Node Modification Research Articles

Dual-Metal-Site Metal-Organic Frameworks for Oxygen Reduction: The Crucial Role of Environmental Species Covering on the Secondary Site.

Macrocycle-based dual-metal-site metal-organic frameworks emerge as promising catalysts whose activity can be conveniently manipulated via metal node modification. However, how the metal node affects catalysis remains unclear. Herein, using first-principles calculations, we provide new mechanistic insight into dual-metal-site catalysis, where the recently synthesized M1-CoOAPc materials (M1 = Co, Ni, Cu; OAPc = octaaminophthalocyanine) are adopted for demonstration. The modeling results explain experimental measurements of Ni- and Cu-CoOAPc for facilitating oxygen reduction while highlighting a contradiction between the theoretical and experimental activity of Co-CoOAPc. Remarkably, this contradiction is attributed to the inherent H2O adsorption on Co nodes, which is usually neglected in dual-metal-site studies. We expand M1-CoOAPc with other metal nodes and find that Fe-CoOAPc (involving *H2O on the Fe nodes) exhibits a desirable theoretical half-wave potential of 0.82 V, as revealed from constant-potential and microkinetic modeling. This work improves the understanding of dual-metal-site catalysis by uncovering the impact of environmental species covering on the secondary site.

Successful Three-Dimensional Mapping-Guided Sinus Node Modification for Drug-Refractory Inappropriate Sinus Tachycardia after Circumferential Pulmonary Vein Isolation.

Successful Three-Dimensional Mapping-Guided Sinus Node Modification for Drug-Refractory Inappropriate Sinus Tachycardia after Circumferential Pulmonary Vein Isolation.

Cardioneuroablation for reflex asystolic syncope: Mid-term safety, efficacy, and patient’s acceptance

BackgroundCardioneuroablation (CNA) is a promising therapy for reflex asystolic syncope; however, convincing data on the mid-term safety and efficacy of this procedure are lacking. ObjectiveThe purpose of this study was to assess the mid-term safety, efficacy, and patient acceptance of CNA. MethodsThis prospective observational single-center study included 115 consecutive patients (mean age 39 ± 13 years; 58% female) treated between 2016 and 2022 who completed at least 1-year follow-up. ResultsNo significant procedure-related acute complications occurred. During median follow-up of 28 months (range 12–75), 95 (83%) remained free from syncope. Of the 20 patients (17%) with syncope recurrence, syncope burden decreased from a mean 17 (median 6.5) to 3.75 (median 2.5) episodes (P = .015). In 9 of 10 patients, pacing system removal was possible. Repeated CNA was needed in 3 patients (3%), whereas pacemaker implantation was performed in 5 (4%). The most frequent mid-term complication of CNA was sinus rhythm acceleration (from 60 ± 14 bpm to 90 ± 16 bpm; P <.0001), which was symptomatic in 31 patients (27%); 8 patients (7%) required chronic beta-blocker and/or ivabradine. Sinus node modification was necessary in 1 patient. Other complaints included dyspnea, chronic chest pain, and decreased exercise capacity, which were mild and reported by 16 patients (14%). Patient acceptance of CNA was very high: 96% stated that it was worth undergoing the procedure. ConclusionsMid-term efficacy of CNA exceeds 80%, and acute complications are absent. The most frequent mid-term chronic complication is inappropriate sinus tachycardia, which in 7% required chronic treatment. The procedure is well accepted by patients.

Abstract 14607: Management of Inappropriate Sinus Tachycardia: A Promising Breakthrough

Introduction: Inappropriate Sinus Tachycardia (IST) is a cardiac dysautonomia with limited treatment options. This case highlights the effectiveness of a novel sinus node-sparing hybrid surgical ablation (SNSHA) for IST. Objective: To describe a novel hybrid surgical approach for management of IST. Case Description: A 43 y/o female presented with history of palpitations/tachycardia for 5 years. A comprehensive evaluation directed towards the diagnosis of IST with resting heart rates (HR) above 100 bpm and HR changes greater than 30% with minimal exertion. A trial of ivabradine &amp; beta blockers along with lifestyle modifications offered limited relief. Patient was offered the novel SNSHA after a shared decision-making process. Methods: The SNSHA is a minimally invasive procedure performed by a CT surgeon in conjunction with an electrophysiologist involving thoracoscopic epicardial ablation of the sympathetic connections from the SVC to the IVC. The thoracoscopic approach allows for safeguarding of the phrenic nerve and sinus node followed by endocardial ablation along the lateral wall. Results: Intraprocedural pre and post ablation electroanatomic map (EAM) and electrogram (EGM) demonstrated an immediate drop in HR as shown in the Figure 1(a-d). An ILR was implanted during the procedure. On 45-day post-op visit, the patient experienced significant symptom relief and improvement in her HR as well as HR variability on ILR as shown in Figure 1(e). Conclusion: SNSHA offers a reasonable treatment option for patients with drug resistant IST. This procedure provided symptom alleviation and improvement in HR without increasing the risk of complications in comparison to sinus node modification ablation, which has previously been shown to be associated with higher incidence of pacemaker implantation.

When Tree Meets Hash: Reducing Random Reads for Index Structures on Persistent Memories

Indexing structures are widely used in modern data-processing applications to support high-performance queries, and there are a variety of recent designs specifically optimized for the newly available persistent memory (PM). The primary focus of previous PM indexes is on reducing the expensive PM writes for persisting data. However, we find that in tree-based PM indexes, because of the smaller performance gap between writes and random reads on real PM devices, the read-intensive tree traversal phase dominates the overall latency. This observation calls for further optimizations on existing indexing structures for PM. In this paper, we propose Extendible Radix Tree (ERT), an efficient indexing structure for PM that significantly reduces tree heights to minimize random reads, while still maintaining fast in-node search speed. The key idea is to use extendible hashing for each node in a radix tree. This design allows us to have a relatively large fanout of the radix tree to keep the tree height small, and also to realize constant-time lookups within a node. Using extendible hashing also allows for incremental node modification without excessive writes during inserts and updates. Range queries are efficiently and robustly handled by enforcing partial ordering among the keys in the hash table of each node without introducing more hash collisions. Our experiments on both synthetic and real-world data sets demonstrate that ERT achieves up to 2.65×, 4.41×, and 2.43× speedups for search, insert, and range queries over the respectively state-of-the-art PM index.

PO-01-081 EPICARDIAL PHRENIC NERVE DEFLECTION DURING SINUS NODE MODIFICATION

Endocardial catheter ablation for sinus node modification may be difficult due to right phrenic nerve location and risk of injury. Various strategies to displace the phrenic nerve from target ablation sites have been described previously, including saline infusion and balloon catheter insufflation, all within the epicardial space. To describe a strategy to avoid phrenic nerve injury during endocardial catheter ablation for sinus node modification using a steerable catheter. N/A A 33-year-old female with a history of Behcet’s disease and AF ablations but otherwise without structural heart disease developed symptomatic inappropriate sinus tachycardia (IST) recorded on her loop recorder. Her IST was refractory to multiple drugs including flecainide, sotalol, dofetilide, and ivabradine. She had previously undergone catheter ablation for sinus node modification, which was limited due to proximity of the phrenic nerve near the intended ablation target. She presented for a repeat catheter ablation with planned epicardial access for sinus node modification. The patient presented to the EP lab in sinus rhythm with rates in the 60s. Endocardial and epicardial access were obtained under general anesthesia. The ablation catheter was advanced into the superior vena cava and right atrium, and the IST activation map during isoproterenol infusion and sites of phrenic capture were annotated (Figure A). Using a steerable sheath and a non-irrigated 4mm catheter via the epicardial access, the phrenic nerve was deflected away from the sinus node. The proximity between the endocardial and epicardial catheters was confirmed on fluoroscopy (Figure B). The phrenic nerve was checked before and after each ablation lesion. A total of 11 lesions at 30W with target contact >10 grams and target impedance drop >10 ohms was delivered for a total of 333 seconds (Figure C). Following endocardial catheter ablation, her resting sinus rates decreased to 50s. Isoproterenol infusion challenge before and after the ablation revealed blunted response in her heart rate. Her phrenic nerve remained intact with appropriate diaphragm stimulation. The patient was resumed on sotalol and discharged. Endocardial catheter ablation for IST sinus node modification may be challenging due to the phrenic nerve. Epicardial access for phrenic nerve deflection may be required.

Poly(3,4‐ethylenedioxythiophene)‐Modified Graphite Felt and Carbon Cloth Anodes for Use in Microbial Fuel Cells

AbstractAnode modification is an effective method for enhancing extracellular electron transportation and improving the power density of Microbial Fuel Cells (MFC). In this study, we decorated the surface of Carbon Cloth (CC) and Graphite Felt (GF) with a new conductive polymer, poly(3,4‐ethylenedioxyhiophene) (PEDOT), using galvanostatic electropolymerization and fabricated a CC/PEDOT and GF/PEDOT anode for MFC application. Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) analyses illustrated that the PEDOT coating improved a redox‐active surface area, high electron transfer capabilities, and lower charge‐transfer resistance of anode. These modified electrodes give enhanced MFC performances with maximum energy generation and coulombic efficiency compared with plain electrode. The morphological characteristics like higher surface area and open structure of felt and carbon material promoted microbial formation and electrochemical active area. Compared with the unmodified anode, the PEDOT anodic modification improves the current density by 6.9 times i. e., 3.813 Am−2. Thus GF/PEDOT anode excelled among the studied anodes with the synergetic effect of PEDOT coating and structural configuration, making it a potential optimum anode for MFC application.

B-PO04-135 PERCUTANEOUS AND THORACOTOMY BASED SINUS NODE ABLATION USING NANOSECOND PULSED ELECTRIC FIELDS

Sinus node (SN) modification/ ablation is a treatment option for inappropriate sinus tachycardia. It is often achieved using radiofrequency ablation which is slow given the point to point nature of treatments. Nanosecond pulse electric fields (nsPEF) are an emerging, rapid energy delivery modality which offers tissue selectivity. We explored whether acute SN ablation can be achieved with nsPEF. In two canine models, general anesthesia was administered along with paralytics. Pericardial access was obtained percutaneously in one animal and via thoracotomy in the other (Fig 1A, 1D). The area of earliest right atrial activation was identified. Electrograms were recorded before and after nsPEF energy delivery near the SN using a CellFX™ generator (Pulse Biosciences, Hayward, CA). SN ablation was achieved in both animals after delivery of 10-20 Joules of energy via nsPEF. Total duration of nsPEF sequences in each animal was <1 min. There was absence of atrial electrograms with a junctional escape rhythm in the first animal (Fig 1B, 1C) after monopolar nsPEF. Atrial activity from a left sided focus was seen in the second animal (Fig 1E, 1F) after bipolar nsPEF. Phrenic capture persisted after both sinus node ablations post paralytic withdrawal. All changes persisted beyond 30 minutes of energy delivery after which the animals were euthanized. In acute canine experiments, energy delivery via nsPEF was able to quickly ablate the SN percutaneously and via thoracotomy. nsPEF effect on cardiac tissue was demonstrated functionally without requiring histology.

Rational Anode Engineering Enables Progresses for Different Types of Organic Solar Cells

AbstractAnode modification is vital for improving device performance of organic solar cells (OSCs). PEDOT:PSS is the most widely applied hole transport layer (HTL) in OSCs. In this work, three kinds of modified HTLs, namely PEDOT:PSS‐PA, PEDOT:PSS‐TA, and PEDOT:PSS‐DA are readily prepared via simple doping of phenylethylamine derivatives into commercially available Al 4083, by modulating the number of hydroxyl groups on the adulterant molecules. All of them exhibit enhanced work functions (WFs) and conductivities. Matching with PM6:Y6 composed active layers, PEDOT:PSS‐TA based devices achieves the highest performance with a power conversion efficiency (PCE) of 17.10%, while the PM6:ITC‐2Cl system demonstrates a highest PCE of 14.17% in devices with PEDOT:PSS‐DA, and the optimal PCE of PM6:PIDTC‐T based OSCs is equal to 9.55% while the HTL is PEDOT:PSS‐PA. Further investigations reveal that the different adulterants formed various amount of hydrogen bonds in HTLs, inducing dissimilar interfacial morphology and mobility, and thus unidentical degrees of change in recombination. Afterwards, the doping strategy is extended to a newly proposed high‐performance system PM6:PY‐IT, and successfully drags its efficiency from 14.78% to 15.62%, another world‐class breakthrough for all‐polymer solar cells. In summary, this study not only achieves a series of OSCs with improved PCEs, but also delivers a deep understanding of PEDOT:PSS improvement.

A review of synthesis strategies for MOF-derived single atom catalysts

Single atom catalysts (SACs) have attracted great attention as promising catalysts that integrate the benefits of both heterogeneous and homogeneous catalysts. SACs exhibit unique properties that are otherwise difficult to achieve, such as high atom utilization efficiency, unprecedentedly high catalytic activity and selectivity. However, it still remains a great challenge to prepare stable SACs without particle aggregation and sintering. Among the various fabrication methods for SACs, metal-organic framework (MOF)-derived synthesis routes have shown great potential by taking advantage of MOFs’ high structural/chemical tunability, large surface area and high porosity. In this review, the synthesis strategies for MOF-derived SACs are comprehensively summarized and classified into five classes, metal node modification, ligand modification, guest encapsulation, migration and trapping, and others. The current challenges and future opportunities of MOF-derived SACs are further discussed. This review will be useful for the rational design of MOF-derived SACs for various catalytic reactions.

Efficacy of medical and ablation therapy for inappropriate sinus tachycardia: A single-center experience.

Effective therapy for inappropriate sinus tachycardia (IST) remains challenging with high rates of treatment failure and symptom recurrence. It is uncertain how effective pharmacotherapy and procedural therapy are long-term, with poor response to medical therapy in general. We retrospectively reviewed all patients with the diagnosis of IST at a tertiary academic medical center from 1998 to 2018. We extracted data related to prescribing patterns and symptom response to medical therapy and sinus node modification (SNM), assessing efficacy and periprocedural complication rates. A total of 305 patients with a formal diagnosis of IST were identified, with 259 (84.9%) receiving at least one prescription medication related to the condition. Beta-blockers were the most commonly used medication (n = 245), with a majority of patients reporting no change or worsening of symptoms, and poor response was seen to other medication classes. Improvement was seen significantly more often with ivabradine than beta blockers, though the sample size was limited (p = .003). Fifty-five patients (18.0% of all IST patients), mean age 32.0 ± 9.1 years, underwent a SNM procedure, with an average of 1.8 ± 0.9 procedures per patient. Acute symptomatic improvement (<6 months) was seen in 58.2% of patients. Long-term complete resolution of symptoms was seen in 5.5% of patients, modest improvement in 29.1%, and no long-term benefit was seen in 65.5% of patients. Among all medical therapies, there were high rates of treatment failure or symptom worsening in over three-quarters of patients in our study. Ivabradine was most beneficial, though the sample size was small. While most patients receiving SNM ablation for IST perceive an acute symptomatic improvement, almost two-thirds of patients have no long-term improvement, and resolution of symptoms is quite rare. AV node ablation with pacemaker implantation following lack of response to SNM offered increased success, though the sample size was limited.

Abstract 16505: Sinus Node Sparing Surgical Hybrid Thoracoscopic Ablation for Inappropriate Sinus Tachycardia: Results of a Prospective Multicenter Registry (the Susruta Registry)

Background: Medical treatment for inappropriate sinus tachycardia (IST) remains suboptimal. Radiofrequency Sinus node Modification (RFSM) has been used for managing drug-refractory symptomatic IST. Although, acute success is reasonable, it is faced with high complications and recurrence rates. A novel Sinus Node sparing surgical thoracoscopic hybrid ablation (SUSRUTA) has been recently proposed. Objective: To report outcomes of SUSRUTA for IST patients from a prospective multicenter registry. Methods: This is a multicenter, prospective registry of patients who received SUSRUTA which is SN sparing hybrid ablation using surgical thoracoscopic video-assisted epicardial ablation comprised of a RF bipolar clamp which was used for sparing the SN region (identified by endocardial 3D mapping) and isolation of superior and inferior vena cava with creation of a lateral line across the crista terminalis during IST with isoproterenol challenge. Gaps in the epicardial lesion set are filled in by endocardial RFA. Patients were treated with post op Colchicine and were enrolled in cardiac rehabilitation program. Results: Of the 139 patients, mean age was 26±4 yrs, 91% women and mean duration of IST was 40±21.5 months. 90% were on ivabradine, 86% on beta-blocker, 77% on calcium channel blocker and 77% were on class IC antiarrhythmic agent. Heart rate post-procedure was significantly lower when compared with pre-procedure (110±10 vs. 64±11 bpm, p&lt;0.0001). After a blanking period of 3 months, normal sinus rhythm was restored in 100% of patients in the hybrid group. Postop pericarditis was the most common complication in 80%(severe-4%), severe bradycardia (HR &lt;35 bpm) in 5%, pneumothorax 3.5% and pleural effusion requiring drainage in 2.1% of cases. One patient required a permanent pacemaker. Hospital length of stay was 4.5±0.8 days. At 1041±541 days follow up 94.5% (131/139) were free of symptoms after a single procedure and the 8 patients required a redo-RF catheter ablation.95% patients are off all preprocedural rate controlling medications Conclusion: SUSRUTA appears to be efficacious and safe for the treatment of symptomatic drug resistant IST.

Long-term outcomes of sinus node modification in patients with severely symptomatic drug-refractory inappropriate sinus tachycardia: a single-center experience.

The purpose of the study was to evaluate the long-term outcomes of sinus node modification (SNM) in treating patients with severely symptomatic drug-refractory inappropriate sinus tachycardia (IST). The study included 39 patients with symptomatic drug-refractory IST who have undergone SNM at Saint Louis University Hospital. Data was reviewed retrospectively. Recurrence of symptoms was assessed at 3-6-month follow-up intervals. The mean age of our cohort was 31.5 ± 11. The mean HR at diagnosis was 135 ± 25.4 beats per minute (BPM). Thirty-seven of 39 (94.8%) patients had complete resolution of symptoms. Of these 37 patients, 16 required 1 SNM, 17 patients required 2 SNM, and 4 patients required 3 SNM in order to achieve complete symptom resolution. Mean HR post-procedure was 78.6 ± 12.3 BPM. Thirteen of 39 patients required rate control medication post-procedure, all of whom were prescribed beta-blockers. Patients were followed every 3 to 6months with a mean follow-up duration of 62.3 ± 42.9months from the patient's last SNM procedure. Thirteen of those 37 patients (35.1%) developed intermittent symptomatic bradycardia requiring permanent pacemaker implantation. Two of the 39 patients had phrenic nerve injury, and 6 patients had post-procedure pericarditis. This study provides additional information to the limited dataset available in the literature and shows that SNM might provide patients with long-term symptomatic relief bearing in mind the potential increased risk for the need for permanent pacing.

Pseudoaneurysm of thoracic aorta presenting as inappropriate sinus tachycardia: a case report

BackgroundPseudoaneurysm of thoracic aorta as a complication of blunt trauma to the chest, can present with a variety of symptoms due to mass compression effect. Here we report the first pseudoaneurysm of thoracic aorta presenting with chronic cough and inappropriate sinus tachycardia. The purpose of this case report is to highlight pseudoaneurysm of thoracic aorta as a rare differential diagnosis for inappropriate sinus tachycardia.Case presentationHere we report a case of 29-year-old white woman, a nurse, with history of a motor vehicle accident. She initially presented to medical attention with inappropriate sinus tachycardia 2 years following the motor vehicle accident during her pregnancy. Six years later she underwent sinoatrial node modification after failing a number of medications. Days prior to the ablation she developed a mild cough which became constant within a week following ablation. A computed tomography scan of her chest performed as part of a workup revealed an outpouching of the inferomedial aspect of the aortic arch, which was compressing her left main bronchus. She underwent arch repair surgery and recovered without complications. Four years later she presented with significant symptomatic sinus bradycardia requiring pacemaker placement.ConclusionsThis is the first reported case of thoracic pseudoaneurysm of aorta presenting with inappropriate sinus tachycardia due to compression of the vagal nerve and cough as a result of the left main bronchus compressive effect; it highlights the importance of considering structural abnormalities in a differential diagnosis of inappropriate sinus tachycardia before any interventions.

Pore-Surface Engineering by Decorating Metal-Oxo Nodes with Phenylsilane to Give Versatile Super-Hydrophobic Metal-Organic Frameworks (MOFs).

Hydrophobization of metal-organic frameworks (MOFs) is important to push forward their practical use and thus has attracted increasing interest. In contrast to the previous reports, which mainly focused on the modification of organic ligands in MOFs, herein, we reported a novel strategy to decorate the metal-oxo nodes of MOFs with phenylsilane to afford super-hydrophobic NH2 -UiO-66(Zr), which shows highly improved base resistance and holds great promise in versatile applications, such as organic/water separation, self-cleaning, and liquid-marble fabrication. This work demonstrates the first attempt at metal-oxo node modification for super-hydrophobic MOFs, advancing a new concept in the design of MOFs with controlled wettability for practical applications.

Pore‐Surface Engineering by Decorating Metal‐Oxo Nodes with Phenylsilane to Give Versatile Super‐Hydrophobic Metal–Organic Frameworks (MOFs)

AbstractHydrophobization of metal‐organic frameworks (MOFs) is important to push forward their practical use and thus has attracted increasing interest. In contrast to the previous reports, which mainly focused on the modification of organic ligands in MOFs, herein, we reported a novel strategy to decorate the metal‐oxo nodes of MOFs with phenylsilane to afford super‐hydrophobic NH2‐UiO‐66(Zr), which shows highly improved base resistance and holds great promise in versatile applications, such as organic/water separation, self‐cleaning, and liquid‐marble fabrication. This work demonstrates the first attempt at metal‐oxo node modification for super‐hydrophobic MOFs, advancing a new concept in the design of MOFs with controlled wettability for practical applications.

Clinical Outcomes and Complications of Ablative Therapy of Inappropriate Sinus Tachycardia: A Case Series

Background: Sino-atrial node modification by radiofrequency ablation (RFA) is one of the management options in patients with inappropriate sinus tachycardia (IST). The broad application of RFA is limited owing to perceived low success and high complication rates.

Tuning the properties of metal-organic framework nodes as supports of single-site iridium catalysts: node modification by atomic layer deposition of aluminium.

The metal-organic framework NU-1000, with Zr6-oxo, hydroxo, and aqua nodes, was modified by incorporation of hydroxylated Al(iii) ions by ALD-like chemistry with [Al(CH3)2(iso-propoxide)]2 followed by steam (ALD = atomic layer deposition). Al ions were installed to the extent of approximately 7 per node. Single-site iridium diethylene complexes were anchored to the nodes of the modified and unmodified MOFs by reaction with Ir(C2H4)2(acac) (acac = acetylacetonate) and converted to Ir(CO)2 complexes by treatment with CO. Infrared spectra of these supported complexes show that incorporation of Al weakened the electron donor tendency of the MOF. Correspondingly, the catalytic activity of the initial supported iridium complexes for ethylene hydrogenation increased, as did the selectivity for ethylene dimerization. The results of density functional theory calculations with a simplified model of the nodes incorporating Al(iii) ions are in qualitative agreement with some catalyst performance data.

Temporal sinus node modification by high-dose continuous intravenous administration of landiolol in a patient with persistent inappropriate sinus tachycardia

A 20-year-old woman underwent an electrophysiological study for drug-resistant persistent inappropriate sinus tachycardia (IST). Use of a high-dose continuous intravenous administration of landiolol, a short-acting beta-adrenoreceptor blocker, made the patient׳s heart rate suddenly drop with a slight change in the P-wave morphology. Three-dimensional right atrial (RA) activation mapping revealed that the earliest activation site moved 8mm to a lower anterior site around the high lateral RA. Radiofrequency energy applied to the earliest activation site during tachycardia was successful. A temporal sinus node modification with landiolol administration was useful for mapping and for safe catheter ablation of IST.

Parameter-Level Data Flow Modeling Oriented to Product Design Process

In this paper, a method of data flow modeling for a product design process oriented to data parameter is proposed. The data parameters are defined, which are classified as the basic data parameters and complex data parameters. The mechanism of the mapping relationship between different forms of documents and some basic data parameters, and a data transmission based on parameters, are constructed. Aiming at the characteristics of the iterative design process, the parameters version mechanism including node modification and iteration information is proposed. The data parameters transmission relationships are represented by a parameters network model (PNM) based on a directed graph. Finally, through the table of data parameters mapping onto the workflow node and PNM, the data ports and data links in the data flow model are generated automatically by the program. Validation in the 15-meter-diameter S/Ka frequency band antenna design process of the “Reflector, Back frame and Center part design” data flow model shows that the method can effectively shorten the time of data flow modeling and improve the data transmission efficiency.