bluuebunny/crossref_metadata_2025 huggingface dataset:
Cover Picture: Asymmetric Organocatalytic Henry Reaction (Angew. Chem. Int. Ed. 6/2006)
Authors: Marcelli Tommaso , van der Haas Richard N. S. , van Maarseveen Jan H. , Hiemstra Henk
Published: January 2006

Alkaloids extracted from the Quinine tree bark are a privileged scaffold for the development of asymmetric organocatalysts. In their Communication on page 929 ff., H. Hiemstra and co‐workers describe a novel Cinchona‐derived thiourea compound able to catalyze the Henry (nitroaldol) reaction of aromatic aldehydes with high enantioselectivities. The cover picture shows Cinchona pubescens (courtesy of Forest and Kim Starr, USA) and a typical Henry product.
Adsorption of poly (4‐sodium styrene sulfonate) on kaolinite clays
Authors: Sadek O. M. , Mekhemer W. K. , Assaad F. F. , Mostafa B. A.
Published: January 2006

The adsorption of polymer on clay particles has great importance in many industrial applications. This work aimed to study the adsorption of anionic polymer, poly (4‐sodium styrene sulfonate), on kaolinite clay surfaces. Three different Egyptian kaolinite clay samples were used. The kaolinite clays were saturated with sodium or calcium cation. It was found that the Freundlich isotherm is applicable for this polymer adsorption on kaolinite. The parameters of the Freundlich equation are very close, indicating a comparable nature for the binding behavior between the different samples of kaolinite and the adsorbed polymer. The adsorption process was examined at different pH values (3, 6, and 9 ± 0.1) to cover the range below and above the point of zero charge of kaolinite surfaces. It was found that, below this point, the polymer adsorption increased, while above it the polymer adsorption decreased. The polymer adsorption on calcium kaolinite was higher than that of sodium kaolinite at the same pH value. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1712–1719, 2006
Synthesis and characterization of poly(urethane‐ester)s based on calcium salt of mono(hydroxybutyl)phthalate
Authors: Prasath R. Arun , Nanjundan S. , Pakula T. , Klapper M.
Published: January 2006

Calcium‐containing poly(urethane‐ester)s (PUEs) were prepared by reacting diisocyanate (HMDI or TDI) with a mixture of calcium salt of mono(hydroxybutyl)phthalate [Ca(HBP)2] and hydroxyl‐terminated poly(1,4‐butylene glutarate) [HTPBG1000], using di‐n‐butyltin‐dilaurate as catalyst. About six calcium‐containing PUEs having different composition were synthesized by taking the mole ratio of Ca(HBP)2:HTPBG1000:diisocyanate (HMDI or TDI) as 3:1:4, 2:2:4, and 1:3:4. Two blank PUEs were synthesized by the reaction of HTPBG1000 with diisocyanate (HMDI or TDI). The polymers were characterized by IR, 1H NMR, Solid state 13C‐CP‐MAS NMR, TGA, DSC, XRD, solubility, and viscosity studies. The Tg value of PUEs increases with increase in the calcium content and decreases with increase in soft segment content. The viscosity of the calcium‐containing PUEs increases with increase in the soft segment content and decreases with increase in the calcium content. X‐ray diffraction patterns of the polymers show that the HMDI‐based polymers are partially crystalline and TDI‐based polymers are amorphous in nature. The dynamic mechanical analysis of the calcium‐containing PUEs based on HMDI shows that with increase in the calcium content of polymer, modulus (g′ and g″) increases at any given temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1720–1727, 2006
Phase diagrams of blends of poly(phenylene ether), polystyrene, and diglycidyl ether of bisphenol A: Influence of the molar mass of poly(phenylene ether)
Authors: Soulé E. R. , Fine T. , Borrajo J. , Williams R. J. J. , Pascault J. P.
Published: January 2006

Phase diagrams of ternary blends of poly(phenylene ether) (PPE, Mn = 1.2 and 12 kg mol−1), polystyrene (PS, Mn = 22.5 kg mol−1), and diglycidyl ether of bisphenol A (DGEBA) were experimentally obtained in an extended range of temperatures and fitted with the Flory–Huggins model using three binary interaction parameters. A significant increase in miscibility together with the appearance of an immiscibility loop was found for PPEs with Mn values comprised in the range between 1 and 10 kg mol−1. This enables us to obtain initial homogeneous solutions in regions of high DGEBA concentrations, a possibility that was not previously reported for this ternary blend. This opens new possibilities for the toughening of epoxies replacing a single thermoplastic with a thermoplastic blend where both components (PS and PPE) are completely miscible. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1742–1747, 2006
Isothermal and nonisothermal cure kinetics of an epoxy/poly(oxypropylene)diamine/octadecylammonium modified montmorillonite system
Authors: Brnardic Ivan , Ivankovic Marica , Ivankovic Hrvoje , Mencer Helena Jasna
Published: January 2006

The effect of an octadecylammonium‐exchanged montmorillonite on the curing kinetics of a thermoset system based on a bisphenol A epoxy resin and a poly(oxypropylene)diamine curing agent were studied with differential scanning calorimetry (DSC) in isothermal and dynamic (constant‐heating‐rate) conditions. Montmorillonite and the prepared composites were characterized by X‐ray diffraction analysis and simultaneous DSC and thermogravimetric analysis. The analysis of the DSC data indicated that the intercalated octadecylammonium cations catalyzed the epoxy–amine polymerization. A kinetic model, arising from an autocatalyzed reaction mechanism, was applied to the DSC data. Fairly good agreement between the experimental data and the modeling data was obtained. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1765–1771, 2006
Electronic Interactions in a New π‐Extended Tetrathiafulvalene Dimer
Authors: Díaz Marta C. , Illescas Beatriz M. , Martín Nazario , Perepichka Igor F. , Bryce Martin R. , Levillain Eric , Viruela Rafael , Ortí Enrique
Published: January 2006

The first π‐extended tetrathiafulvalene (exTTF) dimer in which the two exTTF units are covalently connected by 1,3‐dithiole rings has been obtained in a multistep synthetic procedure involving the Ullmann cross‐coupling reaction by using copper(I) thiophene‐2‐carboxylate (CuTC). The electronic spectrum reveals a significant electronic interaction between the exTTF units. The electrochemical study carried out by cyclic voltammetry in solution and in thin‐layer conditions, and the electrochemical simulation and spectroelectrochemical (SEC) measurements confirm the electronic communication and show that the oxidation of dimer 14 occurs as two consecutive 2 e− processes D0–D0→D2+–D0→D2+–D2+. Theoretical calculations, performed at the B3P86/6‐31G* level, confirm the experimental findings and predict that 142+ exists as a delocalized D.+–D.+ species in the gas phase and as a localized D2+–D0 species in solution (CH3CN or CH2Cl2). Oxidation of 142+ forms the tetracation 144+ which is constituted by two aromatic anthracene units bearing four aromatic, almost orthogonal 1,3‐dithiolium cations.
Cover Picture: Controlled Self‐Assembly of Amphiphilic Oligopeptides into Shape‐Specific Nanoarchitectures (Chem. Eur. J. 5/2006)
Authors: Koga Tomoyuki , Higuchi Masahiro , Kinoshita Takatoshi , Higashi Nobuyuki
Published: January 2006

Fine tuning of peptide sequence, reaction time, and solution pH enabled the construction of novel three‐dimensional nanoarchitectures by controlled self‐assembly of peptide building blocks (shown in the cover picture). Several self‐assembled structures, such as β‐sheet plates, β‐sheet fibers, α‐helix particles, and α‐helix plates, were fabricated on the nanometer scale, and their conformation and self‐assembling mechanisms studied. As suggested by N. Higashi et al. on page 1360 ff., this controlled self‐assembly should elucidate the mechanism of peptide aggregation, and be useful in the design of novel biorelated nanomaterials.
Clinicopathological characteristics of colorectal cancers with loss of imprinting of insulin‐like growth factor 2
Authors: Sasaki Jun‐ichi , Konishi Fumio , Kawamura Yutaka J. , Kai Toshihiro , Takata Osamu , Tsukamoto Toshihiko
Published: January 2006

Loss of imprinting (LOI), the biallelic expression of an imprinting gene, of insulin‐like growth factor 2 (IGF2) has been reported to be associated with colorectal carcinogenesis because of its high prevalence in normal colorectal mucosa as well as cancerous tissue in patients with colorectal cancer. However, the characteristics of colorectal cancer associated with IGF2 LOI have not been clearly demonstrated. In this study, we investigated the IGF2 LOI status of tumor and normal mucosa in 255 consecutive patients with colorectal cancer. Of these, 95 were informative for IGF2 LOI, by direct sequencing of mRNA of IGF2. Regarding the LOI status in each patient, the prevalence of LOI in nontumorus normal mucosa was significantly higher in cases with LOI‐positive cancer than in those with LOI‐negative cancer (p < 0.001). Concerning the clinicopathological characteristics of LOI‐positive cancer, the prevalence of poorly differentiated or mucinous carcinoma (p = 0.016) and of right‐sided locations (p = 0.009) were significantly higher than those of LOI‐negative cancer. Contrary to past reports that revealed a significant correlation between microsatellite instability (MSI) and IGF2 LOI in a relatively small series of noncohort patients, our study did not find a statistically significant difference in LOI‐positive rate between MSI‐positive and ‐negative cases. Our results suggested the presence of a particular type of colorectal cancer associated with the proximal colon and poor differentiation, but independent of MSI. These results may contribute to clarification of the mechanism of colorectal tumorigenesis and to determining an appropriate screening strategy for colorectal carcinoma. © 2006 Wiley‐Liss, Inc.
A p21/WAF1 mutation favors the appearance of drug resistance to paclitaxel in human noncancerous epithelial mammary cells
Authors: Galmarini Carlos María , Bouchet Benjamin Pierre , Audoynaud Carole , Lamblot Christelle , Falette Nicole , Bertholon Jacques , Wang Qing , Beghin Anne , Dumontet Charles , Puisieux Alain
Published: January 2006

We investigated the mechanisms responsible for paclitaxel resistance in HME‐1 cells (human mammary epithelial cells immortalized with hTERT). These cells were exposed to paclitaxel (10 pM for 7 days) and 20 cellular surviving populations (PSP) were obtained. PSP demonstrated high levels of resistance to paclitaxel cytotoxicity as compared with HME‐1 cells. Activation of mdr‐1 gene expression was observed in 2 PSP. Protein expression analysis using a C‐terminal targeted antibody showed that 13 PSP were negative for p21/WAF1 expression after ionizing radiation (6 Gy) or doxorubicin (100 nM) treatment. Sequencing of the 3 exons of the CDKN1A gene revealed that 13 PSP contained a point mutation in exon 2. This mutation consisted in a T insertion at codon 104 leading to a premature STOP codon appearance. Mismatch amplification mutation assay and RFLP‐PCR confirmed the presence of the mutation in 16 PSP. Western blot using an N‐terminal targeted antibody demonstrated that the C‐terminal‐truncated p21/WAF1 protein (14 kDa) was indeed expressed in the 13 PSP. Our data suggest that p21/WAF1 inactivation may confer a strong resistance to paclitaxel in noncancerous breast epithelial cells harboring a p21/WAF1 mutant. © 2006 Wiley‐Liss, Inc.
Obtaining smoking histories for population‐based studies on multiple primary cancers: Connecticut, 2002
Authors: Polednak Anthony P.
Published: January 2006

Because of the absence of data on smoking history for patients in cancer registries, large population‐based studies have been unable to directly assess the role of smoking in the risk of multiple primary cancers. In a random sample of 618 adults diagnosed with invasive cancer in 2002 and reported to the population‐based Connecticut (CT) cancer registry, however, search of hospital records identified smoking history (current, former, never‐ or nonsmoker) for 83.3%. Number of cigarettes per day was known for 71.3% of 289 current or former smokers, while duration of quitting was found for 92.3% of 194 former smokers. Smoking status was strongly associated with current heavy alcohol use. Hospital records appear to be a promising resource for population‐based studies on smoking histories in relation to risk of multiple primaries, although completeness of information needs to be improved in CT and assessments are needed in other cancer registries. © 2006 Wiley‐Liss, Inc.
Real‐Time Analysis of Enzymatic Surface‐Initiated Polymerization Using Surface Plasmon Resonance (SPR)
Authors: Kim Young‐Rok , Paik Hyun‐jong , Ober Christopher K. , Coates Geoffrey W. , Mark Sonny S. , Ryan Thomas E. , Batt Carl A.
Published: January 2006

Summary: The kinetics of enzymatic surface‐initiated polymerization of PHB on gold surface has been examined by SPR and the resultant polymer layers characterized by AFM and FT‐IR spectrometry. The immobilized enzyme catalyzed surface‐initiated polymerization of 3HB‐CoA, resulting in the formation of a polymer brush on the surface. The rate of polymer growth from the surface was monitored by SPR in real‐time. Polymer growth as measured by the increase in the resonance angle showed no apparent lag phase during the polymerization reaction. SPR analysis also revealed that the thickness of the polymer film could be controlled by varying the initial enzyme density on the surface. The average thicknesses of the PHB film after polymerization reaction were 95, 45 and 15 nm for the surfaces that were treated with 0.5, 0.3 and 0.1*10−6 M of enzyme, respectively.

The binding of PHA synthase at different concentration to the mixed SAMs and subsequent polymerization.

magnified image

The binding of PHA synthase at different concentration to the mixed SAMs and subsequent polymerization.
Global attractor for heat convection problem in a micropolar fluid
Authors: Tarasińska Agnieszka
Published: January 2006

The article is devoted to describe asymptotics in the heat convection problem for a micropolar fluid in two dimensions. We show the existence and the uniqueness of global in time solutions and then prove the existence of a global attractor for considered model. Next, the Hausdorff dimension of the global attractor is estimated. Copyright © 2006 John Wiley & Sons, Ltd.
Analysis of a novel preconditioner for a class of p‐level lower rank extracted systems
Authors: Salapaka S. , Peirce A.
Published: January 2006

This paper proposes and studies the performance of a preconditioner suitable for solving a class of symmetric positive definite systems, Âx=b, which we call p‐level lower rank extracted systems (p‐level LRES), by the preconditioned conjugate gradient method. The study of these systems is motivated by the numerical approximation of integral equations with convolution kernels defined on arbitrary p‐dimensional domains. This is in contrast to p‐level Toeplitz systems which only apply to rectangular domains. The coefficient matrix, Â, is a principal submatrix of a p‐level Toeplitz matrix, A, and the preconditioner for the preconditioned conjugate gradient algorithm is provided in terms of the inverse of a p‐level circulant matrix constructed from the elements of A. The preconditioner is shown to yield clustering in the spectrum of the preconditioned matrix which leads to a substantial reduction in the computational cost of solving LRE systems. Copyright © 2006 John Wiley & Sons, Ltd.
Poly(amide imide)s and poly(amide imide) composite membranes by interfacial polymerization
Authors: Buch Premang R , Mohan D Jagan , Reddy Alamuru VR
Published: January 2006

Novel amic acid diamines (AADs) (2‐carboxyterephthalamido‐bis(alkyl or aryl amine)s, H2NXNH(O)CC6H3(COOH)C(O)NHXNH2, where X is
magnified image were synthesized by reacting trimellitic anhydride chloride with aromatic or aliphatic diamines in dimethylformamide at 5–10 °C. Poly(amide imide)s (PAIs) with an amide to imide ratio of three in the polymer chains were prepared by interfacial polycondensation of the AADs in aqueous alkaline solution with isophthaloyl chloride or terephthaloyl chloride in dichloromethane at ambient temperature to form poly(amide amic acid)s, followed by their subsequent thermal cycloimidization. All of the PAIs were soluble in polar aprotic solvents such as dimethylformamide, dimethylacetamide, dimethyl sulfoxide and N‐methylpyrrolidone, and have inherent viscosities in the range 0.15–0.48 dL g−1. The polymers were characterized by IR and NMR spectroscopy, TGA and DSC techniques. The PAIs have initial decomposition temperatures in the range 250–460 °C in air, and glass transition temperatures of 128–320 °C, depending upon the structures of the monomers. Composite membranes containing a poly(amide amic acid) and poly(amide imide) barrier layer on the top of a porous polyethersulfone support were prepared by in situ interfacial polymerization of the AADs in aqueous alkaline solution with trimesoyl chloride in hexane, and subsequent curing. The performances of these membranes were evaluated by using aqueous feed solutions containing 2000 ppm NaCl, Na2SO4 or CaCl2. Copyright © 2006 Society of Chemical Industry
Introduction of unusual properties into polymers by the use of liquid‐crystalline moieties
Authors: Palaprat G , Weyland M , Phou T , Binet C , Marty JD , Mingotaud AF , Mauzac M
Published: January 2006

The introduction of mesogenic substituents on polymer backbones facilitates the formation of materials with anisotropic properties. At the same time the polymer chains are connected each other through these substituents in a transient network. The properties of the polymer material, such as the mechanical response or conductivity, are modified by the presence of the liquid‐crystalline groups and can be tuned by changing the organisation of the mesogenic groups. Crosslinking the polymer in the liquid‐crystalline state induces the manifestation of some memory effect. These phenomena were used for improving the mechanisms of recognition in molecular imprinted materials. Copyright © 2006 Society of Chemical Industry
Ring‐opening polymerization of ε‐caprolactone initiated by rare earth alkoxides and borohydrides: a comparative study
Authors: Palard Isabelle , Schappacher Michèle , Soum Alain , Guillaume Sophie M
Published: January 2006

The polymerization of ε‐caprolactone initiated by trivalent rare earth (Ln) derivatives, namely the isopropoxide ‘Ln(OiPr)3’ opposed to the borohydride Ln(BH4)3(THF)3 (Ln = La, Nd, Sm) and (Cp*)2Sm(BH4)(THF) (Cp* = (η‐C5Me5)), has been evaluated. The comparison, based on the structure of the initiator and on the polymerization features (molar mass, molar mass distribution, side reactions) reveals some differences especially in the number of active polymer chains per metal and in the occurrence of some transfer reactions with Ln(BH4)3(THF)3. Polymerizations performed with borohydride derivatives lead to a gel as a result of van der Waals interactions, while the reaction medium remains fluid with the alkoxide species. A typical coordination‐insertion mechanism with oxygen‐acyl bond cleavage of the monomer prevails with both types of initiators. However, while the alkoxide complexes lead to α,ω‐hydroxyalkoxypoly(ε‐caprolactone), the borohydride compounds allow the synthesis of α,ω‐dihydroxypoly(ε‐caprolactone). Both polymerization processes are well controlled under specific conditions. Copyright © 2006 Society of Chemical Industry
Use of a fluorescent internal protein standard to achieve quantitative two‐dimensional gel electrophoresis
Authors: Wheelock Åsa M. , Morin Dexter , Bartosiewicz Matthew , Buckpitt Alan R.
Published: January 2006

2‐DE is a powerful separation method for complex protein mixtures. However, large intergel variations in spot intensity limit its use for quantitative proteomics studies. To address this issue, we developed a fluorescent internal protein standard for use in 2‐DE analysis. Protein samples are spiked with an Alexa‐labeled internal standard (ALIS) prior to separation with 2‐DE. Due to the high extinction coefficient of the Alexa‐fluor, incorporation of 0.1% of total protein is sufficient to allow visualization of the internal standard yet low enough to avoid interference in subsequent quantification and identification steps. Following 2‐DE, total proteins are visualized with fluorescent postelectrophoretic stains spectrally separated from ALIS. Four protein stains, Deep Purple, Sulforhodamine G, ruthenium II‐tris(bathophenanthroline disulfonate) (RuTBS), and SYPRO Ruby, including improved purification and staining protocols for RuTBS and ten‐fold dilutions of SYPRO Ruby were evaluated. All staining protocols were compatible with the ALIS method and had similar LODs (1–4 ng) and dynamic ranges (103). ALIS is a powerful normalization method for quantitative 2‐DE which avoids potential problems associated with dual spot migration patterns observed in the DIGE method. Furthermore, ALIS provides significantly improved normality in the distribution of spot abundance‐variance compared to normalization through division by the total spot volume.
Proteomic and SAGE profiling of murine melanoma progression indicates the reduction of proteins responsible for ROS degradation
Authors: de Souza Gustavo A. , Godoy Lyris M. F. , Teixeira Veronica R. , Otake Andreia H. , Sabino Adão , Rosa José C. , Dinarte Anemari R. , Pinheiro Daniel G. , Silva Wilson A. , Eberlin Marcos N. , Chammas Roger , Greene Lewis J.
Published: January 2006

Using 2‐DE of total cell protein extracts, we compared soluble proteins from murine melanoma lines Tm1 and Tm5 with proteins from the nontumoral cell melan‐a from which they were derived. Seventy‐one of the 452 spots (average) detected with CBB were differentially accumulated, i.e., increased or decreased twofold. Forty‐four spots were identified by PMF/MALDI‐TOF, 15 with increased and 29 with decreased protein levels. SAGE showed that 17/34 (50%) of the differentially accumulated proteins, pI range 4–7, presented similar differences at the mRNA level. Major reductions in protein were observed in tumor cells of proteins that degrade reactive oxygen species (ROS). Decreases of ⋛ twofold in GST, superoxide dismutase, aldehyde dehydrogenase, thioredoxin, peroxiredoxin 2, and peroxiredoxin 6 protein were observed. SAGE indicated the reduction of other proteins involved in ROS degradation. As expected, the accumulation of exogenous peroxides was significantly higher in the tumor cells while the levels of glutathionylation were two times lower in the tumor cells compared to melan‐a. The differential accumulation of proteins involved in oncogene/tumor suppressor pathways was observed. Melanoma cells can favor survival pathways activated by ROS by inhibiting p53 pathways and activation of Ras and c‐myc pathways.
Human plasma proteome analysis by reversed sequence database search and molecular weight correlation based on a bacterial proteome analysis
Authors: Park Gun Wook , Kwon Kyung‐Hoon , Kim Jin Young , Lee Jeong Hwa , Yun Sung‐Ho , Kim Seung Il , Park Young Mok , Cho Sang Yun , Paik Young‐Ki , Yoo Jong Shin
Published: January 2006

In shotgun proteomics, proteins can be fractionated by 1‐D gel electrophoresis and digested into peptides, followed by liquid chromatography to separate the peptide mixture. Mass spectrometry generates hundreds of thousands of tandem mass spectra from these fractions, and proteins are identified by database searching. However, the search scores are usually not sufficient to distinguish the correct peptides. In this study, we propose a confident protein identification method for high‐throughput analysis of human proteome. To build a filtering protocol in database search, we chose Pseudomonas putida KT2440 as a reference because this bacterial proteome contains fewer modifications and is simpler than the human proteome. First, the P. putida KT2440 proteome was filtered by reversed sequence database search and correlated by the molecular weight in 1‐D‐gel band positions. The characterization protocol was then applied to determine the criteria for clustering of the human plasma proteome into three different groups. This protein filtering method, based on bacterial proteome data analysis, represents a rapid way to generate higher confidence protein list of the human proteome, which includes some of heavily modified and cleaved proteins.
Alteration of the glutamate and GABA transporters in the hippocampus of the Niemann‐Pick disease, type C mouse using proteomic analysis
Authors: Byun Kyunghee , Kim Jaewoo , Cho Sang‐Yun , Hutchinson Brian , Yang Se‐Ran , Kang Kyung‐Sun , Cho Moonjae , Hwang Kyukye , Michikawa Makoto , Jeon Young‐Wook , Paik Young‐Ki , Lee Bonghee
Published: January 2006

Niemann‐Pick disease type C (NPC) is a fatal autosomal recessive cholesterol disorder characterized by severe progressive neurodegeneration. To unveil the mechanism of neurodegeneration, proteomic and morphological approaches were applied to the hippocampus in NPC –/– mouse. Two‐DE was utilized to resolve the hippocampal protein expression profiles of 4‐ and 8‐week‐old NPC +/+ and –/– mice. Differentially expressed protein spots were identified by MALDI‐TOF MS and database searching. At 4 weeks of age, there was no significant difference in protein profiles between NPC +/+ and –/– mice. However, at the age of 8 weeks, NPC +/+ and –/– mice showed marked difference in protein expressions. Among these, glutamate receptor 2 precursor was identified. The immunohistochemical study on neurotransporters showed that glial GABA transporter (GAT‐3) increased in both 4‐ and 8‐week‐old NPC –/– mouse and glutamic acid decarboxylase (GAD‐6) increased in 8‐week‐old NPC –/– mouse. Glial glutamate transporter, excitatory amino acids carrier‐1 (EAAC1), decreased in 8‐week‐old NPC –/– mouse. In conclusion, our data may provide insight into the understanding of the basic mechanism through perturbation of protein networks and neurotransporter systems in a single gene knockout model of NPC disease.
Is protein overlap in two‐dimensional gels a serious practical problem?
Authors: Hunsucker Stephen W. , Duncan Mark W.
Published: January 2006

In a recently published article, Campostrini et al. [Proteomics 2005, 5, 2385–2395] raised questions regarding the utility of 2‐D gels in proteomics research. We believe that the authors have overlooked several key issues including the dynamic range of protein expression and the sensitivity of the analytical methods used to explore a proteome. We argue that 2‐D gels have and will continue to provide meaningful quantitative data when applied to proteomic analysis and that the practical significance of spot overlap has been overstated.
Solvent effect on the heat of solution and partial molar volume of some non‐electrolytes and lithium perchlorate
Authors: Kiselev Vladimir D. , Kashaeva Elena A. , Iskhakova Gulnara G. , Potapova Lubov N. , Konovalov Alexander I.
Published: January 2006

For several non‐electrolytes and for lithium perchlorate the solvent effect on the heat of solution and partial molar volumes was studied. In the absence of the donor–acceptor and electrostatic interactions, clear proportionality can be seen only in the alkane solutions and these changes are defined by the non‐alkane component. For solutions of π‐acceptor (tetracyanoethylene) and ν‐acceptor (gallium chloride) in the presence of π,π‐, π,ν‐ and n,ν‐complexes, the relation between the changes of interaction energy and the values of the partial molar volumes can be seen. The maximum change in the value of partial molar volumes (up to 50 cm3 mol−1) was noted for lithium perchlorate in ten solvents. The volume change is proportional to the compressibility coefficients of the solvents and correlates less with the values of heat of solution and solvent permittivity. Copyright © 2006 John Wiley & Sons, Ltd.
Characterization of poly[(R)‐3‐hydroxybutyrate‐co‐ε‐caprolactone] copolymers by matrix‐assisted laser desorption/ionization time‐of‐flight and electrospray ionization mass spectrometry
Authors: Alicata Rossana , Barbuzzi Tony , Giuffrida Mario , Ballistreri Alberto
Published: January 2006

Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS) of narrowly dispersed molecular weight gel permeation chromatography (GPC) fractions was used to characterize random and microblock poly[(R)‐3‐hydroxybutyrate‐co‐ε‐caprolactone] [P(HB‐co‐CL)] copolymers obtained via the acid‐catalyzed transesterification of the corresponding homopolymers, poly([(R)‐3‐hydroxybutyrate] (PHB) and poly(ε‐caprolactone) (PCL). High‐quality mass spectra were obtained, which made it possible to establish the nature of the polymer end groups. Besides the carboxylic termination, two other moieties were found: alcoholic and tosyl end groups. MALDI mass spectra of CL‐rich samples possessed mostly tosyl end groups, while HB‐rich samples possessed mostly alcoholic end groups, showing that the tosyl moiety is linked prevalently to CL terminal units. The higher resolution of electrospray ionization (ESI) mass spectra of lower molecular weight GPC fractions permitted the identification of the different oligomer species hypothesized in the assignment of the corresponding MALDI mass spectra. Partial methanolysis of these copolymers was explored as a method of producing mixed HB‐CL oligomers to be utilized as new synthons, possessing a minor number of chiral centers from those obtained from hydrolysis of biotechnologically synthesized poly(hydroxyalkanoates) (PHAs). Copyright © 2006 John Wiley & Sons, Ltd.
Mild cognitive impairment: applicability of research criteria in a memory clinic and characterization of cognitive profile
Authors: ALLADI SUVARNA , ARNOLD ROBERT , MITCHELL JOANNA , NESTOR PETER J. , HODGES JOHN R.
Published: January 2006

Background. We explored the applicability of recently proposed research criteria for mild cognitive impairment (MCI) in a memory clinic and changes in case definition related to which memory tests are used and the status of general cognitive function in MCI.

Method. A total of 166 consecutive GP referrals to the Cambridge Memory Clinic underwent comprehensive neuropsychological and psychiatric evaluation.

Results. Of 166 cases, 42 were excluded (significant depression 8, established dementia 29 and other disorders 5). Of 124 non-demented, non-depressed patients, 72 fulfilled Petersen's criteria for amnestic MCI based upon verbal memory performance [the Rey Auditory Verbal Learning Test (RAVLT)] and 90 met criteria if performance on verbal and/or non-verbal memory tests [the Rey figure recall or the Paired Associates Learning test (PAL)] was considered. Of the 90 broadly defined MCI cases, only 25 had pure amnesia: other subtle semantic and/or attention deficits were typically present. A further 12 were classed as non-amnestic MCI and 22 as ‘worried well’.

Conclusions. Definition of MCI varies considerably dependent upon the tests used for case definition. The majority have other cognitive deficits despite normal performance on the Mini-mental State Examination (MMSE) and intact activities of daily living (ADL) and fit within multi-domain MCI. Pure amnesic MCI is rare.
Techniques for vibration control of a flexible robot manipulator
Authors: Mohamed Z. , Chee A. K. , Hashim A. W. I. Mohd , Tokhi M. O. , Amin S. H. M. , Mamat R.
Published: January 2006

This paper presents investigations into the applications and performance of positive and negative input shapers in command shaping techniques for the vibration control of a flexible robot manipulator. A constrained planar single-link flexible manipulator is considered and the dynamic model of the system is derived using the finite element method. An unshaped bang-bang torque input is used to determine the characteristic parameters of the system for design and evaluation of the input shaping control techniques. The positive and specified amplitude negative input shapers are designed based on the properties of the system. Simulation results of the response of the manipulator to the shaped inputs are presented in the time and frequency domains. Performances of the shapers are examined in terms of level of vibration reduction, time response specifications and robustness to parameters uncertainty. The effects of derivative order of the input shaper on the performance of the system are investigated. Finally, a comparative assessment of the impact amplitude polarities of the input shapers on the system performance is presented and discussed.
Modelling of a logarithmic parameter adaptation law for adaptive control of mechanical manipulators
Authors: Burkan Recep
Published: January 2006

In the paper, a new adaptive control law for controlling robot manipulators is derived based on the Lyapunov theory; trigonometric functions are used for the derivation of the parameter estimation law. In this note, we have derived a logarithmic parameter estimation law based on a previous paper, and the boundedness of tracking error has been shown.
The effects of solute-solvent electrostatic interactions on solvation dynamics in supercritical CO2
Authors: Ladanyi Branka M. , Nugent Severin
Published: January 2006

We present here the results of molecular-dynamics simulation of solvation dynamics in supercritical CO2 at a temperature of about 1.05Tc, where Tc is the critical temperature, and at a series of densities ranging from 0.4 to 2.0 of the critical density ρc. We focus on electrostatic solvation dynamics, representing the electronic excitation of the chromophore as a change in its charge distribution from a quadrupolar-symmetry ground state to a dipolar excited state. Two perturbations are considered, corresponding to different magnitudes of solute excited-state dipoles, denoted as d5 and d8. The d8 solute is more attractive, leading to a larger enhancement in CO2 clustering upon solute electronic excitation. This has a large impact on solvation dynamics, especially at densities below ρc. At these densities, solvation dynamics is much slower for the d8 than for the d5 solute. For both solutes, solvation dynamics becomes faster at densities above ρc at which solvent clustering diminishes. We show that the slowest solvation time scale is associated with solvent clustering and we relate it to solute-solvent mutual translational diffusion and the extent of change in effective local density resulting from solute electronic excitation.
Ferroelectric properties and fatigue behavior of heteroepitaxial PbZr1−xTixO3 thin film fabricated by hydrothermal epitaxy below Curie temperature
Authors: Ahn W. S. , Jung W. W. , Choi S. K.
Published: January 2006

A heteroepitaxial PbZr1−xTixO3 (PZT) thin film was fabricated by means of hydrothermal epitaxy at 210 °C below Curie temperature without undergoing the paraelectric to ferroelectric phase transition. From transmission electron microscope and piezoresponse force microscope observations, it was confirmed that the fabricated PZT thin films had only a −c monodomain without an a domain in the as-synthesized state. The polarization-electric-field hysteresis curve and the fatigue behavior of the heteroepitaxial PZT capacitor with a Pt top and n-type semiconductor bottom electrode was observed. The remanent polarization 2Pr of the PZT capacitor was about 63μC∕cm2. This value was much lower compared to that of the PbTiO3 capacitor, which was also fabricated by means of hydrothermal epitaxy at 160 °C below Curie temperature. It was suggested that a lower polarization of the PZT capacitor was due to the nonswitchable interfacial layer grown in the initial growth stage. However, this layer did not exert an influence on the fatigue behavior of the PZT capacitor: the PZT capacitor with an ordinary Pt top electrode and a Nb-doped SrTiO3 semiconductor bottom electrode revealed fatigue-free behavior in up to 1011 switching cycles.
Carrier dynamics study of the temperature- and excitation-dependent photoluminescence of InAs∕GaAs quantum dots
Authors: Nee Tzer-En , Wu Ya-Fen , Cheng Chao-Ching , Shen Hui-Tang
Published: January 2006

We investigate the effects that the carrier dynamics have on the temperature and excitation intensity dependence of the photoluminescence (PL) of self-assembled InAs∕GaAs quantum dot heterostructures having different size uniformities. We propose a rate equation model that takes into account the dot size distribution, the random population of density of states, and all of the important mechanisms of carrier dynamics, including radiative and nonradiative recombinations, thermal escaping and relaxing, and state filling effects. We used this model to simulate the PL spectra obtained from our samples; the results agree well with the measured data. We discuss in detail our quantitative calculations of the corresponding mechanisms of the thermal redistribution and state filling effects. These mathematical analyses provide distinct explanations for the phenomena we observed in the temperature- and incident power-dependent PL spectra of samples having different size uniformities.
Influence of polymer network in polymer-stabilized ferroelectric liquid crystals and its direct observation using a confocal microscope
Authors: Petkovšek R. , Pirš J. , Kralj S. , Čopič M. , Šuput D.
Published: January 2006

The paper presents the analysis of the three-dimensional polymer network distribution inside the polymer-stabilized ferroelectric liquid-crystal layer based on the laser scanning fluorescence confocal microscopy and a fluorescent dye tagging of the polymer. The studies of polymer-stabilized ferroelectric liquid-crystal structures described in this paper are focused on the comparison of the influence of polymer network in case that the polymerization is initiated in the chevron as well as in the quasibookshelf liquid-crystal molecular orientation. In the case of the chevron structure the regular distribution of the polymer network within the layer leads to the monostability of the chevron state. On the other hand the specific distribution of the polymer in the polymer-stabilized quasibookshelf stripe textures leads to the perfect bistability, improved multiplex driving, and analog gray scale capability.
Effect of incorporating an InAlAs layer on electron emission in self-assembled InAs quantum dots
Authors: Chen J. F. , Hsiao R. S. , Hsieh M. F. , Wang J. S. , Chi J. Y.
Published: January 2006

We perform capacitance-voltage and admittance spectroscopy to investigate the effect of incorporating an InAlAs layer before an InGaAs cap layer on electron emission in self-assembled InAs quantum dots (QDs). We show that this incorporation of a high potential barrier increases the emission time of the electrons thermally activated from the QD ground to the first excited state. The energy separation between the ground and first excited states in the conduction band increases from 57.2 to 79.1, to 89.2, and to 95.6 meV with increasing the thickness of the InAlAs layer from 0 to 10, to 14, and to 20 Å. Combining with photoluminescence (PL) data, the ratios of the energy separation between the ground and first excited states in the conduction band and valence band are determined to be 7.3:2.7 and 7.8:2.2 for 0 and 10 Å InAlAs, respectively. In addition, this incorporation is shown to blueshift the PL first excited state much larger than the ground state.
Band parameters and electronic structures of wurtzite ZnO and ZnO∕MgZnO quantum wells
Authors: Fan W. J. , Xia J. B. , Agus P. A. , Tan S. T. , Yu S. F. , Sun X. W.
Published: January 2006

The band structures of wurtzite ZnO are calculated by the empirical pseudopotential method (EPM). The eight parameters of the Zn and O atomic pseudopotential form factors are obtained with the formula of Schluter et al.[Phys. Rev. B 12, 4200 (1975)]. The band parameters are extracted by using a k∙p Hamiltonian to fit the EPM results. The calculated band-edge energies (Eg, EA, EB, and EC) at the Γ point are in good agreement with the experimental results. Based on the band parameters obtained, valence subbands of wurtzite ZnO∕MgxZn1−xO tensile-strained quantum wells with different well widths and Mg compositions are calculated by the six-band k∙p method.
Three- and four-μm-thick YBa2Cu3O7 layers with high critical-current densities on flexible metallic substrates by the BaF2 process
Authors: Solovyov Vyacheslav F. , Wiesmann Harold J. , Li Qiang , Welch David O. , Suenaga Masaki
Published: January 2006

We report on the synthesis and performance of 3- and 4-μm-thick YBa2Cu3O7 films on buffered metallic tapes. The precursor films were deposited by vacuum coevaporation of BaF2, Y, and Cu on the substrates and converted to YBa2Cu3O7 by the BaF2 ex situ process at reduced processing gas pressures. The best value of critical-current density Jc for these films was ∼3.8×103A∕mm2 at 77K and in 1T external magnetic field perpendicular to the film plane. Also, estimated critical-current densities per width of tape Jcw at zero magnetic field were ∼60 and ∼80A∕mm for 3- and 4-μm-thick films, respectively. In order to achieve these high-Jc values, the films were processed at high growth rates (∼0.7nm∕s) and the oxygen partial pressure p(O2) was varied to minimize the growth of the “granular” c axis and randomly oriented YBa2Cu3O7 grains. A simple thermodynamic argument is also given to describe the observed dependence of the nucleation of YBa2Cu3O7 with different orientations on p(O2). This result demonstrates the feasibility of fabricating coated conductors with a single YBa2Cu3O7 layer having the critical current of the order of 100A∕mm at self-field and liquid-N2 temperature.
Local vibration at the surface of a Ge nanocrystal embedded in a silicon oxide matrix
Authors: Yang Y. M. , Wu X. L. , Yang L. W. , Huang G. S. , Qiu T. , Shi Y. , Siu G. G. , Chu Paul K.
Published: January 2006

A low-frequency Raman vibration mode, whose peak position and linewidth are independent of the sizes of Ge nanocrystals and the polarization configuration of incident excitation light, was observed in silicon oxide films embedded with Ge nanocrystals which were prepared using magnetron cosputtering of SiO2–Ge–Si targets. The peak position of the Raman mode is sensitive to the content of Si in the matrix. After the sample is annealed above a special temperature that increases with the content of Si, the Raman mode disappears. Microstructural observations and spectral analyses disclose that this low-frequency Raman mode arises from a local structure which is positioned at the surfaces of Ge nanocrystals and consists of Ge, Si, and O atoms. High-temperature annealing leads to the removal of Ge atoms from the local structure. As a result, the local vibration mode vanishes.
Annealing-temperature dependence: Mechanism of Hf silicidation in HfO2 gate insulators on Si by core-level photoemission spectroscopy
Authors: Toyoda S. , Okabayashi J. , Takahashi H. , Kumigashira H. , Oshima M. , Niwa M. , Usuda K. , Liu G. L.
Published: January 2006

We have investigated the mechanism of Hf silicidation from HfO2 gate insulators on Si by high-resolution core-level photoemission spectroscopy with detailed annealing-temperature controlling. We have found that the silicidation temperature depends on the difference of the chemical states at the interfacial layer. The Hf-silicate layer which is more stable than the SiO2 layer prevents the silicidation. In addition, silicidation processes also promote the formation of SiO2. Chemical shifts in core-level photoemission spectra depend on the interfacial-layer thickness and SiO2 concentration in the HfO2 top layer, which are tunable by detailed annealing temperature.
Luminescence of bound excitons in epitaxial ZnO thin films grown by plasma-assisted molecular beam epitaxy
Authors: Jung Y. S. , Choi W. K. , Kononenko O. V. , Panin G. N.
Published: January 2006

Luminescence properties of ZnO films, which have been epitaxially grown on c-sapphire (0001) substrates by plasma-assisted molecular beam epitaxy, are investigated by means of different excitation sources and their measurement conditions. With the increase of measurement temperature, photoluminescence spectra clearly present, the appearance of different bound-exciton peaks (I10 line) with an abrupt increase of emission intensity at the measurement temperature of 30-50K. Hypothetical explanations on the basis of thermalization effects, vibronic/rotational resonance states, and the involvement of the B-valence level in emission are given. In cathodoluminescence (CL), the deep level emission intensity was enlarged with the electron beam penetration depth due to the higher defect density near the interface between ZnO and the sapphire. From the CL image of the ZnO film, the dislocation density was estimated as 6×108-3×109∕cm2. The lasing phenomenon was observed at the threshold power density of 1.3MW∕cm2 at 300K.
Electronic structure study by means of x-ray spectroscopy and theoretical calculations of the “ferric star” single molecule magnet
Authors: Takács A. F. , Neumann M. , Postnikov A. V. , Kuepper K. , Scheurer A. , Sperner S. , Saalfrank R. W. , Prince K. C.
Published: January 2006

The electronic structure of the single molecule magnet system {M[Fe(L1)2]3}∙4CHCl3 [M=Fe,Cr;L1=CH3N(CH2CH2O)22−] has been studied using x-ray photoelectron spectroscopy, x-ray-absorption spectroscopy, soft-x-ray emission spectroscopy, as well as theoretical density-functional-based methods. There is a good agreement between theoretical calculations and experimental data. The valence band mainly consists of three bands between 2 and 30eV. Both theory and experiments show that the top of the valence band is dominated by the hybridization between Fe3d and O2p bands. From the shape of the Fe2p spectra it is argued that Fe in the molecule is most likely in the 2+ charge state. Its neighboring atoms (O,N) exhibit a magnetic polarization yielding effective spin S=5∕2 per iron atom, giving a high-spin state molecule with a total S=5 effective spin for the case of M=Fe.
Approach to enhance the coercivity in perpendicular FePt∕Ag nanoparticle film
Authors: Li Bao-He , Feng Chun , Yang Tao , Hwang Pol , Teng Jiao , Yu Guang-Hua , Zhu Feng-Wu
Published: January 2006

[ FePt 2 nm ∕ Ag d nm ] 10 multilayers were prepared on 100 °C MgO (100) single-crystal substrates with magnetron sputtering. The ordering and perpendicular texture of L10-FePt∕Ag particle films with high coercive force were realized at a lower postannealing temperature and by controlling accurately the atomic ratio of Fe to Pt of L10-FePt films. The results of the x-ray-diffraction pattern show that the FePt particles have excellent (001) texture when the multilayers were sputtered on 100 °C substrates with the thickness of the Ag layer d=3–9nm, and the mean size of L10-FePt particles reduces with increasing thickness of the Ag layer. After the [FePt2nm∕Ag5nm]10 was vacuum annealed at 600 °C for 15 min, the mean size of L10-FePt particles is roughly about 8 nm and its perpendicular coercive force reaches 979kA∕m(12.3kOe). This particle film has little magnetic exchange coupling and is a candidate for future perpendicular magnetic recording media with ultrahigh density.