Collective Strong Coupling Modifies Aggregation and Solvation.

Intermolecular (Coulombic) interactions are pivotal for aggregation, solvation, and crystallization. We demonstrate that the collective strong coupling of several molecules to a single optical mode results in notable changes in the molecular excitations around a single perturbed molecule, thus representing an impurity in an otherwise ordered system. A competition between short-range coulombic and long-range photonic correlations inverts the local transition density in a polaritonic state, suggesting notable changes in the polarizability of the solvation shell. Our results provide an alternative perspective on recent work in polaritonic chemistry and pave the way for the rigorous treatment of cooperative effects in aggregation, solvation, and crystallization.

Do We Really Need Quantum Mechanics to Describe Plasmonic Properties of Metal Nanostructures?

Optical properties of metal nanostructures are the basis of several scientific and technological applications. When the nanostructure characteristic size is of the order of few nm or less, it is generally accepted that only a description that explicitly describes electrons by quantum mechanics can reproduce faithfully its optical response. For example, the plasmon resonance shift upon shrinking the nanostructure size (red-shift for simple metals, blue-shift for d-metals such as gold and silver) is universally accepted to originate from the quantum nature of the system. Here we show instead that an atomistic approach based on classical physics, ωFQFµ (frequency dependent fluctuating charges and fluctuating dipoles), is able to reproduce all the typical "quantum" size effects, such as the sign and the magnitude of the plasmon shift, the progressive loss of the plasmon resonance for gold, the atomistically detailed features in the induced electron density, and the non local effects in the nanoparticle response. To support our findings, we compare the ωFQFµ results for Ag and Au with literature time-dependent DFT simulations, showing the capability of fully classical physics to reproduce these TDDFT results. Only electron tunneling between nanostructures emerges as a genuine quantum mechanical effect, that we had to include in the model by an ad hoc term.

Embo-EVAR: A Technique to Prevent Type II Endoleak? A Single-Center Experience.

BACKGROUND: Intraprocedural aneurysm sac embolization (embo-EVAR) during endovascular abdominal aneurysm repair (EVAR) using coils and fibrin glue is a technique for preventing type II endoleak (EII). Our aim is to evaluate feasibility, safety and clinical outcome of this promising approach. MATERIALS AND METHODS: A retrospective clinical case analysis of 72 patients who underwent EVAR during the period 2011-2014. Two groups were compared at 6 and 12 months follow-up with contrast media computed tomography scan and contrast-enhanced ultrasound (CEUS) imaging: consecutively, 36 patients (group A) treated with classic EVAR and 36 patients (group B) treated with embo-EVAR. Coils were released filling better as possible the aneurysm sac; the embolization was completed by injecting fibrin glue. Device and materials used, differential systemic and sac pressures, presence of any endoleak, and complication were registered. RESULTS: In our experience, we had 100% technical success without surgical conversion. Embo-EVAR was performed, after endograft deployment, in group B patients, all with ratio of Δ-pressures (obtained from Δ-sac pressure/Δ-differential pressure) > 0.16. No early or late complications occurred and mortality was nil. Follow-up was performed with computed tomography-angiography and CEUS at 6 and 12 months. We observed 9 type II and 1 type Ia endoleak in group A and 2 type II and 1 type Ib endoleaks in group B. Mean radiation exposure time was 30.3 min in group A and 43.3 min in group B. EVAR procedure average cost was 9,000 €. The average cost of sac embolization was 1,500€. CONCLUSIONS: Although a randomized study is necessary, embo-EVAR may be a valid approach to prevent type II endoleaks and further complications. Mild costs and exposure-dose increase could be accepted to avoid reinterventions, and in our experience, it could be routinely performed with excellent results.

Treatment of juxtarenal aortic aneurysm with the Multilayer stent.

PURPOSE: To report the use of a new type of uncovered stent to treat aortic aneurysms. CASE REPORT: Under compassionate use, an 81-year-old man with multiple comorbidities and an expanding 63-mm juxtarenal abdominal aortic aneurysm was treated with a 28×100-mm Multilayer flow-modulating stent. Immediately, the blood flow velocity inside the aneurysm sac appeared reduced on fluoroscopy. All aortic branches covered by the stent (celiac trunk, superior mesenteric artery, and renal arteries) remained patent. Serial computed tomography at up to 12 months has shown excellent stent and visceral artery patency and progressive reduction in the sac diameter (58 mm) and volume (84.9 cm(3) to 82.8 cm(3)). CONCLUSION: This case shows that the use of an uncovered multilayer stent reduces the flow in the aneurysm but preserves perfusion of the branch arteries, which is impossible with covered stents.