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  • 1965-1969  (271)
  • 1920-1924
  • 1840-1849
  • 1968  (271)
  • Chemical Engineering  (257)
  • Psychopharmacology  (14)
  • 1
    ISSN: 1432-2072
    Keywords: Benzodiazepines ; Psychopharmacology ; Antianxiety ; Drug Tolerance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Oxazepam has two opposing actions on behavior: a responsedecreasing or depressant action and a response-increasing or disinhibitory action. The course of the two actions in chronic dosing was determined in rats in a test in which punished and unpunished schedules of reinforcement were alternated. The depressant action (measured by a decrease in the rate of unpunished behavior) was observed to undergo tolerance after 3–4 doses, while the disinhibitory action (measured by an increase in the rate of punished behavior) failed to show tolerance and even increased throughout the chronic series. The selective tolerance of the depressant action is probably due to neuronal adaptation, but changes in metabolism also may be involved. The increase in the rate of punished behavior is attributed, at least in part, to a progressive unmasking of the disinhibitory action as tolerance to the depressive action develops.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 13 (1968), S. 118-128 
    ISSN: 1432-2072
    Keywords: Psychopharmacology ; Diagnosis ; Sampling Studies ; Statistics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Theoretical models for sample selection by diagnosis using one, one-out-of-two, two, two-out-of-three, and three concurring opinions are illustrated. These models are then applied to two categories, schizophrenia and depressive disorders, for an actual sample of patients diagnosed by multiple observers. The conclusion is reached that sample selection by a single opinion is not sufficiently reliable for research studies. The choice of alternative methods of selection depends on the needs of a particular study. Samples chosen on the basis of two-out-of-three concurring opinions provide the least total error. When erroneous inclusions are particularly undesirable, higher degrees of consensus—e.g. agreeing pairs or triplets—are necessary.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 13 (1968), S. 129-139 
    ISSN: 1432-2072
    Keywords: Electroencephalography ; Psychopharmacology ; Imipramine ; Amphetamine ; Physostigmine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The results of the interaction of imipramine, physostigmine and d/l amphetamine in various intravenously administered dosages were studied on the cortical and subcortical electrical activity of cats. Imipramine was shown to cause a cortical synchronization, hippocampal desynchronization, rise in the threshold of electrocortical arousal and limbic convulsive activity which was potentiated by amphetamine. Imipramine increased the amount of physostigmine, but decreased the amount of amphetamine needed for cortical desynchronization. The possible significance of these findings for the neuropsychopharmacological action of imipramine is briefly discussed.
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  • 4
    ISSN: 1432-2072
    Keywords: Indoleamine Metabolism ; Psychopharmacology ; Antidepressive Drugs ; Amphetamine Derivatives (Chlorinated) ; Depression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary CMA (p-chloro-N-methylamphetamine) lowers the cerebral 5-HT concentration in test animals but has virtually no effect on the catecholamine concentrations. Moreover, this compound was found to behave in depressive patients like an antidepressive drug, not like a central stimulant of the amphetmine type. The study described was conducted in order to establish whether CMA influences the overall metabolism of indoleamines in man. Such an influence was clearly demonstrable. Our findings are consistent with the hypothesis that CMA releases 5-HT from its depots. It has not been explained why a considerable proportion of the released 5-HT is excreted unchanged and why the increase in 5-HIAA excretion is so small: the overall activity of MAO was found not to be inhibited. No indications of abnormal 5-HT degradation were found at this time. Patients with vital depressions who improved on CMA medication showed a lower 5-HIAA excretion before treatment than did patients who were refractory to CMA treatment. This is consistent with earlier observations. The possible cause of this phenomenon is discussed. Among the various possibilities considered, an abnormal 5-HT metabolism is regarded as the most plausible. Pertinent investigations are being continued.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 12 (1968), S. 384-399 
    ISSN: 1432-2072
    Keywords: Psychopharmacology ; Tranquilizing Agents ; Chlordiazepoxide ; Frustration ; Animal Behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This experiment investigated the possibility that chlordiazepoxide (CDP) has unique properties that account for state dependent learning, and prevention of conflict-induced behavior fixations. One group of rats were given a discrimination problem on a Lashley jumping stand, but on even days all responses were punished. Another group were treated the same way except than on even days all responses were rewarded. Each of these groups were subdivided, half of the Ss were given CDP on even days, the other half no drug. The results showed that punishment on even days for the response to be learned disrupted learning more than reward for responses that were to be avoided. CDP practically eliminated these disruptive effects and aided learning for the punishment group, but led to a slower rate of learning for the reward group. These findings confirmed the hypothesis that CDP attenuates the effects of negative incentives, and that this property accounts for the drug's cue value in discrimination learning and for its fixation prevention characteristics.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 12 (1968), S. 371-383 
    ISSN: 1432-2072
    Keywords: Psychopharmacology ; Cholinergic Blocking Drugs ; Animal Behavior ; Scopolamine ; Conditioned Reflex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Atropine or scopolamine improved conditioned avoidance behavior for most rats which performed poorly, in spite of extensive training, in a shuttle-box procedure. As previously reported, d-amphetamine also improved performance in many of these animals, but there was no particular relationship between a rat's responses to the cholinergic blocking agents and to d-amphetamine. The effect of any one of the 3 agents was, for the most part, reversible after the drug effect had dissipated. Physostigmine was quite potent in disrupting avoidance behavior in rats that performed well in the shuttle-box, even in animals that were overtrained. This impairment was antagonized by atropine or scopolamine, partly antagonized by d-amphetamine, and not antagonized by methyl atropine. Poor performers were found to be very sensitive to the disruptive effects of physostigmine, losing much of their escape behavior after relatively small doses. The results are interpreted as evidence for a central cholinergic system with inhibitory influences for modulating stimulus-response patterns. Under normal circumstances this inhibitory system probably functions in an integrated manner with the adrenergic mobilizing system for the central control of learned behavior. Centrally-active anticholinergic drugs of the muscarinic type appear to influence behavioral responses by inducing a response disinhibition.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-2072
    Keywords: Psychopharmacology ; Electrophysiology ; Arousal ; Animal Behavior ; Brain Biogenic Amines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have studied the interactions of reserpine and the monoamine oxidase inhibitors, nialamide and isocarboxazid, in rabbits. EEG recordings were made from animals with acute and chronically implanted electrodes. Gross behavioral observations were made in freely moving rabbits and brain amine concentrations of norepinephrine and serotonin were also determined. Emphasis was placed on observing drug effects over periods of time ranging up to 13 days. Rabbits given isocarboxazid or nialamide alone exhibit a phenomenon rarely seen in the control animals, namely partial activation, an EEG pattern in which slow waves of high amplitude are maintained in the cortex while fast activity appears in subcortical structures. This effect was also observed in rabbits treated with nialamide and reserpine in combination. By appropriate dosage schedules in which reserpine was administered to animals pretreated with monoamine oxidase inhibitors it was possible to maintain extended periods of frank arousal or EEG activation over a period of several days. The absolute concentrations of brain amines bore little or no relationship to the EEG effects observed, however, increased ratios of serotonin to norepinephrine were observed in conjunction with EEG activation and signs of behavioral excitement.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 12 (1968), S. 414-423 
    ISSN: 1432-2072
    Keywords: Psychopharmacology ; Barbiturates ; Phenothiazines ; Animal Behavior ; Motor Coordination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The rotarod test of motor coordination in mice was modified by increasing the rotation speed every 30 sec until the animals fell off. This procedure yielded a stable, proficient level of performance within four brief trials; the approximately normal distribution of performance times provided an equivalent measure of either improvement or impairment caused by drugs and permitted the use of parametric statistical tests. A total of 240 mice were assigned to 20 different groups of 12 each, administered oral doses of placebo or different drugs, prior to trial 4. The use of a ratio score (performance time in trial 4 divided by the same animal's time in trial 3) provided a measure of drug-induced changes, controlling for individual differences among animals in over-all level of performance. Two phenothiazines (chlorpromazine and perphenazine) impaired performance at low doses, with a progressively greater decrement at increasing doses (4, 8, 16 mg/kg); 2 barbiturates (pentobarbital and amobarbital) showed an all-or-none effect, with no significant decrement at the lower doses (20 and 40 mg/kg) but almost complete incapacitation at the highest dose of 80 mg/kg. Performance superior to the placebo condition was found with the 2 lower doses of pentobarbital and with 3 d-amphet-amine doses (4, 8, 16 mg/kg). An analysis of individual differences gave evidence that the animals which were inferior in prior performance were more susceptible to both improvement and impairment of performance under the influence of drugs.
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  • 9
    ISSN: 1432-2072
    Keywords: Central Nervous System ; Psychopharmacology ; DDT ; Parathion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The offspring of female mice treated with 2.5 mg/kg DDT during the second or third trimester of pregnancy showed a delayed acquisition of the conditioned avoidance response. If DDT was given in the first trimester, or if 3 mg/kg of Parathion was given during the pregnancy, no effect on the conditioned avoidance response of the off-spring was seen.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 12 (1968), S. 428-432 
    ISSN: 1432-2072
    Keywords: Ganglia, Basal ; Psychopharmacology ; Chlorpromazine ; Amphetamine ; Dopamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In rats micro-injections in corpus striatum of quaternary chlorpromazine and related drugs give rise to highly characteristic neuroleptic effects: antagonism of amphetamine-induced stereotyped behaviour and development of catalepsy. There is no effect of injections in hippocampus or septum. Dopaminergic mechanisms in corpus striatum seem to play a central role in neuroleptic action.
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 13 (1968), S. 161-169 
    ISSN: 1432-2072
    Keywords: Sleep-wakefulness Cycle ; Amphetamine ; Psychopharmacology ; Growing Animals ; Electrencephalography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. The effects of amphetamine on the sleep-wakefulness cycle were studied in 48 kittens during the growth period of 1–28 days of age. Recordings of EEG, EMG of the posterior neck muscles and respiratory rhythms were made as well as observations of gross behavior. 2. Percent time of wakefulness was increased with amphetamine (0.3 mg/kg). This effect became more marked with age, i.e., being more significant after 16 to 18 days of age (P〈0.005) than before (P〈0.05). These increases in the intensity of the effect during growth may be related to the postnatal development of the structures responsible for wakefulness. 3. Percent time of “activated” sleep was diminished significantly at all ages including the newborns (P〈0.005). This lack of the influence of age suggests that the structures responsible for “activated” sleep are well developed at birth. 4. The increase of percent time of slow wave sleep was observed. This increase is regarded as a “passive” manifestation of time left available after a severe diminution of “activated” sleep time and relatively slight increase of wakefulness time during amphetamine medication.
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 13 (1968), S. 210-221 
    ISSN: 1432-2072
    Keywords: Psychopharmacology ; Animal Behaviour ; Nicotine ; Physostigmine ; Motor Activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Rats of 3 strains were observed at regular intervals and their activity was recorded using four categories of behaviour-rearing, moving, grooming and immobile. Strain differences in control activity were found. Nicotine and physostigmine reduced the activity of the more active rats and increased that of the less active animals. Rearing behaviour was particularly susceptible to depression by both drugs. The similarity of effect of the two drugs supports the hypothesis that one of the actions of nicotine in the brain is the release of acetylcholine.
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 13 (1968), S. 287-298 
    ISSN: 1432-2072
    Keywords: Motion Pictures ; Motor Skills ; Eye Movements ; Psychopharmacology ; Psychological Tests
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Measures of skilled motor performances, both of a task-oriented (tests of eye-hand coordination) and incidental (control of facial and ocular muscles) nature were recorded for a sample of 20 healthy young adults before and after single administrations of perphenazine, opipramol, imipramine and placebo at doselevels commonly supposed to produce mood or behavioral effects. It was anticipated that such performances would be sensitive even to slight changes in the subjects' physiological and psychological state; the aim was to test the power of tests of subtle skills in providing indices of slight to moderate behavioral effects. The performance measures remained surprisingly little affected by all drugs, despite their sensitivity to drug-independent improvement in performance throughout the experimental day, and despite evidences of drug-related effects, especially for imipramine and opipramol, in simple objective physiological measures, and for imipramine alone in subjective measures taken concurrently. There may be a class of skilled sensory-motor acts, particularly those related to well-learned daily activities, which, rather than being vulnerable to adverse effect, remain efficient even in the presence of signs of disturbance of bodily function.
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  • 14
    ISSN: 1432-2072
    Keywords: Cannabis ; Lysergic Acid Diethylamide ; Mescaline ; Hallucinogens ; Psychopharmacology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Using climbing rope and bar-pressing behavior methods, rats were rendered tolerant to Δ 9-THC, cannabis extract, mescaline and LSD-25. Cross-tolerance experiments showed that rats refractory to Δ 9-THC and cannabis extract were still sensitive to mescaline and LSD-25, and vice-versa. These results suggest that, in spite of the similarity of the clinical symptoms produced in man by the 3 drugs, Δ 9-THC may have its psychotomimetic effects produced by different mechanisms from those of LSD-25 and mescaline.
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  • 15
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 37-45 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper illustrates the synthesis of nonlinear feedforward controllers for chemical reactors. In most of the theoretical development and application of feedforward control only linear systems have been considered. There are, however, no inherent linear limitations in feedforward control. Since chemical reactors are usually nonlinear, the effectiveness of control should be improved by including nonlinearities in the design of feedforward controllers. This is particularly true for batch reactors because of the large changes in variables during a batch cycle. Continuous stirred-tank reactors are studied with single and consecutive reactions of first and higher order. Effectiveness of linear and nonlinear feedforward controllers is compared for disturbances of various magnitude and direction. Feedforward control of batch and tubular reactors is also discussed.
    Additional Material: 5 Ill.
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  • 16
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 57-61 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of standing waves of controlled amplitude and frequency on the steady state rate of mass transfer through thin horizontal liquid layers is studied experimentally. The variables studied are the film thickness, the amplitude and frequency of the waves, and the spacing between the probes generating the waves. A bulk motion of complicated pattern known as drift is caused by the finite amplitude of the waves. The rate of mass transfer in the absence of imposed vibration is two to three times greater than that expected by molecular diffusion alone. Vibration increases the rate up to an order of magnitude or more, depending on the hydrodynamic conditions. The data at low frequencies are correlated by an expression of the form (i-io)/idiff = KAf3/4h1/2L-1/2.
    Additional Material: 6 Ill.
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  • 17
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 85-91 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A general method has been developed for controlling deterministic systems described by linear or linearized dynamics. The discrete problem has been treated in detail. Step-by-step optimal controls for a quadratic performance index have been derived. The method accommodates upper and lower limits on the components of the control vector.A small binary distillation unit was considered as a typical application of the method. The control vector was made up of feed rate, reflux ratio, and reboiler heat load. Control to a desired state and about a load upset was effected.Calculations are performed quite rapidly and only grow significantly with an increase in the dimension of the control vector. Extension to much larger distillation units with the same controls thus seems practical.
    Additional Material: 6 Ill.
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  • 18
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 235-241 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The extraction of lanthanum and barium from single falling drops of the uranium-chromium eutectic into magnesium was studied at 1,000°C. Because of the short contact times involved, the data best fit the stagnant diffusion model for lanthanum. For barium, the fraction extracted was governed by external resistance of the magnesium phase. Drop velocities were adequately represented by the Hu-Kintner correlation.
    Additional Material: 7 Ill.
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  • 19
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 260-265 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The external velocity field associated with the fall of a single drop through a quiescent liquid phase is discussed. The field responsible for the transfer of vorticity from the point of generation to the disperse phase is assumed to be almost identical with the field that transfers mass from the drop interface. The stream surfaces associated with this field are made visible by means of dye trails. Since the field is not amenable to mathematical formulation, and since many reports appear in the literature concerning correlations between measurable flow parameters and the physical properties of the system, the field configurations relative to mass transfer mechanisms are considered qualitatively. The delineation of the flow patterns behind the drop gives some indication of the manner in which the external flow contributes to the transfer coefficients.
    Additional Material: 11 Ill.
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  • 20
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 275-279 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper presents an investigation of the equations of motion to find the conditions under which these equations admit exact viscometric solutions for certain unsteady torsional flows of incompressible simple fluids. In general, for the cone and plane and the parallel disk geometries, curvilineal solutions do not exist for arbitrary members of the class of simple fluids; however, if the inertia terms can be neglected in the equations of motion, curvilineal solutions can be found for the complete class of simple fluids.
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  • 21
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 301-310 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper presents a theoretical study of the stability of chemical reaction on the external surface of a single spherical particle in stagnant surroundings. The analysis, which invokes methods of linear stability theory, yields necessary and sufficient conditions for stability of a steady state solution to small disturbances for the cases of very small and very large solid thermal conductivity. It is shown that heat losses from the solid surface may lead to transient behavior which is characteristically different from that for adiabatic surfaces, and that the unsteady state is strongly affected by the thermal capacity of the solid material. A numerical example is employed to illustrate the possible significance of unstable situations.
    Additional Material: 7 Ill.
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  • 22
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 311-317 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A comparison of the kinetic and diffusional models for solid-gas reactions occurring in a spherical particle is presented. The similarities and differences of the unreacted-core shrinking model and the homogeneous model are examined in light of the rate-controlling factors. In view of the similarity of the two models, it is shown that erroneous conclusions in regard to the mechanism and the activation energies may be drawn from an analysis of the experimental data. A more versatile model is presented in order to augment the two models so that wider varieties of solid-gas reaction systems may be treated. The concept of effectiveness factors in solid-gas reactions is introduced, and the influence of diffusion is ascertained.
    Additional Material: 8 Ill.
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  • 23
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 350-351 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 24
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 356-356 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 25
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 368-368 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 26
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 371-371 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 27
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 523-525 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 28
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 370-526 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 29
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 295-300 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In a previous paper, an analogy was presented which related the rise velocity of bubbles in liquids of infinite extent to the velocity of surface waves over infinitly deep liquids. In the present paper, a corresponding analogy is found which relates bubble velocities in bounded liquids to wave velocities over liquids of finite depth.
    Additional Material: 9 Ill.
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  • 30
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 392-397 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In gas-metal permeation, diffusion is normally considered to be the rate-controlling step. In addition, the diffusivity is usually taken to be independent of concentration. Under these conditions, the time lag (a characteristic of the system which depends on the time required to achieve steady state flow) is found to be (and theoretically should be) independent of the gas pressure applied to the inlet surface of the metal membrane. Furthermore, the time lag can then be directly related to the diffusivity of the system.In this paper, data on the hydrogen type 321 stainless steel system are presented which show a pronounced effect of pressure on measured values of the time lag. Taken alone, these data can be explained either by a concentration-dependent diffusivity or by resistance to flow at the metal surface. From steady state data it is shown that surface resistance is the better explanation. A model of the permeation process is presented which is consistent with the time lag data, and an estimate is made of the diffusivity of hydrogen in type 321 stainless steel.The variables studied were hydrogen pressure at the entrance surface of the membrane (0.1 to 30.0 atm.), temperature (300° to 800°C.), and membrane wall thickness (0.0252 to 0.2475 cm.).
    Additional Material: 3 Ill.
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  • 31
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    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 14 (1968), S. 415-420 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A packed bed model has been adopted to develop a general correlation applicable to the flow of Newtonian fluids through all types of woven metal screens. Both of the main theoretical approaches to studying pressure drop in packed systems have been used by visualizing the screen as a collection of submerged objects with surface area to unit volume ratio a for laminar flow, and as a bundle of tubes of diameter D for turbulent flow. In the usual manner viscous and inertial energy losses are added to give an expression for the total pressure loss. Rearrangement of the general equation to the form of a friction factor yields a unique definition of the Reynolds number for screens NRe = ρu/μa2D. Procedures are described for collection of pressure drop-velocity data for the flow of nitrogen and helium through plain square, full twill, fourdrinier, plain dutch, and twilled dutch weaves. The data are used to derive a viscous resistance coefficient α = 8.61 and an inertial resistance coefficient β = 0.52. The validity of the correlation equation is tested by using additional data from the literature. The correlation successfully predicts pressure drop for a Reynolds number range of 0.1 to 1,000, void fractions from 0.35 to 0.76, screen pore diameters from 5 to 550 μ, mesh sizes from 30 to 2,400 wires/in., and surface area to unit volume ratios from 1,200 to 29,000 ft.-1.
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  • 32
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    AIChE Journal 14 (1968), S. 352-352 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
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  • 33
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    AIChE Journal 14 (1968), S. 357-357 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 34
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    AIChE Journal 14 (1968), S. 363-363 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 35
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    AIChE Journal 14 (1968), S. 372-379 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pool nucleate boiling heat transfer curves for pure nitrogen, oxygen, argon, methane, and carbon tetrafluoride have been measured on a horizontal, flat, circular, platinum plated disk for saturation pressures ranging from 1 atm. or less to the immediate vicinity of the critical pressure for each liquid. The results have been compared with various suggested nucleate boiling correlations, and the correlations of McNelly, of Kutateladze, and of Borishanskiy-Minchenko are found to be roughly equally successful and all distinctly superior to those of Rohsenow, of Gilmour, and of Forster and his collaborators for these liquids. For oxygen, argon, methane, and carbon tetrafluoride, boiling hysteresis of a type not previously reported was observed at intermediate and high saturation pressures on this surface.
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  • 36
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    AIChE Journal 14 (1968), S. 388-391 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The movement of solids associated with the rise of a single gas bubble in an incipiently fluidized bed has been determined. The bulk volume, measured at the porosity of incipient fluidization, of tracer solid which is transported across the original interface between undyed glass spheres in the upper region and dyed glass spheres (tracer solid) in the lower region, is approximately 30% of the bubble volume. The measurements relate to bubble volumes from 14 to 200 ml. in a glass column, 4 in. diam. Solids used were glass spheres of diameter 380 μ. The profile created when a bubble rises through a layer of fluidized tracer solids into the fluidized solids above the tracer layer has been approximately determined. The distance by which the solids were displaced upward, due to the passage of the bubble, was found to be greater than would have been the case if the behavior were that of a sphere in an inviscid liquid.
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  • 37
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    AIChE Journal 14 (1968), S. 411-414 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The profile of a growing droplet was determined with a pressure balance which was similar to that derived by Laplace for the static droplet. An additional term was added to the balance to account for the pressure on the interface due to the motion of the fluid within the droplet. The entire pressure balance was then combined with differential equations describing the geometry of the droplet. Computed profiles compared favorably with those obtained experimentally.An additional result was the definition of a parameter, f, indicating the importance of internal fluid motion on the shape of the profile. A method of estimating this parameter without solving the equations was developed.
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  • 38
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    AIChE Journal 14 (1968), S. 426-434 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A Bench-scale size fluidization system was constructed for the purpose of conducting experiments to determine density and pressure fluctuations in gas fluidized beds. Density fluctuations and bubble sizes were measured with a photocell device and β-ray absorption. Pressure fluctuations were determined with a conductivity cell. The frequency distributions of the density and pressure fluctuations and bubble sizes were determined as functions of several variables. They could be described by dimensionless coefficients and X2-distributions with different degrees of freedom. Such variables as distance from the gas distribution plate, bed height, particle size, gas flow rate, and internal screens were considered.
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  • 39
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    AIChE Journal 14 (1968), S. 421-425 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dialysis of binary aqueous solutions of several sugars through a cellophane membrane was studied in a stirred batch dialyzer. Sherwood numbers describing mass transfer resistance in the fluid adjacent to the membrane were determined as a function of the corresponding Reynolds and Schmidt numbers. The results establish a reproducible environment for membrane testing in which a known controllable and small interfacial resistance is placed in series with that of the membrane. The results are also shown to support, for this geometry, the postulation of a third power relationship between eddy diffusivity and dimensionless distance from the phase boundary as well as the Sherwood-Ryan nondimensionalization of this distance.
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  • 40
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    AIChE Journal 14 (1968), S. 458-467 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A method is developed for predicting rates of gas absorption into laminar rippling films in terms of the surface velocities. The description is an extension of the surface-stretch model of mass transfer (1) and is therefore useful for cases of high Peclet number. The description can be used with any of the presently known hydrodynamic models of rippling films and with any future models which may be developed, provided they satisfy two relatively nonrestrictive conditions: (1) the ripples are of a two dimensional nature, being of constant thickness in the direction normal to their direction of propagation, and having no velocity components in this transverse direction; and (2) the ripples propagate at constant celerity and with constant shape. It can be used for both traveling and standing waves and can be extended to describe the effects of high net-mass transfer rates and combined diffusion and chemical reaction.
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  • 41
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    AIChE Journal 14 (1968), S. 473-479 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experimental data and a mathematical model for the dehydrogenation of cyclohexane on a platinum-on-alumina catalyst in the presence of excess hydrogen are presented. Differential rate data were obtained by using a fixed bed flow reactor over a temperature range of 400° to 500°C., and a pressure range of 21.3 to 41.8 atm. at modified Reynold's numbers of 20 to 65. Cyclohexane concentration was varied from 16 to 25 mole %. In the development of the basic model, complete transport control of the overall reaction rate with equilibrium at the fluid external surface interface is assumed. The average deviation between experimentally determined and basic model calculated rates was 5.65%.Modification of the model by replacing the equilibrium assumption by a crude surface rate expression resulted in a reduction in average deviation to 4.3% and the maximum deviation was reduced from 22 to 12%.
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  • 42
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    AIChE Journal 14 (1968), S. 490-496 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A finite difference method combined with the quasilinearization technique is used to solve the nonlinear two-point boundary value problems. This method does not have the stability problem connected with the marching integration techniques. A scheme which can be used to reduce the rapid access memory requirements of digital computers is also proposed. The steady state equations resulting from mass and energy balances in a tubular reactor with axial diffusion are solved by this method. With very poor initial approximations, only three to seven iterations are needed to obtain the correct answer.
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  • 43
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    AIChE Journal 14 (1968), S. 650-650 
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    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 44
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  • 45
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    AIChE Journal 14 (1968), S. 658-659 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 46
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    AIChE Journal 14 (1968), S. 661-662 
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    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 47
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    AIChE Journal 14 (1968), S. 666-667 
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    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 48
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    AIChE Journal 14 (1968), S. 671-673 
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    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 49
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    AIChE Journal 14 (1968), S. 673-673 
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    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 50
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    AIChE Journal 14 (1968) 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 51
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Various modifications of the Prandtl mixing-length model for turbulent momentum transport in pipes and between parallel plane walls are discussed. The most complete modification, due to Gill and Scher, is improved by replacing one of their two empirical constants by a theoretically calculable parameter. The new theory is compared with experimental data from the literature and found to reproduce frictional resistance data accurately for all values of the Reynolds number. It is somewhat in error for velocity profiles at high Reynolds numbers, but accurately reproduces velocity profile data in the transition region. The new theory represents the first accurate semi-theoretical calculation of frictional resistance coefficients for all regimes of flow (laminar, transitional, and turbulent) for both pipes and parallel plane ducts, and of velocity profiles in the transitional flow regime in either geometry.
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  • 52
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    AIChE Journal 14 (1968), S. 703-708 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An analysis of oxygen absorption by blood flowing through a small oxygen-permeable fiber in steady state laminar flow is presented. The rigidity and geometry of the fibers eliminate unpredictable shunting and distention, permitting a more detailed analysis of blood-membrane factors than has previously been undertaken. The mathematical analysis treats the blood as a homogeneous, non-Newtonian fluid with a reversible nonlinear oxygen sink (erythrocytes). The differential equations are solved numerically and the results of the parametric analysis are presented. The parameters that have a major influence on residence time necessary to obtain a specified oxygen content are the Grashof number, the concentration of hemoglobin in the blood, and wall Nusselt number, γ: γ = DLαL/DMαM In [1 + tm/R] where D = diffusion coefficient, α = Bunsen solubility coefficient, subscript L = liquid in tube, subscript M = tube material, R = inner radius of tube, tm = tube wall thickness.Comparison of the experimental results to the model indicate that mixing due to the heterogeneous nature of blood is minimal and that the major limitation in oxygen absorption is the blood film. Means of reducing this resistance are discussed.
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  • 53
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    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 54
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    AIChE Journal 14 (1968), S. 866-869 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A study was made to evaluate pulses as a forcing function on a 24-plate distillation column. Pulses of two shapes, rectangular and displaced cosines, and of different widths were used as inputs to the reflux return line from the condenser to the column. The effect of the disturbance was a change in the liquid return rate which correspond to the shape and size of the pulse. The output responses of the system were temperatures measured at different times and at different plates in the column.Bode diagrams were plotted from the experimentally determined data. From these plots, it was determined that the system could be approximated by linear first-order equatons. The time constants for the linear system were determined both by direct sinusoidal forcing and by pulse forcing. Pulse data were considered acceptable when the values of the time constant and the phase angle determined by the pulse compared favorably with those determined by steady state sinusoidal forcing.
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  • 55
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    AIChE Journal 14 (1968), S. 903-908 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Free convective effects on forced convective mass transfer in the Stokes flow region were studied experimentally by using a single drop in a liquid-liquid system.Liquids used to form the drops were methyl acetate or 2-ethoxyethyl acetate with distilled water as the continuous medium. Spherical drops were formed on the capillary tip of a 0.58 cm. O.D. capillary glass tube centered in a 2.5 cm. O.D. pyrex tubular flow cell.Results are presented graphically as NSh vs. NPe, NSh vs. NRe, and NSh/NRa1/4 vs. NPe to show the variation of mass transfer with flow rate and free convection. The range of variables was 10 ≤ NPe ≤35,000; 0.1 ≤ NRe ≤ 30; 578 ≤ NSc ≤ 1,149; and 12.3 ≤ NGr ≤ 75.7.Satisfactory comparisons were also made with other investigators' findings.Results substantiate that at low flow rates (Reynolds number 〈 10, Peclet number 〈 1,000) free convective effects either reinforce or interfere with mass transfer. This interference takes place until flow becomes high enough to overcome interfering effects of free convection.
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  • 56
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    AIChE Journal 14 (1968), S. 934-939 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: If the transient equations of a plug flow tubular reactor are transformed into a set of corresponding ordinary differential equations, stability information for the former may be obtained graphically from knowledge about the transients of the latter. The analysis presented in this paper combines this simplification with the definitions and theorems of Weiss and Infante to propose a method of direct computation whereby transient bounds may be found for this important class of distributed-parameter chemical reactor systems.
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  • 57
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    AIChE Journal 14 (1968), S. 813-813 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 58
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    AIChE Journal 14 (1968), S. 946-955 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper presents the cause of instabilities which arise during the numerical solution of ordinary differential equations. By using the numerical integration routines presently available, one actually approximates the differential equation by a difference equation. If the difference equation is of a higher order than the original differential equation, the approximate solution contains extraneous solutions which are not at all related to the true solution. It is the behavior of these extraneous solutions that one is usually concerned with in a stability analysis.Also presented is a procedure for obtaining a bound on the largest allowable integration step size for a class of chemical engineering problems. A detailed explanation of the procedure is illustrated for unsteady state distillation calculations.
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  • 59
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    AIChE Journal 14 (1968), S. 966-969 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 6 Ill.
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  • 60
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    AIChE Journal 14 (1968), S. 977-979 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 61
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    AIChE Journal 14 (1968), S. 986-988 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 62
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    AIChE Journal 14 (1968), S. 762-771 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new method for determining adsorption equilibrium constants, rate constants, and intraparticle diffusivities is described and applied for the adsorption of ethane, propane, and n-butane on silica gel. The method rests upon recently developed theory for relating the moments of the effluent concentration wave from a bed of adsorbent particles to the rate constants associated with the various steps in the overall adsorption process. It is necessary to operate at concentrations of adsorbable gas such that the adsorption isotherm is linear. However, it is possible to take into account effects of longitudinal dispersion and diffusion to the particle surface as well as the intraparticle processes of diffusion and adsorption on the pore surface.The method gave reasonable values for intraparticle diffusivities and adsorption rate constants. Intraparticle diffusion was a major resistance for all particle sizes studied and for the largest size (R = 0.50 mm.) this step controlled the overall rate.From the constants determined chromatographically it is possible to predict breakthrough curves for the adsorption of these hydrocarbons on silica gel. The predicted curves agree well with experimentally established breakthrough curves.
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    AIChE Journal 14 (1968), S. 805-806 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Additional Material: 3 Ill.
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    AIChE Journal 14 (1968), S. 809-811 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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    AIChE Journal 14 (1968), S. 816-817 
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    Keywords: Chemistry ; Chemical Engineering
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  • 66
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    AIChE Journal 14 (1968), S. 825-826 
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    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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    AIChE Journal 14 (1968), S. 835-836 
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    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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    AIChE Journal 14 (1968), S. 886-895 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new method, based upon chromatography, was used to measure surface diffusion coefficients for ethane, propane, and n-butane on silica gel. The diffusivities correspond to very low surface coverages (fraction of a monolayer of the order of 10-4) and hence should represent limiting values. A survey of available surface diffusion information, all at higher coverages, indicated that the results reported here are at the lower end of the range of diffusivities. The activation energy and heat of adsorption, for example, for n-butane, were 4.4 and -7.8 k cal./mole, respectively.Surface diffusion was a significant fraction of the total intraparticle mass transport, in part because in the small pores in silica gel gas phase diffusion was solely by the Knudsen mechanism. For propane, surface migration was 73% of the total transport at 50°C. and 61.5% at 125°C.
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    AIChE Journal 14 (1968), S. 917-922 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A study has been made of the expansion characteristics of beds of uniformly sized spherical particles of lead, nickel, sand, glass, and plastic that have been fluidized with air, carbon dioxide, and helium in columns packed with open-ended cylindrical screen packing. The addition of packing to a gas-fluidized bed limits the bubble size, prevents slugging and allows beds of high aspect ratio to expand smoothly in a manner similar to the behavior of liquid-fluidized beds. Moreover, much of the experimental data for gas-fluidized screen-packed beds have yielded straight lines on a Richardson-Zaki type of plot, again similar to the expansion of liquid-fluidized beds. The conditions necessary for this pseudoparticulate behavior in packed gas-fluidized beds are discussed. A correlation, based on the analysis given by Richardson and Zaki for liquid-fluidized beds, is proposed to relate bed porosity with gas velocity, density and viscosity, particle size and density, and bed diameter.
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  • 70
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    AIChE Journal 14 (1968), S. 939-946 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Convective diffusion in laminar flows which develop from rest and in the velocity entrance region of tubes, is studied. Criteria for the validity of the simple dispersion model are established by comparison of analytical results with numerical experiments.It is found that the extent of dispersion is less in developing velocity fields than in those which are fully developed. This occurs because dispersion is enhanced by differences in the velocity of the fluid particles on a plane perpendicular to the main direction of flow. Such differences are greatest when the flow is fully developed.
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  • 71
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    AIChE Journal 14 (1968), S. 956-961 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A theoretical study was made of transient diffusion to a body immersed in a finite volume of well-stirred fluid. The major contribution of this work was the development of a technique for solving the problem for a three-dimensional body of arbitrary shape. The solutions are in a form that is useful for determining diffusion coefficients insolids by means of the constant-volume experimental technique.The partial differential equation coupled with the ordinary differential equation describing the diffusion process is transformed into a single integral equation in terms of the solute concentration in the reservoir. A numerical technique is then presented for solving the integral equation. Numerical solutions were computed for the three geometries that possess analytical solutions: the infinite slab, the infinite cylinder, and the sphere. By properly choosing the step-size numerical results were easily obtained that agreed with the exact solution to four decimal places.New solutions were computed for two three-dimensional geometries: the finite cylinder and the rectangular prism. A range of shape factors and ratios of the volume of the reservoir to that of the solid body were employed for each geometry. It was shown that by selecting the ratio of volume to external surface area as the characteristic length of each shape object, the solutions for all shapes were brought close together and were identical during the initial part of the transient.
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  • 72
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    AIChE Journal 14 (1968), S. 973-975 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 73
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    AIChE Journal 14 (1968), S. 983-983 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 74
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    AIChE Journal 14 (1968), S. 993-993 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 75
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    AIChE Journal 14 (1968), S. 118-122 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Empirical size-dependent growth rate models are studied for their effect on the population density distributions from a continuous, mixed suspension, mixed product removal (CMSMPR) crystallizer. The growth rate models and/or their corresponding population density distributions are examined for continuity, convergence of moments, versatility, and their ability to fit experimental data.A new empirical size-dependent growth rate model is proposed which has properties superior to those of previous models. Experimental steady state data are presented to illustrate the application of the model to actual CMSMPR crystallization systems.
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  • 76
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    AIChE Journal 14 (1968), S. 135-144 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A critical discussion is given of the use of local compositions for representation of excess Gibbs energies of liquid mixtures. A new equation is derived, based on Scott's two-liquid model and on an assumption of nonrandomness similar to that used by Wilson. For the same activity coefficients at infinite dilution, the Gibbs energy of mixing is calculated with the new equation as well as the equations of van Laar, Wilson, and Heil; these four equations give similar results for mixtures of moderate nonideality but they differ appreciably for strongly nonideal systems, especially for those with limited miscibility. The new equation contains a nonrandomness parameter α12 which makes it applicable to a large variety of mixtures. By proper selection of α12, the new equation gives an excellent representation of many types of liquid mixtures while other local composition equations appear to be limited to specific types. Consideration is given to prediction of ternary vapor-liquid and ternary liquid-liquid equilibria based on binary data alone.
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  • 77
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    AIChE Journal 14 (1968), S. 77-84 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Locally linearized equations for dynamic disturbances from a steady state have been solved analytically for an adiabatic chemical reactor with chemically inert packing and a homogeneous chemical reaction. The solutions, in the form of transfer functions, include the effects of heat capacity of the packing and heat transfer between the packing and the fluid, as well as the coupling effects of chemical reaction and the associated heat generation.Several limiting cases of the transfer functions are discussed and the transfer functions are simplified by an approximation of the temperature dependence of the reaction rate. Frequency responses and step responses of the reactor are calculated from the transfer functions.
    Additional Material: 8 Ill.
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  • 78
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    AIChE Journal 14 (1968), S. 169-173 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: One of the greatest difficulties in the analysis of mixing operations for powders is that of specifying the degree of mixedness in a quantitative manner. This problem is studied for on idealized model. A precise index of the degree of mixing is found for this model, which holds promise of being useful for real mixtures. It is shown that samples of a single size provide all the necessary information. The effect of sample size is defined quantitatively, and a minimum sample size is recommended.
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  • 79
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    AIChE Journal 14 (1968), S. 32-37 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Inequalities are derived for a general class of convex-functional means which may contain negative weights. Specific cases include the arithmetic-mean-geometric-mean inequality and other power-mean inequalities. These inequalities make possible the solution of a wider class of extremum problems than are susceptible to the classical means with positive weights. In particular, it is shown that the geometric programming algorithm may in some cases be extended to functions with negative coefficients. A weaker result is derived for application without restrictions on the signs of the coefficients or variables. This leads to a computational scheme which is useful in the solution of certain classes of nonlinear programming and inequality-constrained multistage optimization problems.
    Additional Material: 2 Ill.
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  • 80
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The selective, highly endothermic reaction of methylcyclohexane to toluene and hydrogen was studied experimentally over a commercial Pt/Al2O3 catalyst, in an electrically heated tube serving as a packed-bed reactor heat exchanger. The constant-flux reactor, with measurement of temperatures within the bed at points intermediate along its length, proved well suited as an integral reactor for providing information on the reaction rate. A simple analytical model of the reactor was developed, and some of the data were used with the model to derive a rate expression.The model gives a good representation of radial variation of temperature in the packed bed. In the region of high Reynolds numbers investigated, radial transport of enthalpy is described in the model by a film resistance at the tube wall defined by heat transfer coefficient, and a diffusive transport through the packing, dominated by eddy diffusion.
    Additional Material: 9 Ill.
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  • 81
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An approximate theory for transient dispersion with combined free and forced convection in vertical tubes is developed and tested experimentally. It is found that the dispersion coefficient in such systems depends on a parameter α, which is defined by Equation (38). The analytical expression developed for the dispersion coefficient, Equation (33), is found to be a reasonably good approximation in the range -50 〈 α 〈 300.Experimental results are reported for a rather wide range of parameters for tubes with both 1 1/2 and 5 mm. diameters.It is found that the extent of dispersion is enhanced significantly when lighter fluid is on the bottom and displaces a heavier one. On the other hand, the dispersion coefficient is inhibited when the situation is reversed. It is found that these effects are not symmetrical with respect to the absolute magnitude of the parameter α as is illustrated in Figure 12.
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  • 82
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    AIChE Journal 14 (1968), S. 123-127 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The theoretical equations for the flow of Newtonian fluids in a falling cylinder viscometer with eccentricity are developed. The error in fall velocity of the cylinder caused by eccentricity is determined and presented in tabular form. An approximate method to determine the error in fall velocity caused by eccentricity for non-Newtonian fluids of the power law type is also presented. For the Newtonian case, n=1, the approximate method is shown to give excellent agreement with the exact method.
    Additional Material: 3 Ill.
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  • 83
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A correlational procedure was developed to predict the vapor liquid equilibrium behavior of light hydrocarbons in heavier hydrocarbon solvents at low temperatures and elevated pressures. The method is applicable to paraffinic as well as aromatic solvents.The method employed the Benedict-Webb-Rubin equation of state to predict the vapor phase fugacities. Methane liquid fugacities in the various hydrocarbon solvents were based upon Henry's law which included terms to account for compositional and pressure effects. The liquid fugacities for ethane and propane were calculated using infinite dilution data to modify empirically the Scatchard-Hildebrand equation. Excellent agreement between the correlated and low-temperature data available on this class of systems was obtained.
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  • 84
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    AIChE Journal 14 (1968), S. 159-164 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The intrinsic kinetics of the hydrogenolysis of thiophene on a cobalt molybdate catalyst were studied in a differential reactor with recirculation, at a total pressure of about 1 atm. and temperatures of 235° to 265°C. Retardation of the reaction by both thiophene and hydrogen sulfide was significant and the rate of thiophene disappearance was correlated by a Langmuir-Hinshelwood type of kinetic equation. Hydrogenation of the butene intermediate was inhibited by both butene and hydrogen sulfide and the rate of this reaction was also described with a Langmuir-Hinshelwood rate equation. The forms of the kinetic expressions obtained imply that the butene is not hydrogenated at the original desulfurization site.
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  • 85
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    AIChE Journal 14 (1968), S. 173-180 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 86
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    AIChE Journal 14 (1968) 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 87
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    AIChE Journal 14 (1968), S. 210-364 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 88
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    AIChE Journal 14 (1968), S. 211-221 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This work is a study of the stability of a batch fluidized bed with a simple model. It is shown that multiple steady states can occur with all catalyst particles at the same temperature, some of these states being unstable. If the initial temperature of all the particles is not the same, a special kind of steady state, in which particles of different temperatures can coexist in the bed, might be obtained. The number of these pathological steady states is not finite, and the conversion obtained may be very different from that obtained by a uniform steady state.The analysis has demonstrated that the initial temperature of the catalyst particles may be a predominate factor in determining the kind of steady state obtained. For the case of uniform catalyst particles, a simple stability analysis has been developed. Several numerical solutions of the transient equations were performed to investigate the possible responses of the system to disturbances of various steady states.
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  • 89
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    AIChE Journal 14 (1968), S. 242-244 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 90
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    AIChE Journal 14 (1968), S. 266-274 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An apparatus and experimental technique were developed for the study of the kinetics of relatively rapid reaction and subsequent crystallization in condensed phases. The method employs batch experiments to establish the integral of crystallization rate over ranges of pertinent external variables.The crystallization of potassium dipicrylamine from aqueous solution, a system of potential interest in application to potassium recovery from brines, was studied experimentally. It is shown that both reaction and crystallization rate parameters may be determined from the data on the basis of the consecutive rate model developed; application of the Burton-Cabrera-Frank theory of crystal growth to this system is demonstrated.
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  • 91
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    AIChE Journal 14 (1968) 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 92
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 93
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    AIChE Journal 14 (1968), S. 286-294 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A rigorous analysis of jet hydrodynamics is used to develop a technique for determining diffusion coefficients from laminar liquid jet absorption experiments, and the influence of the jet fluid mechanics on the absorption process is clarified. The new technique is used to determine the diffusivities of carbon dioxide, oxygen, argon, nitrous oxide, ethylene, and propylene in water within the temperature range 25° to 40°C.A critical analysis of available diffusivity data for these gases indicates that there is no conclusive evidence that demonstrates the existence of a significant interfacial resistance in uncontaminated laminar jet experiments. In addition, comparison of existing data shows that the commonly accepted diffusivities for the oxygen-water system may be significantly higher than the actual values. It is concluded that the laminar jet experiment is a rapid, accurate method of obtaining diffusion coefficients of dissolved gases in liquids.
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  • 94
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    AIChE Journal 14 (1968), S. 325-330 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 7 Ill.
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  • 95
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    AIChE Journal 14 (1968), S. 331-334 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The characteristics of cylindrical particles settling in the Stokes regime in a bounded fluid are discussed. Applicable theory is reviewed and experimental data showing the effect of orientation on the terminal velocity are presented.
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  • 96
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    AIChE Journal 14 (1968), S. 351-351 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 97
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    AIChE Journal 14 (1968), S. 448-452 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The concept of a continuous mixed suspension-mixed product removal crystallizer was used both as an analysis and experimental tool to study the effects of suspension density on crystal size distribution. If the crystals present in suspension are not a source of nuclei, larger crystals will be obtained in the presence of higher suspension densities. If the rate of new particle formation is proportional to the amount of crystals present, the crystal size obtained will not be changed by the suspension density level. There was evidence of nucleation rate dependency on the quantity of suspended crystals in the two systems studied experimentally.
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  • 98
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    AIChE Journal 14 (1968), S. 452-457 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The nucleation kinetics of three materials were related to the growth kinetics using steady state data obtained at various degrees of supersaturation. The power models obtained from the three crystallizaitons exhibited widely different kinetic orders. These materials were then crystallized under unsteady state conditions in a mixed suspension-mixed product removal crystallizer and the transient size distributions were determined. The unsteady state model previously developed by Randolph and Larson was solved on a digital computer for the three systems. Good agreement was obtained. It was found that unsteady state experiments have some advantages over steady state experiments in determining the kinetic order of nucleation.
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  • 99
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    AIChE Journal 14 (1968), S. 497-499 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 100
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    AIChE Journal 14 (1968), S. 499-501 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
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