Short Pulse Period Research Articles

Turning up the heat: Effects of temperature on agonistic acoustic communication in the two-spotted goby (Pomatoschistus flavescens)

Acoustic communication is linked to fitness traits in many animals, but under the current scenario of global warming, sound signals can be affected by rising temperatures, particularly in ectothermic organisms such as fishes. This study examines the effect of water temperature in acoustic communication in the two-spotted goby, Pomatoschistus flavescens. To address this, we looked at the effect of different temperatures on the acoustic features of drums produced by males during territorial defence and related it with their auditory sensitivity. We also analysed the differences in acoustic features between male agonistic drums and previously reported male courtship sounds, to better understand how acoustic communication may be affected by different temperature conditions. We recorded two-spotted goby males during territorial intrusions for 10 min at 16 °C, 19 °C, and 21 °C in the laboratory. We found that agonistic drums were shorter, had fewer pulses and shorter pulse periods at higher temperature, in contrast with the peak frequency that remained unaffected. Male agonistic and mating drums (recorded in a previous study) at 16 °C only differed in pulse period, which was higher in mating drums. Hearing thresholds obtained with Auditory Evoked Potentials at 16 °C, revealed higher sensitivity below 400 Hz, matching the main energy of agonistic and mating sounds. Our findings suggest that increasing temperature could potentially affect acoustic communication in this species by reducing the duration of agonistic drums, which might hinder effective communication. Nevertheless, the impact may not be significant as there was a good match between the best hearing sensitivity and the peak frequency range of their calls, which was not influenced by temperature. As fish and other organisms are increasingly threatened by multiple anthropogenic stressors, including warming, future research should address how changes in water temperature impact acoustic communication within a more realistic multi-stressor scenario.

Bioacoustics supports genus identification in piranhasa).

In different teleost species, sound production can utilize specific coding schemes to avoid confusion between species during communication. Piranhas are vocal Neotropical fishes, and both Pygocentrus and Serrasalmus produce similar pulsed sounds using the same sound-producing mechanism. In this study, we analysed the sounds of three Pygocentrus and nine Serrasalmus species to determine whether sounds can be used to discriminate piranha species at both the species and genus levels. Our analysis of temporal and frequency data supports the idea that the sounds of Serrasalmus and Pygocentrus species are species specific, and that different acoustic features can be used to differentiate taxa at the genus level. Specifically, the sounds of Serrasalmus species are shorter, louder, and have a shorter pulse period (as determined after correction for standard length). This suggests that sounds can be used to support taxonomy at the genus level as well as the species level.

Pattern transition and regulation in a subthalamopallidal network under electromagnetic effect

Although the significant roles of magnetic induction and electromagnetic radiation in the neural system have been widely studied, their influence on Parkinson’s disease (PD) has yet to be well explored. By virtue of the magnetic flux variable, this paper studies the transition of firing patterns induced by magnetic induction and the regulation effect of external magnetic radiation on the firing activities of the subthalamopallidal network in basal ganglia. We find: (i) The network reproduces five typical waveforms corresponding to the severity of symptoms: weak cluster, episodic, continuous cluster, episodic, and continuous wave. (ii) Magnetic induction is a double-edged sword for the treatment of PD. Although the increase of magnetic coefficient may lead the physiological firing activity to transfer to pathological firing activity, it also can regulate the pathological intensity firing activity with excessive β-band power transferring to the physiological firing pattern with weak β-band power. (iii) External magnetic radiation could inhibit continuous tremulous firing and β-band power of subthalamic nucleus (STN), which means the severity of symptoms weakened. Especially, the bi-parameter plane of the regulation region shows that a short pulse period of magnetic radiation and a medium level of pulse percentage can well regulate pathological oscillation. This work helps to understand the firing activity of the subthalamopallidal network under electromagnetic effect. It may also provide insights into the mechanisms behind the electromagnetic therapy of PD-related firing activity.

Effect of Molten Pool Spatial Arrangement on Texture Evolution in Pulsed Laser Additive Manufacturing of Inconel 718.

The epitaxial growth of dendrites, which often results in a strong texture, is the most common phenomenon during the laser additive manufacturing process. In this study, the epitaxial growth of dendrites and texture evolution in three directions were studied by changing the z-increment, pulse period, and track offset, respectively. The influence of the molten pool interface on the growth and competition of dendrites is analyzed. Both green grains (<110> // BD) with rotated cube texture in the molten pool overlapping zones and red grains (<100> // BD) with fiber texture in the molten pool center zones coexist for different z-increment samples, forming the typical sandwich texture feature. In a short pulse period, the dendrites can grow directly epitaxially and form the strong fiber texture due to gentle interface and short distance. With the decrease of the track offset, the molten pool morphology changes from flat to narrow and deep. When θ is close to 90°, dendrites grow along the secondary dendrite arms at the overlapping zone, forming V-shape grains. This work also provides a promising method for texture customization for laser additive manufacturing.

Vocalization behavior differs across reproductive stages in cultured large yellow croaker Larimichthys crocea (Perciformes: Sciaenidae)

The large yellow croaker (Larimichthys crocea) is among the most important commercial aquaculture fish species in China. Although croakers are known to produce sounds, especially during the spawning season, the relationship between vocal behavior and spawning activity in this species remains largely unknown. In this study, sound production of cultured sexually mature L. crocea was monitored before and during the spawning periods. We estimated the spawning time of L. crocea by examining the embryonic development of fertilized eggs, and divided reproductive stages into four periods (T1-T4) based on the timing of hormonal treatment and spawning of L. crocea. A total of 1340 calls from four periods were analyzed to investigate the relationship between the call characteristics and the different spawning periods. The results demonstrated that L. crocea produced low-frequency pulsed sounds, and sound features differed significantly across reproductive stages in all four periods. During the spawning periods (T3 and T4), longer sounds were produced, with a higher number of pulses per call, a shorter pulse period, and a higher peak frequency than those produced before the spawning periods (T1 and T2). ‘Chorus’ calling was closely related to spawning activity. During the ‘chorus’ periods, the sound pressure level of soundscape in the tank increased by ~30 dB compared to prior no ‘chorus’ periods. Therefore, L. crocea vocalizations can be used as important indicators to determine spawning states and spawning time. We demonstrate that passive acoustic monitoring of L. crocea can provide information about the species spawning time, which will aid in improving both aquaculture management and discovery and protection of spawning habitats of wild L. crocea populations.

Electrochemical machining of microgrooves on flexible metallic foil using a tungsten arrayed microtool

Electrochemical machining (ECM) is a promising method to generate microgrooves in difficult-to-cut materials. This paper utilizes a tungsten arrayed microtool to fabricate microgrooves on a flexible metallic foil via ECM. A pulsed current was employed for refreshing the electrolyte, and a mathematical model was built to explore which factors affect the inter-electrode side and bottom gaps. It implies that several factors such as the pulse-related parameters, microtool size and feed rate, indeed, influence the microgroove dimensions and profiles. Experiments indicated that as the pulse duty cycle and pulse period increased, the effective machining time for the microgrooves was prolonged, thereby increasing both the width and depth of microgroove. Thus, a pulsed current with a small pulse duty cycle and a short pulse period was useful for improving the machining quality of the microgrooves. Moreover, the microgroove dimensions were inversely proportional to the spindle speed due to the higher feed rate. However, the trends of change in the width and depth of the microgrooves were similar as the spindle speed increased, which led to a slight change in the localized etching ratio. For a thicker arrayed microtool, the effective machining time increased, the electrolyte flow path was longer, and the flow field at the machining gap became worse, thereby deteriorating the dimensional consistency and profiles of the microgrooves. Accordingly, the machining quality of microgrooves for a tool electrode thickness of 0.50 mm were considerably better than for a thickness of 1.00 mm.

The Effect of Strong Column-Weak Beam Ratio on the Collapse Behaviour of Reinforced Concrete Moment Frames Subjected to Near-Field Earthquakes

ABSTRACT Buildings are found to be more vulnerable in near-fault regions such that they should be designed with higher strength. In this study, the importance of pulse period and peak ground velocity on the efficiency of the strong column-weak beam ratio (SCWBR) is evaluated through incremental nonlinear dynamic analysis. This work involved two aspects: improving the collapse capacity of structures and mitigation of column damage. Three 4, 8, and 12 story moment frames with varying SCWBR (from 1.2 to 3.0) are subjected to two sets of 44 far-fault and 91 near-fault ground motions. Plastic rotation of elements is utilized as a damage measure for beams and columns. The results demonstrate that idealization of collapse mechanism and early yielding of base columns are controlling factors for the 4 and 12 story buildings, respectively, in particular under long-pulse periods. Moreover, the 8 story (mid-rise) building obtains the highest improvement in the collapse capacity (up to 90%) by the increase of the SCWBR. The most dispersion in the efficiency of the SCWBR among short and large pulse period is observed for the 12 story (high-rise) building. It is also observed that the height-wise distribution of the SCWBR is significantly affected by variation in the pulse period and building height

An in vitro assessment of atrial fibrillation flow types on cardiogenic emboli trajectory paths.

Atrial fibrillation is the most significant contributor to thrombus formation within the heart and is responsible for 45% of all cardio embolic strokes, which account for approximately 15% of acute ischemic strokes cases worldwide. Atrial fibrillation can result in a reduction of normal cardiac output and cycle length of up to 30% and 40%, respectively. A total of 240 embolus analogues were released into a thin-walled, patient-specific aortic arch under normal (60 embolus analogues) and varying atrial fibrillation (180 embolus analogues) pulsatile flow conditions. Under healthy flow conditions (n = 60), the embolus analogues tended to follow the flow rate split through each outlet vessel. There was an increase in clot trajectories along the common carotid arteries under atrial fibrillation flow conditions. A shorter pulse period (0.3 s) displayed the highest percentage of clots travelling to the brain (24%), with a greater percentage of clots travelling through the left common carotid artery (17%). This study provides an experimental insight into the effect varying cardiac output and cycle length can have on the trajectory of a cardiac source blood clots travelling to the cerebral vasculature and possibly causing a stroke.

Effect of the high frequency components of near-fault ground motions on the response of linear and nonlinear SDOF systems: A moving average filtering approach

In this study, the effect of the high frequency components of near fault ground motions (NFGM) with forward rupture directivity effect (FRDE) on the seismic response of elastic and inelastic SDOF regular (non-isolated) and seismic isolated structures is studied. For this purpose, Moving Average filtering method is used to remove the high frequency content of the NFGM at various filtering levels. The key motive for this effort is to evaluate the appropriateness of representing the NFGMs by decomposed signals or mathematical pulse waveforms. Then, elastic and inelastic SDOF structures with various properties are subjected to the original and filtered NFGM and the responses are compared via elastic and inelastic response spectra. In addition, the efficiency of several pulse models in simulating the actual effect of NFGM on the seismic response of elastic and inelastic SDOF structures is investigated. The analyses results revealed that the high frequency content of NFGM has a significant effect on short period elastic structures and inelastic structures with high yield strength subjected to NFGM with short pulse periods. Furthermore, it is found that popular pulse models available in the literature failed to simulate the effect of the actual NFGM on the response of elastic and inelastic structures.

An effective lateral earthquake-resisting system for long-span cable-stayed bridges against near-fault earthquakes

This paper presents a new lateral isolation system consisting of elastoplastic cables and a parallel fluid viscous damper (FVD) for long-span cable-stayed bridges against near-fault earthquakes. A new anchor design is proposed to prevent premature failure at anchor locations, and an experimental test was conducted to validate the force–displacement relationship of the elastoplastic cable. With the new anchor design, the tested cable showed stable plastic behaviour, and the total deformation capacity was increased by at least 3.3 times the maximum elastic deformation capacity. Based on the Yongning Yellow River Bridge model, a numerical analysis was conducted to investigate the isolation mechanism of the new lateral earthquake-resisting system (ERS). Compared with a hypothetical system with ideal elastic cables and an identical parallel FVD, the new system led to similar girder–tower displacements and base bending moments, and evidently smaller forces at the girder–tower connections and girder acceleration responses, indicating better isolation effects gained with the introduction of elastoplastic cables, which provide significant instant energy dissipation against the pulse action. Furthermore, synthetic near-fault ground motions were generated, and comprehensive parameter analyses were carried out to investigate the isolation effectiveness of the new lateral ERS against near-fault ground motions with various pulse properties. The results show that the girder–tower displacement of the laterally isolated cable-stayed bridge was dominated by the mode with predominant lateral girder vibration and the tower responses by the mode with predominant lateral tower vibration. Near-fault ground motions with short pulse periods tend to induce significant internal forces on the tower columns, whereas near-fault ground motions with long pulse periods result in large displacement demands on the ERS. Moreover, an evident correlation between the dynamic characteristics of structures and the pulse period of near-fault ground motions is illustrated.

Removal of dichloroacetic acid from aqueous solution using non-thermal plasma generated by dielectric barrier discharge and nano-pulse corona discharge

In the present work, the efficiencies of non-thermal plasma (NTP) for the removal of dichloroacetic acid (DCA) generated by two different techniques were calculated. The techniques were dielectric barrier discharge (DBD) in a planar falling film reactor and nano-pulse corona discharge (PCD) in a longitudinal horizontal reactor design. The experiments were carried out under various gas atmospheres in the gas-liquid interface. The comparison was performed based on the energy yield (G50) and degree of mineralization measured by total organic carbon (TOC) removal. The experimental results have shown that the degradation and mineralization efficiencies are affected by the input power and the nature of gas. The results show that the decomposition of DCA under argon and helium atmospheres is the most effective method. However, in the presence of sulfobetaine surfactant in the solution a significant reduction in the degradation efficiency was observed due to the scavenging of the reactive radicals generated over the liquid solution and preventing the oxidation of pollutants in the bulk solution. With respect to the energy yield, the nano-pulse corona discharge is more efficient than DBD plasma. Formation of H2O2 under argon atmosphere and ozone generation under (Ar:O2) atmosphere in DBD reactor were investigated and discussed. In the PCD reactor the production of these species is negligible, due to the short plasma pulse period in the nanosecond-scale which decomposing the generated H2O2 and O3, that ultimately lead to enhancing the efficiency in the PCD.

The buzz segment of Savannah sparrow song is a population marker

Different components of learned birdsongs change at different rates across generations, and the rate of change may correspond to the information carried by each component. To characterize the role of the buzz segment of Savannah sparrow songs, we examined recordings from southeastern Canada and the northeastern US and fully characterized buzz segments in songs recorded from two populations: one on Kent Island, NB, Canada and another in Williamstown, MA, USA. Buzzes varied geographically: Kent Island buzzes had higher mean frequencies and shorter pulse periods than Williamstown buzzes and the differences between the two populations persisted over time. Population-specific buzz characteristics also appeared to be resistant to change. Variants appeared on Kent Island in the late 1980s and were learned by some younger birds; however, these buzz variants disappeared by 2011. We conducted a playback experiment and found that males from both populations had longer responses to local buzzes. Therefore, buzz structure varies geographically; population characteristics of the buzz persist through time despite the introduction of variant forms; and territorial males discriminate between buzzes from different populations. The learned buzz segment of the song may thus serve as a population marker for Savannah sparrows.

The correlation between nano-hardness and elasticity and fullerene-like clusters in hydrogenated amorphous carbon films

Fullerene-like hydrogenated carbon films have outstanding mechanical and frictional properties, but their structures have never enjoyed elaboration. In this study, we investigate the relation between nano-hardness and elasticity and fullerene-like clusters by changing energy supply form (direct current and pulse) and H2 concentration in the feedstock. It is found that the films have a network of H-rich amorphous carbon and H-poor or -deficient fullerene-like carbon, and the network change can affect hardness and elastic recovery. This is due to the energy minimization process of the film growing system in a very short pulse period at low temperature.

Determining Kinetic Barriers to Alkaline Hydrogen Oxidation and Evolution Via Oxide Supports

It has long been recognized that the reaction rates of the hydrogen oxidation and hydrogen evolution reactions (HOR and HER) are slower in basic than acidic electrolytes, even though the surface intermediate of adsorbed hydrogen is independent of solution pH. Understanding the root of this observation is critical to designing catalysts for a multitude of electrochemical reactions with relevance to energy conversion and storage. In this work, we undertake a fundamental investigation relating interfacial water structure to the reaction barrier for hydrogen underpotential adsorption and to the HER/HOR kinetics. The pH-dependence of HOR/HER kinetics has been attributed to a variety of reasons. The research groups of Gasteiger and Yan have both suggested that in base, hydroxide ions stabilize the Pt-H bond for stronger binding and slower catalysis1,2. Central to this hypothesis is an experimentally measured shift with pH in the peak potential for hydrogen underpotential deposition on the (100) and (110) steps on the Pt surface. Although it is unclear why pH would stabilize adsorbed hydrogen, stronger binding would push platinum further to the right of the volcano peak and decrease the overall activity. Markovic et al proposed instead that in base, the water recombination/dissociation step of HOR/HER requires specific adsorption of hydroxide ions and therefore optimal binding to two adsorbates3. One observation that has been less discussed than either hydrogen or hydroxide adsorption is the effect of pH not only on the apparent hydrogen adsorption energy, but the kinetic barrier to adsorption. Koper et al attributed this observation to a pH-dependent water orientation at the surface, and hypothesized that “H-down” in acid vs “H-up” in base resulted in slower transfer of hydrogen to and from the surface4. The same pH-dependence of water orientation was recently supported computationally by Rossmeisl's group5. In this work, we examine specifically the hypothesis that water orientation governs the rate of hydrogen adsorption and thus the overall HER/HOR kinetics. The native oxide formed on chromium metal is known from colloidal literature to have a potential of zero charge (Epzc) of 1.22V vs. RHE6. We hypothesize that if water orientation truly governs the alkaline HOR/HER rate, the negative oxide surface charge on chromium oxide will induce an H-down water orientation adjacent to platinum nanoparticles supported on the surface. This will result in faster hydrogen adsorption kinetics and thus, higher activity for alkaline HOR/HER than extended platinum surfaces. To test this hypothesis, platinum nanoparticles were synthesized via pulsed electrodeposition on chromium oxide. The nanoparticle loading was controlled by the duration of deposition pulse, with longer times corresponding to higher coverage as well as larger particles. The hydrogen adsorption kinetics were measured by cyclic voltammetry in the hydrogen underpotential deposition region. Varying the sweep rate results in greater peak separation that can be used to extract rate constants for the adsorption reaction via traditional electroanalysis7. A typical voltammogram of Pt/CrOx in 0.1M KOH is shown in Fig. 1a. As the scan rate increases, kinetic barriers cause greater peak separation (dEp) for hydrogen adsorption on the 100 and 110 facets of platinum. For lower loadings with shorter pulse periods, both smaller currents and smaller peak separations are observed due to the lower Pt surface area. The effects of surface area can be accounted for by normalizing current to Pt surface area as measured by Hupd coulometry. The resulting surface-adsorption Tafel plot is shown in Fig 1b. The peak potential separation dEp is much greater for the larger nanoparticles with higher loading. This difference suggests that smaller particles have qualitatively more rapid adsorption kinetics due to the advantageous water orientation induced by negatively charged CrOx. The results of this study contribute to resolving a long-standing paradox in electrocatalysis and surface science by highlighting the importance of kinetic barriers, as well as adsorption energies, and suggest the ability to modulate alkaline hydrogen activity through metal-support interactions. Future work will discuss the relation of hydrogen underpotential deposition kinetics to HER/HOR activity and the effects of different oxide supports. (1) Durst et al. Energy Environ. Sci. 2014, 2255. (2) Sheng et al. Nat. Commun. 2015, 5848. (3) Strmcnik et al, Nat. Chem. 2013, 1. (4) Van Der Niet et al. Catal. Today 2013, 105. (5) Rossmeis et al. Phys. Chem. Chem. Phys. 2013, 10321. (6) McCafferty, E. Electrochim. Acta 2010, 1630. (7) Angerstein-Kozlowska et al. J. Electroanal. Chem. Interfacial Electrochem. 1979, 1. Figure 1

Influence of Pulse Period and Duty Ratio on Electrochemical Micro Machining (EMM) Characteristics

Electrochemical Micro Machining (EMM) appears to be promising as a future micro machining technique since in many areas of applications; it offers several advantages including electronic, biomedical and MEMS/NEMS applications. Electrochemical Machining (ECM) can be effectively used in the micron range by maintaining very smaller inter electrode gap with proper controlling of predominant micromachining parameters during machining. Present paper will highlight the influence of various EMM process parameters i.e. machining voltage, electrolyte concentration, pulse period and duty cycle ratio on machining performance criteria e.g. material removal rate and machining accuracy to meet the micro machining requirements. Some of the experiments had been carried out on copper to investigate the most effective zone, which gives high machining accuracy with appreciable amount of material removal rate and optimum machining speed. From the experimental results, it has been observed that the introduction of short pulse period improves EMM performance characteristics. Attempt has also been made to study and compare the surface condition of the machined micro holes through SEM micrographs. From the analysis of test results and SEM micrographs it can be observed that optimum value of machining voltage is about 3V, pulse period is about 200 μsec, duty cycle ratio is about 20% and electrolyte concentration is about 20 g/l which will produce accurate micro holes with highest possible amount of material removal.

Sexual dimorphism of sonic apparatus and extreme intersexual variation of sounds in Ophidion rochei (Ophidiidae): first evidence of a tight relationship between morphology and sound characteristics in Ophidiidae

BackgroundMany Ophidiidae are active in dark environments and display complex sonic apparatus morphologies. However, sound recordings are scarce and little is known about acoustic communication in this family. This paper focuses on Ophidion rochei which is known to display an important sexual dimorphism in swimbladder and anterior skeleton. The aims of this study were to compare the sound producing morphology, and the resulting sounds in juveniles, females and males of O. rochei.ResultsMales, females, and juveniles possessed different morphotypes. Females and juveniles contrasted with males because they possessed dramatic differences in morphology of their sonic muscles, swimbladder, supraoccipital crest, and first vertebrae and associated ribs. Further, they lacked the ‘rocker bone’ typically found in males. Sounds from each morphotype were highly divergent. Males generally produced non harmonic, multiple-pulsed sounds that lasted for several seconds (3.5 ± 1.3 s) with a pulse period of ca. 100 ms. Juvenile and female sounds were recorded for the first time in ophidiids. Female sounds were harmonic, had shorter pulse period (±3.7 ms), and never exceeded a few dozen milliseconds (18 ± 11 ms). Moreover, unlike male sounds, female sounds did not have alternating long and short pulse periods. Juvenile sounds were weaker but appear to be similar to female sounds.ConclusionsAlthough it is not possible to distinguish externally male from female in O. rochei, they show a sonic apparatus and sounds that are dramatically different. This difference is likely due to their nocturnal habits that may have favored the evolution of internal secondary sexual characters that help to distinguish males from females and that could facilitate mate choice by females. Moreover, the comparison of different morphotypes in this study shows that these morphological differences result from a peramorphosis that takes place during the development of the gonads.

Fundamental aspects and applications of electrodeposited nanostructured metals

A rational understanding of what occurs during electrocrystallization, defined at a nanolevel, is developed to control electrodeposition processes. The electrokinetic behavior of the elements in solutions and the electrodeposits structure resulting from the electron exchange reaction at the cathodic surface are taken into consideration and compared. Transient electrokinetic parameters are measured with the secondary current pulse (SCP) technique, where a square galvanostatic pulse of a few ms duration is superimposed on the cathode while electrodeposition is running. Two parameters are obtained, the transient Tafel slope and the adsorption pseudo-capacitance; whilst a third parameter, the diffusive time constant, must be introduced if the overvoltage does not arrive to a steady state during the short pulse period. These parameters are related to the growth of different structures and permit a good control of the process. Control of the growth with nanodefinition is key to the development of innovative processes to keep pace with more and more demanding applications and environmental challenges. Examples are given to stress the relevance of the theoretical framework and to show possible implications for electrodeposition technology and its applications.

Hothersall Memorial Award Lecture 2009: Nano-electrodeposition for hard magnetic layers

Electrocrystallisation must be carefully controlled in order to define a magnetic deposit at a nanolevel. A rational approach to the electrodeposition processes in order to control them is presented, taking into consideration and comparing the electrokinetic behaviour of the elements and the electrodeposit structure, resulting from the electron exchange reaction at the cathodic surface. Transient electrokinetic parameters were obtained with the secondary current pulse technique, where a square galvanostatic pulse of a few microseconds' duration is overimposed on the cathode while electrodeposition is running. Two parameters are measured – the transient Tafel slope and the adsorption pseudocapacitance; while a third parameter, the diffusive time constant, must be introduced if the overvoltage does not arrive at a steady state during the short pulse period. These parameters are related to the growth of different structures; this is important for most deposition processes, in particular for nano-electrodeposition of magnetic layers. Two processes for depositing hard magnetic layers are examined: cellular electrodeposition of Co giving hard layers with high magnetic moment, and electrodeposition of CoPt alloys, with high coercivity even at a relatively high thickness. The interactions between Co and Pt during the deposition process and in the deposited layer are underlined.

Abstract P111: Applying the Principles of Functional Stimulation to Electrical CPR

Background: We have previously reported on a specialized electrical stimulus that produces coronary and carotid blood flow during VF. The values selected for the Current (C), Pulse Width (PW), Pulse Period (PP), Train Width (TW) and Train Rate (TR) are critical to obtaining effective blood flow. An initial experiment in which these parameters were systematically studied in order to identify the optimal parameters has been previously reported. In this study we utilized some of the principles established in the field of NeuroMuscular Electrical Stimulation (NMES) of the extremities to further optimize ECPR. A primary principle of interest is that the force produced is proportional to charge delivered (Coulombs or amp-seconds.) Consequently, higher C, longer PW, shorter PP and longer TW would be predicted to produce greater force. Hypothsis: We hypothesized that for ECPR as in NMES that: CPP over time would be proportional to the total charge delivered per constriction. Methods: We applied 118 episodes of ECPR in 7 porcine subjects as previously described. VF was electrically induced and untreated for 10 seconds. ECPR was then applied for 60 seconds or until CPP dropped below 15 mm Hg. The specific ECPR intervention applied was determined according to a factorial design of experiment in which two levels each of C, PW, PP and TW were evaluated. The CPP was recorded at 10-second intervals during ECPR until it was terminated. Results: PP and PW showed significant differences in their ability to maintain CPP &gt; 15 mm Hg (T15) for prolonged periods of time (PP=25 ms: 49±15 s to T15 vs PP=50 ms: 41±17 s to T15, p=0.004) (PW=0.2 ms: 42±17 s to T15 vs PW=0.8 ms: 48±16 s to T15, p=0.05). Regression analysis further showed that an increase in PW and a decrease in PP worked independently and without interaction to increase T15 for CPP. These two parameters relate directly to total charge delivered with the result that, for each additional unit of total charge delivered, there was an almost 8 times increase in the T15 time period (coefficient = 7.7, 95% CI=(6.5,8.9)) Conclusions: The increases in charge provided by longer PP and shorter PW produced significantly longer time of CPP &gt; 15 mm Hg within the limits of this test. Further study is required in order to further extend the duration of action ECPR.

Pulse plating of Ni–W alloys from model electrolytes

Pulse plating of nickel–tungsten alloys has been studied from two citrate ammonia based model electrolytes containing either an excess of nickel or an excess of tungsten. The alloy composition and current efficiency were determined for pulse periods ranging from 1 ms to 50 s at a constant duty cycle of 0˙4. Deposits were analysed by X-ray fluorescence and by gravimetry. In the nickel rich electrolyte the rate of co-deposition of tungsten was found to be controlled by mass transport as previously observed with Ni–Mo alloys. In the tungsten rich electrolyte the tungsten concentration in the deposited alloys was the highest at short pulse periods. This suggests that the deposition rate of tungsten was affected by the rate of transport of nickel which is the highest at short times. As the pulse on time exceeded the transition time for nickel the current efficiency for alloy deposition dropped owing to hydrogen formation.