Optimization of Nano-Additive Characteristics to Improve the Efficiency of a Shell and Tube Thermal Energy Storage System Using a Hybrid Procedure: DOE, ANN, MCDM, MOO, and CFD Modeling

Using nano-enhanced phase change material (NePCM) rather than pure PCM significantly affects the melting/solidification duration and the stored energy, which are two critical design parameters for latent heat thermal energy storage (LHTES) systems. The present article employs a hybrid procedure based on the design of experiments (DOE), computational fluid dynamics (CFD), artificial neural networks (ANNs), multi-objective optimization (MOO), and multi-criteria decision making (MCDM) to optimize the properties of nano-additives dispersed in a shell and tube LHTES system containing paraffin wax as a phase change material (PCM). Four important properties of nano-additives were considered as optimization variables: volume fraction and thermophysical properties, precisely, specific heat, density, and thermal conductivity. The primary objective was to simultaneously reduce the melting duration and increase the total stored energy. To this end, a five-step hybrid optimization process is presented in this paper. In the first step, the DOE technique is used to design the required simulations for the optimal search of the design space. The second step simulates the melting process through a CFD approach. The third step, which utilizes ANNs, presents polynomial models for objective functions in terms of optimization variables. MOO is used in the fourth step to generate a set of optimal Pareto points. Finally, in the fifth step, selected optimal points with various features are provided using various MCDM methods. The results indicate that nearly 97% of the Pareto points in the considered shell and tube LHTES system had a nano-additive thermal conductivity greater than 180 Wm−1K−1. Furthermore, the density of nano-additives was observed to be greater than 9950 kgm−3 for approximately 86% of the optimal solutions. Additionally, approximately 95% of optimal points had a nano-additive specific heat of greater than 795 Jkg−1K−1.

Hybrid Technique for Acute on chronic Lower Limb Ischemia, A single centre study

Background Several methods have been postulated for the treatment of acute on chronic lower limb ischemia; among them, the hybrid procedure (combined open thrombectomy and angioplasty) is gaining popularity .It is aimed at clearing the vessel and treating the underlying vessel lesion in one step. Patients and Methods A total of 23 patients admitted to the vascular department were eligible for inclusion in this study. They were subjected to thromboembolectomy, followed by endovascular balloon dilatation with or without stenting. Data regarding the risk factors, procedure success, and complications were recorded. Results Hybrid procedures showed 91.6% immediate technical success and 82.6% primary limb salvage rate up to 6 months with accepted minor complications. and no major complications Conclusion The hybrid procedure provides an accepted outcome in treating immediately limb- threatening acute on chronic lower limb ischemia.

Hybrid Procedure for Coexistence of Coarctation of the Aorta and Aberrant Right Subclavian Artery: A Case Report and Review of the Literature

Background: Coarctation of the aorta (CoA) can either present alone as an isolated condition or in association with other aortic arch or cardiac anomalies. One percent of patients with CoA have concomitant an aberrant right subclavian artery (ARSA). Purpose: We report the case of a 35-year-old woman with uncontrolled hypertension who was found to have CoA and ARSA. Results: The patient was treated successfully using a hybrid procedure comprising ARSA ligation and subclavian to carotid transposition, followed by thoracic endovascular aortic repair. Conclusions: Patients with CoA should be carefully studied, considering the possible coexistence of other congenital aortic arch defects, such as ARSA. Hybrid repair is a safe and effective approach for this condition.

Catheter, surgical, or hybrid procedure: what future for atrial fibrillation ablation?

Background The debate on the best treatment strategy for atrial fibrillation (AF) has expanded following the introduction of the so-called “hybrid procedure” that combines minimally invasive epicardial ablation with endocardial catheter ablation. However, the advantage of the hybrid approach over conventional epicardial ablation remains to be established. Methods From June 2008 to December 2020, 609 surgical AF ablation procedures through a right minithoracotomy were performed at our institution. From 2008 to 2011, a unipolar radiofrequency (RF) device was used, whereas from 2011 to 2020 a bipolar RF device was used. In addition, between September 2016 and April 2017, 60 patients underwent endocardial completion of epicardial linear ablation. In 30 of these latter patients, surgical isolation of the Bachmann’s bundle (BB) was also performed. Starting from 2021, surviving patients at follow-up were asked to undergo electrocardiographic evaluation and left ventricular function assessment and to complete a questionnaire addressing quality of life and predisposing factors for recurrent AF. Results The ablation procedure was completed in all patients. Upon discharge, 30 (4.9%) patients showed recurrence of AF, whereas the remaining patients (95.1%) were in sinus rhythm. All patients in whom a hybrid approach was used either with or without BB ablation were discharged in sinus rhythm. After a mean follow-up of 74 months, 122 (20%) patients developed recurrent AF, including 19.9% in whom a unipolar RF device was used, 21% in whom a bipolar RF device was used, 23% who had undergone a hybrid procedure without BB ablation and 3.3% who had undergone a hybrid procedure with BB ablation. On multivariate analysis, reduced left ventricular ejection fraction, worsening of European Heart Rhythm Association symptom class, and cognitive impairment or depression during follow-up were found to be significantly associated with AF recurrence. Conclusions Surgical AF ablation through a right minithoracotomy is safe and may allow the creation of additional linear lesions, particularly in the BB. The placement of adjunctive linear lesions in the setting of a hybrid procedure can be more effective in reducing the risk for AF recurrence than isolated surgical ablation or hybrid ablation without the addition of further linear lesions, with no incremental risk to the patient.

One-stage supraclavicular hybrid procedure for type B aortic dissection involving three rare anatomical anomalies: a case report and literature review

Managing type B aortic dissection (TBAD) involving Kommerell’s diverticulum (KD), aberrant right subclavian artery (ARSA), and isolated left vertebral artery (ILVA), is extremely challenging. As treatment, we described a one-stage hybrid technique combined with thoracic endovascular aortic repair (TEVAR) with open surgery through a supraclavicular incision. A 57-year-old man with TBAD and the three anomalies successfully underwent hybrid TEVAR. A side-to-side artificial bypass between the ARSA and the right common carotid artery was established through a right supraclavicular incision before TEVAR. The release of the stent-graft was designed from the distal aortic ostium to the left common carotid artery (LCCA) to cover the ILVA, ARSA, and left subclavian artery (LSA). Then, the ILVA and LSA were transposed to the LCCA through a left supraclavicular incision. Intraoperative angiography confirmed complete false lumen exclusion and KD, with all branches patent and without endoleaks. Computed tomography angiography 7 days and 1 year postoperatively demonstrated well-perfused ARSA, LSA, and ILVA, and a fully expanded stent-graft with no endoleaks, migration, disconnection, or stenosis. TBAD involving KD, ARSA, and ILVA in one case is rare. This is the first report to treat this pathology with a one-stage supraclavicular hybrid procedure.