Effects of inflammatory cytokines on the release and cleavage of the endothelial cell-derived ultralarge von Willebrand factor multimers under flow

ADAMTS13 cleaves ultralarge and hyperreactive von Willebrand factor (ULVWF) freshly released from activated endothelial cells to smaller and less active forms. This process may be affected by the amount of ULVWF released and the processing capacity of ADAMTS13, contributing to the development of thrombotic diseases. We examined the effects of inflammatory cytokines on the release and cleavage of ULVWF to evaluate potential links between inflammation and thrombosis. Human umbilical vein endothelial cells were treated with interleukin 6 (IL-6), IL-8, or tumor necrosis factor alpha (TNF-alpha), and the formation of platelet-decorated ULVWF strings was quantitated. IL-8 and TNF-alpha significantly stimulated the release of ULVWF in a dose-dependent manner. IL-6 induced ULVWF release only when it was in complex with the soluble IL-6 receptor. IL-6, but not IL-8 nor TNF-alpha, inhibited the cleavage of ULVWF strings by ADAMTS13 under flowing, but not static, conditions. These results suggest that inflammatory cytokines may stimulate the ULVWF release (IL-8 and TNF-alpha) and inhibit the ULVWF cleavage (IL-6), resulting in the accumulation of hyperreactive ULVWF in plasma and on the surface of endothelial cells to induce platelet aggregation and adhesion on the vascular endothelium. The findings describe a potential linkage between inflammation and thrombosis that may be of therapeutic importance.

Determination of the formation constants of ternary complexes of uranyl and carbonate with alkaline earth metals (Mg2+, Ca2+, Sr2+, and Ba2+) using anion exchange method

The formation constants of ternary complexes (MUO2(CO3)3(2-) and M2UO2(CO3)3(0)) of uranyl and carbonate with alkaline earth metals (M2+ denotes Mg2+, Ca2+, Sr2+, and Ba2+) were determined with an anion exchange method by varying the metal concentrations (0.1-5 mmol/L) at pH 8.1 and a constant ionic strength (0.1 mol/L NaNO3) under equilibrium with atmospheric CO2. The results indicate that the complexes of MUO2(CO3)3(2-) and M2UO2(CO3)3 are simultaneously formed for Ca2+ and Ba2+, while Mg2+ and Sr2+ form only the MUO2(CO3)3(2-) complex under our experimental conditions. The cumulative stability constants for the MUO2(CO3)3(2-) complex obtained at / = 0 are as follows: logbeta113 = 26.11 +/- 0.04, 27.18 +/- 0.06, 26.86 +/- 0.04, and 26.68 +/- 0.04 for Mg2+, Ca2+, Sr2+, and Ba2+, respectively. For M2UO2(CO3)3(0), the value of logbeta213 at / = 0 was measured to be 30.70 +/- 0.05 and 29.75 +/- 0.07 for Ca2+ and Ba2+, respectively. Based on the formation constants obtained in this study, speciation calculations indicate that at low Ca2+ concentration (e.g., <2.2 mmol/L), CaUO2(CO3)3(2-) is more important than Ca2UO2(CO3)3 and that the Ca2UO2(CO3)3 distribution increased with increasing Ca2+ concentration. Uranium sorption onto anion-exchange resins is inhibited by the formation of the neutral Ca2UO2(CO3)3(0) species.

Self-Assembled Silica-Carbonate Structures and Detection of Ancient Microfossils

We have synthesized inorganic micron-sized filaments, whose microstucture consists of silica-coated nanometer-sized carbonate crystals, arranged with strong orientational order. They exhibit noncrystallographic, curved, helical morphologies, reminiscent of biological forms. The filaments are similar to supposed cyanobacterial microfossils from the Precambrian Warrawoona chert formation in Western Australia, reputed to be the oldest terrestrial microfossils. Simple organic hydrocarbons, whose sources may also be abiotic and indeed inorganic, readily condense onto these filaments and subsequently polymerize under gentle heating to yield kerogenous products. Our results demonstrate that abiotic and morphologically complex microstructures that are identical to currently accepted biogenic materials can be synthesized inorganically.

Highly reversible open framework nanoscale electrodes for divalent ion batteries

The reversible insertion of monovalent ions such as lithium into electrode materials has enabled the development of rechargeable batteries with high energy density. Reversible insertion of divalent ions such as magnesium would allow the creation of new battery chemistries that are potentially safer and cheaper than lithium-based batteries. Here we report that nanomaterials in the Prussian Blue family of open framework materials, such as nickel hexacyanoferrate, allow for the reversible insertion of aqueous alkaline earth divalent ions, including Mg(2+), Ca(2+), Sr(2+), and Ba(2+). We show unprecedented long cycle life and high rate performance for divalent ion insertion. Our results represent a step forward and pave the way for future development in divalent batteries.

Effect of substrate mechanics on chondrocyte adhesion to modified alginate surfaces

This study characterized the attachment of chondrocytes to RGD-functionalized alginate by examining the effect of substrate stiffness on cell attachment and morphology. Bovine chondrocytes were added to wells coated with 2% alginate or RGD-alginate. The alginate was crosslinked with divalent cations ranging from 1.25 to 62.5 mmol/g alginate. Attachment to RGD-alginate was 10-20 times higher than attachment to unmodified alginate and was significantly inhibited by antibodies to integrin subunits alpha3l and beta1, cytochalasin-D, and soluble RGD peptide. The equilibrium level and rate of attachment increased with crosslink density and substrate stiffness. Substrate stiffness also regulated chondrocyte morphology, which changed from a rounded shape with nebulous actin on weaker substrates to a predominantly flat morphology with actin stress fibers on stiffer substrates. The dependence of attachment on integrins and substrate stiffness suggests that chondrocyte integrins may play a role in sensing the mechanical properties of the matrices to which they are attached.

Enhanced aggregation of alginate-coated iron oxide (hematite) nanoparticles in the presence of calcium, strontium, and barium cations

Early-stage aggregation kinetics studies of alginate-coated hematite nanoparticles in solutions containing alkaline-earth metal cations revealed enhanced aggregation rates in the presence of Ca2+, Sr2+, and Ba2+, but not with Mg2+. Transmission electron microscopy (TEM) imaging of the aggregates provided evidence that alginate gel formation was essential for enhanced aggregation to occur. Dynamic light scattering (DLS) aggregation results clearly indicated that a much lower concentration of Ba2+ compared to Ca2+ and Sr2+ was required to achieve a similar degree of enhanced aggregation in each system. To elucidate the relationship between the alginate's affinities for divalent cations and the enhanced aggregation of the alginate-coated hematite nanoparticles, atomic force microscopy (AFM) was employed to probe the interaction forces between alginate-coated hematite surfaces under the solution chemistries used for the aggregation study. Maximum adhesion forces, maximum pull-off distances, and the work of adhesion were used as indicators to gauge the alginate's affinity for the divalent cations and the resulting attractive interactions between alginate-coated hematite nanoparticles. The results showed that alginate had higher affinity for Ba2+ than either Sr2+ or Ca2+. This same trend was consistent with the cation concentrations required for comparable enhanced aggregation kinetics, suggesting that the rate of alginate gel formation controls the enhanced aggregation kinetics. An aggregation mechanism incorporating the gelation of alginate is proposed to explain the accelerated aggregate growth in the presence of Ca2+, Sr2+, and Ba2+.

Test and calibration processes for microcalorimeters, with special reference to heat conduction instruments used with aqueous systems

Calorimeters are normally calibrated by use of electrical heaters, but the calibration values derived may not always be representative for the chemical or biological process investigated. It is therefore important to have available chemical test processes by which the electrical calibration values can be controlled. In some cases, electrical calibration should be replaced by chemical calibrations. With particular reference to needs in work with thermophile heat conduction microcalorimeters, a number of test and calibration processes are presented. Some calibration problems for various types of reaction vessel are discussed.

Molecular dynamics - potential of mean force calculations as a tool for understanding ion permeation and selectivity in narrow channels

Ion channels catalyze the permeation of charged molecules across cell membranes and are essential for many vital physiological functions, including nerve and muscle activity. To understand better the mechanisms underlying ion conduction and valence selectivity of narrow ion channels, we have employed free energy techniques to calculate the potential of mean force (PMF) for ion movement through the prototypical gramicidin A channel. Employing modern all-atom molecular dynamics (MD) force fields with umbrella sampling methods that incorporate one hundred 1-2 ns trajectories, we find that it is possible to achieve semi-quantitative agreement with experimental binding and conductance measurements. We also examine the sensitivity of the MD-PMF results to the choice of MD force field and compare PMFs for potassium, calcium and chloride ions to explore the basis for the valence selectivity of this narrow and uncharged ion channel. A large central barrier is observed for both anions and divalent ions, consistent with lack of experimental conductance. Neither anion or divalent cation is seen to be stabilized inside the channel relative to the bulk electrolyte and each leads to large disruptions to the protein and membrane structure when held deep inside the channel. Weak binding of calcium ions outside the channel corresponds to a free energy well that is too shallow to demonstrate channel blocking. Our findings emphasize the success of the MD-PMF approach and the sensitivity of ion energetics to the choice of biomolecular force field.

Van't Hoff and calorimetric enthalpies from isothermal titration calorimetry: are there significant discrepancies?

The enthalpy of a reaction is most often determined through one of two means; it can be determined directly using calorimetry or indirectly by measuring the temperature dependence of the equilibrium constant (i.e., the van't Hoff method). Recently, discrepancies have been noted between the enthalpy measured by calorimetry, and the enthalpy determined by the van't Hoff method,. This has been suggested to indicate that the binding reaction is more complex than the simple one-to-one binding model used to describe the data. To better understand possible discrepancies between and, we have undertaken both experimental studies using isothermal titration calorimetry to measure the binding energetics of Ba(2+) binding 18-crown-6 ether and 2'-CMP binding RNase A, along with a simulation of a system involving a molecule in conformational equilibrium coupled with binding. We find that when experimental setup and analysis are correctly performed, no statistically significant discrepancies between and exist even for the linked system.

Detection of alkali metal ions in DNA crystals using state-of-the-art X-ray diffraction experiments

The observation of light metal ions in nucleic acids crystals is generally a fortuitous event. Sodium ions in particular are notoriously difficult to detect because their X-ray scattering contributions are virtually identical to those of water and Na(+.)O distances are only slightly shorter than strong hydrogen bonds between well-ordered water molecules. We demonstrate here that replacement of Na(+) by K(+), Rb(+) or Cs(+) and precise measurements of anomalous differences in intensities provide a particularly sensitive method for detecting alkali metal ion-binding sites in nucleic acid crystals. Not only can alkali metal ions be readily located in such structures, but the presence of Rb(+) or Cs(+) also allows structure determination by the single wavelength anomalous diffraction technique. Besides allowing identification of high occupancy binding sites, the combination of high resolution and anomalous diffraction data established here can also pinpoint binding sites that feature only partial occupancy. Conversely, high resolution of the data alone does not necessarily allow differentiation between water and partially ordered metal ions, as demonstrated with the crystal structure of a DNA duplex determined to a resolution of 0.6 A.

Crystallographic studies of metal ion-DNA interactions: different binding modes of cobalt(II), copper(II) and barium(II) to N7 of guanines in Z-DNA and a drug-DNA complex

Metal ion coordination to nucleic acids is not only required for charge neutralization, it is also essential for the biological function of nucleic acids. The structural impact of different metal ion coordinations of DNA helices is an open question. We carried out X-ray diffraction analyses of the interactions of the two transition metal ions Co(II) and Cu(II) and an alkaline earth metal ion Ba(II), with DNA of different conformations. In crystals, Co(II) ion binds exclusively at the N7 position of guanine bases by direct coordination. The coordination geometry around Co(II) is octahedral, although some sites have an incomplete hydration shell. The averaged Co-N7 bond distance is 2.3 A. The averaged Co-N7-C8 angle is 121 degrees, significantly smaller than the value of 128 degrees if the Co-N7 vector were to bisect the C5-N7-C8 bond angle. Model building of Co(II) binding to guanine N7 in B-DNA indicates that the coordinated waters in the axial positions would have a van der Waals clash with the neighboring base on the 5' side. In contrast, the major groove of A-DNA does not have enough room to accommodate the entire hydration shell. This suggests that Co(II) binding to either B-DNA or A-DNA may induce significant conformational changes. The Z-DNA structure of Cu(II)-soaked CGCGTG crystal revealed that the Cu(II) ion is bis-coordinated to N7 position of G10 and #G12 (# denotes a symmetry-related position) bases with a trigonal bipyramid geometry, suggesting a possible N7-Cu-N7 crosslinking mechanism. A similar bis-coordination to two guanines has also been seen in the interaction of Cu(II) in m5CGUAm5CG Z-DNA crystal and of Ba(II) with two other Z-DNA crystals.

Transcript scanning reveals novel and extensive splice variations in human l-type voltage-gated calcium channel, Cav1.2 alpha1 subunit

The L-type (Cav1.2) voltage-gated calcium channels play critical roles in membrane excitability, gene expression, and muscle contraction. The generation of splice variants by the alternative splicing of the poreforming Cav1.2 alpha1-subunit (alpha(1)1.2) may thereby provide potent means to enrich functional diversity. To date, however, no comprehensive scan of alpha(1)1.2 splice variation has been performed, particularly in the human context. Here we have undertaken such a screen, exploiting recently developed "transcript scanning" methods to probe the human gene. The degree of variation turns out to be surprisingly large; 19 of the 55 exons comprising the human alpha(1)1.2 gene were subjected to alternative splicing. Two of these are previously unrecognized exons and two others were not known to be spliced. Comparisons of fetal and adult heart and brain uncovered a large IVS3-S4 variability resulting from combinatorial utilization of exons 31-33. Electrophysiological characterization of such IVS3-S4 variation revealed unmistakable shifts in the voltage dependence of activation, according to an interesting correlation between increased IVS3-S4 linker length and activation at more depolarized potentials. Steady-state inactivation profiles remained unaltered. This systematic portrait of splice variation furnishes a reference library for comprehending combinatorial arrangements of Cav1.2 splice exons, especially as they impact development, physiology, and disease.

Electrophysiological properties of neonatal mouse cardiac myocytes in primary culture

1. The increasing utility of transgenic mice in molecular studies of the cardiovascular system has motivated us to characterize the ionic currents in neonatal mouse ventricular myocytes. 2. Cell capacitance measurements (30 +/- 1 pF, n = 73) confirmed visual impressions that neonatal mouse ventricular myocytes in primary culture are considerably smaller than freshly isolated adult ventricular myocytes. With the use of electron microscopy, mitochondria and sarcoplasmic reticulum were found in close association with myofibrils, but transverse tubules were not observed. 3. Action potential durations, measured at 50 and 90% repolarization, were 23 +/- 1 and 42 +/- 2 ms respectively (n = 46). Application of 4-aminopyridine (4-AP; 5 mM) prolonged action potential duration at 50% repolarization by 26 +/- 5% (n = 3). The brevity of the action potential is explained by the rapid activation of a transient outward K+ current upon voltage-clamp depolarization to plateau potentials. 4. Potassium currents identified include an inward rectifier, a large 4-AP-sensitive transient outward, a slowly inactivating 4-AP-insensitive outward, a slowly activating delayed rectifier and a small rapidly activating E-4031 (10 microM)-sensitive delayed rectifier K+ current. 5. Sodium currents (-305 +/- 50 pA pF-1, n = 21) were recorded in 40 mM Na+ with Ni2+ (1 mM) to block Ca2+ currents and with K+ replaced by Cs+. The relative insensitivity of the Na+ current to block by tetrodotoxin (IC50 = 2.2 +/- 0.3 microM, n = 4) is distinctive of the cardiac Na+ channel isoform. 6. Nitrendipine-insensitive (10 microM) Ba2+ currents elicited during steps from -90 to -30 mV measured -25 +/- 5 pA pF-1 (n = 7, 30 mM Ba2+). Decay of these currents was complete during 180 ms depolarizations, even with Ba2+ as the charge carrier. These currents were not present when the holding potential was set at -50 mV. These data support the presence of a low threshold, T-type Ca2+ current. 7. The maximal nitrendipine-sensitive L-type Ca2+ current density was -10 +/- 2 pA pF-1 (n = 8) in 2 mM Ca2+ and -38 +/- 5 pA pF-1 (n = 9) in 30 mM Ba2+. Exposure to isoprenaline (1 microM) resulted in an 82% increase (n = 3) in the amplitude of the Ba2+ currents elicited at 0 mV. 8. Neonatal mouse cardiac myocytes in primary culture possess surprisingly large inward currents given the brevity of their action potentials.(ABSTRACT TRUNCATED AT 250 WORDS)

New roles of myosin II during vesicle transport and fusion in chromaffin cells

Modified herpes virus (amplicons) were used to express myosin regulatory light chain (RLC) chimeras with green fluorescent protein (GFP) in cultured bovine chromaffin cells to study myosin II implication in secretion. After infection, RLC-GFP constructs were clearly identified in the cytoplasm and accumulated in the cortical region, forming a complex network that co-localized with cortical F-actin. Cells expressing wild type RLC-GFP maintained normal vesicle mobility, whereas cells expressing an unphosphorylatable form (T18A/S19A RLC-GFP) presented severe restrictions in granule movement as measured by individual tracking in dynamic confocal microscopy studies. Interestingly, the overexpression of this mutant form of RLC also affected the initial secretory burst elicited by either high K(+) or BaCl(2), as well as the secretion induced by fast release of calcium from caged compounds in individual cells. Moreover, T18A/S19A RLC-GFP-infected cells presented slower fusion kinetics of individual granules compared with controls as measured by analysis of amperometric spikes. Taken together, our results demonstrate the implication of myosin II in the transport of vesicles, and, surprisingly, in the final phases of exocytosis involving transitions affecting the activity of docked granules, and therefore uncovering a new role for this cytoskeletal element.

A radiotracer study of the adsorption behavior of aqueous Ba(2+) ions on nanoparticles of zero-valent iron

Recently, iron nanoparticles are increasingly being tested as adsorbents for various types of organic and inorganic pollutants. In this study, nanoparticles of zero-valent iron (NZVI) synthesized under atmospheric conditions were employed for the removal of Ba(2+) ions in a concentration range 10(-3) to 10(-6) M. Throughout the study, (133)Ba was used as a tracer to study the effects of time, concentration, and temperature. The obtained data was analyzed using various kinetic models and adsorption isotherms. Pseudo-second-order kinetics and Dubinin-Radushkevich isotherm model provided the best correlation with the obtained data. Observed thermodynamic parameters showed that the process is exothermic and hence enthalpy-driven.

Quantification of the degradation products of sevoflurane in two CO2 absorbants during low-flow anesthesia in surgical patients

Sevoflurane, a new inhalational anesthetic agent has been shown to produce degradation products upon interaction with CO2 absorbants. Quantification of these sevoflurane degradation products during low-flow or closed circuit anesthesia in patients has not been well evaluated. The production of sevoflurane degradation products was evaluated using a low-flow anesthetic technique in patients receiving sevoflurane anesthesia in excess of 3 h. Sevoflurane anesthesia was administered to 16 patients using a circle absorption system with O2 flow of 500 ml/min and average N2O flow of 273 ml/min. Preoperative and postoperative hepatic and renal function studies were performed. Gas samples were obtained from the inhalation and exhalation limbs of the anesthetic circuit for degradation product analysis and analyzed by gas chromatography/mass spectrometry for four degradation products. The first eight patients received sevoflurane anesthesia using soda lime, and the following eight patients received anesthesia using baralyme as the CO2 absorbant. CO2 absorbant temperatures were measured during anesthesia. Of the degradation products analyzed, only one compound [fluoromethyl-2, 2-difluoro-1-(trifluoromethyl) vinyl ether], designated compound A, was detectable. Concentrations of compound A increased during the first 4 h of anesthesia with soda lime and baralyme and declined between 4 and 5 h when baralyme was used. Mean maximum inhalation concentration of compound A using baralyme was 20.28 +/- 8.6 ppm (mean +/- SEM) compared to 8.16 +/- 2.67 ppm obtained with soda lime, a difference that did not reach statistical significance. A single patient achieved a maximal concentration of 60.78 ppm during low-flow anesthesia with baralyme. Exhalation concentrations of compound A were less than inhalation concentrations, suggesting patient uptake.(ABSTRACT TRUNCATED AT 250 WORDS)

Depth heterogeneity of fully aromatic polyamide active layers in reverse osmosis and nanofiltration membranes

We studied the depth heterogeneity of fully aromatic polyamide (PA) active layers in commercial reverse osmosis (RO) and nanofiltration (NF) membranes by quantifying near-surface (i.e., top 6 nm) and volume-averaged properties of the active layers using X-ray photoelectron spectrometry (XPS) and Rutherford backscattering spectrometry (RBS), respectively. Some membranes (e.g., ESPA3 RO) had active layers that were depth homogeneous with respect to the concentration and pK(a) distribution of carboxylic groups, degree of polymer cross-linking, concentration of barium ion probe that associated with ionized carboxylic groups, and steric effects experienced by barium ion. Other membranes (e.g., NF90 NF) had active layers that were depth heterogeneous with respect to the same properties. Our results therefore support the existence of both depth-homogeneous and depth-heterogeneous active layers. It remains to be assessed whether the depth heterogeneity consists of gradually changing properties throughout the active layer depth or of distinct sublayers with different properties.

Mechanosensitivity of N-type calcium channel currents

Mechanosensitivity in voltage-gated calcium channels could be an asset to calcium signaling in healthy cells or a liability during trauma. Recombinant N-type channels expressed in HEK cells revealed a spectrum of mechano-responses. When hydrostatic pressure inflated cells under whole-cell clamp, capacitance was unchanged, but peak current reversibly increased ~1.5-fold, correlating with inflation, not applied pressure. Additionally, stretch transiently increased the open-state inactivation rate, irreversibly increased the closed-state inactivation rate, and left-shifted inactivation without affecting the activation curve or rate. Irreversible mechano-responses proved to be mechanically accelerated components of run-down; they were not evident in cell-attached recordings where, however, reversible stretch-induced increases in peak current persisted. T-type channels (alpha(1I) subunit only) were mechano-insensitive when expressed alone or when coexpressed with N-type channels (alpha(1B) and two auxiliary subunits) and costimulated with stretch that augmented N-type current. Along with the cell-attached results, this differential effect indicates that N-type mechanosensitivity did not depend on the recording situation. The insensitivity of T-type currents to stretch suggested that N-type mechano-responses might arise from primary/auxiliary subunit interactions. However, in single-channel recordings, N-type currents exhibited reversible stretch-induced increases in NP(o) whether the alpha(1B) subunit was expressed alone or with auxiliary subunits. These findings set the stage for the molecular dissection of calcium current mechanosensitivity.

Diastereo- and enantioselective iridium-catalyzed allylation of cyclic ketone enolates: synergetic effect of ligands and barium enolates

We report asymmetric allylic alkylation of barium enolates of cyclic ketones catalyzed by a metallacyclic iridium complex containing a phosphoramidite ligand derived from (R)-1-(2-naphthyl)ethylamine. The reaction products contain adjacent quaternary and tertiary stereocenters. This process demonstrates that unstabilized cyclic ketone enolates can undergo diastereo- and enantioselective Ir-catalyzed allylic substitution reactions with the proper choice of enolate countercation. The products of these reactions can be conveniently transformed to various useful polycarbocyclic structures.

Three-dimensional Rearrangements within Inositol 1,4,5-Trisphosphate Receptor by Calcium

Allosteric binding of calcium ion (Ca2+) to inositol 1,4,5-trisphosphate (IP3) receptor (IP3R) controls channel gating within IP3R. Here, we present biochemical and electron microscopic evidence of Ca2+-sensitive structural changes in the three-dimensional structure of type 1 IP3R (IP3R1). Low concentrations of Ca2+ and high concentrations of Sr2+ and Ba2+ were shown to be effective for the limited proteolysis of IP3R1, but Mg2+ had no effect on the proteolysis. The electron microscopy and the limited proteolysis consistently demonstrated that the effective concentration of Ca2+ for conformational changes in IP3R1 was <10(-7) m and that the IP3 scarcely affected the conformational states. The structure of IP3R1 without Ca2+, as reconstructed by three-dimensional electron microscopy, had a "mushroom-like" appearance consisting of a large square-shaped head and a small channel domain linked by four thin bridges. The projection image of the "head-to-head" assembly comprising two particles confirmed the mushroom-like side view. The "windmill-like" form of IP3R1 with Ca2+ also contains the four bridges connecting from the IP3-binding domain toward the channel domain. These data suggest that the Ca2+-specific conformational change structurally regulates the IP3-triggered channel opening within IP3R1.

Towards the next generation of solid oxide fuel cells operating below 600 °c with chemically stable proton-conducting electrolytes

The need for reducing the solid oxide fuel cell (SOFC) operating temperature below 600 °C is imposed by cost reduction, which is essential for widespread SOFC use, but might also disclose new applications. To this aim, high-temperature proton-conducting (HTPC) oxides have gained widespread interest as electrolyte materials alternative to oxygen-ion conductors. This Progress Report describes recent developments in electrolyte, anode, and cathode materials for protonic SOFCs, addressing the issue of chemical stability, processability, and good power performance below 600 °C. Different fabrication methods are reported for anode-supported SOFCs, obtained using state-of-the-art, chemically stable proton-conducting electrolyte films. Recent findings show significant improvements in the power density output of cells based on doped barium zirconate electrolytes, pointing out towards the feasibility of the next generation of protonic SOFCs, including a good potential for the development of miniaturized SOFCs as portable power supplies.

Phosphatidic acid domains in membranes: effect of divalent counterions

Phosphatidic acid (PA) is emerging as a key phospholipid in a wide range of biological processes such as signal transduction, secretion, or membrane fusion. In most cases, the biological functionality of PA is associated with the presence of micromolar to millimolar calcium concentrations. It has been argued that PA can create defects in the packing of lipids in membranes due to lateral phase separation by divalent ions, which in turn aggregate proteins with high affinity for PA. In this article, we present a detailed investigation of the properties of PA domains in the presence of divalent ions by a combination of molecular dynamics simulations and theoretical methods. Our results show that PA is extremely effective in binding divalent ions through its oxygen atoms, with a broad distribution of binding constants and exhibiting the phenomenon of charge inversion (a total number of bound counterion charges that exceeds the negative PA charge). We predict that a PA-rich domain undergoes a drastic reorganization when divalent cations reach micromolar concentrations (i.e., typical physiological conditions), as PA lipids become doubly charged by releasing their protons. We also present a detailed investigation of the properties of interfacial water, which determine the binding of proteins or other molecules. We conclude with a discussion of the implications of our results in the context of recent experimental studies in model systems and in real cells.

Ba-Catalyzed Direct Mannich-Type Reactions of a β,γ-Unsaturated Ester Providing β-Methylaza-Morita−Baylis−Hillman-Type Products

Barium-catalyzed direct Mannich-type reactions of a beta,gamma-unsaturated ester are described. The Ba-catalyst not only promoted the Mannich-type reactions, but also isomerized Mannich adducts to afford beta-methyl aza-Morita-Baylis-Hillman-type products in 61-88% yield from various aryl, heteroaryl, and alkyl imines. Preliminary trials on enantioselective variants with a chiral biaryldiol ligand gave products in up to 80% ee.

Electrochemical recognition of cations by bis(pyrrolo)tetrathiafulvalene macrocycles

[structure: see text] Tetrathiafulvalene redox-responsive ligands devoid of cis/trans isomerism containing the electroactive bis(pyrrolo[3,4-d])tetrathiafulvalene moiety and polyether subunits have been synthesized. One ligand exhibits high binding affinities for Pb2+ and Ba2+ cations as shown by independent methods (1H NMR, UV-vis spectroscopy, and cyclic voltammetry). The ability of this receptor to electrochemically recognize Pb2+ and Ba2+ is shown by cyclic voltammetry.