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Lanthanum silicate/germanate apatite materials have attracted significant interest as Solid Oxide Fuel Cell electrolytes due to their high oxide ionic conductivity at lower temperatures (500-800 ⁰C). In these structures, oxide ion conduction is due to interstitial pathways associated with the high oxygen excess within the structures. Therefore, cation doped La8+xA2-x(M6-xBxO4)O2+x/2 (A = Ca, Sr, Ba; M = Si and Ge; B = Mg, Ga, Al, Zn, B) have been reported to increase oxide ion conductivity via the introduction of excess oxide ions.[1-3] Whilst apatite silicate has higher conductivities at lower temperatures due to lower activation energies, apatite germanates can achieve higher oxygen excess and therefore higher conductivities at elevated temperatures. However, in increasing oxygen content there is a change in symmetry from hexagonal to triclinic leading to a subsequent reduction in conductivity.[4] Previous studies have shown the issue may be overcome by the incorporation of Y doping e.g La8Y2GeO6O27 which leads to stabilisation of the higher conducting hexagonal phase.[5] Herein, we demonstrate the successful incorporation of borate into La10-xYxGeO6O27 and show that it also stabilises the higher conducting hexagonal form. We show that B can be doped into both the Ge site and the oxide ion channels. Interestingly, the conductivity of samples with borate in the channels (which would be expected to block channel oxide ion conductivity along the c direction) is still reasonably high, which supports suggestions that there is significant conduction perpendicular to the channels in these apatite germanates. [1] A Orera and P R Slater, Chem. Mater 2010 22 675-690 [2] P M Panchmatia, A Orera, G J Rees, M E Smith, J. V. Hanna, P. R. Slater and M. S. Islam, Angew. Chem. Int. Ed, 2011 50 9328-9333 [3] E Kendrick, M S Islam and P R Slater, J. Mater. Chem 2007 17 3104-3111. [4] M S Chambers, P Chater, I R Evans and J S Evans, Inorg. Chem., 2019 58(21)14853-14862, [5] A Najib, J. E. H. Sansom, J. R. Tolchard, P. R. Slater and M. S. Islam, Dalton Trans., vol. 19, pp. 3106-3109, 2004.

Ion currents through potassium channels are gated. Constriction of the ion conduction pathway at the inner helix bundle, the textbook ‘gate’ of Kir potassium channels, has been shown to be an ineffective permeation control, creating a rift in our understanding of how these channels are gated. Here we present the first evidence that anionic lipids act as interactive response elements sufficient to gate potassium conduction. We demonstrate the limiting barrier to K+ permeation lies within the ion conduction pathway and show that this ‘gate’ is operated by the fatty acyl tails of lipids that infiltrate the conduction pathway via fenestrations in the walls of the pore. Acyl tails occupying a surface groove extending from the cytosolic interface to the conduction pathway provide a potential means of relaying cellular signals, mediated by anionic lipid head groups bound at the canonical lipid binding site, to the internal gate.

The 4TM family of K channels mediate many of the background potassium currents observed in native cells. They are open across the physiological voltage-range and are regulated by a wide array of neurotransmitters and biochemical mediators. The pore-forming α-subunit contains two pore loop (P) domains and two subunits assemble to form one ion conduction pathway lined by four P domains. It is important to note that single channels do not have two pores but that each subunit has two P domains in its primary sequence; hence the name two-pore domain, or K2P channels (and not two-pore channels). Some of the K2P subunits can form heterodimers across subfamilies (e.g. K2P3.1 with K2P9.1). The nomenclature of 4TM K channels in the literature is still a mixture of IUPHAR and common names. The suggested division into subfamilies, described in the More detailed introduction, is based on similarities in both structural and functional properties within subfamilies and this explains the "common abbreviation" nomenclature in the tables below.

The 4TM family of K channels mediate many of the background potassium currents observed in native cells. They are open across the physiological voltage-range and are regulated by a wide array of neurotransmitters and biochemical mediators. The pore-forming α-subunit contains two pore loop (P) domains and two subunits assemble to form one ion conduction pathway lined by four P domains. It is important to note that single channels do not have two pores but that each subunit has two P domains in its primary sequence; hence the name two P domain, or K2P channels (and not two-pore channels). Some of the K2P subunits can form heterodimers across subfamilies (e.g. K2P3.1 with K2P9.1). The nomenclature of 4TM K channels in the literature is still a mixture of IUPHAR and common names. The suggested division into subfamilies, described in the More detailed introduction, is based on similarities in both structural and functional properties within subfamilies and this explains the "common abbreviation" nomenclature in the tables below.

Aim. To present potentials of electrocardiographic (ECG) research method in the diagnosis of paroxysmal tachycardia, as well as in the presence of additional conduction pathways (DPP). To demonstrate potentials of a trivial method for identification of the type of arrhythmia, the mechanism of occurrence, and topics of the additional conduction pathway in Wolf-Parkinson-White syndrome on a clinical example. Conclusion. A widely available routine method of the ECG allows to determine the nature of arrhythmia, to choose the treatment tactics, to assess the prognosis of the disease, prior to performing complex invasive procedures.

Kainate receptors are involved in several neuropathologies, but their gating process remains to be fully understood. Wilding and Huettner identify two residues at the extracellular end of the GluK2 inner helix where cysteine substitution results in direct activation by cadmium., Kainate receptors are ligand-gated ion channels that have two major roles in the central nervous system: they mediate a postsynaptic component of excitatory neurotransmission at some glutamatergic synapses and modulate transmitter release at both excitatory and inhibitory synapses. Accumulating evidence implicates kainate receptors in a variety of neuropathologies, including epilepsy, psychiatric disorders, developmental delay, and cognitive impairment. Here, to gain a deeper understanding of the conformational changes associated with agonist binding and channel opening, we generate a series of Cys substitutions in the GluK2 kainate receptor subunit, focusing on the M3 helices that line the ion pore and form the bundle-crossing gate at the extracellular mouth of the channel. Exposure to 50 µM Cd produces direct activation of homomeric mutant channels bearing Cys substitutions in (A657C), or adjacent to (L659C), the conserved SYTANLAAF motif. Activation by Cd is occluded by modification with 2-aminoethyl MTS (MTSEA), indicating that Cd binds directly and specifically to the substituted cysteines. Cd potency for the A657C mutation (EC50 = 10 µM) suggests that binding involves at least two coordinating residues, whereas weaker Cd potency for L659C (EC50 = 2 mM) implies that activation does not require tight coordination by multiple side chains for this substitution. Experiments with heteromeric and chimeric channels indicate that activation by Cd requires Cys substitution at only two of the four subunits within a tetrameric receptor and that activation is similar for substitution within subunits in either the A/C or B/D conformations. We develop simple kinetic models for the A657C substitution that reproduce several features of Cd activation as well as the low-affinity inhibition observed at higher Cd concentrations (5–20 mM). Together, these results demonstrate rapid and reversible channel activation, independent of agonist site occupancy, upon Cd binding to Cys side chains at two specific locations along the GluK2 inner helix.

Background: Multiple atrial tachycardias (ATs) in one patient usually require more complex ablation procedures. Despite the superior accuracy and understanding of conduction features provided by high-resolution mapping, Multiple ATs are still associated with high recurrence rates, and other mechanisms may play a role. Therefore, we aimed to uncover the substrates maintaining these multiple reentrant circuits and the probable mechanisms for the high occurrence of arrhythmia. Methods: Mapping via the Carto system was carried out in 8 patients with more than two types of reentrant circuits during ablation. Functional conduction block (FCB) regions were marked and further analyzed. Results: Twenty sustained ATs were mapped in the 8 patients. Five of these patients exhibited a potential FCB region that changed between different ATs. The potentials of these regions converted between double potentials (DPs), fractionated potentials (FPs) and normal potential due to the different ATs. The FCB regions were the main obstacles and the center of the reentrant circuit in 8 of 14 ATs, and in the other ATs, these regions played a role in reorganizing the conduction pathway. In the activation mapping, the FCB areas were never the target ablation site. Conclusion: The potential FCB region is common in ATs with more than two types of reentrant circuits, especially in scar-related localized reentry. The convertibility of FCB regions provide one of the critical substrates in maintaining multiple ATs. The changefulness of this substrate may be one of the important causes of the high recurrence of related ATs

Cardiac hydatidosis is an unusual disease and the interventricular septum is infrequently involved. It can cause various complications because of rupture and embolization. Interventricular septal cysts, may in rare conditions, induce symptoms corresponding to compression of the conduction pathway such as atrioventricular block. In this report, we present an uncommon case of cardiac echinococcus located in the basal part of the interventricular septum presenting as complete heart block managed by medical treatment and implantation of a permanent pacemaker.

With the coming of the big data age, the resistive switching memory (RSM) of three-dimensional (3D) high density shows a significant application in information storage and processing due to its simple structure and size-scalable characteristic. However, an electrical initialization process makes the peripheral circuits of 3D integration too complicated to be realized. Here a new forming-free SiCx:H-based device can be obtained by tuning the Si dangling bond conductive channel. It is discovered that the forming-free behavior can be ascribed to the Si dangling bonds in the as-deposited SiCx:H films. By tuning the number of Si dangling bonds, the forming-free SiCx:H RSM exhibits a tunable memory window. The fracture and connection of the Si dangling bond conduction pathway induces the switching from the high-resistance state (HRS) to the low-resistance state (LRS). Our discovery of forming-free SiCx:H resistive switching memory with tunable pathway opens a way to the realization of 3D high-density memory.

Quantitative analysis of complex atrial intramural microstructure is a crucial step towards understanding the mechanism behind atrial fibrillation (AF) maintenance. Siamese network was adopted to extract features from computationally simulated multi-layer fibrosis structure. Through analysis of the features produced by the feature extractor, the difference between Non-sustained and Sustained simulations was comprehended intuitively and electrophysiologically. Complex conduction pathway marked by the feature extractor might be an indicator for AF radio-frequency ablation clinically.

New structural work sheds light on the architecture of otopetrin channels, offering insights into the mechanisms for proton permeation in this family.

Objectives To investigate the usefulness of measuring the electrically evoked auditory brainstem responses (eABRs) to electrical stimulation at the round window niche (RWN) and round window membrane (RWM) and the effect of deafness duration on functions of the auditory pathway to the level of the brainstem. Methods According to the age at cochlear implantation (CI), 99 children with profound sensorineural hearing loss were divided into four groups: ≤12 months (group A), 13–36 months (group B), 37–60 months (group C) and >60 months (group D). The eABRs were evoked by electrical stimulation at RWN and RWM during the operation of CI. Results The higher eABR extraction rate and lower threshold for RWM stimulation was found than those for RWN stimulation. The eⅢ latencies and eⅢ-eⅤ latency intervals for RWM stimulation were similar among four groups. However, children with earlier CI (group A) showed a significantly shorter eⅤ latency than others. Conclusion The eABR evoked by the electrical stimulation at RWM is more stable and sensitive compared with that at RWN for evaluating functions of the auditory conduction pathway. Development in the upper brainstem pathway may be more vulnerable to long-term deafness as revealed by the eⅤ latency.

The 4TM family of K channels mediate many of the background potassium currents observed in native cells. They are open across the physiological voltage-range and are regulated by a wide array of neurotransmitters and biochemical mediators. The pore-forming α-subunit contains two pore loop (P) domains and two subunits assemble to form one ion conduction pathway lined by four P domains. It is important to note that single channels do not have two pores but that each subunit has two P domains in its primary sequence; hence the name two P domain, or K2P channels (and not two-pore channels). Some of the K2P subunits can form heterodimers across subfamilies (e.g. K2P3.1 with K2P9.1). The nomenclature of 4TM K channels in the literature is still a mixture of IUPHAR and common names. The suggested division into subfamilies, described in the More detailed introduction, is based on similarities in both structural and functional properties within subfamilies and this explains the "common abbreviation" nomenclature in the tables below.

Marijuana is the most commonly abused recreational substance. With the increasing legalization of marijuana, its use is expected to rise. Delta-9-tetrahydrocannabinol (THC) is the psychotropic component of marijuana, acting via CB1 and CB2 G-protein coupled cannabinoid receptors. Marijuana has serious cardiovascular effects including tachycardia, orthostatic hypotension, angina and myocardial infarction to name a few. Previous reports by our group and others documented various arrhythmias other than atrioventricular nodal reentrant tachycardia (AVNRT) that are associated with marijuana use. In this report, we present a case of AVNRT associated with marijuana use. Marijuana in high doses stimulates parasympathetic nerves. While parasympathetic stimulation can increase the refractory period of the fast conduction pathway, it has no effect on the slow and retrograde pathways, therefore its use creates an ideal milieu for AVNRT initiation and maintenance. Our case report highlights the importance of including marijuana use in the differential diagnosis, as a possible trigger, for patients presenting with AVNRT that is otherwise unexplainable.

Detection of bound water in a potassium channel by solid-state NMR supports the “direct” knock-on ion permeation mechanism., Ion conduction through potassium channels is a fundamental process of life. On the basis of crystallographic data, it was originally proposed that potassium ions and water molecules are transported through the selectivity filter in an alternating arrangement, suggesting a “water-mediated” knock-on mechanism. Later on, this view was challenged by results from molecular dynamics simulations that revealed a “direct” knock-on mechanism where ions are in direct contact. Using solid-state nuclear magnetic resonance techniques tailored to characterize the interaction between water molecules and the ion channel, we show here that the selectivity filter of a potassium channel is free of water under physiological conditions. Our results are fully consistent with the direct knock-on mechanism of ion conduction but contradict the previously proposed water-mediated knock-on mechanism.

Sound transmission and reception are both vital components to odontocete echolocation and daily life. Here, we combine computed tomography (CT) scanning and finite element modeling to investigate the acoustic propagation of finless porpoise (Neophocaena asiaorientalis sunameri) echolocation pulses. The CT scanning and finite element method wave propagation model results support the well-accepted jaw-hearing pathway hypothesis and suggest an additional alternative auditory pathway composed of structures, mandible (lower jaw) and internal mandibular fat, with different acoustic impedances, which may also conduct sounds to the ear complexes. The internal mandibular fat is attached to the ear complex and encased by the mandibles laterally and anteriorly. The simulations show signals in this pathway initially propagate along the solid mandibles and are transmitted to the acoustically coupled soft tissue of the internal mandibular fat which conducts the stimuli posteriorly as it eventually arrives at ear complexes. While supporting traditional theories, this new bone-tissue conduction pathway might be meaningful to understand the hearing and sound reception processes in a wide variety of odontocetes species.

The performance of GaN-on-Silicon electronic devices is severely degraded by the presence of a parasitic conduction pathway at the nitride-substrate interface which contributes to switching losses and lower breakdown voltages. The physical nature of such a parasitic channel and its properties are however, not well understood. We report on a pronounced thickness dependence of the parasitic channel formation at AlN/Si interfaces due to increased surface acceptor densities at the interface in silicon. The origin of these surface acceptors is analyzed using secondary ion mass spectroscopy measurements and traced to thermal acceptor formation due to Si-O-N complexes. Low-temperature (5K) magneto-resistance (MR) data reveals a transition from positive to negative MR with increasing AlN film thickness indicating the presence of an inversion layer of electrons which also contributes to parasitic channel formation but whose contribution is secondary at room temperatures., Comment: 23 pages, 7 figures

Nowadays the techniques used to fabricate electronic devices have their deposition resolution limited. The production of an ion source that could allow the deposition of copper onto substrates with high-resolution, in order to write those pathways, is extremely important. The main objective of this MSc thesis was to prove that it is possible to emit copper ions from a copper tip that is covered with a copper-based solid electrolyte. This goal encompasses several important and complex tasks like the synthesis of the appropriate electrolyte, the production of sufficiently sharp copper tips, the transfer of the electrolyte onto the copper tip, while preserving its original geometry, performing field ion emission experiments and the detection of deposited copper. The solid electrolyte used in this work was the Rb4Cu16I7Cl13, which has the highest ionic conductivity reported until today. During this work, we tried different options in synthesizing the electrolyte and ended up with an optimized approach to do so. The synthesized materials were characterized by X-ray Photoelectron Spectroscopy, Powder X-ray Diffraction and Electrochemical Impedance Spectroscopy, in order for us to confirm that the materials were in the desired phase. We tried different approaches to deposit the electrolyte onto the tips - the pressing of the powder electrolyte onto the tips, with and without heating, dipping the tips in an acetone suspension made with the electrolyte powder and physical vapour deposition, using an evaporator built for this purpose. None of these methods gave satisfactory results, but we were able to deposit some electrolyte onto the tip using the acetone suspension method. Even though the deposition of the electrolyte onto the tips was not as good as we desired, we still managed to get some ion current from the acetone prepared sample. Although the current was not very stable, Secondary Ion Mass Spectroscopy analysis of the graphite substrate showed that we were able to mostly emit copper ions, with a small contribution of rubidium ions.

The P2X receptor is a trimeric transmembrane protein that acts as an ATP-gated ion channel. Its transmembrane domain (TMD) contains only six helices and three of them, the M2 helices, line the ion conduction pathway. Here, using molecular dynamics simulation, I identify four conformational states of the TMD that are associated with four types of packing between M2 helices. Packing in the extracellular half of the M2 helix produces closed conformations, while packing in the intracellular half produces both open and closed conformations. State transition is observed and supports a mechanism where iris-like twisting of the M2 helices switches the location of helical packing between the extracellular and the intracellular halves of the helices. In addition, this twisting motion alters the position and orientation of residue side-chains relative to the pore and therefore influences the pore geometry and possibly ion permeation. Helical packing, on the other hand, may restrict the twisting motion and generate discrete conformational states. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s10867-018-9493-8) contains supplementary material, which is available to authorized users.

In developed countries cardiac diseases are still the number one cause of death. For this reason, research aims to understand physiological and pathological processes of the heart. Proper functioning of the heart and therefore, the supply of organs with blood is triggered by electrical activity. For each contraction of ventricles an excitation of action potentials through the cardiac cells has preceded. Research to model the excitation of the heart is a relevant topic in order to understand ongoing coherences in the heart and be able to test cardiac devices in vitro. Therefore, in this model we demonstrate a physiological motivated abstracted simulation of the vectorcardiogram (VCG). In this model, we developed the conduction pathway of action potentials in the heart by applying a predefined propagation direction. The segmentation of heart was performed in order to distinguish between the different existing heart tissues. A tree structure was implemented, in-which each node of the tree represents a cardiac cell and each edge of the tree structure the transition between cells. Therefore, the edges of the conduction tree are weighted with the conduction velocity in the considered heart area. Due to the predefined conduction orientation a reduction in complexity can be achieved. The choice of a simple volume conductor facilitates the transfer from the source signals to the chosen observing points on the volume conductor. The simulation of a lead system similar to the Frank lead system shows morphological reasonable results, so that for further investigation the simulation of pathological scenarios is conceivable. Typical characteristics of the VCG like P-Loop, QRS-Loop and the T-Loop are clearly identifiable. The reduction of complexity promises to reach real-time capability using this model for testing in ECG-triggered medical devices [1].

A 74-year-old woman who developed atrial tachycardia following the Cox-Maze IV procedure underwent catheter ablation. The reentrant circuit included the coronary sinus (CS), Marshall bundle (MB), distal MB-left atrial (LA) connection, and anterolateral mitral annulus. The distal MB-LA connection was the last barrier in the conduction pathway between the CS and the left atrium. Keywords: Atrial tachycardia, Catheter ablation, Coronary sinus, Left atrial appendage, Marshall bundle

The current study delineates the effect of Odia and Tamil music on the Autonomic Nervous System (ANS) and cardiac conduction pathway of Odia volunteers. The analysis of the ECG signals using Analysis of Variance (ANOVA) showed that the features obtained from the HRV domain, time-domain and wavelet transform domain were statistically insignificant. But non-linear classifiers like Classification and Regression Tree (CART), Boosted Tree (BT) and Random Forest (RF) indicated the presence of important features. A classification efficiency of more than 85% was achieved when the important features, obtained from the non-linear classifiers, were used. The results suggested that there is an increase in the parasympathetic activity when music is heard in the mother tongue. If a person is made to listen to music in the language with which he is not conversant, an increase in the sympathetic activity is observed. It is also expected that there might be a difference in the cardiac conduction pathway.

Low ionic conductivity is one of the issues for polymer electrolytes to be used in commercial batteries, though they have been viewed as the promising electrolytes in all-solid lithium-ion batteries for several decades. Here, we show an enhanced ionic conductivity in a classic polymer electrolyte by controlling the ionic conductive pathway via a core–shell structure. The enhancement in ionic conductivity is contributed from the formation of a controlled 3D network of the ion conductive amorphous phase. The result suggests that the core–shell structure design can realize the control of the conduction pathway, which is significant for understanding the ionic conductive behaviors as well as for the improvement of the ionic conductivity in polymer electrolytes.

Hydrated cocrystal of gallic acid–isoniazid displays a single crystal-to-single crystal transformation upon dehydration, resulting in a difference of three orders of magnitude in proton conduction. The conduction pathway is shown to follow the Grotthus mechanism, supported by theoretical (DFT) calculations.

Uniaxially-aligned sulfonated polyimide (SPI) nanofibers fabricated by an electrospinning method showed ultra-high proton conductivities above 1 S cm−1 at 30–90 °C and 95% RH. Higher applied voltage between the parallel electrodes during the electrospinning process gave higher proton conductive SPI nanofibers due to the formation of an effective proton conduction pathway by molecular orientation in the nanofibers.

The current study investigates the effect of sound in a horror movie clip on the autonomic nervous system (ANS) and the conduction pathway of the heart. The effect on ANS was explored non-invasively using heart rate variability (HRV) parameters. The results suggested that the physiology of ANS is not significantly affected by the sound stimulus. Electrocardiogram (ECG) signal divulges information about the cardiac electrophysiology. The time-domain and joint time-frequency domain processed ECG signals were classified using artificial neural networks (ANN). The classification results suggested the functional changes in the conduction pathway of the heart.

The current study reports the effect of regular Cannabis sativa (bhang) consumption on the autonomic nervous system (ANS) and the conduction pathway of the heart of the Indian paddy field workers. Twenty-four paddy field workers were selected for the study and electrocardiogram (ECG) signal was recorded. The physiological modulation in the ANS was analyzed in a non-invasive manner using heart rate variability (HRV) parameters. The results suggested a sympathetic dominance in the bhang users. ECG signal divulges information about the cardiac physiology and the conduction pathway of the heart. Time-domain and joint time-frequency domain analyses of ECG signal suggested alterations in the cardiac conduction pathway of bhang users. Artificial neural network based classification using the important predictors as categorical inputs resulted in an efficiency of > 80%.

The current study deals with the heart rate variability (HRV) and wavelet-based ECG signal analysis of smokers and non-smokers. The results of HRV indicated dominance towards the sympathetic nervous system activity in smokers. The heart rate was found to be higher in case of smokers as compared to non-smokers (p 90 % was achieved. The wavelet decomposition of the ECG signal was done using the Daubechies (db 6) wavelet family. No difference was observed between the smokers and non-smokers which apparently suggested that smoking does not affect the conduction pathway of heart.

Pyridinol, a coordinating zwitter-ionic species serves as stoichiometrically loadable and non-leachable proton carrier. The partial replacement of the pyridinol by stronger hydrogen bonding, coordinating guest, ethylene glycol (EG), offers 1000-fold enhancement in conductivity (10−6 to 10−3 Scm−1) with record low activation energy (0.11 eV). Atomic modeling coupled with 13C-SSNMR provides insights into the potential proton conduction pathway functionalized with post-synthetically anchored dynamic proton transporting EG moieties.

In this study, the effect of slow and fast music on the heart rate variability and conduction pathway of the heart was studied. The results indicated an increase in the parasympathetic dominance as the volunteers were made to listen to music. The magnitude of the parasympathetic activity was higher when the volunteers were made to listen to fast music. This indicates that slow and fast music affected the sympatho-vagal balance in different proportions. The analysis of the ECG signal and wavelet transformed ECG signal suggested an alteration in the conduction pathway of the heart.

Christine Cottrell discusses the physiological basis of atrial fibrillation and considers its causes and risk factors Alliance group

INTRODUCTION This study aims to characterize the regional variability in rate-adaptation in the atria. METHODS AND RESULTS Action potential (AP) responses to pulses with uniform as well as pseudo-random non-uniform pacing intervals were recorded from rabbit sino-atrial node, right and left atrial pectinate as well as pulmonary vein antrum tissue preparations using conventional intracellular glass microelectrodes. Steady-state restitution curves were reconstructed for various AP waveform metrics. We observed significant variability between the four regions under basal pacing representing the rabbit resting heart rate as well as regional variability in rate-adaptation to increased pacing frequencies. Right-left atrial restitution differences were further confirmed using the non-uniform pacing protocol, with significant differences in AP amplitude, duration (APD) as well as maximum phase 0 depolarization rate restitution curves in response to an identical sequence of non-uniform pacing intervals. In addition, we report regional differences in alternans of AP waveform metrics, over a wide range of pacing frequencies and not simply prior to 1:1 entrainment being lost. We also observed an increase in APD90 along the conduction pathway from the left atrium to pulmonary vein junction. CONCLUSIONS Our results identified significant regional differences in electrical restitution in the rabbit atria and suggest their dependency on both baseline AP morphology and local intrinsic differences in rate-adaptation. We propose that the atrial heterogeneity in rate-adaptation could contribute to arrhythmogenesis and the greater susceptibility of pulmonary vein myocardial sleeves to ectopic foci and reentrant activity.

The ablation of parahisian accessory pathways is a challenge because of the risk of atrioventricular block. In this observation, we describe the case of an eleven-year-old girl presenting a parahisian accessory pathway treated successfully by cryoablation. It is a pediatric case, in which, the accessory pathway and the nodo-hisian conduction pathway where superposed in anatomic and electrophysiological terms. Cryoablation should be the method of choice of ablation in pediatric patients.

We demonstrate here the synthesis of a hierarchical TiO(2) architecture without any surfactants or templates. Two kinds of structure existed simultaneously, the ordered nanoarrays at bottom provided direct conduction pathway for photo generated electrons, while the upper micro-flowers consisted of nanobelt as building units increased the light harvesting ability as the scattering part. The formation mechanism of the hierarchical architecture has been proposed by studying the morphology evolution processes upon reaction time. The performance of dye-sensitized solar cells based on the obtained hierarchical anatase TiO(2) has been also studied, giving a J(SC) = 12.44 mA cm(-2), V(OC) = 0.64 V, FF = 69.05%, and η = 5.53%, which is superior than commercial TiO(2) (P25). The UV-vis results prove that the obtained morphology is beneficial to light-scattering and thus increases the light harvesting ability. This hierarchical TiO(2) structure offers great potential for the development of high-efficiency DSSCs.

The pore-lining amino acids of ion channel proteins reside on the interface between a polar (the pore) and a nonpolar environment (the rest of the protein). The structural dynamics of this region, which physically controls ionic flow, are essential components of channel gating. Using large-conductance, Ca(2+)-dependent K(+) (BK) channels, we devised a systematic charge-substitution method to probe conformational changes in the pore region during channel gating. We identified a deep-pore residue (314 in hSlo1) as a marker of structural dynamics. We manipulated the charge states of this residue by substituting amino acids with different valence and pKa, and by adjusting intracellular pH. We found that the charged states of the 314 residues stabilized an open state of the BK channel. With models based on known structures of related channels, we postulate a dynamic rearrangement of the deep-pore region during BK channel opening/closing, which involves a change of the degree of pore exposure for 314.

Dr. Arthur M. "Buzz" Brown is the founder and CEO of ChanTest Corporation, an ion channel company specializing in drug discovery and safety services. He is Adjunct Professor of Physiology and Biophysics, School of Medicine, Case Western Reserve University. Dr. Brown has more than 30 years of experience in ion channel structure-function relationships and their associations with human health. He established world-leading ion channel departments at University of Texas Medical Branch, Baylor College of Medicine, and Case Western Reserve University. His lab first applied liquid ion exchanger ion-selective microelectrodes to single cells, introduced the concept of membrane delimited action of G proteins on ion channels, identified the ion channel conduction pathway or pore of voltage-gated channels and inwardly rectifying potassium channels, showed that the human ether-a-go-go-related gene potassium channel was the molecular target for lethal arrhythmias associated with noncardiac drugs, and established that noncardiac drugs could also produce lethal arrhythmias by inhibiting ion channel trafficking. Dr. Brown holds eight patents on ion channel methodology and application of ion channel pharmacology to therapeutics.

Computational model systems are used to explore improving the transmission through a molecular device based on bridged cobalt(II) complexes. The bridging ligands and the organic conjugated molecular ligands are altered to improve the current flow through both an enhanced pi-stacking interaction as well as involving the metal ions directly in the conduction pathway. With terpyridine as the organic ligand, both acetate and NH2- produce conductive devices, while a terpyridine complex bridged by Cl- is not conductive. The addition of a fused ring on either end of the conjugated molecule has a complex effect which is sensitive to the bridged ligand and the particular geometry of the complex.