bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bending Energetics of Tablet‐Shaped Micelles: A Novel Approach to Rationalize Micellar Systems
Authors: Bergström L. Magnus 
Published: February 2007

AbstractA novel approach to rationalize micellar systems is expounded in which the structural behavior of tablet‐shaped micelles is theoretically investigated as a function of the three bending elasticity constants: spontaneous curvature (H0), bending rigidity (kc), and saddle‐splay constant (k̄c). As a result, experimentally accessible micellar properties, such as aggregation number, length‐to‐width ratio, and polydispersity, may be related to the different bending elasticity constants. It is demonstrated that discrete micelles or connected cylinders form when H0>1/4ξ, where ξ is the thickness of a surfactant monolayer, whereas various bilayer structures are expected to predominate when H0<1/4ξ. Our theory predicts, in agreement with experiments, a transition from discrete globular (tablet‐shaped) micelles to a phase of ordered, or disordered, connected cylinders above a critical surfactant concentration. Moreover, a novel explanation for the mechanism of growth, from small globular to long rodlike or wormlike micelles, follows as a consequence from the theory. In accordance, polydisperse elongated micelles (large length‐to‐width ratio) form as the bending rigidity is lowered, approaching the critical point at kc=0, whereas monodisperse globular micelles (small length‐to‐width ratio) are expected to be present at large kc values. The spontaneous curvature mainly determines the width of tablet‐shaped or ribbonlike micelles, or the radius of disklike micelles, whereas the saddle‐splay constant primarily influences the size but not the shape of the micelles.
Photoacoustic studies on optical and thermal properties of p‐type and n‐type nanostructured porous silicon for (100) and (111) orientations
Authors: Srinivasan R. , Jayachandran M. , Ramachandran K. 
Published: February 2007

AbstractNanostructured p‐type and n‐type porous silicon samples were prepared for (100) and (111) orientations and a systematic study is carried out on the effects of orientations, dopant type (boron and phosphorous), current density (20 and 30mA/cm2) and etching time on the formation, optical and thermal properties by photoacoustic spectroscopy. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties of thermally evaporated CdS thin films
Authors: Sahay P. P. , Nath R. K. , Tewari S. 
Published: February 2007

AbstractCdS thin films of varying thicknesses were deposited on cleaned glass substrates at room temperature by thermal evaporation technique in a vacuum of about 2 x 10‐5 torr. UV‐VIS spectra of the films were studied using the optical transmittance measurements which were taken in the spectral region from 300 nm to 1100 nm. The absorbance and reflectance spectra of the films in the UV‐VIS region were also studied. Optical constants such as optical band gap, extinction coefficient, refractive index, optical conductivity and complex dielectric constant were evaluated from these spectra. All the films were found to exhibit high transmittance (∼ 60 ‐ 93 %), low absorbance and low reflectance in the visible/near infrared region from ∼ 500 nm to 1100 nm. The optical band gap energy was found to be in the range 2.28 – 2.53 eV. All the films annealed at 300°C for 4 hours in vacuum (∼ 10‐2 torr) showed a decrease in the optical transmittance with its absorption edge shifted towards the longer wavelength, leading to the result that the optical band gap decreases on annealing the films. Also, on annealing crystallinity of the films improves, resulting in decrease in the optical transmittance. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of thermoannealing on crystallinity and optical properties of Sb2S3 thin films
Authors: Tigau N. 
Published: February 2007

AbstractSb2S3 thin films are obtained by evaporating of Sb2S3 powder onto glass substrates maintained at room temperature under pressure of 2×10‐5 torr. The composition of the thin films was determined by energy dispersive analysis of X‐ray (EDAX). The effect of thermal annealing in vacuum on the structural properties was studied using X‐ray diffraction (XRD) technique and scanning electron microscopy (SEM). The as‐deposition films were amorphous, while the annealed films have an orthorhombic polycrystalline structure. The optical constants of as‐deposited and annealed Sb2S3 thin films were obtained from the analysis of the experimental recorded transmission spectral data over the wavelength range 400‐1400 nm. The transmittance analysis allowed the determination of refractive index as function of wavelength. It was found that the refractive dispersion data obeyed the single oscillator model, from which the dispersion parameters (oscillator energy, E0, dispersion energy, Ed) were determined. The static refractive index n(0), static dielectric constant, ε∞, and optical band gap energy, Eg, were also calculated using the values of dispersion parameters. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of Direct‐Current Microdischarges for Application in Electro‐Thermal Class of Small Satellite Propulsion Devices
Authors: Kothnur P. S. , Raja L. L. 
Published: February 2007

AbstractMicrodischarges are miniature non‐equilibrium plasma discharges with characteristic dimensions of ∼10's–100's μm and relatively high operating pressures of ∼10's–100's Torr. Microdischarges possess several unique properties that have been exploited in a number of new applications. We have recently proposed amicrodischargebased electro‐thermal class of microthrusters for small satellite propulsion. These devices utilize intense gas heating in microdischarges to preheat a propellant gas stream before it is expanded in a micronozzle to produce thrust; thereby improving specific impulse of the device over a conventional cold gas microthruster. This paper addresses direct‐current microdischarge phenomena in a flowing gas stream. A two‐dimensional, selfconsistent, fluid model of a helium microdischarge in a bulk gas flow is developed. For relatively high current/power levels considered in this study, the microdischarge operates in an abnormal glow mode with positive differential resistivity. Increasing discharge pressures for fixed power and bulk flow rates results in a decrease in charged species densities and the electron and gas temperatures. Also the discharge becomes increasingly constricted with increasing pressures, resulting in a more normal glow mode‐like operation. Increasing bulk flow rates results in exactly the same trends as increasing pressures. For given input power and pressure, there exists an optimum flow rate for which the average outlet gas temperature from the discharge is a maximum. An increase in input electrical power results in an almost linear increase in the gas temperatures; this property of microdischarges is the key feature that is exploited in our microdischarge‐based thruster concept. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microplasma‐Based Treatment of Inner Surfaces in Microfluidic Devices
Authors: Klages C.‐P. , Berger C. , Eichler M. , Thomas M. 
Published: February 2007

AbstractThe paper presents one example of the utilization of microplasmas formed in cavities, which are surrounded partially or completely by dielectric materials, for surface technological processes. The modification or coating of inner surfaces in already sealed polymer‐ or glass‐based microfluidic systems is a challenging new application of atmospheric‐pressure microplasmas which promises the achievement of a wide range of physico‐chemical surface properties which are difficult to attain by wet‐chemical or low‐pressure plasma processes. Depending on the type of gas atmosphere or precursor fed into the microfluidic system, hydrophilic or hydrophobic, anionic or cationic, reactive or inert surfaces will be accessible in cost‐efficient processes. After an introduction into recent developments in the area of surface functionalization by atmospheric‐pressure dielectric barrier discharges and microplasmas, this contribution will describe the coating of inner surfaces of microfluidic devices and the evaluation of film thickness profiles along microfluidic channels using FTIR microspectroscopy. Results of thickness profile measurements are presented and discussed for hydrophilic silicon dioxide coatings as well as hydrophobic deposits obtained from hexamethyl‐disiloxane. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Plasma Photonic Crystals in Two‐Dimensional Arrays of Microplasmas
Authors: Sakai O. , Sakaguchi T. , Tachibana K. 
Published: February 2007

AbstractTwo‐dimensional arrays of microplasmas form “plasma photonic crystals”, which have new functions that have not been present in bulk plasma. Two features of abnormal electromagnetic wave propagation on the first photonic band above the electron plasma frequency are demonstrated. Near the electron plasma frequency, unidirectional propagation takes place, and divergent propagation occurs near the band gap in the Γ‐X direction. These phenomena are verified in experiments, and the details are confirmed by equi‐frequency contours on a two‐dimensional wavenumber plane. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Erythrocyte morphology automated analysis: Proposal for a new prediction tool of essential hypertension diagnosis
Authors: Teodori Laura , Accorsi Augusto , Uguccioni Francesco , Rocchi Marco B. L. , Baldoni Francesco , Piatti Elena , Albertini Maria Cristina 
Published: February 2007

AbstractBackground:Erythrocyte morphology has already been studied in essential hypertension (EH) and cell membrane alterations have been observed. Relationships among red cell rheological, biochemical, and morphological properties still appear complex and are not clearly understood.Methods:Erythrocyte morphology study was carried out by using the novel automated method we have recently developed. The morphometric parameters derived from optical microscope images were elaborated with image processing software (NIH Scion Image) to construct an application for the principal component analysis (PCA) to achieve a reliable and objective statistical method that would discriminate among erythrocyte morphologies of the considered groups. Three groups of subjects were studied: healthy (n= 30), healthy with familial EH (n= 25), and EH suffering subjects (n= 26).Results:Our results show that morphological modifications are evident in both erythrocytes from EH and from healthy with familial EH subjects as compared to the controls. PCA showed remarkable morphological alterations in EH patients. In fact, the PCA explains for the 86.271% of the total variance that can be considered an excellent result.Conclusions:The results suggest that the use of this automated easy and inexpensive method for the detection of cell shape abnormalities is of high value in the early EH prediction. © 2007 Clinical Cytometry Society
Increased proliferation of CD8+ T cells in SAP‐deficient mice is associated with impaired activation‐induced cell death
Authors: Chen Gang , Tai Albert K. , Lin Miao , Chang Francesca , Terhorst Cox , Huber Brigitte T. 
Published: February 2007

AbstractDefective signaling lymphocyte activation molecule (SLAM)‐associated protein (SAP) is responsible for the human X‐linked lymphoproliferative syndrome. Defects in T helper 2, natural killer, natural killer T and B cells have been demonstrated in SAP‐deficient humans and mice, and increased proliferation of CD8+ T cells has been observed. In the current study, we investigated the properties of CD8+ T cell proliferation and activation‐induced cell death (AICD), using OT‐I T cell receptor (TCR)‐transgenic mice on either wild‐type (WT) or SAP–/– background. Interestingly, we found that ovalbumin peptide‐activated SAP–/– CD8+ T cells have lower AICD compared to their WT counterparts. Furthermore, the induction of p73, a key mediator of TCR‐induced apoptosis through the mitochondrial apoptotic pathway, was significantly reduced at both the mRNA and protein levels in the activated mutant cells. Meanwhile, a reduced level of activated caspase 9 was observed in the mutant cells. We conclude that reduced AICD in activated SAP–/– CD8+ T cells is associated with impaired p73 induction, indicating that the initiation of the mitochondrial apoptotic pathway might be impaired. Our data demonstrate an intrinsic defect in SAP–/– CD8+ T cells and shed light on the increased responsiveness of CD8+ T cells in SAP–/– mice.
Interferon‐regulatory‐factor 1 controls Toll‐like receptor 9‐mediated IFN‐β production in myeloid dendritic cells
Authors: Schmitz Frank , Heit Antje , Guggemoos Simone , Krug Anne , Mages Jörg , Schiemann Matthias , Adler Heiko , Drexler Ingo , Haas Tobias , Lang Roland , Wagner Hermann 
Published: February 2007

AbstractActivation of interferon regulatory factor (IRF)‐3 and/or IRF‐7 drives the expression of antiviral genes and the production of α/β IFN, a hallmark of antiviral responses triggered by Toll‐like receptors (TLR). Here we describe a novel antiviral signaling pathway operating in myeloid (m) dendritic cells (DC) and macrophages that does not require IRF‐3 and/or IRF‐7 but is driven by IRF‐1. IRF‐1 together with myeloid differentiation factor 88 (MyD88) or IL‐1 receptor‐associated kinase (IRAK)‐1 triggered IFN‐β promoter activation. IRF‐1 physically interacted with MyD88 and activation of mDC via TLR‐9 induced IRF‐1‐dependent IFN‐β production paralleled by rapid transcriptional activation of IFN‐stimulated genes. The NF‐κB‐dependent production of pro‐inflammatory cytokines, however, was not influenced by IRF‐1. TLR‐9 signaling through this pathway conferred cellular antiviral resistance while IRF‐1‐deficient mice displayed enhanced susceptibility to viral infection. These results demonstrate that TLR‐9 activation of mDC and macrophages contributes to antiviral immunity via IRF‐1.See accompanying commentary: http://dx.doi.org/10.1002/eji.200637009
CD83 is a regulator of murine B cell function in vivo
Authors: Breloer Minka , Kretschmer Birte , Lüthje Katja , Ehrlich Svenja , Ritter Uwe , Bickert Thomas , Steeg Christiane , Fillatreau Simon , Hoehlig Kai , Lampropoulou Vassiliki , Fleischer Bernhard 
Published: February 2007

AbstractThe transmembrane glycoprotein CD83 has been described as a specific maturation marker for dendritic cells and several lines of evidence suggest that CD83 regulates thymic T cell maturation as well as peripheral T cell activation. Here we show for the first time that CD83 is involved also in the regulation of B cell function. CD83 is up‐regulated on activated B cells in vivo, specifically in the draining lymph nodes of Leishmania major‐infected mice. The ubiquitous transgenic (Tg) expression of CD83 interferes with Leishmania‐specific T cell‐dependent and with T cell‐independent antibody production. This defect is restricted to the B cell population since the antigen‐specific T cell response of CD83Tg mice to L. major infection is unchanged. The defective immunoglobulin (Ig) response is due to Tg expression of CD83 on the B cells because wild‐type B cells display normal antigen‐specific responses in CD83Tg hosts and CD83Tg B cells do not respond to immunization in a mixed wild‐type/CD83Tg bone marrow chimera. Finally, the treatment of non‐Tg C57BL/6 mice with anti‐CD83 mAb induces a dramatic increase in the antigen‐specific IgG response to immunization, thus demonstrating a regulatory role for naturally induced CD83 on wild‐type B cells.
TLR pathways and IFN‐regulatory factors: To each its own
Authors: Colonna Marco 
Published: February 2007

AbstractTLR trigger the induction of type I IFN (IFN‐alpha/beta), providing a crucial mechanism of anti‐viral defense. Until recently, TLR were thought to induce type I IFN responses by activating two transcription factors which belong to the IFN‐regulatory factor (IRF) family, IRF‐3 and IRF‐7. TLR‐3 and TLR‐4 induce IFN‐beta by activating IRF‐3; TLR‐9 induces IFN‐alpha and IFN‐beta through IRF‐7, at least when engaged by type A CpG oligonucleotides (CpG‐A) in plasmacytoid DC (pDC). In this issue of the European Journal of Immunology, it is demonstrated that TLR‐9 induces IFN‐beta when engaged by type B CpG oligonucleotides (CpG‐B) in myeloid DC and macrophages. Remarkably, this response is independent of IRF‐3/7 and, in fact, requires another IRF family member, IRF‐1. IRF‐1 is recruited by TLR‐9 through the adaptor MyD88. Deficiency of the TLR‐9→IRF‐1→IFN‐beta pathway results in impaired anti‐viral responses not only in vitro but also in vivo. These results demonstrate that TLR induce IFN‐alpha or IFN‐beta responses by activating distinct IRF, depending on the TLR ligand and the cell type. These distinct TLR‐IRF pathways may allow the immune system to tailor its responses to viral pathogens.See accompanying article http://dx.doi.org/10.1002/eji.200636767
Mechanistic Studies on the Activation of NO by Iron and Cobalt Complexes
Authors: Franke Alicja , Roncaroli Federico , van Eldik Rudi 
Published: February 2007

AbstractIn this review, the reactions of nitric oxide with selected Fe and Co complexes of biological and environmental importance are reviewed. Fundamental chemical kinetics and mechanisms of reactions that lead to the formation and decay of nitrosyl complexes are illustrated and discussed on the basis of studies on FeIIchelates, FeII/IIIpentacyano complexes, FeIIIporphyrins, cytochrome P450 and model complexes, CoII/IIIporphyrins and vitamin B12. Throughout the review, the focus is on mechanistic details of the binding of NO to and the release of NO from metal complexes and on the nature of the stable metal–NO complexes produced in solution. As will be seen for most of the presented reactions, the interaction of NO with the metal complex involves activation of the small NO molecule so that charge transfer occurs as a result of the formation of the metal–NO bond.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Effect of Voltage on the Topography of Alkanethiol and Poly(amidoamine) Dendrimer Layers with Immobilized Glucose Oxidase. An Atomic Force Microscopy Study
Authors: Polohová Vladimíra , Šnejdárková Maja , Podskočová Jarmila , Svobodová Lenka , Chorvát Dušan , Hianik Tibor 
Published: February 2007

AbstractWe applied atomic force microscopy (AFM) to study the surface topography of the supported thin films of various composition: hexadecanethiol (HDT), poly(amidoamine) dendrimers (PAMAM) of first generation (G1), mixture of HDT+G1, glucose oxidase (GOX) and HDT+G1+GOX layers. The AFM image of dendrimers in air revealed dome‐shaped, randomly distributed aggregates of the size from 100 to 200 nm. GOX adsorbed on the gold support also formed aggregates of the diameter between 700–900 nm and height up to 36 nm. The AFM images of the HDT+G1+GOX layer in air revealed smooth surfaces with irregular pinholes, although these were corrugated in the buffer. Application of the voltage of +670 mV to the layers during one hour resulted in significant increase of the surface root means square roughness (Rrms). The electrical properties of G1 layers studied by cyclic voltammetry do not differ substantially from bare gold electrode, while HDT+G1 mixed layers revealed intermediate electrical properties between HDT and G1. Immobilization of GOX onto the HDT+G1 resulted further decrease of the layer permeability.
Determination of apo‐Metallothionein Using Adsorptive Transfer Stripping Technique in Connection with Differential Pulse Voltammetry
Authors: Adam Vojtech , Krizkova Sona , Zitka Ondrej , Trnkova Libuse , Petrlova Jitka , Beklova Miroslava , Kizek Rene 
Published: February 2007

AbstractLinks between metallothionein (MT), its structure and many biologically important pathways demonstrate the necessity of taking into account of studying the behavior of MT in different well defined mediums, which could help to model conditions in an organism easily. The main aim of this work was to prepare and determine apoMT by adsorptive transfer stripping technique (AdTS) in connection with differential pulse voltammetry (DPV). Particularly, we investigated the electrochemical behavior of MT measured on the surface of hanging mercury drop electrode in the presence of sodium chloride as supporting electrolyte using AdTS DPV with respect to study the effects of MT signals by different concentrations and pH's of the electrolyte. Then, we aimed at utilizing this technique to observe changes in MT which are dependent on using strong chelating compounds ethylendiamine‐N, N, N′, N′‐tetraacetic acid (EDTA). Thanks to ability of EDTA to bind heavy metals from active center of enzymes and regulation proteins, we were able to prepare apoMT; that means, MT without any metal ion bound in its structure. Detection limit of apoMT at very short time of accumulation (tA=120 s) was 3 nM (20 ng/mL and/or 15 fmol in 5 μL drop; RSD=2–5%) estimated by dilution of the analyzed solution until the signal disappeared. In addition, it was possible to decrease detection limit by extending of time of accumulation of apoMT on the surface of HMDE. We were able to detect 30 pM of apoMT (200 pg/mL and/or 150 amol in 5 μL drop) at tA=500 s.
Guidelines for Improving the Lower Detection Limit of Ion‐Selective Electrodes: A Systematic Approach
Authors: Radu Aleksandar , Peper Shane , Bakker Eric , Diamond Dermot 
Published: February 2007

AbstractZero‐current membrane fluxes are the principal source of bias that has prohibited researchers from obtaining true, thermodynamic selectivity coefficients for membrane‐based ion‐selective electrodes (ISEs). They are also responsible for the mediocre detection limits historically seen with these types of potentiometric sensors. By choosing an experimental protocol that suppresses these fluxes, it becomes possible to obtain unbiased thermodynamic selectivity coefficients that are needed to produce ISEs with greatly improved detection limits. In this work, a Cs+‐selective electrode based on calix[6]arene‐hexaacetic acid hexaethyl ester (Cs I) is used to systematically demonstrate how unbiased selectivity coefficients can be obtained, and how they can be used to optimize inner filling solutions for low detection limit measurements. A comparison of biased selectivity methods (e.g., classical separate solution method (SSM), fixed interference method (FIM), matched potential method (MPM)) with the unbiased modified separate solution method (MSSM) found that selectivity coefficients were underestimated in several cases by more than 4 orders of magnitude (log KCs,Mgpot,MSSM=−8.7; log KCs,Mgpot,SSM=−4.5). The importance of key experimental parameters, including diffusion coefficients and diffusion layer thicknesses in the aqueous and organic phases, on the minimization of ion fluxes and the improvement of lower detection limits is also described. A dramatic reduction of membrane fluxes by the covalent attachment of a Ca2+‐selective ionophore to a methyl methacrylate‐decyl methacrylate (MMA‐DMA) copolymer matrix is also demonstrated. The ionophore‐immobilized ISE exhibited no super‐Nernstian response and yielded a detection limit of 40 ppt (log aCa=−9.0) with an inner filling solution of 1×10−3 M KCl. Finally, a set of guidelines for experimental protocols leading to obtaining unbiased selectivity coefficients and producing ISEs for trace level analyses is given.