Roadmap on thermoelectricity.

The increasing energy demand and the ever more pressing need for clean technologies of energy conversion pose one of the most urgent and complicated issues of our age. Thermoelectricity, namely the direct conversion of waste heat into electricity, is a promising technique based on a long-standing physical phenomenon, which still has not fully developed its potential, mainly due to the low efficiency of the process. In order to improve the thermoelectric performance, a huge effort is being made by physicists, materials scientists and engineers, with the primary aims of better understanding the fundamental issues ruling the improvement of the thermoelectric figure of merit, and finally building the most efficient thermoelectric devices. In this Roadmap an overview is given about the most recent experimental and computational results obtained within the Italian research community on the optimization of composition and morphology of some thermoelectric materials, as well as on the design of thermoelectric and hybrid thermoelectric/photovoltaic devices.

All-Oxide p-n Junction Thermoelectric Generator Based on SnOx and ZnO Thin Films.

Achieving thermoelectric devices with high performance based on low-cost and nontoxic materials is extremely challenging. Moreover, as we move toward an Internet-of-Things society, a miniaturized local power source such as a thermoelectric generator (TEG) is desired to power increasing numbers of wireless sensors. Therefore, in this work, an all-oxide p-n junction TEG composed of low-cost, abundant, and nontoxic materials, such as n-type ZnO and p-type SnOx thin films, deposited on borosilicate glass substrate is proposed. A type II heterojunction between SnOx and ZnO films was predicted by density functional theory (DFT) calculations and confirmed experimentally by X-ray photoelectron spectroscopy (XPS). Moreover, scanning transmission electron microscopy (STEM) combined with energy-dispersive X-ray spectroscopy (EDS) show a sharp interface between the SnOx and ZnO layers, confirming the high quality of the p-n junction even after annealing at 523 K. ZnO and SnOx thin films exhibit Seebeck coefficients (α) of ∼121 and ∼258 µV/K, respectively, at 298 K, resulting in power factors (PF) of 180 µW/m K2 (for ZnO) and 37 µW/m K2 (for SnOx). Moreover, the thermal conductivities of ZnO and SnOx films are 8.7 and 1.24 W/m K, respectively, at 298 K, with no significant changes until 575 K. The four pairs all-oxide TEG generated a maximum power output (Pout) of 1.8 nW (≈126 µW/cm2) at a temperature difference of 160 K. The output voltage (Vout) and output current (Iout) at the maximum power output of the TEG are 124 mV and 0.0146 µA, respectively. This work paves the way for achieving a high-performance TEG device based on oxide thin films.

Economic Convenience of Hybrid Thermoelectric-Photovoltaic Solar Harvesters.

Over the last few years, a growing interest has surfaced about the possibility of enhancing solar harvester efficiency by coupling photovoltaic (PV) cells with thermoelectric generators (TEGs). To be effective solutions, hybrid thermoelectric-photovoltaic (HTEPV) solar harvesters must not only increase the solar conversion efficiency but should also be economically competitive. The aim of this paper is to estimate the profitability of HTEPV solar harvesters with no reference to specific materials, relating it instead to their physical properties only and thus providing a tool to address research effort toward classes of HTEPV systems able to compete with current PV technologies. An economic convenience index is defined and used to assess the economic sustainability of hybridization. It is found that, although hybridization often leads to enhanced solar power conversion, power costs (USD/W) may not always justify HTEPV deployment at the current stage of technology. An analysis of the cost structure shows that profitability requires largely enhanced thermoelectric stages, concentrated solar cells, or PV materials with favorable temperature efficiency coefficients, such as perovskite solar cells.

Microvascular grafting to enhance perfusion in colonic long-segment oesophageal reconstruction.

PURPOSE: Oesophagectomy with long-segment colon reconstruction is the first-line treatment when the stomach is not available. Supercharging of the newly formed conduit can improve vascular function utilizing intraoperative perfusion imaging system, following thoracoscopic oesophagectomy for distal-oesophageal and gastroesophageal junction cancer. The purpose of this study is to examine the safety and efficacy of microvascular augmentation of left colonic interposition following oesophagectomy for oesophageal cancer. METHODS: A retrospective analysis of 156 consecutive oesophagectomies between January 2016 and July 2018 was performed. All oesophagectomies involving left colon interposition with microvascular augmentation were included in the study. In all cases, oesophageal mobilization was performed thoracoscopically in prone position and the left colon was used as neo-oesophagus in an isoperistaltic fashion. Conduit perfusion was assessed with the Spy system and neck supercharging was performed using microsurgical technique. RESULTS: A total of n = 5 (3.2%) patients were identified. Two cases had delayed and 3 had immediate reconstruction. The conduit was microsurgically augmented in 3 cases with both venous and arterial anastomoses (supercharging) and in 2 cases with venous anastomosis only (superdrainage). No anastomotic leak was identified. One case developed left recurrent laryngeal nerve palsy with associated aspiration pneumonia. CONCLUSIONS: Supercharged colonic interposition is a safe way of oesophageal reconstruction when long-segment interposition graft is needed. In oesophageal cancer and in the absence of a viable stomach with intact gastroepiploic arcade, it should be considered a feasible option with favourable outcomes, when the expertise and facilities are available. Use of intraoperative perfusion imaging reveals improved conduit blood supply post-supercharging.

Completely Minimally Invasive Esophagectomy Versus Hybrid Esophagectomy for Esophageal and Gastroesophageal Junctional Cancer: Clinical and Short-Term Oncological Outcomes.

BACKGROUND: Minimally invasive surgery for resectable esophageal and gastroesophageal junctional (GEJ) cancer significantly reduces morbidity when compared with open surgery, as is evident from published landmark trials. Comparison of outcomes between hybrid esophagectomy (HE) and completely minimally invasive esophagectomy (CMIE) remains unclear. OBJECTIVE: We aimed to ascertain whether CMIE is associated with less postoperative complications compared with HE without oncological compromise. METHODS: All consecutive two-stage HEs and CMIEs performed between 2016 and 2018 were included. All procedures were performed with an intrathoracic anastomosis. Primary clinical outcomes were pulmonary infective and overall complications within 30 days of surgery, while primary oncological outcomes included overall survival (OS) and disease-free survival (DFS) at both 6 months and to date. Secondary outcomes included intraoperative variables and postoperative clinical parameters. RESULTS: Overall, 98 patients had CMIEs and 49 patients had HEs. There were no baseline differences between the two groups. Thirty-day postoperative pulmonary infection rates were lower in the CMIE group compared with the HE group (12.2% vs. 28.6%; p = 0.014), and 30-day overall postoperative complication rates were also lower following CMIE (35.7% vs. 59.2%; p = 0.007). OS and DFS were similar between the two groups at 6 months (p = 0.201 and p = 0.109, respectively). CONCLUSIONS: CMIE is associated with less pulmonary infective and overall postoperative complications compared with HE for resectable esophageal and GEJ cancer. No intergroup difference was observed regarding short-term survival and cancer recurrence in patients undergoing CMIE and HE. A randomized controlled trial comparing the two operative approaches is required to validate these findings.

Intrathoracic hand-sewn esophagogastric anastomosis in prone position during totally minimally invasive two-stage esophagectomy for esophageal cancer.

Utilization of totally minimally invasive esophagectomy for cancer is on the rise. Esophagogastric anastomosis is mechanically or robotically performed routinely; little report exists of hand-sewn esophagogastric anastomosis. This is the largest so far study with thoracoscopic hand-sewn esophagogastric anastomosis during fully minimally invasive two-stage esophagectomy for esophageal cancer in prone position. Consecutive two-stage totally minimally invasive esophagectomies for cancer were performed by one surgical team, from September 2016 to March 2019. All operations were technically identical in terms of patient positioning, surgical approach, extend of lymphadenectomy and type of anastomosis formed. Primary end points were anastomotic leak and anastomotic stricture rate, while secondary end points were 30-day and 90-day mortality rates. From the overall n = 80 patients, n = 67 were males, while n = 13 were females. Mean age was 64.6 years. Mean length of stay was n = 14 days. There were no conversions to open. Mean operating time was 420 minutes with no blood loss over 200 mL noted. Pulmonary and cardiac complication rate was 23.75% and 2.5%, respectively. Anastomotic leak rate was 2.5%. Anastomotic strictures were seen in 12.5% of cases. 30-day and 90-day mortality rate was 2.5% and 5%, respectively, with none accounted for ischemic conduit complications. Intrathoracic anastomosis in totally minimally invasive esophagectomy is challenging and accountable for most of the mortality associated with the procedure. In thoracoscopic two-stage esophagectomy, a mechanical anastomosis is usually preferred; this is believed to be due to the complexity of manual anastomosis associated with the thoracoscopic approach. We aim to present our series of completely hand-sewn intrathoracic anastomosis utilizing a totally minimally invasive approach with favorable outcomes. With this study, reproducibility of the anastomosis is shown that can potentially favor a change in the practice of esophageal surgeons worldwide.

Prone position thoracoscopic management of neck chyle leak following major head and neck surgery. A case series.

Chyle leak is a major compication following head and neck surgery, with reported incidence of 0.5% up to 8.3% in published literature. Cervical chyle leak may be challenging to manage with significant morbidity, resulting from extensive fluid and nutritional losses. This manuscript presents four cases of cervical chyle leak after head and neck surgery. Cervical thoracic duct injury had been identified intra-operatively. Conservative treatment failed to reduce chylous output post-operatively. All patients were offered thoracocscopic thoracic duct ligation in prone position; thoracic duct was dissected above the right diaphragm and ligated. Immediate resolution of their symptoms followed, with no recurrence at the follow-up period. Intra-operative repair of cervical thoracic duct remains controversial, while when identified early reduces the following comorbidities. Conservative management addresses reduction of chylous output, while amplifying hydration and alimentation. Thoracoscopic thoracic duct ligation offers a safe and feasible treatment for cervival chyle leak following head and neck surgery with all the advances of minimally-invasive surgery. KEY WORDS: Chyle leak, Head and Neck Surgery, Thoracoscopic, Thorasic Duct, Ligation, Minimally-Invasive.

Self-powered broadband photo-detection and persistent energy generation with junction-free strained Bi2Te3 thin films.

We experimentally demonstrate efficient broadband self-powered photo-detection and power generation in thin films of polycrystalline bismuth telluride (Bi2Te3) semiconductors under inhomogeneous strain. The developed simple, junction-free, lightweight, and flexible photo-detectors are composed of a thin active layer and Ohmic contacts on a flexible plastic substrate, and can operate at room temperature and without application of an external bias voltage. We attribute the observed phenomena to the generation of an electric field due to a spontaneous polarization produced by strain gradient, which can separate both photo-generated and thermally-generated charge carriers in bulk of the semiconductor material, without a semiconductor junction. We show that the developed photo-detectors can generate electric power during both the daytime and the nighttime, by either harnessing solar and thermal radiation or by emitting thermal radiation into the cold sky. To the best of our knowledge, this is the first demonstration of the power generation in a simple junction-free device under negative illumination, which exhibits higher voltage than the previously used expensive commercial HgCdTe photo-diode. Significant improvements in the photo-detector performance are expected if the low-charge-mobility polycrystalline active layer is replaced with high-quality single-crystal material. The technology is not limited to Bi2Te3 as the active material, and offers many potential applications in night vision, wearable sensors, long-range LIDAR, and daytime/nighttime energy generation technologies.

Minimally invasive esophagectomy for esophageal cancer in octogenarians. Clinical and oncological outcomes.

PURPOSE: Studies on patients undergoing esophagectomy for esophageal cancer have shown that thoracic and abdominal surgery may be performed safely in patients without an uppermost age cut-off. The aim of this study was to evaluate the morbidity and mortality of radical minimally invasive esophagectomy for cancer in patients over 80 years old. METHODS: A retrospective analysis of prospectively collected data over a period of 4 years was conducted. During the study period 184 esophagectomies were performed. A total of 12 octogenarians that underwent Minimally Invasive Esophagectomy (MIE) for cancer were included in the study. Our results were compared to the UK national outcomes as presented in the National Esophago-Gastric Cancer Audit (NOGCA) 2017 report. RESULTS: Median overall survival (OS) was 16.5 months (range: 6-38) and progression-free survival (PFS) 14.5 months (tange:3-38). 30-and 90-day postoperative mortality was zero. Postoperative complications included chest infection (CI) in 4 (33.3%) patients, anastomotic leakage (AL) in 3 (25%) and atrial fibrillation in 2 (16.7%). CONCLUSIONS: MIE should therefore be considered as an effective treatment strategy even in elderly patients over 80 years of age.

Hybrid Minimally-invasive Esophagectomy for Esophageal Cancer: Clinical and Oncological Outcomes.

BACKGROUND/AIM: Esophagectomy is a major surgical procedure associated with a significant risk of morbidity and mortality that has traditionally been performed by an open approach. Although minimally invasive procedures for benign esophageal disease have been widely accepted worldwide, they have not yet been established for the treatment of malignancy. PATIENTS AND METHODS: A total of 137 consecutive hybrid esophagectomies for cancer were performed by the same surgical team. Surgical approach included either 2-stage or 3-stage hybrid minimally-invasive esophagectomy. RESULTS: Median age of patients was 64 years. Respiratory complication and anastomotic leak rates were 16.78% and 9.48%, respectively. Median follow-up was 48 months with median overall survival and disease free survival were 58 and 48 months, respectively. CONCLUSION: Advances in minimally invasive surgery can benefit patients with esophageal cancer, mainly by reducing post-operative respiratory complications. Hybrid esophagectomy is safe and feasible in tertiary esophago-gastric centers with vast expertise that can lead to improved clinical and oncological outcomes.

Reinforcement of intrathoracic oesophago-gastric anastomosis with fibrin sealant (Tisseel®) in oesophagectomy for cancer: A prospective comparative study.

PURPOSE: Fibrin sealant (Tisseel) is a human protein and thrombin soluble fibrinogen that has been indicated for reinforcement of gastro-intestinal anastomoses to prevent leakage. The objective of this study is to examine the impact of fibrin sealant regarding anastomotic leak, following Ivor-Lewis procedure. METHODS: This is a prospective comparative study on 2-stage oesophagectomy for cancer of the distal oesophagus or oesophagogastric junction. N = 57 individuals were randomly subjected; n = 22 patients to Tisseel in combination to surgical anastomosis versus n = 35 patients to surgical anastomosis alone. The test of probability was assessed through Chi-Square, independent samples paired T-Test and Log-Rank analysis. RESULTS: Of the 57 cases included, 56 underwent hybrid and 1 open oesophagectomy. In the Tisseel group, n = 5(22.7%) developed anastomotic leak comparing to n = 3(8.6%) of the control group. No statistically significant difference in leak rate was shown between the two groups; the test of probability was rejected. CONCLUSIONS: Our results are not supportive of Tisseel tissue sealing property on the intrathoracic oesophago-gastric anastomosis and fibrin sealant's use cannot be justified.

Preservation of replaced left hepatic artery during 3D laparoscopic totally minimally invasive esophagectomy for cancer.

Preserving a replaced left hepatic artery may be feasible and safe during 3D laparoscopic totally minimally invasive esophagectomy. Avoidance of conversion to an open procedure may be achieved after careful dissection of the celiac trunk lymph nodes, expertise and the visual advantage that 3D vision offers.

Prognostic Value of Subcarinal Lymph Nodes in Minimally Invasive Esophagectomy for Cancer.

BACKGROUND/AIM: Surgical resection for esophageal cancer has remained the gold-standard therapy provided worldwide. Subcarinal lymph-nodes are classified as peri-esophageal nodes and their dissection may be performed during a 2- or 3-stage esophagectomy. The necessity and prognostic value of subcarinal lymphadenectomy is still debatable. The purpose of this study was to investigate the rate of invaded subcarinal lymph-nodes out of the total lymph-nodes resected. Detection of invaded nodes was correlated with clinical staging and tumor differentiation. PATIENTS AND METHODS: This is a retrospective analysis of consecutive esophagectomies for cancer, performed in a UK tertiary center. The study was conducted over a 3-year period. RESULTS: The rate of subcarinal lymph-node invasion was extremely low according to the results of our analysis. CONCLUSION: Lymphadenectomy is not devoid of clinical impact on patients and therefore, the decision should actually be the outcome of a dynamic balance between complications and survival benefit.

Over-the-scope-clip treatment of gastrobronchial fistula following minimally invasive oesophagectomy: a novel approach.

Gastrobronchial fistulae (GBF) following minimally invasive oesophagectomy (MIO) is a rare entity, with an estimated incidence of 0.3-1.5% according to the published literature. It could present with persistent cough (Ohno's sign), chest pain, haemoptysis and recurrent pneumonia. Barium swallow examination remains the most sensitive investigation in 78% of the cases; the main stay of management is surgical and in some cases endoscopic (stent insertion). We report a rare case of a GBF 1 month after two-stage MIO for cancer of the gastro-oesophageal junction, which was successfully treated for the first time with an over-the-scope-clip.

Laparoscopic repair of Amyand's hernia complicated with acute appendicitis. Report of a case.

The presence of vermiform appendix in an inguinal hernia sac is known as Amyand's hernia. Amyand's hernia complicated with acute appendicitis is an extremely rare entity with challenging diagnosis and large debate about the optimal treatment option. We report a case of a 58-year-old man presenting to the Emergency Department with an incarcerated right inguinal hernia. At laparoscopy, an inflamed appendix was identified within the inguinal canal, representing an indirect Amyand's hernia. A laparoscopic appendicectomy was performed followed by a trans-abdominal pre-peritoneal mesh repair of the aforementioned hernia. We report this rare clinical entity raising physicians' awareness to include acute appendicitis within an Amyand's hernia in the differential diagnosis of incarcerated inguinal hernias, along with a successful minimally invasive surgical approach.

Minimally Invasive Circumferential Hiatal Dissection for the Treatment of Adenocarcinoma of the Distal Esophagus and Esophago-gastric Junction: Technical Considerations Combined With Histopathological Outcomes.

BACKGROUND/AIM: Circumferential resection margin involvement is an independent prognostic factor in patients with adenocarcinoma of the distal esophagus and esophago-gastric junction. However, there is currently no consensus on the extent and the technique of hiatal dissection. We describe a minimally invasive technique of circumferential hiatal dissection for adenocarcinoma of the distal esophagus and esophago-gastric junction with its related histopathological results. PATIENTS AND METHODS: A prospective study of 40 consecutive patients undergoing hybrid (laparoscopic/thoracotomic) or totally minimally invasive Ivor-Lewis esophagogastrectomy over a period of 21 months was conducted. Dissection of the hiatus included peri-esophageal surrounding tissues in a cylindrical fashion maximizing the distance from the oesophageal wall. Crural muscle fibers and pleura bilaterally, pericardial fat anteriorly and pre-aortic tissue posteriorly were excised en bloc. Histopathological results particularly focused on involvement of the circumferential resection margin. Neoadjuvant chemotherapy was given to 24 (60%) patients. RESULTS: Complete histological clearance (R0) was achieved in 92.5% (n=37) according to the criteria of the College of American Pathologists and in 87.5% (n=35) according to those of the Royal College of Pathologists. In pT3 tumors (n=22), the circumferential resection margin was negative in 20 patients (91%) according to the College of American Pathologists, and in 17 (77%) according to the Royal College of Pathologists. CONCLUSION: Adoption of this safe and reproducible technique might reduce the incidence of circumferential resection margin involvement and improve pathological outcomes. In addition, there may be positive implications for training and quality control.

Thoracoscopic total esophagogastrectomy with supercharged colon interposition for the treatment of esophageal adenocarcinoma in situs inversus.

Background: Esophagectomy in situs inversus is challenging. With long-segment supercharged reconstruction, it becomes more perplexing and multidisciplinary surgical skills are needed. Challenges met and the surgical technique used is presented in this case report. Methods: The case of a 49-year old patient with situs inversus abdominus and a locally advanced distal esophageal adenocarcinoma extending to the stomach is presented. Results: Following neoadjuvant chemotherapy and due to inability to use the stomach as a conduit, a thoracoscopic total esophagogastrectomy with long-segment reconstruction was performed. The conduit used was the left colon and was supercharged with venous and arterial anastomoses in the neck. Conduit perfusion, as assessed by the Spy system revealed marked improvement post supercharging. No anastomotic leak was noted and oral diet was started on day 4. On day 26 the patient developed pneumonia necessitating intubation that was declined. Organ support was withheld with patient death at day 29. Conclusion: In long-segment esophageal reconstruction with supercharged colon, although thoracoscopy is feasible, laparoscopy is found unsafe. Careful preoperative planning and colon assessment via computed tomography(CT) colonography/angiography and a multidisciplinary team approach is recommended. Adjuncts to assess conduit perfusion like the Spy system are helpful. Supercharging the long colonic conduit is a way of minimizing ischemia-related complications.

Transmural migration of azygous vein Hem-O-lok clip causing food bolus 3 months following uneventful minimally invasive oesophagectomy.

BACKGROUND: Hem-o-lok clips are widely deployed in various laparoscopic and robotic operations. Their migration is not very common and majority of reported cases are limited to biliary, prostatic and vesico-urethral cases. METHODS: Herein, we would like to report the first case of transmural migration of Hem-o-lok clip from azygous vein stump following totally minimally invasive two-stage oesophagectomy for squamous cell carcinoma of the distal oesophagus, into the gastric conduit 3-months following uneventful discharge. The patient presented with 5-days history of worsening dysphagia. RESULTS: The subsequent gastroscopy revealed normal gastric conduit with two Hem-o-lok clips containing the azygous vein stump within its lumen at the level of the oesophago-gastric anastomosis, propagating a food bolus obstruction. The foreign body was successfully removed and the patient was discharged the same day without any complications at 5 months follow up. CONCLUSION: Hem-o-lok clip migration trends to be a well-established event. However, their mechanism and exact incidence remains elusive to this date. To the best of our knowledge, their migration in oesophageal cancer surgery has not been reported.

Left Gastric Artery Embolisation for the Treatment of Obesity: a Systematic Review.

BACKGROUND: Endovascular left gastric artery (LGA) embolisation has gained significant attention in the treatment of obesity/morbid obesity and reduction of ghrelin. The objective of this systematic review is to evaluate the recent literature, strengths, limitations and practical aspects of this new procedure in combination with its physiological and anatomical paradigm. METHODS: A systematic electronic search of literature from 1966 to June 2017 in Medline, CINHAL, Embase, Scopus and Cochrane library in English language and adult subjects was conducted. This search was conducted in accordance with Preferred Reporting in Systematic Review and Meta-Analysis (PRISMA) guidelines. Quality assessment of the articles was performed, using Oxford critical appraisal skills programme (CASP), and their recommendation for practice was examined through National Institute for health Care Excellence (NICE). Inter-related reliability (Cronbach's Alpha) was assessed between the two independent reviewers. RESULTS: A total of n = 62 individuals were subjected to LGA embolisation. At 1-3 months, 7-11% and, at 12 months, 2% weight reduction was associated with ghrelin concentration reduction of 36% at 6 months. There was Haemoglobin A1c reduction (7.4 to 6.3%) and improved quality of life (SF-36 questionnaire) at 6 months (9.5 points) (range, 3.2-17.2). Despite immediate epigastric pain and mucosal ulceration, no long-term adverse outcome was identified. The overall length of stay was 2-3 days. CONCLUSIONS: The outcome of this review (level of evidence 3) suggests LGA embolisation is feasible and effective and perhaps a safe procedure in the treatment of obesity and reduction of ghrelin. However, further trials are highly advocated.

Gastric conduit obstruction due to gastroduodenal compression: a new complication post-Ivor-Lewis oesophagectomy.

INTRODUCTION: Oesophagectomy for oesophageal carcinoma carries a high risk of significant morbidity and mortality. Delayed gastric emptying is a relatively common complication following this procedure. A variety of medical, surgical and endoscopic strategies have been described to manage it. The vast majority of cases are related to post-operative pyloric dysfunction and are amenable to conventional management strategies. PATIENTS AND METHODS: We present a new case of a patient with a duodenal hiatus hernia resulting in extrinsic gastroduodenal compression by the massively distended gastric conduit as a cause of gastric outlet obstruction following laparoscopic-assisted Ivor-Lewis oesophagectomy 2 years previously. RESULTS AND CONCLUSIONS: Surgical repair of the hiatus hernia restored the post-oesophagectomy anatomy and resolved this patient's symptoms where conventional management of post-oesophagectomy gastric outlet obstruction had failed on multiple occasions. Most cases of delayed gastric emptying post-oesophagectomy occur as a result of pyloric dysfunction and can be managed using a combination of prokinetics, surgical intervention or more commonly, endoscopic dilatation. Other potential causes and therefore investigative and management strategies should be considered in patients who repeatedly fail conventional management. We offer an alternative diagnosis that may be considered in these patients and present a novel approach to their investigation and management.