A US perspective on closing the carbon cycle to defossilize difficult-to-electrify segments of our economy.

Electrification to reduce or eliminate greenhouse gas emissions is essential to mitigate climate change. However, a substantial portion of our manufacturing and transportation infrastructure will be difficult to electrify and/or will continue to use carbon as a key component, including areas in aviation, heavy-duty and marine transportation, and the chemical industry. In this Roadmap, we explore how multidisciplinary approaches will enable us to close the carbon cycle and create a circular economy by defossilizing these difficult-to-electrify areas and those that will continue to need carbon. We discuss two approaches for this: developing carbon alternatives and improving our ability to reuse carbon, enabled by separations. Furthermore, we posit that co-design and use-driven fundamental science are essential to reach aggressive greenhouse gas reduction targets.

The relationship between aortic calcification on chest radiograph and neurocognitive impairment after coronary artery bypass grafting.

BACKGROUND: In this study, we aimed to investigate the possible relationship between aortic calcification as detected by preoperative chest radiography and postoperative neurocognitive impairment in patients undergoing coronary artery bypass grafting. METHODS: A total of 124 patients (101 males, 23 females; mean age: 59.9±8.8 years; range, 34 to 84 years) who underwent coronary artery bypass grafting in our clinic between January 2019 and July 2019 were included. Of these patients, 35 whose preoperative chest radiography revealed aortic calcification in the aortic knuckle were included as the patient group. The control group consisted of 89 patients without aortic calcification. The patients with aortic calcification underwent additional imaging with thoracic computed tomography angiography and ascending aorta and aortic arch calcium scores were calculated. Neurocognitive dysfunction was assessed using the Standardized Mini-Mental State Examination. Postoperative delirium was evaluated by confusion assessment method in the intensive care unit. Both groups were compared for demographic, operative and postoperative data. RESULTS: Of all patients included in the study, the overall cerebrovascular event incidence was 3.2%. Although not statistically significant, the number of patients with neurocognitive decline was higher in the patient group than the control group (48.6% vs. 34.8%, respectively; p=0.157). Both Standardized Mini-Mental State Examination score decline and percentage decline were significantly higher in the patients with high aortic arch calcium scores (>2,250 AU). Carotid artery stenosis was 3.2 times higher in the patient group. In the patients with carotid artery stenosis, the aortic arch calcium scores were also higher (p=0.042). CONCLUSION: Aortic calcification detectable on chest radiography with high calcium scores may be associated with neurocognitive impairment and carotid artery stenosis in patients undergoing coronary artery bypass grafting.

Transposition of brachiobasilic arteriovenous fistulas: One-stage or two-stage technique and factors affecting the early maturation.

The brachiobasilic transposition (BBT) arteriovenous fistula (AVF) is a valuable option especially for dialysis patients with previously failed vascular access. We aim to report factors affecting the maturation of BBT-AVF created with either one-stage or two-stage technique. BBT-AVF procedures between January 2015 and May 2019 by a dedicated vascular access team were investigated retrospectively. A total of 122 patients (63 males, 59 females), with 6 to 12 weeks of follow-up after the BBT-AVF procedure were included in the study. Patients of one-stage and two-stage techniques were compared for maturation rates. Patients with successful and failed maturation were compared for baseline characteristics and anatomic factors. Of 122 BBT-AVF procedures, 54 were created with the one-stage and 68 were created with the two-stage technique. The mean age of the patients was 58.2 ± 13.8, the mean brachial artery and basilic vein diameters were 3.91 ± 1.02 mm, and 3.39 ± 1.16 mm. Of 122 included patients, 88 (72.1%) had mature AVFs at follow-up. The AVF maturation rates were similar between the one- and two-stage groups (70.4% vs 73.5%; P = .699). Lower age (62.8 ± 12.5 vs 56.5 ± 13.9; P = .023) and greater brachial artery diameter (3.09 ± 0.84 mm vs 4.23 ± 1.76 mm; P < .048) were the only factors affecting the AVF maturation in univariate analysis. Gender, extremity side, diabetes mellitus, hypertension, and targeted vein diameter were not found to affect the AVF maturation (P = .301, P = .084, P = .134, P = .858, P = .127). Target artery diameter (P = .049) was the only significant factor affecting BBT-AVF maturation in multivariate analysis. One-stage and two-stage BBT-AVFs are similar in terms of maturation rates. Targeted artery diameter was the only factor important in BBT-AVF maturation in our study group. The two-stage technique can be preferred considering smaller incision size and lower complication rate in patients with suitable anatomy.

An Alternative Technique for Ascending and Arcus Aorta Repair in Case of Vascular Diameter Mismatch.

Complicated Type A intramural hematoma involving the arcus aorta requires emergency correction of the aortic arch. Surgical options include reimplantation of the brachiocephalic vessels as an island to a vascular graft, debranching aortic arch surgery, and Kazui technique. This report describes a modified technique for aortic arch repair in a patient with vascular diameter mismatch between the ascending and descending aorta, as well as an intimal tear between the brachiocephalic vessels.

Ultrasonography-guided foam sclerotherapy in patients with small saphenous vein insufficiency.

PURPOSE: Chronic venous insufficiency is an important health problem; small saphenous vein (SSV) insufficiency is one of the leading causes and may affect up to 20% of adults. In addition to conventional treatment methods, endovenous treatment techniques have become popular in treatment of varicose veins. Herein, we report the outcomes of ultrasound-guided foam sclerotherapy (UGFS) in patients with symptomatic SSV insufficiency. METHODS: From January 2014 to June 2018, patients with primary SSV insufficiency treated with UGFS were followed to assess the effectiveness and safety of the procedure. A total of 31 lower limbs of 30 patients (18 females and 12 males), who attended control visits at 1 week, 1, 3, and 6 months, and yearly, after undergoing UGFS, were included in the study. The clinical results, occlusion rates, and the patients' preprocedure and postprocedure Venous Clinical Severity Scores were recorded. RESULTS: The records show that, during the procedure, severe pain occurred at the time of injection in one patient (3%), vasovagal syncope in one patient (3%), hyperpigmentation in five patients (16%), and phlebitis in three patients (9%). It was also recorded that during follow-up 24 legs (78%) showed complete thrombosis and 7 legs (22%) had partial thrombosis. The mean Venous Clinical Severity Score for the patients before UGFS was 8.58 ± 3.78, and 7.25 ± 3.17 after the procedure. No major complications, including sural nerve injury and deep venous thrombosis, were seen during the follow-up period. CONCLUSIONS: The results of this study show that UGFS is a simple, safe, and effective procedure for treatment in patients with symptomatic SSV insufficiency with acceptable side effects.

Transaortic repair of concomitant mitral insufficiency in patients with critical aortic stenosis undergoing aortic valvular replacement.

BACKGROUND: In this study, we present operation technique and outcomes of transaortic mitral valve repair in high-risk patients undergoing aortic valve replacement due to severe aortic stenosis. METHODS: Between January 2005 and March 2016, a total of 11 patients (7 females, 4 males; mean age 71.2±4.1 years; range, 65 to 77 years) with severe aortic valve stenosis (aortic valve area <1 cm2 or aortic valve area index <0.6 cm2/m2) and concomitant moderate or severe mitral regurgitation (non-ischemic, regurgitant jet origin between A2-P2 portions) secondary to left ventricular dysfunction (EuroSCORE logistic score >5%, left ventricular ejection fraction <30%) who were operated were retrospectively analyzed. Aortic valve replacement and transaortic mitral edge-to-edge repair was applied to all patients. Operations were performed through sternotomy, cardiopulmonary bypass, and bicaval venous return. Transesophageal echocardiography was used to evaluate mitral valve before surgery and valve functions after surgery. Postoperative course of all patients was monitored, and postoperative complications were recorded. RESULTS: The mean preoperative ejection fraction was 24.5±4.1% and the mean transaortic pressure gradient was 35.8±4.8 mmHg. The mean aortic cross-clamp time was 62.09±10.1 (range, 43 to 76) min and the median cardiopulmonary bypass time was 90.1±11.9 (range, 66 to 114) min. No hospital mortality was observed. In the postoperative period, two patients experienced renal insufficiency. Hemofiltration was initiated in these patients and no dialysis was required at two weeks. One patient had postoperative atrial fibrillation and one patient had pericardial effusion leading to cardiac tamponade and this patient underwent reoperation. The patients were followed up for a mean of four years and control echocardiography didn"t detect increase in mitral regurgitation degree. CONCLUSION: Transaortic edge-to-edge mitral valve repair can be used in high-risk patients undergoing aortic valve replacement. This technique is feasible with shorter cross-clamp time and can reduce mortality and morbidity in selected high-risk patients.

Highly durable, coking and sulfur tolerant, fuel-flexible protonic ceramic fuel cells.

Protonic ceramic fuel cells, like their higher-temperature solid-oxide fuel cell counterparts, can directly use both hydrogen and hydrocarbon fuels to produce electricity at potentially more than 50 per cent efficiency1,2. Most previous direct-hydrocarbon fuel cell research has focused on solid-oxide fuel cells based on oxygen-ion-conducting electrolytes, but carbon deposition (coking) and sulfur poisoning typically occur when such fuel cells are directly operated on hydrocarbon- and/or sulfur-containing fuels, resulting in severe performance degradation over time3-6. Despite studies suggesting good performance and anti-coking resistance in hydrocarbon-fuelled protonic ceramic fuel cells2,7,8, there have been no systematic studies of long-term durability. Here we present results from long-term testing of protonic ceramic fuel cells using a total of 11 different fuels (hydrogen, methane, domestic natural gas (with and without hydrogen sulfide), propane, n-butane, i-butane, iso-octane, methanol, ethanol and ammonia) at temperatures between 500 and 600 degrees Celsius. Several cells have been tested for over 6,000 hours, and we demonstrate excellent performance and exceptional durability (less than 1.5 per cent degradation per 1,000 hours in most cases) across all fuels without any modifications in the cell composition or architecture. Large fluctuations in temperature are tolerated, and coking is not observed even after thousands of hours of continuous operation. Finally, sulfur, a notorious poison for both low-temperature and high-temperature fuel cells, does not seem to affect the performance of protonic ceramic fuel cells when supplied at levels consistent with commercial fuels. The fuel flexibility and long-term durability demonstrated by the protonic ceramic fuel cell devices highlight the promise of this technology and its potential for commercial application.

Central retinal vein occlusion after coronary artery bypass surgery: A case report.

OBJECTIVE: The aim of this study is to report a case of central retinal vein occlusion (CRVO) after coronary artery bypass graft (CABG) surgery. In this report, we present the third case in the literature with CRVO after cardiopulmonary bypass (CPB), and the first case after CABG. CASE REPORT: A 59-year-old male patient complaining of chest pain was admitted to our hospital. The patient underwent an elective coronary angiography and was diagnosed with three-vessel coronary artery disease. An uneventful coronary artery bypass graft operation was performed using CPB. On the second postoperative day, the patient described blurring and decreased vision in his left eye, whereas the right eye was normal. The anterior-posterior segment was examined by an ophthalmologist who diagnosed central retinal vein occlusion, using a visual acuity test, fundoscopy. After 5 months of treatment, there has been no improvement in the patient's visual acuity. CONCLUSION: As two previous case reports indicated CRVO can be a rare complication after CPB, this study demonstrated that CRVO can also be a complication of CABG. Therefore, CRVO should always be considered as a potential complication after cardiac surgery.