Evaluation of soft error rates using nuclear probes in bulk and SOI SRAMs with a technology node of 90 nm

The difference of soft error rates (SERs) in conventional bulk Si and silicon-on-insulator (SOI) static random access memories (SRAMs) with a technology node of 90 nm has been investigated by helium ion probes with energies ranging from 0.8 to 6.0 MeV and a dose of 75 ions/μm². The SERs in the SOI SRAM were also investigated by oxygen ion probes with energies ranging from 9.0 to 18.0 MeV and doses of 0.14–0.76 ions/μm². The soft error in the bulk and SOI SRAMs occurred by helium ion irradiation with energies at and above 1.95 and 2.10 MeV, respectively. The SER in the bulk SRAM saturated with ion energies at and above 2.5 MeV. The SER in the SOI SRAM became the highest by helium ion irradiation at 2.5 MeV and drastically decreased with increasing the ion energies above 2.5 MeV, in which helium ions at this energy range generated the maximum amount of excess charge carriers in a SOI body. The soft errors occurred by helium ions were induced by a floating body effect due to generated excess charge carriers in the channel regions. The soft error occurred by oxygen ion irradiation with energies at and above 10.5 MeV in the SOI SRAM. The SER in the SOI SRAM gradually increased with energies from 10.5 to 13.5 MeV and saturated at 18 MeV, in which the amount of charge carriers induced by oxygen ions in this energy range gradually increased. The computer calculation indicated that the oxygen ions with energies above 13.0 MeV generated more excess charge carriers than the critical charge of the 90 nm node SOI SRAM with the designed over-layer thickness. The soft errors, occurred by oxygen ions with energies at and below 12.5 MeV, were induced by a floating body effect due to the generated excess charge carriers in the channel regions and those with energies at and above 13.0 MeV were induced by both the floating body effect and generated excess carriers. The difference of the threshold energy of the oxygen ions between the experiment and the computer calculation might be due to the difference between the designed and real structures.     

Generation of overpressure due to condensation in moist air jet

In the present study,a computational fluid dynamics method has been applied to investigate the effects of initialdegree of supersaturation at reservoir condition on under-expanded sonic jet structures,such as Mach disk loca-tion and diameter,barrel shock wave and jet boundary.The axisymmetfic nozzle geometry investigated was aconverging nozzle with straight part.As a result,it was found that the overpressures due to condensation generateand the characteristics of flow with generation of overpressure due to condensation in the jet were different fromthose without condensation.     

Effect of nozzle geometry on the flow characteristics of spiral flow generated through an annular slit

In comparison with previous researches of swirling flow,spiral flow generated in the spiral nozzle has some differentflow characteristics.It does not need a forced tangential momentum to generate its velocity and has some differentmerits from the swirling flow such as long potential core and low tangential velocity.In this study,the effect of noz-zle geometry on the flow characteristics in spiral nozzle was investigated by experiment and computation.As a result,the flow characteristics obtained by experiment has a satisfactory agreement with computational results,quantita-tively and qualitatively.     

Effect of non-equilibrium condensation of moist air on unsteady behaviour of shock waves around a circular arc blade

The unsteady phenomena in the transonic flow around airfoils are observed in the flow field of fan,compressorblades and butterfly valves,and this often causes serious problems such as the aeroacoustic noise,the vibration.In the transonic or supersonic flow where vapour is contained in the main flow,the rapid expansion of the flowmay give rise to a non-equilibrium condensation.However,the effect of non-equilibrium condensation on thetransonic internal flows around the airfoil has not yet been clarified satisfactorily.In the present study,the effectof non-equilibrium condensation of moist air on the self-excited shock wave oscillation on a circular arc bladewas investigated numerically.The results showed that in the case with non-equilibrium condensation,frequenciesof the flow oscillation became smaller than those without the non-equilibrium condensation.     

Crystal Structure of an Archaeal Tyrosyl-tRNA Synthetase Bound to Photocaged L-Tyrosine and Its Potential Application to Time-Resolved X-ray Crystallography

Genetically encoded caged amino acids can be used to control the dynamics of protein activities and cellular localization in response to external cues. In the present study, we revealed the structural basis for the recognition of O-(2-nitrobenzyl)-L-tyrosine (oNBTyr) by its specific variant of Methanocaldococcus jannaschii tyrosyl-tRNA synthetase (oNBTyrRS), and then demonstrated its potential availability for time-resolved X-ray crystallography. The substrate-bound crystal structure of oNBTyrRS at a 2.79 Å resolution indicated that the replacement of tyrosine and leucine at positions 32 and 65 by glycine (Tyr32Gly and Leu65Gly, respectively) and Asp158Ser created sufficient space for entry of the bulky substitute into the amino acid binding pocket, while Glu in place of Leu162 formed a hydrogen bond with the nitro moiety of oNBTyr. We also produced an oNBTyr-containing lysozyme through a cell-free protein synthesis system derived from the Escherichia coli B95. ΔA strain with the UAG codon reassigned to the nonnatural amino acid. Another crystallographic study of the caged protein showed that the site-specifically incorporated oNBTyr was degraded to tyrosine by light irradiation of the crystals. Thus, cell-free protein synthesis of caged proteins with oNBTyr could facilitate time-resolved structural analysis of proteins, including medically important membrane proteins.     

Protoplast Transformation of Alkalophilic Bacillus sp. by Plasmid DNA

A method for transformation of alkalophilic Bacillus sp. A-59 (ATCC21591, alkaline amylase producing bacterium) with plasmid DNA was developed. Plasmid pHWl containing a chloramphenicol acetyltransferase gene was used as a vector, because chloramphenicol was the only antibiotic found to be stable at alkaline pH condition. Transformation was carried out by a protoplast method and addition of polyethylene glycol (PEG; final concentration 22.5%) was essential for transformation. Optimum pH values of the media and buffers were slightly higher than those used in transformation of Bacillus subtilis protoplasts. Through optimization of transformation conditions for alkalophilic Bacillus sp., the transformation efficiency was increased to approximately 10⁶ transformants per μg plasmid DNA.     

Potential mechanism involved in removal of hydrophobic pesticides from vegetables by hydrostatic pressure

In our previous study, we found that the removal rate of hydrophobic pesticide on cherry tomatoes shows the maximum by hydrostatic pressure treatment (HPT) around 75 MPa. The objective of this study was to investigate the causes of reduction in the removal rate above 75 MPa HPT. Separating cuticle from flesh of the cherry tomatoes after HPT and examining the pesticide residues in each part the following was found: the detectable pesticide amount in the flesh part showed little change from the non-treated samples. Ethanol was applied as the surrounding solution during pressurization so as to prevent the reattachment of pesticide and decrease water solubility, and removal efficiency declined little. The effect of HPT on removal rate time indicated no significant difference at 0.1 MPa, the optimum level to be at 75 MPa for a comparatively short time, and at 400 MPa removal rate increased with time.     

A RaPID Macrocyclic Peptide That Inhibits the Formation of α-Synuclein Amyloid Fibrils

There is considerable interest in drug discovery targeting the aggregation of α-synuclein (αSyn) since this molecular process is closely associated with Parkinson's disease. However, inhibiting αSyn aggregation remains a major challenge because of its highly dynamic nature which makes it difficult to form a stable binding complex with a drug molecule. Here, by exploiting Random non-standard Peptides Integrated Discovery (RaPID) system, we identified a macrocyclic peptide, BD1, that could interact with immobilized αSyn and inhibit the formation of fibrils. Furthermore, improving the solubility of BD1 suppresses the co-aggregation with αSyn fibrils while it kinetically inhibits more effectively without change in their morphology. We also revealed the molecular mechanism of kinetic inhibition, where peptides bind to fibril ends of αSyn, thereby preventing further growth of fibrils. These results suggest that our approach for generating non-standard macrocyclic peptides is a promising approach for developing potential therapeutics against neurodegeneration.     

Removal of pesticide residue in cherry tomato by hydrostatic pressure

The reduction of Chlorpyrifos (CP) in cherry tomatoes by High hydrostatic pressure (HHP) treatment was demonstrated and compared with other washing methods. CP is commonly used as a broad-spectrum insecticide in pest control, and high residual levels have been detected in vegetables. Samples were treated at several pressures (0.1–400 MPa) and at two temperatures (5 or 25 °C) for 30 min. The optimum HHP conditions for reducing CP were around 75 MPa at 5 °C, and the removal rate was about 75%. This removal rate is slightly higher than other treatments such as soaking in ethanol solution and ultrasonic, accompanied by no visual changes (color, size and shape) in appearance. Also, no toxic intermediates were identified in the extracts of the high-pressure treated cherry tomatoes under these experimental conditions. The present results indicate that HHP can be a useful choice for removing residual pesticides.