Study of interface state generation in thin oxynitride gate dielectrics under hot-electron stressing

The hot-electron-induced interface state generation in thin ( approximately 8.6 nm) oxynitride films prepared by rapid thermal reoxidation (RTO) of rapidly thermal nitrided (RTN) SiO/sub 2/ have been studied. Both MOS capacitors and MOSFETs were used as testing devices. For MOSFETs charge-pumping current I/sub cp/ measurement was performed to monitor the increase Delta D/sub it/ of interface state density. It is found that the optimised RTN and RTO processes could produce devices with a significantly improved resistance against the hot electron-induced interface state generation.<>     

Spectral-domain analysis of E-plane waveguide tomicrostrip transitions

The spectral-domain technique and a residue calculus theorem are used to compute the input impedance of a microstrip transition to a rectangular waveguide. The transition consists of a printed circuit board inserted into a waveguide housing along the E-plane. The effects of the dielectric layer are considered in the present analysis. The behavior of the input impedance of the transition is studied with respect to the critical dimensions of the probe length and backshort location. Calculated results by the new formulation agree well with those computed using an integral equation and those measured at Ka -band frequencies     

Quantitative analysis of low molecular weight polar compounds by continuous flow liquid secondary ion tandem mass spectrometry

Quantitative analyses of low molecular weight (100-200) polar compounds [1-methyl-4-phenylpyridine (MPP+), 2-amino-3-(methylamino)propanoic acid (synonyms, beta-(methyl-amino)-L-alanine or BMAA), and tryptophan] were conducted on a triple-stage quadrupole mass spectrometer configured for continuous flow liquid secondary ion mass spectrometry ionization (CF L-SIMS). It is shown that quantification by CF L-SIMS at subnanogram sensitivity can be precise (correlation coefficients greater than 0.99), accurate, specific, and routine for compounds not measurable by static L-SIMS. Successful analyses, however, are strongly dependent upon the stability of the film formed by the mobile phase on the probe tip. In our system, film stability is affected by mobile phase composition and flow rate, ion source and probe tip temperature, probe-tip and capillary alignment, film thickness, and sample composition.     

Mixed modifier effect in lithium‐calcium borosilicate glasses

The mixed modifier effect (MME) in the lithium‐calcium borosilicate glasses, which have a composition of 0.4[(1?x)Li₂O–xCaO]–0.6[(1?y)B₂O₃–ySiO₂] with x in the range of 0~1 and y in the range of 0.33~0.83, is investigated. The MME manifests itself as a positive deviation from linearity in the activation energy of electrical conductivity (Ea^σ) and as a negative deviation from linearity in the fraction of four‐coordinated boron (N₄), glass transition temperature (T_g), dilatometric softening temperature (T_d), Vickers microhardness (H_v), dielectric constant (ε), and dielectric loss (tanδ). Moreover, the deviation, which exhibits a maximum at [CaO]/([CaO]+[Li₂O])=0.5, is enhanced with increasing [SiO₂]/[B₂O₃] ratio in the glass network. The observed MME in T_g, T_d, and H_v are attributed to the bond weakening in the network; however, the MME in ε, tanδ, and Ea^σ are caused by the obstruction of modifier transport in the glass network.     

High methanol oxidation activity of electrocatalysts supported by directly grown nitrogen-containing carbon nanotubes on carbon cloth

The microstructure and electrochemical activity of the Pt-Ru supported by nitrogen-containing carbon nanotubes (CN_x NTs) directly grown on the carbon cloth have been investigated. The CN_x NTs directly grown on the carbon cloth (CN_x NTs-carbon cloth composite electrode) were synthesized using microwave-plasma-enhanced chemical vapour deposition first and then use as the template to support the Pt-Ru nanoclusters subsequently sputtered on. The ferricyanide/ferrocyanide redox reaction in cyclic voltammetry (CV) measurements showed a faster electron transfer on the CN_x NTs-carbon cloth composite electrode than the one with carbon cloth alone. Comparing their methanol oxidation abilities, it is found that the Pt-Ru nanoclusters supported by the CN_x NTs-carbon cloth composite electrode have considerably higher electrocatalytic activity than the carbon cloth counterpart. This result suggests high performance of the CN_x NTs-carbon cloth composite electrode, and demonstrates its suitability for direct methanol fuel cell applications.     

Adsorption of color dyestuffs on polyurethane–chitosan blends

This study made use of poly(ethylene glycol) (PEG) samples of different molecular weights, which were reacted with a diisocyanate ester, and an anion center for the synthesis of polyurethane (PU), which was then mixed with chitosan to form a polymer adsorbent. It was tested for the determination of its adsorption toward acidic dyestuffs under various conditions. Our results showed that under all the tested conditions, the blended polymer adsorbent possessed a better adsorbing ability than chitosan by itself, and the degree of adsorption varied positively as the adsorbent concentration, ambient temperature, and contact time increased. Furthermore, the addition of PU remarkably increased the adsorption efficiency, whereas PEG with a greater molecular weight yielded a better adsorption performance. As for the dyestuffs, the red one surpassed the others in adsorption efficiency. Finally, a 5 mg/mL concentration of the adsorbent solution, a temperature of 45°C, and a contact time of 15 min gave fairly good adsorption results. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3991–3998, 2004     

Dynamic modeling of the mold filling process in an injection molding machine

This paper presents the development of a nonlinear mathematical model for the study of the mold filling process in an injection molding machine. The model is formulated by the Reynolds transport theorem which is applied to describe the polymer flow dynamics. The mold filling process can be approximated by the transient phenomenon of the non-Newtonian fluids flowing through a closed conduit. The comparison between the experimental results and the theoretical simulation indicate that the nonlinear model is a reasonable representation of the mold filling dynamics when the acrylonitrile-butadiene-styrene (ABS) is injected into a disk shape mold. The actuation system dynamics of an injection molding machine are also investigated. The results indicate that the nonlinear model can also adequately predict the transient behavior of the actuation system.     

An Investigation of using statistically designed experiments and a computer model

This paper outlines the results of an experimental program aimed at established the best formation parameters for dynamic Zr (IV) — PAA membranes formed on porous ceramic supports. The membrane formation parameters investigated are the pressure, the circulation velocity, the Zr (IV) concentration, and the PAA concentration. The formation pressure was allowed to vary between 200 psig (1.4 MP_a) to 800 psig (5.4 MP_a), the circulation velocity from 6 fps (1.8 m/s) to 24 fps (7.3 m/s), the Zr (IV) concentration from 10^-4M to 9 × 10^-4M, and the PAA concentration from 50 ppm to 250 ppm.Twenty statistically designed experiments were conducted to evaluate the effect of these four parameters on the flux and rejection of the resulting membrane at the end of the formation procedure. The results were used in a multiple linear regression computer program named BMD-PIR which develops the measured values with an accuracy of +_ 2 percent. Using these models, it is possible to form a membrane with a given value of flux or rejection within their ranges.For the range of variables used in this study, the maximum membrane rejection was 91% corresponding to a flux of 10 gpd/ft²(1.7 cm/hr) for 0.05 M NaCl and 800 psi (5.4 MP_a). High rejection was obtained by increasing the membrane formation pressure and by increasing the PAA concentration. High flux can be achieved by increasing the formation pressure, by increasing the Zr (IV) concentration up to 9.0 × 10^-4M -, and by increasing the circulation velocity.