Residual Conductivity Research Articles

Electric and dielectric properties of copper-chromium layered double hydroxide intercalated with chloride ion using impedance spectroscopy

ABSTRACTThe aim of this work is the study of dielectric and electrical performance of a dielectric anionic clay based on copper and chromium, and intercalated by chloride ions. Dielectric was synthesized by soft chemistry using the coprecipitation method at room temperature. The analysis of physicochemical properties of the material is performed by X-ray diffraction, Fourier transform-infrared, thermogravimetric analysis, and inductively coupled plasma.As for the dielectric response, it was performed using the dielectric impedance spectroscopy. Two relaxation modes were detected at the Nyquist diagrams. Modelization with equivalent circuit allowed us to determinate intrinsic electrical parameters of the dielectric (resistance, capacity) corresponding to the two contributions. The evolution of the dielectric constant with the frequency gave values comparable to the dielectrics. Finally, an adjustment according to Jonscher law was developed to determine the value of residual conductivity generally present in dielectrics, also called dc conductivity.

Clinical and Genetic Spectrum of Bartter Syndrome Type 3

Bartter syndrome type 3 is a clinically heterogeneous hereditary salt-losing tubulopathy caused by mutations of the chloride voltage-gated channel Kb gene (CLCNKB), which encodes the ClC-Kb chloride channel involved in NaCl reabsorption in the renal tubule. To study phenotype/genotype correlations, we performed genetic analyses by direct sequencing and multiplex ligation-dependent probe amplification and retrospectively analyzed medical charts for 115 patients with CLCNKB mutations. Functional analyses were performed in Xenopus laevis oocytes for eight missense and two nonsense mutations. We detected 60 mutations, including 27 previously unreported mutations. Among patients, 29.5% had a phenotype of ante/neonatal Bartter syndrome (polyhydramnios or diagnosis in the first month of life), 44.5% had classic Bartter syndrome (diagnosis during childhood, hypercalciuria, and/or polyuria), and 26.0% had Gitelman-like syndrome (fortuitous discovery of hypokalemia with hypomagnesemia and/or hypocalciuria in childhood or adulthood). Nine of the ten mutations expressed in vitro decreased or abolished chloride conductance. Severe (large deletions, frameshift, nonsense, and essential splicing) and missense mutations resulting in poor residual conductance were associated with younger age at diagnosis. Electrolyte supplements and indomethacin were used frequently to induce catch-up growth, with few adverse effects. After a median follow-up of 8 (range, 1-41) years in 77 patients, chronic renal failure was detected in 19 patients (25%): one required hemodialysis and four underwent renal transplant. In summary, we report a genotype/phenotype correlation for Bartter syndrome type 3: complete loss-of-function mutations associated with younger age at diagnosis, and CKD was observed in all phenotypes.

Highly Insulating Polyethylene Blends for High-Voltage Direct-Current Power Cables

The insulation of state-of-the-art extruded high-voltage direct-current (HVDC) power cables is composed of cross-linked low-density polyethylene. Driven by the search for sustainable energy solutions, concepts that improve the ability to withstand high electrical fields and, ultimately, the power transmission efficiency are in high demand. The performance of a HVDC insulation material is limited by its residual electrical conductivity. Here, we demonstrate that the addition of small amounts of high-density polyethylene (HDPE) to a low-density polyethylene (LDPE) resin results in a drastic reduction in DC conductivity. An HDPE content as low as 1 wt % is found to introduce a small population of thicker crystalline lamellae, which are finely distributed throughout the material. The change in nanostructure correlates with a decrease in DC conductivity by approximately 1 order of magnitude to about 10-15 S m-1 at high electric fields of 30 and 40 kV mm-1 and elevated temperature of 70 °C. This work opens up an alternative design concept for the insulation of HVDC power cables.

Irrigation and Drinking Water Quality Index Determination for Groundwater Quality Evaluation in Akoko Northwest and Northeast Areas of Ondo State, Southwestern Nigeria

In order to understand the suitability of groundwater for drinking and irrigation purposes in Akoko northwest and Akoko northeast, water quality index calculation, % Na, Sodium Absorption Ratio (SAR), Residual Sodium Carbonate (RSC), Permeability Index (PI) and Electrical Conductivity were determined from thirteen water samples. The sequence of the abundance of the major ions is in the following order of K<SUP>+</SUP> &gt; Na<SUP>+</SUP> &gt; Ca<SUP>2+</SUP> &gt; Mg<SUP>2+</SUP> for cations and Cl<SUP>-</SUP> &gt; HCO<SUB>3</SUB><SUP>-</SUP> &gt; SO<SUB>4</SUB><SUP>-</SUP> &gt; F<SUP>-</SUP> in anions. The water quality index (WQI) obtained for the water samples ranges between 22.7 and 88.6. The water quality index classified the water into “excellent” and “good” drinking water and account for about 85% and 15% of the study area respectively. The % Na of the samples varies between 49 and 79%. Sodium Absorption Ratio (SAR) of the studied water samples varies from 1.40 to 3.56 with a mean of 2.44. The values are within 0 - 10 specified as excellent water for irrigation purpose. The Residual Sodium Carbonate (RSC) values ranges between – 51.6 and + 10.57, with an average of -14.5, which agrees with less than 2.5 specified for the purpose of irrigation. The permeability index (PI) of the water varies from 2.27 to 19.9, with an average of 7.93. The values fall within the Third category of 0 – 25 irrigation water which is rated as poor. The electrical conductivity of the water ranges from 117 to 789 μs/cm with an average of 378 μs/cm which corresponds to moderate (medium salinity). Also, the water in the study area shows variation of low salinity to high salinity. The Wilcox plot showed that the water samples have excellent – good irrigation potential except a sample taken from Arigidi Akoko which fall within “good to permissible limit.” Therefore combine all these results the water are moderately suitable for irrigation purpose and good for drinking.

Effect of High Temperature on Properties of Glass Concrete

In this study, the concrete is mixed with glass fibers which are 0.5%, 1.0% and 1.5% of cement weight and 0.6 cm long. The effect of fiber addition level on the compressive strength, bending strength and residual compressive strength and thermal conductivity after heating of concrete is discussed. The test results show that an appropriate addition of glass fiber to the concrete at room temperature is favorable for the compressive strength. A low addition of relatively short glass fiber has insignificant effect on the bending strength. However, the adverse effect on the bending strength will increase if the addition level is too high. The addition of glass fiber can improve the loss of concrete strength under the effect of high temperature not exceeding 500°C, and a relatively high compressive strength remains under the effect of high temperature not exceeding 800°C. The high temperature can reduce the thermal conductivity of glass concrete, and the higher the addition level of glass fiber is, the lower is the thermal conductivity. Keywords: Glass fiber, concrete, heating, thermal conductivity

Abstract 13127: Catheter Ablation of Atrial Fibrillation: Midterm Outcome of Radiofrequency Catheter Ablation for Redo Procedures After Pulmonary Vein Isolation With the Cryoballoon First Versus Second Generation Cryoballoon)

Introduction: Catheter ablation has become the first line of therapy in patients with symptomatic, recurrent, drug-refractory AF. Cryoablation has been shown to be a safe and effective technique for PV isolation. However, there is a significant arrhythmia recurrence rate after cryoablation procedures and there are no established strategies for redo procedures in these patients. Therefore, we have summarized our experience with radiofrequency catheter ablation for redo procedures after pulmonary vein isolation with the cryoballoon technique (ater procedures performed with the first or second generation cryoballoon). Hypothesis / Methods: Sixty patients had to undergo a redo procedure after initially successful circumferential PV isolation with the cryoballoon technique (Arctic Front Balloon, Medtronic: 30 patients (group A); Arctic Front Advance, Medtronic: 30 patients (group B)). The redo ablation procedures were performed using a segmental approach or a circumferential ablation strategy (CARTO) depending on the intra-procedural findings. Results: During the redo procedure, a mean number of 1.9 re-conducting PVs were detected (group A: 2.5 re-conducting PVs, group B: 1.3 re-conducting PVs). In 26 patients in group A, a segmental approach was sufficient to eliminate the residual PV conduction because there were only a few recovered PV fibers (1-3 reconnected PVs; group A1). In the remaining 4 patients in group A, a circumferential ablation strategy was used because of a complete recovery of the PV-LA conduction of all four PVs (group A2). In group B, a segmental approach was sufficient in all patients because there was only a minor reconnection of 1-2 PVs. All recovered PVs could be isolated sucessfully again. At 6-month follow-up, 80.0 % of all patients were free from an arrhythmia recurrence (48/60 patients; group A: 23/30 patients (76.7 %), group B: 25/30 patients (83.3 %)). Conclusions: In patients with an initial circumferential PVI using the cryoballoon technique, a repeat ablation procedure can be performed safely and effectively using RF catheter ablation. In most cases only a few re-conducting PV fibers were found and therefore, a segmental re-ablation approach seems to be sufficient in the majority of patients.

Weak antilocalization and linear magnetoresistance in the surface state ofSmB6

The strongly correlated Kondo insulator ${\mathrm{SmB}}_{6}$ is known for its peculiar low-temperature residual conduction, which has recently been demonstrated to arise from a robust metallic surface, as predicted by the theory of topological Kondo insulator (TKI). Photoemission, quantum oscillation, and magnetic doping experiments have provided evidence for the Dirac-like dispersion and topological protection. Questions arise as to whether signatures of spin-momentum locking and electron interaction could be resolved in transport measurements. Here we report metallic conduction of surface down to mK temperatures. We observe in the surface the weak-antilocalization (WAL) effect at small perpendicular magnetic fields. At larger perpendicular magnetic fields, the surface exhibits an unusual linear magnetoresistance similar to those found in Bi-based topological insulators and in graphene.

Long-Term Follow-Up After Catheter Ablation of Atrioventricular Nodal Reentrant Tachycardia in Children.

Catheter ablation of the slow conducting pathway (SP) is treatment of choice for atrioventricular nodal reentrant tachycardia (AVNRT). Although there are abundant data on AVNRT ablation in adult patients, little is known about the long-term results ≥3 years after AVNRT ablation in pediatric patients. Follow-up data from 241 patients aged ≤18 years who had undergone successful AVNRT ablation were analyzed. Median age at ablation had been 12.5 years, and median follow-up was 5.9 years. Radiofrequency current had been used in 168 patients (70%), whereas cryoenergy had been used in 73 patients (30%). Procedural end point of AVNRT ablation had been either SP ablation (no residual dual atrioventricular nodal physiology) or SP modulation (residual SP conduction allowing for a maximum of one atrial echo beat). After the initial AVNRT ablation, calculated freedom from AVNRT was 96% at 1 year, 94% at 3 years, 93% at 5 years, and 89% at 8 years. Age, sex, body weight, the choice of ablation energy, and the procedural end point of AVNRT ablation did not impact freedom from AVNRT. Six of 22 AVNRT recurrences (27%) occurred ≥5 years after ablation. No late complications including atrioventricular block were noted. Cumulatively, catheter ablation of AVNRT continued to be effective in >90% of our pediatric patients during the long-term course. A significant part of recurrences occurred >5 years post ablation. Body weight, energy source, and the end point of ablation had no impact on long-term results. No adverse sequelae were noted.

Anomalous three-dimensional bulk ac conduction within the Kondo gap of SmB6 single crystals

The Kondo insulator SmB$_6$ has long been known to display anomalous transport behavior at low temperatures, T$<5$ K. In this temperatures range, a plateau is observed in the dc resistivity, contrary to the exponential divergence expected for a gapped system. Recent theoretical calculations suggest that SmB$_6$ may be the first topological Kondo insulator (TKI) and propose that the residual conductivity is due to topological surface states which reside within the Kondo gap. Since the TKI prediction many experiments have claimed to observe high mobility surface states within a perfectly insulating hybridization gap. Here, we investigate the low energy optical conductivity within the hybridization gap of single crystals of SmB$_6$ via time domain terahertz spectroscopy. Samples grown by both optical floating zone and aluminum flux methods are investigated to probe for differences originating from sample growth techniques. We find that both samples display significant 3D bulk conduction originating within the Kondo gap. Although SmB$_6$ may be a bulk dc insulator, it shows significant bulk ac conduction that is many orders of magnitude larger than any known impurity band conduction. The nature of these in-gap states and their coupling with the low energy spin excitons of SmB$_6$ is discussed. Additionally, the well defined conduction path geometry of our optical experiments allows us to show that any surface states, which lie below our detection threshold if present, must have a sheet resistance of R$/\square \ge$ 1000 $\Omega$.

Cryoablation of atrioventricular nodal re-entrant tachycardia: 7-year follow-up in 515 patients—confirmed safety but very late recurrences occur

Cryoablation is an alternative method to radiofrequency ablation for treatment of atrioventricular nodal re-entrant tachycardia (AVNRT). This study investigates the long-term safety and efficacy of cryoablation in AVNRT. We studied 515 consecutive patients (317 women, mean age 50 years, range 13-89 years) undergoing a first cryoablation for AVNRT between 2003 and 2008. Ablations were performed with a 6-mm Freezor Xtra catheter. Six patients were acute failures; 494 out of 509 (97%) primarily successfully ablated patients were followed up for a mean of 7.1 years (range 2-12 years). About 11% (54/494 patients) of patients had recurrences of the index arrhythmia. Time to recurrence varied from days to 9 years; 14 patients (3%) had recurrences later than 2 years, 8 patients (2%) later than 3 years, and 6 patients (2%) later than 4 years. Recurrence rate was higher in patients with slow-slow or fast-slow AVNRT (n = 24) compared with the common slow-fast variant (25 vs. 10%; P = 0.04). Recurrence rate was not higher in patients with residual slow pathway conduction (jump with or without echo beat, n = 199, 39%). Transient atrioventricular (AV) block of the first-, second-, or third-degree during ablation was observed in 45 patients but had no impact on the risk of AVNRT recurrence. No late AV block occurred. Single vs. multiple applications or total amount of cryoenergy delivered did not differ between patients with and without recurrences. Cryoablation in AVNRT is safe with a long-term efficacy of 88%; however, very late recurrences occur.

Development and Optimization of Thin-Film Technology Based Micro Inductors and Transformers

In order to follow the current trends of electronic device development like miniaturization and increase of switching frequencies especially for magnetic passive components e.g. inductors and transformers innovative fabrication technology is expedient. In general switching frequencies in the range of 15 MHz to 50 MHz are intended. Some researcher teams focus on manufacturing micro transformer and inductors with thin-film technology in order to satisfy the market demands [1,2]. The design, the fabrication technology and the characteristics of the manufactured micro inductor and transformer were previous published. The 1st and 2nd generation were equipped with 4 contact pads on each side, primary and secondary side. The 5 µm thick soft magnetic closed oval core was deposited electrochemically. It consists of NiFe 80/20 [3] or CoFe 45/55 [4] and a multilayer coil with non-copper seed layer. The 3rd generation was equipped with 3 contact pads on each side and 10 µm [5] or 5 µm [6]thick electrochemically deposited CoFe 45/55 closed oval core with an electroplated multilayer coil with non-copper seed layers. The 4th generation of this solenoid-core transformer is developed and presented in this work. The dies have 3 contact pads on each side, 5 µm thick electroplated CoFe 45/55 core is enclosed in pure copper coils. The impetus to further development of the devices is the electrical and magnetic performance optimization. The process flow is modified in order to eliminate the interplies of chromium and gold -which were used as seed layers for electrochemical deposition of copper on copper. The 4th generation of the micro inductor and transformer with Electronic Industries Alliance Standard 1008 footprint is based on thin-film technology namely electrochemical deposition of copper and soft magnetic alloy CoFe 45/55 , physical vapour deposition, photolithography and encapsulating with copper compatible, photosensitive polyimide. The optimization of the process flow shows lower electrical resistance of the coils in comparison to earlier generations. Whole multilayer coil structures are made of pure copper and have no delamination defects. The closed magnetic core is built of electrochemically deposited soft magnetic alloy CoFe 45/55 . In order to reduce the residual low electrical conductivity of the polyimide surface which will be brought by ion beam etching substrate cooled sputter etching is used. Another step of preparing the copper surface after wet chemical development of photosensitive polyimide is presented. The surface cleaning is necessary for successful ultrasonic wire bonding. The final embedding of the device into a QFN-package is needed for the characterization. It is fulfilled with two component epoxy which has a wide temperature working range. The functionality of fabricated micro magnetic device was tested in high frequency DC-DC step down converter. For this test a specific integrated circuit MDCD073 a dual 7V PN half bridge with pre-drivers in 180 nm SOI technology is used. The frequency of the convertor was from 15 MHz to 30 MHz. The micro device shows the efficiency of about 80 % for output currents between 300 mA to 800 mA. The electrical resistance of the devices, with all four coils in serial connection, is 250 mΩ. The measured inductivity is above 50 nH which is stable up to very high frequencies. Yet the breakthrough voltage has to be determined as well as the impedance parameter which will be calculated from the s-parameters by matrix transformation. [1] Xing, Xing; Sun, Nian X;Chen, Baoxing; High-Bandwidth Low-Insertion Loss Solenoid Transformers Using FeCoB Multilayers; IEE Transactions on Power Electronics 2012 Vol 28 4395-4401 [2] Feeney, Ciaran; Wang, Nigning; Mathúna, Seán Cian; Duffy, Maeve; A 20-MHz 1.8-W DC–DC Converter With Parallel Microinductors and Improved Light-Load Efficiency; IEEE Transactions on Power Electronics 2015 Vol 30 771-779 [3] Dinulovic, Dragan; Gerfer, Alexander; Opitz, Oliver; Kaiser, Matthias; Wurz, Marc C., Rissing, Lutz; Thin-Film Microtransformer for High Frequency Power Application; Joint European Magnetic Symposia 2014 Vol 75 [4] Dinulovic, Dragan; Kaiser, Matthias; Gerfer, Optiz, Oliver, Martin; Wurz, Marc C., Rissing, Lutz; Microtransformer with closed Fe-Co magnetic core for high frequency power applications; Journal of Applied Physics 2014 Vol 115 17A317-1 – 17A317-3 [5] Dinulovic, Dragan; Gerfer, Alexander; Haug, Martin; Kaiser, Matthias; Wurz, Marc C., Rissing, Lutz; Improved Microtransformer Design Utilizing Fe-Co Magnetic Core; Physics Procedia 2015 Vol 75 1252-1258 [6] Dinulovic, Dragan; Shousha, Mahmoud; Haug, Martin; Beringer, Sebastian; Wurz, Marc C.; Thin-Film Based Microtransformer Suitbale for High Switching Frequency Power Applications, in press Figure 1

Orientational entropy and dipolar aggregation in mixtures of propylene carbonate + N,N-dimethylacetamide

The analysis of temperature behavior of the orientational entropy increment induced by the probing electric field, has been performed for two strongly polar liquids: propylene carbonate (PC) and dimethylacetamide (DMA), in the neat states as well as mixed together. It has been found that in the both neat fluids, the molecular dipoles self-assemble in a parallel, the head-to-tail way, wherein the effect is significantly higher in a less polar dimethylacetamide. This proves a better structural adjustment of DMA molecules to their effective self-association. In the mixtures of these two self-assembled liquids, the mixed dipolar aggregates consisting of molecules PC and DMA occur, in contrast to the mixtures of PC+DMSO (dimethyl sulfoxide), where the highly polar molecules of DMSO, being not capable for self-association, play only a neutral role of the filler the space between assemblies composed of PC molecules. The residual electrical conductivity in mixtures under investigation has been characterized.

16-17: Contact-force guided single catheter approach for pulmonary vein antrum isolation: procedural feasibility

Purpose: Wedging a circular mapping catheter (CMC) into pulmonary vein (PV) is recommended to validate their isolation during wide antral circumferential ablation (WACA). Since appropriate catheter contact has proved crucial for lesion quality, we hypothesize that a contact-force (CF) guided single catheter approach might be suitable and effective for PV isolation (PVI). Methods: With the use of a CF ablation catheter, WACA was performed for both sets of PVs in 50 patients with paroxysmal AF. Antral exit block was demonstrated by sequential pacing at 9 equidistant points within the circular WACA lesion set (including the carina), with a target force ≥ 10g. Sites displaying persistent left atrial capture underwent additional pacing maneuvers and electrogram analysis, in order to detect and close residual gaps. Once exit block was deemed achieved, PVI was validated by conventional CMC-based analysis. Results: The mean procedural duration, fluoroscopy exposure time, total ablation time and force applied per-procedure were respectively of 101 ± 17 min, 5.6 ± 2.2 min, 23.2 ± 7.1 min and 17.8 ± 2.6 grams. 84 of 100 PV antra were disconnected after an exclusive anatomical approach, while 16 displayed residual gaps. Of the latter, 14 were isolated with the sole CF catheter. The positive predictive value of antral exit block reached 100% for predicting PVI as assessed with CMC. Conclusions: CF-guided single catheter technique is a feasible method for PVI in patients with paroxysmal AF. This simplified approach proves as effective as the standard CMC-based approach for residual gaps identification and conduction block validation.

Resonant impurity states in chemically disordered half-Heusler Dirac semimetals

We address the electron transport characteristics in bulk half-Heusler alloys with their compositions tuned to the borderline between topologically nontrivial semi-metallic and trivial semiconducting phases. The precise first-principles calculations based on the coherent potential approximation (CPA) reveal that all the studied systems exhibit sets of dispersionless impurity-like resonant levels, with one of them being located right at the Dirac point. By means of the Kubo formalism we reveal that the residual conductivity of these alloys is strongly suppressed by impurity scattering, whereas the spin Hall conductivity exhibits a large value which is comparable to that of Pt, thereby leading to divergent spin Hall angles.

Topological Kondo Insulators

This article reviews recent theoretical and experimental work on a new class of topological material—topological Kondo insulators, which develop through the interplay of strong correlations and spin-orbit interactions. The history of Kondo insulators is reviewed along with the theoretical models used to describe these heavy fermion compounds. The Fu-Kane method of topological classification of insulators is used to show that hybridization between the conduction electrons and localized f electrons in these systems gives rise to interaction-induced topological insulating behavior. Finally, some recent experimental results are discussed, which appear to confirm the theoretical prediction of the topological insulating behavior in samarium hexaboride, where the long-standing puzzle of the residual low-temperature conductivity has been shown to originate from robust surface states.

Stochastic Model of Gap Junctions Exhibiting Rectification and Multiple Closed States of Slow Gates

Gap-junction (GJ) channels formed from connexin (Cx) proteins provide direct pathways for electrical and metabolic cell-cell communication. Earlier, we developed a stochastic 16-state model (S16SM) of voltage gating of the GJ channel containing two pairs of fast and slow gates, each operating between open (o) and closed (c) states. However, experimental data suggest that gates may in fact contain two or more closed states. We developed a model in which the slow gate operates according to a linear reaction scheme, o↔c1↔c2, where c1 and c2 are initial-closed and deep-closed states that both close the channel fully, whereas the fast gate operates between the open state and the closed state and exhibits a residual conductance. Thus, we developed a stochastic 36-state model (S36SM) of GJ channel gating that is sensitive to transjunctional voltage (Vj). To accelerate simulation and eliminate noise in simulated junctional conductance (gj) records, we transformed an S36SM into a Markov chain 36-state model (MC36SM) of GJ channel gating. This model provides an explanation for well-established experimental data, such as delayed gj recovery after Vj gating, hysteresis of gj-Vj dependence, and the low ratio of functional channels to the total number of GJ channels clustered in junctional plaques, and it has the potential to describe chemically mediated gating, which cannot be reflected using an S16SM. The MC36SM, when combined with global optimization algorithms, can be used for automated estimation of gating parameters including probabilities of c1↔c2 transitions from experimental gj-time and gj-Vj dependencies.

Performance of Separation Processes for Precipitated Calcium Carbonate Produced with an Innovative Method from Steelmaking Slag and Carbon Dioxide

In this work, experiments were performed to determine the filterability of calcium carbonate produced with an alternative calcium carbonate production concept. The concept uses steelmaking slag as raw material and has potential to fix CO2 emissions and utilize steelmaking slag, simultaneously. As calcium carbonate is precipitated in a solution containing ammonium chloride, calcium chloride and ammonia, the product needs to be washed and hence filtered. In this work different separation processes, including washing, filtering and drying, were tested on two calcium carbonate slurries produced from steel converter slag and CO2 by a laboratory-scale pilot facility, with the aim of obtaining a solid product with a low chloride content using a minimum amount of washing water. The order of maximum filtration rates achievable of the calcium carbonate slurries was determined by experimental work. The tests included pressure filtration and vacuum filtration and the test series contained altogether 21 different filtration cycles with varying combinations of filtering, washing, and drying steps. The filtered cakes were analyzed by their residual moisture content, chloride content and conductivity, and the filtrates by their residual solids content, chloride content and conductivity. Pressure filtration gave a high capacity (400-460 kg/m2h) and a low cake residual moisture content (12-14 wt-%). Vacuum filtration gave slightly higher filtration rates (500-610 kg/m2h at the lowest residual chloride contents of the cakes), but the cake residual moisture also stayed higher (25-26 wt-%). As the vacuum filtration tests used a filter cloth with higher permeability than that of the pressure filtration tests, a slightly higher filtration rate was expected. However, both filtration technologies seem suitable for filtering and washing calcium carbonate prepared with the studied method as a residual chloride content as low as 10 ppm of the filtered solids can be achieved with quite a small amount of washing water and the filtration rate is fast.

Thermal Conductivity Measurements of Caged Structural Superconductors

Thermal conductivity of Ca3Rh4Sn13 and Sr3Ir4Sn13 were measured in magnetic fields to reveal superconducting state. From magnetic susceptibility χ(T) and electrical resistivity ρ(T) measurements, superconducting transition temperature Tc of Ca3Rh4Sn13 and Sr3Ir4Sn13 is determined to be 8 and 5K, respectively. Thermal conductivity κ(T) of Ca3Rh4Sn13 indicates that superconducting state is nodeless s-wave, because residual thermal conductivity κ0/T in zero magnetic field is very small. On the other hand, κ(T) of Sr3Ir4Sn13 in zero magnetic field suggests that superconductivity possesses nodal gap rather than full gap. Whether nodal superconducting gap exists or not still remains to be clarified, because there is a possibility that the achieving temperature is insufficient to discuss superconducting state.

Numerical simulations of residual stress and inhomogeneous conductivity effects in CNT-filled resins cured by electric field

Numerical simulations of residual stress and inhomogeneous conductivity effects in CNT-filled resins cured by electric field

Mechanisms of postoperative atrial tachycardia following biatrial surgical ablation of atrial fibrillation in relation to the surgical lesion sets

Atrial tachycardia (AT) may develop after biatrial surgical ablation of atrial fibrillation. However, the mechanism has not been determined in detail. We aimed to determine the mechanism and treatment of postoperative AT following biatrial surgical ablation in relation to the design and durability of the surgical lesion sets. An electrophysiologic study and radiofrequency ablation were performed in 34 consecutive patients (23 male, mean age of 63 ± 9.4 years) who were referred for AT that developed late after biatrial surgical ablation. The mechanism of a total of 53 ATs was macroreentry in 30, a focal mechanism in 20, and localized reentry in 1, and could not be determined in 2. The cause of the macroreentrant AT was residual conduction across a surgical lesion, most of which was located at the annular end of the mitral (n = 18) or tricuspid isthmus incision (n = 7), where cryoablation was applied during the surgery. We did not find any gaps across the cut-and-sew lesions. Radiofrequency (RF) applications to the gap, or an alternative site to transect the circuit, or the earliest activation site of the focus was effective for 48 ATs (91%). After a total of 1.3 ± 0.6 RF sessions, 27 patients (79%) were free of AT (n = 2) or AF (n = 5) during a follow-up period of 50 ± 49 months. Macroreentry due to a gap in a surgical lesion and focal AT were the major mechanisms of AT in patients after biatrial surgical ablation. Radiofrequency ablation of those ATs is feasible.