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This paper proposes a harmonic compensation method using an open-ended winding IPMSM driven by an electrolytic capacitor-less dual inverter in a motor drive system. In the conventional electrolytic capacitor-less single inverter, harmonics caused by the DC-link voltage ripple frequency are superimposed on the motor phase current under a distorted input voltage. As a result, the reliability of the motor drive system is reduced, and the torque ripple causes mechanical vibration and noise. Using the proposed control method, the compensating inverter outputs the harmonic voltage superimposed on the estimated motor winding voltages. The experimental results show that compared to the conventional electrolytic capacitor-less single inverter, the proposed system reduces the maximum peak-to-peak of motor current by 8 %, and the shaft torque ripple caused by a distorted input voltage by 75 %. For motor drive systems without energy buffer that are driven under a distorted grid voltage, the proposed control method improves reliability and reduces mechanical vibration and noise.

An electrolytic capacitor-less single inverters do not have an energy buffer, so the distorted grid voltage causes harmonics to be superimposed on the motor current. The harmonics reduce the reliability of the motor drive system due to the increased the motor peak current and the peak torque. This paper proposes a harmonic compensation method for an electrolytic capacitor-less inverter using a dual inverter to improve the reliability of a motor drive system under a periodical torque fluctuation load condition. In the proposed system, the compensation inverter compensates by estimating the harmonics superimposed on the motor winding voltage without being affected by the interference with the vibration suppression control method during periodical load torque fluctuations, and thus improves the reliability of the system. The experimental results show that the proposed system reduces the harmonic of motor current by 79 %, and the peak-to-peak of torque by 9 % compared with the conventional electrolytic capacitor-less single inverter.

The switching operation of a Cu/MoOx/TiN resistive random access memory (ReRAM) device was investigated using in situ transmission electron microscopy (TEM), where the TiN surface was slightly oxidized (ox-TiN). The relationship between the switching properties and the dynamics of the ReRAM microstructure was confirmed experimentally. The growth and/or shrinkage of the conductive filament (CF) can be classified into two set modes and two reset modes. These switching modes depend on the device's switching history, factors such as the amount of Cu inclusions in the MoOx layer and the CF geometry. High currents are needed to produce an observable change in the CF. However, sharp and stable switching behaviour can be achieved without requiring such a major change. The local region around the CF is thought to contribute to the ReRAM switching process.

For dynamical observation of CBRAM microstructure, in situ transmission electron microscopy (in situ TEM) was performed on Cu/MoOx/TiN during the resistive switching. It was confirmed that the local area near the MoOx/TiN interface contributes to resistive switching. The Cu deposit at the bottom of the MoOx layer swelled into the oxidized thin layer of the TiN bottom electrode, and a thin filament of 3–5 nm diameter was formed in the Set process. The reversal change was seen in the Reset process. On increasing the switching power, a microstructural change in the MoOx layer was also seen, and the CBRAM film was finally destroyed.

In-situ TEM observation was applied to a miniaturized Cu / MoOx / TiN ReRAM device shaped by the ion-shadow method. Applying a positive voltage to the Cu top electrode, resistive switching from the high-resistance state (HRS) to the low-resistance state (LRS) occurred, and a precipitation appeared in the switching layer of MoOx. On the other hand, negative voltage to Cu erased the precipitation, and the resistance state was converted from LRS to HRS. Growth or contraction of the precipitation was recognized during further voltage application after the switching operation. The precipitation observed in this work is thought to correlate with the resistive switching, and its formation and rupture phenomenon agrees to the switching mechanism based on conductive filaments.

The ion-shadow method, an ion milling process using carbon particles as the mask material, is investigated as a means of preparing resistance random access memory (ReRAM) samples for in situ transmission electron microscopy (TEM). With a milling time of 1 hour (Ar+, 5 kV, 1 mA), multiple long needles (> 5 μm), on which there are miniaturized ReRAM devices comprising a ReRAM insulating layer sandwiched by two metallic electrodes, are formed on the substrate. Device sizes of up to several hundreds of nm are easily obtained with the method. The internal part of small devices (i.e., up to 100 nm) can be observed by TEM. Electrical measurements using an in situ TEM holder demonstrate that sufficient electric contact is obtained without any electric shortage between the electrodes due to re-deposition of milled material. The ion-shadow method is confirmed to be a quick and easy method suitable for in situ TEM experiments, especially for ReRAM devices which are highly susceptible to destruction during the switching operation.

Most patients with tuberous sclerosis complex (TSC), an autosomal-dominant disorder that is caused by the constitutive activation of mammalian target of rapamycin, experience disfigurement caused by skin lesions involving facial angiofibromas. Many have been left untreated because of a lack of therapeutic options that are less invasive than surgery or laser treatment.To confirm the efficacy and safety of sirolimus gel, 0.2%, for treatment of patients with angiofibromas and/or skin lesions.Multicenter, randomized clinical trial at 9 centers in Japan from December 2015 to October 2016 including 62 children and adults with TSC.Patients who developed angiofibromas were randomly assigned, in a 1:1 ratio, to receive sirolimus gel, 0.2%, or placebo, each applied topically twice daily for 12 weeks.The primary end point was composite improvement in the size and color of angiofibromas in photographs at week 12 of treatment. It was assessed by an independent review committee comprising 3 blinded dermatologists who categorized patient results into the following 6 categories: "markedly improved," "improved," "slightly improved," "unchanged," "slightly aggravated," and "aggravated."Sixty-two patients (27 pediatric and 35 adult; 34 [55%] female; mean [SD] age, 22.5 [11.9] years) were enrolled and randomly assigned to receive sirolimus gel, 0.2% (30 patients), or placebo (32 patients). The response rates of angiofibromas at weeks 4, 8, and 12 of treatment were 0 each in the placebo group in contrast to 20% (95% CI, 8%-39%; P = .01), 43% (95% CI, 26%-63%; P .001), and 60% (95% CI, 41%-77%; P .001), respectively, in the sirolimus group. None of the 31 assessable patients in the placebo group were rated improved or better, and 26 of them (84%) were rated unchanged. In contrast, 5 (17%) and 13 (43%) patients in the sirolimus group were rated markedly improved and improved, respectively. Adverse events were mild to moderate and were observed in 27 (90%) and 22 (69%) patients in the sirolimus and placebo groups, respectively; however, none of the trial participants discontinued treatment. Acute pancreatitis developed as a serious adverse event in 1 patient in the sirolimus group, and the patient recovered soon after hospitalization without discontinuing treatment.Sirolimus gel, 0.2%, demonstrated a significant clinical benefit for patients with TSC involving angiofibromas, thus providing a promising therapeutic modality.ClinicalTrials.gov Identifier: NCT02635789.

In-situ transmission electron microscopy (in-situ TEM) was performed to investigate the switching operation of a resistive random access memory (ReRAM) made of copper, tungsten oxide and titanium nitride (Cu/WOx/TiN). In the first Set (Forming) operation to initialize the device, precipitation appeared inside the WOx layer. It was presumed that a Cu conducting filament was formed, lowering the resistance (on-state). The Reset operation induced a higher resistance (the off-state). No change in the microstructure was identified in the TEM images. Only when an additional Reset current was applied after switching to the off-state could erasure of the filament be seen (over-Reset). Therefore, it was concluded that structural change relating to the resistance switch was localized in a very small area around the filament. With repeated switching operations and increasing operational current, the WOx/electrode interfaces became indistinct. At the same time, the resistance of the off-state gradually decreased. This is thought to be caused by Cu condensation at the interfaces because of leakage current through the area other than through the filament. This will lead to device degradation through mechanisms such as endurance failure. This is the first accelerated aging test of ReRAM achieved using in-situ TEM.

Inner-structural changes of a Cu/MoOx ReRAM was observed by in-situ TEM during the resistive switching. We succeeded for the first time to observe the structure changes in the continuous multiple resistive switching cycles. Cu-rich filament was formed in the MoOx layer during the SET process with positive voltage to the Cu electrode, and disappeared by negative voltage in the RESET process. It was also confirmed that thick filaments were generated when the current compliance for the SET process was increased. The most meaningful phenomenon is that the position of the filament changed at each SET process.

In-situ filament observations were carried out on the Cu/MoOx/TiN resistive random access memory (ReRAM) by using transmission electron microscopy. Multiple positive and negative I-V cycles were investigated. Clear set-reset bipolar switch corresponding to the characteristics of conventional ReRAM devices was recognized. Filament grew from TiN to Cu in the set cycle and shrank from TiN to Cu in the reset cycle. However, there was no clear contrast change in the image at the switching moment, and thus, switching is thought to occur in a local region of the filament. When the current was large at reset, the filament shrank much, and its position tended to change.

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4-Aryl-1-tritylpyrazoles were prepared from the cross coupling reaction of aryl Grignard reagents with 4-bromo-l-tritylpyrazoles in the presence of 0.2 mol% PdCl 2 (dppf) as catalyst. To deprotect the trityl group, 4-phenyl-l-tritylpyrazole was reacted with TFA to produce 4-arylpyrazole in quantitative yield.