bluuebunny/crossref_metadata_2025 huggingface dataset:
Oral squamous cell carcinoma and a clinically negative neck: The value of follow‐up
Authors: Wensing Bart M. , Merkx Matthias A. W. , Krabbe Paul F. M. , Marres Henri A. M. , Van den Hoogen Frank J. A.
Published: November 2010

Background

In squamous cell carcinoma of the oral cavity (SCCOC), regular follow‐up comprises 5 years of prescheduled visits, irrespective of tumor stage/classification and/or treatment. We analyzed our standard treatment and follow‐up protocol in patients with a preoperative clinically negative neck (cN0) in SCCOC.

Methods

This is a retrospective chart analysis. Inventarization of treatment, occult metastatic spread, and follow‐up were performed.

Results

In all, 197 patients were included. The occult metastatic rate was 24%. Eighty‐three percent of recurrent disease presented within 2 years. Fifty‐three percent of the patients with recurrent disease visited their physician outside prescheduled control visits.

Conclusions

Ultrasound‐guided fine‐needle aspiration cytology currently is 1 of the most reliable staging techniques in cN0 SCCOC. Regular follow‐up could perhaps be limited from 5 to 2 years of prescheduled follow‐up visits. © 2010 Wiley Periodicals, Inc. Head Neck, 2010
Regulation of mammalian muscle type 6‐phosphofructo‐1‐kinase and its implication for the control of the metabolism
Authors: Sola‐Penna Mauro , Da Silva Daniel , Coelho Wagner S. , Marinho‐Carvalho Monica M. , Zancan Patricia
Published: November 2010

Phosphofructokinase (PFK) is a major regulatory glycolytic enzyme and is considered to be the pacemaker of glycolysis. This enzyme presents a puzzling regulatory mechanism that is modulated by a large variety of metabolites, drugs, and intracellular proteins. To date, the mammalian enzyme structure has not yet been resolved. However, it is known that PFK undergoes an intricate oligomerization process, shifting among monomers, dimers, tetramers, and more complex oligomeric structures. The equilibrium between PFK dimers and tetramers is directly correlated with the enzyme regulation, because the dimer exhibits very low catalytic activity, whereas the tetramer is fully active. Several PFK ligands modulate the enzyme, favoring the formation of its dimers or tetramers. The present review integrates recent findings regarding the regulatory aspects of muscle type PFK and discusses their relation to the control of metabolism. © IUBMB IUBMB Life, 62(11): 791–796, 2010.
Functional nonequivalence of transketolase active centers
Authors: Kochetov German A. , Sevostyanova Irina A.
Published: November 2010

Transketolase (TK, EC 2.2.1.1), the key enzyme of the non‐oxidative branch of pentose phosphate pathway of hydrocarbon transformation, plays an important role in a system of substrate rearrangement between pentose shunt and glycolysis, acting as a reversible link between the two metabolic pathways. In addition, it supplies precursors for biosyntheses of nucleotides, aromatic amino acids, and vitamins. In plants, the enzyme plays a central role in the Calvin cycle. TK catalyzes interconversion of sugar phosphates. Thiamine diphosphate (TDP) and bivalent cations serve as its cofactors. Being a typical TDP‐dependent enzyme, TK is the least complex representative of this group of enzymes, and this accounts for its use as a model in studies of their structure and mechanism of action. TK is readily crystallized, this being the reason why the first crystal X‐ray structure analysis of TDP‐dependent enzymes was performed with a TK sample. Both the general structure of TK and the structures of its active centers have been studied in detail. In this article, we review experimental evidence of functional nonequivalence of the two active centers of TK, which are known to be identical by crystal X‐ray structure analysis. © IUBMB IUBMB Life, 62(11): 797–802, 2010.
Increased female fertility in aquaporin 8‐deficient mice
Authors: Su Weiheng , Qiao Ying , Yi Fei , Guan Xingang , Zhang Di , Zhang Shuzhi , Hao Feng , Xiao Yinghong , Zhang Hongguo , Guo Lei , Yang Longfei , Feng Xuechao , Ma Tonghui
Published: November 2010

Aquaporin‐8 (AQP8) is a water channel expressed extensively in male and female reproductive systems. But its physiological functions are largely unknown. In the present study, we first found significantly increased number of offspring delivered by AQP8−/− mothers compared with wild‐type mothers in cross‐mating experiments. Comparison of ovulation in the two genotypes demonstrated that AQP8−/− ovaries released more oocytes (9.5 ± 1.9 vs. 7.1 ± 2.1 in normal ovulation and 37.8 ± 6.7 vs. 27.9 ± 5.7 in superovulation). Histological analysis showed increased number of corpus luteums in mature AQP8−/− ovaries, suggesting increased maturation and ovulation of follicles. By RT‐PCR, western blot and immunohistochemistry analyses, we determined the expression of AQP8 in mouse ovarian granulosa cells. Granulosa cells isolated from AQP8−/− mice showed 45% of decreased membrane water permeability than wild‐type mice. As the atresia of ovarian follicles is primarily due to apoptosis of granulosa cells, we analyzed the apoptosis of isolated granulosa cells from wild‐type and AQP8−/− mice. The results indicated significantly lower apoptosis rate in AQP8−/− granulosa cells (21.3 ± 3.6% vs. 32.6 ± 4.3% in AQP8+/+ granulosa cells). Taken together, we conclude that AQP8 deficiency increases the number of mature follicles by reducing the apoptosis of granulosa cells, thus increasing the fertility of female mice. This discovery may offer new insight of improving female fertility by reducing granulosa cell apoptosis through AQP8 inhibition. © IUBMB IUBMB Life, 62(11): 852–857, 2010.
Mechanical properties of cross‐linked collagen meshes after human adipose derived stromal cells seeding
Authors: Ochoa Ignacio , Peña Estefania , Andreu Enrique J. , Pérez‐Ilzarbe Maitane , Robles Jose E. , Alcaine Clara , López Tania , Prósper Felipe , Doblaré Manuel
Published: November 2010

The main goal of this study was to evaluate the potential of collagen meshes derived from porcine dermis as scaffolds for repairing pelvic organ prolapses. Mechanical properties of collagen meshes with different cross‐linking percentages before and after Adipose Derived Stromal Cells (ADSC) seeding were studied as well as the cell‐scaffold interaction. Uniaxial tensile tests of the collagen meshes with three different cross‐linking percentages (full‐, partial‐, and noncross‐linked) were carried out along orthogonal directions. Their mechanical properties were studied with the same tests before and after seeding with human derived adipose stem cells (ADSC) after 1 and 7 days. Histological analyses were performed to determine adhesion and proliferation of ADSC. Significant differences in mechanical properties of the unseeded meshes were observed between each orthogonal direction independently of the cross‐linking percentage. A better cell adhesion rate was observed in the cross‐linked meshes. An increase in the mechanical properties after cell seeding was observed with a direct relation with the degree of cross‐linking. All meshes analyzed showed a marked anisotropy that should be taken into account during the surgical procedure. The cross‐linking treatment increased cell adhesion and the mechanical properties of the collagen meshes after seeding. These results suggest that the mechanical properties of this type of collagen mesh could be useful as scaffolds for repair of pelvic organ prolapse. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.
Suppression of HIV‐1 transcriptional elongation by a DING phosphatase
Authors: Darbinian Nune , Gomberg Rebeccah , Mullen Loriann , Garcia Samantha , White Martyn K. , Khalili Kamel , Amini Shohreh
Published: November 2010

HIV‐1 gene transcription is controlled by the cooperation of viral and host factors which bind to specific DNA sequences within the viral promoter spanning the long terminal repeat (LTR). Previously we showed that the St. John's Wort DING phosphatase, p27SJ, suppresses HIV‐1 gene transcription by binding to the viral protein Tat and preventing its nuclear import. Here, we describe the inhibitory effect of p27SJ on the phosphorylation of the C‐terminal domain (CTD) of RNA polymerase II (RNAPII). This inhibition leads to the suppression of the association of RNAPII with the LTR. Inhibition of binding of RNAPII to LTR by p27SJ resulted in the suppression of LTR transcription elongation and a decrease in LTR transcriptional activity. Another form of the St. John's Wort DING phosphatase, p38SJ, also suppressed binding of RNAPII to the LTR, reduced transcription elongation and was even more powerful than p27SJ in inhibiting the transcriptional activity of the LTR. Our data suggest a possible mechanism by which the p27SJ/p38SJ DING phosphatase can regulate HIV‐1 LTR expression by inhibiting phosphorylation of the CTD of RNAPII and suppressing LTR transcription elongation. J. Cell. Biochem. 112: 225–232, 2011. © 2010 Wiley‐Liss, Inc.
Spin‐driven activation of dioxygen in various metalloenzymes and their inspired models
Authors: De La Lande Aurelien , Salahub Dennis R. , Maddaluno Jacques , Scemama Anthony , Pilme Julien , Parisel Olivier , Gerard Helene , Caffarel Michel , Piquemal Jean‐Philip
Published: November 2010

Although potentially powerful, molecular oxygen is an inert oxidant due to the triplet nature of its ground state. Therefore, many enzymesse various metal cations (M) to produce singlet active species MnO2. In this communication we investigate the topology of the Electron Localization Function (ELF) within five biomimetic complexes which are representative of the strategies followed by metalloenzymes to activate O2. Thanks to its coupling to the constrained DFT methods the ELF analysis reveals the tight connection between the spin state of the adduct and the spatial organization of the oxygen lone pairs. We suggest that enzymes could resort to spin state control to tune the regioselectivity of substrate oxidations. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011
On easy implementation of a variant of the replica exchange with solute tempering in GROMACS
Authors: Terakawa Tsuyoshi , Kameda Tomoshi , Takada Shoji
Published: November 2010

To reduce the number of replicas required in the conventional replica exchange method for huge systems, recently the replica exchange with solute tempering (REST) method was proposed. Here we showed that a variant of REST realized by rescaling the force‐field parameters can be performed with GROMACS 4 without changing the code. We tested the variant REST for alanine dipeptide and an N‐terminal peptide from p53 confirming its performance nearly equal to the original REST. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011
Density functional study of structural, electronic, and optical properties of small bimetallic ruthenium‐copper clusters
Authors: Karagiannis Efstathios E. , Kefalidis Christos E. , Petrakopoulou Ioanna , Tsipis Constantinos A.
Published: November 2010

The structural, electronic, bonding, magnetic, and optical properties of bimetallic [CunRum]+/0/− (n + m ≤ 3; n, m = 0–3) clusters were computed in the framework of the density functional theory (DFT) and time‐dependent DFT (TD‐DFT) using the full‐range PBE0 nonlocal hybrid GGA functional combined with the Def2‐QZVPP basis sets. Several low‐lying states have been investigated and the stability of the ground state spinomers was estimated with respect to all possible fragmentation schemes. Molecular orbital and population analysis schemes along with computed electronic parameters illustrated the details of the bonding mechanisms in the [CunRum]+/0/− clusters. The TD‐DFT computed UV–visible absorption spectra of the bimetallic clusters have been fully analyzed and assignments of all principal electronic transitions were made and interpreted in terms of contribution from specific molecular orbital excitations. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011
Fast calculation of DNMR spectra on CUDA‐enabled graphics card
Authors: Szalay Zsófia , Rohonczy János
Published: November 2010

During the past few years, general‐purpose graphics processing units (GPGPUs) have become rather popular in the high performance computing community. In this study, we present an implementation of the simulation of dynamic nuclear magnetic resonance (DNMR) spectra. The algorithm is based on the kinetic Monte Carlo method and therefore can benefit from the multithreaded architecture of the GPGPU. By careful optimization of the algorithm a 30–100‐fold speed increase could be achieved. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011
Implementation of CBT for youth affected by the World Trade Center disaster: Matching need to treatment intensity and reducing trauma symptoms
Authors:   CATS Consortium
Published: November 2010

An implementation study of cognitive–behavioral therapies (CBT) was conducted for traumatized youth in a postdisaster context. Headed by the New York State Office of Mental Health, the study targeted youth (N = 306) ages 5–21 affected by the World Trade Center disaster. They received either trauma‐specific CBT or brief CBT skills depending upon the severity of trauma symptoms. Clinicians were trained to deliver these interventions and received monthly consultation. A regression discontinuity design was used to assess optimal strategies for matching need to service intensity. At 6‐months postbaseline, both groups had improved. Rate of change was similar despite differences in severity of need. The implications for the implementation of evidence‐based treatments postdisaster are discussed.
Electrospinning of Poly[acrylonitrile‐co‐(glycidyl methacrylate)] Nanofibrous Mats for the Immobilization of Candida Antarctica Lipase B
Authors: Dai Tianhe , Miletić Nemanja , Loos Katja , Elbahri Mady , Abetz Volker
Published: November 2010

PANGMA nanofibers and nanomats with fiber diameters of 200–300 nanometers were fabricated by electrospinning. Cal‐B was covalently immobilized onto the PANGMA nanomats via three different immobilization routes. The properties of the Cal‐B‐immobilized PANGMA nanomats were assayed and compared with the free Cal‐B. The observed Cal‐B loading on these nanomats is up to ≈50 mg · g−1, and their hydrolytic activity is up to ≈2 500 nmol · min−1 · mg−1, much higher than free enzyme powder and also slightly higher than Novozyme 435. Cal‐B immobilized PANGMA nanomats have better reusability, thermal stability, and storage ability than free Cal‐B. They retain over 50% of their initial activity after 15 cycles, over 65% after 10 h heat incubation, and over 75% after 30 d storage.

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Radiation Induced Double Grafting of Polybutadiene Olygomers and Styrene onto Silica: Characterization of the Materials and Mechanistic Studies
Authors: Dondi Daniele , Palamini Claudia , Buttafava Armando , Faucitano Antonio , Galinetto Pietro , Nahmias Marco , Giannini Luca , Lostritto Angela
Published: November 2010

Ionizing radiations from a 60‐Co source have been employed for inducing radical reactions finally leading to the grafting of unsaturated olygomers and vinyl monomers onto the surface and micropores of precipitated silica Zeosil 1165 (150–170 m2/g). The target was to obtain modified silica with enhanced polar compatibility with respect to polybutadiene and styrene‐butadiene copolymers rubber matrices and suited to favour the formation of chemically bound rubber in a vulcanization process. The latter property was expected to follow from the characteristics of free radical reactivity arising from the unsaturations present in the organic coating. Three classes of modified silica have been prepared: A)silica coated with polybutadiene olygomers with Mn in the range 1000–5000 and having a different relative content of 1,4‐cis, 1,4‐trans and vinyl double bonds 1,2; B)Silica coated with polybutadiene olygomers further modified by subsequent grafting of styrene monomer. The type A samples were obtained by γ irradiation under vacuum of silica samples pre‐impregnated with the oligomers in the dose range up to 30–200 kGy. Type B samples were obtained via three different steps as outlined in the scheme below:

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The characterization of the modified silica was carried on by elemental and thermogravimetric analysis, FTIR (diffuse reflectance), Raman spectroscopy, inverse gas chromatography (IGC), CP/MAS 29‐Si NMR, granulometry and TEM microscopy.
Poly(lactic acid) Synthesis in Solution Polymerization
Authors: Marques Dina A.S. , Jarmelo Susana , G. Baptista Cristina M.S. , Gil M.H.
Published: November 2010

The step‐growth polymerization of L‐lactic acid in solution was studied in this work. In order to attain a polymer with high molecular weight, the water formed during the polymerization must be continuously removed. The use of organic solvents with high boiling point, drying agents and reduced pressure led to poly(lactic acid) (PLA) with high molecular weight, directly from the monomer. Tin (II) chloride dihydrate, SnCl2.2H2O, was the best of the catalysts tested as it allowed achieving PLA with a molecular weight close to 80 000 g.mol−1. However, the stereoregurarity control is a severe problem in PLA synthesis by step‐growth due to transesterification reactions, which lead to an inversion of the conformation and a decrease of the optical purity of the polymer. Specific rotation measurements were used in this work and showed to be a powerful technique to evaluate the racemization extent. The thermal stability of the PLA samples was evaluated by DSC which exhibits a thermal behaviour similar to the commercial Polylactide.
Living Polymerization of 1‐Trimethylsilyl‐1‐propyne and 4‐Methyl‐2‐pentyne by NbCl5‐Based Catalysts
Authors: Sultanov E. Yu. , Khotimskiy V. S.
Published: November 2010

Sequential homopolymerization of disubstituted acetylenes 1‐trimethylsilyl‐1‐propyne and 4‐methyl‐2‐pentyne by NbCl5–Ph3SiH was investigated and the main evidence of living polymerization, namely, continuation of chain propagation after addition of a new portion of monomer was observed. AB and BA type block copolymers of 1‐trimethylsilyl‐1‐propyne and 4‐methyl‐2‐pentyne were synthesized by sequential polymerization of these monomers in presence of NbCl5–based catalytic systems.
Well‐Defined Aminophenolate Zinc and Magnesium Complexes as Excellent Inhitiators for the ROP of Lactides
Authors: Ejfler Jolanta , Szafert Sławomir , Sobota Piotr
Published: November 2010

A series of molecular homo and heteroleptic zinc and magnesium compounds with aminophenolate ligands [(µ,η2‐L2)ZnEt]2 (1), [(η2‐L2)Zn(µ‐BnO)]2 (2), [Zn(η2‐L2)2] (3), [Zn(η2‐L3)2] (4), [Mg(η2‐L3)2] (5) (L2‐H = N‐[methylene(2‐hydroxy‐3,5‐di‐tert‐butylphenyl)]‐N‐methyl‐N‐cyclohexylamine, L3‐H = N‐[methylene(2‐hydroxy‐3,5‐di‐tert‐butylphenyl)]‐N‐methyl‐N‐methyl‐1,3‐dioxolaneamine) have been prepared and characterized. The homoleptic complexes 3–5 are most probably a mixture of diastereoisomers that in solution show an interesting dynamics which plays an important role in their catalytic behavior. The complexes 2–5 are efficient initiators in ring‐opening polymerization (ROP) of lactides to produce polymers with desired molecular weight and narrow polydispersity.
Photopolymerizable Elastomers for Vascular Tissue Regeneration
Authors: Baudis Stefan , Steyrer Bernhard , Pulka Thomas , Wilhelm Harald , Weigel Guenter , Bergmeister Helga , Stampfl Juergen , Liska Robert
Published: November 2010

The aim of this study was to design new resin formulations for blood vessel substitutes with small inner diameter that can be 3D‐printed by Additive Manufacturing (AM). Commercially available urethane oligomer acrylates as crosslinking agents (CAs) with different reactive diluents (RDs) and/or thiol chain transfer agents (CTAs) were examined. It could be shown that the properties of photopolymers of carefully selected CA/RD/CTA combinations can be varied in a wide range, also to fit with those of natural blood vessels. Moreover, these materials showed good biocompatibility in in‐vitro cell culture tests with endothelial cells. A new method to assess the tear resistance of the new materials in comparison with natural blood vessels was designed and established. The tear resistance of the developed photopolymers already approaches those of natural material, although there is still need of improvement. The 3D‐structuring of optimized resin system succeeded. Hence AM has proven to be an ideal tool to manufacture parts with the complex structure of natural blood vessels.
Prediction of Rheological and Chemical Properties of Different Starches Used in the Paper Industry by Near Infrared Spectroscopy (NIRS)
Authors: Schrampf Eva , Leitner Erich
Published: November 2010

Starch is one of the most abundant biopolymers, consisting of the polysaccharides amylose and amylopectin and other minor but characteristic constituents depending on the origin. Potatoes, maize, wheat, rice and tapioca are the sources of commercial interest with a large variety of applications both in food and non food areas. The measurements of over hundred starch samples were accomplished over a range of 4000–10000 cm−1 in diffuse reflectance and transmission mode. Quantitative prediction models, based on a partial least squares (PLS) algorithm for the determination of fat content, the main fatty acids, water content, tendency to retrogradation and viscosity were developed. All models are characterized by high correlation coefficients (R2 > 0,98). Principal components analysis (PCA) was applied successfully to distinguish starches regarding their source, provenience and their degree of modification. Both quantitative and qualitative models are cross validated.
Thermoresponsive Hydrogels from Physical Mixtures of Self‐Assembling Peptide and its Conjugate with PNIPAAm
Authors: Maslovskis A. , Saiani A. , Miller A.F.
Published: November 2010

The phase behavior and rheology of a range of physical mixtures of self‐assembling octapeptide FEFEFKFK and its conjugate with the thermoresponsive polymer poly(N‐isopropylacrylamide) (PNIPAAM) have been studied. These systems typically combined the thermo‐responsive character of PNIPAAM and the gelling property of octapeptides where both the elastic behavior and macroscopic melting of the system could be controlled by varying the ratio of pure peptide to peptide‐polymer conjugate.
New Route to Polymeric Nanoparticles by Click Chemistry Using Bifunctional Cross‐Linkers
Authors: de Luzuriaga Alaitz Ruiz , Perez‐Baena Irma , Montes Sarah , Loinaz Iraida , Odriozola Ibon , García Ignacio , Pomposo José A.
Published: November 2010

A new route to functional polymeric nanoparticles (PNPs) of different chemical nature in the 3 to 20 nm size range is reported by combining both radical addition fragmentation chain transfer (RAFT) polymerization and “click” chemistry (CC) techniques. RAFT polymerization was employed for the synthesis of well‐defined statistical copolymers with pending –Cl groups along the macromolecular chain. After transformation of the –Cl groups to –N3 groups by treatment with sodium azide, an appropriate bifunctional cross‐linker is employed to obtain PNPs under CC conditions promoting intramolecular cycloaddition (cross‐linking). Following this new route, polystyrene, poly(alkyl (meth)acrylate), polymethacrylic acid, poly(sodium styrenesulfonate) and poly(N‐isopropyl) NPs have been synthesized and in‐deep characterized.
Control of Nano‐Scale Structuring and Reinforcement in Rotational Molding of Polyethylene
Authors: Kulikov Oleg , Hornung Klaus , Wagner Manfred
Published: November 2010

Polyethylene (PE) resins used for Rotational Molding have usually particle sizes less than 0.8 mm and used as powders or micro‐pellets. During heating in a rotating mould, these particles get fused and merge into one piece. A disadvantage of the rotomolding process is long cycle times that affect the production rate and increase thermal degradation of the polymer. One of the problems in rotomolding is bubbles of gasses trapped during sintering of the PE powders which reduce mechanical strength of the article produced. We propose to use reacting mixtures of PEG with citric acid as Processing Additive (PA) to rotomolding grades of PE. Silica fume and vinyl‐silanes can be other ingredients of the additive package. The PA accelerates sintering of the PE particulates and greatly reduces number of bubbles in the melt but at high concentrations it impedes flow of the particles. Powders are characterized by low flowability while micro‐pellets have too high flowability for rotomolding. To improve the rotomolding process we propose to fabricate micro‐pellets by extrusion of PE resins comprising the PA at reduced temperatures and pelletizing in open air. The same PA reduces extrusion pressure and suppresses flow instabilities during pelletizing as well as adjusts flowability of micro‐pellets to optimum, accelerates sintering of the PE particulates and removes bubbles from the PE melt. Mechanisms of the observed improvements are discussed.
About Durability of Biodegradable Polymers: Structure/Degradability Relationships
Authors: Commereuc S. , Askanian H. , Verney V. , Celli A. , Marchese P.
Published: November 2010

Up to now materials were chosen to satisfy specific property(ies) in relation with the required application. Nowadays, a specific attention has to be devoted to the durability of this property regarding to the lifetime duration. It is the reason why, we paid attention about degradability. Thus, a screening of bio‐ and photodegradability of various selected (co)polyesters has been achieved in order to get better insights about structure / durability relationships. We developed tools allowing the prediction of the behavior of materials upon ageing and the evolution of their properties, regarding to their initial chemical structures. Hence, we could be able to design (co)polyesters characterized by well‐adapted physical, thermal and mechanical properties, but also, with high photostability and/or high biodegradability.
Water‐Soluble Polyelectrolytes with Ability to Remove Arsenic
Authors: Rivas Bernabé L. , Sánchez Julio , Pooley S. Amalia , Basaez Luis , Pereira Eduardo , Bucher Christophe , Royal Guy , Aman Eric Saint , Moutet Jean‐Claude
Published: November 2010

Arsenic species can be removed from aqueous solutions using the liquid‐phase polymer‐based retention, LPR, technique. The LPR technique removes ionic species by functional groups of water‐soluble polyelectrolytes (WSP) and then using a ultrafiltration membrane that does not let them pass through the membrane, thus separating them from the solution. The ability of WSP with groups (R)4N+X− to remove arsenate ions using LPR was studied. The interaction and arsenate anion retention capacity depended on: pH, the quaternary ammonium group's counter ion, and the ratio polymer: As(V), using different concentrations of As(V). Water‐soluble polychelates were also used for one‐step retention of As(III) in solution. The complex of poly(acrylic acid)‐Sn, 10 and 20 wt‐% of metal gave a high retention of As(III) species at pH 8, although the molar ratio polychelate: As(III) was 400:1. The enrichment method was used to determine the maximum retention capacity (C) for arsenate anions in aqueous solutions at pH 8. In similar conditions, the values of C were 142 mg g−1 for P(ClAETA) and 75 mg g−1 for P(SAETA). The combined treatment of arsenic aqueous solutions by electrocatalytic oxidation (EO) to convert the species of As(III) to As(V) with the LPR technique quantitatively removed arsenic.
Preparation, Characterization and Controlled Release Investigation of Biocompatible pH‐Sensitive PVA/PAA Hydrogels
Authors: Manavi‐Tehrani Iman , Rabiee Mohammad , Parviz Maryam , Tahriri Mohammad Reza , Fahimi Zahra
Published: November 2010

In the present research hydrogel films based on polyvinyl alcohol (PVA) and polyacrylic acid (PAA) blend, with various crosslink densities, have been prepared through different thermal treatment. The results of FTIR and DSC confirmed quality and quantity of conclusion on miscibility of PVA/PAA blends, respectively. Besides, biocompatibility of the samples has been proved in cytotoxicity tests using L929 cells, according to ISO10993–5. Water uptake of the hydrogel blends is measured. pH sensitivity properties of blends are studied with and without boiling in NaOH solutions where the effect of swelling in water before boiling has also been investigated. Preswellings in water and NaOH concentration have been found to be mainly effective on pH sensitivity of PVA/PAA blends. Biocompatibility and pH sensitivity behavior make these hydrogels appropriate candidates to orally deliver drugs such as insulin and peptides that can be released in basic pH of intestine. The stability of these films in acidic solutions and its expansion and also the consequent release of drugs in basic solutions have been studied by using Teofilin as a model drug by UV‐spectrophotometeric measurements.
SAXS Studies of Heating/Cooling Cycle Behavior of Biodegradable BTA/PLA‐b Blends
Authors: Kwiatkowski Ryszard , Dacko Piotr
Published: November 2010

Summary: The blends of BTA copolyester (i.e. the Ecoflex® copolyester) and PLA‐b amorphous polylactide with following weight ratios: 90/10, 70/30 and 50/50 have been prepared and their phase structure have determined by using X‐ray methods and DSC method. The thermal behavior of the blends was tested by time resolved SAXS measurements performed during heating/cooling thermal cycle treatment (20÷135÷20 °C). As a result of analysis of desmeared Lorentz corrected SAXS curves using the Hosemann scattering function the changes of characteristics of lamellar structure of BT‐BA stacks within the blends have been determined and linked with changes of lamellar superstructure of the BTA reference sample. Among other thinks, it was found that the rate of the heating induced growth of the BA amorphous layers thickness and consequently of long period of BT‐BA stacks structure increases with the increase of PLA‐b amount, and that BT‐BA stacks are formed significantly later (ca. 5 min.) during the cooling of the melted blends than during the cooling of the melted BTA copolyester.
Well‐Defined Oxide Core‐Poly(vinyl pyrrolidone) Shell Nanoparticles: Interactions and Multi‐Modal Glass Transition Dynamics at Interfaces
Authors: Bershtein Vladimir , Gun'ko Vladimir , Egorova Larisa , Guzenko Natalia , Pakhlov Eugene , Ryzhov Valery , Zarko Vladimir
Published: November 2010

Interfacial interactions and dynamics were studied in silica and alumina core‐poly(vinyl pyrrolidone) (PVP) shell nanoparticles with different shell thicknesses starting from 1‐2 nm (monolayer); their geometry and structural organization were comprehensively characterized by several techniques. Far‐ and mid‐IR spectroscopy, combined with DSC activation analysis of the glass transition, allowed to register hydrogen bonding and Lewis/Brønsted interactions, and the multi‐modal glass transition dynamics in PVP nanoshells, as well as their interrelationship. For PVP monolayer, only a few “abnormal” modes constituted glass transition which covered the temperature range from 80 to 230 °C, with varying the activation energy by an order of magnitude.
Modification of Silica by Liquid Polybutadienes Containing Alkoxysilane Groups
Authors: Colucci Giovanna , Di Gianni Anna , Bongiovanni Roberta , Priola Aldo , Torello Francesca , Bracco Silvia , Sozzani Piero
Published: November 2010

Summary: The present work describes a method to modify the surface of silica, reducing its polar character and making it compatible and dispersible into hydrocarbon based elastomers. A liquid low molar mass polybutadiene (PB) was grafted with mercaptopropyltrimethoxysilane (MPTS) via radical addition of the thiol group to the double bonds. The silanized PB was reacted with silica via thermal condensation with its silanol groups. 29Si NMR spectra showed that the condensation reaction of the trifunctional silane involved one or two alkoxy groups, while the third alkoxy group remained unreacted, probably for steric reasons. The characterization of the functionalized silica particles was performed by contact angle measurements and TGA analysis.
Experimental Studies for Modelling the Phase Behaviour of Monomer/Polymer/Disc Composites
Authors: Torrens Francisco , Castellano Gloria
Published: November 2010

Nanoparticles do not stabilize the mixtures of epoxy monomer (prepolymer)/thermoplastic modifier (PS) and the ones of thermoplastic modifier dispersed within cured epoxy matrix. A small amount of thermoplastic co‐polymer poly(styrene‐b‐methyl methacrylate) [P(S‐b‐MMA)] of MMA 4–22 wt.%, mixed with PS, makes compatible the mixtures with monomer epoxy precursor and cured epoxy matrix. The mixtures of cured epoxy matrix with thermoplastic consisting of PS and P(S‐b‐MMA), with nanofil 1%, are stable: the instability produced by the nanofil is overcome by the stability provided by the co‐polymer. A model by Balazs' group to explain the phase behaviour of polymer/clay composites is extended.
Reactive EB Processing of Polymer Compounds
Authors: Gohs Uwe , Leuteritz Andreas , Naskar Kinsuk , Volke Sebastian , Wiessner Sven , Heinrich Gert
Published: November 2010

Polymer modification with high energy electrons is well‐established in polymer industry and used for degradation, cross‐linking, grafting, curing, and polymerization. These applications use local and temporal precise input of energy in order to generate excited atoms or molecules as well as ions for subsequent molecule changes via radical induced chemical reactions. Reactive electron beam (EB) processing combines melt mixing process and chemical reaction simultaneously. For this purpose, a 1.5 MeV electron accelerator was directly coupled to an internal mixer in order to induce chemical reactions by energy input via high energy electrons under dynamic conditions of melt mixing of different polymer compounds. In the present study, reactive EB processing was used for the development of a flame retardant polyethylene composite as well as Thermoplastic Vulcanizate. The influence of absorbed dose as well as electron energy and electron treatment time was studied. Increased values of both tensile strength and elongation at break of polymer compounds indicated in‐situ compatibilization upon reactive EB processing.
Prediction of Tensile Curves of Rubber Materials by Different Network Models
Authors: Zidek Jan , Nezbedova Eva , Jancar Josef
Published: November 2010

The paper presents application of rubber elasticity theory to the predictive model of tensile mechanical properties. Poly(methyl methacrylate) was chosen as a model polymer. The input dates were crosslink density and type of chain. The crosslink density was taken from swelling experiment. Two types of chain were analyzed, namely worm like and chain with the realistic function of dihedral potential. Dihedral potential function was derived from molecular model of chain segment. Predictive tensile curve was compared with experimental one. The similarity of potential functions of selective polymers (polypropylene, poly‐vinylchloride, poly‐vinylalcohol, poly‐vinylfluoride, polystyrene) enables to generalize this procedure.
A 1H NMR and theoretical investigation of the conformations of some monosubstituted cyclobutanes
Authors: Abraham Raymond J. , Leonard Paul , Tormena Cláudio F.
Published: November 2010

The complete analysis of the complex 1H NMR spectra of some monosubstituted cyclobutanes was achieved to give all the 1H chemical shifts and nJHH (n = 2, 3 and 4) coupling constants in these molecules. The substituent chemical shifts of the substituents in the cyclobutane ring differ significantly from those in acyclic systems. For example, the OH and the NH2 groups in cyclobutanol and cyclobutylamine produce a large shielding of the hydrogens of the opposite CH2 group of the ring compared with little effect on the comparable methylene protons of butane. These effects and the other 1H shifts in the cyclobutanes were modelled successfully in the CHARGE program. The RMS error (calculated vs observed shifts) for the 34 1H shifts recorded was 0.053 ppm. The conformational equilibrium in these compounds between the axial and the equatorial conformers was obtained by comparing the observed and the calculated 4JHH couplings. These couplings in cyclobutanes, in contrast to the corresponding 3JHH couplings, show a pronounced orientation dependence; 4Jeq–eq is ca 5 Hz and 4Jax–ax ca 0 Hz. The couplings in the individual conformers were calculated at the B3LYP/EPR‐III level. The conformer energy differences ΔGax–eq vary from 1.1 kcal mol−1 for OH to 0.2 kcal mol−1 for the CH2OH substituent. The values of the conformer energy differences are compared with the previous IR data and the corresponding theoretical values from molecular mechanics (MM) and DFT theory. Generally, good agreement is observed although both the MM and the DFT calculations deviate significantly from the observed values for some substituents. Copyright © 2010 John Wiley & Sons, Ltd.
Development and psychometric testing of the register – connectedness scale for older adults
Authors: Register M. Elizabeth , Herman JoAnne , Tavakoli Abbas S.
Published: November 2010

Connectedness, maintaining active engagement with life, is crucial to successful aging. Yet, no instruments were found to measure connectedness. The purpose of this study was to develop and test a connectedness scale for older adults. A 72‐item instrument was administered to 428 community‐dwelling older adults. The sample was largely female, White widows/widowers, with a mean age of 76 (SD 6.95) years. The instrument was reduced to 45 items representing five factors with loadings ranging from .40 to .86. The factor labels and their reliability estimates were: (a) self‐regulating (.86), (b) facing aging (.85), (c) being part of a family (.87), (d) having friends (.87), and (e) being spiritual (.88). This promising instrument may advance the science of successful aging. © 2010 Wiley Periodicals, Inc. Res Nurs Health 34:60–72, 2011
Thermal stresses and birefringence in quenched tubes and rods: Simulation and experiment
Authors: Carrillo Antonio J. , Isayev A.I.
Published: November 2010

Measurements and simulations of the radial distribution of the thermal birefringence components, Δn and nθθ − nrr, and the average birefringence, , in free quenched tubes and rods of polystyrene (PS) and polycarbonate (PC) at different initial temperatures were carried out. The thermal stress and birefringence components were simulated using the linear viscoelastic and photoviscoelastic constitutive equations combined with the first‐order rate equation for volume relaxation and the master curves for the Young's relaxation modulus and strain‐optical coefficient functions of polymers. The numerical procedures used to discretize the governing equations using finite difference method were described. The obtained numerical results provided the evolution of stress and birefringence components with time during and after quenching and an explanation of the measured residual birefringence distribution in quenched tubes and rods. It was also found that the thickness of the slices removed from the samples to measure the thermal birefringence components, Δn and nθθ − nrr, was critical, in particular, when the initial temperatures were close to the glass transition temperature of polymers. With an increase of the initial temperature during quenching, a better agreement between the simulated and measured birefringence components was obtained. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers
Preparation and properties of PBS/sisal‐fiber composites
Authors: Feng Yanhong , Shen Hanzhi , Qu Jinping , Liu Bin , He Hezhi , Han Liyan
Published: November 2010

We report the preparation of polybutylene succinate (PBS)/sisal‐fiber (SF) composites. The effects of mixing temperature and of steam‐explosion pretreatment of SFs on the mechanical properties of the composites were investigated, and the mechanism of action was studied by infrared spectroscopy, scanning electron microscopy, and x‐ray photoelectron spectroscopy. The results indicate that as the mixing temperature increases, PBS flows better and can graft onto steam‐exploded sisal fiber (SESF), the interfacial bond property between SESF and PBS improves, and the mechanical properties of the composites improve. The mechanical properties of the composites are maximal for a mixing temperature of 200°C. The results also demonstrate that the cellulose content and the specific fiber surface area can be increased by steam‐explosion pretreatment, so that the mechanical properties of the composites can be improved. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers
Automated batch emulsion copolymerization of styrene and butyl acrylate
Authors: Mballa Mballa Monique A. , Schubert Ulrich S. , Heuts Johan P. A. , van Herk Alex M.
Published: November 2010

This article describes a method for carrying out emulsion copolymerization using an automated synthesizer. For this purpose, batch emulsion copolymerizations of styrene and butyl acrylate were investigated. The optimization of the polymerization system required tuning the liquid transfer method, sufficient oxygen removal from the reaction medium and setting a proper sampling procedure. The monomer conversion‐time plots obtained with gas chromatography revealed a good reproducibility of the automated reaction kinetics. Furthermore, the particle size distributions and the properties of the final products were found to be highly reproducible. The performance of the automated reactions was subsequently compared with the conventional ones: similar reproducibility of either synthetic method was observed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Syndiospecific polymerization of styrene in the presence of cyclic olefins: A new approach for molecular weight, molecular weight distribution, and stereoregularity controls for syndiotactic polystyrene
Authors: Tzeng Fu‐Yuan , Tsai Jing‐Cherng
Published: November 2010

A new approach for facilitating microstructural controls for syndiotactic polystyrene (sPS), in which, styrene polymerization is conducted in the presence of cyclic olefins and hydrogen, is proposed. Detailed structural analyses revealed that cyclic olefins are not incorporated into the polystyrene main chain; instead, they are capable of interrupting the chain propagation processes by binding onto the active catalyst to form a cyclic‐olefin‐coordinated active site. Thus, in the presence of hydrogen, chain transfer by hydrogen addition occurs selectively, which leads to the generation of drastically lower molecular weight sPS with a narrower range of molecular weight distribution. Chain end structural analyses of the resulting polymers revealed that styrene polymerization under theses conditions involves a selective chain transfer pathway for providing styrene polymers with uniform chain end structures. A unique method for inducing a selective chain transfer reaction by using non‐incorporated cyclic olefins to regulate the chain reaction mechanism is demonstrated. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Syntheses and characterization of block copolymers of poly(aliphatic ester) with clickable polyphosphoester
Authors: Wang Yu‐Cai , Yuan You‐Yong , Wang Feng , Wang Jun
Published: November 2010

We report a series of biocompatible and biodegradable block copolymers of poly(ε‐caprolactone) with “clickable” polyphosphoester (PPE). The block copolymers are synthesized through controlled ring‐opening polymerization of five‐membered cyclic phosphoester monomer, propargyl ethylene phosphate (PAEP), initiated with poly(ε‐caprolactone) macroinitiator. The polymerization followed first‐order kinetics with living polymerization characteristics, thus the molecular weight and composition of copolymers are tunable by adjusting the feed ratio of PAEP monomer to macroinitiator. Azide‐functionalized poly(ethylene glycol) has been grafted to the copolymer to demonstrate the reactive feasibility by Cu(I)‐catalyzed “click” chemistry of azides and alkynes, generating “brush‐coil” polymers. The mild conditions associated with the click reaction are shown to be compatible with poly(ε‐caprolactone) and PPE backbones, rendering the click reaction a generally useful method for grafting numerous types of functionality onto the block copolymers. The block copolymers also show good biocompatibility to cells, suggesting their suitability for a range of biomaterial applications. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Synthesis, characterization and properties of N‐maleimide side‐chain liquid crystalline copolymers
Authors: de Ojeda J. M. Bautista , Quijada‐Garrido I. , Barrales‐Rienda J. M.
Published: November 2010

A homologous series of side‐chain liquid crystalline (SCLC) poly{[N‐[10‐((4‐(((4′‐n‐hexyloxy)benzoyl)oxy)phenoxy)carbonyl)‐n‐decyl]maleimide]‐co‐[N‐(n‐octadecyl)maleimide]} [(ME6)‐co‐(MI‐18)] random copolymers with various MI‐18 contents have been synthesized and their properties studied. The high content in threo‐disyndiotactic sequences of the maleimide main chain seems responsible for the stability of the highly ordered smectic mesophase. The relationship between structure and composition on thermotropic mesophase was investigated by polarizing optical microscopy, differential scanning calorimetry, and X‐ray diffraction. For copolymers with mesogenic unit contents less than ∼0.655 molar fraction the transition from (SA) texture to isotropic (I) is maintained, as shown by the TCl, ΔHCl and ΔSCl amounts and intermolecular spacing 4.42–4.53 Å and intralayer correlation lengths of 44.2–45.2 Å. The layer thickness does not appreciably depend on copolymer composition. However, copolymers with non‐mesogenic comonomer MI‐18 molar contents larger than >0.655 molar fraction X(M), are no longer liquid crystalline materials, despite its packing is preserved without any detectable appearance of birefringence. Thermodynamic boundaries of the liquid crystalline state have been established through a phase diagram. The properties of this n‐hexyloxy pendant group‐based series are compared to those of the analogous materials containing methoxy pendant groups (ME1), and differences are accounted for in terms of the local side‐chain packing within the mesophase. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Adhesion of nonplanar wrinkled surfaces
Authors: Kundu Santanu , Davis Chelsea S. , Long Thomas , Sharma Ravi , Crosby Alfred J.
Published: November 2010

Topological patterns on polymer surfaces can significantly alter and control adhesion. In this study, the effect of surface wrinkles on a spherical surface on adhesion has been studied. Surface wrinkling induced by swelling of a crosslinked polydimethylsiloxane elastomer constrained by a stiff, thin surface layer (silicate) is used to produce topographic features of various length scales over a large curved area. By controlling the properties of the stiff layer and the applied strain conditions, surface wrinkles of varying amplitude and wavelength are obtained. The effect of wrinkle morphology on adhesion is quantified, and the results display a transition from enhancement of adhesion to decrease depending upon wrinkle dimensions. A simple phenomenological model is proposed that describes the change of adhesion behavior as a function of wrinkle morphology. Our results provide a critical understanding toward tuning the adhesion behavior of nonplanar surfaces consisting of periodic topographic structures. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011