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Global warming has altered the uniformity of precipitation in Inner Mongolia, China, eventually leading to droughts. Further studies are necessary to determine the relationship between the concentration of precipitation and drought. Therefore, we assessed the spatial and temporal characteristics of the precipitation concentration degree (PCD), precipitation concentration period (PCP), and standardized precipitation evapotranspiration index (SPEI) in Inner Mongolia in the past (1961–2017) and predict changes in the three indices under different scenarios in the future (2018–2100) using measured model data and Sen's slope and Mann–Kendall trend analysis. The correlation between PCD/PCP and SPEI was explored using Pearson's correlation coefficient. The results showed that the spatial distribution of PCD and PCP in Inner Mongolia exhibited significant east–west differences. The PCD values were 0.42–0.76, with high‐value areas in the east. PCD showed a decreasing trend in both historical and future scenarios, indicating an even distribution of precipitation and an increased risk of drought. The PCP values were 190°–226°, with high‐value areas mainly in the western region. Except for in the Representative Concentration Pathways RCP4.5 and RCP8.5, PCP values in the historical and RCP2.6 scenarios showed a decreasing trend, indicating an earlier onset of maximum precipitation. SPEI values ranged between −1.23 and 1.17, with all future scenarios showing a decreasing trend and the historical scenario showing an increasing trend. The stations with positive correlation between SPEI and PCD accounted for 89.13, 67.39, 91.3, and 95.65% of Inner Mongolia, while those with positive correlation with PCP accounted for 43.47, 60.87, 56.52, and 4.35%, indicating that the correlation between drought variation and precipitation concentration is strong. These results can help reduce and prevent droughts and floods caused by changes in precipitation patterns and provide a basis for the rational use of water resources for preventing droughts and making relief decisions. [ABSTRACT FROM AUTHOR]

Background: Ablation index (AI) is a novel technology of ablation lesion quality to help improve homogeneity of lesion size and continuity. In this study, we aim to evaluate whether AI‐guided PVI improves clinical outcomes compared to CF‐guided PVI in patients with paroxysmal AF (PAF). Methods: Patients undergoing first‐time radiofrequency ablation for PAF were randomized in a 2:1 ratio to two groups: AI‐guided PVI and CF‐guided PVI. In the AI group, AI ≥500 was recommended at the anterior/superior/inferior walls, 350–400 at the posterior wall, and inter‐lesion distance ≤4 mm. The primary endpoint is the freedom from atrial arrhythmia recurrence during 12 months follow‐up, without antiarrhythmic drug therapy (ADT). The key secondary endpoints include intra‐procedural efficiency and peri‐procedural complications. Results: Two hundred twenty five patients were randomized (AI group [n = 149] and CF group [n = 76]). First‐pass isolation rate in AI group was significantly higher than that in CF group (58.3% vs. 43.4%, p =.035). After a median follow‐up of 12.2 months, 154/225 (68.4%) of patients were free from atrial arrhythmia recurrence without ADT, which was higher in AI group compared with CF group, but without significant difference (71.1% vs. 63.2%, p =.253). The incidence of peri‐procedural complications is low and without difference between two groups. Conclusions: AI‐guided ablation provided higher acute efficacy than CF‐guided ablation in PV isolation for patients with paroxysmal AF. The long‐term success rate in AI group was higher than CF group, but did not reach statistical significance. [ABSTRACT FROM AUTHOR]

Using solvent additives to optimize the morphology of the blend films in organic solar cells (OSCs) is a simple and effective method. Here, methyl salicylate (MeSA) is used as a non‐halogen additive for inverted OSCs, and the impact of this additive on the blend film and photovoltaic performance is carefully investigated. The significant increase in short‐circuit current density (JSC) and fill factor (FF) leads to a significant improvement in device performance, which is caused by bicontinuous interpenetrating phase separation and balanced charge transport. The results indicate that MeSA modulates the phase distribution and promotes the accumulation of ordered molecules in the blend film, thus exhibiting an efficiency of 9.45% and improved FF (>70%) with a 7% MeSA additive. Most importantly, MeSA can be added in large doses (7%) compared to other traditional solvent additives (e.g., 1,8‐diiodooctane, 1‐chloronaphthalene, etc.), indicating that its concentration variation has little effect on performance and is conducive to repeatable, large‐scale production, which is of great importance for industrialization. [ABSTRACT FROM AUTHOR]

For organic photovoltaic cells, the development of new green solvents and nontoxic and halogen‐free additives is an urgent issue. Here, a simple combination of o‐xylene (O‐XY) and ethyl 2‐hydroxybenzoate (EHB) is introduced in inverted devices based on poly[4,8‐bis(5‐(2‐ethylhexyl)‐thiophene‐2‐yl) benzo[1,2‐b;4,5‐b′] dithiophene‐2,6‐diyl‐alt‐(4‐(2‐ethylhexyl)‐3‐fluorothieno[3,4‐b] thiophene)‐2‐carboxylate‐2‐6‐diyl]:[6,6]‐phenyl‐C71‐butyric acid methyl ester (PTB7‐Th:PC71BM) as blend layers, the device performance reaches optimal values (9.29%) when O‐XY and 3% EHB are introduced as additives, accompanied by the maximum fill factor (67.5%) and JSC (17.20 mA cm−2). From the results of characterization analysis, it is clear that EHB additive improves the crystallinity of the donor by regulating the kinetic process of active layer formation, selectively solubilizes the more aggregated fullerene acceptors, which allows PTB7‐Th to enter the conformational domain of PC71BM, and accelerates the molecular rearrangement. Besides, the EHB additive not only reduces the recombination, increases the carrier migration rate but also promotes the crystallinity of the donor, resulting in a tighter stacking. This work provides a green combination of solvents and additives that is important for the mass production of solar cells. [ABSTRACT FROM AUTHOR]

Organic solar cells (OSCs) are considered as a promising new generation of clean energy. Bulk heterojunction (BHJ) structure has been widely employed in the active layer of efficient OSCs. However, precise regulation of morphology in BHJ is still challenging due to the competitive coupling between crystallization and phase separation. Recently, a novel pseudo‐planar heterojunction (PPHJ) structure, prepared through solution sequential deposition, has attracted much attention. It is an easy‐to‐prepare structure in which the phase separation structures, interfaces, and molecular packing can be separately controlled. Employing PPHJ structure, the properties of OSCs, such as power conversion efficiency, stability, transparency, flexibility, and so on, are usually better than its BHJ counterpart. Hence, a comprehensive understanding of the film‐forming process, morphology control, and device performance of PPHJ structure should be considered. In terms of the representative works about PPHJ, this review first introduces the fabrication process of active layers based on PPHJ structure. Second, the widely applied morphology control methods in PPHJ structure are summarized. Then, the influences of PPHJ structure on device performance and other property are reviewed, which largely expand its application. Finally, a brief prospect and development tendency of PPHJ devices are discussed with the consideration of their challenges. [ABSTRACT FROM AUTHOR]

Abstract: Background: Radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF) is known to induce left atrial remodeling and prothrombotic response. Aims: This study aimed to evaluate the effect of remote ischemic preconditioning (RIPC) on left atrial remodeling and prothrombotic response induced by RFCA of AF. Methods: Forty‐four patients with drug‐refractory paroxysmal AF undergoing RFCA were randomized into RIPC (four short episodes of forearm ischemia) and control groups before the procedure. Blood samples were collected before RIPC/sham RIPC, and 24 and 72 hours later after the procedure. The atrial remodeling marker matrix metalloproteinase‐9 (MMP‐9) and endothelial damage marker von Willebrand factor (vWF) were measured using enzyme‐linked immunosorbent assay. Platelet activation was evaluated by flow cytometric measurements of the expression of platelet P‐selectin (CD62P) and active glycoprotein IIb/IIIa receptor (PAC‐1). The early recurrence of atrial fibrillation (ERAF) in the two groups was observed over the subsequent 3 months. Results: RFCA resulted in a significant increase in MMP‐9 and vWF in both the groups, which persisted for 72 hours. However, the expression of CD62P and PAC‐1 showed less increase during RFCA in either group. The RIPC group showed a lower increase in MMP‐9 and vWF compared with the control group. In contrast, no significant differences were found in the trend of expression of CD62P and PAC‐1 during RFCA between the two groups. The AF recurrence in the 3 months after the ablation was significantly lower in the RIPC group than in the control group. Conclusions: RIPC before RFCA for paroxysmal AF significantly reduces the increase in markers of left atrial remodeling and endothelial damage associated with the procedure, and results in a lower ERAF. [ABSTRACT FROM AUTHOR]

An Au/Ni/Hf0.5Zr0.5O2/Au flexible memory device fabricated on a polyethylene terephthalate substrate was studied for flexible resistive random access memory applications. A typical bipolar resistive switching behavior was revealed with an OFF/ON ratio of approximately 15. The reproducibility and uniformity were investigated using 100 repetitive write/erase cycles. The retention property did not degrade for up to 5 × 104 s, and the resistive switching properties did not degrade even under bending conditions, which indicated good mechanical flexibility. The current–voltage characteristics of the memory device show a Poole–Frenkel emission conduction mechanism in the high‐voltage region in the high‐resistance state, while in the low‐voltage region, the Ohmic contact and space charge limit current responded to the low‐resistance state and high‐resistance state, respectively. Combined with the conductance mechanism, the resistive switching behavior is attributed to conductive filaments forming and rupturing due to oxygen vacancies migrating under the external driving electric field. [ABSTRACT FROM AUTHOR]

Impact of PFO on LA Linear Ablation. Introduction: We investigated the impact of the mode of left atrial (LA) access via patent foramen ovale (PFO) versus transseptal (TS) puncture on LA linear lesions during atrial fibrillation (AF) ablation. Methods and Results: We investigated 139 (PFO: 25) consecutive patients who underwent mitral isthmus (MI) and/or LA roof linear ablation. Technical endpoint was completeness of linear lesions and duration of radiofrequency (RF) application. During the initial procedure, complete MI and LA roof blocks were created in 13 of 19 (68%) and 14 of 17 (82%) patients in the PFO group, and in 57 of 94 (61%) and 54 of 70 (74%) patients in the TS group, respectively (P = NS). There was no significant difference in RF durations at MI (11.1 ± 8.9 and 15.1 ± 7.6 minutes, P = 0.11), and LA roof (10.1 ± 3.5 and 8.3 ± 5.0 minutes, P = 0.21) between the 2 groups. Among 28 patients who underwent repeat linear ablation, complete MI and LA roof blocks were created in 3 of 4 (75%) and 0 of 1 (0%) patients in the PFO group, and in 16 of 21 (76%) and 7 of 10 (70%) patients in the TS group, respectively (P = NS). There was no significant difference in RF durations at MI (15.3 ± 8.3 and 19.5 ± 18.3 minutes, P = 0.71), and LA roof (19.0 and 10.3 ± 5.4 minutes, P = 0.19) between the 2 groups. Clinical outcomes at 12 months were also similar. Conclusion: There were no significant differences in the procedural success rates, durations of RF application, 12-month clinical outcomes, and complication rates of LA linear ablation between the PFO and TS groups. Accessing the LA via a PFO is not an unfavorable approach toward LA linear ablation. (J Cardiovasc Electrophysiol, Vol. 22, pp. 846-850, August 2011) [ABSTRACT FROM AUTHOR]

LA Linear Ablation With Multielectrode Catheter. Introduction: Creating complete linear block with point-by-point ablation is challenging in the left atrium (LA). The purpose of this study was to evaluate the efficacy of LA linear ablation using a hexapolar linear multielectrode mapping/ablation catheter. Methods and Results: Seventeen patients (age 57 ± 10, 14 male, 6 paroxysmal AF (PAF)) were studied and underwent linear ablation at the mitral isthmus (MI) and LA roof. Ablation was performed with 90 second, 60 °C applications of duty-cycled bipolar/unipolar radiofrequency in a 1:1 ratio simultaneously at all selected electrode pairs. The result could not be evaluated in 2 patients because AF persisted despite cardioversion. Roof line block was confirmed in 9 of 15 (60%) patients. The mean number of applications and the procedural time with and without block was 5.4 ± 2.4 and 4.5 ± 2.2 applications, and 15 ± 8 and 13 ± 7 minutes. MI block was confirmed in 4 of 15 (27%) patients. The mean number of RF applications with and without block was 5.3 ± 2.2 and 9.9 ± 4.4 applications, and the procedural time was 20 ± 9 and 27 ± 10 minutes, respectively. For patients with underlying persistent AF, power was lower than those with PAF but improved when ablation was performed in sinus rhythm. Char was observed in 2 cases; however, no procedure-related complications were observed. Conclusions: In our initial experience, a linear multielectrode catheter using duty-cycled bipolar and unipolar RF energy was inferior to conventional single point irrigated ablation in achieving LA linear block. However, successful linear block was obtained within a short period of time, when it was achieved. (J Cardiovasc Electrophysiol, Vol. 22, pp. 739-745, July 2011) [ABSTRACT FROM AUTHOR]

The article presents a case study of a 71-year-old man with an eccentric coronary sinus (CS) activation pattern in perimitral flutter. It states perimitral flutter is the most common macroreentrant left atrial tachycardia that can arise from atrial fibrillation ablation. It mentions tiny far-field potentials originating from the left atrium could be observed in CD electrograms taken during tachycardia. It comments activation patterns of CS bipoles did not reflect tachycardia circuit activity.

Ligament of Marshall and Atrial Fibrillation Induction. Background: The role of ligament of Marshall (LOM) in the mechanism of “vagal” atrial fibrillation (AF) is still unknown. Objective: To investigate the impact of LOM ablation on atrial vulnerability to AF induced by inferior left atrial fat pad (ILAFP) stimulation in dogs. Methods: AF inducibility and atrial effective refractory period (ERP) were elevated before and after LOM ablation in 8 of 14 dogs (the ablation group). Same protocol but without LOM ablation was conducted in the remaining 6 dogs (the control group). The activation patterns of LOM and left pulmonary veins (LPVs) during sustained AF were analyzed. The distribution of epicardial cholinergic nerve fibers between LOM and ILAFP was investigated in the control group. Results: Ablation of LOM significantly attenuated AF inducibility (87.5% vs 33.3%, P < 0.001) and prolonged ERPs of the structures in contiguity with LOM (P < 0.05) in the ablation group. In contrast, there was no significant change in ERPs and AF inducibility in the control group. During sustained AF, fractionated atrial electrograms were more common in the LOM area than the LPVs (84% vs 18% of the analyzed episodes, P < 0.001). In 46.7% of the episodes with identifiable LOM spikes, atrial potentials, and LOM spikes were related in 2:1 or 3:2 pattern during the intermittent organized activity. Acetylcholinesterase staining revealed a close cholinergic nerved relationship between LOM and ILAFP. Conclusions: LOM plays a critical role in maintaining AF induced by stimulation of ILAFP. Ablation of LOM can markedly attenuate AF inducibility in this model. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1024-1030, September 2010) [ABSTRACT FROM AUTHOR]

A New Method to Evaluate Linear Block at the Left Atrial Roof. Objective: The present study aimed to evaluate a new method for validation of complete linear block at the left atrial (LA) roof. Background: Linear lesions at the LA roof have been reported to improve the success rate of catheter ablation of atrial fibrillation (AF). Methods: Complete linear block at the LA roof was evaluated in 31 patients after complete isolation of pulmonary vein antrum (PVA) using a simple method. We hypothesized that complete linear block of the LA roof could be confirmed during sinus rhythm if (1) a continuous line of double potentials could be recorded at the LA roof, and (2) the activation sequence along the posterior wall changed to caudocranial. The results of this method were compared with standard pacing techniques. Results: Thirty-nine lines were assessed using this method: 8 before and 31 after achievement of complete conduction block. After validation of complete linear block at the LA roof, double potentials with a mean interpotential interval of 60 ± 13 ms were recorded in 25 patients and electroanatomical mapping of the left atrium showed the activation sequence of posterior wall changed to caudocranial in all 31 patients during sinus rhythm. The sensitivity, specificity, positive and negative predictive values of this method for validating complete linear block were 100%, 88.9%, 96.8%, and 100%, respectively. Conclusion: A corridor of double potentials along the roof line and a caudocranial activation sequence along the posterior wall during sinus rhythm can indicate conduction block at the LA roof after PVA isolation. (J Cardiovasc Electrophysiol, Vol. pp. 741-746, July 2010) [ABSTRACT FROM AUTHOR]

Background: Video-assisted thoracoscopic bilateral pulmonary vein (PV) isolation with left atrial appendage (LAA) excision is a novel surgical treatment for patients who have atrial fibrillation (AF) but no indication for open heart surgery. However, the electrophysiological mechanisms of the recurrent atrial tachyarrhythmias after this procedure are unknown. Methods: Eight consecutive patients with highly symptomatic atrial tachyarrhythmias after failed video-assisted thoracoscopic surgery were included in this study. A predetermined stepwise ablation protocol, aimed at termination of the arrhythmia and isolation of all PVs, was conducted. The conduction across the remnant of the LAA was also evaluated in 4 patients. Results: Three patients had AF, which was converted into AT by complex fractionated atrial electrogram ablation in 2. Eleven sustained ATs in 7 patients were mapped during the procedure. A majority of ATs (10 of 11) were terminated by ablation before PV isolation. In total, 10 PV gaps in 7 patients were identified. All residual PV gaps were distributed exclusively in the roof or the bottom of the PV antrum. The conduction time across the remnant of the LAA was 90.7 ± 11.5 ms. One patient underwent a repeat successful ablation procedure. After a mean follow-up of 10.1 ± 5.0 months after the last ablation procedure, 7 of 8 patients were free of clinical atrial tachyarrhythmias recurrence. Conclusion: PV gaps are present, with a characteristic distribution, in the majority of patients who fail this surgical procedure, but these gaps are not responsible for the arrhythmias identified. Instead, most are macro-reentrant, isthmus-dependent arrhythmias related to clamp-associated or LAA excision-associated scars. [ABSTRACT FROM AUTHOR]

Objectives: The present study was designed to investigate the feasibility and efficacy of single ablation catheter for complete circumferential pulmonary vein antrum (PVA) isolation. Background: Complete isolation of pulmonary veins is the mainstay for atrial fibrillation (AF) ablation. This is usually performed under the guidance of a circular catheter. Methods: One hundred and ten consecutive patients with paroxysmal AF were prospectively randomized into two groups: single-catheter approach (group 1) and double-catheter approach (group 2). After performing initial circumferential lesions, residual gaps were mapped and closed with single ablation catheter in group 1 or guided by a circular mapping catheter in group 2 using an electroanatomic mapping system (CARTO™ XP, Biosense-Webster Inc., Diamond Bar, CA, USA). Results: Complete bilateral PVA isolation was achieved in 22 of the 110 patients after initial ablation. All residual gaps could be correctly identified by activation mapping using single ablation catheter. The distribution of these residual gaps was asymmetric. In group 1, 25 gaps along the right PVA lesions and 49 gaps along the left PVA lesions were identified. All the residual gaps were closed with single-catheter approach. In group 2, 28 gaps on the right side and 53 gaps on the left side were identified using a circular catheter and closed with further ablations. The procedure data and clinical outcomes between the two groups were comparable. Conclusions: Single ablation catheter technique is feasible and as effective as circular catheter mapping in localizing the residual gaps for PVA isolation during ablation of paroxysmal AF. [ABSTRACT FROM AUTHOR]

Background: Common ostium of the inferior pulmonary veins (PVs) is a kind of unusual variation in pulmonary venous drainage to the left atrium (LA), whose feature of anatomy, electrophysiology, and catheter ablation is rarely demonstrated, and the consecutive series of research for catheter ablation of atrial fibrillation (AF) in patients with that anomaly have not been reported. Methods: A total of 1,226 patients with drug-refractory AF received magnetic resonance angiography (MRA) or multidetector computed tomography (MDCT) scan before ablation. Electrophysiological mapping was used to detect the focal triggers in paroxysmal AF. Basic catheter ablation strategy was circumferential PV isolation with “tricircle” under the guidance of image integration system: two circles surround two superior PVs, and the other surround the common trunk. Results: LA and PVs reconstruction by image integration system showed a common pulmonary venous ostium of the right and left inferior PVs before ablation in 11 patients (0.9%). This anomaly could be classified into two types: type A without a short common trunk of inferior PVs and type B with a short common trunk. Fifty-seven percent paroxysmal AF was revealed focal triggers in the common ostium. The success rate of that strategy was 90%. Conclusion: Common ostium of inferior PVs could be classified into two types according to the presence of a short common trunk or not. The common ostium was usually an important triggering focus in paroxysmal AF. Catheter ablation strategy of circumferential PV isolation with “tricircle” under the guidance of image integration system would be a good choice. [ABSTRACT FROM AUTHOR]

Introduction: Circumferential pulmonary vein ablation (CPVA) with the endpoint of pulmonary vein (PV) isolation has been developed as an effective therapy for atrial fibrillation (AF). This endpoint can be achieved either by closing gaps along circular lines or by segmental PV isolation inside the circular lines after creation of initial CPVA lesions. We investigated whether the clinical outcome depends on the PV isolation approach used during the first-time CPVA procedure. Methods and Results: One hundred consecutive patients (69 male; age, 56.7 ± 11.6 years) who underwent first-time CPVA for treatment of symptomatic AF were enrolled. PV isolation was randomly achieved either by CPVA alone (aggressive CPVA [A-CPVA] group, n = 50) or by a combination of CPVA with segmental PV ostia ablation (modified CPVA [M-CPVA] group, n = 50). Recurrence of atrial tachyarrhythmias (ATa) within 3 months after the initial procedure occurred in 30 patients (60%) in the M-CPVA group and in only 15 patients (30%) in the A-CPVA group (P < 0.01). ATa relapse after the first 3 months was detected in 21 patients (42%) in the M-CPVA group, compared with 9 patients (18%) in the A-CPVA group (P = 0.01). At 13 ± 4 months, patients treated by the A-CPVA approach had greater freedom from ATa recurrence than patients who underwent M-CPVA (P = 0.01). The M-CPVA approach was the only independent predictor associated with procedural failure (RR 0.318; 95% CI 0.123–0.821; P = 0.02). Conclusions: When PV isolation is the endpoint of CPVA, the efficacy of the A-CPVA approach is better than that of M-CPVA. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 55-year-old man with symptomatic, persistent atrial fibrillation (AF) who underwent pulmonary vein isolation and linear ablation of mitral isthmus (MI) and left atrial roof. The man was referred for the ablation of incessant left atrial tachycardia (AT) three months later. Topics include an overview of perimitral atrial tachycardia AT and the results from an entrainment mapping of perimitral flutter in the man's left atrium.

The article presents images which show the left superior pulmonary vein (LSPV) antral ablation provoking sinus bradycardia which led to atrioventricular block in a 36-year-old man with paroxysmal atrial fibrillation who underwent circumferential pulmonary vein isolation with a decapolar circular ablation catheter.