bluuebunny/crossref_metadata_2025 huggingface dataset:
Functional morphology of the sonic apparatus in Ophidion barbatum (Teleostei, Ophidiidae)
Authors: Parmentier E. , Fontenelle N. , Fine M.L. , Vandewalle P. , Henrist C.
Published: November 2006

Most soniferous fishes producing sounds with their swimbladder utilize relatively simple mechanisms: contraction and relaxation of a unique pair of sonic muscles cause rapid movements of the swimbladder resulting in sound production. Here we describe the sonic mechanism for Ophidion barbatum, which includes three pairs of sonic muscles, highly transformed vertebral centra and ribs, a neural arch that pivots and a swimbladder whose anterior end is modified into a bony structure, the rocker bone. The ventral and intermediate muscles cause the rocker bone to swivel inward, compressing the swimbladder, and this action is antagonized by the dorsal muscle. Unlike other sonic systems in which the muscle contraction rate determines sound fundamental frequency, we hypothesize that slow contraction of these antagonistic muscles produces a series of cycles of swimbladder vibration. J. Morphol., 2006. © 2006 Wiley‐Liss, Inc.
Simultaneous determination of monomethylmercury, monobutyltin, dibutyltin and tributyltin in environmental samples by multi‐elemental‐species‐specific isotope dilution analysis using electron ionisation GC‐MS
Authors: Moreno Maria Jimenez , Pacheco‐Arjona Jaime , Rodríguez‐González Pablo , Preud'Homme Hugues , Amouroux David , Donard Olivier F. X.
Published: November 2006

In this work, the simultaneous determination of four organometallic species (monomethylmercury, monobutyltin, dibutyltin and tributyltin) in environmental samples by using a GC‐MS system with electron ionisation has been established. The measurement of isotope ratios in each species was accomplished by selecting the most adequate molecular cluster, and simple mathematical equations were applied to correct the contributions of 13C from the organic groups attached to the tin and mercury atoms. The influence of different parameters such as dwell time on the precision and accuracy of the measured isotope ratios in each target species has also been studied. The determination and the sample preparation procedures presented in this work were first individually validated by analysing several certified reference materials for butyltin compounds (mussel tissue CRM‐477 and marine sediment SOPH‐1) and for monomethylmercury (tuna fish CRM‐464) using an innovative focused microwave technology for the extraction of the species from the solid samples. Additionally, the simultaneous determination of the four species was successfully validated by obtaining quantitative recoveries in spiked natural waters and by analysing the certified reference material BCR‐710 (certified in tributyltin and monomethylmercury). The values obtained in such certified tissue were fully in agreement not only with the certified mass fractions but also with the proposed indicative values for mono‐ and dibutyltin. Copyright © 2006 John Wiley & Sons, Ltd.
Mass spectrometry in ionospheric research
Authors: Ferguson Eldon E.
Published: November 2006

Mass sectrometry played a key role in the development of the understanding of the earth's ionosphere. Of primary importance was its use for in situ atmospheric measurements of the ion and neutral composition of the atmosphere. Mass spectrometry has also played an essential role in the laboratory measurement of critical ionospheric molecular processes. Examples of both are given. © 2006 Wiley Periodicals, Inc., Mass Spec Rev 26:142–149, 2007
Mesophase Separation of Diblock Copolymer Confined in a Cylindrical Tube Studied by Dissipative Particle Dynamics
Authors: Feng Jian , Liu Honglai , Hu Ying
Published: November 2006

Summary: The morphologies of diblock copolymers confined in a cylindrical tube have been investigated by the dissipative particle dynamics (DPD) method. Results indicate that the morphology depends on the volume ratio of the immiscible blocks, the diameter of the cylindrical tube and the interactions between the blocks and between the confinement wall and blocks. For symmetric diblock copolymers, when the tube wall is uniform toward the two blocks, perpendicular lamellae or a stacked disk morphology are generally formed except when the diameter of the cylindrical tube is very small; in that case, a special bi‐helix morphology forms because of the entropy effect. When the tube wall is non‐uniform, as the diameter of the tube increases, perpendicular lamellae are first formed, then changing to parallel lamellae and, finally, back to perpendicular lamellae again. An intermediate morphology characterizing the transition between perpendicular and parallel lamellae is observed. If the non‐uniformity of the wall is further enhanced, only parallel lamellae can be found. In the case of asymmetric diblock copolymers, more complex morphologies can be obtained. Multi‐cylindrical micro‐domains and a multilayer helical phase as well as other complex pictures are observed. Generally, the morphologies obtained could find their counterparts from experiments or Monte Carlo simulations; however, differences do exist, especially in some cases of asymmetric diblock copolymers.

Bi‐helix and stacked disks morphologies of A5B5 diblock copolymer confined in two different neutral nanocylinders.

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Bi‐helix and stacked disks morphologies of A5B5 diblock copolymer confined in two different neutral nanocylinders.
Dissipative Particle Dynamics Simulations of Polymer Brushes: Comparison with Molecular Dynamics Simulations
Authors: Pal Sandeep , Seidel Christian
Published: November 2006

Summary: The structure of polymer brushes is investigated by dissipative particle dynamics (DPD) simulations that include explicit solvent particles. With an appropriate choice of the DPD interaction parameters $a_{ij}$, we obtain good agreement with previous molecular dynamics (MD) results where the good solvent behavior has been modeled by an effective Lennard–Jones potential. The present results confirm that DPD simulation techniques can be applied for large length scale simulations of polymer brushes. A relation between the different length scales $r_{\rm c}$ and $\sigma$ is established.

Polymer brush at a solid–liquid interface.

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Polymer brush at a solid–liquid interface.
Interval estimation of mean response time for a G/M/1 queueing system: empirical Laplace function approach
Authors: Chu Yunn‐Kuang , Ke Jau‐Chuan
Published: November 2006

Mean response time is an important performance measure for a queueing system. In this paper, we propose a consistent and asymptotically normal (CAN) estimator of the mean response time for a G/M/1 queueing system, which is based on the fixed point of empirical Laplace function. The confidence interval for the mean response time can be constructed by applying the proposed CAN estimator and its estimated variance. And we carried out a simulation study to perform the accuracy of the constructed confidence interval by calculating the coverage percentage and the relative average length of confidence interval. Detailed discussions of all simulation results for three various models of G/M/1‐type system are presented and some valuable conclusions are provided. Copyright © 2006 John Wiley & Sons, Ltd.
Methylglyoxal in food and living organisms
Authors: Nemet Ina , Varga‐Defterdarović Lidija , Turk Zdenka
Published: November 2006

Methylglyoxal (MG) is a highly reactive α‐oxoaldehyde formed endogenously in numerous enzymatic and nonenzymatic reactions. It modifies arginine and lysine residues in proteins forming advanced glycation end‐products such as Nδ‐(5‐methyl‐4‐imidazolon‐2‐yl)‐L‐ornithine (MG‐H1), 2‐amino‐5‐(2‐amino‐5‐hydro‐5‐methyl‐4‐imidazolon‐1‐yl)pentanoic acid (MG‐H2), 2‐amino‐5‐(2‐amino‐4‐hydro‐4‐methyl‐5‐imidazolon‐1‐yl)pentanoic acid (MG‐H3), argpyrimidine, Nδ‐(4‐carboxy‐4,6‐dimethyl‐5,6‐dihydroxy‐1,4,5,6‐tetrahydropyrimidine‐2‐yl)‐L‐ornithine (THP), Nε‐(1‐carboxyethyl)lysine (CEL), MG‐derived lysine dimer (MOLD), and 2‐ammonio‐6‐({2–[4‐ammonio‐5‐oxido‐5‐oxopently)amino]‐4‐methyl‐4,5‐dihydro‐1H‐imidazol‐5‐ylidene}amino)hexanoate (MODIC), which have been identified in vivo and are associated with complications of diabetes and some neurodegenerative diseases. In foodstuffs and beverages, MG is formed during processing, cooking, and prolonged storage. Fasting and metabolic disorders and/or defects in MG detoxification processes cause accumulation of this reactive dicarbonyl in vivo. In addition, the intake of low doses of MG over a prolonged period of time can cause degenerative changes in different tissues, and can also exert anticancer activity. MG in biological samples can be quantified by HPLC or GC methods with preliminary derivatization into more stable chromophores and/or fluorophores, or derivatives suitable for determination by MS by use of diamino derivatives of benzene and naphthalene, 6‐hydroxy‐2,4,5‐triaminopyrimidine, cysteamine, and o‐(2,3,4,5,6‐pentafluorobenzyl) hydroxylamine. The methods include three basic steps: deproteinization, incubation with derivatization agent, and chromatographic analysis with or without preliminary extraction of the formed products.
Trapping reactions of reactive carbonyl species with tea polyphenols in simulated physiological conditions
Authors: Lo Chih‐Yu , Li Shiming , Tan Di , Pan Min‐Hsiung , Sang Shengmin , Ho Chi‐Tang
Published: November 2006

The carbonyl stress that leads to the formation of advanced glycation end products (AGEs) in diabetes mellitus has drawn much attention recently. Reactive alpha‐dicarbonyl compounds, such as glyoxal (GO) and methylglyoxal (MGO), have been shown to be a high potential glycation agent in vitro and in vivo. In this study, epicatechins in green tea and theaflavins in black tea were found to be able to reduce the concentration of MGO in physiological phosphate buffer conditions. Modified MGO derivatization for GC/flame ionization detector (FID) method in quantification was systematically conducted. In molar ratio of 3 (MGO/polyphenol), theaflavin‐3,3′‐digallate (TF3) in theaflavins and (–)‐epigallocatechin (EGC) in epicatechins showed the highest MGO reduction at 66.65 and 45.74%, respectively, after 1 h of incubation. In kinetic study (molar ratio of MGO/polyphenol = 1:1), rapid MGO reduction occurred within 10 min. Identities of primary adducts between (–)‐epigallocatechin gallate (EGCG) and MGO were determined. Newly generated stereoisomers at the C8 position of EGCG A‐ring were isolated with a chiral column, and structurally confirmed by 2‐D NMR analyses.
Single nucleotide polymorphism analysis of the enterocin P structural gene of Enterococcus faecium strains isolated from nonfermented animal foods
Authors: Arlindo Samuel , Calo Pilar , Franco Carlos , Prado Marta , Cepeda Alberto , Barros‐Velázquez Jorge
Published: November 2006

The bacteriocins produced by two lactic acid bacteria isolated from nonfermented fresh meat and fish, respectively, and exhibiting a remarkable antilisterial activity, were characterized. Bacteriocinogenic strains were identified as Enterococcus faecium and the maximum bacteriocin production by both strains was detected in the stationary phase of growth. The activity against Listeria monocytogenes was maintained in pH range of 3–7 and was stable in both strains after heating at 100 or 121°C. The genes coding for enterocin P were detected, isolated, and sequenced in both E. faecium strains. They exhibited DNA/DNA homology in the 87.1–97.2% range with respect to the other four enterocin P genes reported so far. Three single nucleotide polymorphism events, silent at the amino acid level, were detected at nucleotide positions 45 (G/A), 75 (A/G), and 90 (T/C) in E. faecium LHICA 28–4 and may explain the differences reported for those loci in other enterocin P‐producing E. faecium strains. This work provides the first description of enterocin P‐producing E. faecium strains in nonfermented foodstuffs and, in the case of E. faecium LHICA 51, the first report of an enterocin P‐producing strain isolated from fish so far.
Chemistry and genotoxicity of caramelized sucrose
Authors: Kitts David D. , Wu C. H. , Kopec A. , Nagasawa T.
Published: November 2006

Caramelization of a 1% sucrose solution at 180°C accompanied characteristic changes in pH, Mr, UV‐absorbance, and fluorescence values as well as increased reducing power activity after 40–60 min. Similar changes occurred to sucrose heated at 150°C, after 150–240 min. Bioactivity of caramelized sucrose samples was tested for mutagenic activity, using Salmonella typhimurium strains TA‐98 and TA‐100, respectively, as well as the Saccharomyces D7 yeast strain for mitotic recombination and Chinese hamster ovary cells (CHO) to assess clastogenicity. Caramelized sucrose expressed no mutagenicity in the TA‐98 strain, but gave positive (p < 0.05) results with the TA‐100, base‐pair substitution strain. Similarly, mitotic recombination in the Saccharomyces D7 yeast strain and clastogenic activity in CHO cells were induced when exposed to caramelized sucrose. In the all cases, preincubation with S‐9 reduced (p < 0.05) the mutagenic activities of caramelized sucrose. Fractionation of the caramelized sucrose into volatile and nonvolatile compounds was performed and tested for clastogenicity using CHO cells. Volatile components contributed approximately 10% to total clastogenicity, which was enhanced by the presence of S‐9. Nonvolatile components recovered, consisting of relatively lower Mr, gave highest (p < 0.05) clastogenic activity, denoting that higher Mr caramel colors are relatively free of this property.
Unfolded protein response and aggresome formation in hereditary reducing‐body myopathy
Authors: Liewluck Teerin , Hayashi Yukiko K. , Ohsawa Maki , Kurokawa Rumi , Fujita Masako , Noguchi Satoru , Nonaka Ikuya , Nishino Ichizo
Published: November 2006

Reducing‐body myopathy (RBM) is a rare myopathy characterized by the presence of unique sarcoplasmic inclusions called reducing bodies (RBs). We characterized the aggresomal features of RBs that contained γ–tubulin, ubiquitin, and endoplasmic reticulum (ER) chaperones, together with a set of membrane proteins, in a family with hereditary RBM. Increased messenger ribonucleic acid and protein levels of a molecular chaperone, glucose‐related protein 78, were also observed. These results suggest that the unfolded protein response caused by the accumulation of misfolded proteins in the endoplasmic reticulum plays an important role in the formation of RBs. Muscle Nerve, 2006
The molecular receptive range of an olfactory receptorin vivo(Drosophila melanogasterOr22a)
Authors: Pelz Daniela , Roeske Tina , Syed Zainulabeuddin , Bruyne Marien de , Galizia C. Giovanni
Published: November 2006

Understanding how odors are coded within an olfactory system requires knowledge about its input. This is constituted by the molecular receptive ranges (MRR) of olfactory sensory neurons that converge in the glomeruli of the olfactory bulb (vertebrates) or the antennal lobe (AL, insects). Aiming at a comprehensive characterization of MRRs inDrosophila melanogasterwe measured odor‐evoked calcium responses in olfactory sensory neurons that express the olfactory receptor Or22a. We used an automated stimulus application system to screen [Ca2+] responses to 104 odors both in the antenna (sensory transduction) and in the AL (neuronal transmission). At 10−2(vol/vol) dilution, 39 odors elicited at least a half‐maximal response. For these odorants we established dose‐response relationships over their entire dynamic range. We tested 15 additional chemicals that are structurally related to the most efficient odors.Ethyl hexanoateandmethyl hexanoatewere the best stimuli, eliciting consistent responses at dilutions as low as 10−9. Two substances led to calcium decrease, suggesting that Or22a might be constitutively active, and that these substances might act as inverse agonists, reminiscent of G‐protein coupled receptors. There was no difference between the antennal and the AL MRR. Furthermore we show that Or22a has a broad yet selective MRR, and must be functionally described both as a specialist and a generalist. Both these descriptions are ecologically relevant. Given that adultDrosophilause approximately 43 ORs, a complete description of all MRRs appears now in reach. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006
Analysis by array CGH of genomic changes associated with the progression or relapse of Wilms' tumour
Authors: Natrajan R , Little SE , Sodha N , Reis‐Filho JS , Mackay A , Fenwick K , Ashworth A , Perlman EJ , Dome JS , Grundy PE , Pritchard‐Jones K , Jones C
Published: November 2006

Despite aggressive salvage regimens, approximately half of all children who suffer a Wilms' tumour recurrence will die of their disease. Although there are increasing data on molecular genetic prognostic factors present in the tumour at diagnosis, there is little information regarding the molecular events that occur with Wilms' tumour progression and relapse. In the present study, microarray‐based comparative genomic hybridization (aCGH) analysis has been carried out on 58 Wilms' tumour samples, which included 38 untreated primary and 20 recurrent tumours. A higher degree of copy number changes was observed in the recurrent tumours (33.0% genomic clones) than in the primary tumour (21.2%). Paired analysis highlighted the acquisition of 15q gain with high levels of IGF1R expression in the tumour recurrence in two cases. The most statistically significant abnormality acquired between diagnosis and relapse was loss of 17p. One case that experienced 17p loss was classified as favourable histology at diagnosis, but exhibited diffuse anaplasia at recurrence and had a homozygous TP53 deletion. Another instructive case with a constitutional 11p13 deletion presented with bilateral tumours and suffered two subsequent recurrences in the left kidney. A somatic WT1 mutation was found only in the right kidney tumour, while the constitutional 11p13 deletion was the only abnormality detected in the initial left kidney tumour by aCGH. The two subsequent relapses in the left kidney contained an accumulation of additional genetic alterations, including an independent WT1 mutation. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Dielectric properties of γ‐irradiated POE highly filled with aluminum hydroxide
Authors: Kim Chonung , He Tao , Jiang Pingkai , Wei Ping , Huang Xingyi , Jin Zhijian
Published: November 2006

The influence of γ irradiation on the dielectric and physicochemical properties of polyethylene‐octene elastomer (POE) containing 120 phr aluminum hydroxide (Al(OH)3) as fillers has been investigated. The dielectric properties of the γ‐irradiated POE highly filled with Al(OH)3 have been measured over a wide range of frequencies (70 kHz–3 MHz). It was found that γ irradiation strongly influences the dielectric properties of the POE composite in the dose range 0–250 kGy. POLYM. ENG. SCI. 46:1721–1727, 2006. © 2006 Society of Plastics Engineers
Effect of N‐phenylmaleimide on a novel chemically bonded polymerizable photoinitiator comprising the structure of planar N‐phenylmaleimide and benzophenone for photopolymerization
Authors: Wang Hongyu , Wei Jun , Jiang Xuesong , Yin Jie
Published: November 2006

A novel chemically bonded polymerizable photoinitiator 4‐[(4‐maleimido)phenoxy]benzophenone (MPBP) comprising the structure of planar N‐phenylmaleimide (NPMI) and benzophenone (BP), compared with the physical mixtures of NPMI/BP or NPMI/4‐hydroxybenzophenone, was investigated to disclose the mutual influence between NPMI and BP. A BP derivative, 4‐phenoxylbenzophenone, was selected as the model compound. Electron spin resonance spectra of such photoredox systems indicated MPBP and BP possess the same initiation mechanism. The large red‐shifted π–π* absorption of MPBP should be because of the phenoxyl group in MPBP but not the maleimide group. The photopolymerization of methyl methacrylate (MMA) and 1,6‐hexanediol diacrylate (HDDA) initiated by those systems, using the unsaturated tertiary amine N,N‐dimethylaminoethyl methacrylate (DMAEMA) as the coinitiator (H donor), was studied through dilatometry and photo‐differential scanning calorimetry. The results showed that MPBP was more efficient for the photopolymerization of MMA and HDDA than its physical mixture counterpart. The high efficiency of MPBP may be mainly because of the interaction between NPMI and BP group but not the phenoxyl group alone. A certain amount of NPMI can accelerate the photopolymerization when added to the formulations, but too much NPMI will eventually decrease the photoefficiency. Copyright © 2006 Society of Chemical Industry
Entirely aqueous synthesis of polyimide–silsesquioxane nanocomposites
Authors: Arkhireeva Anna , Groth Andrew M , Hay John N
Published: November 2006

A novel combination of a modified Stöber sol–gel technique to prepare silsesquioxane nanoparticles with an aqueous synthesis of polyimide resin has been used to prepare polyimide–silsesquioxane nanocomposites. The products have been analysed to ascertain the degree and mode of association between the polyimide matrix and silsesquioxane nanoreinforcement. Thermal analysis techniques have been used to quantify the attraction between the resin and four different surface‐functionalised silsesquioxanes. Scanning electron microscopy has been used to assess qualitatively the nature of the interaction between the two components. In general, aminopropyl–functionalised silsesquioxanes have the lowest level of interaction with the polyimides used in this study, while methyl‐ and phenyl‐functionalised nanoparticles bind more strongly with the resin. Silica nanoparticles have a relatively strong association with the polyimide and appear to be largely attached to the surface of the polymer. Copyright © 2006 Society of Chemical Industry
Crystallinity, thermal properties, morphology and conductivity of quaternary plasticized PEO‐based polymer electrolytes
Authors: Wang Yan‐Jie , Pan Yi , Kim Dukjoon
Published: November 2006

Quaternary plasticized solid polymer electrolyte (SPE) films composed of poly(ethylene oxide), LiClO4, Li1.3Al0.3Ti1.7(PO4)3, and either ethylene carbonate or propylene carbonate as plasticizer (over a range of 10–40 wt%) were prepared by a solution‐cast technique. X‐ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS) indicated that components such as LiClO4 and Li1.3Al0.3Ti1.7(PO4)3 and the plasticizers exerted important effects on the plasticized quaternary SPE systems. XRD analysis revealed the influence from each component on the crystalline phase. DSC results demonstrated the greater flexibility of the polymer chains, which favored ionic conduction. SEM examination revealed the smooth and homogeneous surface morphology of the plasticized polymer electrolyte films. EIS suggested that the temperature dependence of the films' ionic conductivity obeyed the Vogel–Tamman–Fulcher (VTF) relation, and that the segmental movement of the polymer chains was closely related to ionic conduction with increasing temperature. The pre‐exponential factor and pseudo activation energy both increased with increasing plasticizer content and were maximized at 40 wt% plasticizer content. The charge transport in all polymer electrolyte films was predominantly reliant on lithium ions. All transference numbers were less than 0.5. Copyright © 2006 Society of Chemical Industry
Synthesis and characterization of amine‐functionalized amphiphilic block copolymers based on poly(ethylene glycol) and poly(caprolactone)
Authors: KC Remant Bahadur , Bhattarai Shanta Raj , Aryal Santosh , Bhattarai Narayan , Lee Byoung Min , Kim Hak Yong
Published: November 2006

A series of amine‐functionalized block copolymers, poly(caprolactone)‐block‐poly(ethylene glycol) (PCL‐b‐PEG), were synthesized by ring‐opening bulk polymerization (ROP) of ε‐caprolactone (ε‐CL) initiated through the hydroxyl end of the amino poly(ethylene glycol) (PEG) used as a macroinitiator in the presence of stannous 2‐ethylhexonoate [Sn(Oct)2]. The polymerization and end functionality of the polymer were studied by different physicochemical techniques (1H NMR, Fourier transform infrared and X‐ray photoelectron spectroscopy, gel permeation chromatography and thermogravimetric analysis). Thermal, crystalline and mechanical properties of the polymer were thoroughly analyzed using differential scanning calorimetry, wide‐angle X‐ray diffractometry and tensile testing, respectively. The results showed a linear improvement in crystallinity and mechanical properties of the polymer with the content of PEG. Thus the synthesized functional polymers can be used as excellent biomaterials for the delivery of polyanions, as well as macroinitiators for the synthesis of A–B–C‐type block copolymers. Copyright © 2006 Society of Chemical Industry
Zero‐field splitting parameters of quintet 2,6‐dinitrenopyridines
Authors: Chapyshev Sergei V. , Lahti Paul M.
Published: November 2006

The zero field splitting parameters of two 2,6‐dinitrenopyridines were estimated to be |D/hc| ≅ 0.19–0.20 cm−1 and |E/hc| ≅ 0.064–0.066 cm−1 by lineshape simulation of frozen solution X‐band ESR spectra. This large ratio of |E/D| is consistent with a dominating dipolar interaction between the two nitrene units having a relative interaction vector angle of about 114°–116°. UB3LYP/6‐31G* computations of 2,6‐dinitrenopyridine predict a very similar interaction vector angle. These results are quite different from analogous results observed for meta‐dinitrenobenzenes. The experimental zero‐field splitting (zfs) and computational results indicate that the ESR spectroscopy of 2,6‐dinitrenopyridines are dominated by the one‐center interactions between unpaired electrons on the nitrene units (the triplet mononitrene zfs), and the relative geometry of interaction between the mononitrenes caused by the molecular geometry of the dinitrenopyridine (the interaction vector angle). Copyright © 2006 John Wiley & Sons, Ltd.
Cationic copolymerization of ε‐caprolactone and L,L‐lactide by an activated monomer mechanism
Authors: Baśko Małgorzata , Kubisa Przemysław
Published: November 2006

The cationic homopolymerization and copolymerization of L,L‐lactide and ε‐caprolactone in the presence of alcohol have been studied. The rate of homopolymerization of ε‐caprolactone is slightly higher than that of L,L‐lactide. In the copolymerization, the reverse order of reactivities has been observed, and L,L‐lactide is preferentially incorporated into the copolymer. Both the homopolymerization and copolymerization proceed by an activated monomer mechanism, and the molecular weights and dispersities are controlled {number‐average degree of polymerization = ([M]0 − [M]t)/[I]0, where [M]0 is the initial monomer concentration, [M]t is the monomer concentration at time t, and [I]0 is the initial initiator concentration; weight‐average molecular weight/number‐average molecular weight ∼1.1–1.3}. An analysis of 13C NMR spectra of the copolymers indicates that transesterification is slow in comparison with propagation, and the microstructure of the copolymers is governed by the relative reactivity of the comonomers. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 7071–7081, 2006
Synthesis and stability study of dental monomers containing methacrylamidoethyl phosphonic acids
Authors: Xu Xiaoming , Wang Rubin , Ling Long , Burgess John O.
Published: November 2006

Three new dental monomers containing methacrylamidoethyl phosphonic acids were synthesized. The structures of the synthesized monomers were determined with electrospray mass spectrometry (ESMS), Fourier transform infrared, and NMR. The hydrolytic stabilities of the synthesized monomers and a commercial monomer, 2‐methacryloyloxyethyl phosphoric acid (MEP; used as a control), were studied with flow injection (FI)/ESMS, 1H NMR, and 31P NMR analysis of a CD3OD/D2O (4:1 v/v) solution of each monomer before and after storage at 60 °C for 2 months. The 1H NMR and 31P NMR chemical shifts of the monomers 2‐methacrylamidoethylphosphonic acid (I) and N,N′‐[4,4′‐(propane‐2,2‐diyl)‐bis(phenoxy‐2‐hydroxypropyl)]‐bis(2‐methacrylamidoethylphosphonic acid) (II) showed little change after storage at 60 °C for 2 months, but those of MEP changed significantly. FI/ESMS also showed that MEP was nearly completely decomposed, whereas monomers I and II remained largely intact. MEP could react with H2ZrF6 to form ternary zirconium fluoride complexes that were partially soluble in methanol, but all the monomers containing phosphonic acids formed precipitates. This study demonstrates that ESMS is a more sensitive and effective method than NMR for studying the hydrolytic stability or degradation of dental monomers. The new monomers containing methacrylamidoethyl phosphonic acids have higher hydrolytic stability than methacrylate phosphate monomers and may be used in dental bonding agents and other dental materials. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 99–110, 2007
Thermal and mechanical cracking in bis(triisopropylsilylethnyl) pentacene thin films
Authors: Chen Jihua , Tee Chee Keong , Yang Junyan , Shaw Charles , Shtein Max , Anthony John , Martin David C.
Published: November 2006

Bis(triisopropylsilylethnyl) pentacene (TIPS pentacene) was synthesized to increase its solubility in common liquid solvents and, at the same time, enhance the π–π stacking between neighboring acenes in the crystallized state in comparison with unmodified pentacene. Hot‐stage microscopy experiments revealed that during heating voids develop along the long axis of the TIPS pentacene films {along the [210] direction/parallel to the (120) planes} and crystals overlap along the short axis {along the [120] direction/parallel to the (210) planes}. From molecular mechanics simulations, the predominant twin boundaries of (120) and commonly observed cracking planes of (120), (120), and (210) had relatively low surface energies in comparison with planes with similar Miller indices. Organic thin‐film transistors with TIPS pentacene as the active layer were fabricated, and the mobility values decreased from 0.4–1.0 cm2/V s before cracking to ∼0.2 cm2/V s after cracking. To maintain the high charge carrier mobility of TIPS pentacene devices, these cracks should be avoided. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3631–3641, 2006
Mixed solvent effect on lithium‐coordination to poly(ethylene oxide)
Authors: Hakem Ilhem F. , Lal Jyotsana , Bockstaller Michael R.
Published: November 2006

This article presents a comparative study of the structure formation of poly (ethylene oxide) PEO/Li complexes in aqueous and acetonitrile solutions using small‐angle neutron scattering (SANS). We demonstrate that in acetonitrile solutions, Li‐cations coordinate to the ether–oxygen of the monomeric unit, and this results in charging and stretching of the polymer chains. This is found to be in contrast to aqueous solutions, where the ions remain free in solution. In particular, we demonstrate that the “binding” and “screening” regimes that were observed in case of PEO/K+ solutions in acetonitrile are also found in the respective PEO/Li+ solutions. The addition of water to solutions in acetonitrile increasingly diminishes the ion‐coordination to the polymer, eventually resulting in neutral polymer chains at water contents above ϕ*water = 30% (w/v). The preferential adsorption of water on PEO in mixtures of acetonitrile and water is evidenced by the pronounced stretching of polymer chains, in particular, at a water content of ϕwater = 25% and 33.33% (w/v) where complete stretching of the chains is observed. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3642–3650, 2006
Relationships between unfolded configurations of proteins and dynamics of folding to the native state
Authors: Gursoy Attila , Keskin Ozlem , Turkay Metin , Erman Burak
Published: November 2006

We compare folding trajectories of chymotrypsin inhibitor (CI2) using a dynamic Monte Carlo scheme with Go‐type potentials. The model considers the four backbone atoms of each residue and a sphere centered around Cβ the diameter of which is chosen according to the type of the side group. Bond lengths and bond angles are kept fixed. Folding trajectories are obtained by giving random increments to the φ and ψ torsion angles with some bias toward the native state. Excluded volume effects are considered. Two sets of 20 trajectories are obtained, with different initial configurations. The first set is generated from random initial configurations. The initial configurations of the second set are generated according to knowledge‐based neighbor dependent torsion probabilities derived from triplets in the Protein Data Bank. Compared to chains with randomly generated initial configurations, those generated with neighbor‐dependent probabilities (i) fold faster, (ii) have better defined secondary structure elements, and (iii) have less number of non‐native contacts during folding. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3667–3678, 2006
Monte Carlo study of the coil‐to‐globule transition of a model polymeric system
Authors: Rissanou Anastassia N. , Anastasiadis Spiros H. , Bitsanis Ioannis A.
Published: November 2006

Monte Carlo computer simulations of single, flexible, self‐avoiding chains on a cubic lattice have been performed upon conditions of increasing segment–segment cohesive energy (deteriorating solvent quality). The simulations spanned a wide range of chain lengths (20–10,000, i.e., up to molecular weights of a few millions) and cohesive energies (0.0–0.45kBT, i.e., from athermal to very poor solvents). The chain length dependence of the chain size in poor solvents was characterized by a wide plateau of almost null growth for intermediate chain lengths. This plateau was linked to the development of the incipient constant density core, while genuine power law dependence (1/3) was not reached even for the longest chains and poorest solvents simulated here. The mere appearance of a core required substantial chain lengths (higher than 1000; molecular weights of a few hundred thousands), while short chains underwent a gradual densification devoid of any qualitative changes in the density distribution. Sufficiently long chains became more but not quite spherical and underwent a reasonably sharp second order phase transition. The findings were generally in agreement with predictions of mean‐field theory and with the use of the standard scaling variables, despite slight inconsistencies. Nevertheless, the results stress the fact that short chains never form a constant density core and that core‐dominance on the globule's properties (“volume approximation”) is only valid for extraordinarily long chains [molecular weight of O(109)], an effect linked to the relatively diffuse nature of the surface layer and originating from chain connectivity in conjunction with spherical geometry. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3651–3666, 2006
The Effects of Reaction Conditions on Liquid‐Phase Hydroxyl Radical Production in Gas‐Liquid Pulsed‐Electrical‐Discharge Reactors
Authors: Sahni Mayank , Locke Bruce R.
Published: November 2006

Summary: High‐voltage gas‐, liquid‐ and gas‐liquid‐phase pulsed electrical discharges are an emerging technique in environmental pollutant degradation, which that are characterized by the production of hydroxyl radicals as the primary degradation species. The initiation and propagation of the electrical discharges depends on several physical, chemical, and electrical parameters. These parameters also influence the physical and chemical characteristics of the discharges, including the production of reactive species such as OH•, H• and H2O2. This paper focuses on quantification of hydroxyl radicals using chemical probes (DMSO and NaTA) in three different reactor configurations: reference (purely liquid‐phase discharge), hybrid‐series (combined gas‐liquid discharge), and hybrid‐parallel (combined gas‐liquid discharge) for a wide range of operating conditions. The operating conditions that are evaluated are: input power, initial conductivity of solution, temperature of solution, presence of radical scavengers and additives in solution.

Schematic view of the different hybrid reactor configurations (series and parallel) used in this study.

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Schematic view of the different hybrid reactor configurations (series and parallel) used in this study.
Wear Resistance of Low‐Temperature Plasma‐Polymerized Organosilica Deposited on Poly(ethylene terephthalate): The Effect of O2 Addition
Authors: Lin Yung‐Sen , Chen Ching‐Lun
Published: November 2006

Summary: The wear resistance of PET substrates can be enhanced by low‐temperature plasma‐polymerization of organosilica (SiOxCy); the effect of varying oxygen flow rates is investigated in this paper. It was found that the low‐temperature plasma‐polymerization of SiOxCy with tetramethylsilane (TMS) and oxygen (O2) at room temperature (23 °C) can be used for improving the wear resistance of PET substrates, as demonstrated by scratch tests. The wear resistance of PET substrates was greatly enhanced from the completely scratched of the untreated PET substrates to no scratched of TMS/O2 plasma‐polymerized PET substrates, which were obtained at high oxygen flow rates with a steel wool for 300 cycles at 300 g loading. The results of this study indicate that the wear resistance of the treated PET substrates was highly dependent on the surface characteristics of bare PET substrates. The hardness of PET substrates was determined by the pencil test, while the surface morphology was monitored by AFM. The atomic compositions and chemical bonding of the TMS/O2 plasma‐polymerized organosilicas were analyzed by XPS.

The wear loss ΔT(%) for the TMS/O2 plasma‐polymerized PET substrates for various oxygen flow rates.

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The wear loss ΔT(%) for the TMS/O2 plasma‐polymerized PET substrates for various oxygen flow rates.
Fine‐Particle Collection Using an Electrostatic Precipitator Equipped With an Electrostatic Flocking Filter as the Collecting Electrode
Authors: Sung Bong‐Jo , Aly Ahmed , Lee Sung‐Hwa , Takashima Kazunori , Kastura Shinji , Mizuno Akira
Published: November 2006

Summary: In recent years, special environmental concern is directed towards controlling the emission of fine particles (from 0.1 to 1.0 µm). These fine particles possibly cause serious health hazards because of heavy metals and toxic compounds adsorbed on the particles. To improve the collection efficiency of fine particles, the electrostatic flocking technique has been employed in this study. This technique is based on increasing the surface area of the collecting electrode and on producing a gradient force at the tip of fibers to suppress the re‐entrainment. In this article, an experimental study was performed to evaluate the effect of fine fibers on the collection efficiency of fine particles using the ESP with electrostatic flocking electrodes as collecting plates. The ESP achieved a collection efficiency of about 95% at a d.c. voltage of 9 kV, which was higher than that of flat‐plate electrode for fine particles (0.3–0.5 µmin diameter) with a short residence time (0.06 s). We confirmed that the fine particles agglomerated at the tip of the flocking fibers. These results indicate that the new type of ESP examined in this study is effective to improve the removal performance of fine particles.

Model of the precipitation and the re‐entrainment suppression in an ESP equipped with an EF electrode.

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Model of the precipitation and the re‐entrainment suppression in an ESP equipped with an EF electrode.
Kinetic Modeling of the NF3 Decomposition via Dielectric Barrier Discharges in N2/NF3 Mixtures
Authors: Chen Hsin Liang , Lee How Ming , Chang Moo Been
Published: November 2006

Summary: Emission of PFCs (perfluorocompound) has attracted much attention in recent years due to its relatively high contribution to the global warming. Non‐thermal plasma is one of the most promising technologies to effectively control the PFC emissions. In this study, a cylindrical DBD (dielectric barrier discharge) reactor is adopted for the treatment of NF3‐containing streams. Besides the experimental work, a numerical model is also developed for better understanding of the reaction mechanism of NF3 abatement in N2/NF3 mixtures. Good agreement is observed between the experimental data and the simulation results. Simulation results indicate that the electrons and the N atoms are the major active species responsible for the NF3 decomposition. In addition, N2(A3Σ) metastables plays a significant role in the NF3 abatement. A simplified mechanism for the NF3 decomposition in the N2 – NF3 plasmas is proposed as well.

Reaction mechanisms for the decomposition of NF3 in a N2 – NF3 plasma.

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Reaction mechanisms for the decomposition of NF3 in a N2 – NF3 plasma.
Control of DC Corona Discharge Modes by a Switching Operation
Authors: Kanazawa Seiji , Ikeda Takafumi , Mitsugi Fumiaki , Ohkubo Toshikazu , Nomoto Yukiharu
Published: November 2006

Summary: Glow and streamer discharges are well known as the typical modes for positive DC corona discharges. In this study, a new method for the control of the corona discharges modes is proposed. The grounded electrode is divided and a switch is attached to one of the electrodes. The results showed that corona discharge mode could be controlled by this switching operation. As the applied positive voltage is increased, corona glow is mostly generated in air at atmospheric pressure, but this mode is changed to streamer mode by switching‐off the operation. Moreover, glow and streamer corona discharges from one stressed wire electrode can be generated simultaneously by modifying the design of the divided plane electrodes and by the switching operation. A mechanism of the controlled streamer discharge by the switching operation is discussed.

Simultaneous generation of glow and streamer corona discharges from one stressed wire electrode.

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Simultaneous generation of glow and streamer corona discharges from one stressed wire electrode.
Polymerization in Nanocrystalline Diamond Films by Oxygen Incorporation
Authors: Teii Kungen , Ikeda Tomohiro
Published: November 2006

Summary: Structure and resistivity of nanocrystalline diamond films deposited using microwave Ar‐rich/O2/CH4 plasmas have been examined as a function of the O2/CH4 ratio from 0 to 0.53. Addition of O2 to Ar‐rich/CH4 plasmas likely reduced the density of C2 radicals due to loss reactions of O atoms with CH4 and CHx radicals. The Raman peak of diamond at 1 332 cm−1 was overlapped by the D peak of sp2‐bonded, disordered carbon and its intensity was a little enhanced by the O2 addition, while the average size of sp2‐bonded carbon clusters in nondiamond phases was increased. Oxygen was incorporated into the films in forms of CO bonds, which bridged the carbon clusters themselves, and formed polymer‐like, large‐unit structures. The resistivity of the films was drastically increased from the order of 10−4 up to 104 Ω · m with a small O2 addition (1.2 vol.‐% in total pressure), providing novel sensor and storage applications based on oxygen incorporation and desorption.

Decomposition of a Raman spectrum showing the diamond, D and G modes of amorphous carbon, and trans‐polyacetylene peaks. The insert represents a typical SEM image showing a film surface.

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Decomposition of a Raman spectrum showing the diamond, D and G modes of amorphous carbon, and trans‐polyacetylene peaks. The insert represents a typical SEM image showing a film surface.
Particulate Matter Removal from Diesel Exhaust Gases by a Combination of Corona Discharge and Water or Oil Bath
Authors: Yoshioka Yoshio , Tashiro Yasuhiro , Ueda Takashi , Ota Yukihiro , Nakano Koichi
Published: November 2006

Summary: As an efficient PM removal method from diesel exhausts, we developed a new method using a combination of a DC corona discharge and oil or water trays. The PM removal device generates DC corona discharges on oil or water filled in trays, thereby creating charges on the PMs, which can then be accelerated by an electric field towards the oil or water bath. The amount of PM absorbed in oil is determined by measuring light transmission. The discharge current on water is higher than that on oil. The difference of these discharge currents is considered to be due to the difference in ion mobility of the two liquids. An equation for PM removal characteristics is proposed. Using the equation, the PM removal by our device is estimated to be more than 85%.

Experimental system for PM removal from diesel engine exhaust gas.

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Experimental system for PM removal from diesel engine exhaust gas.
Transient Barrier Discharge Characteristics of Parallel‐Plate‐Type, Packed‐Bed, Non‐Thermal Plasma Reactor Under High‐Humidity Conditions
Authors: Chang Jen‐Shih , Uchida Yoshihisa , Urashima Kuniko , Taylor Roy
Published: November 2006

Summary: Barrier discharge has been used for ozone generation for water treatments and pollutant gas removal. An experiment has been conducted to observe transient barrier discharge characteristics of parallel‐plate‐type, 3 mm diameter, spherical glass beads packed‐bed, non‐thermal plasma reactors under high‐humidity conditions. The results show that: 1) steady operation of the reactor requires 5 to 10 min of operation under an initial 20 to 80% relative humidity at 20 °C in air, as a result of the desorption of water from the packed materials, 2) the usual method to determine discharge power using a Q‐V Lissajous figure may be distorted by adsorption/desorption of water vapor from the surface, and 3) since the surface of the packed material is heated to 50 to 160 °C, the mechanism of desorption may be a result of pure thermal effects.

Change in reactor surface temperature with time.

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Change in reactor surface temperature with time.
Contribution of Plasma Control Technology for Aerodynamic Applications
Authors: Moreau Eric , Louste Christophe , Artana Guillermo , Forte Maxime , Touchard Gérard
Published: November 2006

Summary: During these past ten years, plasma actuators have been envisaged to control air flows. Usually, two main kinds of plasma actuators are available: the DC discharge actuator and the dielectric barrier discharge (DBD) actuator, but also some combinations of both systems are now being studied. In this paper we present the results obtained with these different kinds of actuators. The control parameters, the electrical behaviors, and the mechanical efficiencies of the actuators are given. Aerodynamic experiments have been made in several wind tunnels using Particle Image Velocimetry (P.I.V.), visualization, Laser Dopler Velocimetry and special “Pitot” tube techniques. Advantages and disadvantages of each actuator are discussed, and finally some aerodynamic applications are shown.

Effect of a discharge on the airflow around a NACA body.

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Effect of a discharge on the airflow around a NACA body.