Identification of stoichiometric and microstructural parameters of a lithium-ion cell with blend electrode.

The measurement of the active material volume fraction in composite electrodes of lithium-ion battery cells is difficult due to the small (sub-micrometer) and irregular structure and multi-component composition of the electrodes, particularly in the case of blend electrodes. State-of-the-art experimental methods such as focused ion beam/scanning electron microscopy (FIB/SEM) and subsequent image analysis require expensive equipment and significant expertise. We present here a simple method for identifying active material volume fractions in single-material and blend electrodes, based on the comparison of experimental equilibrium cell voltage curve (open-circuit voltage as function of charge throughput) with active material half-cell potential curves (half-cell potential as function of lithium stoichiometry). The method requires only (i) low-current cycling data of full cells, (ii) cell opening for measurement of electrode thickness and active electrode area, and (iii) literature half-cell potentials of the active materials. Mathematical optimization is used to identify volume fractions and lithium stoichiometry ranges in which the active materials are cycled. The method is particularly useful for model parameterization of either physicochemical (e.g., pseudo-two-dimensional) models or equivalent circuit models, as it yields a self-consistent set of stoichiometric and structural parameters. The method is demonstrated using a commercial LCO-NCA/graphite pouch cell with blend cathode, but can also be applied to other blends (e.g., graphite-silicon anode).

Rate-Dependent Morphology of Li2O2 Growth in Li-O2 Batteries.

Compact solid discharge products enable energy storage devices with high gravimetric and volumetric energy densities, but solid deposits on active surfaces can disturb charge transport and induce mechanical stress. In this Letter, we develop a nanoscale continuum model for the growth of Li2O2 crystals in lithium-oxygen batteries with organic electrolytes, based on a theory of electrochemical nonequilibrium thermodynamics originally applied to Li-ion batteries. As in the case of lithium insertion in phase-separating LiFePO4 nanoparticles, the theory predicts a transition from complex to uniform morphologies of Li2O2 with increasing current. Discrete particle growth at low discharge rates becomes suppressed at high rates, resulting in a film of electronically insulating Li2O2 that limits cell performance. We predict that the transition between these surface growth modes occurs at current densities close to the exchange current density of the cathode reaction, consistent with experimental observations.

Impedance Spectroscopic Investigation of Proton Conductivity in Nafion Using Transient Electrochemical Atomic Force Microscopy (AFM).

Spatially resolved impedance spectroscopy of a Nafion polyelectrolyte membrane is performed employing a conductive and Pt-coated tip of an atomic force microscope as a point-like contact and electrode. The experiment is conducted by perturbing the system by a rectangular voltage step and measuring the incurred current, followed by Fourier transformation and plotting the impedance against the frequency in a conventional Bode diagram. To test the potential and limitations of this novel method, we present a feasibility study using an identical hydrogen atmosphere at a well-defined relative humidity on both sides of the membrane. It is demonstrated that good quality impedance spectra are obtained in a frequency range of 0.2-1,000 Hz. The extracted polarization curves exhibit a maximum current which cannot be explained by typical diffusion effects. Simulation based on equivalent circuits requires a Nernst element for restricted diffusion in the membrane which suggests that this effect is based on the potential dependence of the electrolyte resistance in the high overpotential region.

Electrochemically induced oxygen spillover and diffusion on Pt(111): PEEM imaging and kinetic modelling.

Electrochemically induced oxygen spillover and diffusion in the Pt(O(2))|YSZ system is investigated in a combined experimental and theoretical study. The spreading of spillover oxygen is imaged by photoelectron emission microscopy (PEEM) on dense and epitaxial Pt(111) thin film electrodes prepared by pulsed laser deposition (PLD). Two different models are used to obtain surface diffusion coefficients from the experimental data, (i) an analytical solution of Fick's 2nd law of diffusion, and (ii) a numerical reaction-diffusion model that includes recombinative desorption of O(2) into the gas phase. The resulting diffusion coefficient has an activation energy of 50 kJ mol(-1) and a preexponential factor of 0.129 cm(2) s(-1) with an estimated uncertainty of ±20% for the activation energy and ±50% for the absolute value. The Fickian model slightly overpredicts diffusion coefficients due to the neglect of oxygen desorption. Experimental and theoretical results and limitations are discussed and compared to previous work.

Passive vaccination with a human monoclonal antibody: generation of antibodies and studies for efficacy in Bacillus anthracis infections.

A major difficulty in creating human monoclonal antibodies is the lack of a suitable myeloma cell line to be used for fusion experiments. In order to create fully human monoclonal antibodies for passive immunization, the human mouse heteromyeloma cell line CB-F7 was evaluated. Using this cell line, we generated human monoclonal antibodies against Bacillus anthracis toxin components. Antibodies against protective antigen (PA) and against lethal factor (LF) were obtained using peripheral blood lymphocytes (PBLs) from persons vaccinated with the UK anthrax vaccine. PBL were fused with the cell line CB-F7. We obtained several clones producing PA specific Ig and one clone (hLF1-SAN) producing a monoclonal antibody (hLF1) directed against LF. The LF binding antibody was able to neutralize Anthrax toxin activity in an in vitro neutralization assay, and preliminary in vivo studies in mice also indicated a trend towards protection. We mapped the epitope of the antibody binding to LF by dot blot analysis and ELIFA using 80 synthetic LF peptides of 20 amino acid lengths with an overlapping range of 10 amino acids. Our results suggest the binding of the monoclonal antibody to the peptide regions 121-150 or 451-470 of LF. The Fab-fragment of the antibody hLF1 was cloned in Escherichia coli and could be useful as part of a fully human monoclonal antibody for the treatment of Anthrax infections. In general, our studies show the applicability of the CB-F7 line to create fully human monoclonal antibodies for vaccination.

Model anodes and anode models for understanding the mechanism of hydrogen oxidation in solid oxide fuel cells.

This article presents a literature review and new results on experimental and theoretical investigations of the electrochemistry of solid oxide fuel cell (SOFC) model anodes, focusing on the nickel/yttria-stabilized zirconia (Ni/YSZ) materials system with operation under H(2)/H(2)O atmospheres. Micropatterned model anodes were used for electrochemical characterization under well-defined operating conditions. Structural and chemical integrity was confirmed by ex situ pre-test and post-test microstructural and chemical analysis. Elementary kinetic models of reaction and transport processes were used to assess reaction pathways and rate-determining steps. The comparison of experimental and simulated electrochemical behaviors of pattern anodes shows quantitative agreement over a wide range of operating conditions (p(H(2)) = 8×10(2) - 9×10(4) Pa, p(H(2)O) = 2×10(1) - 6×10(4) Pa, T = 400-800 °C). Previously published experimental data on model anodes show a strong scatter in electrochemical performance. Furthermore, model anodes exhibit a pronounced dynamics on multiple time scales which is not reproduced in state-of-the-art models and which is also not observed in technical cermet anodes. Potential origin of these effects as well as consequences for further steps in model anode and anode model studies are discussed.

Immunostimulatory properties of the bacterial extract OM-89 in vitro and in vivo.

The therapeutic agent OM-89 (Uro-Vaxom) contains lyophilized immunostimulating fractions from 18 Escherichia coil strains. It has been shown to provide protection against recurrent urinary tract infections in humans and against bacterial infections in mice. Here the immunostimulatory properties of OM-89 were investigated by in vitro and in vivo assays. In vitro the activation of murine spleen cells by the AlamarBlue assay was determined. OM-89 was effective in stimulating the metabolism of spleen cells within a concentration range of 0.625-2.5 mg/ml. The activation of murine bone marrow-derived macrophages by OM-89 was shown by the induction of NO production; OM-89 was a most effective stimulant at concentrations around 6 mg/ml. In the human system, the effect of OM-89 was tested in vitro:metabolic activity of peripheral blood lymphocytes (PBL) was stimulated starting at concentrations of approx. 250 microg/ml, and the spontaneous apoptosis of polymorphonuclear neutrophils (PMN) was reduced starting at OM-89 concentrations of approx. 100 microg/ml. Finally, in a mouse model, the in vivo protection of mice against infection with Salmonella typhimurium after the oral administration of OM-89 was tested (100 mg in a volume of 0.5 ml once a day for 10 consecutive days). The extract proved to be effective: 90% of the OM-89-treated animals survived compared to 58% of the untreated control group.

The bacterial extract OM-85 BV protects mice against influenza and Salmonella infection.

The bacterial extract OM-85 BV has been shown to provide protection against recurrent respiratory infections. We here investigated its efficacy against viral and bacterial infections in murine models. We first evaluated the role of OM-85 BV protecting from an A/PR/8/34 (H1N1) influenza virus infection. In a group treated with 1.75 mg/mouse OM-85 BV all animals survived, compared to 70% in the untreated control group and a group treated with a lower dosage. In addition, the appearance of clinical signs was delayed, their intensity was decreased, and they disappeared faster; also a marked increase in the influenza hemagglutination inhibition antibody level was observed. Since bacterial infections often superimpose viral lung infections, we also investigated on the protection of mice from a Salmonella typhimurium infection after the oral administration of OM-85 BV. Here, 100% of the OM-85 BV treated animals survived compared to 58% of the untreated control group. The mechanism of protection was further investigated: OM-85 BV acts, on the one hand, as an immunogen: the repeated administration of OM-85 BV induced a marked increase in serum antibody levels recognizing pathogenic bacterial strains. On the other hand, the extract acts as a stimulator of the nonspecific macrophage, monocyte, dendritic cell, and granulocyte response. Our findings demonstrate the antimicrobial activity of OM-85 BV against infections, as also has been shown in clinical studies.

Immunomodulating effects of OM-89, a bacterial extract from Escherichia coli, in murine and human leukocytes.

OM-89 (Uro-Vaxom) is a bacterial extract prepared from 18 uropathogenic Escherichia coli strains used for the prevention and treatment of recurrent infections of the urinary tract. The immunomodulating effects of the bacterial extract were investigated in a mouse model. After a single oral administration of OM-89, leukocyte activation was demonstrated ex vivo in blood and liver cells using a chemiluminescence assay. An increase of the production of tumor necrosis factor-alpha (TNF-alpha) in supernatants of peritoneal cells was also observed. After repeated oral administration of OM-89, increased serum immunoglobulin G responses against several E. coli strains were found. Also, adjuvant properties of the extract using ovalbumin as an antigen could be demonstrated. In line with these findings in the mouse system, preliminary in vitro data obtained in the human system showed an increase in TNF-alpha and interleukin-6 production after stimulation of monocyte derived dendritic cells with OM-89. The activation of immune cells is likely to be mediated via Toll like receptors (TLRs); thus, the binding of components of the extract to TLR-4 and marginally to TLR-2 could be shown.

Treatment of hepatitis C virus infection with human ezrin peptide one (HEP1) in HIV infected patients.

This report shows the therapeutic benefit of HEP1 (human ezrin peptide 324-337; TEKKRRETVEREKE) monotherapy of hepatitis C virus (HCV) infection in HIV infected patients in two clinical studies. In the Pilot Study I, 16 of 18 patients responded well to the treatment with significant reductions of HCV viral load and a normalization of serum liver enzymes. In 8 of 18 patients, HCV RNA became undetectable, and 3 of 8 interferon/ribavirin treatment failure patients showed undetectable HCV load following HEP1 treatment. In the second study, 8 of 10 patients responded well to the treatment with a pronounced reduction of the HCV viral load and a normalization of serum liver enzymes. Three of 15 patients (20%) showed an undetectable viral load 30 days after the end of a 30-day course of HEP1 treatment. In both studies, all genotypes of HCV were sensitive to HEP1 treatment. Analysis of the combined data from both studies showed the overall efficacy of HEP1 therapy: in 37 HCV+HIV patients, HEP1 therapy gave the following results: 10 of 37 (27%) HCV+HIV patients showed a reduction of viral load between -7 log (-10,000,000x) and -3 log (-1000x); 4 of 37 (11%) a reduction of -3 log (-1000x); 6 of 37 (16%) a reduction of -2 log (-100x); 11 of 37 (30%) a reduction of -1 log (-10x); 6 of 37 (16%) a reduction of less than -1 log (-10x); 0 of 37 (0%) had an increase in viral load, and the average reduction in viral load for all 37 patients was -2 log (-100x). No adverse reactions or side effects were detected and the improving CD4/CD8 ratio showed that the therapy had no negative impact on the immunological status. Thus, oral HEP1 therapy matches the efficacy results for injectable peginterferon/oral ribavirin therapy with the advantages of more rapid action and less side effects. HEP1 therapy should be used in patients where either peginterferon/ribavirin therapy fails or is contraindicated.

Competitive adsorption of NO, NO2, CO2, and H2O on BaO(100): a quantum chemical study.

Density functional theory (DFT) quantum chemical calculations are used to determine adsorption energies and geometries of NO, NO(2), CO(2), and H(2)O on a barium oxide (100) surface. The study includes two adsorption geometries for NO(2). All species form thermodynamically stable adsorbates, and adsorption strength increases in the order NO(2) < H(2)O < NO

A fetal sheep liver extract containing immunostimulatory substances including LPS acts as leukocyte activator in cells of LPS responder and non responder mice.

Purified fractions from a fetal sheep liver extract (FSLE) were investigated, in a murine model, for induction of leukocyte stimulating activities. The fractions FSLE-1 and FSLE-2 induced splenocyte proliferation in vitro in C57Bl/10ScSn (LPS responder) mice comparable to LPS, and in C57Bl/10ScCr (LPS non responder) mice. They also stimulated the release of nitrogen radicals in bone marrow-derived macrophages (BMDM) from several mouse inbred strains including both C57Bl/10ScSn and C57Bl/10ScCr mice. Stimulation of NO production could be blocked by L-NMMA, an inhibitor of iNOS, and enhanced by the simultaneous addition of IFN-gamma. Moreover, stimulation of macrophages by FSLE-1 and FSLE-2 induced a cytostatic effect of the activated macrophages for Abelson 8-1 tumor cells. The stimulatory activity of the purified fractions is partially due to trace amounts of LPS derived from the fetal liver extract which was enriched during purification. Our results may help to explain the beneficial effect of the extract in patients which has been observed clinically.

Quantitative temperature measurements in high-pressure flames with multiline NO-LIF thermometry.

An accurate temperature measurement technique for steady, high-pressure flames is investigated using excitation wavelength-scanned laser-induced fluorescence (LIF) within the nitric oxide (NO) A-X(0, 0) band, and demonstration experiments are performed in premixed methane/air flames at pressures between 1 and 60 bars with a fuel/air ratio of 0.9. Excitation spectra are simulated with a computational spectral simulation program (LIFSim) and fit to the experimental data to extract gas temperature. The LIF scan range was chosen to provide sensitivity over a wide temperature range and to minimize LIF interference from oxygen. The fitting method is robust against elastic scattering and broadband LIF interference from other species, and yields absolute, calibration-free temperature measurements. Because of loss of structure in the excitation spectra at high pressures, background signal intensities were determined using a NO addition method that simultaneously yields nascent NO concentrations in the postflame gases. In addition, fluorescence emission spectra were also analyzed to quantify the contribution of background signal and to investigate interference in the detection band-width. The NO-LIF temperatures are in good agreement with intrusive single-color pyrometry. The proposed thermometry method could provide a useful tool for studing high-pressure flame chemistry as well as provide a standard to evaluate and validate fast-imaging thermometry techniques for practical diagnostics of high-pressure combustion systems.

Triacyl-lipopentapeptide adjuvants: TLR2-dependent activation of macrophages and modulation of receptor-mediated cell activation by altering acyl-moieties.

Synthetic lipopeptides derived from bacterial lipoprotein are efficient immunoadjuvants. In vitro they activate antigen presenting cells (APCs) to induce the translocation of nuclear factor kappa B (NF-kappaB) and the activation of further transcription factors. This results in the expression of genes encoding cytokines such as IL-1, IL-6, TNF-alpha and in the release of reactive oxygen/nitrogen intermediates. The molecular structure of microbial products determines TLR specificity and thus their activatory potential and immunoadjuvanticity. In the present study, we investigated the lipopeptide-induced activation of leukocytes at different cellular levels by applying derivatives of a synthetic lipopentapeptide-fatty acid library. Our results show that TLR2 plays a key role for the activation of bone marrow-derived macrophages (BMDMs) by lipopentapeptide derivatives and that the fatty acid composition of the lipopeptides determines their activation potential and TLR specificity.

Strategies for laser-induced fluorescence detection of nitric oxide in high-pressure flames. III. Comparison of A-X excitation schemes.

Laser-induced fluorescence (LIF) has proven a reliable technique for nitric oxide (NO) diagnostics in practical combustion systems. However, a wide variety of different excitation and detection strategies are proposed in the literature without giving clear guidelines of which strategies to use for a particular diagnostic situation. We give a brief review of the high-pressure NO LIF diagnostics literature and compare strategies for exciting selected transitions in the A-X(0, 0), (0, 1), and (0, 2) bands using a different detection bandpass. The strategies are compared in terms of NO LIF signal strength, attenuation of laser and signal light in the hot combustion gases, signal selectivity against LIF interference from O2 and CO2, and temperature and pressure sensitivity of the LIF signal. The discussion is based on spectroscopic measurements in laminar premixed methane-air flames at pressures between 1 and 60 bars and on NO and O2 LIF spectral simulations.

Lipopeptide adjuvants in combination treatment.

Synthetic lipopeptides derived from the N-terminus of bacterial lipoprotein constitute potent immunoadjuvants for parenteral and mucosal immunization. When combined with tetanus toxoid (TT) or gliadin as antigens, the lipopeptide N-palmitoyl-S-[2,3-bis(palmitoyloxy)-(2RS)-propyl]-(R)-cysteinyl-seryl-(lysyl)(3)-lysine (P(3)CSK(4)) markedly enhanced the specific antibody levels. Lipopeptides also act as macrophage/monocyte activators: P(3)CSK(4) induced nitric oxide release from bone marrow-derived macrophages (BMDM) of LPS responder and nonresponder mice. The antitumoral effect of the lipopeptide was demonstrated by a strong cytostatic activity of the lipopeptide-treated macrophages against the murine B-cell lymphoma cell line Abelson 8-1. The chemically well-defined lipopeptides can be synthesized with high purity and reproducibility and constitute ideal agents to be combined with antigens/vaccines or antitumor treatment.

Strategies for laser-induced fluorescence detection of nitric oxide in high-pressure flames. II. A-X(0,1) excitation.

A-X(0,1) excitation is a promising new approach for NO laser-induced fluorescence (LIF) diagnostics at elevated pressures and temperatures. We present what to our knowledge are the first detailed spectroscopic investigations within this excitation band using wavelength-resolved LIF measurements in premixed methane/air flames at pressures between 1 and 60 bar and a range of fuel/air ratios. Interference from O2 LIF is a significant problem in lean flames for NO LIF measurements, and pressure broadening and quenching lead to increased interference with increased pressure. Three different excitation schemes are identified that maximize NO/O2 LIF signal ratios, thereby minimizing the O2 interference. The NO LIF signal strength, interference by hot molecular oxygen, and temperature dependence of the three schemes are investigated.

Laser-induced incandescence for soot diagnostics at high pressures.

The influence of pressure on laser-induced incandescence (LII) is investigated systematically in premixed, laminar sooting ethylene/air flames at 1-15 bar with wavelength-, laser fluence-, and time-resolved detection. In the investigated pressure range the LII signal decay rate is proportional to pressure. This observation is consistent with the prediction of heat-transfer models in the free-molecular regime. Pressure does not systematically affect the relationship between LII signal and laser fluence. With appropriate detection timing the pressure influence on LII signal's proportionality to soot volume faction obtained by extinction measurements is only minor compared with the variation observed in different flames at fixed pressures. The implications for particle sizing and soot volume fraction measurements using LII techniques at elevated pressures are discussed.

Strategies for laser-induced fluorescence detection of nitric oxide in high-pressure flames. I. A-X(0,0) excitation.

Three different high-pressure flame measurement strategies for NO laser-induced fluorescence (LIF) with A-X(0,0) excitation have been studied previously with computational simulations and experiments in flames up to 15 bars. Interference from O2 LIF is a significant problem in lean flames for NO LIF measurements, and pressure broadening and quenching lead to increased interference with increased pressure. We investigate the NO LIF signal strength, interference by hot molecular oxygen, and temperature dependence of the three previous schemes and for two newly chosen excitation schemes with wavelength-resolved LIF measurements in premixed methane and air flames at pressures between 1 and 60 bars and a range of fuel/air ratios. In slightly lean flames with an equivalence ratio of 0.83 at 60 bars, the contribution of O2 LIF to the NO LIF signal varies between 8% and 29% for the previous schemes. The O2 interference is best suppressed with excitation at 226.03 nm.

Modulation of the Th1/Th2 bias by lipopeptide and saponin adjuvants in orally immunized mice.

We compared the adjuvanticity of the synthetic lipopeptide P3CSK4 of bacterial origin and the plant-derived adjuvant saponin using the wheat storage protein gliadin as antigen. Gluten sensitive BALB/c mice were orally immunized with gliadin in a mixture with either lipopeptide or saponin. The gliadin-specific serum IgG response was markedly enhanced by the saponin adjuvant. The lipopeptide adjuvant enhanced the IgG2a response, but reduced IgG1 production. In contrast, the saponin adjuvant enhanced both IgG2a and IgG1, and the sera showed elevated specific IgE concentrations. Enhanced specific IgA levels were detected in sera and in faeces especially after immunizations with gliadin in combination with P3CSK4 Enhanced specific IgG and IgA levels could also be detected in supernatants of cell cultures prepared from mesenteric lymph nodes and Peyer's patches of immunized mice. Our data suggest that both adjuvants enhance the mucosal as well as the systemic immune response; P3CSK4 predominantly elicits the activation of the Th1 subset, whereas saponin activates both the Th1 and Th2 subser. Our findings are of importance for the improvement of mucosal immunizations, and might be a tool for the immunotheraphy of food allergies.