Published: March 2006

Double Bingel cyclopropanation of C70 with bismalonates featuring Tröger base derivatives as chiral spacers afforded bisadducts with almost perfect regio‐ and stereoselectivity. The excellent directing property of these rigidly folded spacers in the remote functionalization of the higher fullerene was further highlighted by the selective formation of a product with a novel bisaddition pattern involving the C(7)C(22) and C(33)C(34) bonds of C70. Enantiomerically pure bisadducts of C70 were prepared by highly diastereoselective transformations of bismalonates incorporating optically pure Tröger base tethers. The absolute configuration of these bisadducts was established by comparison of circular dichroism (CD) spectra with data reported in the literature. For the first time, optically active tetrakisadducts of a fullerene were prepared by two sequential chiral‐spacer‐controlled remote functionalizations.
Hydrogen‐Bonded Self‐Assembly of Pyridinium and Anilinium Bisphenols Mediated by the Hydrogen Difluoride Ion: Towards Control of CH⋅⋅⋅π (Aromatic) Interactions
Authors: Sarma Rupam J. , Baruah Jubaraj B.
Published: March 2006

The role of CH⋅⋅⋅π and CH⋅⋅⋅O interactions in HF2−‐assisted self‐assembly of nitrogen‐containing bisphenols are investigated. Unusual control on the end–face and edge–face geometries of aromatic CH⋅⋅⋅π interactions by a water molecule in the 4‐[(4‐hydroxy‐3,5‐dimethylphenyl)methyl]pyridinium difluoride lattice is observed. The bis(4‐hydroxy‐3,5‐dimethylphenyl)(4‐ammoniophenyl)methane⋅HF2− self‐assembles through the formation of hydrogen‐bonded cyclic hexamers.
Efficient Synthesis of a Chiral [4]Pseudocatenane and Its Derivatives: A Novel Ship's Wheel‐like Interlocked Structure
Authors: Zhu Xiao‐Zhang , Chen Chuan‐Feng
Published: March 2006

A novel chiral[4]pseudocatenane 5H3[PF6]3 was synthesized efficiently by treatment of a solution of chiral triptycene‐based tri(crown ether) 1 and three equivalents of a bis[p‐(but‐3‐enyloxy)benzyl]ammonium salt in CH2Cl2 with a Grubbs II catalyst, followed by hydrogenation. It was found that the ammonium groups in 5H3[PF6]3 could be deprotonated by 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) in acetonitrile or dimethyl sulfoxide (DMSO). Consequently, N‐acylation of the ammonium groups was easily performed in the presence of DBU, which resulted in a new class of neutral highly ordered interlocked molecules in good yields. In particular, the incorporation of stopper units, for example, diethyl phosphoramidate, lead to the isolation of the interlocked molecule 10 with an interesting ship's wheel‐like structure, which was structurally studied with the help of detailed NMR experiments. Compared with 1, it was further found that the Cotton effect of (R)‐1,1′‐binaphthyl chromophore at 241 nm was greatly reduced in 5H3[PF6]3 and its derivatives. Moreover, a new positive Cotton effect at 248 nm appeared in the interlocked molecules; this observation could be attributed to the chirality transfer from the binaphthyl units to the macrocycles lying in the cavities of 1.
Knockout of KASIII regulation changes fatty acid composition in canola (Brassica napus)
Authors: Stoll Christof , Lühs Wilfried , Zarhloul M. Karim , Brummel Monika , Spener Friedrich , Friedt Wolfgang
Published: March 2006

In contrast to the dominating unsaturated C18 fatty acid, medium‐chain fatty acids (MCFA) are nearly absent in the oil of common canola. Modification of canola oil towards higher contents of C8 to C14 fatty acids would create new possibilities for oleo‐chemical usages, in both the nutritional and the non‐food sectors. For this purpose, spring oilseed rape (cv. ‘Drakkar’) was genetically modified by introduction of MCFA‐encoding genes from Cuphea species containing approximately 90% MCFA in their seed oil. Two different single constructs involving the 3‐ketoacyl‐acyl carrier protein synthase (KAS)III from C. lanceolata were used, one harbouring the wild‐type gene, ClKASIIIbwt, and the other containing the point‐mutated gene, ClKASIIIbmut, along with two double constructs containing ClKASIIIbmut in combination with a medium‐chain thioesterase gene from C. lanceolata (ClFatB3) or C. hookeriana (ChFatB2). For both single‐gene constructs, a phenotype with an increased content of MCFA was not detected; however, the ClKASIIIbwt transformants produced up to 6.7% palmitic acid (C16). In T2 seeds bearing the ClKASIIIbmut/ClFatB3 double‐gene construct, contents of up to 2.9% capric (C10) and 11.4% palmitic acid were achieved. The best transformant with the gene construct ClKASIIIbmut/ChFatB2 contained 1.4% caprylic acid (C8) and 7.9% C10, and these results were confirmed in T3 seeds.
Alterations of the mitochondrial proteome caused by the absence of mitochondrial DNA: A proteomic view
Authors: Chevallet Mireille , Lescuyer Pierre , Diemer Hélène , van Dorsselaer Alain , Leize‐Wagner Emmanuelle , Rabilloud Thierry
Published: March 2006

The proper functioning of mitochondria requires that both the mitochondrial and the nuclear genome are functional. To investigate the importance of the mitochondrial genome, which encodes only 13 subunits of the respiratory complexes, the mitochondrial rRNAs and a few tRNAs, we performed a comparative study on the 143B cell line and on its Rho‐0 counterpart, i.e., devoid of mitochondrial DNA. Quantitative differences were found, of course in the respiratory complexes subunits, but also in the mitochondrial translation apparatus, mainly mitochondrial ribosomal proteins, and in the ion and protein import system, i.e., including membrane proteins. Various mitochondrial metabolic processes were also altered, especially electron transfer proteins and some dehydrogenases, but quite often on a few proteins for each pathway. This study also showed variations in some hypothetical or poorly characterized proteins, suggesting a mitochondrial localization for these proteins. Examples include a stomatin‐like protein and a protein sharing homologies with bacterial proteins implicated in tyrosine catabolism. Proteins involved in apoptosis control are also found modulated in Rho‐0 mitochondria.
A proteomic approach to investigate potential biomarkers directed against membrane‐associated breast cancer proteins
Authors: Canelle Ludovic , Bousquet Jordane , Pionneau Cedric , Hardouin Julie , Choquet‐Kastylevsky Genevieve , Joubert‐Caron Raymonde , Caron Michel
Published: March 2006

The identification of specific protein markers for breast cancer would provide the basis for early diagnosis. Particularly, membrane and membrane‐associated proteins are rich in targets for antibodies that may constitute suitable biomarkers of carcinogenesis. However, membrane proteins separation using 2‐DE remains difficult. In this work, the breast cancer cell line MCF7 was used as source of proteins for the screening of potential cell membrane‐associated antigens recognized by autoantibodies in patients with breast cancer and healthy volunteers. The protein extract obtained using trifluoroethanol (TFE) as cosolvent was compared to a total cell lysate protein extract prepared by a current technique. After 2‐DE separation of the two extracts, their protein patterns clearly differed. About 63% of the proteins identified in the TFE‐extract were predicted to possess at least one transmembrane domain. 2‐D blots probed with sera from cancer patients or from healthy volunteers showed that, as expected, additional antigens were provided in the TFE‐extract. Thus, the method described here appeared well suited for proteomic investigation of potential biomarkers undetected by current techniques.
Improving sensitivity of electrophoretic heteroduplex analysis using nucleosides as additives: Application to the breast cancer predisposition gene BRCA2
Authors: Weber Jérémie , Looten Rachelle , Houdayer Claude , Stoppa‐Lyonnet Dominique , Viovy Jean‐Louis
Published: March 2006

A new method for the detection of unknown mutations, enhanced mismatch mutation analysis (EMMA), is proposed. It is based on electrophoretic heteroduplex analysis (HDA). The resolution is considerably improved, thanks to the combination of high‐resolution block‐copolymer sieving matrix, and nucleosides as additives in the electrophoretic medium. The EMMA method is compared to denaturing HPLC (DHPLC) in a large‐scale study of mutations in the breast cancer‐associated gene BRCA2, involving 4655 DNA amplicons from 94 patients. The rate of false positives was 0.09%. The raw success rate, without optimization of the amplicons tiling, was 94%, a value much higher than that achieved earlier with HDA, and comparable with that obtained with DHPLC. An analysis of the missed mutations suggest that the success rate could be improved up to about 97%, simply by redesigning the amplicons, while retaining the speed, cost effectiveness, and simplicity of the method.