Implications of Dopant-Fluctuation-Induced $V_{rm t}$ Variations on the Radiation Hardness of Deep Submicrometer CMOS SRAMs

Accurately analyzing the single-event (SE) vulnerability of static random-access memory (SRAM) cells leads to precisely calculated soft-error rates (SERs). Random dopant-fluctuation-induced V_t variations affect the SE vulnerability of these memory cells and increase the intercell spread in critical charge (Q_crit), which cause SE upsets. This might consequently lead to higher SERs than would be calculated, assuming a single critical charge. Monte Carlo simulations in the IBM 130- and 90-nm technologies quantify this spread in Q_crit and in SRAM soft-error cross sections with increasing variance. For a radiation-tolerant design, a statistical-design methodology must be used to validate existing hardening schemes and to obtain the expected tolerance levels.     

The application of the least squates finite element method to Abel's integral equation

Abel's integral equation is the governing equation for certain problems in physics and engineering, such as radiation from distributed sources. The finite element method for the soultion of this non-linear equation is presented for problems with cylindrical symmetry and the extension to more general integral equations is indicated. The technique was applied to an axisymmetric glow discharge problem and the results show excellent agreement with previously obtained solutions.     

A New Fourier Method for Evaluating Generation System Reliability Indices

A new, robust, and computationally efficient Fourier method for evaluating the loss of load probability and expected value of energy not served in a generation system is presented in this paper. An efficient algorithm is developed for computirg the transformed probability density function of outages of all the generatig units of the system. The fast Fourier transform algorithm is then used for transforming the load duration curve, and for inverse transformation of the product of the transformed outage function and the transformed load duration curve. As the method does not involve any epproximation, it is expected to yield highly accurate results in all situations. Being a Fourier domain method, significant savirg in computational effort results for systems with identical units. The application of the method is illustrated for a typical medium-sized system.     

s̱-expected busy period of the service facility of a 1-server n-unit system subject to arbitrary failure and different repair strategies

This paper deals with the s?-expected busy period of a n-unit system with a single repair facility. The service facility is called for whenever r (1 ≤ r ≤ n) units are in failed condition and is retained until no unit is waiting for repair. The analysis is carried out under the assumption that the time to failure of a unit is arbitrarily distributed while the service rate is constant. The case when n = 2 with the failure time distribution is 2-stage Erlangian is discussed.     

Alteration of dynamic quaternary structure and calcium-binding ability of beta-crystallin by light

beta-crystallin, one of the three main constituent proteins of the eye lens, exists as an equilibrium population of oligomeric (beta H), trimeric (beta L1) and dimeric (beta L2) species. This equilibrium is dependent on various factors such as the protein concentration, ionic strength and pH of the medium. We have studied the effect of ultraviolet B radiation on the aggregational patterns of beta-crystallin, using size-exclusion chromatography. Irradiation of a solution of beta H-crystallin at 295 nm for about 30 min causes the deaggregation of the hexameric population into dimers. Irradiation for a longer time, however, produces cross-linked high molecular weight products. Irradiation of a beta L2 solution for 30 min does not perturb the elution profile, while irradiation for a longer time increases the content of beta L1 (trimeric) crystallin. Irradiation also causes a decrease in the calcium-binding affinity of the beta-crystallins.     

Experimental investigation of the thermodynamics of Fe-Nb-C austenite and nonstoichiometric niobium and titanium carbides (T = 1273 to 1473 K)

The thermodynamics of Fe-Nb-C austenite and nonstoichiometric binary niobium carbide and titanium carbide in the temperature range of 1273 to 1473 K has been investigated using a dynamic gas equilibration technique. Methane-hydrogen mixtures have been used for fixing carbon potentials, and the carbon contents have been determined as dynamic weight changesvia a sensitive Cahn microbalance. The niobium-carbon interactions, similar to the titaniumcarbon interactions, are manifested as a minimum in the niobium carbide solubility in austenite, as increased amounts of dissolved carbon with niobium additions, and as the variation of solubility limit of the carbide with carbon content at high carbon levels. The results on the isoactivity measurements in the ternary Fe-Nb-C have been analyzed using the modified Wagner formalism, and the ternary interaction parameter ε _C ^Nb has been evaluated. The solubility of niobium carbide in Fe-Nb-C in austenite has been determined as the deflection in the variation of carbon content with Nb additions at constant carbon activity. The dissolution free energy of body-centered cubic (bcc) Nb in face-centered cubic (fcc) Fe has also been determined from the solubility data. Rational correlation between the dissolution free energies of transition metal solutes in fcc Fe and the group number in the Periodic Table has been shown to exist. A correlational relationship between the ternary interaction parameter and the free energy of formation of carbides has been established. These relationships are utilized in the assessment, as well as the systematization of thermodynamic data. The results on the activity-composition relationship in the binary niobium and titanium carbides have been analyzed using the sublattice-subregular model proposed by Hillert and Staffansson, [2] and the interaction parameters in the model were determined. The thermodynamic calculations based on this model and our experimental results were carried out, and very good agreement between experimental and calculated results was obtained. K. BALASUBRAMANIAN, Formerly with McMaster University,     

Metal ion stimulation of phospholipase D-like activity of isolated rat intestinal mitochondria

OBJECTIVE: To investigate the role of phospholipase during the activation and priming of neutrophil nicotinamide adenine dinucleotide phosphate (NADPH) oxidase by peritoneal dialysis effluent (PDE). DESIGN: Examine the action of 4-hour dwell PDE upon phospholipase activation in the circulating neutrophils obtained from healthy individuals. RESULTS: We have previously reported that PDE stimulated superoxide release by the NADPH oxidase of human neutrophils and primed the response to the bacterial peptide, fMLP (fMetLeuPhe). To elucidate the biochemical mechanisms underlying these observations, we have examined the roles of phospholipases (PL) C, D, and A2, whose activation causes the release of a range of intracellular secondary messengers. Following fMLP stimulation, we observed a rapid activation of both PLC and PLD as well as a small but nonsignificant increase in PLA2 activity. Peritoneal dialysis effluent alone failed to stimulate either PLC or PLD, while pre-incubation with PDE had no affect upon fMLP-induced PLC and PLD activation. However, PDE caused a small but nonsignificant increase in PLA2 activity (which was comparable to that observed with fMLP) and primed the fMLP-induced response. In common with a role for PLA2 and the subsequent release of arachidonic acid (AA), we have demonstrated dose-dependent inhibition of PDE-induced superoxide release by the PLA2 inhibitor mepacrine, as well as activation and priming of the fMLP-induced superoxide generation by AA. CONCLUSIONS: These results imply that PDE-induced NADPH-oxidase activation and priming in human neutrophils is mediated via a PLA2-dependent but PLC- and PLD-independent mechanism.     

Kinetics of oxidation of pseudocumene in the vapor phase

The kinetics of pseudocumene oxidation in the vapor phase with tin vanadate as catalyst have been studied over the following ranges of the variables: Oxygen concentration, 0.909 to 2.857 mole/m³; pseudocumene concentration, 0.071 to 0.125 mole/m³; temperature, 260 to 320°C; space time, 22.5 to 90 × 10⁴ g. catalyst/mole sec. Oxidation-reduction models have been found to describe the kinetics adequately. The mechanism is found to remain the same throughout the temperature range covered.     

An assessment of carburization-decarburizatton behaviour of Fe-9Cr-Mo steels in a sodium environment

A critical assessment is made of the carburization-decarburization kinetics of Fe-9Cr-Mo steels exposed to a sodium environment, using the available information on carbide phase morphology, chromium activity in a ferrite matrix, chromium carbide activity in mixed carbides, carbon solubility in Cr-Mo ferritic steels, and activity-concentration relationships based on α-phase/M₆C or M₂₃C₆carbide equilibrium. Experimental data are presented on the decarburization of Fe-5Cr-Mo and Fe-9Cr-Mo steels at 973 K in a sodium environment to ascertain the long-term behaviour of these steels. The analysis shows that the decarburization of ferritic steels is largely dependent on the chemical reaction at the carbide/α interface and that at carbon activities <0.04, the rate is predominantly determined by the dissolution of (Fe, Mo)₆C carbides.