bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Temperature on Morphology and Properties of Films Prepared from Poly(ester‐urethane) and Nitrochitosan
Authors: Zeng Ming , Zhang Lina 
Published: January 2006

AbstractSummary: Novel elastic materials were prepared by mixing semicrystalline polyester‐based polyurethane (PU) synthesized at 100 °C with nitrochitosan (NCH) and 1,1,1‐tris(hydroxylmethyl)propane as crosslinker, and then by curing the mixture at 18, 25, 40, 60, and 80 °C. The effects of cure temperature on the crystallization behavior, miscibility, and mechanical properties of the PUNCH materials were studied by attenuated total reflection Fourier transform IR, wide‐angle X‐ray diffraction, scanning electron microscopy, dynamic mechanical analysis, X‐ray photoelectron spectroscopy, and tensile test. The results indicated that the crystalline structure of the blend films was more easily interrupted as the cure temperature increased, leading to a decrease of the degree of crystallinity. With an increase of cure temperature, the blend films exhibited high crosslinking density and tensile strength, and the phase separation between hard and soft segments of PU enhanced, resulting in a decrease in the glass transition temperature (Tg) of soft segment. Interestingly, the composite films keeping high elongation at break possessed tensile strength higher than that of the native poly(ester‐urethane). The enhanced mechanical properties of the blend films can be attributed to the relatively dense crosslinking network and strong intermolecular hydrogen bonding between NCH and PU. Therefore, this study not only provided a novel way by adding NCH into PU matrix to prepare elastic materials, which would remain functional characteristic of chitosan, but also expanded the application field of chitosan.The cure temperature dependence of the tensile strength and elongation at break for the PEPU‐100 and PUNCH‐100 films.imageThe cure temperature dependence of the tensile strength and elongation at break for the PEPU‐100 and PUNCH‐100 films.
Click Chemistry with Polysaccharides
Authors: Liebert Tim , Hänsch Claudia , Heinze Thomas 
Published: January 2006

AbstractSummary: The copper‐catalyzed Huisgen reaction as a typical example of click chemistry was realized with the polysaccharide cellulose for the first time. The generality, selectivity, and the efficiency of click chemistry perfectly fit the requirements of polysaccharide modification, which is demonstrated by the introduction of triazole‐spacer bound functional groups, i.e., carboxylic ester, thiophene, and aniline moieties. Azide moieties introduced into cellulose via the tosyl derivative were simply transferred with ethynyl compounds under Cu(I) catalysis and mild and easily applicable conditions. Hydrolytically stable cellulose derivatives soluble in organic solvents, e.g., DMSO or DMF with DS up to 0.9 are obtained. The triazole substituted cellulose derivatives were characterized by elemental analysis, FTIR, 1H NMR, and 13C NMR spectroscopies and show no impurities or substructures resulting from side reactions.6‐Azido‐6‐deoxy cellulose.magnified image6‐Azido‐6‐deoxy cellulose.
Ionic Polymer‐Metal Composite Actuators Employing Radiation‐Grafted Fluoropolymers as Ion‐Exchange Membranes
Authors: Han Man Jae , Park Jong Hyuk , Lee Jang Yeol , Jho Jae Young 
Published: January 2006

AbstractSummary:To develop ionic polymer‐metal composites (IPMC) with improved performance, three new ion‐exchange membranes were prepared and employed in IPMC construction. The membranes were prepared by radiation‐grafting of polystyrene sulfonic acid onto three fluoropolymers; poly(vinylidenefluoride‐co‐hexafluoropropylene), poly(ethylene‐co‐tetrafluoroethylene), and poly(tetrafluoroethylene‐co‐hexafluoropropylene). The bending displacements of the IPMCs constructed with these membranes were at least several times larger than that of Nafion IPMC of similar thickness without straightening‐back. The larger displacement was considered to be due to the higher concentration of ionic groups and consequent larger ion‐exchange capacity.Actuation of (a) Nafion IPMC and (b) IPMC prepared in this study.magnified imageActuation of (a) Nafion IPMC and (b) IPMC prepared in this study.
New Strategy for Enzymatic Synthesis of High‐Molecular‐Weight Poly(butylene succinate) via Cyclic Oligomers
Authors: Sugihara Satoko , Toshima Kazunobu , Matsumura Shuichi 
Published: January 2006

AbstractSummary: High‐molecular‐weight poly(butylene succinate) (PBS) is prepared by the lipase‐catalyzed polymerization of dimethyl succinate and butane‐1,4‐diol via the formation of cyclic oligomers as a new strategy for the green production of bio‐based plastics. The cyclic oligomer is first produced by the lipase‐catalyzed condensation of dimethyl succinate and butane‐1,4‐diol in a dilute toluene solution using lipase from Candida antarctica, followed by the ring‐opening polymerization of the cyclic oligomer in a more concentrated solution or in bulk with the same lipase to produce PBS with an of 130 000. On the other hand, PBS is produced with an of 45 000 by direct polycondensation.The lipase‐catalyzed preparation of PBS by two routes.magnified imageThe lipase‐catalyzed preparation of PBS by two routes.
Protein nanoarray on Prolinker™ surface constructed by atomic force microscopy dip‐pen nanolithography for analysis of protein interaction
Authors: Lee Minsu , Kang Dong‐Ku , Yang Hyun‐Kyu , Park Keun‐Hyung , Choe Soo Young , Kang ChangSoo , Chang Soo‐Ik , Han Moon Hi , Kang In‐Cheol 
Published: January 2006

AbstractProtein nanoarrays are addressable ensembles of nano‐scale protein domain on solid surfaces. This method can serve as a useful platform for ultraminiaturized bioanalysis. In this study, we investigated single molecular nanopatterning and molecular interaction of proteins that were immobilized on Prolinker™ surface of gold‐coated silicon wafer by using dip‐pen nanolithography (DPN) method. Contact force and humidity were optimized at 0.01 nN and 80%, respectively. The domain features of protein nanoarrays were developed at the contact time of 5 s. The optimized conditions for the nanoarray process were applied to create protein nanoarray using integrin αvβ3 and angiogenin. Constructed protein nanoarrays using integrin αvβ3 have single molecular monolayer with regular domain shape (height 15 ± 5 nm). The changed height value due to the single molecular interaction between integrin αvβ3 and vitronectin was approximately 30 ± 5 nm on Prolinker™ surface as measured with atomic force microscopy tip. Taken together, these results suggest that protein nanoarray on Prolinker™ surface fabricated by well‐controlled DPN process can be used to analyze single molecular interaction of protein.
On the nature of the CP group adjacent to a valence‐deficient atom: phosphaethynyl substituent vs. phosphorus center
Authors: Pham‐Tran Nguyen‐Nguyen , Hou Xin Juan , Nguyen Minh Tho 
Published: January 2006

AbstractOn the basis of quantum chemical calculations (CCSD(T), CASSCF and B3LYP), we have demonstrated in this work that the CP group, when connected to a valence‐deficient center, in particular in a triplet state or a radical, its π‐electrons tend to move into other parts of the system, thus transforming the formal RCP system into a P‐centered RCP species. The CP group does not behave as a phosphaethynyl substituent, but rather as a P‐centered phosphinidene or a P‐radical. Copyright © 2006 John Wiley & Sons, Ltd.
The determinants of stability in the human prion protein: Insights into folding and misfolding from the analysis of the change in the stabilization energy distribution in different conditions
Authors: Colacino Stefano , Tiana Guido , Broglia Ricardo A. , Colombo Giorgio 
Published: January 2006

AbstractThe dynamic evolution of the PrPC from its NMR‐derived conformation to a β‐sheet‐rich, aggregation‐prone conformation is studied through all‐atom, explicit solvent molecular dynamics in different temperature and pH conditions. The trajectories are analyzed by means of a recently introduced energy decomposition approach aimed at identifying the key residues for the stabilization and folding of the protein. It is shown that under native conditions the stabilization energy is concentrated in regions of the helices H1 and H3, whereas under misfolding conditions (low pH, high temperature, or mutations in selected sites) it is spread out over helix H2. Misfolding appears to be a rearrangement of the chain that disrupts most of the native secondary structure of the protein, producing some β‐rich conformations with an energy distribution similar to that of the native state. Proteins 2006. © 2005 Wiley‐Liss, Inc.
Deduction of functional peptide motifs in scorpion toxins
Authors: Tan Paul T. J. , Ranganathan Shoba , Brusic Vladimir 
Published: January 2006

AbstractScorpion toxins are important physiological probes for characterizing ion channels. Molecular databases have limited functional annotation of scorpion toxins. Their function can be inferred by searching for conserved motifs in sequence signature databases that are derived statistically but are not necessarily biologically relevant. Mutation studies provide biological information on residues and positions important for structure–function relationship but are not normally used for extraction of binding motifs. 3D structure analyses also aid in the extraction of peptide motifs in which non‐contiguous residues are clustered spatially. Here we present new, functionally relevant peptide motifs for ion channels, derived from the analyses of scorpion toxin native and mutant peptides. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd.
Results of L‐[1‐13C]phenylalanine breath test with air isotope ratio mass spectrometry can reflect the activity of phenylalanine hydroxylase in cirrhotic rat liver
Authors: Yan Weili , Xiong Ping , Liu Zhengwei , Huang Gang 
Published: January 2006

AbstractThe L‐[1‐13C]phenylalanine breath test (PheBT) could potentially advance the evaluation of hepatocyte function and liver functional reserve. However, because the factors influencing PheBT results have not been clarified, the clinical application of the test has been limited. This study investigated the relationship between the parameters of PheBT, performed with air isotope ratio mass spectrometry, and the activity of phenylalanine hydroxylase (PAH), the phenylalanine metabolism rate‐limiting enzyme, in rat liver, and proposes valid parameters for the assessment of liver function. Chronic injury to the liver was induced by the administration of CCl4 to male Sprague‐Dawley rats for either 8 or 12 weeks. Livers from rats in the two cirrhotic groups were discolored, enlarged and roughly textured, with cells filled with fat granules of various sizes, pseudolobuli formations, and regenerated tubercles. Of the 12 parameters tested, only the unit liver weight (LW) breath test parameters, including the maximum abundance of 13C in breath (13Cmax/LW), 13C abundance in breaths 2 and 7 min after administration of L‐[1‐13C]phenylalanine (13C‐phe) (13C2/LW and 13C7/LW), cumulative 13C excretion 10 and 30 min after 13C‐phe administration (AUC10/LW and AUC30/LW), and the 13C excretion rate constant (PheBT‐k/LW) were significantly affected in the chronic liver injury groups. There was no significant difference in the total PAH activity in liver among the three groups, but there was significant difference in unit LW PAH activity. Total PAH activity in the liver was significantly correlated with 13Cmax, 13C2, 13C7, AUC10, AUC30 and PheBT‐k, while the unit LW PAH activity was significantly correlated with 13Cmax/LW, 13C2/LW, 13C7/LW, AUC10/LW, AUC30/LW and PheBT‐k/LW. PheBT‐k/LW was also correlated with biochemical indices that are used to assess liver function. The present findings indicate that the PheBT results based on air isotope ratio mass spectrometry can quantitatively reflect the change in total PAH activity in the livers of chronically injured rats. PheBT‐k and PheBT‐k/LW are the most sensitive among the test parameters, and can be used to assess liver functional reserve and hepatocyte damage at the molecular level. Copyright © 2006 John Wiley & Sons, Ltd.
Characterization of unusual alkenones and alkyl alkenoates by electron ionization gas chromatography/mass spectrometry
Authors: Rontani J.‐F. , Prahl F. G. , Volkman J. K. 
Published: January 2006

AbstractUnusual long‐chain, diunsaturated alkenones and alkyl alkenoates exhibiting double bonds separated by three methylene units instead of the more usual five were characterized by electron ionization (EI) gas chromatography/mass spectrometry. In a first step, the positions of the double bonds of these compounds (isolated from Holocene Black Sea sediments) were confirmed after OsO4 treatment and silylation. Mass spectra of the resulting tetratrimethylsilyloxy derivatives allowed unambiguous determination of the positions of unsaturations. The EI mass spectra of the non‐derivatized compounds were then compared with those of the alkenones and alkyl alkenoates having double bonds separated by five methylene units. Specific fragment ions resulting from γ‐H rearrangements were found to be prominent in EI mass spectra of these unusual ‘Black Sea’ diunsaturated alkenones and alkyl alkenoates. These fragment ions can be used to characterize these compounds in natural samples without the need for laborious derivatization treatments. Copyright © 2006 John Wiley & Sons, Ltd.
Effects of chemical lipid extraction and arithmetic lipid correction on stable isotope ratios of fish tissues
Authors: Sweeting C. J. , Polunin N. V. C. , Jennings S. 
Published: January 2006

AbstractFor accurate interpretation of fish trophodynamics from carbon stable isotope data it is necessary to extract tissue lipids. This is because lipid content varies within and among tissues in both space and time, and because lipids are 13C‐depleted relative to proteins. However, lipid extraction may affect δ15N, thus requiring costly and time‐consuming separation of δ13C and δ15N analyses. These problems have prompted the development of arithmetic correction techniques for δ13C, but the techniques and their underlying assumptions have not been systematically tested. This study compared the effects of lipid extraction and arithmetic correction techniques on δ13C and δ15N of European sea bass (Dicentrarchus labrax) tissues. Following Folch lipid extraction from muscle and liver, there was a mean increase in δ15N of 0.77‰, but enrichment varied with lipid content such that effects on δ15N were hard to predict. Changes in δ13C and C:N between untreated and lipid‐extracted samples reflected the quantity of lipid removed. The arithmetic correction techniques of mass balance and lipid correction were sensitive to the C:N of the lipid‐extracted tissue and to the assumed depletion of lipid δ13C relative to protein δ13C. However, the mass balance approach was appropriate for the mathematical correction of bulk tissue data in most circumstances, provided that the C:N of lipid‐extracted tissue could be determined for a small proportion of samples. Application of mass balance arithmetic correction can lead to significant time and cost savings in trophodynamic studies, because the majority of δ13C and δ15N analyses would not need to be run separately. Copyright © 2006 John Wiley & Sons, Ltd.
Optimal filtering for polynomial system states with polynomial multiplicative noise
Authors: Basin Michael , Perez Joel , Skliar Mikhail 
Published: January 2006

AbstractIn this paper, the optimal filtering problem for polynomial system states with polynomial multiplicative noise over linear observations is treated proceeding from the general expression for the stochastic Ito differential of the optimal estimate and the error variance. As a result, the Ito differentials for the optimal estimate and error variance corresponding to the stated filtering problem are first derived. The procedure for obtaining a closed system of the filtering equations for any polynomial state with polynomial multiplicative noise over linear observations is then established, which yields the explicit closed form of the filtering equations in the particular cases of a linear state equation with linear multiplicative noise and a bilinear state equation with bilinear multiplicative noise. In the example, performance of the designed optimal filter is verified for a quadratic state with a quadratic multiplicative noise over linear observations against the optimal filter for a quadratic state with a state‐independent noise and a conventional extended Kalman–Bucy filter. Copyright © 2006 John Wiley & Sons, Ltd.
Selective attention for negative information and depression in schizophrenia
Authors: WATERS FLAVIE A. V. , BADCOCK JOHANNA C. , MAYBERY MURRAY T. 
Published: January 2006

Objectives. Depression is a frequent feature of schizophrenia but the cognitive processes involved in its development and maintenance are unclear. Recent studies have shown that clinical depression is associated with faulty inhibitory mechanisms of selective attention for negative information. The current study examined whether patients with schizophrenia also have an attentional bias towards negative stimuli. The inhibitory processes of interference control and task-shifting abilities were also examined to assess whether patients would show a selective impairment.Method. Forty-three patients with schizophrenia and 24 healthy controls completed the Affective Shifting Task.Results. As a group, schizophrenia patients did not show an attentional bias for negative material. However, those patients with high levels of depression demonstrated faster latencies when negative words were the targets, and higher depression scores were found to be associated with an increasing number of false alarms for negative words when they were not the targets. The results also showed that patients had impaired interference control but intact task-shifting abilities.Conclusions. Faulty inhibitory mechanisms of selective attention for negative information are not a general feature of schizophrenia but appear to be selective to those with a depressed mood. The results highlight the need for further studies examining the exact nature of the affective dysfunction in schizophrenia and the cognitive processes supporting negative emotions.
Investigation of the role of TASK‐2 channels in rat pulmonary arteries; pharmacological and functional studies following RNA interference procedures
Authors: Gönczi Mónika , Szentandrássy Norbert , Johnson Ian T , Heagerty Anthony M , Weston Arthur H 
Published: January 2006

In the present study, we investigated the ability of RNA interference technology to suppress TASK‐2 potassium channel expression in human embryonic kidney (HEK293) cells stably transfected with TASK‐2 cDNA and in rat isolated intact pulmonary arteries.
Lipofectamine‐induced transfection of a specific siRNA sequence targeted against TASK‐2 resulted in a dose‐ and time‐dependent decrease in TASK‐2 channel protein expression. In siRNA‐transfected cells the TASK‐2 peak currents were significantly smaller than in control cells at every investigated pH, while the pH sensitivity was not altered. Using scrambled siRNA as a negative control, there were no significant changes in TASK‐2 protein expression or current compared to mock‐transfected cells.
In TASK‐2 siRNA‐transfected small pulmonary arteries, but not in scrambled siRNA‐treated vessels, myocyte resting membrane potential at pH 7.4 was significantly less negative and the hyperpolarisations in response to increasing pH from 6.4 to 8.4 were significantly smaller compared with control.
The application of levcromakalim (10 μM), NS1619 (33 μM) and a potassium channel inhibitor cocktail (5 mM 4‐aminopyridine, 10 mM tetraethylammonium chloride, 30 μM Ba2+ and 10 μM glibenclamide) had similar effects in control and in siRNA‐transfected vessels. The TASK‐1 (anandamide‐sensitive) contribution to resting membrane potential was comparable in each group. Clofilium (100 μM) generated significantly smaller responses in transfected artery segments.
These results suggest that RNA interference techniques are effective at inhibiting TASK‐2 channel expression in cultured cells and in intact vessels and that TASK‐2 channels have a functional role in setting the membrane potential of pulmonary artery myocytes.

British Journal of Pharmacology (2006) 147, 496–505. doi:10.1038/sj.bjp.0706649
Substance P‐induced cyclooxygenase‐2 expression in human umbilical vein endothelial cells
Authors: Gallicchio Margherita , Rosa Arianna Carolina , Benetti Elisa , Collino Massimo , Dianzani Chiara , Fantozzi Roberto 
Published: January 2006

Substance P (SP) is a neuropeptide involved in neurogenic inflammation and an agonist for NK1, NK2, and NK3 receptors. SP induces prostaglandin (PG) production in various cell types, and these eicosanoids are responsible for numerous inflammatory and vascular effects.
Cyclooxygenase (COX) are needed to convert arachidonic acid to PGs. The study evaluated the effect of SP on COX expression in human umbilical vein endothelial cells (HUVEC).
COX‐2 protein expression was upregulated by SP with a peak at 100 nM and at 20 h; in the same experimental conditions COX‐1 protein expression was unchanged. A correlation between COX‐2 expression and PGI2 and PGE2 release was detected.
Dexamethasone (DEX) inhibited SP‐mediated COX‐2 expression. Mitogen‐activated protein kinases (MAPK) p38 and p42/44 were activated by SP, whereas SB202190 and PD98059, inhibitors of these kinases, blocked COX‐2 expression. 5,5‐dimethyl‐3‐(3‐fluorophenyl)‐4‐(4‐methylsulphonyl)phenyl‐2(5H)‐furanone (DFU), an experimental selective COX‐2 inhibitor, blocked SP‐induced PG release.
By RT–PCR and Western blot analysis, we demonstrated that NK1 and NK2 but not NK3 receptors are present on HUVEC. Selective NK1 and NK2 agonists, namely [Sar9, Met(O2)11]SP and [β‐Ala8] NKA(4–10), upregulated COX‐2 protein expression and PG production, whereas senktide (Suc–Asp–Phe–MePhe–Gly–Leu–Met–NH2), a selective NK3 agonist, was ineffective in this respect. The NK1 selective antagonist L703,606 ((cis)‐2‐(diphenylmethyl)‐N‐((2‐iodophenyl)‐methyl)‐1‐azabicyclo(2.2.2)octan‐3‐amine) and the NK2 selective antagonist SR 48,968 ((S)‐N‐methyl‐N‐(4‐(4‐acetylamino‐4‐phenylpiperidino)‐2‐(3,4 dichlorophenyl)butyl) benzamide) competitively antagonised SP‐induced effects.
The study shows HUVEC to possess functional NK1 and NK2 receptors, which mediate the ability of SP to induce expression of COX‐2 in HUVEC, thus showing a previously‐undetected effect of SP on endothelial cells.

British Journal of Pharmacology (2006) 147, 681–689. doi:10.1038/sj.bjp.0706660