Current Lead Research Articles

First demonstration of a novel nerve-targeting fluorophore in a cohort of ex vivo human tissues.

Iatrogenic nerve injury is a common complication across all surgical specialties. Better nerve visualization and identification during surgery will improve outcomes and reduce nerve injuries. The Gibbs Laboratory at Oregon Health and Science University has developed a library of near-infrared, nerve-specific fluorophores to highlight nerves intraoperatively and aid surgeons in nerve identification and visualization; the current lead agent is LGW16-03. Prior to this study, testing of LGW16-03 was restricted to animal models; therefore, it was unknown how LGW16-03 performs in human tissue. To advance LGW16-03 to clinic, we sought to test this current lead agent in ex vivo human tissues from a cohort of patients and determine if the route of administration affects LGW16-03 fluorescence contrast between nerves and adjacent background tissues (muscle and adipose). LGW16-03 was applied to ex vivo human tissue from lower limb amputations via two strategies: (1) systemic administration of the fluorophore using our first-in-kind model for fluorophore testing, and (2) topical application of the fluorophore. Results showed no statistical difference between topical and systemic administration. However, in vivo human validation of these findings is required.

Design and Implementation of the Linear LED Driver

This brief presents a new LED control scheme to maintain a constant LED power. In LED control schemes, the conventional approach is to maintain a constant LED current. However, this traditional approach will bring high power at high input voltage and then generate high heat. The higher heat will shorten the life time of the product and reduce the reliability. The proposed scheme can solve this problem. The LED driver with the proposed scheme has been successfully fabricated by Macronix and the feasibility of the method has been verified. From the experimental results, the higher the input voltage, the lower the LED current. This constant power method can effectively avoid overheating at high input voltage. The control scheme, the theoretical analysis and the circuit implementation are presented in this brief.

Electromagnetic design and temperature field analysis of hybrid excitation primary permanent magnet linear motor

Hybrid excitation primary permanent magnet linear motor has the dual advantages of high thrust density of primary permanent magnet linear motor and the flexibility on adjusting the air gap magnetic field of hybrid excitation motor. In this paper, two new 36/4 hybrid excitation primary permanent magnet linear motors with different secondary structures are proposed. Based on the detailed introduction of the motor topology and operation mechanism, the structural parameters are optimized, and the pole arc coefficient of the primary pole shoe and the secondary are finally determined to be 0.4. The secondary is magnetoresistive, and the final thrust adjustment range is about 16.8% under the conditions of optimal armature current and current lead angle. The temperature field of the motor in the magnetizing state is analyzed. The results show that the temperature of the motor decreases gradually from the center to both sides after 7200 s of operation of the new hybrid excitation structure, while the permanent magnet will not be demagnetized permanently. It shows an acceptable reliability.

Reducing Low-Frequency Ripple Using Alternative Output Capacitor Connection on Integrated Converters for LED Drivers

Although advantageous in several aspects, the integration of converters leads to a loss of independence between the converter's stages, since both stages are controlled by the same active switch. This condition makes it impractical to adopt control techniques that act on the duty-cycle to mitigate the low-frequency ripple at the output current without distorting the line current. The low-frequency ripple transferred from the bus voltage to the LED current has been studied for integrated converters operated at constant duty-cycle. To comply with IEEE 1789-2015 recommendation, the integrated converters use large capacitors to mitigate the low-frequency ripple. Converters operating in discontinuous conduction mode (DCM) have been widely adopted because they transfer less ripple to the output than converters operating in continuous conduction mode (CCM). A novel circuit arrangement for the buck-boost power control (PC) stage integrated with a buck-boost power factor correction (PFC) stage is explored in this paper as a technique to minimize the low-frequency output ripple for converters operating at constant duty-cycle and CCM. The proposed circuit provides current feedback to the bus capacitor, acting to reduce the output current and bus voltage low-frequency ripple. A dynamic model for the proposed converter in CCM is obtained and used to determine the output current modulation as a function of converter parameters. It is shown that the proposed topology leads to a smaller low-frequency ripple than a conventional counterpart at the same operating point. A 95 W design example and a prototype supplying an LED load of 98.8 V / 960 mA for the proposed circuit and the conventional counterpart are presented. The experimental results show that the proposed arrangement can achieve similar results to the conventional circuit in efficiency, THD, or semiconductor stress, while the obtained output current modulation equals to 8.66 % is 3.5 times lower than that in the conventional circuit at same operating point and component values.

Eliminating the Need for a Less Strict Requirement for the Negative-Sequence LVRT Current of Type-III Wind Turbine Generators in the IEEE 2800 Standard

Similar to emerging regional grid codes, the recently approved IEEE 2800 Standard mandates that inverter-based resources (IBRs) generate negative-sequence current during low-voltage ride-through (LVRT) conditions. The 2800 Standard requires that the IBRs' negative-sequence current lead the negative-sequence voltage by 90 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ$</tex-math></inline-formula> –100 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ$</tex-math></inline-formula> to emulate synchronous generators and reduce the likelihood of protection malfunction. However, the limitations of existing doubly-fed induction generators (DFIGs) led the Standard to exempt the DFIGs from this requirement and allow a wider range for their negative-sequence current angle. Meanwhile, the 2800 Standard also acknowledged that this exemption had unidentified and potentially negative impacts on protective relays. This paper (i) sheds light on several so-far-unknown DFIG characteristics that impact the angle of the negative-sequence current during LVRT, (ii) reveals the impacts of the above DFIG exemption on relays, and (iii) develops a solution to prevent the need for this exemption in the future revisions of the IEEE 2800 Standard.

A Rapid Prototyping Method for Sub-MHz Single-Element Piezoelectric Transducers by Using 3D-Printed Components.

We present a rapid prototyping method for sub-megahertz single-element piezoelectric transducers by using 3D-printed components. In most of the early research phases of applying new sonication ideas, the prototyping quickness is prioritized over the final packaging quality, since the quickness of preliminary demonstration is crucial for promptly determining specific aims and feasible research approaches. We aim to develop a rapid prototyping method for functional ultrasonic transducers to overcome the current long lead time (>a few weeks). Here, we used 3D-printed external housing parts considering a single matching layer and either air backing or epoxy-composite backing (acoustic impedance > 5 MRayl). By molding a single matching layer on the top surface of a piezoceramic in a 3D-printed housing, an entire packaging time was significantly reduced (<26 h) compared to the conventional methods with grinding, stacking, and bonding. We demonstrated this prototyping method for 590-kHz single-element, rectangular-aperture transducers for moderate pressure amplitudes (mechanical index > 1) at focus with temporal pulse controllability (maximum amplitude by <5-cycle burst). We adopted an air-backing design (Type A) for efficient pressure outputs, and bandwidth improvement was tested by a tungsten-composite-backing (Type B) design. The acoustic characterization results showed that the type A prototype provided 3.3 kPa/Vpp far-field transmitting sensitivity with 25.3% fractional bandwidth whereas the type B transducer showed 2.1 kPa/Vpp transmitting sensitivity with 43.3% fractional bandwidth. As this method provided discernable quickness and cost efficiency, this detailed rapid prototyping guideline can be useful for early-phase sonication projects, such as multi-element therapeutic ultrasound array and micro/nanomedicine testing benchtop device prototyping.

Sc2Mol: a scaffold-based two-step molecule generator with variational autoencoder and transformer.

Finding molecules with desired pharmaceutical properties is crucial in drug discovery. Generative models can be an efficient tool to find desired molecules through the distribution learned by the model to approximate given training data. Existing generative models (i) do not consider backbone structures (scaffolds), resulting in inefficiency or (ii) need prior patterns for scaffolds, causing bias. Scaffolds are reasonable to use, and it is imperative to design a generative model without any prior scaffold patterns. We propose a generative model-based molecule generator, Sc2Mol, without any prior scaffold patterns. Sc2Mol uses SMILES strings for molecules. It consists of two steps: scaffold generation and scaffold decoration, which are carried out by a variational autoencoder and a transformer, respectively. The two steps are powerful for implementing random molecule generation and scaffold optimization. Our empirical evaluation using drug-like molecule datasets confirmed the success of our model in distribution learning and molecule optimization. Also, our model could automatically learn the rules to transform coarse scaffolds into sophisticated drug candidates. These rules were consistent with those for current lead optimization. The code is available at https://github.com/zhiruiliao/Sc2Mol. Supplementary data are available at Bioinformatics online.

Structure, design, and test of 13 kA HTS current lead

The 13 kA High Temperature Superconducting Current Leads (HTSCL) were designed and manufactured by the Institute of plasma physics, Chinese Academy of Sciences (ASIPP). This lead differs from former HTS current leads, in that it features an integrated heat exchanger (HEX) structure, a HTS magnetic shield and protective sleeve, and a Low Temperature Superconducting (LTS) module with a through cold conduction channel. The HTS and LTS module is cooled by SHe. In November 2020, the 13 kA steady-state test, Loss Of Flow Accident (LOFA) test, joint resistance test, pulse current test, insulation voltage test and other low-temperature electrical test items of the leads were completed. The test results indicate that all parameters meet the design requirements.

Merging Passivation in Synthesis Enabling the Lowest Open-Circuit Voltage Loss for PbS Quantum Dot Solar Cells.

The high open-circuit voltage (Voc ) loss arising from insufficient surface passivation is the main factor that limits the efficiency of current lead sulfide colloidal quantum dots (PbS CQDs) solar cell. Here, synergistic passivation is performed in the direct synthesis of conductive PbS CQD inks by introducing multifunctional ligands to well coordinate the complicated CQDs surface with the thermodynamically optimal configuration. The improved passivation effect is intactly delivered to the final photovoltaic device, leading to an order lower surface trap density and beneficial doping behavior compared to the control sample. The obtained CQD inks show the highest photoluminescence quantum yield (PLQY) of 24% for all photovoltaic PbS CQD inks, which is more than twice the reported average PLQY value of ≈10%. As a result, a high Voc of 0.71V and power conversion efficiency (PCE) of 13.3% is achieved, which results in the lowest Voc loss (0.35eV) for the reported PbS CQD solar cells with PCE >10%, comparable to that of perovskite solar cells. This work provides valuable insights into the future CQDs passivation strategies and also demonstrates the great potential for the direct-synthesis protocol of PbS CQDs.

Design Optimization of an Efficient Bicolor LED Driving System

There are some challenges involved in the design of a multicolor LED driver, such as the precise control of color consistency, i.e., maintaining the correlated color temperature (CCT) and luminous intensity. CCT deviation causes a color shift of composite light. This paper approaches the method of nonlinear optimization of the LED currents of two LED sources to achieve the desired CCT. A bicolor blended-shade white LED system is formed by using a warm color LED source of 1000 K CCT and a cool color LED source of 6500 K CCT. By using a nonlinear optimization methodology, the reduced deviation of the blended CCT and optimum LED currents are obtained. The optimized currents in the two LED strings are maintained by the control circuit of the single-ended primary inductor converter (SEPIC). The obtained reduced deviation of the CCT is 43 K, and the precision is 99.15%. Again, harmonics in the input current hamper power quality, i.e., reduce the power factor and increase power loss. This paper proposes the harmonic reduction technique to achieve the lowest value of total harmonic distortion (THD) through the nonlinear parametric optimization of the SEPIC. Measured THD = 4.37%; PF = 0.96; and efficiency = 92.8%. The system stability was determined and found to be satisfactory.

THE INFLUENCE OF THE ANODE MATERIAL ON THE COURSE OF COMBINED PROCESSES DURING THE REGENERATION OF SULPHATE-ACID SOLUTIONS

The existing methods of regeneration of sulfo-acidic solutions, which contain iron sulfate, formed after technological operations for the preparation and etching of metal parts at metalworking enterprises are not effective and therefore are not used at Ukrainian enterprises. They are either aimed at sedimentation of the sludge of sparingly soluble iron compounds after neutralization of unreacted sulfuric acid or at dilution of the formed spent sulfo-acid solutions. The electrochemical method of regeneration of such spent sulfo-acid solutions is not properly researched. A feature of the development of technology and equipment for regeneration is a decrease in the content of iron ions and an increase in the concentration of sulfuric acid during the regeneration process. The process of electrochemical regeneration of spent steel etching solutions is characterized by a significant change in the composition of the etching solution and the temperature of the etching process. At the beginning of work, the initial solution of sulfuric acid reaches a concentration of 2.0 mol·dm-3 and does not contain iron (II) sulfate. In the process of digestion, the concentration of sulfuric acid decreases to 0.5 mol·dm-3, and the concentration of iron (II) sulfate increases accordingly. Therefore, the course of the anodic process was studied for the following solution compositions: 0.5 mol·dm-3; 1.0 mol·dm-3 and 1.5 mol·dm-3 H2SO4. Under the conditions of a decrease in the concentration of sulfuric acid, its chemical activity also decreases when interacting with iron oxides and hydroxides. An increase in the temperature of the entire process is used to increase the reactivity of the pickling solutions. The main process at the platinum anode is the release of oxygen in a wide range of current densities and a significant overvoltage of the entire process. Taking into account the obtained voltage-voltage dependences, it can be seen that the current rises when reaching potentials that significantly exceed the standard potential for obtaining oxygen from water. The advantage of the platinum anode is the slight influence of the concentration of sulfuric acid on the kinetics of the anode process. The obtained results were used for comparison with other alternative anode materials. Manganese dioxide was obtained by the method of pyrolysis of a coating solution of manganese monoacid applied to a titanium current lead, which can be represented by reaction (5) of the decomposition of manganese nitrate on a titanium plate. Due to the developed surface, the real current density was more than an order of magnitude lower on the TDMA than on the platinum anode with the same geometric dimensions. A lower current density contributed to a decrease in the steady-state potentials of oxygen release. The current density can be increased by an order of magnitude if surfactants are added to the working solution. A comparison of voltage-voltage dependences on platinum and TDMA indicates that the use of TDMA gives a more significant gain in energy consumption during the regeneration process. Taking into account that the range of current densities of 4-5 A/dm2 was determined for the cathode process according to the research results, the difference in the reduced polarization of the anode on TDMA, compared to platinum, is more than 400 mV, which will significantly reduce costs during unit operation. The use of TDMA is expedient in the galvanostatic mode of operation of the electrode unit for the process of electrochemical regeneration of spent sulfo-acid solutions of steel pickling.

Improving the Efficacy of Quinolylnitrones for Ischemic Stroke Therapy, QN4 and QN15 as New Neuroprotective Agents after Oxygen-Glucose Deprivation/Reoxygenation-Induced Neuronal Injury.

In our search for new neuroprotective agents for stroke therapy to improve the pharmacological profile of the compound quinolylnitrone QN23, we have prepared and studied sixteen new, related and easily available quinolylnitrones. As a result, we have identified compounds QN4 and QN15 as promising candidates showing high neuroprotection power in a cellular experimental model of ischemia. Even though they were found to be less active than our current lead compound QN23, QN4 and QN15 provide an improved potency and, particularly for QN4, an expanded range of tolerability and improved solubility compared to the parent compound. A computational DFT-based analysis has been carried out to understand the antioxidant power of quinolylnitrones QN23, QN4 and QN15. Altogether, these results show that subtle, simple modifications of the quinolylnitrone scaffold are tolerated, providing high neuroprotective activity and optimization of the pharmacological potency required for an improved design and future drug developments in the field.

RF04 | PSUN295 Evolution of Monomeric Multi-Agonists of GLP-1 and NPY Receptors

Abstract Current treatments for type 2 diabetes (T2D) and obesity do not reliably achieve long-term weight-loss and up to 50% of patients experience nausea and vomiting. Thus, there is a critical need for obesity medications that provide glycemic control with enhanced hypophagic response without nausea/emesis. Based on rational design and in silico modelling of the glucagon-like peptide 1-receptor agonist (GLP1RA) exendin-4 (Ex4) and the neuropeptide Y2 receptor (Y2R) agonist peptide YY (PYY) 3-36, we have developed and screeened several new monomeric chimeric peptides that display dual agonism of the anorectic Y2R and the glucoregulatory GLP1R. In addition, we explored a third agonistic behavior at the neuropeptide Y1 receptor (Y1R), which potentially relates to pancreatic beta-cell protection. Our current lead, GEP44, binds the Y2R, Y1R, and GLP1R. We tested effects of daily injections of these chimeric peptides in adult Sprague-Dawley rats on food intake (FI), body weight (BW) changes, blood glucose levels and an indicator of nausea (kaolin intake). GEP44 produced profound reduction in FI (2-d average GEP44 at 20 nmol/kg FI -71%; Ex-4 20 nmol/kg FI -40%). Anorectic doses of GEP44 did not trigger a pica response assessed by kaolin consumption in treated rats, while in Ex-4 treated rats, kaolin consumption accounted for 28% of total daily solid intake, indicating a clear nausea response. In addition, we assayed for emetic response in the musk shrew, with little to no such emesis displayed (n=8) for GEP44 (1/8), but emesis noted across all animals tested for Ex4. During 11 d of treatment with GEP44, FI was consistently reduced resulting in a significantly stronger reduction of BW compared to Ex4 at the end of treatment (GEP44 -7.6%, Ex4 -3.7%, p&amp;lt;0.05). Furthermore, 5-day injections of GEP44 showed greater reduction of glucose levels than for Ex4 in diet induced obese rats receiving ip glucose. In conclusion, simultaneously targeting serial anorectic pathways with single molecule chimeric peptides can address multiple coexisting conditions to more efficaciously reduce FI, BW and blood glucose levels, devoid of side-effects to improve patient patient and quality of life. Presentation: Saturday, June 11, 2022 1:00 p.m. - 1:05 p.m., Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.

S3.4c A pipeline toward the identification of novel antifungal compounds derived from the microbial dark matter

S3.4 Free oral paper session, September 21, 2022, 4:45 PM - 6:15 PMBackgroundThe current armamentarium of antifungal drugs and the restricted variety in antifungal drug classes combined with the ever-rising threat of resistant fungal pathogens highlighted the urgent need for novel antifungal compounds. Natural antifungal secondary metabolites have always been the prevalent source for drug development, exemplified by the echinocandin and polyene drug classes. Yet, the golden age discovery platforms were abandoned due to compound rediscovery and its paired economic cost.StudyIn an effort to revive the original success stories, we combined the traditional approach of sampling and screening for active secondary metabolites with present-day advances in sequencing, genome mining, impedance spectroscopy, HPLC, LCMS, and NMR.Soil bacteria and fungi were isolated through in situ cultivation via the iChip method. After application of the OSMAC approach, 389 broths were identified with activity against Candida albicans. To prioritize active extracts, several criteria were set up; low to absent mammalian host cell toxicity, activity against a broad spectrum of fungal pathogens including wild-type reference strains, and established antifungal drug-resistant variants and species identification of the producing strain. Continuing, Lead hits were purified utilizing bioactivity-based semi-preparative HPLC. The resulting pure fractions were analyzed by tandem LCMS-MS, and proposed structures were later confirmed with NMR. In vitro and in vivo validation of the purified compounds will be performed.Additionally, aside from discovering a novel antifungal compound, another project goal is to gauge if impedance spectroscopy can provide an early suggestion regarding the mode of action of the present antifungal agent. For this, a POC study was performed which showed that different antifungal drug classes provide distinct signature response profiles by which they can be classified. As such, when active secretion broths show unique impedance profiles, in comparison with the signature profiles of established antifungal drugs, it suggests that they work through a different mode of action.ResultsSeveral species were identified as producing antifungal secondary metabolites that are currently absent in the literature. Either the compound itself was unknown or literature never described the species as a producer of a known, or variant of a known antimycotic compound. Moreover, several species are novel based on Illumina sequencing. Genera producing our current lead hits include bacteria: Pseudomonas, Tsukamurella, Paraburkholderia, and fungi: Athelia, Penicillium. Within the collection, the Pseudomonas species appear to produce variants of the antimycotic iron-chelating pyoverdine class.

Finite element analysis of the temperature distribution within a Conduction-Cooled, MgB2-based MRI superconducting coil segment

Superconducting magnets used for Magnetic Resonance Imaging (MRI) scanners need to keep temperature gradients minimized in order to retain thermal and operating current margin. We have used 3D finite element analysis (FEA) simulation in COMSOL Multiphysics software that includes both conductive heat transfer and radiative heating to calculate the temperature distribution both along the winding direction and across the cross-section of an MRI segment coil at its equilibrium operating temperature. We have also modelled the evolution of the thermal properties during cool-down from ambient temperature. The heat capacity and thermal conductivity of the magnet winding were computed for use within this simulation. The heat capacity as a function of temperature was calculated using a rule of mixtures. This procedure was also used for the thermal conductivity along the direction of the wire. However, the thermal conductivity within the composite cross section (x- and y-directions) was computed using a 2D FEA model. Based on this, a time-dependent, 3D coil model was built to calculate the coil temperature throughout the winding during cool-down in our test cryostat system. The model included a heat leak component to the coil current contacts via conduction through the current leads as well as a radiative component from the surfaces of the cryostat. A key result was that a maximum coil ΔTmax = 5.1 K (=maximum temperature within the winding -minimum temperature in the winding) was seen and a coil Ic margin of 12.75 A was predicted at steady state, with our first current lead design. A second set of more optimized current leads significantly lowered the ΔTmax within the coil at the steady state. The coil Ic margin has been analyzed for different current lead designs.

Investigating Structural, Thermal and Optical Properties of Lead Oxide Nano-Particles Synthesized by Sol-Gel Combustion Method

Metal and metal oxide nanoparticles (NPs) have piqued the interest of material scientists in recent years due to their unique physicochemical properties which are dependent on their size, shape, and chemical surroundings. The sol gel combustion is one of the most straightforward and practical technique for getting tiny and similar size and shape of the powder out of all the current lead oxide nanoparticle synthesis techniques. In this study, PbO nanoparticles are prepared using the sol-gel method followed by an auto combustion process. This research is aimed at the particle size, shape, thermal analysis, and optical properties of nanostructured PbO. Several microscopic, spectroscopic, and thermogravimetric analysis are employed for the structural characterization of lead oxide nanoparticles. Tiny lead oxide particles with a diameter of 60 nanometres have been prepared. The prepares sample’s optical band gap was discovered to be 2.44 electronvolt. Thermal investigations indicate the thermal behaviour and stability of synthesized lead oxide powder and are described in details.

Gas-Cooled Peltier Current Leads for Compact HTS Devices

As is known, heat losses through current leads essentially determine the economic efficiency of the superconducting systems. Much attention is paid to the design of optimal current leads, but the Wiedemann-Franz law physically limits the benefits of the standard approach. An innovative way to further reduce heat inflow is to use current leads equipped with Peltier thermoelectric elements. These elements are installed in series in the power circuit. Therefore, when the transport current passes through the Peltier element, the thermoelectric effect counteracts the heat flow caused by the temperature gradient in the current lead. Another advantage of this design is that when the circuit is de-energized, the heat loss is reduced due to the low thermal conductivity of the Peltier element. In addition to the theoretical works devoted to the Peltier current leads (PCLs), many experiments confirmed a decrease in heat loss by about 30%. Moreover, PCLs were installed on 500- and 1000-meter HTS power transmission lines in Ishikari (Hokkaido, Japan). An advanced approach involves cooling the current-carrying parts with evaporating nitrogen, which should improve the performance of PCLs. In this work, an experiment on testing gas-cooled PCLs was carried out for the first time. A 30% additional reduction in heat inflow was achieved. At the same time, the dependence of the specific heat loss on the current became flatter, which means an expansion of the range of operating current. In the experiment, the vented gas passed through copper pipes used as conductors. In the future, to increase the efficiency of the gas-cooled PCLs, we plan to improve the heat transfer between the gas flow and the conductor using surface ribbing.

Investigation of Transient Response Caused by Power Supply on JT-60SA Central Solenoid

The JT-60SA power supply of the central solenoid (CS) module contains multiple frequency components, and the transient response phenomenon and the resonance phenomenon cause the voltage non-uniformity in the CS. There is thus a possibility that a local voltage between the conductors that is larger than the withstand voltage of the insulation between conductors will be occurred, and the insulation is damaged. Therefore, an estimation of the transient response phenomenon and the resonance phenomenon is important for verifying that the CS is electrically stable. In the present study, the power supply voltage of the JT-60SA CS module was measured, and the effect of the transient response and the resonance phenomenon on the voltage between CS conductors was evaluated using an analysis model that included CS (four modules), the current lead between the power supply and the CS, and the structures surrounding the CS. The simulation results show that when the actual power supply is applied to the CS, the maximum voltage between CS conductors affected by the transient response and the resonance phenomenon is lower than the withstand voltage of the insulation between CS conductors. The results of our analyses provide fundamental data that can be used to estimate the voltage distribution in the CS and thus ensure the electrical stability.

Construction Status of the Superconducting Magnet System for the COMET Experiment

The COMET experiment, which is being prepared at the Japan Proton Accelerator Research Complex (J-PARC), aims to explore the rare decay phenomenon of muons. This phenomenon is not allowed in the Standard Model of elementary particles but is expected to occur due to new physics beyond the Standard Model. In the COMET experiment, superconducting magnets are used throughout the muon beamline. The Pion Capture Solenoid concentrates the pions generated by the injection of proton beams into the target. Since this magnet surrounds the target, it is designed to operate in a high radiation environment. The Muon Transport Solenoid guides the muons generated by the decay of pions. This magnet maximizes the muon yield and reduces the other background particles. The Detector Solenoid acts as a spectrometer of the electrons generated by the decay of muons. These low-temperature superconducting magnets are now being developed and constructed. The current lead box is also constructed to supply high currents to the magnets. It provides a thermal gradient from the room-temperature part of the power supply to the low-temperature part of the coil. It is designed to provide a large thermal gradient over a short distance using high-temperature superconductors. Using the current lead box, all magnets, including the high-temperature superconducting leads, are cooled by conduction cooling. In this paper, the construction status of the COMET superconducting magnet system is reported.

A Wide-Input-Range Low-Profile Adaptive Delay Compensated Hysteretic LED Driver With Enhanced Current Accuracy

This article presents a wide-input-range low-profile dc–dc-based LED driver. An adaptive delay compensated hysteretic control (ADCHC) is proposed to adaptively modulate both peak and valley inductor currents for minimizing their current deviations, thereby enhancing the accuracy of the average LED current under different input and output voltages. A high-voltage current sensor with passive ripple filtering scheme is also developed to ensure fast and accurate inductor current sensing in the megahertz (MHz) range. The proposed LED driver was realized using two 100-V e-mode GaN FETs as power switches together with on-chip gate drivers and controller implemented in a 0.5- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> , 120-V process. This driver supports an input voltage range from 5 to 100 V and delivers a maximum output power of 25 W. The LED current error is minimized to within ±3.2% of the nominal 350-mA LED current under different input voltages and numbers of output LEDs. Compared with the prior art, the proposed LED driver has the smallest LED current error, operates 2 times higher frequency, and uses <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5\times $ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5.5\times $ </tex-math></inline-formula> smaller inductance and inductor volume. The proposed LED driver also features competitive peak power efficiency of 91.7% at 1.8-MHz frequency and 90-V input.