bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative study of endoscopic thyroidectomy versus conventional open thyroidectomy in papillary thyroid microcarcinoma (PTMC) patients
Authors: Jeong Jong Ju , Kang Sang‐Wook , Yun Ji‐Sup , Sung Tae Yon , Lee Seung Chul , Lee Yong Sang , Nam Kee‐Hyun , Chang Hang Seok , Chung Woong Youn , Park Cheong Soo
Published: August 2009

Background

The aim of this study was to evaluate and compare the early surgical outcomes of endoscopic and conventional open thyroidectomies in patients with papillary thyroid microcarcinoma (PTMC).

Methods

Between September 2005 and December 2007, 499 patients with PTMC were enrolled. 275 patients underwent gasless endoscopic thyroidectomy via the axillary route (endo group), and 224 patients underwent conventional open thyroidectomy (open group). We analyzed the patient's clinico‐pathologic characteristics and surgical completeness between the two groups.

Results

The endo group was younger than the open group. The open group underwent more extensive surgery than the endo group. The operative time was longer in the endo group than the open group (138.5 ± 49.0 min vs. 105.5 ± 41.6 min; P < 0.0001), and a lesser number of lymph nodes were retrieved in the endo group compared to the open group (5.05 ± 2.94 vs. 5.96 ± 4.50, P = 0.007). We experienced complications in the endo group, such as transient hypocalcemia, transient RLN palsies, tracheal injuries, and esophageal injuries. There was no abnormal uptake on RAI scans in the two groups. From among patients who had undergone total thyroidectomy, all patients in the endo group had <1 ng/ml of serum Tg post‐operatively; the seven patients in the open group had >1 ng/ml of serum Tg post‐operatively. Tumor recurrence was detected in the open group only (n = 6). Also we checked the post‐operative Tg in patients who had undergone lobectomy in the two groups, and found that there were no statistical differences in the two groups.

Conclusions

According to our experience, gasless endoscopic thyroidectomy using a trans‐axillary approach is a safe and feasible alternative to conventional open thyroidectomy in selected patients with PTMC. J. Surg. Oncol. 2009;100:477–480. © 2009 Wiley‐Liss, Inc.
The effect of study design and analysis methods on recovery rates in Bell's palsy
Authors: Berg Thomas , Marsk Elin , Engström Mats , Hultcrantz Malou , Hadziosmanovic Nermin , Jonsson Lars
Published: August 2009

Objectives/Hypothesis:

We investigated how study design affects the rate of recovery in Bell's palsy.

Study Design:

Prospective, randomized, double‐blind, placebo‐controlled, multicenter trial.

Methods:

Data were extracted from the Scandinavian Bell's palsy study, which included 829 patients. The study design was factorial; 416 patients given prednisolone, 413 not given prednisolone, 413 patients given valacyclovir, 416 not given valacyclovir. Data were analyzed with intention‐to‐treat principle and complete‐case analysis methods and recovery was defined as Sunnybrook score 100, House‐Brackmann grade I or ≤grade II at 12 months.

Results:

With the intention‐to‐treat principle and last‐observation‐carried‐forward method (n = 829) and recovery defined as Sunnybrook 100, 300 of the 416 patients (72%) receiving prednisolone had recovered compared with 237 of the 413 (57%) who did not receive prednisolone (P < .0001). With recovery defined as House‐Brackmann grade I, the corresponding recovery rates were 324 of 416 (78%) and 266 of 413 (64%) (P < .0001). With complete‐case analysis and recovery defined House‐Brackmann grade I (n = 782), 335 of 389 patients (86%) given prednisolone recovered compared with 277 of 393 (70%) in the group not given prednisolone (P < .0001). With recovery defined as House‐Brackmann ≤grade II (n = 797), the corresponding recovery rates were 380 of 396 (96%) and 353 of 401 (88%) (P < .0001). The analysis method affected the recovery rates in the valacyclovir and no‐valacyclovir groups in a similar way as in the prednisolone and no‐prednisolone groups.

Conclusions:

Recovery rates in a Bell's palsy study are substantially affected by the choice of analysis method and definition of recovery. Laryngoscope, 2009
High temperature oxidation of FeCrAl‐alloys – influence of Al‐concentration on oxide layer characteristics
Authors: Engkvist J. , Bexell U. , Grehk M. , Olsson M.
Published: August 2009

The superior high temperature oxidation resistance of FeCrAl alloys relies on the formation of a dense and continuous protective aluminium oxide layer on the alloy surface when exposed to high temperatures. Consequently, the aluminium content, i.e. the aluminium concentration at the alloy–oxide layer interface, must exceed a critical level in order to form a protective alumina layer. In the present study the oxidation behaviour of six different FeCrAl alloys with Al concentrations in the range of 1.2–5.0 wt% have been characterised after oxidation at 900 °C for 72 h with respect to oxide layer surface morphology, thickness and composition using scanning electron microscopy, energy dispersive X‐ray spectroscopy and Auger electron spectroscopy. The results show that a minimum of 3.2 wt% Al in the FeCrAl alloy is necessary for the formation of a continuous alumina layer. For Al concentrations in the range of 2.0–3.0 wt% a three‐layered oxide layer is formed, i.e. an oxide layer consisting of an inner alumina‐based layer, an intermediate chromia‐based layer and an outer iron oxide‐based layer. In contrast, the 1.2 wt% Al FeCrAl alloy is not able to form a protective oxide layer inhibiting extensive oxidation.
A stochastic analysis of the effect of magnetic field on the pitting corrosion susceptibility of pure magnesium
Authors: Li J. , Zhang T. , Shao Y. , Meng G. , Wang F.
Published: August 2009

The effect of magnetic field on the pitting corrosion susceptibility of pure magnesium was investigated by stochastic approaches. Stochastic models had been applied to simulate pitting corrosion as the combination of two physical processes: pit initiation and pit growth. The results revealed that magnetic field increased the pitting corrosion susceptibility of pure magnesium. For the pit initiation process, the presence of magnetic field changed the mechanism of pit initiation from the parallel birth and death stochastic model (B1) to the parallel birth stochastic model (A3). Magnetic field increased the pit generation rate λ while decreased the repassivation rate µ, which indicated that magnetic field accelerated the pit initiation process of pure magnesium. For the pit growth process, magnetic field didn't change the pit growth mechanism, but it could decrease the ability of repassivation of pitting corrosion resulting in a great probability for the stable pitting corrosion to grow up with a higher growth rate and finally develop into larger pit cavity.
Effect of ultrasound treatment of AlSi5 liquid alloy on corrosion resistance
Authors: Arrighini A. , Gelfi M. , Pola A. , Roberti R.
Published: August 2009

The application of power ultrasound to liquid alloys can be a simple and cost effective method to induce both degassing and grain refinement in a single step, without the need of inert gas or inoculants additions. In this paper, the treatment of liquid hypoeutectic AlSi5 alloy by ultrasound waves and its effects on microstructure were investigated. The corrosion behavior of ultrasound treated samples was compared to that of the non‐treated ones by means of immersion and electrochemical tests. It was observed that the ultrasound treated alloy offers better quality, higher mechanical properties and improved corrosion resistance, as a consequence of a more uniform distribution of the solute.
Effect of corrosion on bond strength of steel and non‐metallic reinforcement
Authors: Demis S. , Pilakoutas K. , Apostolopoulos Ch. Alk.
Published: August 2009

Research attempts on the effect of environmental corrosion on bond between steel bars and concrete, report considerable losses of bond strength. Alternative solutions to the corrosion problem include the use of non‐metallic reinforcement. In this paper the effects of environmental corrosion (through accelerated carbonation) on the bond properties of fiber reinforced polymer (FRP) bars with the surrounding concrete are investigated. The work presented is part of an extensive project addressing the durability of FRP in concrete 1. It was found out that, in contrast to what is generally believed, concrete alkalinity does not have a major impact on the durability of FRP bar and its bond strength. The expected bond deterioration due to carbonation is more than compensated by the increase in compressive strength due to time and carbonation, contrary to the case when steel reinforcement is used.
Energy storage ability and anti‐corrosion protection properties of TiO2–SnO2 system
Authors: Zhou M.‐J. , Zeng Z.‐O. , Zhong L.
Published: August 2009

TiO2/SnO2 and TiO2–SnO2 coatings were prepared on type 304 stainless steel by sol–gel method, respectively. TiO2/SnO2 coating is compared with TiO2–SnO2 coating in terms of energy storage ability and anti‐corrosion property. The two coatings can be charged with reductive energy under UV irradiation in 3 wt% aqueous NaCl. The self‐discharging time of the TiO2/SnO2 coating is slower than that of the TiO2–SnO2 coating. The slow discharging may be suitable for an anti‐corrosion application for metal. In the case where TiO2/SnO2 coating electrode is electrochemically charged at −0.38 V (vs. SCE) for 1 h, it can maintain a good cathodic protection for type 304 stainless steel for 7 h in the dark, while the TiO2–SnO2 coating electrode can only maintain a good cathode protection for 0.5 h in the dark.
Corrosion behaviour of Mg–Al alloys with Al–11Si thermal spray coatings
Authors: Pardo A. , Merino M. C. , Casajús P. , Mohedano M. , Arrabal R. , Matykina E.
Published: August 2009

The corrosion resistance of AZ31, AZ80 and AZ91D Mg–Al alloys with Al–11Si thermal spray coatings was evaluated by electrochemical and gravimetric measurements in 3.5 wt% NaCl solution. The changes in the morphology and corrosion behaviour of the Al–11Si coatings induced by a cold‐pressing post‐treatment under 32 MPa were also examined. The as‐sprayed Al–11Si coatings revealed high degree of porosity and poor corrosion protection, which resulted in galvanic acceleration of the corrosion of the magnesium substrates. The application of a cold‐pressing post‐treatment produced more compact Al–11Si coatings with better bonding at the substrate/coating interface and slightly higher corrosion resistance. However, interconnected pores remained in the cold‐pressed coatings due to the low plasticity of the Al–11Si powder and galvanic corrosion of the substrate was observed after immersion in 3.5 wt% NaCl for 10 days.
Study of microstructure and corrosion kinetic of steel guitar strings in artificial sweat solution
Authors: Rezić I. , Ćurković L. , Ujević M.
Published: August 2009

Corrosion processes of strings on musical instruments occur frequently. Such processes significantly influence sound quality, but also human health because metals may provoke skin allergy. Therefore, in this study the corrosion process of six guitar strings and metal ions release associated with nickel allergy was monitored after immersion in sweat solution for 28 days. Dissolution of metal ions was measured as a function of time, and the changes of the samples after 28 days were studied by SEM/EDS. The results have shown that the amounts of dissolved metal ions in corrosive solution are decreasing in the following order: Fe3+ < Sn2+ < Mn2+ < Si4+ < Ni2+. The corrosion of electric guitar strings in artificial sweat solution was determined by the solubility of samples. The electric guitar strings E6, A5 and D4 corrosion kinetic in artificial sweat followed parabolic rate relation, while g3, h2 and e1 strings followed linear rate relation. After the 4 weeks of monitoring, the quantities of the nickel eluted ions did not exceed the limits prescribed by standard regulations. Therefore, such items do not present a threat to human health.
Chitooligosaccharides promote peripheral nerve regeneration in a rabbit common peroneal nerve crush injury model
Authors: Gong Yanpei , Gong Leilei , Gu Xiaosong , Ding Fei
Published: August 2009

Chitooligosaccharides (COSs) are the biodegradation products of chitosan that have been demonstrated with neuroaffinity and/or neuroprotective actions. In this study, we investigated the possible benefits of treatment with COSs on nerve regeneration after crush injuries to peripheral nerves. The rabbits with the crushed common peroneal nerve were treated by daily intravenous injection of 1.5 or 3 mg/kg body weight of COSs or identical volume of saline (as the control) for a 6‐week period. At the end of COSs treatment, electrophysiological assessments, Meyer's trichrome and Masson trichrome staining, and transmission electron microscopy were used to evaluate the regeneration of injured common peroneal nerve and atrophy of the tibialis posterior muscle. The results showed that the compound muscle action potentials, the number of regenerated myelinated nerve fibers, the thickness of regenerated myelin sheaths, and the cross‐sectional area of tibialis posterior muscle fibers were significantly improved in the nerves that received COSs treatment and the results with COSs treatment displayed a dose‐dependent pattern. This study demonstrated that COSs accelerated peripheral nerve regeneration after crush injury to rabbit common peroneal nerves. The COSs could probably become a potential neuroprotective agent for improvement of peripheral nerve regeneration after the injury and deserve for further studies. © 2009 Wiley‐Liss, Inc. Microsurgery, 2009.
Spectral parameter power series for Sturm–Liouville problems
Authors: Kravchenko Vladislav V. , Porter R. Michael
Published: August 2009

We consider a recently discovered representation for the general solution of the Sturm–Liouville equation as a spectral parameter power series (SPPS). The coefficients of the power series are given in terms of a particular solution of the Sturm–Liouville equation with the zero spectral parameter. We show that, among other possible applications, this provides a new and efficient numerical method for solving initial value and boundary value problems. Moreover, due to its convenient form the representation lends itself to numerical solution of spectral Sturm–Liouville problems, effectively by calculation of the roots of a polynomial. We discuss the examples of the numerical implementation of the SPPS method and show it to be equally applicable to a wide class of singular Sturm–Liouville problems as well as to problems with spectral parameter‐dependent boundary conditions. Copyright © 2009 John Wiley & Sons, Ltd.
Oxidative stress and DNA interactions are not involved in Enniatin‐ and Beauvericin‐mediated apoptosis induction
Authors: Dornetshuber Rita , Heffeter Petra , Lemmens‐Gruber Rosa , Elbling Leonilla , Marko Doris , Micksche Michael , Berger Walter
Published: August 2009

The fusariotoxins beauvericin (BEA) and the structurally related enniatins (ENN) are frequent contaminants of grain‐based food and feed. They exert potent cytotoxic activities based on apoptosis induction. Since it is known, that reactive oxygen species (ROS) and DNA damage lead to apoptotic cell death, this study aimed to clarify whether oxidative stress and DNA interactions are involved in ENN‐ and BEA‐induced cytotoxicity. Diverse cellular and molecular assays indicated that oxidative stress does not contribute to ENN‐ and BEA‐induced cytotoxicity. In contrast, both fusariotoxins were shown to exert moderate antioxidative activities. Moreover, only at high concentrations (>100 μM) both mycotoxins were found to intercalate substantially into dsDNA and to inhibit the catalytic activity of topoisomerase I and II. Furthermore, the potent cytotoxic activity of ENN and BEA was shown to be widely independent of cellular mismatch‐ and nucleotide excision repair pathways. Also the ataxia‐telangiectasia mutated (ATM) protein kinase, a well known DNA damage sensor, did not affect BEAs cytotoxic potential while in ENN‐induced cytotoxicity ATM had a detectable but not a major modulating influence. Together, our data suggest that ROS and DNA damage are not key factors in ENN‐ and BEA‐mediated cytotoxicity.
NMR determination of pKa values of indoloquinoline alkaloids
Authors: Grycová Lenka , Dommisse Roger , Pieters Luc , Marek Radek
Published: August 2009

Malaria is one of the most serious global health problems. Isolating new therapeutic agents with potential antimalarial activity from natural sources or preparing such agents either semisynthetically or synthetically is one strategy for solving the problem of resistance constantly evolving to the drugs currently in use.

For alkaloids, the acid–base dissociation constant, pKa, is an important characteristic, thought to be associated with biological activity. In this contribution, pKa values for several indoloquinoline alkaloids were determined by using 1H NMR spectroscopy in a mixture of solvents. The data were recalculated for water solutions using the correction factors reported previously. The structural dependence of the pKa values for cryptolepine and its isomers neocryptolepine, isocryptolepine and isoneocryptolepine as well as some substituted neocryptolepine derivatives is discussed. Copyright © 2009 John Wiley & Sons, Ltd.
Structural characterization of hypoglycin B, a diastereomeric dipeptide from the ackee fruit (Blighia sapida Koenig) by NMR experiments
Authors: Bowen‐Forbes Camille S. , Minott Donna A.
Published: August 2009

The dipeptide hypoglycin B, one of two toxins of the ackee fruit (Blighia sapida Koenig), was characterized for the first time by NMR spectral data, which led to the discovery that it exists naturally as a pair of diastereomers. No distinction was observed in the 1H NMR signals of the diastereomers; however, complete and distinct 13C NMR assignments for the individual diastereomers were made. The 13C NMR spectrum of hypoglycin B compared very well with that of the corresponding signals in the spectrum for hypoglycin A, which is one of its constituent amino acids. The 1H and 13C NMR assignments were further supported by DEPT, gCOSY, gHSQC and gHMBC experiments. Copyright © 2009 John Wiley & Sons, Ltd.
Chebyshev‐like root‐finding methods with accelerated convergence
Authors: Petković M. S. , Rančić L. , Petković L. D. , Ilić S.
Published: August 2009

Iterative methods for the simultaneous determination of simple or multiple complex zeros of a polynomial, based on a cubically convergent Chebyshev method, are considered. Using Newton's and Halley's corrections the convergence of the basic method of the fourth order is increased to five and six, respectively. The improved convergence is achieved with negligible number of additional calculations, which significantly increases the computational efficiency of the accelerated methods. One of the most important problems in solving polynomial equations, the construction of initial conditions that enable both guaranteed and fast convergence, is also studied for the proposed methods. These conditions are computationally verifiable since they depend only on initial approximations, the polynomial coefficients and the polynomial degree, which is of practical importance. Finally, modified methods of Chebyshev's type for finding multiple zeros and single‐step methods based on the Gauss–Seidel approach are constructed. Copyright © 2009 John Wiley & Sons, Ltd.
On the convergence of general stationary iterative methods for range‐Hermitian singular linear systems
Authors: Zhang Naimin , Wei Yi‐Min
Published: August 2009

General stationary iterative methods with a singular matrix M for solving range‐Hermitian singular linear systems are presented, some convergence conditions and the representation of the solution are also given. It can be verified that the general Ortega–Plemmons theorem and Keller theorem for the singular matrix M still hold. Furthermore, the singular matrix M can act as a good preconditioner for solving range‐Hermitian linear systems. Numerical results have demonstrated the effectiveness of the general stationary iterations and the singular preconditioner M. Copyright © 2009 John Wiley & Sons, Ltd.
Combined interior‐point method and semismooth Newton method for frictionless contact problems
Authors: Miyamura Tomoshi , Kanno Yoshihiro , Ohsaki Makoto
Published: August 2009

In the present paper, a solution scheme is proposed for frictionless contact problems of linear elastic bodies, which are discretized using the finite element method with lower order elements. An approach combining the interior‐point method and the semismooth Newton method is proposed. In this method, an initial active set for the semismooth Newton method is obtained from the approximate optimal solution by the interior‐point method. The simplest node‐to‐node contact model is considered in the present paper, that is, pairs of matching nodes exist on the contact surfaces. However, the discussions can be easily extended to a node‐to‐segment or segment‐to‐segment contact model. In order to evaluate the proposed method, a number of illustrative examples of the frictionless contact problem are shown. The proposed combined method is compared with the interior‐point method and the semismooth Newton method. Two numerical examples that are difficult to solve using the semismooth Newton method are solved effectively using the proposed combined method. It is shown that the proposed method converges within far fewer iterations than the semismooth Newton methods or the interior‐point method. Copyright © 2009 John Wiley & Sons, Ltd.
Autonomy or organisation? Reforms in the Ghanaian internal revenue service
Authors: Joshi Anuradha , Ayee Joseph
Published: August 2009

Autonomous Revenue Authorities (ARAs) have recently become a popular organisational reform to improve revenue collection in developing countries. The success of ARAs is commonly attributed to ‘autonomy’ which reduces political interference, and increases financial independence and managerial freedom. This article examines the case of the Ghanaian ARA – the Internal Revenue Service and argues that its strong performance is the result of not ‘autonomy’, but other more nuts and bolts reforms, specifically: (a) strategies designed to direct the focus of the IRS to different taxpayer segments, particularly the informal sector and (b) significant attempts to bring the tax administration closer to the taxpayer through decentralisation and improved taxpayer services. To the extent that autonomy enables ARAs to undertake these other reforms it forms an important piece of the picture, however, they do not require autonomy – they could well be adopted under traditional tax administrations. Copyright © 2009 John Wiley & Sons, Ltd.
New thermally stable and organosoluble heterocyclic poly(naphthaleneimide)s
Authors: Damaceanu Mariana‐Dana , Rusu Radu‐Dan , Bruma Maria , Rusanov Alexander L.
Published: August 2009

As majority of polyheteroarylenes based on bis(naphthalic anhydrides), are difficult to process due to their infusiblity and insolubility in common organic solvents and solubility only in strong acids, this study is concerned with the synthesis and properties of new, easily processable polyimides and copolyimides containing naphthalene and oxadiazole rings. These polymers have been synthesized and their properties have been compared with regard to the influence of oxadiazole and naphthalene units on their physical properties. The polyimides were prepared by polycondensation reaction in solution of the aromatic diamines containing preformed oxadiazole ring with two dianhydrides having naphthalene units, at high temperature. Also, copolyimides were prepared by using a mixture of each naphthalene‐containing dianhydride, with hexafluoroisopropylidene‐dianhydride in the polycondensation reaction with the same diamino‐oxadiazoles. Most of the resulting polyimides and copolyimides were soluble in polar amidic solvents and in less polar solvents, and their solutions gave flexible films when spread onto glass plates. The thermal stability and glass transition temperature of these polyimides and copolyimides were measured and compared. The quality and the roughness of the spin‐coated films of these polymers were investigated by atomic force microscopy. The photoluminescence properties of the polymers in solution were studied to determine the color of emission. The UV absorption was also studied to determine the Stokes shift, and hence the possible reabsorption effects. The properties of the present polyimides make them attractive for applications in advanced optoelectronics and other related fields. Copyright © 2009 John Wiley & Sons, Ltd.
Bilateral gonadoblastoma with dysgerminoma and pilocytic astrocytoma with WT1 GT‐IVS9 mutation: A 46 XY phenotypic female with Frasier syndrome
Authors: Subbiah Vivek , Huff Vicki , Wolff Johannes E.A. , Ketonen Leena , Lang Frederick F. , Stewart John , Langford Lauren , Herzog Cynthia E.
Published: August 2009

Frasier syndrome is characterized by a 46 XY disorder of sex development, nephropathy, and increased risk for gonadoblastoma due to Wilms tumor 1(WT1) mutation in the donor splice site of intron‐9, resulting in the splice form +KTS. Germ cell tumors and gonadoblastomas have been reported previously in Frasier syndrome. We present the clinical, radiological, and genetic (WT1 mutation analysis) of a 46 XY phenotypic female with Frasier syndrome with bilateral gonadoblastoma with dysgerminoma who developed pilocytic astrocytoma. Pediatr Blood Cancer 2009; 53:1349–1351. © 2009 Wiley‐Liss, Inc.
Synthesis and characterization of poly(lactic acid) and aliphatic polycarbonate copolymers
Authors: Yu Tao , Ren Jie , Gu Shuying , Yang Ming
Published: August 2009

BACKGROUND: Poly(lactic acid) (PLA) has received much attention as a biodegradable polymer. But the physical properties of PLA, such as brittleness, limit its wider applicability. Copolymerization polymers ing soft blocks provides a useful method to improve the mechanical properties of PLA.

RESULTS: Poly(lactic acid)‐block‐(polycarbonate diol) (PLA‐PCD) copolymers were synthesized using a two‐step process with polycondensation and chain extension reactions. The effect of polycarbonate diol content on the prepolymer properties was studied. The chain‐extended products were characterized using 1H NMR, F and. The effect of the NCO/OH ratio on the properties of the chain‐extended products, including the mechanical properties and thermal properties, was studied. eight‐average molecular weight of the product can reach 210 000 g mol−1 when the molar ratio of NCO to OH is 3:1.

CONCLUSION: The PLA‐PCD copolymers obtained can crystallize, and the crystallinity decreases with chain‐extension reaction. The products exhibit superior mechanical properties with elongation at break above 230%, which is much higher than that of PLA chain‐extended products. The products have a good potential for packaging applications. Copyright © 2009 Society of Chemical Industry
Reactivity of acrylamide as an alkylating agent: a kinetic approach
Authors: Céspedes‐Camacho Isaac F. , Manso José A. , Pérez‐Prior M. Teresa , Gómez‐Bombarelli Rafael , González‐Pérez Marina , Calle Emilio , Casado Julio
Published: August 2009

Acrylamide (AA), an industrially produced reactive molecule, is used worldwide. The US EPA and IARC have classified this molecule as a probable human carcinogen. In this work, the alkylating potential of AA was investigated kinetically. The conclusions drawn are as follows: (i) AA shows alkylating ability on the nucleophile 4‐(p‐nitrobenzyl)pyridine (NBP), a trap for alkylating agents with nucleophilic characteristics similar to those of DNA bases; (ii) the rate equation for the NBP–AA adduct formation is as follows: $r = k_{{\rm alk}} \left[ {{\rm AA}} \right]\left[ {{\rm NBP}} \right]$; (ii) the thermoentropic term, TΔ‡Sθ, is the main term responsible for the lower reactivity of AA as an alkylating agent; (iii) the value of the Gibbs energy of activation, Δ‡Gθ, for the NBP alkylation reaction by AA is consistent with the conclusions of epidemiologic studies concerning the carcinogenicity of this substance; (iv) the results obtained here may be useful when working with hydrophilic/lipophilic media, such as in Food Science, since the dielectric constant of the medium, where alkylation occurs, influences the reaction rate, and alkylation can be inhibited by lowering the dielectric constant of the medium. Copyright © 2009 John Wiley & Sons, Ltd.
Silver metal nanoparticles: Facile dendrimer‐assisted size‐controlled synthesis and selective catalytic reduction of chloronitrobenzenes
Authors: Sutton Amy , Franc Grégory , Kakkar Ashok
Published: August 2009

A simple and versatile synthetic methodology to silver metal nanoparticles that utilizes 3,5‐dihydroxybenzyl alcohol‐based dendrimers as templates and does not necessitate the addition of any external reducing agent is reported. An evaluation of the role of addition rate of the silver acetate solution, and the dendrimer to silver acetate molar ratio, as well as the dendritic effect on nanoparticle growth, suggests that the size of these metal nanoparticles can be controlled by simple variations of these parameters. A probe of the mechanism of the nanoparticle formation and growth indicates that the terminal hydroxyl groups of the dendrimers play a major role in metal ion isolation and reduction, in addition to providing stabilization to the growing metal particles. These silver metal nanoparticles are highly active catalysts for the selective reduction of chloronitrobenzenes to chloroanilines. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4482–4493, 2009
Synthesis of well‐defined azide‐terminated poly(vinyl alcohol) and their subsequent modification via click chemistry
Authors: Tong Yin‐Yin , Wang Rui , Xu Ning , Du Fu‐Sheng , Li Zi‐Chen
Published: August 2009

A new azide‐functionalized xanthate, S‐(4‐azidomethylbenzyl) O‐(2‐methoxyethyl) xanthate, was synthesized and used to mediate the reversible addition fragmentation chain transfer polymerization of vinyl acetate. The polymerization was demonstrated to be controlled, and well‐defined PVAc with α‐azide, ω‐xanthate groups were obtained, the xanthate groups of which were further removed by radical‐induced reduction with lauroyl peroxide in the presence of excess 2‐propanol. Hydrolysis of α‐azide‐terminated PVAc (N3‐PVAc) led to the formation of the corresponding α‐azide‐terminated PVA (N3‐PVA). Finally, end‐modification of N3‐PVA by click chemistry with alkyne‐end‐capped poly(caprolactone) (A‐PCL), alkynyl‐mannose, and alkynyl‐pyrene was carried out to obtain a new block copolymer PCL‐b‐PVA, and two PVA with mannose or pyrene as the end functional groups. The polymers were characterized by gel permeation chromatography, 1H NMR spectroscopy, and FTIR. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4494–4504, 2009
Controlled reduction of polypropylene isotacticity and crystallinity by epimerization during reactive processing
Authors: Henry Gaëtan R. P. , Drooghaag Xavier , Vandeuren Mikhaël , Sclavons Michel , Schanck André , Devaux Jacques , Carlier Véronique , Marchand‐Brynaert Jacqueline
Published: August 2009

Amorphous and low crystallinity polypropylenes were produced by reactive processing of commercial isotactic polypropylenes in the presence of a peroxide (2,5‐dimethyl‐2,5‐di(tert‐butylperoxy)hexane) and N‐bromosuccinimide. Characterization of the modified polypropylene microstructures using 13C NMR spectroscopy revealed that crystallinity loss is correlated with the epimerization of numerous methynes randomly along the polymer backbone, leading to decreasing isotacticities ([mmmm]) and average isotactic block lengths. Moreover, degradation usually induced by peroxide was shown to be comparatively limited in additional presence of N‐bromosuccinimide. This fast and easy process therefore allows the production of polypropylene plastomers and elastomers with controlled and homogeneous crystallinities and isotacticities, and relatively low molecular weight distributions. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4505–4518, 2009
Study of electrical, mechanical, and nanoscale free‐volume properties of NBR and EPDM rubber reinforced by bentonite or kaolin
Authors: EL‐Nashar D. E. , Gomaa E. , Abd‐El‐Messieh S. L.
Published: August 2009

The effect of Na bentonite, Ca bentonite, and kaolin fillers on the macrostructure and microstructure of acrylonitrile butadiene rubber, ethylene propylene diene rubber, and their blend (50/50) was studied through electrical and mechanical measurements, as well as with positron annihilation lifetime spectroscopy. The real part of permittivity (ε′), dielectric loss (ε″), and the crosslinking density were found to increase with increasing filler content. The increase of crosslinking density of the blend with increasing amount of fillers reflects a decrease in the equilibrium swelling up to 21.50 wt % compared with that of the unfilled blends. The mechanical investigation showed pronounced increase in the tensile strength, and in elongation at break with the addition of up to 21.50 wt % of filler. In addition, comparing between different fillers showed that the reinforcing effect of Na bentonite is more effective than Ca bentonite and kaolin but the physico‐mechanical of Ca bentonite is less than that for kaolin. The positron annihilation lifetime measurements revealed that the free‐volume properties were strongly affected by the amount and type of filler, in particular, the free‐volume fraction was dramatically decreased with increasing filler content. Furthermore, correlations were made between the free‐volume parameters and both electrical and mechanical properties. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1825–1838, 2009
Self‐association of cellulose ethers with random and regioselective distribution of substitution
Authors: Sun Shaomin , Foster Timothy J. , MacNaughtan William , Mitchell John R. , Fenn Dominik , Koschella Andreas , Heinze Thomas
Published: August 2009

2 to 4% aqueous solutions of regioselectively substituted 3‐mono‐O‐ethyl‐ (3‐EC) and randomly substituted ethyl‐ (EC) cellulose show association and gelation above 50–60 and 20–30 °C, respectively. In contrast, almost no association or gelation was seen with regioselectively substituted 3‐mono‐O‐methoxyethyl cellulose (3‐MEC). This could be assessed by eye and measured using the techniques of 1H high‐resolution nuclear magnetic resonance, oscillatory rheology, and micro‐differential scanning calorimetry (DSC). Several processes are thought to occur during association and gelation of EC and 3‐EC. These were separated with respect to temperature, to varying degrees, on cooling and have been modeled using DSC data. In accordance with other work in the literature, they are thought to be, on heating, the disassociation of structures in solution followed first by the formation of water cages and then by the association of hydrophobic moieties into a precipitate or gel. Contrasting with previous work (Haque and Morris, Carbohydr Polym 1993, 22, 161–173), the rheological measurements do not show “two distinct waves of structure formation” at the present concentrations and the DSC measurements show, on cooling, an extremely wide separation in temperature of the processes for the regioselectively substituted cellulose derivative 3‐EC. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1743–1752, 2009
Physical aging and structural relaxation in polymer nanocomposites
Authors: Liu Amy Y.‐H. , Rottler Jörg
Published: August 2009

Molecular dynamics simulations of a coarse‐grained polymer nanocomposite model are used to study the impact of nanoparticles on physical aging. The physical aging rate of the composites is obtained from measurements of the per‐particle pair energy, while the (segmental) mean‐squared displacement and creep compliance are used to probe simultaneously the dependence of structural relaxation times on waiting time elapsed since the glass was formed. Although bulk regions behave similarly to a neat polymer glass, interfacial regions exhibit a reduction in the physical aging rate for attractive polymer–nanoparticle interactions. Repulsive interactions lead instead to a significant increase. This change in physical aging rate is found to be proportional to the local mobility of the polymer atoms. By contrast, aging exponents obtained from time‐waiting time superposition of mean‐squared displacements or compliance curves are much less affected by the nanoinclusions. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1789–1798, 2009
Thermodynamic and kinetic thermal analyses on dual crystal forms in polymorphic poly(heptamethylene terephthalate)
Authors: Yen Kai‐Cheng , Woo Eamor M.
Published: August 2009

Thermal analyses were performed for determining the equilibrium melting temperatures T of the respective α‐ and β‐crystal in melt‐crystallized polymorphic poly(heptamethylene terephthalate) (PHepT) using both linear and nonlinear Hoffman‐Weeks (H‐W) methods for comparison of validity. These two crystals in PHepT do not differ much in their melting temperatures. The equilibrium melting temperatures of the α‐ and β‐crystal as determined by the linear H‐W method are 98 °C and 100.1 °C, respectively; but the nonlinear H‐W method yielded higher values for both crystals. The equilibrium melting temperatures of the α‐ and β‐crystal according to the nonlinear H‐W method are 121 °C and 122.5 °C, respectively. Both methods consistently indicate that T of the β‐crystal is only slightly higher than that of the α‐crystal. Such small difference in T between the α‐ and the β‐crystal causes difficulties in judging the relative thermodynamic stability of these two crystals. Thus, kinetics of these two crystals was compared using the Avrami and Ozawa theory. The crystallization produced by quenching from Tmax = 110 °C and 150 °C shows a heterogeneous and homogeneous nucleation mechanism, respectively. The lower Tmax = 110 °C leads to heterogeneous nucleation and only α‐crystal in PHepT, whose crystallization rates at same Tc are much higher than crystallization rates by quenching from Tmax = 150 °C leading to either α‐ or β‐crystal with homogeneous nucleation. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1839–1851, 2009
Structure and electrostatic property of cytoplasmic domain of ZntB transporter
Authors: Tan Kemin , Sather Alicia , Robertson Janice L. , Moy Shiu , Roux Benoît , Joachimiak Andrzej
Published: August 2009

ZntB is the distant homolog of CorA Mg2+ transporter within the metal ion transporter superfamily. It was early reported that the ZntB from Salmonella typhimurium facilitated efflux of Zn2+ and Cd2+, but not Mg2+. Here, we report the 1.90 Å crystal structure of the intracellular domain of ZntB from Vibrio parahemolyticus. The domain forms a funnel‐shaped homopentamer that is similar to the full‐length CorA from Thermatoga maritima, but differs from two previously reported dimeric structures of truncated CorA intracellular domains. However, no Zn2+ or Cd2+ binding sites were identified in the high‐resolution structure. Instead, 25 well‐defined Cl− ions were observed and some of these binding sites are highly conserved within the ZntB family. Continuum electrostatics calculations suggest that the central pore of the funnel is highly attractive for cations, especially divalents. The presence of the bound Cl− ions increases the stability of cations along the pore suggesting they could be important in enhancing cation transport.
Proligands with protease‐regulated binding activity identified from cell‐displayed prodomain libraries
Authors: Thomas Jerry M. , Daugherty Patrick S.
Published: August 2009

A general method was developed for the discovery of protease‐activated binding ligands, or proligands, from combinatorial prodomain libraries displayed on the surface of E. coli. Peptide libraries of candidate prodomains were fused with a matrix metalloprotease‐2 substrate linker to a vascular endothelial growth factor‐binding peptide and sorted using a two‐stage flow cytometry screening procedure to isolate proligands that required protease treatment for binding activity. Prodomains that imparted protease‐mediated switching activity were identified after three sorting cycles using two unique library design strategies. The best performing proligand exhibited a 100‐fold improvement in apparent binding affinity after exposure to protease. This method may prove useful for developing therapeutic and diagnostic ligands with improved systemic targeting specificity.
Early antiallergic inflammatory effects ofRhus vernicifluastokes on human mast cells
Authors: Hong Myung Hee , Kim Jeong‐Hyun , Lee Sea Yun , Go Ho Yeon , Kim Ji Hye , Shin Yong‐Cheol , Kim Sung‐Hoon , Ko Seong‐Gyu
Published: August 2009

Rhus vernicifluaStokes (RVS) is a traditional medicine used in Korea, Japan and China to treat various diseases including catharsis, diaphoretic gastritis and stomach cancer. However, the effects of RVS on allergic inflammatory diseases are unknown to date. This study showed the antiallergic inflammatory effects of RVS on human mast cells (HMC‐1) which were stimulated by phorbol myristate acetate (PMA) and calcium ionophore A23187. RVS inhibited the expressions of TNF‐α, IL‐6 and IL‐8 that were stimulated by treatment with both PMA and A23187. Among the mitogen‐activated protein kinases (MAPKs), extracts of RVS suppressed the phosphorylation of ERK and p38, whereas RVS increased the phosphorylation of JNK in HMC‐1. Consistent with the regulation of MAPKs, it was found that RVS inhibited the nuclear translocation of nuclear factor (NF)‐κB via inhibition of the phosphorylation of IκB‐α, which are important processes in controlling inflammatory responses. Taken together, these results suggest that RVS modulates the expressions of signal molecules related to allergic inflammatory responses mainly through the ERK signaling pathway, suggesting that RVS could be used as a treatment for mast cell‐derived allergic inflammatory diseases. Copyright © 2009 John Wiley & Sons, Ltd.
Antiproliferative effect of benzophenones and their influence on cathepsin activity
Authors: Murata Ramiro Mendonça , Yatsuda Regiane , dos Santos Marcelo Henrique , Kohn Luciana K. , Martins Felipe Terra , Nagem Tanus Jorge , Alencar Severino Matias , de Carvalho João Ernesto , Rosalen Pedro Luiz
Published: August 2009

The antiproliferative activity of two prenylated benzophenones isolated from Rheedia brasiliensis, the triprenylated garciniaphenone and the tetraprenylated benzophenone 7‐epiclusianone, was investigated against human cancer cell lines. The antiproliferative activity on melanoma (UACC‐62), breast (MCF‐7), drug‐resistant breast (NCI‐ADR), lung/non‐small cells (NCI460), ovarian (OVCAR 03), prostate (PC03), kidney (786‐0), lung (NCI‐460) and tongue (CRL‐1624 and CRL‐1623) cancer cells was determined using spectrophotometric quantification of the cellular protein content. The effect of these benzophenones on the activity of cathepsins B and G was also investigated. Garciniaphenone displayed cytostatic activity in all cell lines, whereas 7‐epiclusianone showed a dose‐dependent cytotoxic effect. The IC50 values for cell proliferation revealed that 7‐epiclusianone is more active than garciniaphenone against most of the cell lines. Furthermore, the antiproliferative effects demonstrated by garciniaphenone and 7‐epiclusianone were related to their cathepsin inhibiting properties. In conclusion, 7‐epiclusianone is a promising naturally occurring agent which displays multiple inhibitory effects which may be working in concert to inhibit cancer cell proliferation in vitro. The putative pathway by which 7‐epiclusianone affects cancer cell development may involve cathepsin inhibition. Copyright © 2009 John Wiley & Sons, Ltd.
Protective effect of Astragalus polysaccharides on ATP binding cassette transporter A1 in THP‐1 derived foam cells exposed to tumor necrosis factor‐alpha
Authors: Wang Yan‐Fu , Yang Xiao‐Fang , Cheng Bei , Mei Chun‐Li , Li Qing‐Xian , Xiao Hua , Zeng Qiu‐Tang , Liao Yu‐Hua , Liu Kun
Published: August 2009

Astragalus polysaccharide (APS), the main extract from the traditional Chinese medicinal herb Astragalus membranaceus, has been reported to benefit the treatment of immune‐inflammatory diseases and metabolic disorders. In atherosclerotic plaques, proinflammatory cytokines exert adverse effects on lipids thereby aggravating atherosclerosis. Recent evidence shows that tumor necrosis factor‐alpha (TNF‐α) can down‐regulate the expression of ATP‐binding cassette transporter A1 (ABCA1), which plays a vital role in reverse cholesterol transport and determines the process of atherosclerosis. In the present study, the effects of APS on ABCA1 expression, cholesterol effluent rate and total cholesterol content of THP‐1 derived foam cells exposed to TNF‐α were investigated. Compared with the foam cells exposed to TNF‐α, ABCA1 expression was promoted in the presence of APS. Consequently the cholesterol effluent rate increased and the total cholesterol content decreased significantly. TNF‐α could enhance the activity of nuclear factor‐kappa B (NF‐κB) in the foam cells. This effect could be attenuated by APS. These findings suggest that APS could protect ABCA1 against the lesion of TNF‐α in THP‐1 derived foam cells, which may contribute to its antiatherosclerotic properties. Copyright © 2009 John Wiley & Sons, Ltd.
Protective effects of steroids from Allium chinense against H2O2‐induced oxidative stress in rat cardiac H9C2 cells
Authors: Ren Gang , Qiao Hong Xiang , Yang Jun , Zhou Chang Xin
Published: August 2009

Allium chinense, a traditional herbal medicine, has been used for the treatment of cardiovascular diseases for hundreds of years. In this study, A. chinense steroids (ACSs) including three steroidal glycosides and their parent aglycones were isolated from the bulbs of A. chinense. For the first time, their cardioprotective effects were evaluated in cultured rat cardiac H9C2 cells by pretreatment with ACSs for 24 h before exposure to 0.2 mm H2O2. The results showed the cell viability decreased markedly when H9C2 cells were incubated with 0.2 mm H2O2 alone for 2 h, while the cell lipid peroxidation (estimated by the excessive production of nitric oxide and malondialdehyde) and intracellular free calcium concentration ([Ca2+]i) increased significantly. The addition of 20 μm (below the toxic concentration) of ACSs notably attenuated the cellular injury induced by H2O2. The effects of ACSs in our experiments were similar to those of nimodipine, a clinically applied calcium channel blocker. Preliminary analysis of the structure–activity relationship indicated that ACSs with a spirostane‐type skeleton exhibited stronger protection than that with a furostane‐type skeleton, and glycosylation of the steroids could substantially lower the protective activities. The above results suggested the protective effects of steroids originated from A. chinense on the oxidative injury of H9C2 cells and ACSs may have potential for preventing cardiac injuries induced by oxidative stress. Copyright © 2009 John Wiley & Sons, Ltd.