bluuebunny/crossref_metadata_2025 huggingface dataset:
Carbosilane Dendrons Functionalized at Their Focal Point
Authors: Andrés Román , de Jesús Ernesto , de la Mata F. Javier , Flores Juan C. , Gómez Rafael
Published: August 2005

The Si–Ph bond of PhSi[(CH2)3SiMe2Bz]3 (5) is cleaved with triflic acid to give TfOSi[(CH2)3SiMe2Bz]3, which, in turn, reacts with triethylammonium chloride or potassium cyclopentadienide to give, respectively, ClSi[(CH2)3SiMe2Bz]3 (8) and (C5H5)Si[(CH2)3SiMe2Bz]3 (10). This strategy can be applied to the post‐growth incorporation of nucleophiles to the focal point of carbosilane dendritic wedges. In this way, cyclopentadiene‐functionalized dendritic wedges of second and third generation C5H5‐Gn‐[(CH2)3SiMe2Bz]x (n = 2, x = 9, 11; n = 3, x = 27, 12) have been obtained starting from Ph‐Gn‐[(CH2)3SiMe2Bz]x (6, 7). The metallocenes [{(BzMe2SiCH2CH2CH2)3SiC5H4}2MCl2] (M = Ti, 14; Zr, 15) have also been obtained from 10 and their catalytic behavior in ethylene and propylene polymerization, using MAO as a cocatalyst, has been studied and compared to that of related non‐dendritic complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Bifunctional Bioorganometallic Iridium(III)–Platinum(II) Complexes Incorporating Both Intercalative and Covalent DNA Binding Capabilities
Authors: Gençaslan Susan , Sheldrick William S.
Published: August 2005

The DNA binding of bifunctional IrIII–PtII complexes containing [(η5‐Cp*)Ir(dppz)]2+ and [Pt(terpy)]2+ or trans‐[PtL2L′]2+ fragments (L = NH3, L′ = DMF; L = H2O, L′ = NH3) bridged by flexible κS:κN(amino)‐coordinated methionine‐containing peptides has been studied by UV/Vis and CD spectroscopy. Stable intercalative binding of the IrIII fragment of the complexes [{(η5‐Cp*)Ir(dppz)}(μ‐peptide‐κS:κN){Pt(terpy)}](CF3SO3)4 (5) (peptide = H‐Gly‐Gly‐Phe‐Met‐OH; H‐Gly‐OH = glycine, H‐Phe‐OH = L‐phenylalanine, H‐Met‐OH = L‐methionine) and 6 [peptide = H‐(Ala)4‐Met‐OH; H‐Ala‐OH = L‐alanine] is indicated by their steady decrease in absorbance at maxima between 350 and 390 nm on titration with CT DNA and by the bathochromic shifts of these maxima. Binding constants Kb of 1.4(4) × 106 M–1 for both 5 and 6 and site sizes s of 2.8(1) and 2.2(1), respectively, are in accordance with this monofunctional mode. Both peptide chain length and the site(s) of the labile PtII substituents DMF or H2O play an important role in determining the degree of intercalation of the IrIII fragment and the extent of helix distortion caused by simultaneous covalent binding of PtII centres for the DNA interaction of the complexes [{(η5‐Cp*)Ir(dppz)}(μ‐peptide‐κS:κN){trans‐(PtL2L′)}]4+ 7–10. Whereas both 9 and 10 (L = H2O, L′ = NH3; peptide = H‐Gly‐Met‐OH or H‐Gly‐Gly‐Met‐OH) exhibit a high degree of bifunctional binding [9, Kb = 1.1(5) × 106 M–1, s = 1.3(1); 10, Kb = 1.4(7) × 106 M–1, s = 2.1(1)], CD spectroscopy indicates that a more pronounced reorganisation of the DNA helix is required for the former complex with its shorter peptide. Effective intercalation is also observed for 8 (L = NH3, L′ = DMF; peptide = H‐Gly‐Gly‐Met‐OH) but not for 7 with the analogous PtII fragment but a shorter bridging peptide (H‐Gly‐Met‐OH). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Polycyclic aromatic hydrocarbons in vegetable oils from canned foods
Authors: Moret Sabrina , Purcaro Giorgia , Conte Lanfranco S.
Published: August 2005

A rapid method previously set up for polycyclic aromatic hydrocarbons (PAH) determination in vegetable oils was used to carry out a survey on 62 samples of vegetable oils from canned vegetables and fish and oil‐based sauces. Of the oil samples from vegetable products, 15% exceeded the 2‐ppb level for benzo(a)pyrene. The highest PAH concentration was found in the oil from a grilled mushroom sample, which presented 11.3 ppb of BaP and 47.1 ppb of total heavy PAH. Regarding the canned fish, none of the analyzed samples exceeded the limit for BaP. The highest contamination level was found in an olive oil sample from canned tuna: 1.9 ppb of BaP and 11.3 ppb of total heavy PAH. The high PAH concentrations found in some oil samples from vegetable products could be due to the contribution from contaminants in the vegetables.
Effect of channel structure on preparation of a water‐in‐oil emulsion by polymer microchannels
Authors: Liu Haijie , Nakajima Mitsutoshi , Nishi Taiji , Kimura Toshinori
Published: August 2005

Monodisperse water‐in‐oil emulsions were successfully prepared using a polymer microchannel (PMC) with hydrophobic properties and high anti‐alkalinity and fabricated by the molding injection method. We investigated the effect of the channel structure on the droplet preparation characteristics, including the average droplet diameter, the coefficient of variation (CV), the pressure range for stable droplet formation, and the critical flow velocity of the dispersed phase. Various PMC with different structures were fabricated and used for emulsification. The results indicated that the average droplet diameter and the CV did not change remarkably and that the critical flow velocity of the dispersed phase was increased slightly when we used PMC with different small rectangular‐shaped convexes in the channel. However, the pressure range for stable droplet formation widened, the CV decreased, and the critical flow velocity of the dispersed phase increased significantly with a decrease of the PMC equivalent diameter and an increase of the PMC length, which revealed greater stability and productivity of the emulsion droplets.
Isolation and evaluation of antioxidants from leaves of a Tunisian cultivar olive tree
Authors: Bouaziz Mohamed , Sayadi Sami
Published: August 2005

Quantitative and qualitative determinations of phenolic compounds were carried out on Chemlali olive leaves, a by‐product of olive tree pruning. The evolution of the amount of the major phenolic compound was monitored from July 2003 to March 2004. Quantitative analysis was performed by high‐performance liquid chromatography (HPLC), which revealed that oleuropein was always the major compound. Its concentration reached 6.8 g per 100 g of fresh olive leaves, while monomeric phenols were the minor compounds. Beside oleuropein, six flavonoids (luteolin 7‐O‐glucoside, luteolin 7‐O‐rutinoside, apigenin 7‐O‐glucoside, rutin, luteolin and apigenin) were identified. The identification was based on separation by HPLC equipped with a diode array detector, followed by liquid chromatography‐mass spectrometry analysis. A relative high amount of purified hydroxytyrosol (2.3 g per 100 g of fresh olive leaves) was obtained in short time by a simple hydrolysis reaction of Olea europaea leaf extract and by purification using a C‐18 silica gel column. The antioxidant activities of the extracts and the purified compounds were evaluated by measuring the radical‐scavenging effect on 1,1‐diphenyl‐2‐picrylhydrazyl and by using the β‐carotene linoleate model assay. Hydroxytyrosol and hydrolysate products have the highest antioxidant activities.
White Biotechnology for lipids, fats and oils
Authors: Bornscheuer Uwe T.
Published: August 2005

No abstracts.
Pyridine‐Based Oligonitriles as Pincer Ligands for Palladium(II), Copper(II), Cobalt(II), and Nickel(II) Ions
Authors: Behrens Henrik , Fröhlich Roland , Würthwein Ernst‐Ulrich
Published: August 2005

Nucleophilic ring opening of the 1‐oxa‐3,5‐diazinium salts 2 and 3 by propylamine furnishes the new polydentate, branched, pincer‐type ligands 4 and 5, respectively, in 34 and 57 % yield. The 1‐oxa‐3,5‐diazinium salts 2 and 3 were prepared from pyridine‐2,6‐dicarbonyl dichloride (1) by treatment with dimethylcyanamide and diisopropylcyanamide in the presence of antimony pentachloride and tin tetrachloride, respectively. The structure of 4, which is characterised by a strongly twisted N‐acyloligonitrile arm, was determined by X‐ray crystallography. The ligand 4, with its short and long arms, forms chelate complexes 4–·Pd(OAc)+ and 4·CuCl2 when treated with palladium(II) acetate and copper(II) chloride, respectively. 4–·Pd(OAc)+ shows remarkable catalytic activity in Suzuki–Miyaura cross‐coupling reactions. The pincer‐type ligand 5 gives the chelate complexes 5·Co(ClO4)2·DMF, 5·CoCl2 and 5·Ni(ClO4)2·DMF upon treatment with the respective metal salts. These three complexes show octahedral configuration, with DMF or chloride occuping the sixth coordination site. For the CoII complexes a cis configuration is oberserved for 5·CoCl2 and a trans configuration for 5·Co(ClO4)2·DMF. In all cases 5 acts as a pentadentate ligand. All metal complexes were characterised by X‐ray diffraction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Synthesis of 3‐ and 4‐Hydroxy‐2‐aminocyclohexanecarboxylic Acids by Iodocyclization
Authors: Szakonyi Zsolt , Gyónfalvi Szilvia , Forró Enikö , Hetényi Anasztázia , De Kimpe Norbert , Fülöp Ferenc
Published: August 2005

Starting from cis‐7‐azabicyclo[4.2.0]oct‐4‐en‐8‐one, novel routes have been developed for the synthesis of 2‐amino‐4‐hydroxycyclohexanecarboxylic acid and its 3‐hydroxy‐substituted analog via iodooxazine, iodooxazoline or iodolactone intermediates. After CAL‐B‐catalyzed enzymatic transformation of the starting β‐lactam, the iodolactone method was applied to the synthesis of 3‐hydroxy‐substituted β‐amino acid enantiomers. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Variability of EEG synchronization prior to and during observation and execution of a sequential finger movement
Authors: Calmels Claire , Holmes Paul , Jarry Gilbert , Hars Magaly , Lopez Emilie , Paillard Aurore , Stam Cornelis J.
Published: August 2005

The aim of this study was to test the validity of mirror neuron activity in humans through analysis of electroencephalographic (EEG) functional connectivity during an action not directed towards an object. We investigated changes in EEG interchannel synchronization prior to and during action execution and also prior to and during observation of the same action. Twelve participants observed a simple finger movement sequence. In a second testing session they physically executed the movement. EEGs were recorded from 19 active sites across the cortex. Activity was considered in four frequency bands (7–10 Hz, 10–13 Hz, 13–20 Hz, and 20–30 Hz) using a new measure: synchronization likelihood. This technique considers rapid changes in signal synchronization and spatiotemporal patterns of coherence. The results revealed no statistically significant difference in synchronization likelihood between the observation and execution data. We found an increase in synchronization over a broad frequency range during task processing and suggest that this may reflect interregional cortical coupling of intricately and hierarchically interconnected networks that are active in a similar way during both observation and execution of a movement. While EEG may be insensitive to differences present during the observation and execution of a movement, the results of the present study shed some light on the general mechanisms of cognitive integration. Hum Brain Mapp, 2005. © 2005 Wiley‐Liss, Inc.
Convergence of behaviour change models for AIDS risk reduction in sub‐Saharan Africa
Authors: Odutolu Oluwole
Published: August 2005

There is increasing programme focus on the impact of HIV and AIDS and the advances in biomedical research that are taking central stage even in sub‐Saharan Africa. Perhaps out of frustration, communication and behaviour change efforts are receiving lesser attention. But as long as heterosexual intercourse remains the predominant means of transmission of HIV in sub‐Saharan Africa, there is the inherent danger of more people getting infected thus mopping up the gains from other approaches. This paper therefore argues for evidence based behaviour change interventions in sub‐Saharan Africa, revisits the behaviour change theories and their relevance to the African situation. It proposes an integration of models based on the convergence of three existing theories of social learning, diffusion of innovation and social networks and the author's understanding of some African culture. The beauty of the model is based on the fact that ‘social norms are best understood and influenced at the level of social networks’; existing chains of communication and the naturalness of exchange of information. A case is made for application of the ‘model’ to precipitate sexual behaviour change and HIV reduction in sub‐Saharan Africa. Copyright © 2005 John Wiley & Sons, Ltd.
The Shanghai case: a qualitative evaluation of community health reform in response to the challenge of population ageing
Authors: Wei Xiaolin , Zakus David , Liang Hong , Sun Xiaoming
Published: August 2005

Shanghai's health care system is facing a serious challenge of an ageing population, as 14% of its 17 million residents are 65 or older. In 2000, a community health reform was implemented to provide comprehensive and continuous primary care to community residents with a focus on seniors. The study employed the theoretical framework of examining primary care in terms of the constellation of its four unique elements (first contact, comprehensiveness, longitudinality and coordination) and three healthcare components (structure, process and outcome). The study aimed to evaluate the extent to which the reform has achieved its process goals and how the organizational context influenced the level of implementation. In‐depth interviews with 25 health providers, 15 seniors and four community leaders were carried out. The study found that the Shanghai community health reform has improved the structure and process of primary care regarding first contact, comprehensiveness and longitunality. However, the reform is constrained by structural barriers on seniors' financial access to resources and the capacity of primary care providers. The previous organization system also constrains the reform in CHCs financing and administration. The Shanghai case illustrates that a broad societal view has to be taken when analysing health reforms, which requires the involvement of multiple sectors including the government, health providers and health consumers. Copyright © 2005 John Wiley & Sons, Ltd.
In vitro and in vivo analysis of macroporous biodegradable poly(D,L‐lactide‐co‐glycolide) scaffolds containing bioactive glass
Authors: Day Richard M. , Maquet Véronique , Boccaccini Aldo R. , Jérôme Robert , Forbes Alastair
Published: August 2005

Recent studies have demonstrated the angiogenic potential of 45S5 Bioglass®. However, it is not known whether the angiogenic properties of Bioglass® remain when the bioactive glass particles are incorporated into polymer composites. The objectives of the current study were to investigate the angiogenic properties of 45S5 Bioglass® particles incorporated into biodegradable polymer composites. In vitro studies demonstrated that fibroblasts cultured on discs consisting of specific quantities of Bioglass® particles mixed into poly(D,L‐lactide‐co‐glycolide) secreted significantly increased quantities of vascular endothelial growth factor. The optimal quantity of Bioglass® particles determined from the in vitro experiments was incorporated into three‐dimensional macroporous poly(D,L‐lactide‐co‐glycolide) foam scaffolds. The foam scaffolds were fabricated using either compression molding or thermally induced phase separation processes. The foams were implanted subcutaneously into mice for periods of up to 6 weeks. Histological assessment was used to determine the area of granulation tissue around the foams, and the number of blood vessels within the granulation tissue was counted. The presence of Bioglass® particles in the foams produced a sustained increase in the area of granulation tissue surrounding the foams. The number of blood vessels surrounding the neat foams was reduced after 2 weeks of implantation; however, compression‐molded foams containing Bioglass® after 4 and 6 weeks of implantation had significantly more blood vessels surrounding the foams compared with foams containing no Bioglass® at the same time points. These results indicate that composite polymer foam scaffolds containing Bioglass® particles retain granulation tissue and blood vessels surrounding the implanted foams. The use of this polymer composite for tissue engineering scaffolds might provide a novel approach for ensuring adequate vascular supply to the implanted device. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Preparation of thermosensitive microgels via suspension polymerization using different temperature protocols
Authors: Zhang Ying , Zhu Wen , Ding Jiandong
Published: August 2005

A thermosensitive and biodegradable microgel for protein drug release was synthesized from a thermosensitive macromer via inverse suspension polymerization. Preparation was made under a constant temperature or under variable temperatures. In the latter protocol, dispersion was performed at a low temperature below lower critical solution temperature of the macromer aqueous solution and polymerization was performed at a high temperature above lower critical solution temperature. According to the experiments, the constant‐temperature method was not suitable for preparation of microgels when the macromer concentration was high, because early physical gelation at the preparation temperature seriously influenced formation of dispersed droplets. If the macromer concentration was low, both temperature protocols resulted in spherical hydrogel microparticles, but the properties of the resulting microgels were different to a certain degree. In both cases, the model protein bovine serum albumin was loaded into microgels by a postfabrication encapsulation technique, which takes advantage of the microgels' negative thermosensitivity. The results demonstrate that, in microgel preparation, the variable‐temperature protocol is useful in suspension polymerization of negatively thermosensitive macromers at a wide rage of monomer concentrations. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Controlling Drug Release from Imprinted Hydrogels by Modifying the Characteristics of the Imprinted Cavities
Authors: Hiratani Haruyuki , Mizutani Yuri , Alvarez‐Lorenzo Carmen
Published: August 2005

Summary: The aim of this study was to analyse the influence of the template/functional monomer proportion on the achievement of molecularly imprinted hydrogels with cavities with a high enough affinity for the drug to sustain drug release. Imprinted hydrogels were prepared from N,N‐dimethylacrylamide and tris(trimethylsiloxy)sililpropyl methacrylate (DMAA and TRIS; main components), methacrylic acid (MAA; functional monomer), ethylene glycol dimethacrylate (EGDMA; cross‐linker), and timolol (template drug). Photo‐polymerization of the monomer solutions was carried out in poly(propylene) molds (0.3 mm thickness) to obtain contact lens‐like devices. Non‐imprinted control hydrogels were also prepared in the same way but without the addition of timolol. The imprinted hydrogels showed a higher affinity for timolol and a slower release rate than the non‐imprinted hydrogels. The release rate decreased by increasing the MAA/timolol ratio in the gel recipe. Hydrogels prepared with 400 × 10−3 M MAA, 600 × 10−3 M EGDMA, and a timolol/MAA mole ratio of 1:16–1:32 had drug diffusion coefficients two orders of magnitude below those of non‐imprinted hydrogels. The results obtained clearly indicate that the timolol release rate is critically affected by the conditions under which the hydrogels were synthesized. These effects are discussed on the basis of the influence of drug proportion on the conformation of the imprinted cavities.

Timolol release profiles, in 0.9% NaCl at 25 °C, from the non‐imprinted and imprinted hydrogels prepared with 0.400 M MAA, 0.600 M EGDMA, and timolol (the ratio of timolol to MMA is as shown). Data are expressed as mean ± S.D. (n = 5).

magnified image

Timolol release profiles, in 0.9% NaCl at 25 °C, from the non‐imprinted and imprinted hydrogels prepared with 0.400 M MAA, 0.600 M EGDMA, and timolol (the ratio of timolol to MMA is as shown). Data are expressed as mean ± S.D. (n = 5).
Schematic Models of Molecular Self‐Organization
Authors: Van Workum Kevin , Douglas Jack F.
Published: August 2005

Molecular self‐organization is central to the formation of numerous biological structures and the emulation of this process through the creation of synthetic counterparts offers great promise for nanofabrication. Our approach to understanding the principles governing this process is inspired by existing models and measurements on the self‐organization of actin, tubulin and the ubiquitous icosahedral structures of viral capsids. We introduce a family of simple potentials that give rise to the self‐organization of chain‐like, random surface (‘membrane’), tubular (‘nanotube’) and hollow icosahedral structures that are similar in many respects to their biological counterparts.
Polymeric Scaffolds for Cartilage Tissue Engineering
Authors: Li Wan‐Ju , Tuan Rocky S.
Published: August 2005

Polymeric scaffolds are three‐dimensional, porous structures that may be used as a vehicle to deliver cells or therapeutic factors to repair tissue defects. Both biodegradable and non‐biodegradable polymers have been developed for this purpose. In this review, we survey the polymers that have been investigated for cartilage tissue engineering and discuss the critical parameters for successful applications in the future.
Poly(vinyl alcohol)‐Amino Acid Hydrogels Fabricated into Tissue Engineering Scaffolds by Colloidal Gas Aphron Technology
Authors: Donaldson Elizabeth , Cuy Janet , Nair Prabha , Ratner Buddy
Published: August 2005

A new class of hydrogels made from poly(vinyl alcohol) (PVA) and amino acid was formed into porous tissue engineering scaffolds by the colloidal gas aphron (CGA) method. CGA microfoams are formed using high speed stirring to generate uniform, micrometer scale bubbles. CGAs offer several advantages over conventional scaffold fabrication techniques including room temperature processing, aqueous conditions and utilization of air bubbles to create uniform pores. This technique eliminates the need for toxic solvents and salt templates. In addition, the novel poly(vinyl alcohol) hydrogels are inherently strong, eliminating the need for crosslinkers.
Electrostatically Self‐Assembled Multilayers of Chitosan and Xanthan Studied by Atomic Force Microscopy and Micro‐Interferometry
Authors: Maurstad Gjertrud , Bausch Andreas R. , Sikorski Pawel , Stokke Bjørn T.
Published: August 2005

The thickness and surface morphology of electrostatically self‐assembled films of chitosan and xanthan (persistence length of ∼120nm) have been studied using dual‐wavelength Reflection Interference Contrast Microscopy (DW‐RICM) and tapping mode Atomic Force Microscopy (AFM). The multilayers were prepared at two ionic strengths (5mM and 150mM). When the multilayers were assembled at 150 mM a network like morphology was observed after one bilayer. This structure was found to be of large influence in the further growth of the multilayers, with the same kind of network structure being observed at all number of bilayers. A lack of swelling behaviour, as well as the network structure and the poresize of the network, is suggested to originate from the high chain stiffness of xanthan.
Hydrogel Nanocomposite as a Synthetic Intra‐Ocular Lens Capable of Accommodation
Authors: Ravi Nathan , Aliyar Hyder Ali , Hamilton Paul D.
Published: August 2005

A hydrogel nanocomposite was designed, synthesized, and evaluated for use as an auto‐focusing intra‐ocular lens. The hydrogel scaffold was composed of a monomer‐free, thiol that contained polyacrylamide (5%), which was allowed to gel in the presence of nanoparticles at pH 7.4, 25°C. The nanoparticles consisted of a proteo‐mimetic polyacrylamide nanogel (∼42 nm), bovine serum albumin (BSA) (∼6 nm), and hydrophilized silica (∼3 nm). The extent of nanoparticle loading increased with decreasing particle size. The elastic modulus increased with increasing loading of the proteo‐mimetic nanogels and BSA, and it decreased with hydrophilized silica. In this investigation, the hydrogel that contained silica was the most promising class of nanocomposite hydrogels with properties comparable to that of a young porcine lens. A nanocomposite that consisted of 10% hydrogel scaffold and 24% hydrophilized silica (elastic [E] modulus of ∼1.0 kPa and refractive index [RI] of 1.42) was injected into a pre‐evacuated porcine lens capsular bag. The composite lens was evaluated in a custom‐designed four‐arm radial stretcher, and its force‐time spectrum was characterized by time constants of 60 ± 8.9 and 800 ± 32 ms. These results were comparable to a young porcine lens (E Modulus of 1.2 kPa; RI of 1.4105; time constants of 48.3 ± 0.58 and 668 ± 24.6 ms, respectively)
Three‐Dimensional Nanoparticle Arrays Templated by Self‐Assembled Block‐Copolymer Gels
Authors: Pozzo Danilo C. , Walker Lynn M.
Published: August 2005

Water‐soluble triblock copolymers (PEO‐PPO‐PEO) are utilized to provide thermoreversible micellar templates for three‐dimensional nanoparticle arrays. The triblock forms a cubic micellar structure with typical dimensions of tens of nanometers. The temperature‐dependent amphiphilic nature of the block copolymers provides increased structure control and allows the use of pre‐made silica and gold nanoparticles as well as globular proteins. Using rheology and small‐angle neutron scattering (SANS), we characterize the influence of the nanoparticles on the local particle structure and on the macroscopic mechanical properties. We are able to incorporate significant quantities of nanoparticles into the block copolymer gel without destroying the ordered structure. Contrast matching SANS demonstrates that some level of the template structure is transferred to the nanoparticles. This study demonstrates the feasibility and potential of using this simple approach to generate novel nanoparticles‐polymer composites.
Probing the Hydrodynamic Behavior of Drug‐Induced Tubulin Rings by Fluorescence Correlation Spectroscopy
Authors: Boukari Hacène , Sackett Dan L. , Nossal Ralph
Published: August 2005

We describe fluorescence correlation spectroscopy measurements of tubulin polymers composed of tubulin and either of two cytotoxic peptides – dolastatin 10 and cryptophycin 1. These peptides inhibit tubulin polymerization into microtubules, a major component of cellular networks, and instead induce the formation of predominantly single‐walled tubulin rings. We determine ratios of the hydrodynamic diameter of dolastatin‐tubulin or cryptophycin‐tubulin polymers to that of tubulin dimers, which are compared with corresponding ratios calculated for two simple models: 1) a circular ring made with N contiguous spherical beads and 2) a circular ring constructed with N non‐spherical monomers, each monomer being represented by 21‐minibeads. We find that the computed ratios from the 21‐minibead representation agree well with the measured ones when N = 28 and N = 16 for dolastatin‐tubulin and cryptophycin‐tubulin ring polymers, respectively. That is, the rings are made with 14 and 8 tubulin dimers, confirming the numbers derived by other techniques. The present results further support the applicability of theories that have been developed for calculating hydrodynamic properties of supramolecular biological structures.
Actin Polymerization in a Thermal Gradient
Authors: Pomerance Andrew , Matthews Jermey , Ferguson Matthew , Urbach Jeffrey S. , Losert Wolfgang
Published: August 2005

Actin polymerization was studied as a function of temperature and in controlled thermal gradients. In the absence of a thermal gradient, we observe a polymerization transition with a temperature increase of less than 10K, and we verify that microrheology provides a local measure of the polymerized fraction. Both of these results are in good agreement with prior observations. Thermal gradients allow us to generate polymerization gradients. This polymerization gradient induces motion in embedded microspheres that is not seen in control samples.
Controlled Release from and Tissue Response to Physically Bonded Hydrogel Nanoparticle Assembly
Authors: Hu Zhibing , Xia Xiaohu , Marquez Manuel , Weng Hong , Tang Liping
Published: August 2005

Our recent work on synthesis and application of thermally gelling nanoparticle dispersions is briefly reviewed here. These nanoparticles consist of interpenetrating polymer networks (IPN) of poly‐acrylic acid (PAAc) and poly(N‐isopropylacrylamide) (PNIPAM). The aqueous IPN nanoparticle dispersions with polymer concentrations above 2.5 wt % underwent an inverse thermoreversible gelation at about 33 °C. Dextran markers of various molecular weights as model macromolecular pseudodrugs were mixed with the IPN nanoparticle dispersion at room temperature. At body temperature, the dispersion became a gel. The dextran release profiles were then measured using UV‐visible spectroscopy. The biocompatibility of this nanoparticle assembly was assessed using an animal implantation model.
Pulsatile Release of Insulin from Layer‐by‐Layer Assembled Microgel Thin Films
Authors: Nolan Christine M. , Serpe Michael J. , Lyon L. Andrew
Published: August 2005

We describe studies concerning the construction and characterization of insulin‐impregnated poly(N‐isopropylacrylamide‐co‐acrylic acid) microgel thin films prepared by Layer‐by‐Layer (LbL) polyelectrolyte assembly. These films can be built up in a highly uniform fashion and display linear buildup dependence even up to 30 layers. Thermoresponsivity of these drug loaded films can be utilized to obtain extended pulsatile release of insulin over many cycles. Continuous thermal pulsing allows solubilization of the embedded peptide and subsequent diffusion through the film layers. The magnitude of release can be tuned based on film thickness. This type of microgel thin film construct proves to be extremely robust and can potentially pulse out constant bursts of peptide for more than one month at a time.
Features of the Morphology of 2‐Hydroxyethyl Acrylate ω‐Polymer
Authors: Rozenberg Boris , Chalykh Anatolii
Published: August 2005

Ω‐Polymer of 2‐Hydroxyethyl acrylate (HEA) with nanoporous morphology is formed and characterized. Some kinetic peculiarities and mechanism of HEA low‐temperature ω‐polymerization is discussed. It is suggested to use ω‐polymerization of vinyl monomers for preparation of functionalized nanoporous polymer composites for different .technical and biomedical applications.
Design of a planar half‐circle‐shaped UWB notch antenna
Authors: Lee Hyo K. , Park Jong K. , Lee Jung N.
Published: August 2005

In this paper, we propose a small, lightweight, and low‐cost ultra‐wideband (UWB) antenna that exhibits a notch characteristic in the 5‐GHz WLAN band (5.15–5.825 GHz) using a planar half‐circle shape patch, a two‐step matching stub, a coplanar waveguide (CPW)‐type feed, and a hat‐shaped slot. The notch frequency of the proposed antenna can be adjusted by controlling the slot length. The measured results are in reasonably good agreement with the simulated results. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 9–11, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21065
Loaded frequency selective surface
Authors: Gao Qiang , Yan Dun‐Bao , Fu Yun‐Qi , Yuan Nai‐Chang
Published: August 2005

In this paper a new frequency‐selective surface (FSS) with loadings, is introduced and analyzed using period moments methods. The simulated results show that FSS may operate in different bands and especially generate a large reduction in the resonant frequency for a fixed unit‐cell size through different loadings. This provides a new orientation for FSS development. Practical circuits are fabricated, and the measured results basically agree well with the simulated ones. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 47–49, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21077
Modeling of lossy multiregion substrates in microelectronic circuits using time‐domain surface integral equations
Authors: Yang Chuanyi , Jandhyala Vikram
Published: August 2005

In this work, the electromagnetic modeling of multiregion, finite‐sized lossy substrates in microelectronic circuits is carried out utilizing time‐domain surface integral equations. To reduce the additional computational complexity in the implementation caused by the decaying “wake” of the Green's function in lossy media, the resulting temporal convolution is addressed by the creation and use of an a priori exponential fitting table for discrete distances through Prony's method. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 68–73, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21084
Doppler effects in a left‐handed material: A first‐principles theoretical study
Authors: Xiao Sanshui , Qiu Min
Published: August 2005

The Doppler effects for the reflected wave from moving media are systemically analyzed in this paper. The theoretical formula for the Doppler shift in left‐handed material, which is described by Drude's dispersion model, is presented. This formula is examined by first‐principles numerical experiments, which are in agreement with the theoretical results. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 76–79, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21086
Multidomain pseudospectral time‐domain method for computation of electromagnetic scattering by bodies of revolution
Authors: Shi Yan , Su Tao , Liang Chang‐Hong
Published: August 2005

We present a multidomain pseudospectral method using cylindrical and spherical coordinates for the accurate and efficient time‐domain computation of scattering by bodies of revolution (BOR). In the BOR formulation of Maxwell's equations, the Fourier collocation method is utilized in the azimuthal direction and the Chebyshev collocation method in the other directions. Using the complex‐coordinate‐stretching approach, the strongly well‐posed perfectly matched layer (PML) formulations are derived in cylindrical and spherical coordinates. A comparison of the results obtained using the multidomain pseudospectral method and those using the finite‐difference time‐domain (FDTD) method clearly illustrates the superiority of the algorithm developed in this paper. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 92–96, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21091
Novel sulfobetaine‐sulfonic acid‐contained superswelling hydrogels
Authors: Kabiri Kourosh , Faraji‐Dana Sara , Zohuriaan‐Mehr Mohammad J.
Published: August 2005

Novel hydrogels based on zwitterionic monomer [3‐(methacrylamido)propyl] dimethyl (3‐sulfopropyl) ammonium hydroxide (MPDSAH) and a strong acid monomer (2‐acrylamido‐2‐methylpropane sulfonic acid, AMPS) were synthesized through solution polymerization under normal conditions to achieve nearly quantitative gel yield. The structure of the gels was confirmed using infrared spectroscopy. Thermal properties were simultaneously studied by differential scanning calorimetry and thermogravimetric analysis (DSC/TGA). The effects of the polymerization variables on the swelling capacity of the products were investigated. It was found that, in a certain range of the monomers mol ratio, increase of AMPS content was surprisingly accompanied with swelling reduction. The swelling exhibited lower sensitivity to the crosslinker concentration (range 0.6–1.2 wt%) compared with the conventional superabsorbents. However, in contrast with the conventional acrylic acid‐based superabsorbents, the neutralization degree of AMPS part of the new gels had only a small enhancing effect on their swelling capacity. The effect of total monomer concentration on the hydrogel absorbency was also studied. The fully ionic hydrogels showed an unusual pH‐independency behavior, so that their absorbency was nearly unchanged in a wide range of pH. Such unexpected behavior was also observed for the swelling in the ionic environments with various ionic strengths. Copyright © 2005 John Wiley & Sons, Ltd.
Automated parallel anionic polymerizations: Enhancing the possibilities of a widely used technique in polymer synthesis
Authors: Guerrero‐Sanchez Carlos , Abeln Caroline , Schubert Ulrich S.
Published: August 2005

Anionic polymerization techniques have been implemented successfully in a commercial automated synthesizer. The main problems for a successful adaptation of the experimental technique in the automated synthesizer are addressed, as well as some simple potential applications, such as the anionic polymerization of styrene, isoprene, and methyl methacrylate. The obtained results were reproducible and in concordance with literature knowledge. The apparent rate constant of the anionic polymerization of styrene in cyclohexane initiated bysec‐butyllithium could be determined at two different concentrations of the monomer and initiator in a temperature range of 10–60 °C. All the synthesis and characterization experiments of the polymers were performed within a short time period. Moreover, the syntheses of poly(styrene‐b‐isoprene) and poly(styrene‐b‐methyl methacrylate) block copolymers were also successfully carried out within the automated synthesizer. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4151–4160, 2005
A study on correlation between physical properties and interfacial characteristics in highly loaded graphite–polymer composites
Authors: Arai Toshihiro , Tominaga Yoichi , Asai Shigeo , Sumita Masao
Published: August 2005

Highly loaded graphite–polymer composites for a bipolar plate of polymer electrolyte fuel cell are studied. One of the composites contains of polypropylene (PP), and graphite powder and the other contains of poly(vinylidene fluoride) (PVDF) and the graphite, respectively. The electrical and physical properties for the composites are determined. Inverse gas chromatography (IGC) measurements are carried out to characterize the surface of the graphite and the interface between the graphite and each polymer, following the Fowkes scheme. The IGC measurements show that the surface of graphite is nucleophilic and strongly attracts electrophiles by acid–base interaction. It is considered to be reasonable that the main chain carbon atoms to which electronegative fluorine atoms bond in PVDF are nucleophilic and has strong acid–base interaction with graphite. Such strong interaction causes high electric resistivity, high flexural properties, and high melt viscosity of the composite. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2568–2577, 2005
Intimate blending of binary polymer systems from their common cyclodextrin inclusion compounds
Authors: Uyar Tamer , Rusa Cristian C. , Wang Xingwu , Rusa Mariana , Hacaloglu Jale , Tonelli Alan E.
Published: August 2005

A procedure for the formation of intimate blends of three binary polymer systems polycarbonate (PC)/poly(methyl methacrylate) (PMMA), PC/poly(vinyl acetate) (PVAc) and PMMA/PVAc is described. PC/PMMA, PC/PVAc, and PMMA/PVAc pairs were included in γ‐cyclodextrin (γ‐CD) channels and were then simultaneously coalesced from their common γ‐CD inclusion compounds (ICs) to obtain intimately mixed blends. The formation of ICs between polymer pairs and γ‐CD were confirmed by wide‐angle X‐ray diffraction (WAXD), fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). It was observed [solution 1H nuclear magnetic resonance (NMR)] that the ratios of polymers in coalesced PC/PMMA and PC/PVAc binary blends are significantly different than the starting ratios, and PC was found to be preferentially included in γ‐CD channels when compared with PMMA or PVAc. Physical mixtures of polymer pairs were also prepared by coprecipitation and solution casting methods for comparison. DSC, solid‐state 1H NMR, thermogravimetric analysis (TGA), and direct insertion probe pyrolysis mass spectrometry (DIP‐MS) data indicated that the PC/PMMA, PC/PVAc, and PMMA/PVAc binary polymer blends were homogeneously mixed when they were coalesced from their ICs. A single, common glass transition temperature (Tg) recorded by DSC heating scans strongly suggested the presence of a homogeneous amorphous phase in the coalesced binary polymer blends, which is retained after thermal cycling to 270 °C. The physical mixture samples showed two distinct Tgs and 1H T1ρ values for the polymer components, which indicated phase‐separated blends with domain sizes above 5 nm, while the coalesced blends exhibited uniform 1H spin‐lattice relaxation values, indicating intimate blending in the coalesced samples. The TGA results of coalesced and physical binary blends of PC/PMMA and PC/PVAc reveal that in the presence of PC, the thermal stability of both PMMA and PVAc increases. Yet, the presence of PMMA and PVAc decreases the thermal stability of PC itself. DIP‐MS observations suggested that the degradation mechanisms of the polymers changed in the coalesced blends, which was attributed to the presence of molecular interactions between the well‐mixed polymer components in the coalesced samples. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2578–2593, 2005
Relationship between FEV1 and peak oxygen uptake in children with cystic fibrosis
Authors: Pianosi Paul , LeBlanc John , Almudevar Anthony
Published: August 2005

Cross‐sectional data do not truly convey the manner in which declining lung function affects peak oxygen uptake (peak $\dot VO_2$) within a given patient with cystic fibrosis. We hypothesized that there would be a concomitant decline in peak $\dot VO_2$ with FEV1 over time. Twenty‐eight children aged 8–17 years with cystic fibrosis performed annual ergometer tests over a 5‐year period to determine peak $\dot VO_2$ and within‐patient predictors of change in peak $\dot VO_2$. Analysis was done using a mixed‐effects model. During the study period, the annual decline in FEV1 averaged 2.7% of the predicted value per year. Peak $\dot VO_2$ fell during the observation period in 70% of patients, with an average annualized decline of 1.9 ml · min−1 · kg−1. This rate of decline was greater in older children in contrast to younger children, some of whom had an improvement in peak $\dot VO_2$ over the first few years, consistent with growth and maturation. There was no difference in this rate of decline between sexes, but girls started with a slightly lower peak $\dot VO_2$ (37.9 vs. 45.1 ml · min−1 · kg−1). In patients with FEV1 <80% predicted, declining FEV1 was highly correlated with falling peak $\dot VO_2$, whereas it remained stable over 4–5 years in patients whose FEV1 was >80% predicted and remained in that range. We conclude that peak $\dot VO_2$ remains stable or rises slightly over time in younger patients, while it shows a downward trend in older children with CF, particularly once FEV1 falls below 80% predicted. Peak $\dot VO_2$ is correlated with FEV1 during childhood in patients with cystic fibrosis, and both FEV1 and age influence peak $\dot VO_2$. Pediatr Pulmonol. © 2005 Wiley‐Liss, Inc.
Properties of intergrowths and partial dislocations in mercury‐based HTSC oxides
Authors: Eyidi Dominique , Tall Papa D. , Rabier Jacques
Published: August 2005

Intergrowths, stacking faults and dislocations have been investigated by transmission electron microscopy in (Hg, Re)Ba2Ca2Cu3O8+δ and HgBa2CaCu2O6+δ bulk superconductors. The stacking fault vectors and the Burgers vectors of partial edge dislocations associated with the nucleation or the annihilation of [Ca–CuO2] bilayers in the unit cells of both compounds are derived by different methods. We discuss the influence of uniaxial stresses on intergrowth propagation and also mechanisms yielding strain relaxation around intergrowths. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical studies on effective interactions in two‐band system
Authors: Nagao Hidemi , Kawabe Hiroyuki
Published: August 2005

We investigate effective interactions in a two‐dimensional two‐sublattice system by using a two‐band Hubbard model. We present a t‐matrix approach for two‐dimensional two‐sublattice system and derive expressions of effective interactions by using the t‐matrix approach. Expressions of the effective exchange integral in the Heisenberg model are also approximately derived. The results suggest that two‐band superconductivity appears in the limit of an almost‐empty or almost‐filled band and strongly electron–electron correlation in two‐band systems. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Model checking, testing and verification working together
Authors: Gunter Elsa , Peled Doron
Published: August 2005

We present a symbolic model checking approach that allows verifying a unit of code, e.g., a single procedure or a collection of procedures that interact with each other. We allow temporal specifications that assert over both theprogram countersand theprogram variables. We decompose the verification into two parts: (1) a search that is based on the temporal behavior of theprogram counters, and (2) the formulation and refutation of a path condition, which inherits conditions constraining theprogram variablesfrom the temporal specification. This verification approach is modular, as we do not require that all the involved procedures are provided. Furthermore, we do not request that the code is based on a finite domain. The presented approach can also be used for automating the generation of test cases for unit testing.
Effectiveness of clozapine, olanzapine, quetiapine, risperidone, and haloperidol monotherapy in reducing hostile and aggressive behavior in outpatients treated for schizophrenia: a prospective naturalistic study (IC-SOHO)
Authors: Bitter Istvan , Czobor Pal , Dossenbach Martin , Volavka Jan
Published: August 2005

Objective

Antipsychotic medications may reduce hostile and aggressive behavior in schizophrenia. This study compared the effectiveness of antipsychotics in the treatment of aggression.

Method

The Intercontinental Schizophrenia Outpatient Health Outcomes (IC-SOHO) study compares the effectiveness of antipsychotic treatments in practice setting. Schizophrenia outpatients who initiated or changed to a new antipsychotic are followed in this non-interventional, prospective observational study for up to 3 years, with 6-months data now available on the entire cohort (N = 7655). The presence or absence of verbal or physical hostility/aggression was assessed retrospectively for the period of 6 months before enrollment, and prospectively in the period of 6 months after enrollment (the study treatment period). At baseline, patients in five monotherapy treatment groups (combined N = 3135) were prescribed one of the treatments: clozapine, olanzapine, quetiapine, risperidone, or haloperidol, and had complete data.

Results

Hostile/aggressive behavior was reduced during the treatment period. Olanzapine and risperidone were significantly superior to haloperidol and to clozapine in this respect. These results remained essentially unchanged when adjusting for baseline imbalances in age, gender, age of onset, and substance abuse.

Conclusions

As monotherapy, both olanzapine and risperidone were superior to haloperidol and clozapine in reducing aggression. The relative lack of effectiveness of clozapine may be specific to this study population.