Coherent electronic and nuclear dynamics in a rhodamine heterodimer-DNA supramolecular complex

Elucidating the role of quantum coherences in energy migration within biological and artificial multichromophoric antenna systems is the subject of an intense debate. It is also a practical matter because of the decisive implications for understanding the biological processes and engineering artificial materials for solar energy harvesting. A supramolecular rhodamine heterodimer on a DNA scaffold was suitably engineered to mimic the basic donor-acceptor unit of light-harvesting antennas. Ultrafast 2D electronic spectroscopic measurements allowed identifying clear features attributable to a coherent superposition of dimer electronic and vibrational states contributing to the coherent electronic charge beating between the donor and the acceptor. The frequency of electronic charge beating is found to be 970 cm-1 (34 fs) and can be observed for 150 fs. Through the support of high level ab initio TD-DFT computations of the entire dimer, we established that the vibrational modes preferentially optically accessed do not drive subsequent coupling between the electronic states on the 600 fs of the experiment. It was thereby possible to characterize the time scales of the early time femtosecond dynamics of the electronic coherence built by the optical excitation in a large rigid supramolecular system at a room temperature in solution. © 2017 the Owner Societies.Multi valued and parallel molecular logi

Second asymptomatic carotid surgery trial (ACST-2): a randomised comparison of carotid artery stenting versus carotid endarterectomy

Background: Among asymptomatic patients with severe carotid artery stenosis but no recent stroke or transient cerebral ischaemia, either carotid artery stenting (CAS) or carotid endarterectomy (CEA) can restore patency and reduce long-term stroke risks. However, from recent national registry data, each option causes about 1% procedural risk of disabling stroke or death. Comparison of their long-term protective effects requires large-scale randomised evidence. Methods: ACST-2 is an international multicentre randomised trial of CAS versus CEA among asymptomatic patients with severe stenosis thought to require intervention, interpreted with all other relevant trials. Patients were eligible if they had severe unilateral or bilateral carotid artery stenosis and both doctor and patient agreed that a carotid procedure should be undertaken, but they were substantially uncertain which one to choose. Patients were randomly allocated to CAS or CEA and followed up at 1 month and then annually, for a mean 5 years. Procedural events were those within 30 days of the intervention. Intention-to-treat analyses are provided. Analyses including procedural hazards use tabular methods. Analyses and meta-analyses of non-procedural strokes use Kaplan-Meier and log-rank methods. The trial is registered with the ISRCTN registry, ISRCTN21144362. Findings: Between Jan 15, 2008, and Dec 31, 2020, 3625 patients in 130 centres were randomly allocated, 1811 to CAS and 1814 to CEA, with good compliance, good medical therapy and a mean 5 years of follow-up. Overall, 1% had disabling stroke or death procedurally (15 allocated to CAS and 18 to CEA) and 2% had non-disabling procedural stroke (48 allocated to CAS and 29 to CEA). Kaplan-Meier estimates of 5-year non-procedural stroke were 2·5% in each group for fatal or disabling stroke, and 5·3% with CAS versus 4·5% with CEA for any stroke (rate ratio [RR] 1·16, 95% CI 0·86–1·57; p=0·33). Combining RRs for any non-procedural stroke in all CAS versus CEA trials, the RR was similar in symptomatic and asymptomatic patients (overall RR 1·11, 95% CI 0·91–1·32; p=0·21). Interpretation: Serious complications are similarly uncommon after competent CAS and CEA, and the long-term effects of these two carotid artery procedures on fatal or disabling stroke are comparable. Funding: UK Medical Research Council and Health Technology Assessment Programme

Peripheral Stepwise Degradation Of A Porphyrin J-Aggregate

For metalation of the acidic form of tetrakis(4-sulfonatophenyl)porphyrin (dianionic H₄TPPS₄) by Cu(II), the order of reagent mixing determines the rate and mechanism of CuTPPS₄ formation. When copper salts are added last, the kinetic profile is fit as a (pseudo)-first-order process. However, J-aggregates of the H₄TPPS₄ porphyrin are rapidly formed at pH similar to 3 when Cu(II) salts are incorporated in solution prior to porphyrin addition. The subsequent porphyrin units metalation leads to the disassembling of these arrays via a pseudo-zero-order kinetic profile, suggesting an attack of the metal ion at the rims of the nanostructure

Aggregates Of A Cationic Porphyrin As Supramolecular Probes For Biopolymers

The copper(II) derivative of the dicationic trans-bis(N-methylpyridinium-4-yl)diphenylporphyrin (t-CuPagg) forms large fractal aggregates in aqueous solution under moderate ionic strength conditions. A kinetic investigation of the aggregation process allows for a choice of experimental conditions to quickly obtain stable assemblies in solution. These positively charged aggregates are able to interact efficiently with negatively charged chiral species, (including bacterial spores) leading to induced circular dichroism signals in the Soret region of the porphyrin, now acting as a sensitive chiroptical probe. (C) 2015 Elsevier Inc. All rights reserved

Supramolecular Chirality Transfer To Large Random Aggregates Of Porphyrins

Chirality is rapidly induced in a fractal aggregate of the porphyrin t-CuPagg by addition of alpha-helical poly-glutamate. These results demonstrate a facile transfer of chirality via noncovalent interactions to preformed supramolecular assemblies grown in the absence of a chiral template

Trattamento endovascolare delle lesioni steno-ostruttive dell'asse arterioso iliaco in 312 pazienti = Endovascular treatment of steno-obstructive lesions of iliac arteries in 312 patients

Background. This retrospective study examines the long-term results of percutaneous transluminal angioplasty (PTA) in the treatment of steno-obstructive lesions of iliac arteries. It also compares the results of simple PTA versus PTA with stenting at 24 months. Methods. Between June 1997 and July 2001, 312 iliac PTA (249 males and 63 females) with and without stenting were performed at our Institute. We studied short-term and long-term patency after a mean follow-up of 24 months, taking into account clinical results, objective examination, duplex ultra-sonography at 2, 6, 12 months and annually, and arteriography in doubtful cases or with complications. Results. There was no significant difference in short-term patency between the 2 types of procedures. After a follow-up of 24 months (3-48 months) the cumulative rate of patency for simple PTA was 58.23%, while it was 78.54% for PTA with stenting, whether or not associated with surgery (intraoperative transluminal angioplasty or ITA). Conclusions. Data obtained from our series concord with those reported in international literature, which underlines that PTA with stenting is a safer procedure than simple PTA ensuring long-term patency in the treatment of iliac district lesions, especially of the common iliac artery. PTA with stenting can also be used with multiple, long and complex lesions that simple PTA cannot resolve

Treatment options for visceral artery aneurysms : ten year experience

Aim: Open surgical repair (OSR) and endovascular techniques (ET) are both described in the literature for treating visceral artery aneurysms (VAAs). Aim of this study is to report a two-center experience of patients treated for a VAA using either OSR or ET, analyzing perioperative outcomes. Methods: Clinical data of 32 VAAs in 32 patients treated between January 2001 and May 2011 were retrospectively reviewed and outcomes analyzed. Results: Eighteen patients were men (56.3%). Median age was 64 years (range 26-79). Sixteen aneurysms were symptomatic: half of them were ruptured causing hemoperitoneum or gastrointestinal bleeding. ET were employed in 19 cases (59%) using covered stents (7 patients), coil embolization (5), plug placement (1), thrombin injection (2) and multiple associated techniques (4). OSR consisted in aneurysmectomy with end to end anastomoses (5 patients) or interposition graft (1), aneurysm ligation (4), splenectomy (2). One patient died during open surgery for hemoperitoneum due to VAA rupture (3%). OSR and ET had similar perioperative complication rates (5.2% vs. 15.3%, P=0.76). OSR had a longer in-hospital stay than ET (8 vs. 4 days, P=0.04). The presence of pancreatitis and alcohol abuse were more frequent in patients who presented with VAAs rupture. Clinical presentation with hemoperitoneum or aneurysm rupture were associated with higher mortality, regardless of the type of treatment. Conclusion: Both OSR and ET offered a safe way to treat VAAs in our experience

Controlling J-Aggregates Formation And Chirality Induction Through Demetallation Of A Zinc(II) Water Soluble Porphyrin

Under acidic conditions and at high ionic strength, the zinc cation is removed from its metal complex with 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS₄) thus leading to the diacid free porphyrin, that subsequently self-organize into J-aggregates. The kinetics of the demetallation step and the successive supramolecular assembly formation have been investigated as a function of pH and ionic strength (controlled by adding ZnSO₄). The demetallation kinetics obey to a rate law that is first order in [ZnTPPS₄] and second order in [H⁺], according to literature, with k₂ = 5.5 ± 0.4 M⁻² s⁻¹ at 298 K (IS = 0.6 M, ZnSO₄). The aggregation process has been modeled according to an autocatalytic growth, where after the formation of a starting seed containing m porphyrin units, the rate evolves as a power of time. A complete analysis of the extinction time traces at various wavelengths allows extraction of the relevant kinetic parameters, showing that a trimer or tetramer should be involved in the rate-determining step of the aggregation. The extinction spectra of the J-aggregates evidence quite broad bands, suggesting an electronic coupling mechanism different to the usual Frenkel exciton coupling. Resonance light scattering intensity in the aggregated samples increases with increasing both [H⁺] and [ZnSO₄]. Symmetry breaking occurs in these samples and the J-aggregates show circular dichroism spectra with unusual bands. The asymmetry g-factor decreases in its absolute value with increasing the catalytic rate kc, nulling and eventually switching the Cotton effect from negative to positive. Some inferences on the role exerted by zinc cations on the kinetics and structural features of these nanostructures have been discussed

Treatment options for visceral artery aneurysms: ten years\u2019 experience

Open surgical repair (OSR) and endovascular techniques (ET) are both described in the literature for treating visceral artery aneurysms (VAAs). Aim of this work is to report a two-center experience (Division of Vascular Surgery, San Carlo Borromeo Hospital, Milan, and Ist Unit of Vascular Surgery, IRCCS Policlinico San Donato, San Donato Milanese) of patients treated for a VAA using either OSR or ET, analyzing perioperative outcomes. Method Clinical data of 32 VAAs in 32 patients treated between January 2001 and May 2011 were retrospectively reviewed. Outcomes were analyzed using log-rank test, chi2 and Wilcoxon. Eighteen patients were men (56,3%). Median age was 64 years (range 26-79). Median sac diameter was 2,7 cm (range 1,6-9 cm). Sixteen aneurysms were asymptomatic, while another 16 were symptomatic: half of them were ruptured causing hemoperitoneum or gastrointestinal bleeding. The artery involved was the splenic artery in fifteen cases (46,9%), in 7 the hepatic (21,8%), in 2 the gastroepiploic and the superior mesenteric artery (both 6,3%), in 5 gastroduodenal or pancreaticoduodenal artery (15,6%) and in 1 the celiac trunk (3,1%). Two patients with hepatic aneurysms were affected by Ehlers-Danlos Syndrome and polyarteritis nodosa; an alpha-1 antitrypsin deficiency was found in a patient with a gastroduodenal aneurysm. Results ET was performed in 19 cases (59%) using covered stents (7 patients), coil embolization (5), plug placement (1), thrombin injection (2) and multiple associated techniques (4). OSR consisted in aneurysmectomy with end to end anastomoses (5 patients) or interposition graft (1), aneurysm ligation (4), splenectomy (2). One patient died during exploration for hemoperitoneum due to VAA rupture (3%). After ET, 3 patients experienced respectively a temporary increase of pancreatic amylase and serum creatinine and one splenic infarction (covered stent placed for splenic artery aneurysm). Among OSR one patient experienced a transient raising of pancreatic amylase; a pancreatic abscess after a splenic aneurysm ligation (which led to death in POD 72) was found in one; a third patient had a pancreatic fistula after right gastroepiploic aneurysm resection. OSR and ET had similar perioperative complication rates (38,4% vs 26,3%, p=0.54). OSR had a longer inhospital stay than ET(8 vs 4 days, p=0,07). Conclusions Clinical presentation, location of the aneurysm, as well as patients' operative risk are the factors that mainly influence surgical strategy. Both OSR and ET offered a safe way to treat VAAs in our experience. ET was associated with shorter in-hospital stay compared to OSR

The role of counter-anions in the kinetics and chirality of porphyrin J-aggregates

Kinetics of the growth of TPPS4 porphyrin J-aggregates slow down in the order H2SO4 > HCl > HBr > HNO3 > HClO4, in agreement with the Hofmeister series. The rate constants and the extent of chirality correlate with the structure-making or breaking abilities of the different anions with respect to the hydrogen bonding network of the solvent