The Design of the Emission Layer for Electron Multipliers.

The electron multipliers gain is closely related to the secondary electron emission coefficient (SEE) of the emission layer materials. The SEE is closely related to the thickness of the emission layer. If the emission layer is thin, the low SEE causes the low gain of electron multipliers. If the emission layer is thick, the conductive layer can't timely supplement charge to the emission layer, the electronic amplifier gain is low too. The electron multipliers usually choose Al2O3 and MgO film as the emission layer because of the high SEE level. MgO easy deliquescence into Mg(OH)2 Mg2(OH)2CO3 and MgCO3 resulting in the lower SEE level. The SEE level of Al2O3 is lower than MgO, but Al2O3 is stable. We designed a spherical system for testing the SEE level of materials, and proposed to use low-energy secondary electrons instead of low-energy electron beam for neutralization to measuring the SEE level of Al2O3, MgO, MgO/Al2O3, Al2O3/MgO, and precisely control the film thickness by using atomic layer deposition. We propose to compare the SEE under the adjacent incident electrons energy to partition the SEE value of the material, and obtain four empirical formulas for the relationship between SEE and thickness. Since the main materials that cause the decrease in SEE are Mg2(OH)2CO3 and MgCO3, we use the C element atomic concentration measured by XPS to study the deliquescent depth of the material. We propose to use the concept of transition layer for SEE interpretation of multilayer materials. Through experiments and calculations, we put forward a new emission layer for electron multipliers, including 2-3 nm Al2O3 buffer layer, 5-9 nm MgO main-body layer, 1 nm Al2O3 protective layer or 0.3 nm Al2O3 enhancement layer. We prepared this emission layer to microchannel plate (MCP), which significantly improved the gain of MCP. We can also apply this new emission layer to channel electron multiplier and separate electron multiplier.

The Design of the AZO Conductive Layer on Microchannel Plate.

When the resistivity of the AZO conductive layer is within the MCP resistance requirement, the interval of the Zn content is very narrow (70-73%) and difficult to control. Aiming at the characteristics of the AZO conductive layer on the microchannel plate, an algorithm is designed to adjust the ratio of the conductive material ZnO and the high resistance material Al2O3. We put forward the concept of the working resistance of the MCP (i.e., the resistance during the electron avalanche in the microchannel). The working resistance of AZO-ALD-MCP (Al2O3/ZnO atomic layer deposition microchannel plate) was measured for the first time by the MCP resistance test system. In comparison with the conventional MCP, we found that the resistance of AZO-ALD-MCP in working state and non-working state is very different, and as the voltage increases, the working resistance significantly decreases. Therefore, we proposed a set of analytical methods for the conductive layer. We also proposed to adjust the ratio of the conductive material of the ALD-MCP conductive layer to the high-resistance material under the working resistance condition, and successfully prepared high-gain AZO-ALD-MCP. This design opens the way for finding better materials for the conductive layer of ALD-MCP to improve the performance of MCP.

Role of contrast-enhanced magnetic resonance high-resolution variable flip angle turbo-spin-echo (T1 SPACE) technique in diagnosis of transverse sinus stenosis.

PURPOSE: Transverse sinus stenosis (TSS) is the most sensitive imaging characteristic of idiopathic intracranial hypertension (IIH). This study aimed to assess the diagnostic performance of contrast-enhanced magnetic resonance high-resolution variable flip angle turbo-spin-echo (T1 SPACE) technique in TSS patients and evaluate the diagnostic accuracy of enhanced T1 SPACE, and phase-contrast magnetic resonance venography (PC MRV) with digital subtraction angiography (DSA) as standard imaging. METHOD: This prospective study enrolled 62 patients with suspected IIH and PC MRV-confirmed transverse sinus stenosis. All patients underwent lumbar puncture, PC MRV, enhanced T1 SPACE sequences and DSA examination. The accuracy, sensitivity, and specificity of enhanced T1 SPACE in detecting venous sinus stenosis were calculated and compared with those of PC MRV. Intermodality agreement (Kendall's rank correlation coefficients and weighted kappa statistic) was assessed. RESULTS: Sixty-two patients were enrolled from November 2016 to October 2018. For the measured stenosis, better correlation was observed in enhanced T1 SPACE and DSA (AUC = 0.953) than PC MRV (AUC = 0.871). Intermodality agreement of enhanced T1 SPACE (rk = 0.895 and weighted ĸ = 0.868) was better than PC MRV (rk = 0.753 and weighted ĸ = 0.653) compared with DSA. Thirty-seven intrasinus filling defects were detected by contrast-enhanced T1 SPACE, while only twenty of them were detected on source imaging of PC MRV. CONCLUSIONS: The contrast-enhanced T1 SPACE sequence was more sensitive and specific compared with PC MRV in assessing stenosis and detecting lesions in TSS patients. Accurate determination of the presence and extent of TSS using this technique might be useful in patient selection and guiding the treatment.

Neuroform EZ Stenting for Symptomatic Intracranial Artery Stenosis: 30 Days Outcomes in a High-Volume Stroke Center.

Objective: To test whether Neuroform EZ stent placement combined with the modified techniques in symptomatic severe intracranial stenosis (ICAS) would result in lower rates of peri-procedural complications of intracranial stenting. Methods: We retrospectively reviewed the clinical data from 71 consecutive patients who underwent Neuroform EZ stent placement combined with the modified techniques for symptomatic severe ICAS at our institute between January 2016 and October 2017. The primary outcomes were ipsi-lateral ischemic stroke, intra-cerebral hemorrhage, or death within 30 days after stenting. The secondary outcome was technical success. Results: The technical success rate was 100%. The mean pre and post-stent stenoses were 84.2% ± 9.1% (median 85%, IQR75% to 90%) and 16.9% ± 10.2 % (median 15%, IQR 10% to 25%). The frequency of ipsi-lateral stroke, intra-cerebral hemorrhage, or death within 30 days was 0%. Conclusions: The combined use of Neuroform EZ stent placement and the modified techniques for symptomatic severe ICAS is technically feasible and safe, with very low peri-procedural complications. Further studies are required to assess the long-term results of this approach.

Rescue Glue Embolization of Vessel Perforation During Mechanical Thrombectomy for Acute Ischemic Stroke: Technical Note.

BACKGROUND: Vessel perforation is a serious technical complication during mechanical thrombectomy (MT) for the treatment of acute ischemic stroke with large vessel occlusion. Routine rescue strategy includes balloon occlusion for tamponade, procedure suspension, and lowering or normalizing blood pressure. However, this complication is still associated with poor outcome and high mortality. METHODS: In this paper, the authors report their experience by using glue to embolize the ruptured vessel secondary to microcatheter/microwire perforation, preventing further deterioration in clinical outcome. Rescue glue embolization was attempted in 2 patients who developed intraprocedural vessel perforation while trying to gain access through the blocked artery with a microcatheter/microwire. RESULTS: The ruptured vessels were effectively occluded. Stent retriever thrombectomies were then continued, and TICI 2b and 3 recanalizations were achieved. Both patients' neurologic status improved. CONCLUSIONS: The key benefit of this method exists in embolizing the ruptured vessel without affecting the following MT. We propose the rescue glue embolization is simple yet effective in managing vessel perforation complication during MT.

Band Offset Measurements in Atomic-Layer-Deposited Al2O3/Zn0.8Al0.2O Heterojunction Studied by X-ray Photoelectron Spectroscopy.

Pure aluminum oxide (Al2O3) and zinc aluminum oxide (Zn x Al1-x O) thin films were deposited by atomic layer deposition (ALD). The microstructure and optical band gaps (E g ) of the Zn x Al1-x O (0.2 ≤ x ≤ 1) films were studied by X-ray diffractometer and Tauc method. The band offsets and alignment of atomic-layer-deposited Al2O3/Zn0.8Al0.2O heterojunction were investigated in detail using charge-corrected X-ray photoelectron spectroscopy. In this work, different methodologies were adopted to recover the actual position of the core levels in insulator materials which were easily affected by differential charging phenomena. Valence band offset (ΔE V) and conduction band offset (ΔE C) for the interface of the Al2O3/Zn0.8Al0.2O heterojunction have been constructed. An accurate value of ΔE V = 0.82 ± 0.12 eV was obtained from various combinations of core levels of heterojunction with varied Al2O3 thickness. Given the experimental E g of 6.8 eV for Al2O3 and 5.29 eV for Zn0.8Al0.2O, a type-I heterojunction with a ΔE C of 0.69 ± 0.12 eV was found. The precise determination of the band alignment of Al2O3/Zn0.8Al0.2O heterojunction is of particular importance for gaining insight to the design of various electronic devices based on such heterointerface.

The anti-metastatic effect of baicalein on colorectal cancer.

Baicalein, a naturally occurring flavonoid isolated from the roots of Scutellaria baicalensis, is historically and widely used as anti-inflammatory and anticancer therapy. Nevertheless, the anti-metastatic effect and underlying molecular mechanisms of baicalein on colorectal carcinoma (CRC) remain unclear. The aim of the present study was, therefore, to invastigate the anti-metastatic activity of baicalein and related mechanism(s) on CRC cells. In this study, we observed that baicalein treatment inhibited proliferation, as well as migration and invasion of HT-29 and DLD1 cells. Baicalein decreased the expression of the matrix metalloproteinases-2 (MMP-2) and MMP-9 in a dose-dependent manner. Also, baicalein treatment significantly reduced phosphorylation of extracellular signal regulated kinases (ERK). Furthermore, in DLD1 cells, MEK1 overexpression partially blocked the anti-metastatic effects of baicalein. Combined treatment with an ERK inhibitor (U0126) and baicalein led to the synergistic reduction of MMP-2/9 expression; and the invasive capabilities of DLD1 cells were also inhibited markedy. Finally, intragastric administration of baicalein inhibited CRC xenograft growth in vivo and suppressed the phosphorylation of ERK and the expression of MMP-2/9 in tumor tissues. Consequently, baicalein suppresses CRC cell invasion via inhibition of the ERK signaling pathways, indicating that baicalein is a potential agent for CRC treatment.

Nano-oxide thin films deposited via atomic layer deposition on microchannel plates.

Microchannel plate (MCP) as a key part is a kind of electron multiplied device applied in many scientific fields. Oxide thin films such as zinc oxide doped with aluminum oxide (ZnO:Al2O3) as conductive layer and pure aluminum oxide (Al2O3) as secondary electron emission (SEE) layer were prepared in the pores of MCP via atomic layer deposition (ALD) which is a method that can precisely control thin film thickness on a substrate with a high aspect ratio structure. In this paper, nano-oxide thin films ZnO:Al2O3 and Al2O3 were prepared onto varied kinds of substrates by ALD technique, and the morphology, element distribution, structure, and surface chemical states of samples were systematically investigated by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoemission spectroscopy (XPS), respectively. Finally, electrical properties of an MCP device as a function of nano-oxide thin film thickness were firstly studied, and the electrical measurement results showed that the average gain of MCP was greater than 2,000 at DC 800 V with nano-oxide thin film thickness approximately 122 nm. During electrical measurement, current jitter was observed, and possible reasons were preliminarily proposed to explain the observed experimental phenomenon.

Waffle-cone technique using solitaire AB stent for endovascular treatment of complex and wide-necked bifurcation cerebral aneurysms.

INTRODUCTION: To explore the safety and opportunity of the "waffle-cone" technique for the treatment of intracranial aneurysm. METHODS: From November 2009 and May 2012, consecutive data were collected from 136 patients with aneurysms treated by the stent-assisted coiling procedure. Six of these patients were treated using the "waffle-cone" technique. RESULTS: All the 6 patients were complex, wide-neck, bifurcation cerebral aneurysms. And the angles between the parent artery and distal vessels are acute. Two ruptured aneurysms located at the terminus of basilar artery, three ruptured aneurysms located at the anterior communicating artery, and one ruptured aneurysm located at trifurcation MCA. All the 6 patients were treated using the "waffle-cone" technique, 4 patients had Raymond classification Class I and 2 patients had Class II after the procedure. No complications occurred perioperative. There were no lesion-related strokes or deaths during the 6-month follow-up period. CONCLUSIONS: The "waffle-cone" technique is a safe, simple and alternative for the complex, wide-necked bifurcation aneurysms with acute angles between the parent artery and distal vessels. Long-term following-up results are needed to evaluate the efficacy of this technique.

[Comparative study of right anterolateral minithoracotomy and median sternotomy in the repair of atrial septal defects].

OBJECTIVE: To compare the effect of right anterolateral minithoractomy and median sternotomy for atrial septal defect closure. METHODS: In this study, 82 patients, whose age ranged from 4 to 46 years with a mean of 15.7+/-8.6 years, underwent surgical repair of the atrial septal defects on the beating heart through right anterolateral minithoractomy. Ten of these cases were complicated by moderate to severe pulmonary hypertension, and 3 by partial anomalous pulmonary venous connection. Another 67 patients with an age range of 3 to 49 years (mean 17.0+/-12.5 years) underwent surgical repair of the atrial septal defects through full-length median sternotomy with the heart beat arrested, and complication of moderate to severe pulmonary hypertension was identified in 11 cases and partial anomalous venous connection in 5. Comparisons were performed between the 2 groups in terms of the length of skin incision, cardiopulmonary bypass (CPB) time, postoperative mechanical ventilation time, intensive care unit stay, postoperative hospital stay, and the volume of postoperative drainage. RESULTS: There was no operative mortality in either of the 2 groups. In the former group, the CPB time (35.2+/-14.1 min), postoperative mechanical ventilation time (6.5+/-2.5 h), postoperative drainage volume (237.6+/-172.5 ml), postoperative hospital stay (7.4+/-1.2 d) and skin incision length (6.5+/-0.9 cm) were all significantly less than those of the latter group of patients, whose CPB time was 42.7+/-11.8 min, postoperative mechanical ventilation time 7.9+/-3.8 h, postoperative drainage volume 304.3+/-192.4 ml, postoperative hospital stay 9.0+/-2.9 d and skin incision length 15.9+/-1.7 cm (P < 0.01). The intensive care unit stay did not differ significantly between the 2 groups (35.1+/-16.2 h vs 32.3+/-24.1 h, P > 0.05). CONCLUSION: A right anterolateral minithoracotomy for repairs of atrial septal defects is a safe, effective and simple technique to ensure minimal surgical invasion with shorter postoperative hospital stay. Minithoracotomy can be performed to replace median sternotomy in the correction of atrial septal defects, including those complicated by partial anomalous pulmonary venous connection.

Diagnosis and surgical treatment of ruptured aneurysm in sinus of Valsalva.

OBJECTIVE: To evaluate the methods used to diagnose and surgically treat ruptured aneurysm in sinus of Valsalva (RASV). METHODS: Thirty-seven hospitalized patients with ruptured aneurysms in the sinus of Valsalva from September 1981 to April 2001, including 21 cases (56.7%) of RASV associated with ventricular septal defects (VSD) and 11 (29.7%) with aortic valvular prolapse were given surgical interventions. Under hypothermia and extracorporeal circulation, we successfully performed the surgical correction of RASV for all 37 patients VSD repair in 21 patients, aortic valvuloplasty in 6 and aortic valvular replacement in 2. RESULTS: There was no hospital deaths among these patients, although residual shunting occurred in two patients and acute renal failure was found one. Follow-up study of one month to 20 years in the patients undergoing repair of RASV revealed that the mostly individuals treated with operation obtained satisfactory cardiac function. CONCLUSION: Correct diagnosis of ruptured aneurysm in sinus of Valsalva should be confirmed immediately and surgical correction should be carried out as soon as possible.