MASS TRANSFER IN GAS-SPARGED POROUS ELECTRODES

The electrochemical limiting current method was used to measure mass transfer coefficients with cocurrent upward gas-liquid flow in packed bed electrodes. Liquid-solid and overall gas-solid coefficients were determined from limiting current data in the presence of inert or reactive gas flows with the use of a plug flow model. The presence of inert gas flow increased mass transfer coefficients over those in single-phase flow by a factor of up to 1.7. As a result of boundary layer penetration by gas bubbles, sparging with reactive gas increased mass transfer rates by a factor of up to 3.5.     

CAFTURE AND RECYCLE OF BYPASSING BUBBLE GAS IN A FLUIDIZED BED: THE “BUBBLE EATER”

The bubble eater is a device which can sense, capture, and recycle bubble gas in a bubbling fluidized bed. The theory describing the enhancement of reactant gas conversion are presented and illustrated by means of a numerical example.     

MODELING LIQUID MASS TRANSFER IN HIGEE SEPARATION PROCESS

Correspondence concerning this paper should be addressed to Professor Richard S.H. Mah. Hsien-Hsin Tung is now affiliated with Department of Chemical Engineering, California Institute of Technology

Penetration theory is used to describe the liquid mass transfer in Higee separation process. Within a possible range of effective areas, it is shown that the predicted mass transfer coefficients are in reasonable agreement with the estimated mass transfer coefficients. The estimated coefficients were calculated from the experimental data and the possible effective areas. Hence it is concluded the penetration theory is generally applicable to describe liquid mass transfer in Higee separation process. The comparison also suggests that liquid mixing at the junctions of packing materials may be more complete in Higee process than in traditional process.     

The Effects of Cyclic Terminal Groups in 4-Aminoazo-benzene and Related Azo Dyes: Part 21—pKa Values of Some Monoazo Dyes Derived from

Basicity values have been determined for series of monoazo dyes incorporating a pyrrolidino or a piperidino moiety. In general, the pK_a value is found to decrease as the donor capacity of the terminal nitrogen atom decreases.The basicities of the 4'-substituted piperidinoazobenzenes decrease as the electron withdrawing strength of the 4'-substituent increases. However, the pK_a values of the related pyrrolidino compounds appear to be insensitive to the substituent.     

THE QUEST FOR WORLD CLASS IT CAPABILITY IT Is Key to Achieving Quality Goals

In today's competitive world, many organizations are pursuing total quality improvement programs, and as a result of these initiatives, are seeking to define world class capabilities. The organizations with these aspirations are trying to improve product and service quality, business process quality, or delivered quality, and are becoming aware that information technology is playing a more substantial role in realizing these quality goals.     

Overcoming contextual limitations on problem-solving transfer.

Five experiments investigated transfer from multiple analogs to a superficially dissimilar target problem. When subjects explicitly compared the analogs and then immediately attempted to solve the target problem in the context of a single experiment, transfer was obtained with significant frequency even without a hint that the analogs and target were related. Prehint transfer was sharply reduced or eliminated when the source analogs and the target were presented in different contexts, even when the transfer test was immediate. However, prehint transfer was enhanced, even after a context shift and a week-long delay between reading the source analogs and solving the problem, when the following conditions were met: The target problem was reworded slightly to emphasize a structural feature that it shared with the analogs; three rather than two source analogs were provided; and detailed, schema-oriented questions were used to help subjects focus on the problem-relevant aspects of the stories. Although spontaneous transfer between small numbers of dissimilar analogs is difficult to obtain, it can be achieved by manipulations that foster abstraction of a problem schema from the training examples. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

NONDESTRUCTIVE EXAMINATION OF EPOXY ADHESIVE-BONDED STRUCTURES EXPOSED TO A HUMID ENVIRONMENT: A COMPARISONOF LOW- AND HIGH-FREQUENCY DIELECTRIC MEASUREMENTS

Broadband dielectric measurements (10 -2 to 3 GHz) are reported on the effects of exposure of thick film adhesive-bonded structures to moisture. Measurement of the dielectric properties over a broad frequency range allows identification of water both in voids and as a molecular dispersion in the matrix. Changes in the low frequency region of the dielectric spectrum can be attributed to a combination of processes associated with plasticisation of the adhesive, interfacial polarisation effects, and hydration of the surface oxide layer. The data obtained are complemented by mechanical testing and failure analysis of the bond structure measured as a function of the time of exposure. This study indicates that for thick film adhesives the ageing characteristics are apparently independent of the surface treatment. In one of the joints studied an additional feature is identified which appears to correlate with the premature aging of the joint structure.     

Alcoholism at the time of injury among trauma center patients: Vehicular crash victims compared with other patients

A structured in-depth interview employing standardized criteria was used to determine the prevalence of lifetime and current alcohol dependence (alcoholism) in unselected consecutive patients admitted to a regional Level I trauma center. Of 629 patients, 157 (25.0%) were current alcoholics at the time of injury. An additional 87 (13.8%) were diagnosed as lifetime non-current alcoholics. There was no significant difference in the rates of current alcohol dependence among patients injured in vehicular crashes (23.5%), other unintentional trauma victims (29.3%), and those injured as a result of violence (24.6%). Of BAC + (blood alcohol concentration positive) patients, 54.5% were current alcoholics. However, 14.4% of alcohol-negative patients were also diagnosed as alcohol dependent.     

Thermogravimetric Determination of Carbon, Nitrogen, and Oxygen in Aluminum Nitride

A thermogravimetric method for the measurement of carbon, nitrogen, and oxygen in aluminum nitride is described. Since carbon oxidation occurs at lower temperatures than the oxidation of the aluminum compounds, thermogravimetric analyses in the respective temperature regimes can yield measurement of the oxygen, nitrogen, and carbon content. Thermogravimetric analyses were performed on mixtures of aluminum nitride and carbon with various concentrations in order to evaluate the accuracy of this method. The results were compared with those obtained by the hot gas extraction method. Errors produced by overlapping of the temperature ranges of the reactions were evaluated and experimental conditions were optimized to minimize error. This method can produce reliable results at elemental concentrations higher than a few percent. The absolute errors of the C/AI, N/Al, and O/Al atomic ratios were less then 0.02. The detection limit was evaluated to 0.2 wt% of each element. The applicability of the method to the study of the kinetics of the nitridation reaction was demonstrated.