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The present work provides an analysis of the potential impact of fossil-based Low Carbon Aviation Fuels (LCAF) for the European aviation sector, with a time horizon to 2050. LCAF are a crude-derived alternative to kerosene, offering some Green House Gas (GHG) savings, and have been defined by ICAO as eligible fuels for mitigating the environmental impact of aviation. A methodological framework to evaluate the EU technical potential for LCAF production is developed, based on data on crude utilization for jet fuel production in EU refineries, relevant carbon intensity reduction technologies, market prices, and aviation fuel volumes. Two different baselines for fossil-derived kerosene carbon intensity (CI) are considered: a global figure of 89 gCO2e/MJ and an EU-27-specific one of 93.1 gCO2eq/MJ. Three scenarios considering increasing levels of CI reduction are then defined, taking into account the current and potential commercial availability of some of the most relevant carbon intensity reduction technologies. The analysis demonstrates that, even if LCAF could offer GHG saving opportunities, their possible impact, especially when compared to the ambition level set in the most recent European legislative proposals, is very limited in most of the analysed scenarios, with the exception of the most ambitious ones. At 2030, a non-zero technical potential is projected only in the higher CI reduction scenario, ranging between 1.8% and 14.2% of LCAF market share in the EU-27 (equal to 0.6 to 4.75 Mtoe), depending on the considered Baseline for CI. At 2050, almost all considered scenarios project a larger technical potential, ranging between 6.9% and 22.2% for the global Baseline (2.21 to 7.13 Mtoe), and between 1.8% and 16.2% for the EU-27 Baseline (0.58 to 5.2 Mtoe). LCAF additional costs to current production costs are also discussed, given their relevance in large-scale deployment of these technologies, and are projected to range between 39 and 46.8 USD/toe.

The present work investigates the effect of fuel injection timing on combustion stratification and soot formation in an optically accessible, single cylinder light duty diesel engine. The engine operated under low load and low engine speed conditions, employing a single injection scheme. The conducted experiments considered three different injection timings, which promoted Partially Premixed Combustion (PPC) operation. The fuel quantity of the main injection was adjusted to maintain the same Indicated Mean Effective Pressure (IMEP) value among all cases considered. Findings were analysed via means of pressure trace and apparent heat transfer rate (AHTR) analyses, as well as a series of optical diagnostics techniques, namely flame natural luminosity, CH* and C2* chemiluminescence high-speed imaging, as well as planar Laser Induced Incandescence (pLII). For the chemiluminescence high-speed imaging a novel methodology was developed to acquire the net spatially resolved chemiluminescence signal, using combustion spectroscopy to remove the background chemiluminescence and thermal radiation signal. The analysis suggests that when the injection timing advanced, the stratification of the combustion became weaker, as indicated by the natural luminosity signal, due to the better pre-mixing between the injected fuel and the surrounding air. The enhanced premixing resulted in lower levels of in-cylinder soot late in the combustion cycle and, presumably the lowest engine-out soot emissions, because of the limited formation of locally fuel-rich areas inside the cylinder. This came at the price of increased fuel consumption.

This work employs a combination of pressure trace analysis, high-speed optical measurements and laser-based techniques for the assessment of the effects of various post-injection schemes on the soot reduction potential in an optical single-cylinder light-duty diesel engine. The engine was operated under a multiple injection scheme of two pilot and one main injection, typical of a partially premixed combustion mode, at the lower end of the load and engine speed range (ca 2.0 bar IMEP at 1200 r/min). Experiments considering the influence of the post-injection fuel amount (up to 15% of the total fuel quantity per cycle) and the post-injection timing within the expansion stroke (5, 10 and 15 CAD aTDC), under a constant total fuel mass per cycle, have been conducted. Findings were analysed via means of pressure trace and apparent rate of heat transfer analyses, as well as a series of optical diagnostic techniques, namely, high-speed flame natural luminosity imaging, CH*, C∗2 and OH* line-of-sight chemiluminescence, as well as planar laser-induced incandescence measurements at 31 and 50 CAD aTDC. The combination of post-injection fuel amount and timing has substantial effects on charge reactivity and soot oxidation potential. The analysis reveals that an amount of fuel (7% of the total fuel mass per cycle) injected more than 10 CAD after the main combustion event leads to higher levels of soot emissions, while a larger amount of fuel (15% of the total fuel mass) injected 5 CAD after the main combustion event appears to have a beneficial effect on the soot oxidation processes. Overall, results indicate that a post-injection scheme close to the main combustion phasing could reduce soot levels and improve engine performance, that is, higher IMEP levels at the same fuel consumption rates, although it could increase engine noise.

Complex iliac anatomy including extreme tortuosity constitutes a relative contraindication for endovascular abdominal aortic aneurysm repair with additional risk of limb-graft occlusion. The Gore Excluder limb-graft is a flexible stent-graft, which adapts easily to iliac tortuosity. Nevertheless, the presence of the stiff guide wire does not always allow for an ideal apposition of the stent graft to the angulated common iliac artery vessel wall. We describe herein a modified technique for Gore Excluder limb-graft deployment with partial removal of the stiff wire in cases with difficult tortuous or narrow iliac arteries during endovascular abdominal aortic aneurysm repair.

Background Isolated acute abdominal aortic dissection (IAAAD) is considered an unusual clinical entity and is traditionally treated by open surgical repair. We report our single-center experience during the last 9 years, evaluating the outcomes after endovascular repair in this patient population. Methods All patients with a diagnosis of IAAAD treated in our institute were included in this retrospective review. Between January 2004 and December 2012, 38 patients suffering from an acute aortic dissection were referred regionally for intervention to our department: 24 (63.2%) with a thoracic aortic dissection type B and 14 patients (36.8%, all male; median age, 65 years) with an IAAAD. Demographics, perioperative, procedure-specific, and follow-up data were prospectively aggregated in an electronic database. Results Patients suffering from IAAAD presented with acute abdominal pain (n = 13) and acute lumbar pain (n = 1). Insufferable pain and enlargement of the aorta were the main indications for treatment. Mean (± standard deviation) maximal abdominal aortic diameter at presentation was 3.5 ± 0.94 cm (range, 2.6-5.1 cm). None of these patients had a concomitant thoracic aortic dissection. All patients were treated by endovascular means, with a primary technical success rate of 100%. Two patients (14%) died perioperatively from cardiac causes. Median hospital stay was 4.5 days (range, 3-16 days). During a mean follow-up period of 37.41 ± 23.56 months (range, 8-82 months; median, 32.5 months), two patients experienced primary treatment failure needing reintervention that led to a successful outcome. The cumulative free-from-reintervention rate was estimated 90.9% at 58 months (standard error, 8.7%). A full aortic remodeling without any events was noted in all other patients during the follow-up period. Conclusions Based on our series, IAAAD may represent a not so rare clinical entity as generally thought, suggesting that it may be underdiagnosed. Endovascular treatment of IAAAD appears to be a feasible and efficient therapeutic approach and might be considered as the first-line treatment in all patients with suitable anatomy.

Non-intrusive chemiluminescence measurements have been used as heat release rate and equivalence ratio indicators for gas turbine combustor active control. In the present study, measurements and modelling of OH*, CH(A)*, C 2 *, and CO 2 * chemiluminescence are used to examine chemiluminescence sensing of heat release rate and equivalence ratio in premixed counterflow methane – air flames with equivalence ratio from 0.6 to 1.3 and strain rate from 80 to 400 s -1 . Two spectrally resolved detecting optical systems were used to detect spatially-averaged (global) and spatially resolved (local) chemiluminescence characteristics in the reaction zone. A recently published reaction mechanism 1 for the chemiluminescence of the OH*, CH*, and C 2 * species is incorporated to GRI-Mech 3.0. The augmented mechanism is further validated against the experimental results of the present study and is used to predict the chemiluminescence characteristics of premixed counterflow methane – air flames. The mechanism includes OH* chemiluminescence formation paths from hydrogen reaction, which have not been evaluated before in premixed counterflow flames. The CHEMKIN based counterflow flame code, OPPDIF is employed to simulate the experiments. The calculated OH* and CH(A)* chemiluminescence agrees well with the experimental results measured by both optical methods. Both the experimental and numerical results demonstrate the ability of OH* and CH(A)* intensities to mark heat release rate in methane – air flames. Overall, CH* may be preferable for heat release rate sensing applications at elevated equivalence ratio and strain rate. For equivalence ratio sensing in methane combustion, the measured and simulated OH*/CH(A)* chemiluminescent intensity ratio is highly dependent on equivalence ratio and nearly independent of strain rate. Thus, this ratio can be used to monitor equivalence ratio. However, a non-monotonic behavior of the OH*/CH* ratio for very lean combustion (ER < 0.7) is observed, in agreement with previous studies. This behavior can be reproduced by the reaction mechanisms. The behavior of OH*/CH(A)* chemiluminescent intensity ratio for flames of methanepropane blends are also calculated with the detailed chemistry model. The addition of propane in methane modifies the behaviour of OH*/CH(A)* chemiluminescent intensity ratio dramatically. However, the numerical results suggest that the OH*/CH(A)* chemiluminescent intensity ratio is an indicator of equivalence ratio in lean methanepropane fuel blended flames.

A 58-year-old woman presented with gangrene of the left upper arm stump caused by an arteriovenous malformation originating from the subclavian artery. She had been treated unsuccessfully in the past with repeated attempts of coil embolization and débridement, but finally she underwent arm amputation. A 14 mm diameter occlusion self-expandable stent was placed in the left subclavian artery via ipsilateral brachial artery access, with immediate and complete interruption of arterial supply to the vascular malformation. This minimally invasive treatment provides an alternative method of management of arteriovenous malformations in the subclavian region.

Background Infected femoral artery pseudoaneurysm (IFAP) is a severe complication in parenteral drug abusers, with difficult and controversial management. Ligation alone without revascularization is frequently associated with later intermittent claudication and limb amputation. Furthermore, arterial reconstruction with a synthetic or venous conduit is limited because of a contaminated field and, often, unavailability of autologous venous grafts. In this study, we present our experience with the internal iliac artery (IIA) as a graft for arterial reconstruction after IFAP excision in these patients. Methods Data of 14 consecutive patients who presented with IFAP secondary to parenteral drug abuse from 2001 to 2005 were analyzed. Twelve patients (85.7%) were male. The median age was 27 years (range, 19-42 years). In 13 cases, the IFAP involved the common femoral artery, and in 1 case it involved the profunda femoris artery (PFA). In nine patients, we used the IIA for arterial reconstruction (five as a patch and four as an interposition graft), whereas in two patients the arterial deficit was repaired with a great saphenous vein patch. In two cases, an extra-anatomic bypass with a synthetic polytetrafluoroethylene graft was performed. In one patient, the pseudoaneurysm involved the PFA and was treated with excision and ligation of the PFA. Results All nine patients who underwent revascularization with the use of IIA were free of claudication symptoms. None of them experienced any perioperative complications, had signs of reinfection, or required limb amputation during the follow-up period (median, 19 months; range, 4-52 months). Regarding the remaining five patients, one died 25 days after surgery because of multiorgan failure, and one underwent reoperation because of proximal anastomotic rupture of a synthetic graft. The latter patient finally underwent a transmetatarsal amputation. Conclusions The use of IIA for arterial reconstruction after IFAP excision in drug abusers is safe and effective. These preliminary results indicate that the implementation of this technique offers many advantages compared with traditional treatment options.