Dual Chamber Research Articles

An Unusual Cause of AV Dyssynchrony: Dual AV Node Physiology With Retrograde Decremental Conduction

A 71-year-old male with persistent atrial fibrillation and a dual chamber permanent pacemaker presented complaining of dyspnea on exertion, easy fatiguability, and intermittent cough. A 12-lead electrocardiogram revealed ventricular paced complexes, native QRS complexes, and irregular atrial activity. Herein we present an unusual mechanism of atrioventricular dyssynchrony. (Level of Difficulty: Intermediate.)

A new concept for high efficiency and clean diesel combustion by controlling mixture distribution with dual zone combustion chamber

While various measures are being promoted globally toward carbon-neutrality, internal combustion engines are required to achieve a further improvement in thermal efficiency in order to generate less CO2. For diesel engines, premixed charge compression ignition (PCI) combustion has been proposed as a combustion method that can achieve high thermal efficiency and clean emissions simultaneously. However, the application of PCI combustion remains limited to the light load range of certain mass-produced engines as it is difficult to control ignition timing and combustion noise. In this study, we developed a new combustion concept, Distribution Controlled partially Premixed Compression Ignition (DCPCI), which enables partially premixed combustion in medium load ranges by spatially controlling fuel mixture distribution. With this DCPCI combustion, we aim for highly efficient and clean combustion by suppressing the interference between the burned gas produced by the earlier stage injection and the subsequent spray with the use of a dual-zone combustion chamber and multi-stage injection. The effectiveness of the new combustion concept was validated by Computational Fluid Dynamics (CFD) analyses, and the improvement in thermal efficiency was confirmed by engine experiments.

Effects of External Resistance, New Electrode Material, and Catholyte Type on the Energy Generation and Performance of Dual-Chamber Microbial Fuel Cells

In this study, the effects of an external resistance, new electrode material, and non-conventional catholyte on the energy generation and performance of a dual-chamber MFC were evaluated. Ten different resistances (15 Ω–220 kΩ), hydrophilically-treated graphene and graphite electrodes, and a 0.1 M HCl solution as a catholyte were assessed. The results showed that greater energy generation and power density were achieved at an external resistance of 2 kΩ and internal resistance between 2 and 5 kΩ on average; meanwhile, the greatest coulombic efficiency was obtained at the lowest external resistance evaluated (15 Ω). Therefore, it is recommended to operate the MFCs at the external resistance between 2 and 5 kΩ to ensure the maximum power generation of the dual chamber MFCs. Regarding the two electrode materials evaluated as an anode and cathode, hydrophilically-treated graphene was found to be a much better material to enhance the energy production and performance of the MFC system; therefore, its use is suggested in experimental and practical applications. On the other hand, the use of HCl as a catholyte enhanced the performance of MFC (constant and steady potential and greater coulombic efficiency) in most cases.

Electrochemical Deposition (ECD) of ZnO as the Photoanode in Dual‐Chamber Photocatalytic Fuel Cell (PFC) for Methyl Red Degradation

AbstractPhotocatalytic fuel cell (PFC) is known to treat the organic‐based wastewater efficiently. The coating method of zinc(II) oxide (ZnO) as the photocatalyst on the zinc (Zn) plate of photoanode plays important role in maintaining the efficiency and power generation from PFC. In the present study, a new coating method of ZnO on the zinc plate is developed by using electrochemical deposition (ECD) and the removal efficiency as well as power generation are compared with typical ultrasonicate method. A dual‐chamber PFC is constructed with ZnO/Zn photoanode and graphite plate as the cathode to treat methyl red dye synthetic wastewater. The surface morphology of both coating methods of ZnO/Zn photoanode is observed using scanning electron microscope (SEM) before and after the treatments. The dual chamber PFC with ECD coating shows a faster complete degradation rate with higher power generation than ultrasonicate method. Although, both coating methods can reach to 100% degradation efficiency of methyl red dye, the maximum power output for ultrasonicate method is 134.67 mW cm−2 while for ECD is 285.30 mW cm−2 under optimum conditions.

Production of acetone, butanol, and ethanol by electro-fermentation with Clostridium saccharoperbutylacetonicum N1-4

This manuscript describes the effect of altering the extracellular redox potential during the production of acetone, butanol, and ethanol on a dual chamber H-type microbial fuel cell by fermenting glucose with Clostridium saccharoperbutylacetonicum N1-4. Extracellular redox potential modification was achieved by either supplementing the microbial broth with the redox agent NADH or by poising the cathode potential at −600 mV vs. Ag/AgCl. The addition of NADH was found to foment the production of acetone via fermentation of glucose. The addition of 200 mM of NADH to the catholyte rendered the highest production of acetone (2.4 g L-1), thus outperforming the production of acetone by conventional fermentation means (control treatment) by a factor of 2.2. The experimental evidence gathered here, indicates that cathodic electro-fermentation of glucose favors the production of butanol. When poising the cathode potential at −600 mV vs Ag/AgCl (electro-fermentation), the largest production of butanol was achieved (5.8 g L-1), outperforming the control treatment by a factor of 1.5. The production of ABE solvents and the electrochemical measurements demonstrate the electroactive properties of C. saccharoperbutylacetonicum N1-4 and illustrates the usefulness of bio-electrochemical systems to improve conventional fermentative processes.

A drop in heart rate and cardiac output during cardiopulmonary stress testing in a patient with a dual chamber pacemaker.

The authors declare no conflicts of interest. Not applicable. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Improvement of bioenergy generation using innovative application of food waste materials for coating carbon nanotubes-loaded bioanode in 3D-microbial fuel cells

In this study, an innovative use of date seeds and banana peels wastes coupled with multi walled carbon nanotubes (MWCNTs) was applied for the first time for coating the anodic electrodes in 3D-MFCs to improve power generation. Two of identically styled and designed dual chamber 3D-MFCs were set up and operated in a continuous manner for simultaneous treatment of carwash wastewater and energy recovery. Both MFCs were packed with acid activated irregular-shaped graphite granules (ISGG) coated with MWCNTs coupled with date seeds powder in 3D-MFC1 and with banana peels powder in 3D-MFC2. The results revealed that maximum elimination efficiencies of COD, sodium dodecyl sulfate (SDS), as well as oil and grease (O&G) were 99.4%, 99.9% and 98.2%, respectively in the 3D-MFC1 while they were 96.8%, 99.9% and 93.9%, respectively in the 3D-MFC2. Maximum power density of 1072 mW/m3 and 730 mW/m3 were observed in the 3D-MFC1 and 3D-MFC2, respectively.

Novel non-invasive ECG imaging method based on the 12-lead ECG for reconstruction of ventricular activation: A proof-of-concept study.

Current non-invasive electrocardiographic imaging (ECGi) methods are often based on complex body surface potential mapping, limiting the clinical applicability. The aim of this pilot study was to evaluate the ability of a novel non-invasive ECGi method, based on the standard 12-lead ECG, to localize initial site of ventricular activation in right ventricular (RV) paced patients. Validation of the method was performed by comparing the ECGi reconstructed earliest site of activation against the true RV pacing site determined from cardiac computed tomography (CT). This was a retrospective study using data from 34 patients, previously implanted with a dual chamber pacemaker due to advanced atrioventricular block. True RV lead position was determined from analysis of a post-implant cardiac CT scan. The ECGi method was based on an inverse-ECG algorithm applying electrophysiological rules. The algorithm integrated information from an RV paced 12-lead ECG together with a CT-derived patient-specific heart-thorax geometric model to reconstruct a 3D electrical ventricular activation map. The mean geodesic localization error (LE) between the ECGi reconstructed initial site of activation and the RV lead insertion site determined from CT was 13.9 ± 5.6 mm. The mean RV endocardial surface area was 146.0 ± 30.0 cm2 and the mean circular LE area was 7.0 ± 5.2 cm2 resulting in a relative LE of 5.0 ± 4.0%. We demonstrated a novel non-invasive ECGi method, based on the 12-lead ECG, that accurately localized the RV pacing site in relation to the ventricular anatomy.

The XeBRA platform for liquid xenon time projection chamber development

XeBRA is a flexible cryogenic platform designed to perform research and development for liquid xenon detectors searching for rare events. Its extra-large outer cryostat makes it possible to install a wide variety of detector designs. We present the system, including its cryogenic, gas handling, data acquisition and slow control subsystems. Two dual phase time projection chambers with sensitive masses at the 1 kg scale have so far been operated in XeBRA. Using data from these, we determine the field-dependence of the electron drift velocity in liquid xenon. We also measure the relative charge and light yields for 41.5 keV energy deposits from 83mKr with electric drift fields between 50 V/cm and 677 V/cm.

The Australian and New Zealand Cardiac Implantable Electronic Device Survey, Calendar Year 2021: 50-Year Anniversary.

A cardiac implantable electronic device (CIED) survey was undertaken in Australia and New Zealand for calendar year 2021. The survey involved pacemakers (PMs) and implantable cardioverter-defibrillators (ICDs). The survey was conducted on the 50th anniversary of the first survey for both Australia and New Zealand in 1972; that initial survey being conducted by two of the current authors. For 2021, there were 19,410 PMs (17,971 in 2017) sold in Australia for new implants and 2,282 (1,811 in 2017) sold in New Zealand. The number of new PM implants per million population was 755 for Australia (745 in 2017) and 446 for New Zealand (384 in 2017). Unlike previous recent surveys, the percentage of PM replacements compared to total sales in both Australia and New Zealand rose. Pulse generator types implanted were predominantly dual chamber; Australia 77% (73% in 2017) and New Zealand 70% (68% in 2017). There were 1,509 biventricular PMs implanted in Australia (1,247 in 2017) and 172 in New Zealand (118 in 2017). Transvenous pacing leads were >90% active fixation in the atrium and ventricle. There was an increase in ICD usage with Australia 4,519 new implants (4,212 in 2017) and New Zealand 449 (396 in 2017). New ICD implants per million population were 187 for Australia (175 in 2017) and 88 for New Zealand (90 in 2017). For the first time the survey included implantable event monitors with 6,933 being implanted in Australia. However, for proprietary reasons, survey figures for subcutaneous implantable defibrillators, leadless pacemakers and conduction system pacing have not been included. Both Australia and New Zealand have high PM and ICD implant numbers compared to the rest of the Asia Pacific region.

Electrochemical impedance spectroscopy studies of the buffered and non‐buffered microbial fuel cell

AbstractThe positive effect of buffers to maintain a sui pH for microorganism growth and increase the electrolyte conductivity in microbial fuel cells (MFCs) encourages more studies on the development of new buffer solutions. The effect of types of biological buffers such as phosphate, tris, succinate, and maleate on power production in dual chamber MFC inoculated by saccharomyces cerevisiae has been examined. Electrochemical impedance spectroscopy has been used for evaluating the performance of the buffered and non‐buffered MFC systems. Considering the important impact of buffer type on the resistance of ion migration within the electrolyte and electron transport resistance of the cell components, the internal resistance of the MFC with different used buffers has been obtained and compared. According to the obtained results, the tris buffer solution showed a positive influence on the power output with a power density of 25.41% higher than phosphate.

Influence of non-apical permanent pacing on left ventricular systolic impairment

Abstract Funding Acknowledgements Type of funding sources: None. Background Right ventricular apical (RVA) pacing deleterious effects on left ventricular ejection fraction (LVEF) had been demonstrated. Non-apical pacing, such as right ventricular mid-septal (RVMS) and His Bundle pacing, appear as practical alternatives. Our purpose is to evaluate the effect of alternate sites of right ventricular (RV) pacing on left ventricular (LV) function and hemodynamics in patients with bradyarrhythmias. Methods We observed 118 patients (age 58±27 years, 64% men) with AV block III, who underwent permanent dual chamber pacemaker implantation. To 72 patients RV lead has implanted the middle area of RV septum (RVMS) and 46 patients’ RV lead has been implanted traditionally to the right ventricular apex (RVA). Color tissue velocity imaging was performed to analyze time to peak systolic velocity (Ts) in a 12 segment model of the LV for each pacing site. Measurements included standard deviation of time to peak systolic velocity (SD-Ts) for all segments, the maximal difference in Ts between any 2/6 basal (Ts-B), any 2/6 mid segments (Ts-M) and maximal Ts difference between any 2/12 segments (Ts-12). Stroke volume was estimated using Doppler velocity time integral (TVI) in the left ventricular outflow tract (LVOT). QRS width for each site was recorded. Measurements were observed by transthoracic echocardiography and electrocardiography before and 12 months after implantation. Results Ts-12 was significantly higher with RVA - pacing (107 ms, p=0.003) compared to RVMS - pacing (81 ms) sites. SD-Ts were significantly higher with RVA - pacing (38.5 ms, p=0.01) than RVMS - pacing (28.7 ms). QRS duration was the longest for RVA - pacing (157 ms) while significantly shorter RVMS - pacing (115 ms, p<0.001). LVOT VTI was significantly higher for RVMS - pacing than for RVA (p=0.0014) pacing. Conclusions Right ventricular mid-septal pacing may reduce electro-mechanical dyssynchrony compared to RVA pacing and RVMS – pacing to effect better LV function and hemodynamics than RVA pacing in patients with permanent pacemaker implantation.

Numerical study on the hydrodynamic performance of a symmetrical dual-chamber oscillating water column wave energy converter

In this study, a novel floating oscillating water column (OWC) wave energy converter (WEC) with dual chambers is proposed, and its hydrodynamic performance and primary energy conversion characteristics are investigated by numerical calculation. It consists of a floating body and two long vertical pipes opening downward at the bottom, forming dual chambers at the top. These two rectangular pipes are fixed to the front and back ends of the buoyancy tank with the same width, and it can be regarded as an oscillating single floating body as a whole. Under the action of the incident wave, the WEC captures wave power by the heave motion and relative motion of the pipe and the water column in it to form an oscillating water column, outputting pneumatic power. The geometry size of the vertical pipes is optimized by comparing the hydrodynamic performance and capture width ratio (CWR) of the WEC models with several rectangular pipes of different sizes. The calculation results show that increasing the draft, which is positively correlated with the total mass of the WEC model, increases its optimal response period. By comparing the numerical calculation results of the hydrodynamic performance and CWR of the WEC models with three kinds of floater bottom shapes, semi-cylindrical, sharp-bottomed, and flat-bottomed, it is found that the flat-bottomed model has the best capture performance.

Performance of Sediment Microbial Fuel Cells in Generating Electricity using Fish Wastewater and Shrimp Wastewater as a Nutrient and Their Effect on Waste Quality

Sediment Microbial Fuel Cell (MFC) is a technology that can convert chemical energy into electrical energy through the process of nutrient degradation by microbes. Sediment taken from the bottom of shrimp ponds was added as a source of microbes, while fish and shrimp wastewater were used as a source of nutrients for microbes. This study aims to measure the performance of the SMFC system on fish effluent and shrimp effluent to produce bio-electricity while reducing the waste load. The research method was experimental laboratories. The treatment given was the different types of electrodes, namely zinc-copper and aluminum-copper. In addition, 0.2 M KMnO4 electrolyte solution was used. This study consisted of four stages: the manufacture of nutrients from fish and shrimp wastewater, the manufacture of a dual chamber MFC bioreactor, the measurement of electrical values, and the analysis of waste quality. Experiments were carried out for 30 days by measuring electricity every 24 hours. The average value of electricity generated in the nutrients of fish wastewater with Zn/Cu electrodes was 0.705 V and Al/Cu was 0.472 V. Meanwhile, the average value of electricity in shrimp wastewater nutrients with Zn/Cu electrodes was 0.630 V and Al/Cu was 0.625 V. The number of colonies after adding sediment in the shrimp wastewater sample were 8.9 x 106 CFU/mL, the fish wastewater sample was 9.5 x 106 CFU/mL. It indicates the presence of microorganisms that play a role in the SMFC system

New particle formation and growth during summer in an urban environment: a dual chamber study

Abstract. Nucleation and subsequent growth are a major source of new particles in many environments, but the pollutants involved and the details of the corresponding processes are still under debate. While sulfuric acid has a major role in new particle formation under a lot of conditions, the role of ammonia, amines, and organic vapors is less clear. In most continental areas, new particle formation is quite frequent especially on relatively clean, sunny days when there is some sulfur dioxide available. In parts of the Eastern Mediterranean even if all the previous requirements are satisfied, new particle formation events are relatively rare during summertime. In this work, we take advantage of this unexpected low, new particle formation frequency in Greece and use a dual atmospheric simulation chamber system with starting point ambient air in an effort to gain insight about the chemical species that is limiting nucleation in this area. A potential nucleation precursor, ammonia, was added in one of the chambers, while the other one was used as a reference. Three different types of outcomes were observed: new particle formation only in the perturbed chamber, new particle formation in both chambers, and no observed new particle formation. The addition of ammonia assisted in new particle formation in almost 50 % of the experiments conducted. The growth rate of the newly formed particles ranged from 3–11 nm h−1, with particles reaching a diameter of 20–25 nm after a few hours. The nucleation rate was estimated using an aerosol dynamics model and was found to be in the range of 500 to 25 000 particles cm−3 h−1 in the different experiments. These results support the hypothesis that ammonia at levels of several ppb can accelerate or even cause new particle formation, at least in the environment of the Eastern Mediterranean.

Role of electrode and proton exchange membrane configurations on microbial fuel cell performance toward bioelectricity generation integrated wastewater treatment

In the present study, the effects of electrode surface area, proton exchange membrane area, and volume of the anodic chamber were investigated on the performance of five different dual chamber microbial fuel cells (MFC) using synthetic wastewater toward wastewater treatment coupled electricity generation. In the batch mode, the five different MFC's were operated with the anodic chamber volumes of 93–890 mL, 17.33–56.77 cm2 electrode surface area, obtained volumetric power densities of 137.72–58.13 mW/m3, and unit area power densities ranging from 27.04 to 11.94 mW/m2. Fed-batch studies were done with the MFC having 740 mL anodic chamber volume at different wastewater COD concentrations. The power density per unit area increased from 22.93 mW/m2 to 36.25 cm2 when the distance between electrodes was reduced from 10 to 6 cm. A maximum volumetric power density of 135.21 mW/m3 has been attained with a 6 cm electrode distance with the accomplished COD reduction of 93.21%. The presence of biofilm on the anode has been visualized through the SEM images. The higher COD concentration of wastewater and the fed-batch operation resulted in increased power output and wastewater treatment efficiency.

Improving Wave Energy Conversion Performance of a Floating BBDB-OWC System by Using Dual Chambers and a Novel Enhancement Plate

Improving Wave Energy Conversion Performance of a Floating BBDB-OWC System by Using Dual Chambers and a Novel Enhancement Plate

Direct Detection of Dark Matter with DarkSide-20k

DarkSide run since mid 2015 a 50-kg-active-mass dual phase Liquid Argon Time Projection Chamber (TPC), filled with low radioactivity argon from an underground source and produced world class results for both the low mass (< 20 GeV/c2) and high mass ( > 100 GeV/c2) direct detection search for dark matter. The next stage of the DarkSide program will be a new generation experiment involving a global collaboration from all the current Argon based experiments. DarkSide-20k, is designed as a 20-tonne fiducial mass dual phase Liquid Argon TPC with SiPM based cryogenic photosensors, and is expected to be free of any instrumental background for an exposure of >100 tonne year. Like its predecessor, DarkSide-20k will be housed at the INFN Gran Sasso (LNGS) underground laboratory, and it is expected to attain a WIMP-nucleon cross section exclusion sensitivity of 7.4 × 10−48 cm2 for a WIMP mass of 1 TeV/c2 in a 200 t yr run. DarkSide-20k will be installed inside a membrane cryostat containing more than 700 t of liquid Argon and be surrounded by an active neutron veto based on a Gd-loaded acrylic shell. The talk will give the latest updates of the ongoing R&D and prototype tests validating the initial design. A subsequent objective, towards the end of the next decade, will be the construction of the ultimate detector, ARGO, with a 300 t fiducial mass to push the sensitivity to the neutrino floor region for high mass WIMPs.

Radiated Susceptibility Assessment of Interconnected Systems Within Dual Reverberation Chamber

The interconnected systems (ISs) are commonly exposed to electromagnetic environments with different maximum field levels, and the measurement technique on how to perform radiated susceptibility (RS) test is one of the most attractive research topics of the electromagnetic compatibility (EMC) community. In this work, the dual reverberation chamber (DRC) is used to reveal the potential EMC issues of the IS, which also provides a comparison with the RS tests performed in a conventional RC. By using a typical IS on the ship, we highlight the evidence supporting IS to conduct the RS tests in the DRC. Taken together, the results show that the IS will be more sensitive within the DRC and expose more acute EMC problems on one hand; on the other hand, the IS also presents a larger probability of sensitivity.

Clinical Comparison of Cardiac Function between Dual Chamber Pacing and Left Bundle Branch Regional Pacing

Clinical Comparison of Cardiac Function between Dual Chamber Pacing and Left Bundle Branch Regional Pacing