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A series of (E)-1,2-diaryldigermenes, (Eind)ArGe＝GeAr(Eind) [Ar = phenyl (2), thiophen-2-yl (3), 9,9-dimethyl-2-fluorenyl (4) and 2,2′-bithiophen-5-yl (5)], supported by the fused-ring bulky 1,1,3,3,5,5,7,7-octaethyl-s-hydrindacen-4-yl (Eind) groups, have been obtained as yellow-orange to red crystalline solids by the reaction of 1,2-dibromodigermene, (Eind)BrGe＝GeBr(Eind) (1), with ArLi. In the crystals of 2–5, the digermene cores show a flexible nature adopting a trans-bent geometry with the trans-bent angles () between the Ge–Ge vector and the CEind–Ge–CAr plane of 34.04(12)° (2), 38.3(3)° and 38.8(3)° (3), 33.69(12)° (4) and 39.30(13)° (5). In the UV-vis spectra, strong π–π* absorptions have been observed with an absorption maximum at 451 nm (ε = 1.3 × 104) (2), 455 nm (ε = 9.7 × 103) (3), 480 nm (ε = 1.3 × 104) (4) and 497 nm (ε = 1.4 × 104) (5), retaining the Ge＝Ge double bond in solution. The absorption data and DFT calculations provide evidence for the intrinsic π-conjugation between the Ge＝Ge chromophore and aromatic rings involving the narrowing of the HOMO–LUMO gaps (ΔE) with the extension of the carbon π-electron systems. [ABSTRACT FROM AUTHOR]

Background: Paclitaxel-eluting technologies improve the clinical outcome of femoropopliteal (FP) occlusive disease. Several studies reported efficacy of the high-dose (nominal paclitaxel density of 3.5 μg/mm2) drug-coated balloon (DCB) for complex FP lesions. However, previous studies of DCB have shown a high rate of bailout stents, and few studies have compared the high-dose DCB with successful lesion pre-dilation without bailout stent and drug-eluting stent (DES) in chronic total occlusion (CTO) of the superficial femoral artery (SFA). This study aimed to compare the clinical outcome of high-dose DCB with successful lesion preparation and DES in CTO of the SFA.Methods: This was a single-center, retrospective study. From June 2018 to November 2020, we compared 41 patients (43 lesions) treated with high-dose DCB and 36 patients (37 lesions) treated with DES. The study period was defined as the period after DCB and DES became available simultaneously at our hospital, when all surviving patients had at least 1 year of follow-up. The primary endpoint was 12-month primary patency. The secondary endpoints were 12-month freedom from: (1) clinically driven target lesion revascularization (CD-TLR), and (2) re-occlusion.Results: Baseline clinical data were comparable between the two groups. Reference vessel diameter was smaller in the DCB group. The mean lesion and occlusion lengths were about the same in both groups. The subintimal angioplasty and bailout stent rate was 0% in the DCB group. The Kaplan-Meier estimate for 12-month primary patency was 92.0% in the DCB group and 87.2% in the DES group (p = 0.47). Freedom from CD-TLR also did not differ significantly between the two groups. The 12-month freedom from re-occlusion rate tended to be higher in the DCB group than in the DES group.Conclusions: High-dose DCB with successful lesion preparation showed 12-month clinical outcomes comparable with DES for CTO of the SFA, even without bailout stents. [ABSTRACT FROM AUTHOR]

The demand for endovascular therapy is increasing in an aging society, but the problem of restenosis in the chronic phase has not been resolved in femoropopliteal occlusive disease. Few studies have compared drug-coated balloon (DCB) and scaffold devices in chronic total occlusion (CTO) of the superficial femoral artery (SFA). This study aimed to compare DCBs with scaffold in patients with CTO of the SFA. This was a single-center, retrospective study. From June 2018 to December 2019, we compared 31 patients and 33 limbs treated with DCBs and 44 patients and 45 limbs treated with a stent or stent-graft (scaffold) for SFA CTO. The primary endpoint was 12-month primary patency. The secondary endpoints were 12-month freedom from clinically driven target lesion revascularization (CD-TLR) and 12-month freedom from re-occlusion. The DCBs were performed using an intravascular ultrasound (IVUS)-guided approach or a non-loop wire technique. Baseline characteristics were similar between the groups. An intraluminal approach was performed to use all DCBs. The bailout stent rate was 0% in the DCB group. Kaplan–Meier analysis showed that rates of 12-month primary patency tended to be higher in the DCB than in the scaffold group (92.7 vs. 76.6%, p = 0.073) and that freedom from CD-TLR also did not differ significantly between the two groups (96.8 vs. 86.3%, p = 0.17). Kaplan–Meier analysis also showed that the 12-month freedom from re-occlusion rate was significantly less in the Scaffold than in the DCB group (96.8 vs. 79.3%, p = 0.045). Therefore, we concluded that in treatment for CTO of the SFA, a DCB with intraluminal angioplasty without bailout stenting was less re-occlusion compared with scaffold. [ABSTRACT FROM AUTHOR]

To improve the dielectric strength in vacuum, spark conditioning through repetitive breakdowns by AC or impulse voltage is an effective method. AC conditioning at commercial power frequencies has been widely used due to its cost‐effectiveness, but the breakdown voltage after AC conditioning is generally lower compared to impulse conditioning. We have confirmed that multiple breakdowns occur successively in a half cycle of AC voltage application. It is considered that the multiple breakdowns are harmful for conditioning and triggered due to the previous breakdown in the same half cycle. In this paper, we discuss dielectric strength improvement by high frequency AC conditioning and how the multiple breakdowns are induced. We experimentally confirmed that the AC conditioning effect is improved by increasing the frequency of AC voltage for different applied AC conditioning voltages in a sphere‐plane electrode system. We focused on the breakdown position from the light emission images during AC conditioning to investigate whether the multiple breakdowns were induced or affected by the previous breakdown. We found that the multiple breakdowns occurred close to the previous breakdown position. The multiple breakdowns would be induced by the collision of metal particles due to the previous breakdown with the counter electrode. These breakdowns do not contribute to removing protrusion and would lead to damage to the electrode surface. The increasing frequency of AC conditioning would suppress the multiple breakdowns and improve the dielectric strength in vacuum. © 2024 The Author(s). IEEJ Transactions on Electrical and Electronic Engineering published by Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

A neutral silylyne complex of molybdenum was synthesized by the stepwise dehydrogenation method and its properties were compared with those of the tungsten analog. The complex takes a dimeric form as crystals but afford a monomer‐dimer equilibrium in solution. The replacement of the central metal from W to Mo led to a monomer dominant (~98 %) solution at room temperature. The monomer‐dimer dynamics was investigated based on thermodynamic parameters. The molybdenum silylyne complex underwent [2+2] cycloaddition with alkynes much faster than the tungsten analog. The reactions with organic azides led to the formation of the first example of silaiminoacyl complexes through [2+3] cycloaddition. The structures and bonding aspects of the products were clarified by multiple measurements and DFT calculations. [ABSTRACT FROM AUTHOR]

Clinical trials have demonstrated the efficacy of a balloon-expandable covered stent (CS) for aortoiliac occlusive disease (AIOD). However, the real-world clinical outcomes and the underlying factors remain unclear. We assessed the clinical outcomes and factors associated with primary patency after implantation of a balloon-expandable CS for patients with complex AIOD. This prospective multicenter observational study enrolled 149 consecutive patients undergoing VIABAHN® VBX-CS (W.L. Gore & Associates, Flagstaff, AZ) implantation for complex AIOD (age, 74 ± 9 years; male, 74%; diabetes mellitus, 46%; renal failure on dialysis, 23%; chronic limb-threatening ischemia, 26%). The primary study endpoint was 1-year primary patency, and the secondary endpoints were procedural complications, freedom from occlusion, clinical-driven target lesion revascularization (CD-TLR), and surgical revision at 1 year. Risk factors for restenosis were explored using random survival forest analysis. The median follow-up period was 13.1 months (interquartile range 9.7–14.0 months). Procedural complications were observed in 6.7% of the patients. The 1-year primary patency was 94.8% (95% confidence interval 91.0–98.6%), while the 1-year freedom rate from occlusion, CD-TLR, and surgical revision rates were 96.5% (93.5–99.5%), 94.7% (90.9–98.6%), and 97.8% (95.4–100%), respectively. The presence of chronic total occlusion, aortic bifurcation lesion, the number of disease regions, and TASC-II classification was significantly associated with the restenosis risk. In contrast, the calcification severity, IVUS use, IVUS parameters were not associated with restenosis risk. We observed excellent 1-year real-world outcomes after implantation of a balloon-expandable CS for complex AIOD; only a few perioperative complications occurred. [ABSTRACT FROM AUTHOR]

Isolated atherosclerotic popliteal lesions (IAPLs) have been considered challenging. This study aimed to investigate the efficacy of endovascular therapy (EVT) using the newer devices for IAPLs. This retrospective multicenter registry analyzed patients with lower extremity artery disease having IAPLs who underwent EVT using the newer devices between 2018 and 2021. The primary outcome was primary patency 1 year after EVT. A total of 392 consecutive patients undergoing EVT for IAPLs were enrolled. The Kaplan–Meier analysis showed that the primary patency and the freedom from target lesion revascularization were 80.9% and 87.8% 1 year after EVT, respectively. The multivariate Cox proportional hazards regression analysis showed that the clinical features that were independently associated with restenosis risk were drug-coated balloon (DCB) use for younger age (< 75 years old; adjusted hazard ratio, 3.08 [95% confidence interval 1.08–8.74]; P = 0.035), non-ambulatory status (2.74 [95% confidence interval 1.56–4.81]; P < 0.001), cilostazol use (0.51 [95% confidence interval 0.29–0.88]; P = 0.015), severe calcification (1.86 [95% confidence interval 1.18–2.94]; P = 0.007), and small external elastic membrane (EEM) area measured by intravascular ultrasound (IVUS) (< 30 mm2) (2.07 [95% confidence interval 1.19–3.60]; P = 0.010). From the univariate analysis, among patients treated with DCB, younger patients (n = 141) were associated with more comorbidities including smoking (P < 0.001), diabetes mellitus (P < 0.001), end-stage renal disease (P < 0.001), history of revascularization (P = 0.046) and small EEM area (P = 0.036), compared to older patients (n = 140). Moreover, smaller post-procedural minimum lumen area measured by IVUS after DCB dilatation was observed in younger patients (12 ± 4 vs. 14 ± 4 mm2, P = 0.033). This retrospective study demonstrated that the current EVT provided an acceptable 1-year primary patency rate in patients with IAPLs. The primary patency was lower following DCB in younger patients, likely due to the higher rates of comorbidities in this patient population. [ABSTRACT FROM AUTHOR]

Functionally graded materials (FGM) application with graded permittivity and conductivity is promising as an effective technique for electric field relaxation in SF6 gas around HVDC gas insulated switchgear (GIS)/gas insulated transmission line (GIL) spacers. To approach the practical application of FGM to HVDC GIS/GIL spacers, this article investigates the electric field reduction effect given by permittivity and conductivity graded materials ($\varepsilon /\sigma $ -FGM) based on actual measured permittivity ($\varepsilon $) characteristics of SrTiO3-filled epoxy composites and conductivity ($\sigma $) characteristics of SiC-filled epoxy composites. In addition, theoretical discharge inception voltage (TDIV) of $\varepsilon /\sigma $ -FGM spacer is calculated under standard lightning impulse (LI) voltage based on the volume–time theory. The results show that the $\varepsilon /\sigma $ -FGM spacer with grading to lower permittivity (GLP) ($\varepsilon _{r}$ from 12.7 to 4) containing 0–26.9-vol% SrTiO3-filled epoxy composite and U-shaped graded conductivity containing 5–10-vol% SiC-filled epoxy composite is effective for electric field relaxation under DC steady state (DC-SS) and LI voltage where both resistive and capacitive fields present. It is attributed to the higher $\varepsilon $ and $\sigma $ of FGM spacer near the HV conductor/spacer interface. TDIV under LI voltage is also estimated to be 26% higher at 0.5 MPa-abs, compared with the conventional spacer without $\varepsilon /\sigma $ grading. [ABSTRACT FROM AUTHOR]

Drug-eluting devices improved outcomes of endovascular therapy (EVT) for femoropopliteal lesions, but mainly for de novo lesions. Endovascular therapy for in-stent restenosis/occlusion (ISR/O) is challenging, and large trials and long-term data are not well reported.This study is a physician initiated, multicenter, and retrospective design. From 7 Japanese institutes, 3635 femoropopliteal cases were enrolled in the study. Among these, 346 cases of first ISR/O were studied. We defined drug-coated-balloon, drug-eluting stent, and covered stent as New devices. Balloon angioplasty and bare nitinol stent were included in the control group.The propensity score matching extracted 112 pairs. At 12 months, the primary patency rate was 80.3% in the new device group and 52.7% in the control group, and there was a significant intergroup difference (P = .004). However, at 36 months, the rate was 43.3% vs 39.2%, with no significant difference (P = .090). No baseline characteristics had any significant interaction effect (all P > .05).The New devices were more effective than the control group for ISR/O at 1 year, but caught up at 3 years. [ABSTRACT FROM AUTHOR]

Purpose: Drug-eluting stents (DESs) play an important role in endovascular therapy (EVT) for femoropopliteal (FP) lesions. Cilostazol improves patency after bare-metal nitinol stent (BNS) implantation for femoropopliteal lesions. This study aimed to establish whether cilostazol is effective in improving the patency of DESs and determine whether BNS or DESs with or without cilostazol are more effective in improving the 12-month patency after EVT for FP lesions. Materials and methods: In this prospective, open-label, multicenter study, 85 patients with symptomatic peripheral artery disease due to de novo FP lesions were enrolled and treated with DESs with cilostazol from eight cardiovascular centers between April 2018 and May 2019. They were compared with 255 patients from the DEBATE SFA study, in which patients were randomly assigned to the BNS, BNS with cilostazol, or DES groups. The primary endpoint was the 12-month patency rate using duplex ultrasound (peak systolic velocity ratio < 2.5). This study was approved by the ethics committee of each hospital. Results: The 12-month patency rates for the BNS, BNS with cilostazol, DES, and DES with cilostazol groups were 77.6%, 93.1%, 82.8%, and 94.2%, respectively (p = 0.007). The 12-month patency rate was higher in the DES with cilostazol group than in the DES group (p = 0.044). In small vessels, the DES with cilostazol group had a higher patency rate than the DES group (100.0% vs. 83.4%, p = 0.023). Conclusions: DES with cilostazol showed better patency than DES alone. Cilostazol improved patency after EVT with DES in FP lesions and small vessels. Clinical trial registration: University Hospital Medical Information Network Clinical Trials Registry (no. UMIN 000032473). [ABSTRACT FROM AUTHOR]

Spark conditioning is an effective method to increase the dielectric strength in vacuum by melting and removing micro-protrusions on the cathode surface. We aim to optimize the conditioning effect in vacuum for the application of vacuum circuit breakers (VCBs) to higher voltage levels. To obtain high breakdown (BD) voltage, the control of BD charge in the conditioning process is required. When a BD occurs, we have suggested that micro-protrusions can be generated on the cathode surface by particles from the anode. For the suitable control of BD charge, the meltability of generated micro-protrusions and their size are important. In this article, we focus on the generation of micro-protrusions on the cathode surface in conditioning process. First, we conduct spark conditioning by repetitive impulse voltages of rod–plane electrodes made of OFHC Cu in a vacuum chamber with different BD charges. Later, we observe the surface of rod cathode with a digital microscope in order to count the number of visible protrusions and measure their radii. By considering the meltability of micro-protrusions, we quantitatively reveal the existence of residual protrusions that cannot be completely melted by BD. Next, we estimate the maximum size of generated micro-protrusions by BD charge. In consideration of the collision of ions into the anode accelerated by the anode sheath voltage, we estimate the meltable amount of anode material by the BD charge. We confirm that the radii of experimentally measured protrusions are close to the estimated ones. Moreover, we consider the difference in dielectric strength due to the difference in the initial surface condition of the electrodes. We clarify that the dielectric strength is improved by applying acid wash and heat treatment to the electrodes before conditioning, which can be optimized by the BD charge and the initial surface condition of the electrode. [ABSTRACT FROM AUTHOR]