The design, analysis, and development of highly manufacturable 6-T SRAM bitcells for SoC applications

We present here an extensive static random access memory (SRAM) bitcell development methodology that has led to the qualification and production of the smallest 6-T SRAM bitcell reported in 0.13-/spl mu/m CMOS technology. No additional processing steps were employed in accomplishing this result. Such a methodology is being extended also to subsequent technology generations. The development efforts included the electrical evaluation of several candidate 6-T SRAM bitcell architectures for both high-density and high-speed applications. Based on the electrical evaluations, the chosen cell architectures were incorporated in silicon and verified for their robustness with respect to critical design rules, yields and reliability. The methodology for optical proximity correction for bitcell development has been described here. Minor process enhancements to ensure compatibility of the overall process flow with the SRAM bitcells are described. The use of SRAM-specific electrical test structures serves an important role in validating the electrical performance and confirming the robustness of the bitcells in a manufacturing environment. The monitoring of V/sub ddmin/, the minimum voltage at which the memory is functional was used to drive overall process improvements and reliability. Lastly, measurements of soft error rates demonstrated excellent immunity of the bitcells to single event upsets.     

Use of pore network models to interpret laboratory experiments on vugular rocks

Laboratory evaluation of recovery behavior in vugular rocks is unreliable because pore features are relatively large. 3-d Computed Tomography (CT) images of the porosity and of multi-rate waterfloods in a vugular sample show that conventional analysis is inadequate. Through parametric studies, we determine whether our large pore network models contain characteristics observed in the core floods. We then calibrate our models to laboratory inputs to improve quantitative interpretation.     

Prediction of operating range of rotor speeds for rotating disc contactors

This paper reports on the optimum range of rotor speeds for the operation of Rotating Disc Contactors (RDC). New information based on experimental investigations is presented regarding the existence of a second critical rotor speed which divides the varying characteristic velocity region into rapidly varying and gradually varying characteristic velocity regions of the dispersed phase droplets. New modifications to the reported generalised correlations for the prediction of characteristic velocity at all rotor speeds under conditions of no solute transfer as well as solute transfer between dispersed and continuous phases are suggested.     

Studies on castor oil. II. Hydrogenation of castor oil

1. Products of low iodine value (<10.0) and hydroxyl value (35–40) can be readily obtained by hydrogenating castor oil at atmospheric pressure and at temperatures of the order of 220°, using 1.0% Raney nickel.
2. Dehydration of ricinoleic acid and subsequent hydrogenation of the resulting double bond as also simple saturation of ricinoleic acid are the main reactions occurring during the hydrogenation of castor oil under ordinary conditions.
3. Increase in the amount of catalyst favors more the hydrogenation of double bond at lower temperatures and both dehydration and hydrogenation at about 220°, which seems to be the optimum temperature for the maximum conversion of ricinoleic acid into nonhydroxy acids with both Raney and dryreduced nickel at atmospheric pressures.
4. Higher proportions of catalyst, addition of catalyst stepwise, and higher temperature of hydrogenation cause considerable splitting and estolide formation.
5. When hydrogenation is carried out at room temperature, under a pressure of 40 p.s.i. with alcohol as solvent, a product rich in monohydroxy stearic acid is obtained.
6. True unsaturation of hydrogenated castor oil is measured by the Wijs method at 15–20°C.

     

Observation of keyhole-mode laser melting in laser powder-bed fusion additive manufacturing

Laser powder-bed fusion additive manufacturing of metals employs high-power focused laser beams. Typically, the depth of the molten pool is controlled by conduction of heat in the underlying solid material. But, under certain conditions, the mechanism of melting can change from conduction to so-called “keyhole-mode” laser melting. In this mode, the depth of the molten pool is controlled by evaporation of the metal. Keyhole-mode laser melting results in melt pool depths that can be much deeper than observed in conduction mode. In addition, the collapse of the vapor cavity that is formed by the evaporation of the metal can result in a trail of voids in the wake of the laser beam. In this paper, the experimental observation of keyhole-mode laser melting in a laser powder-bed fusion additive manufacturing setting for 316L stainless steel is presented. The conditions required to transition from conduction controlled melting to keyhole-mode melting are identified.     

Factors governing the electrochemical synthesis of α-nickel (ii) hydroxide

The electrodeposition of -nickel hydroxide is promoted by the simultaneous chemical corrosion of the electrode by an acidic nitrate bath. Chemical corrosion results in the formation of a poorly ordered layered phase which is structurally similar to -nickel hydroxide and provides nucleation sites for the deposition of the latter. Therefore under conditions which enhance corrosion rates such as low current density (<1.3 mA cm–2), high temperature (60 C), high nickel nitrate concentration ( 1M) and the resultant low pH (1.7), -nickel hydroxide electrodeposition is observed, while -nickel hydroxide forms under other conditions. Further, -nickel hydroxide deposition is more facile on an iron electrode compared to nickel or platinum.     

Facile Development of Iron-Platinum Nanoparticles to Harness Multifunctionality in Single Entity

Engineered magnetic nanosystems exhibit attractive options for implementing unique diagnostic options and therapeutic solutions in biomedical applications. Here we report a facile, thermo-free and aqueous synthetic method to prepare ascorbic acid-stabilized iron-platinum nanoparticles. The effects of reducing agent, pH and sequence of precursor addition are investigated, and optimized reaction condition is identified to obtain a unique iron-platinum(Pt-FePt)nanosystems. The multifunctionality of the developed nanosystem has been realized by catalytic efficiency of platinum for therapeutic application and superparamagnetic property of Fe Pt for magnetic resonance imaging contrast enhancement.Moreover, the multifunctional imaging and therapeutic activities have been achieved at physiological pH. The developed multifunctional nanoparticles are monodisperse with uniform morphology as well as stable in solution and non-toxic.     

Effect of Ultrasound on Molecular Structure Development of Polylactide

In this work, effect of ultrasound on molecular structure development of Polylactide (PLA) was studied. It was found that the intrinsic viscosity of PLA decreased with increasing treating time, temperature and ultrasound time. Different from traditional thermal degradation of PLA, the degradation of PLA under ultrasound treatment showed that chain scission and chain combination of PLA competed with each other in the degradation process, which could be divided into two steps. The mechanism of ultrasound degradation of PLA was proposed. Furthermore, Thermal properties were characterized by DSC to show heat and ultrasound effects on molecular structure development of PLA.     

Modeling multistream heat exchangers with and without phase changes for simultaneous optimization and heat integration

A new equation‐oriented process model for multistream heat exchangers (MHEX) is presented with a special emphasis on handling phase changes. The model internally uses the pinch concept to ensure the minimum driving force criteria. Streams capable of phase change are split into substreams corresponding to each of the phases. A novel disjunctive representation is proposed that identifies the phases traversed by a stream during heat exchange and assigns appropriate heat loads and temperatures for heat integration. The disjunctive model can be reformulated to avoid Boolean (or integer) variables using inner minimization and complementarity constraints. The model is suitable for optimization studies, particularly when the phases of the streams at the entry and exit of the MHEX are not known a priori. The capability of the model is illustrated using two case studies based on cryogenic applications. © 2011 American Institute of Chemical Engineers AIChE J, 2012