Radiation Effects of Proton Particles in Memory Devices

In this letter, we study the impact of single event upsets (SEUs) in space or defense electronic systems which use memory devices such as EEPROM, and SRAM. We built a microcontroller test board to measure the effects of protons on electronic devices at various radiation levels. We tested radiation hardening at beam current, and energy levels, measured the phenomenon of SEUs, and addressed possible reasons for SEUs.     

In vitro immunosuppressive activity, isolation from pig liver microsomes and identification by electrospray ms-ms of a new FK-506 C19-C20 epoxide metabolite

In order to mediate their effects, cyclosporin A and FK-506 must each bind with high affinity to a cytosolic target protein that belongs to the immunophilin group. FK-506 forms complexes with the FK-506 binding protein FKBP, mainly FKBP-12, and these complexes possess immunosuppressive activity through their ability to interact with another target, the abundant serine threonine phosphatase calcineurin. Evaluating the immunosuppressive activities of the FK-506 metabolites by comparing them with known immunosuppressive agents via mixed lymphocyte reaction is of clinical importance because some metabolites may retain the pharmacological activity of the parent drug or exhibit cytotoxic effects. FK-506 is metabolized by the cytochrome P-450-dependent mixed-function oxygenase system in different animal species, and we are reporting the isolation from pig liver microsomes, and the identification by electrospray ms-ms, of the FK-506 C19-C20 epoxide metabolite. We found that this new metabolite exhibits reduced in vitro immunosuppressive activity compared with FK-506 and has approximately the same immunosuppressive potency as other known immunosuppressive drugs, such as cyclosporin A and IMM-125, a hydroxyethyl derivative of D-serine cyclosporin A. We were able to demonstrate that after incubation of the FK-506 metabolite in human mixed lymphocyte reaction cultures for 6 days, the compound was stable under the conditions used for cell culture as evidenced by electrospray-ms data. A weak direct cytotoxic effect (< 30% cell death) was observed only at the highest concentrations (2500 and 5000 ng/ml), which shows that the mixed lymphocyte reaction inhibition cannot be due to a toxic effect.     

Optimizing Factors on High Concentration of Ozone Production with Dielectric Barrier Discharge

The gap distance, electrode material, voltage and gas flow velocity were optimized with gas pressure variation of dielectric barrier discharge (DBD) for producing high concentration of ozone. There exists an optimum gas pressure at which the highest ozone concentration is produced with other parameters being fixed. This optimum gas pressure value changes accordingly as the other parameters changed. As the discharge continues at the optimum pressure, the ozone concentration could increase or decrease slowly. This aging effect has different characteristics with the metal electrode material and the impurity level of the oxygen gas used for ozone generation. The aging effect is supposed to be related with the catalytic effect of metal oxide, which is generated in the discharge zone. The change in the characteristic of optimum pressure by the other parameters, indicate that the ozone concentration is deeply related with the filament self-organization characteristics of DBD. At the final optimized condition, the ozone concentration was higher than 22.5 wt.%.     

Impact of Gamma Irradiation Effects on IGBT and Design Parameter Considerations

The primary dose effects on an insulated gate bipolar transistor (IGBT) irradiated with a ⁶⁰Co gamma‐ray source are found in both of the components of the threshold shifting due to oxide charge trapping in the MOS and the reduction of current gain in the bipolar transistor. In this letter, the IGBT macro‐model incorporating irradiation is implemented, and the electrical characteristics are analyzed by SPICE simulation and experiments. In addition, the collector current characteristics as a function of gate emitter voltage, V_GE, are compared with the model considering the radiation damage of different doses under positive biases.     

Radiation Effects on the Power MOSFET for Space Applications

The electrical characteristics of solid state devices such as the bipolar junction transistor (BJT), metal‐oxide semiconductor field‐effect transistor (MOSFET), and other active devices are altered by impinging photon radiation and temperature in the space environment. In this paper, the threshold voltage, the breakdown voltage, and the on‐resistance for two kinds of MOSFETs (200 V and 100 V of V_DSS) are tested for γ‐irradiation and compared with the electrical specifications under the pre‐ and post‐irradiation low dose rates of 4.97 and 9.55 rad/s as well as at a maximum total dose of 30 krad. In our experiment, the γ‐radiation facility using a low dose, available at Korea Atomic Energy Research Institute (KAERI), has been applied on two commercially available International Rectifier (IR) products, IRFP250 and IRF540.     

Electrothermal Analysis for Super‐Junction TMOSFET with Temperature Sensor

For a conventional power metal–oxide–semiconductor field‐effect transistor (MOSFET), there is a trade‐off between specific on‐state resistance and breakdown voltage. To overcome this trade‐off, a super‐junction trench MOSFET (TMOSFET) structure is suggested; within this structure, the ability to sense the temperature distribution of the TMOSFET is very important since heat is generated in the junction area, thus affecting its reliability. Generally, there are two types of temperature‐sensing structures — diode and resistive. In this paper, a diode‐type temperature‐sensing structure for a TMOSFET is designed for a brushless direct current motor with on‐resistance of 96 mΩ·mm². The temperature distribution for an ultra‐low on‐resistance power MOSFET has been analyzed for various bonding schemes. The multi‐bonding and stripe bonding cases show a maximum temperature that is lower than that for the single‐bonding case. It is shown that the metal resistance at the source area is non‐negligible and should therefore be considered depending on the application for current driving capability.     

Effects of TGF-β1 Receptor Inhibitor GW788388 on the Epithelial to Mesenchymal Transition of Peritoneal Mesothelial Cells

We investigated the effectiveness of the transforming growth factor beta-1 (TGF-β) receptor inhibitor {"type":"entrez-nucleotide","attrs":{"text":"GW788388","term_id":"293585730","term_text":"GW788388"}}GW788388 on the epithelial to mesenchymal transition (EMT) using human peritoneal mesothelial cells (HPMCs) and examined the effectiveness of {"type":"entrez-nucleotide","attrs":{"text":"GW788388","term_id":"293585730","term_text":"GW788388"}}GW788388 on the peritoneal membrane using a peritoneal fibrosis mouse model. HPMCs were treated with TGF-β with or without {"type":"entrez-nucleotide","attrs":{"text":"GW788388","term_id":"293585730","term_text":"GW788388"}}GW788388. Animal experiments were conducted on male C57/BL6 mice. Peritoneal fibrosis was induced by intraperitoneal injection of chlorhexidine gluconate. {"type":"entrez-nucleotide","attrs":{"text":"GW788388","term_id":"293585730","term_text":"GW788388"}}GW788388 was administered by once-daily oral gavage. The morphological change, cell migration, and invasion resulted from TGF-β treatment, but these changes were attenuated by cotreatment with {"type":"entrez-nucleotide","attrs":{"text":"GW788388","term_id":"293585730","term_text":"GW788388"}}GW788388. TGF-β-treated HPMCs decreased the level of the epithelial cell marker and increased the levels of the mesenchymal cell markers. Cotreatment with {"type":"entrez-nucleotide","attrs":{"text":"GW788388","term_id":"293585730","term_text":"GW788388"}}GW788388 reversed these changes. Phosphorylated Smad2 and Smad3 protein levels were stimulated with TGF-β and the change was attenuated by cotreatment with {"type":"entrez-nucleotide","attrs":{"text":"GW788388","term_id":"293585730","term_text":"GW788388"}}GW788388. For the peritoneal fibrosis mice, thickness and collagen deposition of parietal peritoneum was increased, but this change was attenuated by cotreatment with {"type":"entrez-nucleotide","attrs":{"text":"GW788388","term_id":"293585730","term_text":"GW788388"}}GW788388. {"type":"entrez-nucleotide","attrs":{"text":"GW788388","term_id":"293585730","term_text":"GW788388"}}GW788388, an orally available potent TGF-β receptor type 1 inhibitor, effectively attenuated TGF-β-induced EMT in HPMCs. Cotreatment with {"type":"entrez-nucleotide","attrs":{"text":"GW788388","term_id":"293585730","term_text":"GW788388"}}GW788388 improved peritoneal thickness and fibrosis, and recovered peritoneal membrane function in a peritoneal fibrosis mouse model.     

Honeycomblike large area LaB6 plasma source for Multi-Purpose Plasma facility

A Multi-Purpose Plasma (MP(2)) facility has been renovated from Hanbit mirror device [Kwon et al., Nucl. Fusion 43, 686 (2003)] by adopting the same philosophy of diversified plasma simulator (DiPS) [Chung et al., Contrib. Plasma Phys. 46, 354 (2006)] by installing two plasma sources: LaB(6) (dc) and helicon (rf) plasma sources; and making three distinct simulators: divertor plasma simulator, space propulsion simulator, and astrophysics simulator. During the first renovation stage, a honeycomblike large area LaB(6) (HLA-LaB(6)) cathode was developed for the divertor plasma simulator to improve the resistance against the thermal shock fragility for large and high density plasma generation. A HLA-LaB(6) cathode is composed of the one inner cathode with 4 in. diameter and the six outer cathodes with 2 in. diameter along with separate graphite heaters. The first plasma is generated with Ar gas and its properties are measured by the electric probes with various discharge currents and magnetic field configurations. Plasma density at the middle of central cell reaches up to 2.6 x 10(12) cm(-3), while the electron temperature remains around 3-3.5 eV at the low discharge current of less than 45 A, and the magnetic field intensity of 870 G. Unique features of electric property of heaters, plasma density profiles, is explained comparing with those of single LaB(6) cathode with 4 in. diameter in DiPS.     

Identification and in vitro immunosuppressive activity of a SDZ-IMM-125 metabolite isolated from phenobarbital-induced rabbit liver microsomes

1. A metabolite of D-serine-cyclosporine A has been isolated from phenobarbital induced rabbit liver microsomes using hplc. 2. This metabolite was identified by FAB, electrospray mass spectrometry as well as nmr spectroscopy and is the result of metabolism of the vinylic methyl group of the 9-carbon amino acid unique to the cyclosporins, the first amino acid of this cyclic undecapeptide. This metabolite exhibits a significantly lower immunosuppressive activity than IMM-125 and CsA.     

Large area ashing process using an atmospheric pressure plasma

We present an atmospheric pressure plasma processing for ashing photo-resist (PR) layer in the flat panel display and semiconductor manufacturing. Removal of KrF PR, i-line PR, and negative color filter PR layers on a 6th-generation large area (1640 × 30 mm²) substrate was investigated by making use of a dielectric barrier discharge (DBD) plasma device, which is with a large number of gas-flowing holes. The nitrogen DBD plasma was generated with a mixture of compressed dry air (CDA) and SF₆. To prevent thermal shrinkage of the PR layer, samples were maintained at a temperature less than 100 °C. Uniformity and reproducibility experiments have been carried out in terms of treatment time. Eventually, we obtained an ashing rate of about 600 nm/min for negative color filter PR, and 450 nm/min for KrF and i-line PR at a CDA concentration of 1%, a SF₆ concentration of 0.5%, a carrier N₂ gas flow rate of 1500 liters per minute (lpm) and at an applied power of 8 kW. Amorphous-Si layer loss which strongly depends on the fluorine radicals was at an acceptable level of 5 nm/min in the given conditions.