bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fuscopeptins, antimicrobial lipodepsipeptides from Pseudomonas fuscovaginae, are channel forming peptides active on biological and model membranes
Authors: Coraiola M. , Paletti R. , Fiore A. , Fogliano V. , Serra M. Dalla 
Published: December 2007

AbstractFP‐A and FP‐B are LDPs produced by the plant pathogen Pseudomonas fuscovaginae. As expected from their primary structure, they shared a similar mechanism of action with the better characterized SPs, synthesized by strains of Pseudomonas syringae pv. syringae. Indeed, they displayed hemolytic activity on human erythrocytes and were able to induce calcein release from LUVs: the effect was dependent on the concentration of the FPs and the lipid composition of the liposome and, in particular, it increased with the SM content of the membrane. The permeabilizing activity was further investigated on PLMs. FPs were able to open pores on pure POPC membranes. Pore opening was strongly voltage dependent: by switching the potential from negative to positive values, an increase in the absolute amplitude of transmembrane current was induced with simultaneous closure of pores. In 0.1 M KCl both FPs' pores had a conductance of 4 and 9 pS at − 140 mV and + 140 mV, respectively. Studies on ion selectivity indicated that FPs formed cation‐selective channels. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
Solid‐phase synthesis of tailed cyclic RGD peptides using glutamic acid: unexpected glutarimide formation
Authors: Zhu Junmin , Marchant Roger E. 
Published: December 2007

AbstractTo provide multiple conjugating sites on cyclic peptides for their increasing biomedical applications, a tailed cyclic RGD peptide, c[RGDfE(GGGKK‐NH2)] was designed with c(RGDfE) linked through Glu to a tail consisting of a spacer of three Gly residues and a linker of two Lys residues. The spacer is used to increase the mobility and binding ability of the c(RGDfE) ligand, and the linker is used to proved multiple active sites for conjugating other molecules or biomaterials. We found that the sequence of Glu(Gly)‐OAll leads to glutarimide formation, which disrupts the formation of cyclic RGD peptides. However, our results show that glutarimide formation is sequence dependent and can be inhibited by incorporating an amino acid like Lys(Boc) with steric hindrance from the protecting group. To prevent glutarimide formation, Ser(tBu) was used to replace the glycine in the GGG spacer adjacent to the residue of Glu, and a tailed cyclic RGD peptide, c[RGDfE(SGGKK‐NH2)] was successfully obtained. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
Structuring and interactions of human β‐defensins 2 and 3 with model membranes
Authors: Morgera Francesca , Antcheva Nikolinka , Pacor Sabrina , Quaroni Luca , Berti Federico , Vaccari Lisa , Tossi Alessandro 
Published: December 2007

Abstractβ‐Defensins play an important role in both innate and adaptive immunity, displaying a direct anti‐microbial activity against a wide variety of micro‐organisms as well as interesting immuno‐modulatory effects on host cells. Interaction with biological membranes appears to be a central theme in modulating these activities, leading to different consequences such as membrane lysis, translocation into the cytoplasm or transfer to a receptor. We have investigated the structuring of human β‐defensins (hBD2 and hBD3) and rationally designed variants, in relation to their interactions with real and model membranes. Biophysical methods, such as circular dichroism (CD), transmission or reflection IR and dye release were used to probe their structure/activity in the presence of model membranes, while fluorimetric and flow cytometric assays were used to investigate the effects on prokaryotic cells. Our results indicate that structural features, such as the helical N‐terminal domains and oligomerisation at the membrane surface, may modulate the efficiency of membrane insertion and selectivity for microbial or host‐cell membranes. We propose that both peptides interact with membranes as extended β‐sheet platforms that present amphipathic helices for insertion into the lipid bilayer. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
Thermal and electrical transport properties of a single nickel nanowire
Authors: Ou M. N. , Harutyunyan S. R. , Lai S. J. , Chen C. D. , Yang T. J. , Chen Y. Y. 
Published: December 2007

AbstractThe thermal conductivity (κ), specific heat (Cp) and the resistivity (ρ) of a single nickel nanowire have been measured in the temperature range from 4 to 300 K by means of the “self heating 3ω” technique. Starting with a 100 nm nickel film grown on a Si/Si3N4 substrate by thermal evaporation, a suspended nickel nanowire was then fabricated through e‐beam lithography and etching processes. The width and length of the wire were determined by scanning electron microscope (SEM) as 180 nm and 35 μm re‐spectively. At 300 K the thermal conductivity of nanowire is ∼ 20% of the bulk, it diminishes to lower value as temperature decreases. The consequence is opposite to that of the bulk and might be explained by the ristriction of mean free paths of electron/phonon–phonon interactions due to the grain boundaries. An enhancement of specific heat ∼250% of the bulk is also observed. In addition, the resistivity of nanowire at room temperature is about four times larger than that of the bulk. The small relative resistiv‐ity ratio (RRR) confirms the polycrystalline characteristic of the nanowire. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Vortex dynamics in submicron exchange‐biased disks
Authors: Moon Jung Hwan , Kim Woo Jin , Lee Taek Dong , Lee Kyung‐Jin 
Published: December 2007

AbstractUsing micromagnetic simulation we have investigated the vortex dynamics in an exchange‐biased permalloy nanodisk with 500 nm‐radius and 10 nm‐thickness. We found the exchange bias plays an important role in the vortex dynamics. The exchange bias results in the elliptical trajectory. The vortex dynamics in the exchange‐biased nanodisk is strongly affected by the angle between the exchange bias field and the external field. We found that it is possible to selectively transform the vortex state into the single domain state with a pulsed magnetic field by controlling the magnitude and the angle of the external magnetic field. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of aspect ratio of nanostrip on transformation of transverse domain wall due to adiabatic spin torque
Authors: Seo S. M. , Kim W. J. , Lee T. D. , Lee K. J. 
Published: December 2007

AbstractWe have studied the current‐induced dynamics of the transverse domain wall in the adiabatic limit. Above the threshold current density for the continuous domain wall motion, the transverse wall is transformed by the injection of the antivortex. In general, the wall velocity increases and the wall width decreases as the antivortex is injected. However, detailed time‐dependent profiles of the wall velocity and the wall width are significantly affected by the aspect ratio of the nanostrip. The mean velocity of the TW decreases as the aspect ratio increases. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Inhomogeneous surface electronic properties and charge ordering in epitaxial Fe3O4 films on MgO(001)
Authors: Subagyo A. , Sasaki Y. , Oka H. , Sueoka K. 
Published: December 2007

AbstractWe report scanning tunneling microscopy (STM) study of surface electronic properties and charge ordering of epitaxially grown magnetite, Fe3O4, (001) films exhibiting high density of antiphase domain boundaries (APBs). STM measurements using a W tip reveal surface termination at B‐sites. Fe ions with a 0.3 nm periodicity, i.e., a single atomic distance are observed. Current imaging tunneling spectroscopy reveals the alternation of two kinds of current peaks with a 0.6 nm periodicty indicating the presence of charge ordering consisted of Fe dimers with different charge states. STM measurements using a magnetic Ni tip provide higher contrast of the charge ordering. The APBs can modify the charge ordering as ordered and disordered areas are observed on adjacent domains separated by an APB. These strongly indicate that APBs can induce inhomogeneous properties on the surface of Fe3O4(001) films. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Half metallic ferromagnetism of Mn doped AlSb: A first principles study
Authors: Rahman Gul. , Cho Sungle , Hong Soon Cheol 
Published: December 2007

AbstractWe employ the spin‐polarized, full potential linearized augmented plane wave (FLAPW) method within generalized gradient approximation (GGA) to study the electriconic and magnetic properties of Al1–xMnxSb (x = 0.25, 0.50, 0.75, and 1.0). We find that Al1–xMnxSb is a half metal ferromagnet. The Fermi level shifts toward high energy with the increase of Mn concentration. At the end composition (i.e. MnSb) the Fermi level touches the conduction band edge and MnSb is nearly a half met al. The minority spin gap (∼1.0 eV) is robust to the change of Mn concentration. The total magnetic moment per Mn of Al1–xMnxSb is also (4.0 µB) independent of the Mn concentration due to its half‐metallicity. The induced magnetic polarization of the nearest Sb atom is antiparallel to that of Mn atom whereas parallel magnetic polarization is found at the Al site. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ferromagnetic resonance spectra in patterned and unpatterned NiFe/Pt films
Authors: Ando K. , Sasage K. , Harii K. , Saitoh E. 
Published: December 2007

AbstractThe ferromagnetic resonance in nanostructured Ni81Fe19 films comprising flim parts and wire parts covered with Pt has been investigated. In contrast to the systematic variation of the FMR linewidth for the film parts, the linewidth for the nanostructured wire parts shows an irregular change with changing the thickness of Pt. This irregular change indicates that the spin current absorption in the Pt layer cannot fully account for the linewidth change in the wire parts. This FMR‐linewidth variation can be argued in terms of the competition between the spin pumping and the roughness effect. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spin accumulation from the spin Hall effect and the anisotropic effect studied using the effective mean‐free‐path model
Authors: Chen S.‐P. , Chang C.‐R. 
Published: December 2007

AbstractA thin film system with the spin Hall effect and the anisotropic effect is investigated by use of the effective mean‐free‐path model. Its spin accumulation from the spin Hall effect is supressed by the the anisotropic effect. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microstructure and magnetic properties of Fe/X (X = Au, Ag, Cu) multilayer films grown on MgO(001) substrates
Authors: Ohtake Mitsuru , Yasui Yusuke , Kirino Fumiyoshi , Futamoto Masaaki 
Published: December 2007

AbstractFe/X (X = Au, Ag, Cu) epitaxial multilayer films were prepared on MgO(001) substrates at a substrate temperature of 300 °C by alternate deposition of Fe and X atomic layers. The composition of Fe/X multilayer was varied from the ratio around the L 10 phase stoichiometry (Fe:X = 50:50) to X ‐rich region. The effects of X atom on the microstructure, magnetic properties, and formation of L 10 ordered phase were investigated. X‐ray analysis has shown that L 10 ordered phase is formed in the Fe/Au system and that a stronger intensity of L 10 phase is observed in an Au‐rich compositional region. No evidence of L 10 ordered phase formation is recognized for the Fe/Ag and the Fe/Cu systems. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Room‐temperature magnetic entropy change in La0.7Sr0.3Mn1‐xMxO3 (M = Al, Ti)
Authors: Dai N. V. , Son D. V. , Yu S. C. , Bau L. V. , Hong L. V. , Phuc N. X. , Nam D. N. H. 
Published: December 2007

AbstractMagnetic entropy change in and above the room‐temperature region has been measured for La0.7Sr0.3Mn1‐x Mx O3 (M = Al, Ti) by means of magnetization measurements in magnetic fields up to 6 T. The magnetocaloric effect (MCE) becomes strongest at the Curie temperature Tc that is tuned to ∼300 K by the substitution of Al or Ti for Mn. While the substitution of Al for Mn drastically reduces the entropy change, it extends considerably the working temperature span and improves the relative cooling power (RCP). The MCE and RCP seem to be only lightly affected by Ti substitution. Although manganites are considered potential for magnetic refrigerants, the limitations for achieving strong MCE in the materials are also discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of A‐site ionic size variation on the magnetic and transport properties of (PrxSm1–x)2/3Sr1/3MnO3 (0 ≤ x ≤ 1)
Authors: Asthana Saket , Dho Joonghoe , Bahadur D. 
Published: December 2007

AbstractThe effects of average A‐site ionic size on magnetic and transport properties have been studied in (PrxSm1–x)2/3Sr1/3MnO3 (0 ≤ x ≤ 1) manganites with fixed carrier concentration. An effect of average A‐site ionic radius (<rA>) with the Pr substitution has been clearly observed in the continuous changes of ferromagnetic transition temperature and metal–insulator transition temperature. The change of the resistivity with the x was explained by a variation in the hopping integral between Mn3+ and Mn4+, which is dependent on the Mn‐O‐Mn bond angle affected by the average A‐site ionic size. Remarkably, the Sm‐doped manganites showed an antiferromagnetic transition by the rare‐earth moments below 50 K as well as the ferromagnetic transition by Mn moments at a higher temperature. A phase diagram of (PrxSm1–x)2/3Sr1/3MnO3 (0 ≤ x ≤ 1) was successfully constructed on the basis of magnetic and transport studies. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of Zn0.5(Ni,Co)0.5Fe2O4 mixed spinel ferrite thin films
Authors: Mathe T. G. , Moyo T. , Msomi J. Z. 
Published: December 2007

AbstractMixed spinel ferrites Zn0.5Co0.5Fe2O4 (Zn‐Co) and Zn0.5Ni0.5Fe2O4 (Zn‐Ni) thin films were prepared on silicon (100) substrates by pulsed laser deposition (PLD) technique, operating at 248 nm. Single phase formation of spinel structure was confirmed by X‐Ray Diffraction (XRD). Optical measurements were obtained by Fourier Transform InfraRed (FTIR) spectroscopy. Optical absorption spectra at room temperature (RT) show broad absorption bands. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Extraction of device parameters from dark current‐voltage characteristics of PV devices
Authors: Macabebe Erees Q. B. , van Dyk E. Ernest 
Published: December 2007

AbstractSolar cells are p‐n junction diodes and are prone to parasitic resistances. High series resistances of a few ohms degrade the device performance, as do low shunt resistances. It is therefore necessary to determine these parameters since they are useful in analyzing performance losses. A method to extract these and other device parameters of solar cells from the dark current‐voltage (I‐V) characteristics is presented in this paper. The following parameters were determined using the proposed method: saturation current, series resistance, shunt resistance and the ideality factor. A program was created to implement the method which utilized the one‐diode equivalent circuit model. Curve‐fitting was also employed to provide a graphical representation of the results. Evaluation of the method was done using simulated data and actual dark I‐V data obtained from monocrystalline and multicrystalline silicon solar cells. The program algorithm is discussed and results are presented. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Monte Carlo reliability model for microwave monolithic integrated circuits
Authors: Christou Aris 
Published: December 2007

AbstractA Monte Carlo simulation is reported for analog integrated circuits and is based on the modification of the failure rate of each component due to interaction effects of the failed components. The Monte Carlo technique is the methodology used to treat such circuits, since they are independent of the number of components and the degree of system complexity. The reliability model is applicable over a wide temperature and bias range and may be used to predict reliability of microwave systems. The model is compared with accelerated test results of two analog microwave circuits. Excellent agreement has been obtained for a low noise amplifier as well as for a transimpedence amplifier. Copyright © 2007 John Wiley & Sons, Ltd.
High‐performance liquid chromatography/electrospray ionization tandem mass spectrometry for characterization of enzymatic degradation of 2,2′‐bis(2‐oxazoline)‐linked poly‐ε‐caprolactone
Authors: Pulkkinen Mika , Palmgrén Joni J. , Auriola Seppo , Malin Minna , Seppälä Jukka , Järvinen Kristiina 
Published: December 2007

AbstractThis paper describes a straightforward and rapid on‐line characterization using high‐performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ESI‐MSn) of the enzymatic degradation products of 2,2′‐bis(2‐oxazoline)‐linked poly‐ε‐caprolactone (PCL‐O). These new PCL‐O polymers are expected to be used in a variety of pharmaceutical and biomedical applications since they are degraded enzymatically by surface erosion. PCL‐O was polymerized in a three‐step reaction and characterized by 1H‐NMR and size‐exclusion chromatography (SEC). Solvent cast polymer films were exposed to enzymatic degradation in phosphate buffer (pH 7.5, 1% pancreatin). The enzymatic degradation of the polymer produced a wide variety of water‐soluble oligomers which were separated and identified by HPLC/ESI‐MSn. Optimization of the gradient HPLC method resulted in effective separation of the oligomers. Furthermore, specific structures of the oligomers were clearly identified by tandem mass spectrometry. According to these results, ester bonds seem to be most sensitive to enzymatic degradation and, correspondingly, pancreatic lipase seems to be mainly responsible for the enzymatic erosion of the PCL‐O films. This novel mass spectrometric method provides important knowledge about the enzymatic degradation process and structure of the polymer which is difficult to ascertain by other conventional methods. Copyright © 2007 John Wiley & Sons, Ltd.
The N‐domain of angiotensin‐converting enzyme specifically hydrolyzes the Arg‐5‐His‐6 bond of Alzheimer's Aβ‐(1‐16) peptide and its isoAsp‐7 analogue with different efficiency as evidenced by quantitative matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Authors: Toropygin Ilya Yu. , Kugaevskaya Elena V. , Mirgorodskaya Olga A. , Elisseeva Yulia E. , Kozmin Yuri P. , Popov Igor A. , Nikolaev Eugene N. , Makarov Alexander A. , Kozin Sergey A. 
Published: December 2007

AbstractChronic imbalance between production and degradation of the human amyloid‐beta peptide (Aβ) is assumed to play an important role in pathogenesis of Alzheimer's disease (AD). Post‐translational modifications of Aβ could influence its interactions with specifically cleaving proteases and, therefore, perturb the Aβ homeostasis. The angiotensin‐converting enzyme (ACE) was previously shown to degrade non‐modified Aβ in vitro and in cells. In the presented work, we investigated the effect of isomerization of Asp‐7, a common non‐enzymatic age‐related modification found in AD‐associated Aβ species, on hydrolysis of Aβ by ACE. Two synthetic peptides corresponding to the Aβ region 1‐16 with either Asp or isoAsp residues in position 7 were examined as monomeric soluble substrates for the N‐ as well as for the C‐domain of ACE. The use of matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS) coupled with the 18O‐labeled internal standard approach has allowed us to show that (i) the N‐domain of ACE (N‐ACE), but not the C‐domain, selectively cleaves the Arg‐5‐His‐6 bond in both peptides, and that (ii) N‐ACE hydrolyzes the isoAsp‐7 analogue more efficiently than the non‐modified one. Our results demonstrate a new endopeptidase activity of N‐ACE as well as high preference of the domain to recognize and hydrolyze the isomerized Aβ species that were earlier suggested to promote AD pathogenesis. The results suggest the need for further analysis of biological effects of isomerized Aβ and its interaction with ACE in AD pathogenesis. Copyright © 2007 John Wiley & Sons, Ltd.
Measurement error in the explanatory variable of a binary regression: Regression calibration and integrated conditional likelihood in studies of residential radon and lung cancer
Authors: Fearn T. , Hill D. C. , Darby S. C. 
Published: December 2007

AbstractIn epidemiology, one approach to investigating the dependence of disease risk on an explanatory variable in the presence of several confounding variables is by fitting a binary regression using a conditional likelihood, thus eliminating the nuisance parameters. When the explanatory variable is measured with error, the estimated regression coefficient is biased usually towards zero. Motivated by the need to correct for this bias in analyses that combine data from a number of case–control studies of lung cancer risk associated with exposure to residential radon, two approaches are investigated. Both employ the conditional distribution of the true explanatory variable given the measured one. The method of regression calibration uses the expected value of the true given measured variable as the covariate. The second approach integrates the conditional likelihood numerically by sampling from the distribution of the true given measured explanatory variable. The two approaches give very similar point estimates and confidence intervals not only for the motivating example but also for an artificial data set with known properties. These results and some further simulations that demonstrate correct coverage for the confidence intervals suggest that for studies of residential radon and lung cancer the regression calibration approach will perform very well, so that nothing more sophisticated is needed to correct for measurement error. Copyright © 2007 John Wiley & Sons, Ltd.
Intranasal dopamine application increases dopaminergic activity in the neostriatum and nucleus accumbens and enhances motor activity in the open field
Authors: De Souza Silva M.A. , Topic B. , Huston J.P. , Mattern C. 
Published: December 2007

AbstractDopamine (DA) plays an important role in a number of behavioral processes and neurological disorders. The intranasal administration of DA provides improved brain penetrability in comparison to systemic administration. We investigated the effects of intranasal administration of DA on the activity of dopaminergic neurons of the mesostriatal and mesolimbic systems and on motor activity. Rats previously implanted with guide‐cannulae in the neostriatum (NS) and nucleus accumbens (NAc) were submitted to microdialysis procedure under urethane anesthesia. Vehicle or DA (0.03, 0.3, or 3.0 mg/kg) was administered bilaterally into the nostrils. In a separate study, animals received an intraperitoneal (i.p.) injection of vehicle or DA (0.03, 0.3, 3.0, or 30.0 mg/kg). Samples were collected every 10 min and analyzed for the content of DA and metabolites using high‐performance liquid chromatography. For the open field study, rats were given intranasal vehicle or DA (0.03, 0.3, or 3.0 mg/kg) and placed into the field for 30 min. Motor activity (locomotion and rearing) and grooming were analyzed in blocks of 10 min using Ethovision. Intranasal DA (3.0 mg/kg) significantly increased DA levels in the NS and NAc immediately after administration. A comparable effect was obtained only after i.p. administration of 30 mg/kg DA. In the open field, the 3.0 mg/kg dose significantly decreased grooming behavior in the second 10 min interval and significantly increased locomotor activity in the third 10 min interval. The data indicate that intranasal administration of DA can influence dopaminergic functions and motor activity, and has a potential application in the therapy of diseases affecting the dopaminergic system. Synapse 62:176–184, 2008. © 2007 Wiley‐Liss, Inc.