bluuebunny/crossref_metadata_2025 huggingface dataset:
Screening of siRNA target sequences by using fragmentized DNA
Authors: Kasim Vivi , Taira Kazunari , Miyagishi Makoto
Published: March 2006

Background

RNA interference (RNAi) has become a powerful tool in silencing target genes in various organisms. In mammals, RNAi can be induced by using short interfering RNA (siRNA). The efficacy of inducing RNAi in mammalian cells by using siRNA depends very much on the selection of the target sequences.

Methods

We developed an siRNA target sequence selection system by first constructing parallel‐type siRNA expression vector libraries carrying siRNA expression fragments originating from fragmentized target genes, and then using a group selection system. For a model system, we constructed parallel‐type siRNA expression vector libraries against DsRed and GFP reporter genes.

Results

We carried out the first screening of groups containing more than 100 random siRNA expression plasmids in total for each target gene, and successfully obtained target sequences with very strong efficacy. Furthermore, we also obtained some clones that express dsRNAs of various lengths that might induce cytotoxicity.

Conclusions

This system should allow us to perform screening for powerful target sequences, by including all possible target sequences for any gene, even without knowing the whole sequence of the target gene in advance. At the same time, target sequences that should be avoided due to cytotoxicity can be identified. Copyright © 2006 John Wiley & Sons, Ltd.
Eddy‐current induction in extended metallic parts as a source of considerable torsional moment
Authors: Graf Hansjörg , Lauer Ulrike A. , Schick Fritz
Published: March 2006

Purpose

To examine eddy‐current‐provoked torque on conductive parts due to current induction from movement through the fringe field of the MR scanner and from gradient switching.

Materials and Methods

For both cases, torque was calculated for frames of copper, aluminum, and titanium, inclined to 45° to B0 (maximum torque case). Conditions were analyzed in which torque from gravity (legal limit, ASTM F2213‐02) was exceeded. Experiments were carried out on a 1.5 T and a 3 T scanner for copper and titanium frames and plates (≈50 × 50 mm2). Movement‐induced torque was measured at patient table velocity (20 cm/second). Alternating torque from gradient switching was investigated by holding the specimens in different locations in the scanner while executing sequences that exploited the gradient capabilities (40 mT/m).

Results

The calculations predicted that movement‐induced torque could exceed torque from gravity (depending on the part size, electric resistance, and velocity). Two experiments on moving conductive frames in the fringe fields of the scanners confirmed the calculations. For maximum torque case parameters, gradient‐switching‐induced torque was calculated to be nearly 100 times greater than the movement‐induced torque. Well‐conducting metal parts located off center vibrated significantly due to impulse‐like fast alternating torque characteristics.

Conclusion

Torque on metal parts from movement in the fringe field is weak under standard conditions, but for larger parts the acceptable limit can be reached with a high static field and increased velocity. Vibrations due to gradient switching were confirmed and may explain the sensations occasionally reported by patients with implants. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Safety and efficacy of a novel hepatobiliary MR contrast agent, Gd‐DTPA‐DeA: Results of phase I and phase II clinical trials
Authors: Tanimoto Akihiro , Kadoya Masumi , Kawamura Yasutaka , Kuwatsuru Ryohei , Gokan Takehiko , Hirohashi Shinji
Published: March 2006

Purpose

To assess the safety, effective dose, and efficacy of a novel hepatobiliary MR contrast agent Gd‐DTPA‐DeA for imaging liver tumors, from the clinical phase I and phase II trials in Japan.

Materials and Methods

In a phase I trial, 33 healthy volunteers were intravenously administered a single dose of 0.03–10 μmol/kg of Gd‐DTPA‐DeA. In a nationwide phase II trial, 80 patients suspected to have hepatic mass were divided into three dosing groups: 2.5, 5.0, or 7.5 μmol/kg. T1‐weighted gradient echo images were obtained before and after Gd‐DTPA‐DeA administration at three time points. Liver signal‐to‐noise ratio (SNR) and lesion‐liver contrast‐to‐noise ratio (CNR) were calculated at each time point. A reading committee evaluated the contrast, diagnostic, and overall efficacy using a five‐point scale.

Results

In a phase I trial, dosages up to 10 μmol/kg were well tolerated by healthy volunteers. In a phase II trial, the contrast, diagnostic, and overall efficacy increased dose‐dependently. The overall efficacy was 63.0%, 85.2%, and 88.0%, for 2.5, 5, and 7.5 μmol/kg, respectively. Liver SNR and CNR increase was greater at late phase than at early phase. No serious adverse events occurred.

Conclusion

Gd‐DTPA‐DeA is a well‐tolerated and promising contrast agent for liver MR imaging. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Raman and infrared spectra of carbonates of calcite structure
Authors: Gunasekaran S. , Anbalagan G. , Pandi S.
Published: March 2006

The Raman and mid‐range infrared spectra have been measured on natural limestone and dolomite minerals. The carbonate minerals show four prominent absorption bands in the regions 1450–1420, 890–870, 720–700 and 1000–1100 cm−1. The positions of the wavenumbers are unique for each carbonate mineral and are thus diagnostic of their mineralogy. Calcite and dolomite groups are characterized by the Raman wavenumbers at 288 and 309 cm−1 and the infrared absorption bands at 712 and 728 cm−1, respectively. The principal wavenumber at 1092 cm−1 in the limestone spectra is accompanied by two satellites with values of 1062 and 1075 cm−1. The observed non‐split peaks ν2 and ν4 in the infrared spectra of limestone indicate the presence of calcite structure in all these samples. The principal reflections occurring at the d‐spacings, 3.03482, 1.91658 and 1.87962 Å, confirm the presence of calcite structure in limestone minerals. The principal reflections occurring at the d‐spacings, 3.037, 1.79179 and 2.19750 Å, confirm the existence of dolomite structure in the dolomite minerals. The calculated lattice parameters for the limestone minerals are: a = 4.9781 Å, c = 17.1188 Å and V = 367.392(Å)3 and the corresponding values for the dolomite minerals are: a = 4.8247 Å, c = 15.9868 Å and V = 322.28 (Å)3. Copyright © 2006 John Wiley & Sons, Ltd.
Surface‐enhanced resonance Raman spectroscopy of rifamycins on silver nanoparticles: insight into their adsorption mechanisms
Authors: Howes Barry D. , Scatragli Silvia , Marzocchi Mario P. , Smulevich Giulietta
Published: March 2006

Three widely used antibiotics from the rifamycin family, rifamycin SV sodium salt, rifampicin and rifaximin, have been characterized by resonance Raman (RR) and surface‐enhanced resonance Raman spectroscopy (SERRS). SERRS spectra were recorded using aqueous silver colloidal dispersions prepared with two reducing agents, sodium borohydride and hydroxylamine hydrochloride, for a range of pH values to identify the SERRS‐active substrate surface most suitable for each of the three antibiotics. Rifampicin was found to give intense SERRS signals only for the borohydride‐reduced colloid and only at pH < 7.7, whereas the hydroxylamine HCl‐reduced colloid was the best substrate for rifaximin, giving considerably more intense SERRS spectra than the borohydride colloid. SERRS spectra of rifaximin were observed only at pH < 7.0. It is proposed that the marked pH dependence of the SERRS enhancement results from a transition from an anionic to a neutral zwitterionic state. SERRS spectra of rifamycin SV were not observed for any experimental conditions. The antibiotics display remarkably contrasting SERRS behaviour, reflecting differences in the nature of the substituent groups on the chromophore ring. A vibrational assignment of the RR spectra and detailed comparison between the RR and SERRS data have given insight into the mechanism of adsorption of the antibiotics onto the Ag surface. Rifampicin and rifaximin adsorb adopting an approximately similar vertical orientation of the chromophore ring with respect to the surface; however, rifampicin adsorbs by direct chemical interaction with the Ag whereas rifaximin does not form a direct bond with the Ag surface. Copyright © 2006 John Wiley & Sons, Ltd.
The micro Raman analysis of paint evidence in criminalistics: case studies
Authors: Buzzini Patrick , Massonnet Geneviève , Monard Sermier Florence
Published: March 2006

Paint is a widely used material, and painted objects are often encountered in criminal cases. The present article illustrates forensic cases involving paint evidence. The integration of Raman spectroscopy in the analytical sequence provides useful information about the main pigment(s) present in paint samples. One of the main advantages of micro Raman spectroscopy is the possibility of carrying outin situmeasurements of paint smears directly on their support, thereby avoiding the handling and contamination of small trace particles. Raman spectroscopy also adds discriminating power to the standard sequence of paint analysis, which is an important added value in forensic science. Six cases submitted to our laboratory are described in order to show the versatility of application of this technique. Cases including automotive, household and spray paints were submitted to such analyses. Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR) provide important and complementary information to characterise unknown samples. Copyright © 2006 John Wiley & Sons, Ltd.
Raman spectroscopic study of the heterogeneity of microcolonies of a pigmented bacterium
Authors: Goodwin James R. , Hafner Louise M. , Fredericks Peter M.
Published: March 2006

Small colonies (90–350 µm in diameter) of the pigmented halophilic bacterium Halobacterium salinarium have been studied by Raman microspectroscopy using excitation at 632.8 nm. The Raman spectra were dominated by bands due to carotenoid compounds. The intensity of the pigment bands varied across the diameter of the colonies in a way that suggested the presence of concentric rings of higher pigment concentration. Although the colonies were grown in a transparent incubator in an open laboratory, it was demonstrated that the rings were not a result of the diurnal variation of light and dark. These results support a proposed model relating cell motility and cell concentration. Copyright © 2006 John Wiley & Sons, Ltd.
Conformational temperature dependence of a poly(ethylene‐co‐acrylic acid) stationary phase investigated by nuclear magnetic resonance spectroscopy and liquid chromatography
Authors: Meyer Christoph , Pascui Ovidiu , Reichert Detlef , Sander Lane C. , Wise Stephen A. , Albert Klaus
Published: March 2006

A polymer‐based RP sorbent was prepared by immobilizing a poly(ethylene‐co‐acrylic acid) copolymer with an acid mass fraction of 5% on silica by using a 3‐glycidoxypropyl linkage. 13C cross‐polarization/magic angle spinning NMR spectroscopy of the sorbent, either in the dry state or suspended in the mobile phase, showed an increase in mobility at elevated temperatures. Alkyl chain segments with gauche conformations were more mobile than chain segments with trans conformations. The strength of the 13C‐1H dipolar couplings in the alkyl chains was measured using the constant time dipolar and chemical shift pulse sequence, revealing less molecular motion for the trans conformation. Non‐linear van't Hoff plots were observed for separations of shape‐constrained solutes (such as geometric β‐carotene isomers and polycyclic aromatic hydrocarbons). At higher temperatures, the retention behavior was similar to that of monomeric C18 sorbents, whereas at ambient and lower temperatures, enhanced shape‐selective properties were exhibited similar to those of polymeric C30 sorbents.
Preparation and application of HPLC chiral stationary phases based on (+)‐(18‐crown‐6)‐2,3,11,12‐tetracarboxylic acid
Authors: Hyun Myung Ho
Published: March 2006

Preparation of liquid chromatographic chiral stationary phases (CSPs) based on (+)‐(18‐crown‐6)‐2,3,11,12‐tetracarboxylic acid and their application are reviewed. The various methods of connecting (+)‐(18‐crown‐6)‐2,3,11,12‐tetracarboxylic acid to silica gel covalently or dynamically are demonstrated. The CSPs based on (+)‐(18‐crown‐6)‐2,3,11,12‐tetracarboxylic acid have been very successful for the resolution of various primary amino compounds with the use of an aqueous mobile phase containing organic and acidic modifiers. In addition, the resolution of secondary amino compounds including β‐blockers and N‐(3,5‐dinitrobenzoyl)‐α‐amino acids has been demonstrated on a CSP based on (+)‐(18‐crown‐6)‐2,3,11,12‐tetracarboxylic acid with a non‐aqueous mobile phase.
Synthesis and HPLC evaluation of carboxylic acid phases on a hydride surface
Authors: Pesek Joseph J. , Matyska Maria T. , Gangakhedkar Surekha , Siddiq Rukhsana
Published: March 2006

Three organic moieties containing carboxylic acid functional groups are attached to a particulate silica surface through silanization/hydrosilation. Two compounds (undecylenic acid and 10‐undecynoic acid) have 11 carbon chains and the other is a five‐carbon acid (pentenoic acid). Bonding is confirmed through carbon elemental analysis, diffuse reflectance infrared fourier transform spectroscopy, and carbon‐13 and silicon‐29 CP‐MAS NMR spectroscopy. The bonded phases are tested by HPLC using PTH amino acids, nucleic acids, theophylline‐related compounds, anilines, benzoic acid compounds, choline, and tobramycin. The latter two compounds are used to investigate the aqueous normal phase properties of the three bonded materials.
HPLC separation of fullerenes on two charge‐transfer stationary phases
Authors: Yu Qiong‐Wei , Shi Zhi‐Guo , Lin Bo , Wu Yan , Feng Yu‐Qi
Published: March 2006

Two charge‐transfer stationary phases were prepared by immobilizing p‐nitrobenzoic acid and naphthyl acetic acid onto silica. The nitrophenyl moiety and the naphthyl moiety were grafted to silica gel through the spacer of aminoalkyl silanes. The HPLC separation of C60, C70, and higher fullerenes on the new stationary phases was also studied. The influence of mobile phase and column temperature on the separation of C60 and C70 was examined, respectively. The retentions of C60 and C70 on the two stationary phases increased with decreasing toluene content in the mobile phase or with increasing column temperature. Higher fullerenes can be separated well using toluene as the mobile phase on the stationary phase of p‐nitrobenzoic acid‐bonded silica.
Immobilized polymeric stationary phases using metalized silica supports
Authors: Faria Anizio M. , Jardim Isabel C. S. F. , Collins Kenneth E. , Collins Carol H.
Published: March 2006

Immobilized presynthesized polymers on porous metalized (zirconized or titanized) silica particles as new stationary phases with improved chemical stability for RP‐HPLC are reviewed. The preparations using different polymers, such as poly(methyloctylsiloxane), poly(methyltetradecylsiloxane), and poly(butadiene), different immobilization steps (gamma radiation, thermal treatment, and microwave radiation), and the chromatographic performances of these phases for polar, apolar, acidic, and basic compounds are discussed. The stability of some of these stationary phases using alkaline mobile phases is also presented.
An overview of the chromatographic properties and stability of C18 titanized phases
Authors: Silva César R. , Collins Carol H. , Collins Kenneth E. , Airoldi Claudio
Published: March 2006

Phases based on titanized silicas are an alternative in the search for HPLC stationary phases with enhanced pH stability. This technology explores the chemical modification of the bare silica surface by grafting a titanium oxide layer with the objective of retarding the dissolution of the support in alkaline mobile phases, followed by C18 silanization. The present manuscript describes recent work on the development of chemically bonded titanized phases, including phases containing embedded urea groups, and phases prepared both in the absence and in the presence of a monolayer of water preadsorbed onto the bare silica. The advantages and disadvantages of these alternative C18 titanized phases are discussed, taking into account their chromatographic properties accessed by some common test procedures. Column lifetimes, measured by accelerated aging tests using aggressive conditions, such as high‐pH phosphate mobile phases and elevated temperature, are also discussed.
Twenty years of research on silica‐based chiral stationary phases
Authors: Cancelliere Giovanna , D'Acquarica Ilaria , Gasparrini Francesco , Maggini Michele , Misiti Domenico , Villani Claudio
Published: March 2006

This review provides an overview of twenty years of pioneering work (from 1985 to 2005) of our research group in the preparation and application of enantioselective packing materials for HPLC. After a brief introduction to the rational design of a new chiral stationary phase, a detailed presentation in chronological order of appearance in the literature is given of the currently developed repertoire of chiral stationary phases and their typical applications. Emphasis is placed on the different synthetic strategies exploited to obtain highly efficient, stable, and versatile chiral stationary phases.
Selfaction effects of femtosecond laser pulses in dye-doped
5CB liquid crystal
Authors: Gayvoronsky V , Yakunin S , Enikeeva V , Ozheredov I , Shkurinov A
Published: March 2006

Photoinduced changes of transmittance and refractive
index of 5CB nematic liquid crystal doped with anthraquinone dye
under the action of femtosecond laser pulses are studied. The
processes are considered in terms of strong interaction between
liquid crystal matrix and dye molecules that is demonstrated by
the example of fluorescence spectra.
Wavelength-tunable hollow-beam generation by a
photonic-crystal fiber
Authors: Hu M-L , Wang Ch-Y , Serebryannikov E E , Song Y-J , Li Y-F , Chai L , Dukel'skii K V , Khokhlov A V , Shevandin V S , Kondrat'ev Yu N , Zheltikov A M
Published: March 2006

A photonic-crystal fiber that supports only a few
guided modes is shown to allow the generation of a spectrally
isolated wavelength-tunable hollow beam, which is ideally suited
for optical trapping and laser tweezing.
Near-field probing of photonic crystal directional couplers
Authors: Volkov V S , Bozhevolnyi S I , Borel P I , Frandsen L H , Kristensen M
Published: March 2006

We report the design, fabrication and characterization of a photonic crystal directional coupler with a size of ∼20×20 μm2fabricated in silicon-on-insulator material. Using a scanning near-field optical microscope we demonstrate a high coupling efficiency for TM polarized light at telecom wavelengths. By comparing the near-field optical images recorded in and after the directional coupler area, the features of light distribution are analyzed. Finally, the scanning near-field optical microscope observations are found to be in agreement with the transmission measurements conducted with the same sample.
Research of protective action of ischemic preconditioning on components of blood serum at a brain ischemia by Raman spectroscopy method
Authors: Vlasova I M , Buravtcov D E , Dolmatova E V , Koshelev V B , Saletsky A M
Published: March 2006

The method of the Raman spectroscopy makes possible to detect the protective action of ischemic preconditioning (a brief series of short cycles of an ischemia - reperfusion before the prolonged ischemia) on a tissue of a brain at a total brain ischemia, as it was registered on reduction of damage of blood serum LDL after a total ischemia with preliminary preconditioning.
Poly(ε‐Caprolactone)/Chitin and Poly(ε‐Caprolactone)/Chitosan Blend Films With Compositional Gradients: Fabrication and Their Biodegradability
Authors: Honma Tomonori , Zhao Li , Asakawa Naoki , Inoue Yoshio
Published: March 2006

Summary: Poly(ε‐caprolactone) (PCL)/chitin and PCL/chitosan blend films with compositional gradients were successfully fabricated by a dissolution/diffusion method; that is, repeatedly pouring the PCL/chitin (or PCL/chitosan) blend solutions, with variable composition, onto polysaccharide layers. The compositional gradient structure in the resulting films was characterized by polarized optic microscopy, ATR‐FT‐IR and trans‐FT‐IR microscopic spectroscopy. Enzymatic degradability of the PCL/chitin and PCL/chitosan blend films with compositional gradients in the presence of lysozyme was compared with those of homogeneous films and two‐layer films. It was found that the degradation rate of PCL/chitin blend films with a compositional gradient was far lower than that of the neat chitin film, whereas the degradation rate of PCL/chitosan blend films with a compositional gradient was close to that of the neat chitosan film. The suppression of the chitosan crystallization, which accelerates the enzymatic degradation, at the surface of PCL/chitosan films with a compositional gradient was much more severe than that for PCL/chitin films with a compositional gradient.

Polarized optical microscopy micrographs of cross sections of (a) PI2lay, (b) PIgrad, (c) PO2lay, and (d) POgrad.

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Polarized optical microscopy micrographs of cross sections of (a) PI2lay, (b) PIgrad, (c) PO2lay, and (d) POgrad.
NMR Spectroscopy and MALDI‐TOF MS Characterisation of End‐Functionalised PVP Oligomers Prepared with Different Esters as Chain Transfer Agents
Authors: Ranucci Elisabetta , Ferruti Paolo , Annunziata Rita , Gerges Irini , Spinelli Giuseppe
Published: March 2006

Summary: Ester‐functionalised poly(1‐vinylpyrrolidin‐2‐one) (PVP) oligomers obtained by radical polymerisation in methyl propionate, diethyl malonate and diethyl 2‐methylmalonate were characterised by NMR spectroscopy, and MALDI‐TOF mass spectrometry. The chain‐transfer constants were determined as 5.54 × 10−4, 1.22 × 10−3 and 1.70 × 10−2, respectively, by measuring the variation of the number‐average molecular weight on conversion. These values were compared with those of methyl isobutyrate (1.65 × 10−3) and ethyl lactate (1.03 × 10−2), which had been previously determined. A clear dependence was found on the reactivity of the mobile hydrogen atoms α with the ester group. All of the macromolecules carried a single ester function. Therefore, the re‐initiation step by the CTA‐derived radicals overwhelmingly prevailed over initiation by the primary radicals.

MALDI‐TOF mass spectra of broad‐distribution, end‐functionalised PVP oligomers, analysed in an HCCA matrix. a): PVPL; MALDI molecular weights: $\overline M _{\rm n}$ = 3 465; $\overline M _{\rm w}$ = 3 891; polydispersity index = 1.12. b) PVPM; MALDI molecular weights: $\overline M _{\rm n}$ = 2 272; $\overline M _{\rm w}$ = 2 775; polydispersity index = 1.22.

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MALDI‐TOF mass spectra of broad‐distribution, end‐functionalised PVP oligomers, analysed in an HCCA matrix. a): PVPL; MALDI molecular weights: $\overline M _{\rm n}$ = 3 465; $\overline M _{\rm w}$ = 3 891; polydispersity index = 1.12. b) PVPM; MALDI molecular weights: $\overline M _{\rm n}$ = 2 272; $\overline M _{\rm w}$ = 2 775; polydispersity index = 1.22.
Cover Picture: Macromol. Biosci. 3/2006
Authors: Hayashi Shinya , Ohkawa Kousaku , Yamamoto Hiroyuki
Published: March 2006

Cover: The figure shows brush‐like calcite crystals formed in the presence of random (upper) and sequential (lower) polypeptides containing O‐phospho‐L‐threonine and aspartic acid. Further details can be found in the Full Paper by S. Hayashi, K. Ohkawa,* and H. Yamamoto on page 228.
Highly Branched Poly(arylene ether)s via Oligomeric A2 + B3 Strategies
Authors: Lin Qin , Unal Serkan , Fornof Ann R. , Yilgor Iskender , Long Timothy E.
Published: March 2006

Summary: Branched poly(arylene ether)s were prepared in an oligomeric A2 + B3 polymerization of phenol endcapped telechelic poly(arylene ether sulfone) oligomers as A2 and TFPPO as trifunctional monomer B3. The molar mass of the A2 oligomer significantly influenced the onset of gelation and the DB. A high level of cyclization during polymerization of low molar mass A2 oligomers (U3 = 660 and U6 = 1 200 g · mol−1) led to a high conversion of functional groups in the absence of gelation, and the level of cyclization reactions in the polymerization decreased as the molar mass of the A2 oligomer was increased. The pronounced steric effect in the polymerization of higher molar mass A2 oligomers (U8 = 1 800 and U16 = 3 400 g · mol−1) resulted in low reactivity of the third aryl fluoride in the B3 monomer. As a result, only slightly branched (U8 = 1 800 g · mol−1) or nearly linear (U16 = 3 400 g · mol−1) high molar mass products were obtained with higher molar mass A2 oligomers. The branched polymers exhibited lower Mark‐Houwink exponents and [η] relative to linear analogs, and differences between the branched polymers and linear analogs were less significant as the molar mass of the A2 oligomers was increased due to a decrease in the overall DB.

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Stabilizer‐Free Dispersion Copolymerization of Maleic Anhydride and Vinyl Acetate. II. Polymerization Features
Authors: Xing Chang‐Min , Yu Yong , Yang Wan‐Tai
Published: March 2006

Summary: The polymerization features of the novel stabilizer‐free dispersion copolymerization of MAn and VAc were studied. It was found that the dispersion copolymerization of MAn/VAc is a fairly rapid process, which starts from a slow solution polymerization (below 10% conversion, Stage I) and follows a drastic increase of polymerization rate (10–80% conversion, Stage II) due to the known gel effect. Such process was accompanied by the increase of molecular weight of the copolymer formed ($\overline M _{\rm n}$ from 1.2 × 104 to 3.8 × 104 g · mol−1) and the broadening of the molecular weight distribution ($\overline M _{\rm w} /\overline M _{\rm n}$ from 2.4 to 8.0). Ea of Stage I was determined to be 76.7 kJ · mol−1, while the value of Stage II was 64.7 kJ · mol−1. The lower Ea in Stage II than that in Stage I suggests that there exists a shift of polymerization locus from the solution phase to the particle phase. Moreover, we found that the initial rate of polymerization increased with monomer concentration as well as initiator concentration, following the relationship (Rp)i ∝ [MAn + VAc] · [BPO]. This further implies that the dispersion copolymerization mainly proceeds as a solution polymerization in the very early stage.

Evolutions of the stabilizer‐free dispersion copolymerization of MAn and VAc with butyl acetate as reaction medium and the solution copolymerization with methyl propyl ketone as solvent.

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Evolutions of the stabilizer‐free dispersion copolymerization of MAn and VAc with butyl acetate as reaction medium and the solution copolymerization with methyl propyl ketone as solvent.
Nanosized‐Silica‐Reinforced Holographic Polymer‐Dispersed Liquid Crystals
Authors: Kim Eun Hee , Woo Ju Yeon , Kim Byung Kyu
Published: March 2006

Summary: Nanosized silicas added to holographic polymer‐dispersed liquid crystals (HPDLC) provide the resin phase with increased elasticity, dimensional stability, and the high diffraction efficiency of the gratings. On the other hand, nucleation and growth of periodic modulation are delayed, especially with small‐sized silica because of the increased viscosity of the resin mixture. Effects of the LC/resin composition and cell gap on the diffraction efficiency have also been studied.

AFM image of silica added HPDLC.

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AFM image of silica added HPDLC.
Kinetic Studies upon the Influence of Cyclodextrin on the Polymerization of Methacrylamides in Homogenous Aqueous Solution
Authors: Steffens Christopher , Choi Soo Whan , Ritter Helmut
Published: March 2006

Summary: N‐methacryloyl‐1‐aminopropane (1), N‐methacryloyl‐1‐aminobutane (2), N‐methacryloyl‐1‐aminopentane (3), and N‐methacryloyl‐1‐aminohexane (4) are synthesized and treated with an aqueous solution of randomly methylated β‐cyclodextrin (Me‐β‐CD) to form the water‐soluble host‐guest complexes 1a–4a. In case of the aqueous polymerization of the free monomers 1–4 the initial polymerization rate increases with increasing water solubility. The opposite effect is observed in the case of the polymerizations of the Me‐β‐CD‐complexed methacrylamide monomers 1a–4a. The polymerization rates are increased with increasing alkyl chain length of the complexed monomers 1a–4a and decreasing water solubility of the free monomers 1–4.

Initial polymerization rate v0 of CD‐complexed monomers 1a–4a (○) vs. water solubilities of monomers 1–4 (▪).

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Initial polymerization rate v0 of CD‐complexed monomers 1a–4a (○) vs. water solubilities of monomers 1–4 (▪).
Poly(dicyclopentadiene) Submicron Fibers Produced by Electrospinning
Authors: Bellan Leon M. , Coates Geoffrey W. , Craighead Harold G.
Published: March 2006

Summary: We have used the process of electrospinning to produce fibers of poly(dicyclopentadiene) with diameters on the submicron scale. The material, formed from a monomer‐catalyst solution, polymerized in flight during the electrospinning process. Fibers were collected over trenches etched in silicon and the Young's moduli were measured using an atomic force microscope to measure force‐displacement curves. The resulting values of Young's moduli are larger than typical values for bulk polymer material.

SEM image of suspended PDCPD fiber.

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SEM image of suspended PDCPD fiber.
Synthesis and Characterization of Novel pH‐Responsive Polyampholyte Microgels
Authors: Tan Beng Hoon , Ravi Palaniswamy , Tam Kam Chiu
Published: March 2006

Summary: We synthesized for the first time novel pH‐responsive polyampholyte microgels consisting of poly(methacrylic acid) and poly(2‐(diethylamino)ethyl methacrylate) (PMAA‐PDEA) that are sterically stabilized with poly(ethylene glycol) methyl ether methacrylate (PEGMEM). These microgels showed enhanced hydrophilic behavior in aqueous medium at low and high pH but become hydrophobic and compact between pH 4 and 6 near the isoelectric point. Dynamic‐light scattering measurements showed that the hydrodynamic radius, Rh of these microgels is approximately 100 nm between pH 4 and 6 and increases to around 140 and 170 nm at pH 2 and 10, respectively. It is evident that the cross‐linked MAA‐DEA microgel that is sterically stabilized with PEGMEM retains the polyampholyte properties in solution.

Sterically stabilized cross‐linked MAA‐DEA microgel.

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Sterically stabilized cross‐linked MAA‐DEA microgel.
Confocal Raman Microspectroscopy: Calculation of Corrected Depth Profiles of Wet‐Chemically Modified Polymer Films
Authors: Gallardo Alberto , Spells Stephen , Navarro Rodrigo , Reinecke Helmut
Published: March 2006

Summary: A mathematical approach developed to correct depth profiles of wet‐chemically modified polymer films obtained by confocal Raman microscopy is presented which takes into account scattered contributions originated from a diffraction‐limited laser focal volume and the refractive index of the sample. The method is demonstrated in both virtual and real samples where it is shown that considerable differences between apparent and corrected depth profiles exist at the surface, especially when profiles with strong concentration gradients are dealt with or an instrument with poor depth resolution is used.

Comparison of depth profiles obtained by simple normalization (solid line) and normalization after correction of the data with respect to diffraction effects.

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Comparison of depth profiles obtained by simple normalization (solid line) and normalization after correction of the data with respect to diffraction effects.
Thermal and Surface Properties of Phenolic Nanocomposites Containing Octaphenol Polyhedral Oligomeric Silsesquioxane
Authors: Lin Han‐Ching , Kuo Shiao‐Wei , Huang Chih‐Feng , Chang Feng‐Chih
Published: March 2006

Summary: We have synthesized a new polyhedral oligomeric silsesquioxane (POSS) containing eight phenol functional groups and copolymerized it with phenol and formaldehyde to form novolac‐type phenolic/POSS nanocomposites exhibiting high thermal stabilities and low surface energies. Our DSC results indicate that the glass transition temperature of these nanocomposites increased initially upon increasing their POSS content, but then decreased at POSS content above 10 wt.‐%, presumably because of the formation of relatively low molecular weight species and POSS aggregation as evidenced from MALDI‐TOF mass analyses. Our TGA analyses indicated that the 5‐wt.‐%‐mass‐loss temperatures (Td) increased significantly upon increasing the POSS content because the incorporation of the POSS led to the formation of an inorganic protection layer on the nanocomposite's surface. XPS and contact angle data provided positive evidence to back up this hypothesis. In addition, contact angle measurements indicated a significant enhancement in surface hydrophobicity after increasing the POSS content.

Syntheses procedures of phenolic/OP‐POSS nanocomposites.

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Syntheses procedures of phenolic/OP‐POSS nanocomposites.
Preparation of Well‐Defined PVOH/C60 Nanohybrids by Cobalt‐Mediated Radical Polymerization of Vinyl Acetate
Authors: Detrembleur Christophe , Stoilova Olya , Bryaskova Rayna , Debuigne Antoine , Mouithys‐Mickalad Ange , Jérôme Robert
Published: March 2006

Summary: Poly(vinyl acetate) chains end‐capped by a Co(acac)2 complex [PVAc‐Co(acac)2] were prepared by bulk cobalt‐mediated radical polymerization (CMRP) of vinyl acetate and used for grafting fullerene (C60) with four PVAc arms at low temperature (30 °C). A photoactive water‐soluble poly(vinyl alcohol)/C60 nanohybrid was then prepared by hydrolysis of the PVAc arms of the nanohybrid. Because of photoactivity and very low cytotoxicity, this type of water‐soluble nanohybrid is very promising for the photodynamic cancer therapy.

Strategy for the preparation of PVAc/C60 nanohybrid and hydrolysis of PVAc/C60 nanohybrid into PVOH/C60 nanohybrid.

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Strategy for the preparation of PVAc/C60 nanohybrid and hydrolysis of PVAc/C60 nanohybrid into PVOH/C60 nanohybrid.
Micro FTIR Mapping of Nanometer Ferroelectric Polymer Films
Authors: Eidelman Naomi , Tsutsumi Naoto , Chiang Chwan‐Kang
Published: March 2006

Summary: Highly crystalline ferroelectric polymer films [vinyidene fluoride and trifluoroethylene, β‐P(VDF‐TrFE), 260–15 nm thick] were characterized with FTIR reflectance‐transmission microspectroscopy (FTIR‐RTM) mapping technique (400 µm × 400 µm spatial resolution). The amorphous and crystalline fractions were identified locally. FTIR‐RTM maps (1 cm2 area) provided a unique in‐depth view of the ultrathin films. Lower film thickness suppressed growth of the crystalline phase. Increased content of amorphous phase lead to non‐uniform films with degraded ferroelectric behavior.

FTIR‐RTM maps of the distribution of the amorphous phase in the 80 and 35 nm films.

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FTIR‐RTM maps of the distribution of the amorphous phase in the 80 and 35 nm films.
Synthesis of Novel Biomimetic Zwitterionic Phosphorylcholine‐Bound Chitosan Derivative
Authors: Zeng Rong , Fu Hua , Zhao Yufen
Published: March 2006

Summary: Water‐soluble biomimetic chitosan derivative conjugating zwitterionic phosphorylcholine was efficiently prepared through Atherton‐Todd reaction under the mild conditions, and the possible formation mechanism of zwitterionic product was related to the nucleophilic attack of adjacent 3‐hydroxyl on the D‐glucosamine residue to phosphorus with the help of base. UV absorption and melting behaviors of DNA/phosphorylcholine‐bound chitosan derivative showed that the phosphorylcholine‐bound chitosan derivative could be a new carrier for long‐circulating macromolecular drug delivery.

Structure of zwitterionic PC‐chitosan.

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Structure of zwitterionic PC‐chitosan.
Prediction of Chemical‐Physical Properties by Neural Networks for Structures
Authors: Duce Celia , Micheli Alessio , Solaro Roberto , Starita Antonina , Tiné Maria Rosaria
Published: March 2006

Here we present an overview of a new approach to cheminformatics based on recursive neural networks. This approach allows for combining the flexibility and advantages of neural networks with the representational power of structured domains. Current advances, which include applications to the prediction of the solvation free energy of small molecules in water and of the glass transition temperature of (meth)acrylic polymers are reported.
Biodegradable Fibers of Poly‐L, DL‐lactide 70/30 Produced by Melt Spinning
Authors: Fambri Luca , Bragagna Stefano , Migliaresi Claudio
Published: March 2006

Melt spinning of poly‐L, DL‐lactide 70/30 has been studied. Fiber having diameter lower than 120 micron exhibited tensile modulus and strength in the range of 3–4 GPa and 130–180 MPa, respectively. Maximum attainable modulus and strength of 4.7 GPa and 205 MPa were predicted, according to a proposed equation in dependence on the draw ratio. In vitro degradation performed in PBS solution at 37 °C, showed that after 4 weeks fibers maintained adequate properties for tissue engineering applications.
PLLA Based Composites with α‐Tricalcium Phosphate and a PLLA‐PEO Diblock Copolymer
Authors: Bigi Adriana , Boanini Elisa , Maglio Giovanni , Malinconico Mario , Palumbo Rosario , Scafati Santolo Taglialatela
Published: March 2006

Hybrid composites consisting of poly(L‐lactide), PLLA, or blends of PLLA with a PLLA‐poly(ethylene oxide) diblock copolymer (15–30 wt%), COP, as a biodegradable polymeric matrix and of bioactive α‐tricalcium phosphate, α‐TCP, microparticles as dispersed phase (25–40 wt‐%) were prepared by melt extrusion and their thermal, mechanical and degradation behaviour was investigated. SEM analysis of surfaces broken in liquid N2 showed a good dispersion of α‐TCP in the polymer matrix. A lowering of the glass transition temperature of the polymer matrix and enhanced crystallization rates of PLLA, both from the melt and from the glassy state, were observed in the presence of COP. Ternary PLLA/COP/α‐TCP composites containing about 10 wt‐% of COP and 25–40 wt‐% of α‐TCP showed improved compressive strength and deformation at yield as compared to pure PLLA. Degradation experiments revealed that in simulated body fluid the presence of α‐TCP particles promoted the formation of inorganic deposits of a poor crystalline apatitic phase on composite surfaces as compact sferoids.
A Novel Route to Graft‐Copolymers with Tailored Structures for the Compatibilization of Polymeric Blend
Authors: Caporaso Lucia , Iudici Nicola , Oliva Leone
Published: March 2006

A new method to synthesize graft‐copolymers based on isotactic polypropylene (iPP) with tailored structure has been developed. The synthesis is a two‐step process: synthesis of P‐co‐(p‐MS‐E) copolymers, by using ansa‐metallocene catalysts, and metallation of p‐Me groups followed by living anionic polymerisation for the graft growth. This method turn out to be versatile because, by changing experimental conditions, in the first step backbones with a tuned number of the graft growth sites and polypropylene lengths can be obtained, whereas in the second step, graft chains of different types and lengths can be synthesized. The particular ability of these copolymers to compatibilize polymeric blends was evaluated analyzing the morphology of the products copolymers/blends by using a scanning electron microscopy (SEM).
Synthesis of Energetic Polyethers from Halogenated Precursors
Authors: Barbieri Ugo , Polacco Giovanni , Massimi Roberto
Published: March 2006

In the solid rocket propellant formulations an important component is the polymeric binder. Actually, the most used binder is hydroxyl‐terminated polybutadiene. However, the research is oriented toward the use of energetic polymers which, in addition to the binder function, should improve the propulsion capability of the propellant. In this respect, good candidates are oxetanic polyethers with azidic functionalities in their side chains. Considering the explosive character of such materials, their synthesis must be designed with attention to the safety of the process. In this note, the preparation of azidic copolymers is described and different synthetic strategies are discussed and compared.
Polypropylene‐POSS Nanocomposites: Morphology and Crystallization Behaviour
Authors: Pracella Mariano , Chionna Donatella , Fina Alberto , Tabuani Daniela , Frache Alberto , Camino Giovanni
Published: March 2006

Nanocomposites of isotactic polypropylene (PP) with polyhedral oligomeric silsesquioxanes (POSS) [RSiO1,5]8 having different alkyl substituents (R = methyl, isobutyl, isooctyl) were obtained by melt blending and analysed with electron microscopy, optical microscopy and DSC calorimetry. The influence of POSS structure on the morphological characteristics, the crystallization and melting behaviour of PP/POSS composites was investigated with varying the filler amount. The crystallization kinetics of the composites from the melt, examined both in isothermal and non‐isothermal conditions, demonstrated that the nucleation activity of the examined POSS can be related to the length of alkyl substituents which, depending on the loading amount, affect the filler dispersion in the PP matrix and the growth of polymer crystals.
Novel Thiophenic Copolymer as a Multi‐Purpose Macromolecular Intermediate
Authors: Paganin Luisa , Costa‐Bizzarri Paolo , Lanzi Massimiliano , Cesari Gaia , Bertinelli Franco , Cagnoli Rita , Mucci Adele
Published: March 2006

The preparation of a new thiophenic dimer partially derivatized with a bromohexylic chain is described. Its polymerization under mild oxidative conditions leads to a polythiophene with a degree of functionalization of 50% and highly soluble in organic solvents. The product has been fully characterized by FT‐IR, 1H and 13C NMR using one and two‐dimensional techniques as well as by SEC and thermal analysis. Solvatochromic effects of the new polymer have been investigated in different mixtures, underlining its self‐assembling capability even in solvated states.
Ligands Tethering to Biocompatible Ultrasound Active Polymeric Microbubbles Surface
Authors: Cavalieri Francesca , Hamassi Ali El , Chiessi Ester , Paradossi Gaio , Villa Raffaella , Zaffaroni Nadia
Published: March 2006

Ultrasound imaging, also known as echography, is a widespread diagnostic tool in medicine. Handiness and versatility are established assets of this non‐invasive imaging technique. Echogenic devices enhance the sensitivity of this method and formulations of novel systems is a growing field in biomedical research. In this contribution we describe the synthesis, the mesoscopic characterization, and the functionalization of microbubbles based on telechelic poly (vinyl alcohol) for a next‐generation ultrasound imaging multifunctional device suitable for diagnosis as well as for therapeutic purposes.
Oriented Nanoporous Host δ Phases of Syndiotactic Polystyrene as a Tool for Spectroscopic Investigation of Guest Molecules
Authors: Albunia Alexandra R. , Grassi Alfonso , Milano Giuseppe , Rizzo Paola , Venditto Vincenzo , Musto Pellegrino , Guerra Gaetano
Published: March 2006

An efficient method to align low‐molecular‐mass molecules by enclosing them as isolated guests of the nanoporous host δ phase of syndiotactic polystyrene oriented films, is presented. This new method is compared with the classic method consisting in the absorption of low‐ molecular‐mass molecules as a solute of amorphous phases of highly oriented semicrystalline polymeric films. It is shown that this new molecular alignment method provides a powerful tool to study in detail several features (spectroscopic properties, molecular motions) of relevant molecules, by separating with unprecedented selectivity their anisotropic spectral responses. The reported results refer to infrared and solid‐state‐2H‐NMR spectra.
Structure and Properties of a Polypropylene Containing Random Ethylene Units Modified with a Hydrogenated Hydrocarbon Resin
Authors: Cimmino Sossio , Duraccio Donatella , Silvestre Clara
Published: March 2006

The system formed by a polypropylene containing random low ethylene content (EP copolymer) of and a hydrogenated hydrocarbon resin (HR) is investigated in order to study the influence of resin (up to 20% in wt) on properties of blends and derived films. The random EP copolymer used is MoplenEP2C37F and the resin is MBG273 of Hercules Chemical Co. DSC and DMTA analyses of the blends show increase of Tg with resin content indicating that the two components are compatible in the amorphous phase. WAXD spectra show that MBG273 influences slightly the crystalline structure of EP copolymer. In fact the diffractograms of the EP copolymer and 95/5 blend present, beside the predominant peak of α form, also a small span denoting presence of γ form; this span is not detectable on spectra of 90/10 and 80/20 samples. The crystallization during the cooling is found to be only lightly delayed by the HR: in fact, only 4 degrees is the difference between the Tc values of EP copolymer and 80/20 blend. Stress‐strain test performed at room temperature show that MBG273 induces increase of Young's modulus and small decrease of elongation at break as function of resin content. An important effect is on the water vapour permeability, which decreases with resin content. The permeability and tensile properties are related to the increase of the glass transition with the addition of MBG273 that transforms gradually the amorphous of the material from rubbery to glassy. The results reported in this work indicate that an addition of 5–10% of MBG273 changes favourably properties, as Young' modulus and water vapour permeability, of an EP copolymer designed for the production of films for packaging application.
rac‐[CH2(3‐tert‐butyl‐1‐indenyl)2]ZrCl2/MAO in the Copolymerization of Olefins and Dienes
Authors: Pragliola Stefania , Costabile Chiara , Napoli Mariagrazia , Guerra Gaetano , Longo Pasquale
Published: March 2006

Olefin‐diene copolymerizations in the presence of C2 symmetric zirconocene rac‐[CH2(3‐tert‐butyl‐1‐indenyl)2]ZrCl2/MAO catalytic system have been reported and rationalized by experimental and molecular modeling studies. Ethene gives 1,2‐cyclopropane and 1,2‐cyclopentane, 1,3‐cyclobutane, and 1,3‐cyclopentane units in copolymerization with 1,3‐butadiene, 1,4‐pentadiene, and 1,5‐hexadiene, respectively. Propene‐1,3‐butadiene copolymerizations lead to 1,2 and 1,4 butadiene units and to a low amount of 1,2‐cyclopropane units.
On the Bulk Properties of a Poly(Bicycloacrylate) Carrying Semifluorinated Side Groups
Authors: Martinelli Elisa , Domenici Valentina , Ragnoli Marina , Moszner Norbert , Galli Giancarlo
Published: March 2006

We prepared a novel fluorinated polymer from a bicycloacrylate monomer, (1H,1H,2H,2H)‐perfluorododecyl 2‐(bicyclo[3.1.0]hex‐1‐yl)acrylate, by radical ring opening polymerization. The bulk properties of the polymer were investigated by thermal analysis and X‐ray diffraction, which proved the existence of a smectic mesophase up to the isotropization temperature of 74 °C. Furthermore, a solid state NMR study was started to characterize domains with different mobility mainly by 13C cross‐polarization magic angle spinning and T2 selective experiments. We found that the polymer is a homogeneous sample with the presence of dynamic motions in the kHz regime below the glass transition temperature.
Nanocomposite Fibers for Cosmetotextile Applications
Authors: Persico Paola , Carfagna Cosimo , Musto Pellegrino
Published: March 2006

In this work, a series of nylon 6 nanocomposites with different nanoclay/jojoba oil contents have been prepared by direct melt compounding. Nanocomposite morphologies were characterized by means of WAXS analysis. Thermal and mechanical fibers properties were studied as well. The kinetic desorption of the cosmetic oil through the polymer matrix was evaluated by FT‐IR microscopy. It was found that the state of the clay particles affected the thermal behaviour and the tensile mechanical properties of each polymer/clay hybrid. On the other hand, the release of the cosmetic oil, tested by FT‐IR microscopy, is a good perspective for the application of polyamide 6 nanocomposite fibers as textiles in cosmetic field.