bluuebunny/crossref_metadata_2025 huggingface dataset:
A selective reaction of fructose bisphosphate aldolase with fluorescein isothiocyanate in chicken muscle extracts
Authors: Gehring Andrew G. , Ezzell John L. , Lebherz Herbert G.
Published: April 2008

The present work describes the selective covalent modification of fructose bisphosphate aldolase in crude extracts of chicken breast muscle by fluorescein 5′‐isothiocyanate (5′‐FITC) at pH 7.0 and 35°C. The modification was observed after 1 min while no other major soluble protein was labeled even after 30 min. We calculated that ca. one 5′‐FITC molecule was incorporated into each aldolase tetramer after a 30 min reaction which resulted in a minimal loss of enzyme activity. The “native” structure of aldolase was required for the selective modification by 5′‐FITC since high pH, high temperature, and ionic detergents either inhibited or prevented the reaction of 5′‐FITC with aldolase. Certain metabolites (ATP, ADP, CTP, GTP, FBP) and erythrosin B also inhibited the 5′‐FITC modification of aldolase. In contrast, F‐6‐P, AMP, NADH, and NAD+ as well as free lysine and most importantly, the 6′‐isomer of FITC exhibited no competition with 5′‐FITC for the labeling of aldolase. Alone, the 6′‐isomer of FITC did not exhibit preferential reaction when combined with aldolase. 5′‐FITC‐labeled and ‐unlabeled aldolases were not distinguished by their ability to bind to muscle myofibrils (MFs) or by their abilities to refold following reversible denaturation in urea. Structural analysis revealed that 5′‐FITC‐labeled a tryptic peptide corresponding to residues 112–134 in the primary structure of aldolase, a peptide that does not contain lysine, the amino acid believed to be the primary target of this reagent. Unlike chicken and rabbit muscle aldolases, chicken brain and liver aldolase isoforms along with several other aldolases derived from diverse biological sources did not exhibit this highly selective modification by 5′‐FITC. Copyright © 2008 John Wiley & Sons, Ltd.
Biomimetic affinity purification of cardiotoxin and its pharmacological effects on the nervous system
Authors: Dong Dexian , Liu Haoran , Xiao Qishi , Wang Ting , Liu Huaqing , Li Rongxiu
Published: April 2008

Cobra venom is a very precious natural resource. The traditional method for purification of cardiotoxin from cobra venom is a multi‐step, high cost, and low recovery procedure. By molecular modeling and docking with SYBYL software, we designed and synthesized an affinity ligand, m‐aminobenzoic acid, for high efficiency purification of this therapeutically useful Chinese cobra venom cardiotoxin. The one‐step recovery of cardiotoxin reached 64% and the purity reached 92% upon purification. The binding capacity of this synthetic ligand was 9.1 mg cardiotoxin/g moist weight gel and the affinity constant for cardiotoxin was 5.5 × 103 M−1. Unlike a natural affinity ligand, this synthetic ligand is highly stable, and has great potential for industrial scale production of cardiotoxin. In addition, we examined the effects of cardiotoxin on the nervous system in a mouse model. Results showed that cardiotoxin could maintain analgesic effects for 120 min with a dose of less than 0.06 mg/kg (2.8% of the LD50). Administration of 0.12 mg/kg cardiotoxin could improve scopolamine impairments of memory in mice. These results suggest that cardiotoxin may be a potential drug for nervous system diseases. Copyright © 2008 John Wiley & Sons, Ltd.
Synthesis and ITC characterization of novel nanoparticles constituted by poly(γ‐benzyl L‐glutamate)‐β‐cyclodextrin
Authors: Barbosa Ma. Elisa Martínez , Bouteiller Laurent , Cammas‐Marion Sandrine , Montembault Véronique , Fontaine Laurent , Ponchel Gilles
Published: April 2008

Imparting desired technological characteristics to polymeric nanoparticles requires the development of original polymers. In the present work, the synthesis and characterization of a novel PBLG‐derivative, the poly(γ‐benzyl L‐glutamate)‐β‐cyclodextrin (PBLG‐β‐CD‐50), have been carried out. Nanoparticles from either PBLG‐β‐CD‐50 polymer or from mixtures with PBLG have been prepared using a modified nanoprecipitation method. Spherically shaped nanoparticles with diameter in the range of 50–70 nm were obtained, as determined by dynamic laser light scattering and transmission electron microscopy. The presence of a surfactant in the suspension medium had almost no influence on these parameters and was not necessary to the shelf‐stability of the suspension. Further, isothermal titration microcalorimetry (ITC) experiments have been used to show unambiguously that about 20% of the cyclodextrins remain functional within the particles. Consequently, this system may be of interest when association of large amounts of hydrophobic drugs to nanoparticles is required. Copyright © 2008 John Wiley & Sons, Ltd.
Activation of the extracellular signal‐regulated kinases 1 and 2 by glial cell line‐derived neurotrophic factor and its relation to neuroprotection in a mouse model of Parkinson's disease
Authors: Lindgren Niklas , Leak Rehana K. , Carlson Kirsten M. , Smith Amanda D. , Zigmond Michael J.
Published: April 2008

Glial cell line‐derived neurotrophic factor (GDNF) has been shown to be neuroprotective in animal models of the dopamine deficiency in Parkinson's disease. To examine the role of the extracellular signal‐regulated kinases 1 and 2 (ERK1/2) in this process, we infused a single dose of GDNF into the striatum of mice and analyzed the effect on ERK1/2 by immunohistochemistry and Western blot analysis. GDNF caused an increase in the phosphorylation of ERK1/2 both in the striatum and in tyrosine hydroxylase‐positive neurons in the substantia nigra. In the striatum, the increase in ERK1/2 phosphorylation was evident by 3 hr and persisted for at least 7 days, whereas, in the substantia nigra, an increase in phosphorylated ERK1/2 was first evident at 24 hr and persisted for at least 7 days. The increase in phosphorylated ERK1/2 was maximal at 0.45 μg GDNF at the time points examined. GDNF also protected dopamine terminals against the loss of tyrosine hydroxylase immunoreactivity normally associated with the intrastriatal administration of 6‐hydroxydopamine (0.5 μg/0.5 μl). However, this was observed only at a much higher dose of GDNF, 4.5 μg. Thus, our results suggest that the ability of GDNF to protect dopamine neurons cannot be explained solely in terms of its influence on ERK1/2 and that the role of other signaling pathways should be explored. © 2008 Wiley‐Liss, Inc.
Variability in sea‐surface temperature and winds in the tropical south‐east Atlantic Ocean and regional rainfall relationships
Authors: Hermes J. C. , Reason C. J. C.
Published: April 2008

Variability in sea‐surface temperature (SST) and winds in the Angola Benguela frontal zone (ABFZ) in the tropical south‐east Atlantic Ocean has previously been shown to be important for regional fisheries and for seasonal rainfall anomalies over Angola/Namibia in austral summer and coastal West Africa in boreal summer. This study investigates intraseasonal variability in winds and SST over this region using QuikSCAT and tropical rainfall measuring mission (TRMM) satellite data for 1999–2004. Wavelet analyses reveal periods of relatively strong power in the 20–30 or 30–64 day frequency bands throughout the record but that there is substantial interannual variability in the occurrence of these intraseasonal oscillations. The implications of this variability for seasonal rainfall anomalies during the main rainy seasons in southern Africa (austral summer) and coastal West Africa (boreal summer) are discussed. Copyright © 2008 Royal Meteorological Society
Raman spectroscopy of ionic liquids derived from 1‐n‐butyl‐3‐methylimidazolium chloride and niobium chloride or zinc chloride mixtures
Authors: Alves Melquizedeque B. , Santos jr. Vianney O. , Soares Valerio C. D. , Suarez Paulo A. Z. , Rubim Joel C.
Published: April 2008

Anionic species formed in mixtures of 1‐n‐butyl‐3‐methylimidazolium chloride (BMICl) with different amounts of niobium pentachloride (NbCl5) or zinc dichloride (ZnCl2) were investigated by Raman spectroscopy. In the BMICl and NbCl5 ionic mixtures the presence of the anion NbCl6− was detected for all compositions (molar fraction, X) and a mixture of this anion and the neutral Nb2Cl10 in acid ones. Two different anions were observed for basic mixtures of BMICl and ZnCl2: ZnCl42−(0 < X < 0.35) and Zn2Cl62−(X > 0.3), whereas for acidic ones three species were detected: Zn2Cl62−(X < 0.7), Zn3Cl82−(X > 0.7) and Zn4Cl102−(X > 0.7). It has also been observed that in both cases, the formation of larger anions causes a shift of the CH stretching modes to higher wavenumbers as the result of a decrease in the hydrogen bond between Cl and the hydrogens from the cation. Copyright © 2008 John Wiley & Sons, Ltd.
Chromatographic deuterium isotope effects of derivatized N‐glycans and N‐glycopeptides in a zwitterionic type of hydrophilic interaction chromatography
Authors: Takegawa Yasuhiro , Hato Megumi , Deguchi Kisaburo , Nakagawa Hiroaki , Nishimura Shin‐Ichiro
Published: April 2008

HPLC/MS is now an essential method for the analysis of glycans and glycopeptides. A technique using ICATs is also becoming popular for their comparative/quantitative analysis based on MS signal intensities. However, the RP HPLC most often used causes “doublet” peaks of deuterium‐labeled and nonlabeled peptides, which are well known for causing the chromatographic deuterium isotope effect. Such doublet peaks are undesirable for precise comparison of MS signal intensities. This report shows that, in the zwitterionic type of hydrophilic interaction chromatography, the chromatographic deuterium isotope effect is negligibly small for N‐glycans derivatized with deuterium‐labeled 2‐aminopyridine and N‐glycopeptides derivatized with deuterium‐labeled succinic anhydride.
Multiple linear regression and artificial neural network retention prediction models for ginsenosides on a polyamine‐bonded stationary phase in hydrophilic interaction chromatography
Authors: Quiming Noel S. , Denola Nerissa L. , Saito Yoshihiro , Jinno Kiyokatsu
Published: April 2008

The development of retention prediction models for the seven ginsenosides Rf, Rg1, Rd, Re, Rc, Rb2, and Rb1 on a polyamine‐bonded stationary phase in hydrophilic interaction chromatography (HILIC) is presented. The models were derived using multiple linear regression (MLR) and artificial neural network (ANN) using the logarithm of the retention factor (log k) as the dependent variable for four temperature conditions (0, 10, 25, and 40°C). Using stepwise MLR, the retention of the analytes in all the temperature conditions was satisfactorily described by a two‐predictor model wherein the predictors were the percentage of ACN (%ACN) in the mobile phase and local dipole index (LDI) of the compounds. These predictors account for the contribution of the solute‐related variable (LDI) and the influence of the mobile phase composition (%ACN) on the retention behavior of the ginsenosides. A comparison of the models derived from both MLR and ANN revealed that the trained ANNs showed better predictive abilities than the MLR models in all temperature conditions as demonstrated by their higher R2 values for both training and test sets and lower average percentage deviation of the predicted log k from the observed log k of the test compounds. The ANN models also showed excellent performance when applied to the prediction of the seven ginsenosides in different sample matrices.
Fiberlaser: Beam Sources and Applications
Authors: Hoult Tony , Gabzdyl Jack
Published: April 2008

The worldwide acceptance of anthropogenic global warming has brought a dramatically increased interest in renewable energy resources. This trend led to some interesting developments related to photovoltaics. Firstly, current manufacturing capacity using bulk silicon has grown significantly and caused a worldwide shortage of silicon. Secondly, newer thin film PV (photovoltaic) technology has been pushed forward dramatically, not at least due to the rising cost of silicon. But beside that, the rapid growth of the photovoltaics industry requires new processes where laser technology may obtain a crucial role.
Health benefits of omega‐3 fatty acids from Neptune krill oil
Authors: Massrieh Wael
Published: April 2008

Over the last few decades, natural health ingredients have gained the interest and support of both science and industry. The increasing incidence of adverse events associated with synthetic drugs has created a demand for effective and safe alternative treatments. The few natural health ingredients that have been rigorously researched for their safety and efficacy and have passed both peer and regulatory scrutiny can provide a solution to this problem. Neptune krill oil® (NKO®) fulfills these criteria by supporting solid scientifically validated research proving safety and efficacy. Furthermore, the company is involved in several novel clinical trials to further expand its proprietary and innovative portfolio.
Jatropha curcas: A potential source for tomorrow' s oil and biodiesel
Authors: Becker Klaus , Makkar H. P. S.
Published: April 2008

Greenhouse gas emission (GHG) is the driving force for global climate change. Deforestation accounts for over 20% of the world's GHG emission and leaves behind deforested areas. It is of utmost importance to revert these areas in a way that carbon is sequestered again. Jatropha curcas, a perennial tree or shrub, is capable of growing on such degraded land and eventually reclaim it. In addition to providing biodiesel of high quality it has several other uses of economic importance. There is an edible genotype of J. curcas that exclusively grows in Mexico. Fatty acid composition of both toxic and non‐toxic genotypes mirrors that of most conventional plant oils used for biodiesel production. Biodiesel produced from J. curcas oil meets all the requirements stipulated by the EU‐Standard EN‐14214. As J. curcas is still a wild plant, initiation of systematic selection and breeding programmes is a prerequisite for sustainable utilization of this plant for oil and biodiesel production.
Olfactory pathogenesis of idiopathic Parkinson disease revisited
Authors: Lerner Alicja , Bagic Anto
Published: April 2008

Idiopathic Parkinson disease (PD) is traditionally considered a movement disorder with hallmark lesions located in the substantia nigra pars compacta (SNpc). However, recent histopathological studies of some PD cases suggest the possibility of a multisystem disorder which progresses in a predictable sequence as described in Braak's staging criteria. The disease process starts in the dorsal motor nucleus of the vagus (dmX) and anterior olfactory nucleus and bulb, and from there, spreads through the brainstem nuclei to ultimately reach the SNpc, which then presents as symptomatic PD. In this article, we would like to revisit the olfactory pathogenesis of PD based on Braak's staging system and review anatomical pathways supporting such a possibility. We also suggest some biomarkers for early stages of PD. Additionally, we present and discuss the possibility that a prion‐like process underlies the neurodegenerative changes in PD. © 2008 Movement Disorder Society
The diet‐derived sulforaphane inhibits matrix metalloproteinase‐9‐activated human brain microvascular endothelial cell migration and tubulogenesis
Authors: Annabi Borhane , Rojas‐Sutterlin Shanti , Laroche Mathieu , Lachambre Marie‐Paule , Moumdjian Robert , Béliveau Richard
Published: April 2008

Human brain microvascular endothelial cells (HBMECs) play an essential role as structural and functional components of the blood–brain barrier (BBB). While disruption of the BBB by the brain tumor‐secreted matrix metalloproteinase‐9 (MMP‐9) favors tumor invasion, the role and regulation of MMP‐9 secretion by HBMEC themselves in response to carcinogens or brain tumor‐derived growth factors has received little attention. Our study delineates a unique brain endothelial phenotype in that MMP‐9 secretion is increased upon phorbol 12‐myristate 13‐acetate (PMA) treatment of HBMEC. Sulforaphane (SFN), an isothiocyanate present in broccoli which exhibits chemopreventive properties, selectively inhibited the secretion of MMP‐9 but not that of MMP‐2. The decrease in MMP‐9 gene expression correlated with a decrease in the expression of the mRNA stabilizing factor HuR protein triggered by SFN. PMA‐induced HBMEC migration was also antagonized by SFN. Silencing of the MMP‐9 gene inhibited PMA‐induced MMP‐9 secretion, cell migration, and in vitro tubulogenesis on Matrigel. While SFN inhibited the chemoattractive abilities of brain tumor‐derived growth factors, it failed to inhibit PMA‐induced tubulogenesis. Our data are indicative of a selective role for SFN to inhibit MMP‐9‐activated, but not basal, HBMEC migration, and tubulogenesis whose actions could add to SFN's antitumor properties.
Relative signs of 29Si13C couplings
Authors: Blechta Vratislav , Schraml Jan
Published: April 2008

Two pulse sequences applicable to the determination of relative signs of coupling constants, gHSQC‐RELAY(P) and gHSQC‐RELAY(D), were developed and tested. These sequences are suitable for determination of relative signs of long‐range coupling constants (<2 Hz) between two heteronuclei of low abundance (such as 29Si and 13C), and are applicable even to cases in which one of the heteronuclei (29Si) does not exhibit coupling with some of the detected protons (1H). The two sequences differ in the manner in which they suppress undesirable homonuclear coherence transfers. Each of the sequences can be combined with an isotope filter for better suppression of the centerlines arising from more abundant NMR‐inactive isotopes. The sequences were tested on ethoxytrimethylsilane and (E)‐(buta‐1,3‐dienyloxy)trimethylsilane, and we conclude that 2J(29Si‐O‐13C) is positive while 3J(29Si‐O‐C‐13C) is negative in both compounds. Copyright © 2008 John Wiley & Sons, Ltd.
Frequency‐dependent tactile responses in rat brain measured by functional MRI
Authors: Sanganahalli Basavaraju G. , Herman Peter , Hyder Fahmeed
Published: April 2008

We measured frequency‐dependent functional MRI (fMRI) activations (at 11.7 T) in the somatosensory cortex with whisker and forepaw stimuli in the same α‐chloralose anesthetized rats. Whisker and forepaw stimuli were attained by computer‐controlled pulses of air puffs and electrical currents, respectively. Air puffs deflected (±2 mm) the chosen whisker(s) in the right snout in the rostral to caudal direction, and electrical currents (2 mA amplitude, 0.3 ms duration) stimulated the left forepaw with subcutaneous copper electrodes placed between the second and fourth digits. In the same subject, unimodal stimulation of whisker and forepaw gave rise to significant blood oxygen level‐dependent (BOLD) signal increases in corresponding contralateral somatosensory areas of whisker barrel field (S1BF) and forelimb (S1FL), respectively, with no significant spatial overlap between these regions. The BOLD responses in S1BF and S1FL regions were found to be differentially variable with frequency of each stimulus type. In the S1BF, a linear increase in the BOLD response was observed with whisker stimulation frequency of up to ∼12 Hz, beyond which the response seemed to saturate (and/or slightly attenuate) up to the maximum frequency studied (i.e. 30 Hz). In the S1FL, the magnitude of the BOLD response was largest at forepaw stimulation frequency between 1.5 and 3 Hz, beyond which the response diminished with little or no activity at frequencies higher than 20 Hz. The volume of tissue activated by each stimulus type followed a similar pattern to that of the stimulation frequency dependence. These results of bimodal whisker and forepaw stimuli in the same subject may provide a framework to study interactions of different tactile modules, with both fMRI and neurophysiology (i.e. inside and outside the magnet). Copyright © 2008 John Wiley & Sons, Ltd.
Connection and comparison between frequency shift time integration and a spectral transformation preconditioner
Authors: Meerbergen Karl , Coyette Jean‐Pierre
Published: April 2008

The numerical study of exterior acoustics problems is usually carried out in the frequency domain. Finite element analyses often require the solution of large‐scale algebraic linear systems. For very large problems, sometimes the time domain is used. Implicit time integration requires linear system solves, but these are often far easier than those from the frequency domain. This paper shows a connection between a spectral transformation preconditioner and a frequency shift time integration. This preconditioner is close to the shifted Laplace preconditioner. The preconditioned iterative method appears to be faster than time integration. Copyright © 2008 John Wiley & Sons, Ltd.
Approximating second‐order vector differential operators on distorted meshes in two space dimensions
Authors: Hermeline F.
Published: April 2008

A new finite volume method is presented for approximating second‐order vector differential operators in two space dimensions. This method allows distorted triangle or quadrilateral meshes to be used without the numerical results being too much altered. The matrices that need to be inverted are symmetric positive definite; therefore, the most powerful linear solvers can be applied. The method has been tested on a few second‐order vector partial differential equations coming from elasticity and fluids mechanics areas. These numerical experiments show that it is second‐order accurate and locking‐free. Copyright © 2008 John Wiley & Sons, Ltd.
On the computation of the coupled thermo‐electromagnetic response of continua with particulate microstructure
Authors: Zohdi T. I.
Published: April 2008

Recently, several applications, primarily driven by micro‐technology, have emerged where the use of materials with tailored electromagnetic properties is necessary for a successful design. The ‘tailored’ properties are achieved by doping an easily moldable base matrix with particles having dielectric constants that are chosen to give overall desired properties. In many cases, the analysis of such materials requires the simulation of the macroscopic and microscopic electromagnetic response, as well as its resulting coupled thermal response, which can be important to determine possible failure in ‘hot spots’. In this study, a model and a solution strategy are developed to compute the response of a class of fully coupled electro‐magneto‐thermal systems composed of heterogeneous materials, involving the absorption of electromagnetic energy, its conversion to heat and changes in the electromagnetic material properties. The algorithm involves recursive staggering, whose convergence is dependent on the discretized time‐step size. The multifield system coupling can change, becoming weaker, stronger or alternating back and forth. Therefore, it is quite difficult to determine a priori the time‐step size needed to meet a prespecified tolerance on the staggering error, i.e. the incomplete resolution of the coupling between the fields. The presented solution process involves time‐step size adaptivity to control the contraction mapping constant of the multifield system operator in order to induce desired staggering rates of convergence within each time step and to control the staggering error. Three‐dimensional numerical experiments are performed to illustrate the behavior of the model and the solution strategy. Copyright © 2008 John Wiley & Sons, Ltd.
Synthesis and characterization of chiral liquid‐crystalline polysiloxanes containing fluorinated units and sulfonic acid groups
Authors: Meng Fan‐Bao , Sun Yan‐Hui , Gao Yong‐Mei , Song Xian‐Gen , Zhang Bao‐Yan
Published: April 2008

Chiral side‐chain liquid‐crystalline polysiloxanes (PS‐1, PS‐2, PS‐3, PS‐4, PS‐5, PS‐6) bearing fluorinated units and sulfonic acid groups were synthesized with poly(methylhydrogeno)siloxane, cholest‐5‐en‐3‐ol(3β)‐4‐(2‐propenyloxy)benzoate, and 3‐trifluoromethyl‐phenyl 3‐sulfo‐4‐undec‐10‐ enoyloxy‐benzoate. The effects of fluorinated units and sulfonic acid groups on characteristic of liquid‐crystalline properties were studied. PS‐1, PS‐2, and PS‐3 exhibited both smectic and cholesteric mesophases, while PS‐4, PS‐5, and PS‐6 exhibited only cholesteric mesophase. As the polymers contained more fluorinated units and sulfonic acid groups, segregation of the fluorinated segment to the surface and aggregation of hydrogen bonding should occur. Therefore, the highly ordered lamellar mesogen–siloxane matrix systems should be disturbed severely, suggesting that PS‐4, PS‐5, and PS‐6 show no smectic phase. The maximum reflection bands become broad and shifted slightly to long wavelength from PS‐1 to PS‐6. Copyright © 2008 John Wiley & Sons, Ltd.
Chitosan‐induced synthesis of magnetite nanoparticles via iron ions assembly
Authors: Wang Yongliang , Li Baoqiang , Zhou Yu , Jia Dechang
Published: April 2008

Superparamagnetic magnetite nanoparticles were synthesized induced by chitosan hydrogel under ambient conditions via iron ions assembly, and the inducing effect of chitosan hydrogel was discussed. Results of X‐ray diffraction and transmission electron microscopy indicate that the nanoparticles were inverse cubic spinel structure magnetite with diameter about 16 nm, and the superparamagnetic nanoparticles with narrow size distribution dispersed uniformly in chitosan. The magnetization measurements indicated that the nanoparticles showed the typical superparamagnetic behavior. The crystallinity, morphology, and magnetic properties of magnetite nanoparticles were remarkably influenced by the pH values of iron ion solutions. The interaction between magnetite and chitosan was illustrated by FT‐IR and thermogravimetric analysis, which concluded that the magnetite nanoparticles were coated by a chitosan layer via the amino groups of chitosan. The chitosan hydrogel assisted in the synthesis of superparamagnetic magnetite nanoparticles through chelation by amino groups. Copyright © 2008 John Wiley & Sons, Ltd.
Simultaneous determination of ten active components in traditional Chinese medicinal products containing both Gegen (Pueraria lobata) and Danshen (Salvia miltiorrhiza) by high‐performance liquid chromatography
Authors: Chang Qi , Sun Lan , Zhao Run‐Huai , Chow Moses S. S. , Zuo Zhong
Published: April 2008

In order to facilitate the quality control of Traditional Chinese Medicine (TCM) products containing both Gegen (Pueraria lobata) and Danshen (Salvia miltiorrhiza), a new and simple HPLC method for the simultaneous determination of 10 active components in these products has been developed. The chromatographic separation was carried out on a C18 column eluted with a mobile phase consisting of 0.1% acetic acid in water and 0.1% acetic acid in acetonitrile with gradient elution. The eluent was monitored by a photodiode array UV detector at a wavelength of 250 nm for Gegen components including puerarin, daidzein 8‐C‐apiosyl‐glucoside, daidzin and daidzein, and at 270 nm for Danshen components including danshensu, protocatechuic aldehyde, salvianolic acid B, cryptotanshinone, tanshinone I and tanshinone IIa. Excellent chromatographic separation was achieved for all studied compounds with good linearity (r2 > 0.999) over the studied concentration ranges. The developed method has been applied to the simultaneous determination of the 10 studied compounds in commercially available products containing both Gegen and Danshen. The TCM product samples were extracted by sonication with a mixture of methanol:water (80:20) containing 0.5% acetic acid. Extraction recoveries for all studied compounds were in the range of 96.01–106.18%. The intra‐day and inter‐day variations were less than 7.25 and 5.44%, respectively, for all studied compounds. The developed method has not only proved to be effective in the simultaneous determination of the 10 components, but also provides a convenient quality control approach for TCM products containing both Gegen and Danshen. Copyright © 2008 John Wiley & Sons, Ltd.
Separation and measurement of plant alkaloid enantiomers by RP‐HPLC analysis of their Fmoc‐Alanine analogs
Authors: Lee Stephen T. , Gardner Dale R. , Tom Chang Cheng‐Wei , Panter Kip E. , Molyneux Russell J.
Published: April 2008

Introduction. Ammodendrine (1), anabasine (2) and coniine (3) can cause congenital malformations in livestock. They appear naturally in both enantiomeric forms, and can cause variable physiological responses. A method to measure the enantiomeric ratio of these natural toxins is needed.

Objective. To develop a simple and economical method in order to determine the enantiomeric ratios of piperidine and pyrrolidine alkaloids in small samples of plant material.

Methodology. Mixtures of isolated or purified plant alkaloids were converted to their Fmoc‐l‐Ala‐alkaloid analogues forming diastereomeric mixtures, which were then analysed by high pressure liquid chromatography (HPLC) with mass spectrometry (MS) and ultraviolet (UV) detection to determine enantiomeric ratios.

Results. The diastereomeric analogs for ammodendrine, anabasine and nornicotine could be separated and the enantiomeric ratios determined. The Fmoc‐l‐Ala‐coniine analogue was not resolved under the HPLC conditions studied. The enantiomeric ratios of the selected plant alkaloids were measured and found to differ between both location within a species and location between species.

Conclusion. A low‐cost HPLC method to analyse the enantiomeric ratio of plant alkaloids containing primary or secondary amine nitrogens via conversion to their respective diastereomeric analogues has been developed. Published in 2008 by John Wiley & Sons.
Simulation of losses in thin‐film silicon modules for different configurations and front contacts
Authors: Brecl Kristijan , Topič Marko
Published: April 2008

A simulation tool for the quantification of electrical losses in thin‐film modules using a one‐ and two‐dimensional electrical PSpice model is presented. Two main sources of electrical losses are examined: monolithic contacts (MC) and front contacts made of a transparent conductive oxide (TCO) layer with or without a metal finger grid. Our study was focussed on amorphous and micromorph silicon modules in substrate or superstrate configuration. Results show that front contact losses (TCO losses and finger losses) prevail. While, under assumption that their subcell performances are the same, performance of amorphous silicon (a‐Si) modules do not depend on the configuration, the superstrate micromorph silicon module has a relatively slight (below 2%) advantage over the substrate counterpart due to lower electrical losses in the MC. Losses of the front contact made of a thick TCO layer or of thin TCO layer and metal finger grid on top were studied for both modules in substrate configuration and optimisation results are presented. Use of thin TCO layer and optimised finger grid and solar cell geometry is competitive and these modules can even outperform the optimised amorphous or micromorph silicon module with thick TCO front contact. In all optimised cases under standard test conditions, total relative losses can be minimised to around 10%. Copyright © 2008 John Wiley & Sons, Ltd.
Fabrication of poly(aniline‐co‐pyrrole) hollow nanospheres with Triton X‐100 micelles as templates
Authors: Zhou Chuanqiang , Han Jie , Song Genping , Guo Rong
Published: April 2008

A one‐step route has been reported for the fabrication of poly(aniline‐co‐pyrrole) (PACP) copolymer hollow nanospheres via the oxidation polymerization of a mixture of aniline and pyrrole in the presence of Triton X‐100. It was found that the variations in polymerization conditions, such as the concentrations of Triton X‐100 and comonomers, and [pyrrole]/[aniline] molar ratios, could change the size and uniformity of copolymer hollow nanospheres. The result of DLS has attested the presence of the spherical Triton X‐100 micelles swelled by the comonomers in reaction system, and such micelles might play template for the formation of hollow nanospheres, followed by developing a possible formation mechanism. The chemical structures and crystallinity of products were characterized by FTIR, UV–visible, 1H NMR spectra, and XRD patterns, respectively, to prove the copolymer chemical structures of hollow nanospheres. The thermal‐stability and solubility of PACP were improved compared with homopolymers (polyaniline and pyrrole). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3563–3572, 2008
Carbohydrate‐based amphiphilic diblock copolymers: Synthesis, characterization, and aqueous properties
Authors: Suriano Fabian , Coulembier Olivier , Degée Philippe , Dubois Philippe
Published: April 2008

Amphiphilic poly(ε‐caprolactone)‐b‐poly[(methacrylate‐graft‐poly(ethylene oxide))‐co‐6‐O‐methacryloyl‐D‐galactopyranose] (PCL‐b‐P(MAPEO‐co‐GaMa)) with various compositions and molecular weights were synthesized via a controlled four‐step strategy. The first step involves the synthesis of functionalized poly(ε‐caprolactone) macroinitiator by ring‐opening polymerization (ROP) of ε‐caprolactone (CL) as initiated by aluminum triisopropoxide (Al(OiPr)3). After selective bromination of the hydroxyl end‐group of the resulting α‐isopropoxy, ω‐hydroxy poly(ε‐caprolactone) by using 2‐bromoisobutyryl bromide, the controlled radical copolymerization of α‐methoxy, ω‐methacrylate poly(ethylene oxide) (MAPEO) with 6‐O‐methacryloyl‐1,2;3,4‐di‐O‐isopropylidene‐D‐galactopyranose (DIGaMa) was performed by atom transfer radical polymerization (ATRP) in THF at 60 °C using CuBr ligated with 1,1,4,7,10,10 hexamethyltriethylenetetramine (HMTETA) as catalytic complex. In the final step, isopropylidene protective functions were selectively removed using an aqueous formic acid solution leading to the expected amphiphilic graft copolymers. The molecular characterization of those copolymers was performed by 1H NMR spectroscopy and gel permeation chromatography (GPC) analysis. The self‐assembly of the copolymers into micellar aggregates as well as the related critical micellization concentration (CMC) in aqueous media were determined by dynamic light scattering (DLS) and fluorescence spectroscopy, respectively. In parallel, the morphology of the solid deposits of micellar aggregates was examined with atomic force microscopy (AFM). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3662–3672, 2008
Thermally latent reaction of hemiacetal ester with epoxide catalyzed by recyclable polymeric catalyst consisting of salen‐zinc complex and polyurethane main chain
Authors: Komatsu Hiroyuki , Ochiai Bungo , Endo Takeshi
Published: April 2008

This article describes the synthesis of and catalysis with a polymeric catalyst (Zn/1NHCOO) carrying salen‐zinc complex structure in the main chain prepared from polyaddition of zinc/bis(4‐hydroxy)salicylidene‐1,2‐diiminoethane and 4,4′‐diphenylmethane diisocyanate. Poly(Zn/1NHCOO) promoted the reaction of glycidyl phenyl ether (2) with 1‐propoxyethyl‐2‐ethylhexanoate (3) only at moderately elevated temperatures. Poly(Zn/1NHCOO) can be recycled by simple filtration from the reaction mixtures, and the recycled polymer is as active as the freshly prepared one. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3673–3681, 2008
Thermally latent synthesis of networked polymers from multifunctional hemiacetal ester and diepoxide catalyzed by Schiff‐base‐zinc chloride complex
Authors: Komatsu Hiroyuki , Ochiai Bungo , Endo Takeshi
Published: April 2008

Thermally latent reaction of a copolymer (P1) bearing hemiacetal ester and n‐butyl methacrylate moieties and glycidyl phenyl ether (2) was catalyzed by bis(p‐methoxybenzylidene)‐1,2‐diiminoethane/zinc chloride complex (ZnCl2/3) at 30–150 °C for 6 h. No reaction of P1 and 2 took place below 70 °C, and it smoothly proceeded above 120 °C. The latencies and activities mean that ZnCl2/3 meets both the high latencies at ambient conditions and the high activities at desired temperatures. Thermal crosslinking reaction employing multifunctional derivatives was carried out using ZnCl2/3 at 140 °C for 6 h to afford a networked polymer in high yields. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3682–3689, 2008
Homogeneous anionic PPE hybrids with silica gel
Authors: Kokado Kenta , Chujo Yoshiki
Published: April 2008

Anionic poly(p‐phenylene‐ethynylene) (PPE) incorporated polymer hybrids were synthesized from the PPE and tetramethoxysilane together with the organic polymers such as poly(vinylpyrrolidone) via a sol–gel method. Up to 10 wt % of the anionic PPE could be dispersed homogeneously in the resulting polymer hybrid matrix. The obtained polymer hybrids exhibited controllable photoluminescence properties by the modification of the internal environment of organic–inorganic polymer hybrids by changing the organic/inorganic ratios. The photoluminescence of the anionic PPE surrounded by the polymer hybrid matrix was reinforced against the thermal irradiation. Moreover, the photoluminescence of the obtained organic–inorganic polymer hybrids was also tuned by utilizing ionic interactions between the anionic PPE and the inorganic matrix. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3749–3755, 2008
Photopolymerization kinetics of tributylmethylammonium‐based (meth)acrylate ionic liquids and the effect of water
Authors: Zhou Hui , Jiménez Zulma , Pojman John A. , Paley Mark S. , Hoyle Charles E.
Published: April 2008

Polymerizable ionic liquids were synthesized from the neutralization reaction between tributylmethylammonium hydroxide and methacrylic or acrylic acid, and their photopolymerization kinetics have been determined. The acrylate monomer polymerization rate exhibited a profound dependence on the water content as follows: the monomer viscosity was a strong function of the water content, increasing substantially as the water content increased from less than 5 to 30%. For the tributylmethylammonium acrylate with less than 5% water, the viscosity was 2000 times greater than that of butyl acrylate. The high viscosity is proposed to reduce both the propagation and termination steps. Both monomers exhibited an increase in rate with temperature. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3766–3773, 2008
Synthesis and characterization of polycyanurate/montmorillonite nanocomposites
Authors: Anthoulis George I. , Kontou Evagelia , Fainleib Alexander , Bei Irina , Gomza Yurii
Published: April 2008

The advantages of cyanate esters (CEs) versus competitor systems such as epoxies and polyimides, as well as the great reinforcing potential of organoclays properly dispersed into a polymeric matrix, have been examined in a series of polycyanurate (PCN)/montmorillonite (MMT) nanocomposites prepared under appropriate polymerization conditions. The curing schedule applied resulted in gradual propagation of polymerization. Through this procedure, the intragallery curing rate becomes comparable to the extragallery one, allowing intercalation before gelation. Systems with clay loadings from 1 to 3% per weight were synthesized, and their morphology and mechanical properties were studied by means of scanning electron microscopy (SEM), atomic force microscopy (AFM), wide angle X‐ray scattering (WAXS), dynamic mechanical analysis (DMA), and tensile tests. Microscopy investigations revealed better dispersion for the 3 wt % system compared to smaller concentrations, in which aggregation and, in some cases, agglomeration were the conspicuous features. Roughness and area analyses revealed more homogeneous dispersion for this nanocomposite. Topology and 3D‐phase images further suggested considerable reduction of the average particle diameters. WAXS analysis showed that the interlayer spacing of nanocomposites was increased compared to pristine MMT, indicating the formation of intercalated structures. On the other hand, tensile strength and elongation at break values displayed abrupt diminution with MMT addition, while Young's modulus exhibited a slight but systematic increment with MMT content. The decreasing glass transition tendency observed for small clay loadings was reversed in the case of 3 wt %, while secondary transitions were practically unaffected by the presence of MMT. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1036–1049, 2008
Filler size effects on the conductivity of polymer nanocomposites: Semiconductive phthalocyanine nanoparticles in epoxy matrices
Authors: Yuan Ming , Brokken‐Zijp José C. M. , Huijbregts Laura J. , De With Gijsbertus
Published: April 2008

Three Cobalt(III) phthalocyanine (Phthalcon) powders with different particle sizes and chemical compositions, but almost equal XRD spectra and powder conductivity were synthesized and used as conductive fillers in crosslinked epoxy matrices. Two of these Phthalcons are new compounds. The relation between the conductivity of the composites and the type and amount of filler used was determined. The influence of particle size and chemical composition on this relation appeared to be minimal. These composites had a percolation threshold of 0.9 vol % and a maximum volume conductivity of 10−7 S/cm. Detailed analysis showed that the particle networks have very similar fractal structures and that they are likely to be formed by diffusion limited cluster‐cluster aggregation during processing. Evidence is presented that these particle networks are formed at an early stage of crosslinking and that the charge transfer between particles in the networks is neither limited by the Phthalcon particle size, nor by the presence of polymer matrix between the particles. The maximum volume conductivity of these composites is likely to be limited by the amount of filler used, the crystal structure defects on the particle surface, and the fractality and the imperfection of the particle networks. The impact of these findings on the conductivity of other polymer nanocomposites is discussed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1079–1093, 2008
Predicting functional residues inPlasmodium falciparumplasmepsins by combining sequence and structural analysis with molecular dynamics simulations
Authors: Valiente Pedro A. , Batista Paulo R. , Pupo Amaury , Pons Tirso , Valencia Alfonso , Pascutti Pedro G.
Published: April 2008

Plasmepsins are aspartic proteases involved in the initial steps of the hemoglobin degradation pathway, a critical stage in thePlasmodium falciparumlife cycle during human infection. Thus, they are attractive targets for novel therapeutic compounds to treat malaria, which remains one of the world's biggest health problems. The three‐dimensional structures available forP. falciparumplasmepsins II and IV make structure‐based drug design of antimalarial compounds that focus on inhibiting plasmepsins possible. However, the structural flexibility of the plasmepsin active site cavity combined with insufficient knowledge of the functional residues and of those determining the specificity of parasitic enzymes is a drawback when designing specific inhibitors. In this study, we have combined a sequence and structural analysis with molecular dynamics simulations to predict the functional residues inP. falciparumplasmepsins. The careful analysis of X‐ray structures and 3D models carried out here suggests that residues Y17, V105, T108, L191, L242, Q275, and T298 are important for plasmepsin function. These seven amino acids are conserved across the malarial strains but not in human aspartic proteases. Residues V105 and T108 are localized in a flap of an interior pocket and they only establish contacts with a specific non‐peptide achiral inhibitor. We also observed a rapid conformational change in the L3 region of plasmepsins that closes the active site of the enzyme, which explains earlier experimental findings. These results shed light on the role of V105 and T108 residues in plasmepsin specificities, and they should be useful in structure‐based design of novel, selective inhibitors that may serve as antimalarial drugs. Proteins 2008. © 2008 Wiley‐Liss, Inc.
Rosacea: a symptom‐based approach to management
Authors: Seaton Edward
Published: April 2008

Rosacea is a common skin condition of unknown aetiology. Dr Seaton describes the recommended management of the vascular and inflammatory symptoms. Copyright © 2008 Wiley Interface Ltd
Development and evaluation of active packaging for sliced mozzarella preservation
Authors: dos Santos Pires Ana Clarissa , de Fátima Ferreira Soares Nilda , de Andrade Nélio José , da Silva Luís Henrique Mendes , Camilloto Geany Peruch , Bernardes Patrícia Campos
Published: April 2008

Antimicrobial films were formed by the incorporation of nisin (NI), natamycin (NA) and a combination of both (NI + NA) into cellulose polymer. Film efficacies were evaluated in vitro against Staphylococcus aureus ATCC 6538, Listeria monocytogenes ATCC 15313, Penicillium sp. and Geotrichum sp. The films were also evaluated on sliced mozzarella cheese against moulds and yeasts, Staphylococcus sp. and psychrotrophic bacteria. Mechanical and microscopic properties of the films and the diffusion of the antimicrobial agents from the film to the cheese were also evaluated. Films containing NI showed an antimicrobial effect in vitro against S. aureus and L. monocytogenes, while films containing NA were effective in vitro against Penicillium sp. and Geotrichum sp. By the ninth day of storage at 12 ± 2°C, the count of yeasts and moulds on cheese covered with films containing NA decreased 2 log10 units compared with the count on cheese with control films. NI film did not show an effect against Staphylococcus sp., but it was effective against psychrotrophic bacteria for 6 days of storage of the cheese. The incorporation of antimicrobial compounds decreased the resistance and elongation of the films and caused changes in their molecular conformation. NI diffusion from the films to the cheese was not detected; however, time‐dependent diffusion of NA from the film containing NI + NA was measured. The incorporation of NI and NA together in the films did not show an effect. The film containing NA showed potential for application as active food packaging for sliced mozzarella cheese. Copyright © 2008 John Wiley & Sons, Ltd.
Diffusion technique for 15N and inorganic N analysis of low‐N aqueous solutions and Kjeldahl digests
Authors: Chen Rui Rui , Dittert Klaus
Published: April 2008

Diffusion of ammonia is a common sample preparation method for the stable isotope analysis of inorganic nitrogen in aqueous solution. Classical diffusion methods usually require 6–12 days of diffusion and often focus on 15N/14N analysis only. More recent studies have discussed whether complete N recovery was necessary for the precise analysis of stable N isotope ratios. In this paper we present a newly revised diffusion technique that allows correct and simultaneous determination of total N and 15N at% from aqueous solutions and Kjeldahl digests, with N concentrations down to sub‐0.5‐mg N L−1 levels, and it is tested under different conditions of 15N isotope labelling. With the modification described, the diffusion time was reduced to 72 h, while the ratios of measured and expected 15N at% were greater than 99% and the simultaneous recovery of total N was >95%. Analysis of soil microbial biomass N and its 15N/14N ratio is one of the most important applications of this diffusion technique. An experiment with soil extracts spiked with 15N‐labelled yeast showed that predigestion was necessary to prevent serious N loss during Kjeldahl digestion of aqueous samples (i.e. soil extracts). The whole method of soil microbial biomass N preparation for 15N/14N analysis included chloroform fumigation, predigestion, Kjeldahl digestion and diffusion. An experiment with soil spiked with 15N‐labelled yeast was carried out to evaluate the method. Results showed a highly significant correlation of recovered and added N, with the same recovery rate (0.21) of both total N and 15N. A kN value of 0.25 was obtained based on the data. In conclusion, the diffusion method works for soil extracts and microbial biomass N determination and hence could be useful in many types of soil/water studies. Copyright © 2008 John Wiley & Sons, Ltd.