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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]

For extra-high-voltage high-temperature superconducting (HTS) cables, not only high electrical insulation performance but also low dielectric loss is required. Therefore, we focus on a porous synthetic paper with lower dielectric loss, e.g., Tyvek polyethylene nonwoven fabric, than that of polypropylene laminated paper (PPLP), which has been used for a conventional HTS cable insulation system. In this paper, we compare partial discharge inception characteristics for different liquid nitrogen/synthetic paper composite insulation systems. The partial discharge inception electric field strength in the composite insulation system depends on the electric field strength in the porous area of synthetic paper. [ABSTRACT FROM AUTHOR]

In this study we investigate the time and space transition characteristics of DC electric field in SF 6 gas from the initial state DC-on to final DC steady-state in gas-solid composite insulation systems. Using a simple rod-electrode configuration and actual insulating epoxy-spacer model, the electric field distributions of the epoxy-spacer in SF 6 gas and time constant T of electric field formation from DC-on to DC steady-state are calculated based on the electric conduction characteristics. In addition, the emerging electric field distributions due to accumulated charge on solid insulator surface are introduced to elucidate the time transition process of electric field stress in the gap between HV conductor and GND. As a result, we quantitatively clarify that the time constant T of electric field formation are highly dependent on the non-uniform factor η and location of the gap space in the electrode configuration under non-uniform DC electric field. The locations with higher electric field stress in the gap space have the shorter time constant T. In addition, the time transition process of electric field stress in SF 6 gas depends on the gap space and the location of maximum electric field change during time transition. Especially, we clarify that the highest electric field stress in SF 6 gas may emerge in actual GIS structure based on the time transition process of emerging electric field due to accumulated charge. [ABSTRACT FROM AUTHOR]

The efficacy of multimodality image fusion road-mapping technique for endovascular therapy has been reported recently. Our aim was to evaluate the efficacy of endovascular therapy (EVT) with three-dimensional (3D) road mapping by fusing computed tomography (CT) and angiographical volumetric data for aorto-iliac chronic total occlusion (CTO). We retrospectively analyzed 36 patients with aorto-iliac CTO from June 2017 to November 2019 and classified them into two groups: EVT using a CT fused 3D roadmap (CTf3D-RM; 3D group, n = 14) and standard EVT (standard group, n = 22). Primary endpoint was wiring time and secondary endpoints were procedural success rate, number of guidewires, procedure time, radiation dose, contrast medium dose, and complications. Wiring time was significantly shorter in the 3D group than the standard group (3D, 15.6 ± 10.23 min vs. standard, 44.6 ± 35.3 min; p = 0.0052). Both groups had high procedural success rates (3D, 100% vs. standard, 100%) and low complication rates (3D, 0.0% vs. standard, 9.1%; p = 0.51). There were significantly fewer guidewires in the 3D group than the standard group (3D, 2.78 ± 1.31 vs. standard, 4.36 ± 2.01; p = 0.0138). The 3D group trended towards shorter procedural time (3D, 78.8 ± 32.5 min vs. standard, 107.5 ± 52.5 min; p = 0.076), lower radiation dose (3D, 28.6 ± 18.9 Gycm2 vs. standard, 48.9 ± 49.2 Gycm2; p = 0.15), and lower contrast medium dose (3D, 102.2 ± 30.6 vs. standard, 127.5 ± 51.3; p = 0.11) than the standard group. Therefore, we concluded that EVT with CTf3D-RM is effective for aorto-iliac CTO. This method may improve the quality of aorto-iliac CTO interventions. [ABSTRACT FROM AUTHOR]

This study was performed to evaluate the efficacy and safety of endovascular therapy (EVT) by diluted contrast digital subtraction angiography (DSA) in patients with chronic kidney disease (CKD). Patients with peripheral artery disease (PAD) often have CKD; thus, EVT carries a risk of contrast-induced nephropathy (CIN). Reducing the amount of contrast medium is, therefore, important in these patients. We developed a novel EVT method using DSA with diluted contrast medium. DSA parameters were adjusted for diluted contrast angiography (1:10 dilution), and we defined this technique as low-concentration DSA (LC-DSA). We retrospectively analyzed 122 patients with CKD [estimated glomerular filtration rate (eGFR), < 45 mL/min/1.73 m2] from June 2012 to November 2017 and classified them into two groups: EVT with diluted contrast (LC-DSA group, n = 63) and conventional EVT (control group, n = 59). Patients with aortoiliac lesions and those undergoing hemodialysis were excluded. The primary endpoint was the incidence of CIN as defined by an absolute increase in serum creatinine of ≥ 0.5 mg/dL or relative increase of ≥ 25% 2–5 days after the procedure. The secondary endpoints were worsening renal function (defined as an eGFR reduction of ≥ 25% compared with that before the procedure), the amount of contrast medium used for EVT, freedom from complications related to LC-DSA, and procedural success. The incidence of CIN was significantly lower in the LC-DSA group than control group (0.0% vs. 11.9%, respectively; P = 0.001). The absolute eGFR increase (4.25 ± 4.7 vs. 1.24 ± 6.9, respectively; P = 0.005) and creatinine decrease (− 0.16 ± 0.2 vs. 0.007 ± 0.34, respectively; P = 0.0078) were greater in the LC-DSA group than control group. Less contrast medium was used in the LC-DSA group than control group (30.0 ± 14.6 vs. 117.9 ± 52.8 mL, respectively; P < 0.0001). There were no differences in the procedural success rate (100% vs. 96.6%, P = 0.23) or complications related to LC-DSA (0.0% vs. 1.7%, P = 0.48). Therefore, we concluded that EVT with diluted contrast DSA reduced the amount of contrast medium and incidence of CIN. This method is effective and safe for treating patients with CKD who have infrainguinal lesions. [ABSTRACT FROM AUTHOR]

Sterically large substituents can provide kinetic stabilization to various types of low-coordinate compounds. For example, regarding the chemistry of the group 14 elements, since West et al. introduced the concept of kinetic protection of the otherwise highly reactive Si=Si double bond by bulky mesityl (2,4,6-trimethylphenyl) groups in 1981, a number of unsaturated compounds of silicon and its group homologs have been successfully isolated by steric effects using the appropriate large substituents. However, the functions and applications of the Si-Si π-bonds consisting of the 3pπ electrons on the formally sp 2-hybridized silicon atoms have rarely been explored until 10 years ago, when Scheschkewitz and Tamao independently reported the model systems of the oligo(p-phenylenedisilenylene)s (Si-OPVs) in 2007. This review focuses on the recent advances in the chemistry of π-electron systems containing Si=Si double bonds, mainly published in the last decade. The synthesis, characterization, and potential application of a variety of donor-free π-conjugated disilene compounds are described. [ABSTRACT FROM AUTHOR]

For electric field grading in GIS spacers, the application of functionally graded materials (FGM) with spatial distribution of dielectric permittivity (ε) can be one effective solution. In this paper, we propose the flexible mixture casting (FMC) method as a novel and practical technique to fabricate ε-FGM for GIS spacers. We verified that the relative permittivity (er) can be controlled from εr = 4 to εr = 30 by varying the loading ratio of high permittivity filler particles under the FMC method. Toward the practical application of ε-FGM, we verified the relaxation effect of maximum electric field strength and the improvement effect of discharge inception voltage in SF6 gas in a simplified GIS spacer model using ε-FGM under the FMC method. Simulation results revealed that the maximum electric field strength can be effectively reduced and the discharge inception voltage can be significantly improved compared with using a constant and uniform permittivity. [ABSTRACT FROM AUTHOR]

The reactions of the fused-ring bulky Eind-substituted 1,2-dibromodisilene, (Eind)BrSi=SiBr(Eind) (1a) (Eind = 1,1,3,3,5,5,7,7-octaethyl-s-hydrindacen-4-yl (a)), with N-heterocyclic carbenes (NHCs) (Im-Me4 = 1,3,4,5-tetramethylimidazol-2-ylidene and Im-iPr2Me2 = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) are reported. While the reaction of 1a with the sterically more demanding Im-iPr2Me2 led to the formation of the mono-NHC adduct of arylbromosilylene, (Im-iPr2Me2)→SiBr(Eind) (2a'), a similar reaction using the less bulky Im-Me4 affords the bis-NHC adduct of formal arylsilyliumylidene cation, [(Im-Me4)2→Si(Eind)]+[Br-] (3a). The NHC adducts 2a' and 3a can also be prepared by the dehydrobromination of Eind-substituted dibromohydrosilane, (Eind)SiHBr2 (4a), with NHCs. The NHC-coordinated silicon compounds have been characterized by spectroscopic methods. The molecular structures of bis-NHC adduct, [(Im-iPr2Me2)2→Si(Eind)]+[Br-] (3a'), and 4a have been determined by X-ray crystallography. [ABSTRACT FROM AUTHOR]

1,2-Dihalodigermenes, (E)-(Eind)XGe=GeX(Eind) (X = Br and Cl), bearing the fused-ring bulky Eind group (Eind = 1,1,3,3,5,5,7,7-octaethyl-s-hydrindacen-4-yl) have been isolated as orange-yellow crystals by the ligand redistribution reaction between the diarylgermylene, (Eind)2Ge:, and GeX2·dioxane in toluene via the cleavage and recombination of the Ge–C and Ge–X bonds. The dihalodigermenes have a Ge=Ge double bond character in the crystalline state, but dissociate into halogermylenes, (Eind)XGe:, in solution. The addition of excess LiBr to the THF solution of the bromogermylene, (Eind)BrGe:, led to the formation of an equilibrium mixture containing the lithium bromogermylenoid, [Li+][(Eind)GeBr2]−. The bromogermylenoid can be isolated as a cryptand-separated potassium ion pair, [K+(crypt-222)][(Eind)GeBr2]−, which has been structurally characterized. [ABSTRACT FROM AUTHOR]

Toward the practical development of high-voltage high-temperature superconducting (HTS) cables, high electrical insulation characteristics, and low dielectric loss become important. Dielectric loss drastically increases with the increase of operation voltage of HTS cables. Therefore, it is highly expected to find a novel insulating material with low dielectric loss for the high-voltage HTS cables. We have focused on Tyvek ^\circledR, polyethylene (PE) nonwoven fabric, and Tyvek ^\circledR/PE, a syntactic paper bonding PE-sheet on Tyvek^\circledR by heat, as low dielectric loss materials. In this paper, we investigated fundamental partial discharge inception characteristics and their mechanisms of Tyvek^\circledR immersed in liquid nitrogen (LN2).In addition, we compared the electrical insulation characteristics of Tyvek^\circledR, Tyvek ^\circledR/PE, and polypropylene laminated paper (PPLP^\circledR), and discussed their mechanisms. [ABSTRACT FROM PUBLISHER]

The reaction of the bulky diphosphenes (Rind)P=P(Rind) ( 1; Rind=1,1,3,3,5,5,7,7-octa-R-substituted s-hydrindacen-4-yl) with two molecules of N-heterocyclic carbene (NHC; 1,3,4,5-tetramethylimidazol-2-ylidene) resulted in the quantitative formation of the NHC-bound phosphinidenes NHC→P(Rind) ( 2), along with the cleavage of the P=P double bond. The reaction times are dependent on the steric size of the Rind groups (11 days for 2 a (R=Et) and 2 h for 2 b (R=Et, Me) at room temperature). The mechanism for the double bond-breaking is proposed to proceed via the formation of the NHC-coordinated, highly polarized diphospehenes 3 as an intermediate. Approach of a second NHC to 3 induces P−P bond cleavage and P−C bond formation, which proceeds through a transition state with a large negative Gibbs energy change to afford the two molecules of 2, thus being the rate-determining step of the overall reaction with the activation barriers of 80.4 for 2 a and 29.1 kJ mol−1 for 2 b. [ABSTRACT FROM AUTHOR]

The reaction of the bulky diphosphenes (Rind)P=P(Rind) ( 1; Rind=1,1,3,3,5,5,7,7-octa-R-substituted s-hydrindacen-4-yl) with two molecules of N-heterocyclic carbene (NHC; 1,3,4,5-tetramethylimidazol-2-ylidene) resulted in the quantitative formation of the NHC-bound phosphinidenes NHC→P(Rind) ( 2), along with the cleavage of the P=P double bond. The reaction times are dependent on the steric size of the Rind groups (11 days for 2 a (R=Et) and 2 h for 2 b (R=Et, Me) at room temperature). The mechanism for the double bond-breaking is proposed to proceed via the formation of the NHC-coordinated, highly polarized diphospehenes 3 as an intermediate. Approach of a second NHC to 3 induces P−P bond cleavage and P−C bond formation, which proceeds through a transition state with a large negative Gibbs energy change to afford the two molecules of 2, thus being the rate-determining step of the overall reaction with the activation barriers of 80.4 for 2 a and 29.1 kJ mol−1 for 2 b. [ABSTRACT FROM AUTHOR]

An innovation for the higher performance and reliability of electric power apparatus can be brought about by a novel technique on electrical insulating materials. The application of functionally graded materials (FGM) with spatial distribution of dielectric permittivity in solid insulator is an effective technique to contribute to the above innovation, because FGM can control the electric field distribution with a simple shape. In this paper, we investigated the fabrication and simulation techniques of FGM with various spatial distributions of dielectric permittivity using centrifugal force. Firstly, we developed a simulation technique to estimate the dielectric permittivity distribution of FGM by considering the particle movement in a viscous fluid under centrifugal force. Secondly, based on the simulation technique, we fabricated FGM samples with various relative permittivity distribution and confirmed the validity of the simulation technique. Consequently, the fabrication results provided a good agreement with the simulation results. [ABSTRACT FROM PUBLISHER]

(Z)-1,2-Di(1-pyrenyl)disilene containing bulky 1,1,3,3,5,5,7,7-octaethyl-s-hydrindacen-4-yl (Eind) groups has been obtained as purple crystals by the reductive coupling reaction of the corresponding dibromosilane with lithium naphthalenide. An X-ray crystallographic analysis revealed an Eind- and pyrenyl-meshed molecular gear around the disilene core adopting the Z configuration, in which the two pyrenyl groups intramolecularly interact through the π--π stacking with a distance of 3.635 Å between the centers of the two pyrene rings. The disilene &#960-system exhibits a &#960(Si--Si) → π*(pyrene) intramolecular charge-transfer (ICT) fluorescence at room temperature, whose wavelengths depend on the solvent polarity. The photophysical properties are theoretically supported by computational studies including excited-state calculations. [ABSTRACT FROM AUTHOR]

Toward the practical and rational insulation design of high temperature superconducting power apparatus, the ac breakdown (BD) characteristics and mechanisms of liquid nitrogen (LN2) were systematically investigated and discussed for different pressures at P = 0.1-0.3 MPa and temperatures at T = 65-77 K under quasiuniform electric field with the field utilization factor ζ= 0.986-0.674. We obtained the BD strength (EB) in sub-cooled LN2 (SLN2) and analyzed them in terms of size effect, taking account of the stressed liquid volume (SLV) with the electric field distribution in SLN2. Together with the other researchers? data on BD characteristics of LN2, we extended the evaluation by applying the concept of α% SLV (SLV with the electric field strength higher than the decisive electric field factor, α of the maximum electric field strength). As the result, we derived that EB with the 50 % probability decreased linearly with the increase in α% SLV on a universal line, EB = 78.4 x (α% SLV)-1/8.15, which was irrespective of the pressure and temperature of LN2. [ABSTRACT FROM AUTHOR]

Reactions of stable 1,2-dibromodisilenes (( E)-Ar(Br)SiSi(Br)Ar) with N-heterocyclic carbenes (NHC) afforded NHC-arylbromosilylene adducts or bromide salts of the corresponding bis-NHC adducts of the formal arylsilyliumylidene cations ([ArSi:]+). In some cases, an NHC was able to replace a bromide anion in the coordination sphere of the arylbromosilylene-NHC adduct. [ABSTRACT FROM AUTHOR]

We have been developing Superconducting Fault Current Limiting Transformer (SFCLT), which has multifunction of both a superconducting transformer in a steady state as well as a superconducting fault current limiter in a fault condition. This paper introduces the progress in our SFCLT project since 1998, from Step-1 to the latest Step-5, with the concept, design, fabrication and test results of SFCLT. In the latest Step-5, we developed a 2 MVA, 22/6.6 kV class SFCLT with YBCO coated conductors and verified the fundamental function as a transformer, effective current limiting function as a fault current limiter, and recovery characteristics after the fault clearance with its operational criterion. [ABSTRACT FROM AUTHOR]

Summary: The hexagonal P622 crystal of bacteriorhodopsin, which is made up of stacked membranes, is stable provided that the precipitant concentration in the soaking solution is higher than a critical value (i.e., 1.5 M ammonium sulfate). Diffraction data showed that the crystal lattice shrank linearly with increasing precipitant concentration, due primarily to narrowing of intermembrane spaces. Although the crystal shrinkage did not affect the rate of formation of the photoreaction M intermediate, its lifetime increased exponentially with the precipitant concentration. It was suggested that the energetic barrier of the M-to-N transition becomes higher when the motional freedom of the EF loop is reduced by crystal lattice force. As a result of this property, the M state accumulated predominantly when the crystal that was soaked at a high precipitant concentration was illuminated at room temperature. Structural data obtained at various pH levels showed that the overall structure of M is not strongly dependent on pH, except that Glu194 and Glu204 in the proton release complex are more separated at pH 7 than at pH 4.4. This result suggests that light-induced disruption of the paired structure of Glu194 and Glu204 is incomplete when external pH is lower than the pK a value of the proton release group in the M state. [Copyright &y& Elsevier]

Summary: To understand the functional role of apolar cavities in bacteriorhodopsin, a light-driven proton pump found in Halobacterium salinarum, we investigated the crystal structure in pressurized xenon or krypton. Diffraction data from the P622 crystal showed that one Xe or Kr atom binds to a preexisting hydrophobic cavity buried between helices C and D, located at the same depth from the membrane surface as Asp96, a key residue in the proton uptake pathway. The occupation fraction of Xe or Kr was calculated as ∼0.32 at a pressure of 1 MPa. In the unphotolyzed state, the binding of Xe or Kr caused no large deformation of the cavity. However, the proton pumping cycle was greatly perturbed when an aqueous suspension of purple membrane was pressurized with xenon gas; that is, the decay of the M state was accelerated significantly (∼5 times at full occupancy), while the decay of an equilibrium state of N and O was slightly decelerated. A similar but much smaller perturbation in the reaction kinetics was observed upon pressurization with krypton gas. In a glycerol/water mixture, xenon-induced acceleration of M decay became less significant in proportion to the water activity. Together with the structure of the xenon-bound protein, these observations suggest that xenon binding helps water molecules permeate into apolar cavities in the proton uptake pathway, thereby accelerating the water-mediated proton transfer from Asp96 to the Schiff base. [Copyright &y& Elsevier]

This paper discusses partial discharge (PD) propagation, degradation and lifetime characteristics of magnet wires for inverter-fed motor under surge voltage application. Experimental results showed the time variation of PD activity, i.e. intermittent PD, successive PD, critical PD and breakdown (BD), under repetitive surge voltage application with a fixed peak value. Critical PD was a drastic change of PD activity and was identified as the partial BD of magnet wires. Since the final BD was confirmed to be always induced at the critical PD location, the critical PD was regarded as an important indicator to determine the lifetime of magnet wires. The experimental results also clarified that the lifetime of magnet wires could be determined by the total number of PD generation from its inception to breakdown. PD activity was interpreted by the time transition of PD generation frequency, and its mechanisms were discussed. [ABSTRACT FROM AUTHOR]

This paper reviews the up-to-date research activities on electrical insulation techniques under repetitive surge voltages with steep wavefront for low voltage inverter-fed motors. Partial discharge (PD) inception, propagation, ageing and breakdown characteristics of magnet wires, including recently developed PD-resistant wires such as nanocomposite enameled wires, are described. PD measurement techniques under the steep-front voltages and IEC activity toward their standardization are also introduced. [ABSTRACT FROM AUTHOR]

In this paper, we investigated the thermal runaway characteristics of a conduction-cooled Bi2212 HTS coil with a 4 K-GM cryocooler system under compensating operation for load fluctuations. We measured the temporal evolutions of temperature and voltage distributions of the HTS solenoidal coil for typical current patterns of load fluctuation compensation at different ambient temperatures. On the basis of these experimental results, we constructed a thermal analysis model, and analysed the thermal runaway characteristics during and after the load fluctuation compensation. Based on the results of our experiments and the numerical simulations, we proposed criterion for the monitoring of an HTS SMES system during compensating operation for load fluctuations. [ABSTRACT FROM AUTHOR]

In inverter-fed motor coils, surge voltages with the rise time of several tens or hundreds of nano-second may cause partial discharge (PD) and degradation of electrical insulation performance of the inverter-fed motor coils. This paper discusses PD inception characteristics as well as PD propagation characteristics after PD inception for magnet wire of inverter-fed motor under surge voltage application. Experimental results firstly revealed that PD inception voltage (PDIV) decreased with the increase in the length of enamel-coated wire, which was evaluated in terms of the stressed wire contact length under surge voltage application, i.e. size effect. We proposed a regression line for the size effect on PDIV for the electrical insulation design of inverter-fed motor coils. Secondly, PD propagation characteristics were also investigated under the higher voltage application, and their mechanisms were discussed in terms of generation probability of initial electrons, space charge behavior in the wedge-shaped air gap, charging on the enamel surface and so on. [ABSTRACT FROM AUTHOR]

This paper describes the propagation characteristics and mechanisms of partial discharge (PD) leading to breakdown (BD) in electronegative gases such as SF6/N2 and C2F6/N2 gas mixtures for ac voltage application. An established PD measuring system of highly time-resolved PD current and light intensity waveforms, streak and light emission images enabled us to discuss the physical mechanisms of PD generation and propagation in terms of space charge behavior. Experimental results revealed that the time-resolved PD generation was divided into different groups composed of the first large PD and the subsequent small PDs; the former was identified as the leader discharge, and the latter corresponded to the streamer discharges. The successive generation of the streamer and leader discharges was interpreted by the change of critical volume size. The time-resolved PD generation characteristics leading to BD were also measured and discussed. The leader discharge would be obliged to take a detour along the periphery of the positive space charge area in the vicinity of the needle electrode, and finally result in BD in electronegative gases. [ABSTRACT FROM AUTHOR]

Insulating materials exist in a variety of different forms, including gas, liquid, solid, and vacuum, and different forms of insulating materials have significantly different dielectric strengths and insulating properties. Power transmission/substation facilities for UHV AC and 500 kV DC power transmission and 500 kV underground power transmission facilities have been designed and constructed by taking advantage of the insulating properties of various insulating materials and structures so that they conform to the demanded insulation specifications. Conventionally, insulating material technology has been developed by making a close study of apparatuses and insulating materials individually. In this paper, as a new attempt, the insulating properties of various insulating materials/apparatuses are cross-sectionally compared and examined from an entirely new viewpoint through the assessment of commonalities and differences between them. A listing of lightning impulse and AC dielectric strength data is prepared and systematically positioned from the standpoint of material and structure, and compared and evaluated in a unified way from the viewpoint of typical indices of insulating properties including the ‘n’ value of the V-t characteristic, Weibull parameters, and impulse ratio. Further, an insulation assessment of apparatuses is systematically made with consideration given to their sizes and structures as well as the insulating materials themselves. As a result, it was found, for example, that the design field strengths of power capacitors were high and those of generators were not, and there was a noticeable difference in design field strength between SF6 gas insulated apparatuses and oil-immersed transformers. It is expected that the analysis conducted from an entirely new angle may provide a new approach to the development of apparatus insulation technology and to the rationalization of insulation design. [ABSTRACT FROM AUTHOR]

We have investigated impulse partial discharge (PD) and breakdown (BD) characteristics of a needle-plane gap in N2/SF6 gas mixtures under positive lightning impulse voltage application, and discussed their physical mechanisms. The 50% probability PD inception voltage (PDIV50), leader discharge onset voltage (LOV) and BD voltage (BDV50) were measured and analyzed as a function of gas pressure and SF6 content. Experimental results revealed the stepwise propagation process of the impulse PD and enabled us to classify the impulse PD in N2/SF6 gas mixtures into two types, the streamer discharge and the leader discharge. We also discussed the impulse PD propagation mechanisms in terms of PD parameters such as propagation length, time interval and current pulse magnitude, and suggested a sequential relationship in the PD propagation process under non-uniform electric field. [ABSTRACT FROM AUTHOR]

A novel technique for partial discharge (PD) measurement and analysis (PD-CPWA PD Current Pulse Waveform Analysis) is developed and introduced in this paper. PD-CPWA is expected to be utilized to discuss PD mechanisms and physics in electrical insulating materials, focusing on the PD current pulse waveform and its time transition from PD inception to breakdown (BD). In this paper, the concept and principle of PD-CPWA are described, and the applications of PD-CPWA to (1) epoxy spacer samples under thermal and electric combined stresses in GIS, (2) creepage PD on epoxy spacers in SF6 gas and (3) liquid nitrogen / polypropylene laminated paper composite insulation system for high temperature superconducting cables are introduced and discussed. [ABSTRACT FROM AUTHOR]

We have been investigating the feasibility of a superconducting fault current limiting transformer (SFCLT) with the functions of fault current suppression and system stability improvement. This paper discusses these functions with consideration of overvoltage and thermal characteristics of SFCLT, and their dependence on recovery time into superconducting state after the quench of SFCLT. Simulation results using EMTP suggested that SFCLT would be coordinated with the background power system under the appropriate superconducting recovery time. The operating parameters of SFCLT were also optimized in a simplified power transmission model system. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 142(2): 40–47, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10070 [ABSTRACT FROM AUTHOR]

In Japan, electric power utilities purchase electricity from independent power producers (IPPs) through competitive bidding; the IPP evaluation is based on the avoided costs of corresponding generators of utilities. In this evaluation, however, nonpricing factors such as power flow constraints in the electric power system cannot be considered. In this paper, we propose a new approach to evaluate economic impacts of IPPs, the IPP electricity being priced on the basis of total generating costs of the electric power utilities. Such a price to purchase the electricity of IPPs is referred to as the “break-even cost.” The main results are summarized as follows: 1) Break-even cost depends on not only the power flow constraints in the system, but also various IPP factors such as generating pattern, location, and capacity, 2) Break-even cost for the base-type IPP is higher than the avoided cost of corresponding utility generators, because IPPs located on demand sides can reduce the transmission power loss in the electric power system, 3) Break-even cost is affected by available capacity of utility generators, especially for the peak-type IPP generating only during peak demand periods. © 2000 Scripta Technica, Electr Eng Jpn, 133(2): 20–30, 2000 [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]

Discusses the regional energy saving potential by cascade use of waste heat energy intensive industries in Japan. Heat cascading model; Industrial structure for heat cascading minimizing energy consumption; Influence of local industrial structure on the energy saving potential by heat cascading.

A cryogenic power cable is expected to be capable of carrying bulk power as a main transmission line in a future metropolitan electric power system. It is important to establish a strategy of how to sustain power supply route trips from the network due to contingency. It is proposed here that the bulk power transmitted by the cryogenic cable could be distributed into the parallel conventional transmission lines by suitable circuit breaker operations in the system. In this process, power-flow routes are forced to be changed with a remarkable modification in the system configuration. In this paper, the power swings associated with the large power-flow change following contingent faults are analyzed by means of a transient network analyzer. It is found that the proposed system modification could be realized without any harmful power swing if the parameters in generators as well as in control devices have conventional magnitudes. It is shown also by simulation that the margin to occurrence in an unstable power swing is left sufficient even if the parameters deviated somewhat from the present magnitudes. [ABSTRACT FROM AUTHOR]

The authors have investigated the operational feasibility of a future metropolitan electric power system associated with highly densified cryogenic cables. A new concept of power system configuration with cryogenic cables and its operation have been proposed. Three different models of future power transmission systems in large cities of Japan have been constructed as the background systems prior to introduction of cryogenic cables in the 21st century. This paper considers one of the three models which is characterized by its conventional transmission system constructed mainly by 154-kV transmission lines stepping don directly from the 500-kV outer ring without any intermediate voltage class. This paper also discusses whether or not the power system model will be operated effectively together with cryogenic cables to supply demands forecasted in the period subsequent to the first decade of the 21st century. The computer simulations are carried out to obtain power flow and bus voltage distributions for a peak load period as well as for an off-peak one in the power system model. These simulations reveal that the conventional background power system should be arranged very carefully before introducing the cryogenic cables to facilitate their operations. (1) On a contingent trip of a cryogenic cable in the peak in the peak load period, not all bus voltages are expected to be kept within a tolerant zone due to the high impedance of 154-kV conventional transmission lines in the power system model. (2) Thus it is proposed that the background conventional system prior to introduction of cryogenic cables should be developed not only by extension of 154-kV conventional transmission lines but also by introduction of 275-kV lines. (3) Bus voltage rises induced in the off-peak load period are reduced by effective utilization of 275-kV conventional transmission lines. [ABSTRACT FROM AUTHOR]

We quantitatively investigated the image quality in deep tissue imaging with optical coherence microscopy (OCM) in the 1700 nm spectral band, in terms of the signal-to-background ratio (SBR) and lateral resolution. In this work, to demonstrate the benefits of using the 1700 nm spectral band for OCM imaging of brain samples, we compared the imaging quality of OCM en-face images obtained at the same position by using a hybrid 1300 nm/1700 nm spectral domain (SD) OCM system with shared sample and reference arms. By observing a reflective resolution test target through a 1.5 mm-thick tissue phantom, which had a similar scattering coefficient to brain cortex tissue, we confirmed that 1700 nm OCM achieved an SBR about 6-times higher than 1300 nm OCM, although the lateral resolution of the both OCMs was similarly degraded with the increase of the imaging depth. Finally, we also demonstrated high-contrast deep tissue imaging of a mouse brain at a depth up to 1.8 mm by using high-resolution 1700 nm SD-OCM. [ABSTRACT FROM AUTHOR]

We present three-dimensional (3-D) high-resolution spectral-domain optical coherence microscopy (SD-OCM) by using a supercontinuum (SC) fiber laser source with 300-nm spectral bandwidth (full-width at half-maximum) in the 1700-nm spectral band. By using low-coherence interferometry with SC light and a confocal detection scheme, we realized lateral and axial resolutions of 3.4 and 3.8 μm in tissue (n = 1.38), respectively. This is, to the best of our knowledge, the highest 3-D spatial resolution reported among those of Fourier-domain optical coherence imaging techniques in the 1700-nm spectral band. In our SD-OCM, to enhance the imaging depth, a full-range method was implemented, which suppressed the formation of a coherent ghost image and allowed us to set the zero-delay position inside the samples. We demonstrated the 3-D high-resolution imaging capability of 1700-nm SD-OCM through the measurement of an interference signal from a mirror surface and imaging of a single 200-nm polystyrene bead and a pig thyroid gland. Deep tissue imaging at a depth of up to 1.8 mm was also demonstrated. This is the first demonstration of 3-D high-resolution SD-OCM in the 1700-nm spectral band. [ABSTRACT FROM AUTHOR]

This paper discusses the application of the novel technology - functionally graded material (FGM), which combines both spatial permittivity (ε) and conductivity (σ) distributions with the aim to control the electric field around DC-GIS spacer. Some distribution types of ε and/or σ in the spacer bulk, such as U-type and graded to higher conductivity (GHC) are investigated through electric field simulation, in comparison to the uniform spacer with constant ε and σ distributions. The electric field relaxation effect of each distribution type of ε/σ-FGM under DC steady state, DC polarity reversal, DC-on, and lightning impulse voltage superimposed on DC steady state condition are obtained. The results show that ε/σ-FGM with U-type permittivity and GHC-type conductivity distribution of which low σ is applied near the high voltage side of the DC-GIS spacer is the most effective in reducing the maximum electric field under all stated conditions. [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]

In AC/DC converter transformers under DC application, the electric field distributions are distorted due to the accumulated charge on pressboard. However, the time‐dependent characteristics of DC electric field stress in oil has not yet been clarified in detail. In this paper, we investigated the time and electric field space transition characteristics of DC electric field distributions in oil‐pressboard composite insulation systems. As a result, we quantitatively clarified that DC electric field stress strongly depends on the elapsed time and the location in the electric field space in oil. In particular, it was found that the most severe electric field stress in oil may emerge during the time transition process. [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]

Vacuum interrupter has a composite insulation system. When an internal insulation fails, the discharge has complex and various patterns. Previously, based on the discharge development characteristics, we proposed a discrimination method for the discharge pattern in vacuum interrupter. We measured the applied voltage, anode current, and shield potential waveforms, respectively. From the analysis of the measured waveforms, we can estimate the discharge patterns and discharge path lengths. In this paper, a non-contact shield potential measurement was proposed when the shield potential cannot be measured directly. Furthermore, verification tests with this measurement method were conducted and the effectiveness of the discrimination method was confirmed. [ABSTRACT FROM PUBLISHER]

Key Clinical Message Congestive heart failure caused by secondary hypocortisolism is rare but clinically significant, because its appropriate treatment is effective. Severe hyponatremia with indefinite complaint resembling depression or persisting fever despite antibiotics may be important for establishing this diagnosis. [ABSTRACT FROM AUTHOR]

SUMMARY We investigated the decisive factors that affect partial discharge inception voltage (PDIV) fluctuation between the coil wires under a sinusoidal voltage by using a rectangular wire motor. As a result, we found that PDIV under low humidity fluctuates by the surface charge, and PDIV under high humidity varies transitionally with the surface conductivity activated by predischarge. From these analyses, we proposed the measurement method of PDIV with a low fluctuation and transition for the rectangular wire motors, which will be optimized by environmental humidity, predischarge condition, and measuring frequency. [ABSTRACT FROM AUTHOR]