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We report the design and realization of the back focal plane (BFP) imaging for the light emission from a tunnel junction in a low-temperature ultrahigh-vacuum (UHV) scanning tunneling microscope (STM). To achieve the BFP imaging in a UHV environment, a compact "all-in-one" sample holder is designed and fabricated, which allows us to integrate the sample substrate with the photon collection units that include a hemisphere solid immersion lens and an aspherical collecting lens. Such a specially designed holder enables the characterization of light emission both within and beyond the critical angle and also facilitates the optical alignment inside a UHV chamber. To test the performance of the BFP imaging system, we first measure the photoluminescence from dye-doped polystyrene beads on a thin Ag film. A double-ring pattern is observed in the BFP image, arising from two kinds of emission channels: strong surface plasmon coupled emissions around the surface plasmon resonance angle and weak transmitted fluorescence maximized at the critical angle, respectively. Such an observation also helps to determine the emission angle for each image pixel in the BFP image and, more importantly, proves the feasibility of our BFP imaging system. Furthermore, as a proof-of-principle experiment, electrically driven plasmon emissions are used to demonstrate the capability of the constructed BFP imaging system for STM induced electroluminescence measurements. A single-ring pattern is obtained in the BFP image, which reveals the generation and detection of the leakage radiation from the surface plasmon propagating on the Ag surface. Further analyses of the BFP image provide valuable information on the emission angle of the leakage radiation, the orientation of the radiating dipole, and the plasmon wavevector. The UHV–BFP imaging technique demonstrated here opens new routes for future studies on the angular distributed emission and dipole orientation of individual quantum emitters in UHV. [ABSTRACT FROM AUTHOR]

Background: Thromboembolic complications after stenting of intracranial aneurysms may be affected by antiplatelet administration. Aims: This retrospective study aimed to assess the safety of intravenous tirofiban versus loading dose of oral clopidogrel for preventing thromboembolism in stent-assisted coiling of intracranial aneurysms. Methods: From January 2006 to December 2013, 281 patients with cerebral aneurysms were treated with stent-coiling using two antiplatelet strategies in comparison: the initial strategy (a loading dose of ≥300 mg clopidogrel followed by dual antiplatelet, clopidogrel group) and the modified strategy (intravenous administration of tirofiban 8 μg/kg over 3 min followed by a maintenance dose of 0.1 μg/kg/min for 24 h, tirofiban group). The end points were rates of perioperative thromboembolic events and intracranial hemorrhages. Results: Thromboembolic events were observed more often in the clopidogrel group (13/120 aneurysms, 10.83%) than the tirofiban group (6/178 aneurysms, 3.37%; P=0.010), with no increase in the rate of intracranial hemorrhages (P=0.164). In the ruptured subgroups, thromboembolic events were significantly fewer in the tirofiban subgroup (5/128, 3.91%) compared with the clopidogrel subgroup (7/53, 13.21%; P=0.043) with no increase in the rate of hemorrhage (P=0.360). Conclusions: Intravenous administration of tirofiban is safe in intracranial aneurysms treated with stent-assisted coiling. [ABSTRACT FROM AUTHOR]

Objective To evaluate the safety and efficiency of mechanical thrombectomy with Solitaire AB stent in the treatment of acute ischemic stroke caused by large artery occlusion of anterior circulation. Methods Clinical data of 31 patients with acute ischemic stroke caused by large artery occlusion of anterior circulation, who underwent mechanical thrombectomy with Solitaire AB stent, were reviewed retrospectively. Recanalization results were assessed by immediate scale of thrombolysis in cerebral infarction (TICI) after thrombectomy. National Institutes of Health Stroke Scale (NIHSS) was used to evaluate neurological function at one week after operation, and modified Rankin Scale (mRS) was used to evaluate outcomes at 3 months after operation. Complications related to the procedure, such as perioperative embolic events, intracranial hemorrhage or death within 3 months after operation, were recorded. Results A total of 33 Solitaire AB stents were used in 31 patients. The initial success rate of recanalization was 61.29% (19/31). Among the other 12 patients, one patient with TICI Grade 2a and favorable distal blood supply was not further freated, while 11 patients underwent stent implantation as a rescue treatment and 9 of them were successful. The final recanalization rate was 90.32% (28/31). The NIHSS score one week after operation was 8.81 ± 3.40, which was significantly lower than the score 16.06 ± 4.82 on admission (t = -7.104, P = 0.000). Three months after operation, there were 16 patients (51.61%) with good prognosis (mRS score ≤ 2). Perioperative embolization occurred in 3 patients. Intracranial hemorrhage occurred in 4 patients during the 3-month follow-up period, and 6 patients were dead. Conclusions The application of Solitaire AB stent in mechanical thrombectomy for treating acute ischemic stroke is efficient and safe. Stent implantation can be used as adjunctive treatment when initial recanalization with Solitaire AB stent is failed. [ABSTRACT FROM AUTHOR]

Purpose: We aimed to investigate the safety and effectiveness of intracranial stenting in a population with severe (≥ 70%) symptomatic intracranial internal carotid artery (ICA) atherosclerotic stenosis.Methods: Fifty-eight patients with severe intracranial ICA atherosclerotic stenosis were prospectively enrolled. The baseline data, cerebral angiography, success rate, perioperative complications, clinical and imaging follow-up were prospectively analyzed.Results: All patients had successful intracranial stenting (100%), and the mean degree of stenosis was improved from 84.3% ± 7.5% to 23.5% ± 5.1% after the stent procedure. During the 30-day perioperative period, only one patient (1.7%) had ischemic stroke. Seven patients (12.1%) had headache and dysphoria. Thirty-six patients (62.1%) had clinical follow-up for 6-68 months after stenting. Five female patients (13.9%) had ipsilateral stroke including one death, but no disabling stroke, while three other patients (8.3%) had ipsilateral temporary ischemic attack (TIA). The recurrent stroke rate was higher in patients presenting with stroke (4/17, 23.5%) than in patients presenting with TIA (1/19, 5.3%), with no statistical significance (P = 0.33). Thirteen patients (22.4%) had imaging follow-up of 5-12 months following stenting, five of whom (38.5%) had in-stent restenosis.Conclusion: Intracranial stenting for patients with intracranial ICA atherosclerotic stenosis has a low perioperative stroke rate and decent outcome on long-term follow-up, despite a relatively high in-stent restenosis rate. [ABSTRACT FROM AUTHOR]