Conduction Time Research Articles

PO-05-226 ORTHODROMIC RECIPROCATING TACHYCARDIA RELYING ON ABERRANT CONDUCTION: NEED FOR A LAGER CIRCUIT

Aberrant conduction during orthodromic reciprocating tachycardia (ORT) can prolong the ventriculo-atrial conduction time, which is found essential for the reentry in certain situations. To investigate the prevalence and different mechanism of aberrancy-dependent ORT. ORT cases relying on aberrancy from 220 cases in our center were searched using the following criteria: (1) Multiple episodes of ORT with aberrant conduction in ECG ; (2) No baseline BBB during sinus rhythm; (3) Absence of narrow QRS form during tachycardia unless isoproterenol used; (4) Restoration of bundle branch conduction giving rise to tachycardia termination or circuit alteration. ECGs and intracardiac tracings during study were carefully examined. 3 patients from 220 patients (1.4%) with ORT showed the phenomenon of dependence on aberrancy. Clinical tachycardia episodes of the patients were short in time. All accessory pathways (APs) were located at anterolateral regions of atrioventricular annulus. None of them had baseline bundle branch block. Creating functional bundle branch block was necessary to induce the tachycardias. In the first patient with ORT and left bundle branch block (LBBB), a late-delivered premature ventricular contraction (PVC) was able to advance the next A and reset the tachycardia, which was diagnostic for ORT with aberrancy. Meanwhile, left bundle branch conduction was restored which narrowed the next QRS complex. Tachycardia was then terminated by the advanced wavefront reaching the ventricular insertion site of AP which was refractory. In the second case, termination of the tachycardia was always preceded by a spontaneous LBBB restoration, with the V and subsequent A at MA advanced, suggesting anterograde block in the AV node. In the other case was, induction required both right BBB and slow pathway conduction. When isoproterenol was given, fast pathway recovered followed by BBB restoration, which made anterograde limb again switched to slow pathway. All pathways were successfully ablated during the procedure. All patients have been free of arrhythmias for at least 6 months. Extra transseptal time caused by aberrancy can be an integral part of ORT, which can explain the infrequent or late onset and unsustainable episodes of ORT in certain patients and is useful in understanding the circuit and localizing the pathway.

The Transcallosal Highway: The ipsilateral silent period as a neural biomarker for impaired corpus callosum communication in multiple sclerosis

Multiple sclerosis is a neurodegenerative disease that damages myelin sheath within the central nervous system. This axonal demyelination impacts communication between the brain's hemispheres in persons with multiple sclerosis (PwMS). Changes in transcallosal communication impairs the coordination of movements requiring precise temporal and spatial components such as lower extremity function during gait. These bilateral movements require constant communication across the corpus callosum to excite and inhibit specific muscle groups. The ipsilateral silent period (iSP) is an indirect marker of the magnitude for transcallosal inhibition. We hypothesize that the iSP may also serve as a neural biomarker for transcallosal impairments originating from the more affected hemisphere and highlight underlying mechanisms for gait asymmetries in PwMS. Our ongoing study utilizes transcranial magnetic stimulation to assess the inhibitory capacity between the brain's hemispheres (i.e., iSPs). A focal magnetic pulse is delivered to the first dorsal interosseous resulting in a suppression of muscle activity, thus reflecting inhibitory transcallosal communication. There is a lack of research analyzing directionality data between the more and less affected hemisphere in PwMS. Therefore, we evaluate outcome metrics dependent upon the individual's more affected hemisphere. Twenty-three PwMS completed the ongoing protocol and inhibitory metrics such as depth iSP% average, duration, depth iSP% max, transcallosal conduction time, and onset latency were collected. No statistically significant differences have been found between the two hemispheres in PwMS. However, beyond directionality data, our study is investigating gait coordination with overall inhibitory capacity. Walking coordination is quantified using a metric called phase coordination index (PCI). A greater PCI value reflects poorer gait coordination. We hypothesize those who demonstrate better gait coordination (lower PCI values), will have a greater iSP. These findings will determine the potential of iSPs as a neural biomarker to address gait asymmetries and stratify participants into individualized mobility rehabilitation protocols. Multiple sclerosis is a neurodegenerative disease that damages myelin sheath within the central nervous system. This axonal demyelination impacts communication between the brain's hemispheres in persons with multiple sclerosis (PwMS). Changes in transcallosal communication impairs the coordination of movements requiring precise temporal and spatial components such as lower extremity function during gait. These bilateral movements require constant communication across the corpus callosum to excite and inhibit specific muscle groups. The ipsilateral silent period (iSP) is an indirect marker of the magnitude for transcallosal inhibition. We hypothesize that the iSP may also serve as a neural biomarker for transcallosal impairments originating from the more affected hemisphere and highlight underlying mechanisms for gait asymmetries in PwMS. Our ongoing study utilizes transcranial magnetic stimulation to assess the inhibitory capacity between the brain's hemispheres (i.e., iSPs). A focal magnetic pulse is delivered to the first dorsal interosseous resulting in a suppression of muscle activity, thus reflecting inhibitory transcallosal communication. There is a lack of research analyzing directionality data between the more and less affected hemisphere in PwMS. Therefore, we evaluate outcome metrics dependent upon the individual's more affected hemisphere. Twenty-three PwMS completed the ongoing protocol and inhibitory metrics such as depth iSP% average, duration, depth iSP% max, transcallosal conduction time, and onset latency were collected. No statistically significant differences have been found between the two hemispheres in PwMS. However, beyond directionality data, our study is investigating gait coordination with overall inhibitory capacity. Walking coordination is quantified using a metric called phase coordination index (PCI). A greater PCI value reflects poorer gait coordination. We hypothesize those who demonstrate better gait coordination (lower PCI values), will have a greater iSP. These findings will determine the potential of iSPs as a neural biomarker to address gait asymmetries and stratify participants into individualized mobility rehabilitation protocols.

Electrophysiological evidence of diabetes' impacts on central conduction recoveries in degenerative cervical myelopathy after surgery.

To assess the impact of diabetes mellitus (DM) on the postoperative motor and somatosensory functional recoveries of degenerative cervical myelopathy (DCM) patients. Motor and somatosensory evoked potentials (MEP and SSEPs) and modified Japanese Orthopedic Association (mJOA) scores were recorded in 27 diabetic (DCM-DM group) and 38 non-diabetic DCM patients (DCM group) before and 1 year after surgery. The central motor (CMCT) and somatosensory (CSCT) conduction time were recorded to evaluate the conductive functions of the spinal cord. The mJOA scores, CMCT and CSCT improved (t test, p < 0.05) in both of the DCM-DM and DCM groups 1year after surgery. The mJOA recovery rate (RR) and CSCT recovery ratio were significantly worse (t test, p < 0.05) in the DCM-DM group compared to the DCM group. DM proved to be a significant independent risk factor for poor CSCT recovery (OR = 4.52, 95% CI 2.32-7.12) after adjusting for possible confounding factors. In DCM-DM group, CSCT recovery ratio was also correlated with preoperative HbA1 level (R = - 0.55, p = 0.003). Furthermore, DM duration longer than 10years and insulin dependence were risk factors for lower mJOA, CMCT and CSCT recoveries among all DCM-DM patients (t test, p < 0.05). DM may directly hinders spinal cord conduction recovery in DCM patients after surgery. Corticospinal tract impairments are similar between DCM and DCM-DM patients, but significantly worsened in chronic or insulin-dependent DM patients. The dorsal column is more sensitively affected in all DCM-DM patients. Deeper investigation into the mechanisms and neural regeneration strategies is needed.

Does Forward Head Posture Influence Somatosensory Evoked Potentials and Somatosensory Processing in Asymptomatic Young Adults?

The current investigation used somatosensory evoked potentials (SEPs) to assess differences in sensorimotor integration and somatosensory processing variables between asymptomatic individuals with and without forward head posture (FHP). We assessed different neural regions of the somatosensory pathway, including the amplitudes of the peripheral N9, spinal N13, brainstem P14, peak-to-peak amplitudes of parietal N20 and P27, and frontal N30 potentials. Central conduction time (N13-N20) was measured as the difference in peak latencies of N13 and N20. We measured these variables in 60 participants with FHP defined as a craniovertebral angle (CVA) < 50° and 60 control participants matched for age, gender, and body mass index (BMI) with normal FHP defined as CVA > 55°. Differences in variable measures were examined using the parametric t-test. Pearson's correlation was used to evaluate the relationship between the CVA and sensorimotor integration and SEP measurements. A generalized linear model (GLM) was used to compare the SEP measures between groups, with adjustment for educational level, marital status, BMI, and working hours per week. There were statistically significant differences between the FHP group and control group for all sensorimotor integration and SEP processing variables, including the amplitudes of spinal N13 (p < 0.005), brainstem P14 (p < 0.005), peak-to-peak amplitudes of parietal N20 and P27 (p < 0.005), frontal N30 potentials (p < 0.005), and the conduction time N13-N20 (p = 0.004). The CVA significantly correlated with all measured neurophysiological variables indicating that as FHP increased, sensorimotor integration and SEP processing became less efficient. FHP group correlations were: N9 (r = -0.44, p < 0.001); N13 (r = -0.67, p < 0.001); P14 (r = -0.58, p < 0.001); N20 (r = -0.49, p = 0.001); P27 (r = -0.58, p < 0.001); N30 potentials (r = -0.64, p < 0.001); and N13-N20 (r = -0.61, p < 0.001). GLM identified that increased working hours adversely affected the SEP measures (p < 0.005), while each 1° increase in the CVA was associated with improved SEP amplitudes and more efficient central conduction time (N13-N20; p < 0.005). Less efficient sensorimotor integration and SEP processing may be related to previous scientific reports of altered sensorimotor control and athletic skill measures in populations with FHP. Future investigations should seek to replicate our findings in different spine disorders and symptomatic populations in an effort to understand how improving forward head posture might benefit functional outcomes of patient care.

Lateral, Optically Controlled, Artificial Synapses Realized in Room-Temperature RF-Sputtered SnO2 for Neuromorphic Computing and Visual Recognition

Volatile lateral memristors fabricated from amorphous SnO2 have exhibited synaptic properties including conductance modulation that depended on the number, width, and amplitude of voltage pulses within a sequence. Similar systematic conductance modulation was achieved using incident pulsed (UVC) light. By combining light and voltage pulses, OR/AND logic functions were implemented using single devices. Measurements performed in either N2 or air suggested that the device conductance, response, and decay times were affected by surface water chemisorption. Importantly, the aforementioned device functions were reliably demonstrated irrespective of this interaction with the ambient. Finally, simulations were performed to show that when placed in a suitable array, the measured device characteristics and responses to optical signals could enable hand-written digit recognition with accuracy exceeding 90%.

Optical and Electronic Properties of colloidal Cadmium Sulfide

Cadmium sulfide (CdS) is prepared with an easy and cost-effective method like the chemical route method. In the preparation method, there are 6-different types of CdS nanoparticles prepared using the capping agent. In this paper, while discussing the optical and electronic properties of cadmium sulfide (CdS), more emphasis has been laid on why you can use it over solar cells and photodetectors. Based on UV–visible spectroscopy band gaps for 6-different CdS types are measured, which shows that as the size of the CdS particle increases, their band gap increases. The nano size of 6 different CdS particles has been studied through the images obtained from the transmission electron microscope (TEM). CdS are classified as a semiconductor, so the electronic and electrical properties of CdS are also taken care of. In electronic properties, the electrical conductivity, resistivity, electron concentration, and collision times of CdS are calculated based on the data obtained from standard I (current)-V (voltage)-characteristics and bode plots. Based on the optical and electronic properties, the first three CdS types (CdS type-a, type-b, and type-c) are the best semiconductors compared to the rest of the CdS types. Therefore, these three CdS types can be used for the applications of solar cells and photodetectors.

The effects of combination treatment with LT4 and LT3 on diastolic functions and atrial conduction time in LT4-treated women with low T3: a short term follow-up study.

To investigate the effects of combination treatment with levothyroxine (LT4) and l- triiodothyronine (LT3) on left atrial volume (LAV), diastolic functions, and atrial electro-mechanical delays in LT4-treated women with low triiodothyronine (T3) levels. This prospective study consisted of 47 female patients between 18 and 65 years old treated at an Endocrinology and Metabolism outpatient clinic between February and April 2022 due to primary hypothyroidism. The study included patients with persistently low T3 levels in at least three measurements, despite LT4 treatment (1.6-1.8 mcg/kg/m2) for 23.13 ± 6.28 months with normal thyrotropin (TSH) and free tetraiodothyronine (fT4) levels. The combination therapy dose was as follows: the fixed LT4 dose (25 mcg) was removed from patients' usual LT4 treatment [100 mcg (min-max, 75-150)], and a fixed LT3 dose (12.5 mcg) was added. Biochemical samples were taken, and an echocardiographic assessment was performed for patients upon their first admission, and after 195.5 ± 12.8 days of receiving LT3 (12.5 mcg) treatment. There was a statistically significant reduction at left ventricle (LV) end-systolic diameter (27.69 ± 3.14, 27.13 ± 2.89, p = 0.035), left atrial (LA) maximum volume (14.73 ± 3.22, 13.94 ± 3.15, p = 0.009), LA minimum volume (7.84 ± 2.45, 6.84 ± 2.30, p < 0.001), LA vertical diameter (44.08 ± 6.92, 34.60 ± 4.31, <0.001), LA horizontal diameter (45.65 ± 6.88, 33.43 ± 4.51, p < 0.001), LAVI (50.73 ± 18.62, 41.0 ± 13.02, p < 0.001), total conduction time (103.69 ± 12.70, 79.82 ± 18.40, p < 0.001) after LT3 replacement (respectively pre-post- treatment and p value). In conclusion, the findings of this study suggest that the addition of LT3 to LT4 treatment may lead to improvements in LAVI and atrial conduction times in patients with low T3. However, further research with larger patient groups and exploration of different LT4 + LT3 dose combinations is needed to better understand the effects of combined hypothyroidism treatment on cardiac functions.

Role of Crystal Structure on the Ionic Conduction and Electrical Properties of Germanate Compounds A2Cu3Ge4O12 (A = Na, K)

Crystal structure and electrical properties of A2Cu3Ge4O12 (where A = Na, K) have been investigated by neutron diffraction and electrical impedance spectroscopy (EIS). The real and imaginary parts of the impedance, dielectric constant, and electrical modulus have been studied as a function of frequency and temperature. The crystal structures of the compounds K2Cu3Ge4O12 (KCGO) and Na2Cu3Ge4O12 (NCGO) are made of perfect 2D and quasi-2D alkali metal ion layers, respectively. The dc conductivity occurs due to small polaron hopping for both compounds with single activation energy over the entire experimentally available temperature range. The values of activation energies are 0.90(3) and 1.22(6) eV for KCGO and NCGO, respectively, as determined from dc conductivity and relaxation time analysis. The frequency dependent ac conductivity curves for both compounds follow a universal Jonscher’s power law. Soft bond valence sum analysis of neutron diffraction data reveals that the conduction pathways are confined within a plane in KCGO, whereas they form a one-dimensional channel in NCGO. The bottlenecks for ionic conduction and the role of crystal structure on them are discussed. The scaling behavior of electrical modulus indicates that the relaxation process does not change with temperature; however, a sharp decrease in the time constant has been observed. The present comprehensive study facilitates the understanding of the role of crystal structure on the microscopic mechanism of ionic conduction in both battery materials, which would be useful in designing sodium and potassium based ionic conductors. Further, the constant value of activation energy over the kHz frequency range is suitable for potential applications of the studied materials in avalanche beacons and amateur and geophysical sensors.

Differentiating Neurodegenerative Disease From Compressive Cervical Myelopathy Using Motor-Evoked Potentials.

A retrospective case-control study. To differentiate neurodegenerative diseases from compressive cervical myelopathy (CCM) using motor-evoked potentials (MEPs). When considering surgery for CCM, it may be necessary to differentiate the condition from a neurodegenerative disease. A total of 30 healthy volunteers, 52 typical CCM patients with single-level compression of the spinal cord at C4-5 or C5-6, 7 patients with amyotrophic lateral sclerosis (ALS), and 12 patients with demyelinating disease of the central nervous system, including 11 patients with multiple sclerosis and 1 patient with neuromyelitis optica spectrum disorder, formed our study population. MEPs were recorded from the bilateral abductor digiti minimi (ADM) and abductor hallucis (AH) muscles using transcranial magnetic stimulation and electrical stimulation of the ulnar and tibial nerves. Central motor conduction time, peripheral conduction time, amplitude of MEPs, and frequency of F waves were evaluated. Receiver operating characteristic curve analysis was used to determine the cutoff value for distinguishing between CCM and ALS. Significant differences were observed in the amplitude of MEPs and frequency of F waves evoked by peripheral nerve stimulation between patients with CCM and ALS. The MEP amplitude of AH was more accurate in differentiating between the two diseases compared with ADM (cutoff value, 11.2 mV, sensitivity, 87.5%; specificity, 85.7%). All 7 patients with ALS showed reduced frequency of F waves from ADM or AH, but none of the healthy volunteers or patients with other diseases demonstrated this finding. Moreover, there were no significant differences between CCM and demyelinating disease of the central nervous system in any of the assessments. The amplitude of MEPs and frequency of F waves evoked by peripheral nerve stimulation could be helpful in differentiating ALS from CCM.

A Novel Variable On-Time Control Scheme for Boundary Conduction Mode SEPIC PFC Converter

Power factor correction (PFC) can be achieved by a single-ended primary inductor converter (SEPIC) operating in boundary conduction mode (BCM) with conventional constant on-time (COT) control, but it is challenging to achieve low total harmonic distortion (THD) and high-power factor (PF), particularly at high input voltage. A variable on-time (VOT) control strategy for BCM SEPIC PFC converter without input voltage feedforward and multiplier circuits is proposed to realize unity PF in this paper. By using a variable slope sawtooth generator whose slope is controlled by the duty cycle of the main switch to adjust the conduction time of the main power switch of the converter, the proposed VOT control scheme can use a simple and easy-to-implement circuit to enhance the PF and decrease the THD significantly, especially at high input voltage. The simulation model and 100W experimental prototype are built to verify the feasibility of the suggested control method. Simulation and experiment results demonstrated that the novel VOT control scheme remarkably enhances PF and decreases THD without affecting the efficiency by contrast with the conventional COT control.

The impact of chronotropic incompetence on atrioventricular conduction times in heart failure patients.

Intrinsic atrioventricular (AV) conduction is used to optimize AV intervals with cardiac resynchronization therapy (CRT) in most device algorithms. Atrial pacing and heart rate affect conduction times, but little is known regarding differeces among chronotropic incompetent(CI) and competent(CC) patients to guide programming. RAVE was a multicenter prospective trial of CRT patients. Heart rate was increased with incremental atrial pacing and with submaximal exercise. According to the maximal heart rate achieved during exercise, patients were classified as either CI or CC. For CI patients, an additional symptom-limited exercise with rate-adaptive pacing activated was performed. Intracardiac intervals were measured from the implantable lead electrograms in multiple postures. There were 12 subjects with CI and 24 with CC. With atrial pacing, AV interval immediately increased and gradually increased with incremental atrial pacing in all patients. However, the changes in the atrial to right ventricular (ARV) and atrial to left ventricular (ALV) intervals with increasing atrial pacing rates were about threefold greater in CI patients compared to CC patients (24.3 ± 28.9 vs. 7.2 ± 5.5ms/10bpm for ARV and 22.7 ± 25.6 vs. 7.1 ± 5.7ms/10bpm for ALV in the standing position, p < 0.05). In CI pacing with rate-adaptive pacing during exercise, AV interval changes with paced heart rate were variable. The AV response to overdrive atrial pacing at rest may provide a simple means of identifying chronotropic competence in CRT patients. For patients with CI, who often require rate-adaptive atrial pacing, rate-adaptive AV algorithms should be adjusted individually.

Effectiveness of the repurposed drug isotretinoin in an experimental murine model of Chagas disease

Benznidazole and nifurtimox are the drugs currently used for the treatment of Chagas disease, however its side effects may affect patient adherence. In the search for new alternative therapies, we previously identified isotretinoin (ISO), an FDA-approved drug widely used for the treatment of severe acne through a drug repurposing strategy. ISO shows a strong activity against Trypanosoma cruzi parasites in the nanomolar range, and its mechanism of action is through the inhibition of T. cruzi polyamine and amino acid transporters from the Amino Acid/Auxin Permeases (AAAP) family. In this work, a murine model of chronic Chagas disease (C57BL/6 J mice), intraperitoneally infected with T. cruzi Nicaragua isolate (DTU TcI), were treated with different oral administrations of ISO: daily doses of 5 mg/kg/day for 30 days and weekly doses of 10 mg/kg during 13 weeks. The efficacy of the treatments was evaluated by monitoring blood parasitemia by qPCR, anti-T. cruzi antibodies by ELISA, and cardiac abnormalities by electrocardiography. No parasites were detected in blood after any of the ISO treatments. The electrocardiographic study of the untreated chronic mice showed a significant decrease in heart rate, while in the treated mice this negative chronotropic effect was not observed. Atrioventricular nodal conduction time in untreated mice was significantly longer than in treated animals. Mice treated even with ISO 10 mg/kg dose every 7 days, showed a significant reduction in anti-T. cruzi IgG levels. In conclusion, the intermittent administration of ISO 10 mg/kg would improve myocardial compromise during the chronic stage.

A Line Cycle Synchronous Rectification Strategy Based on Time-Domain Analysis for Single- Stage AC–DC LLC Converters

Synchronous rectification that is being widely used in high power and current DC-DC <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converters to reduce conduction losses can be challenging in single-stage AC-DC <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> converters with high output voltage levels (i.e., >200 V) where synchronous rectifier (SR) driving ICs cannot be used. In this paper, a simple AC line cycle synchronous rectification strategy with direct control by a cost-effective microcontroller unit (MCU) is proposed for single-stage AC-DC <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> converters with high switching frequencies using wide bandgap devices (i.e., GaN or SiC). The SR gate pulse is generated based on the time-domain calculated conduction time, which is then switched <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> and <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> over the AC line cycle to avoid reverse power flow in light load conditions. The proposed strategy reduces the complexity of implementation over any adaptive online calculation or model-based methods that require powerful and expensive MCUs. First, the operation is briefly described followed by the time-domain analysis for AC operation. Next, the calculation and methodology behind the proposed AC line cycle SR driving strategy are discussed in detail. A scaled-down wide bandgap-based AC-DC <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> converter prototype with a 250--400 V output voltage range is used with digital control implementation to validate the performance of the proposed synchronous rectification strategy. It is found that maximum efficiency of 98.1% can be achieved which is improved by around 0.5% over the conventional fixed conduction time method. Moreover, it is shown that the proposed method obtains the same efficiency levels as more complex adaptive SR driving approaches.

Investigation of the metal–semiconductor interface by equivalent circuit model in zinc phthalocyanine (ZnPc) based Schottky diodes and its charge transport properties

In this report, the ZnPc-based metal–semiconductor (MS) junction Schottky devices (Al/ZnPc/ITO) were fabricated using an effusion cell coating unit. To study the formation of the MS junction, the surface morphology of the deposited ZnPc thin film was investigated using field-emission scanning electron microscope (FESEM) images. The interfacial properties of the MS junction of the Al/ZnPc/ITO configuration were studied using the ac impedance spectroscopy technique within the frequency range of 50 Hz–10 MHz at room temperature (300 K). The bias-dependent impedance spectroscopy was carried out within the voltage range of ±1 V to establish the equivalent circuit of the MS junction Schottky diodes (SDs). The current vs. voltage (I-V) measurements of the fabricated SDs were also conducted to deduce the diode parameters, namely on/off ratio, photosensitivity, ideality factor, barrier height, and series resistance. The charge transport parameters including dc conductivity, mobility and transit time of the charge carriers were also estimated employing the spatial-charge limited current (SCLC) theory, which illustrates the enhanced carrier’s mobility and consequently, the device performance after light irradiation.

Decolorisation of Reactive Congo Red Dye Solution by Electro Coagulation Process

The decolourisation of the reactive Congo red dye from synthetic wastewater was studied using ElectroCoagulation (EC) technique. In an effort to increase removal efficiency, the effects of operating parameters including flow, inter electrode distance, conductivity, voltage, and Hydraulic Detention Time (HDT) were investigated. An electrochemical cell was initially created with an aluminum cathode and anode. Following that, each variable's impact was examined independently using synthetic wastewater. The colour removal efficiency was 93% when the initial dye concentration was 4 mg/L, the conductivity was 300 ppm, the temperature was 24 oC, the interelectrode spacing was 1 cm, and the HDT of the electrolysis was 120 min.

Behavior of Retrograde Conduction Time at Supraventricular Tachycardia Induction and its Role in Differential Diagnosis

Background: Differential diagnosis between orthodromic reentrant tachycardia (ORT) and atypical nodal reentrant tachycardia (ANRT) can be challenging. Our hypothesis was that ANRT presents more variability in retrograde conduction time at tachycardia onset than ORT. Objectives: The objectives of this study were to assess retrograde conduction time variability at the start of tachycardia in ANRT and ORT, and postulate a new diagnostic tool to differentiate these two types of arrhythmias. Methods: The ventriculoatrial (VA) interval of the first beats after tachycardia induction was measured until stabilization. The difference between the maximum and minimum VA interval was defined as delta VA (ΔVA), and the number of beats needed for VA interval stabilization was also assessed. Atrial tachycardias were excluded. Results: In a total of 101 patients included in the study, ORT was diagnosed in 64 patients and ANRT in 37. ΔVA interval was 0 (interquartile range [IQR] 0-5) milliseconds (ms) in ORT vs. 40 (21-55) ms in ANRT (p &lt;0.001). The VA interval significantly stabilized earlier in ORT (1.5 [1-3] beats) than in ANRT (5 [4-7] beats) (p&lt;0.001). A ΔVA &lt;10 ms diagnosed ORT with 100% sensitivity, specificity, and positive and negative predictive values. Ventriculoatrial interval stabilization in less than 3 beats predicted ORT with good diagnostic accuracy. The results were similar considering only accessory septal pathways. Typical NRTs presented an intermediate variation. Conclusion: Presence of ΔVA &lt;10 ms is a simple criterion that accurately differentiates ORT from ANRT, independently of the accessory pathway localization.

Shortened neural conduction time in young adults with tinnitus as revealed by chirp-evoked auditory brainstem response

Tinnitus is generally considered to be caused by neuroplastic changes in the central nervous system, triggered by a loss of input from the damaged peripheral system; however, conflicting results on auditory brainstem responses (ABRs) to clicks have been reported previously in humans with tinnitus. This study aimed to compare the effect of tinnitus on ABRs to chirps with those to clicks in normal-hearing young adults with tinnitus. The results showed that the tinnitus group had no significantly poorer hearing thresholds (0.25-16 kHz), click-evoked otoacoustic emissions (1-16 kHz), and speech perception in noise (SPIN) than the control group. Although chirps evoked significantly larger wave I and V amplitudes than clicks, people with tinnitus had no significantly smaller wave I amplitudes for either stimulus. Nevertheless, adults with tinnitus exhibited significantly smaller interpeak interval (IPI) between waves I and V for chirps (IPI-chirp) but not for clicks. In addition, the IPI-chirp correlated significantly with the SPIN for individuals with tinnitus when the signal-to-noise ratio was low. The present results suggest that the chirp-evoked ABR may be a valuable clinical tool for objectively assessing the SPIN in individuals with tinnitus. Further studies should be conducted to investigate possible etiologies of tinnitus.

Electro-Mechanical Alterations in Atrial Fibrillation: Structural, Electrical, and Functional Correlates.

Atrial fibrillation is the most common arrhythmia encountered in clinical practice affecting both patients' survival and well-being. Apart from aging, many cardiovascular risk factors may cause structural remodeling of the atrial myocardium leading to atrial fibrillation development. Structural remodelling refers to the development of atrial fibrosis, as well as to alterations in atrial size and cellular ultrastructure. The latter includes myolysis, the development of glycogen accumulation, altered Connexin expression, subcellular changes, and sinus rhythm alterations. The structural remodeling of the atrial myocardium is commonly associated with the presence of interatrial block. On the other hand, prolongation of the interatrial conduction time is encountered when atrial pressure is acutely increased. Electrical correlates of conduction disturbances include alterations in P wave parameters, such as partial or advanced interatrial block, alterations in P wave axis, voltage, area, morphology, or abnormal electrophysiological characteristics, such as alterations in bipolar or unipolar voltage mapping, electrogram fractionation, endo-epicardial asynchrony of the atrial wall, or slower cardiac conduction velocity. Functional correlates of conduction disturbances may incorporate alterations in left atrial diameter, volume, or strain. Echocardiography or cardiac magnetic resonance imaging (MRI) is commonly used to assess these parameters. Finally, the echocardiography-derived total atrial conduction time (PA-TDI duration) may reflect both atrial electrical and structural alterations.

Interatrial blocks in patients with tavi and their associations with clinic parameters

Aims: The present study attempted to evaluate the prevalence of basal interatrial blocks (IABs), their associations with clinical parameters, and the interatrial conduction in the follow-up after a successful transcatheter aortic valve implantation (TAVI) procedure among patients with severe aortic stenosis. Methods: We retrospectively evaluated the findings of 90 patients undergoing TAVI in our center. Overall, we considered the presence and grades of IABs and P-wave durations in electrocardiograms (ECG), preoperative echocardiography (ECHO) findings (maximum and mean gradients and left atrium (LA) diameter), valve size and type, and changes in these parameters at sixth month. Results: Forty-six patients were included in the study which are suitable for the pre-determined inclusion criteria. We found the mean age of the patients to be 74.78 ± 8.66 years. In preoperatively-evaluated ECGs, while we detected partial IABs in 37% of the patients, there were advanced IABs in 6.5%, but 56.5% yielded no interatrial conduction disorder. On the other hand, in postoperatively-evaluated ECGs, while we observed partial IABs in 30.4% of the patients, there were advanced IABs among 21.7% (p = 0.017). Nevertheless, we could not conclude any IABs among 47.8% of the patients. Besides, 54.3% of the patients received a self-expandable valve, and a balloon-expandable valve was inserted in 45.7%. In this regard, we detected partial (7 patients) and advanced (2 patients) IABs in the preoperatively-evaluated ECGs of the patients receiving a self-expandable valve. In the postoperative ECGs of these patients, while the partial IAB remained the same in 4 patients (57.1%), it progressed to an advanced IAB in 3 (42.9%). In addition, while the advanced IAB regressed to a partial IAB in one patient, it remained the same for the other patient. In this group, the mean P-wave durations were found to be 118.4±22.67 before the TAVI and 119.6±21.69 after the TAVI (p = 0.113). In the preoperative ECGs of 21 patients with a balloon-expandable valve, we detected partial IABs in 10 patients and an advanced IAB in one patient. While a partial IAB developed in five patients (p = 0.022), five patients with a partial IAB developed an advanced IAB following the procedure (p = 0.022). In this group, we noticed a significant difference between preoperative (127.62±19.4) and postoperative (138.71+ 32.03) P-wave durations (p = 0.038). Conclusion: In a nutshell, we concluded no significant change in interatrial conduction time of the patients with TAVI compared to the baseline in their sixth-month ECGs. When considered by valve type, we concluded that the development and progression of IABs were significant among those with a balloon-expandable valve. The higher postoperative mean gradient among those with a balloon-expandable valve compared to those with a self-expandable valve may be associated with significantly longer P-wave duration among those with a balloon-expandable valve.

Oligodendrocyte-mediated myelin plasticity and its role in neural synchronization.

Temporal synchrony of signals arriving from different neurons or brain regions is essential for proper neural processing. Nevertheless, it is not well understood how such synchrony is achieved and maintained in a complex network of time-delayed neural interactions. Myelin plasticity, accomplished by oligodendrocytes (OLs), has been suggested as an efficient mechanism for controlling timing in brain communications through adaptive changes of axonal conduction velocity and consequently conduction time delays, or latencies; however, local rules and feedback mechanisms that OLs use to achieve synchronization are not known. We propose a mathematical model of oligodendrocyte-mediated myelin plasticity (OMP) in which OLs play an active role in providing such feedback. This is achieved without using arrival times at the synapse or modulatory signaling from astrocytes; instead, it relies on the presence of global and transient OL responses to local action potentials in the axons they myelinate. While inspired by OL morphology, we provide the theoretical underpinnings that motivated the model and explore its performance for a wide range of its parameters. Our results indicate that when the characteristic time of OL's transient intracellular responses to neural spikes is between 10 and 40 ms and the firing rates in individual axons are relatively low (10 Hz), the OMP model efficiently synchronizes correlated and time-locked signals while latencies in axons carrying independent signals are unaffected. This suggests a novel form of selective synchronization in the CNS in which oligodendrocytes play an active role by modulating the conduction delays of correlated spike trains as they traverse to their targets.