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  • Articles  (3,413)
  • Animals  (1,937)
  • Industrial Chemistry  (1,476)
  • 1985-1989  (2,109)
  • 1950-1954  (1,304)
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  • Articles  (3,413)
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  • 1
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Liquid-liquid direct-contact heat transfer in a spray column was studied numerically for a low hold-up. The solutions of the conservation equations of mass, momentum and energy for both phases agree well with earlier experimental results, if one assumes a rigid liquid-liquid interface. Heat transfer inside is dominated by transient conduction and natural convection. It was found that the Nusselt number for free convection depends essentially only on the Rayleigh number.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 374-378 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Wall shear rate vectors in a bubble column and an airlift-loop reactor were measured using the limiting-current electrodiffusion technique. In connection with a new circular three-segment probe, the magnitudes and directions of shear rates were determined. The results for the bubble column are in good agreement with hot film-anemometry measurements in the same column. Moreover, the spiral flow structure, postulated in the shear-zone model of Franz, has been confirmed. In addition, the measuring technique was used to determine the flow structure in an airlift-loop reactor employed for the cultivation of animal cells. The region above the gas distributor of this fermenter has been identified as critical for mechanical damage to the cells.
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  • 3
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fermentation under modified gravity could be of interest in application to (a) increasing productivity of growth and growth linked production with microorganisms at high cell densities and (b) increasing the productivity of highly viscous pseudoplastic polysaccharide fermentation. In both cases, higher oxygen transfer rates in centrifugal fields result in higher productivities since these fermentations are usually oxygen limited. A further aspect of fermentation under increased gravity is the reduction of foam since foam coalescence time decreases with acceleration number. On the other hand, under microgravity, shear reduction would allow growth and production even for very shear sensitive organisms. In order to carry out fermentations under modified gravity, a special type of fermenter-the centrifugal field bioreactor CFBR-has been developed at the Institute of Chemical Engineering (Head: Prof. Mersmann) of the Technical University of Munich. For the first time, exoprotein biosynthesis of lipase with S. carnosus has been carried out under sterile and controlled conditions in this novel bioreactor, in presence of increased mass forces.
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  • 4
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An experimental technique and evaluation method is described for the determination of local heat transfer coefficients in tubes or other ducts. By means of a rotary mixing valve, cold and warm fluid flows are mixed in order to generate an arbitrarily shaped but periodically oscillating inlet temperature profile at the test tube. The propagation of the fundamental harmonic oscillation from the fluid to the outer surface of the tube wall is calculated analytically. Comparison of fluid and wall oscillations yields the heat transfer coefficient to be measured. The inaccurate measurement of fluid bulk temperature in the centre of the cross-section is compensated by an additional correction. Experiments were carried out with turbulent water flow through a copper tube. Measured heat transfer coefficients were compared to values calculated using Hausen's equation and good agreement was obtained.
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  • 5
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    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 395-399 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Mean droplet diameter of the dispersed phase in pulsed plate extraction columns was measured for binary and ternary systems. A change in the droplet size in the presence of solute, dependent on such factors as the direction of mass transfer, droplet size in the binary system, radio of diffusion coefficients, viscosity of the continuous phase, interfacial tension and driving force for extraction was observed. Two new empirical correlations of mean droplet sizes in mass transfer conditions are proposed. These correlations have been successfully applied to other extraction columns.
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  • 6
    Electronic Resource
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    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 406-413 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: During molecular distillation in a falling film apparatus, temperature and concentration of the more volatile components undergo a marked decrease in axial and radial directions, due to the distillation in vacuo. The gradients produce changes in the rate of surface evaporation and separation efficiency along the flow path. A theoretical study of this problem is presented for binary mixtures. The respective differential equations for heat and mass transfer in the liquid film are solved numerically. As the results demonstrate, the aspect ratio of an apparatus should be large when a high separation is required and small when a high distillation rate is more important.
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  • 7
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Flow phenomena, local heat and mass transfer and pressure drop of corrugated passages in process equipment are examined. Based on a method for measuring local heat and mass transfer, developed in previous investigations, a procedure has been formulated for the determination of local heat and mass transfer in corrugated passages. Using the analogy between heat and mass transfer, this technique allows the determination of heat transfer distributions in any structures with high local resolution. The corresponding pressure drop is presented together with the local and integral heat and mass transfer of different structures. It is shown that differences in heat and mass transfer as well as in pressure drop are due to different flow phenomena which also characterize mixing behaviour.
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  • 8
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Crystallizer design has to take into account the physical and chemical properties of the solution and solids as well as the geometry, type and operating conditions of the crystallizer. The most important property of a crystallizing system is its solubility. High solubility leads to low relative supersaturation and large mean crystal size, and vice versa. High solubility systems can be sensitive to abrasion and attrition. For low solubility systems, mixing is crucial.
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  • 9
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    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 419-426 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper considers the dynamic performance of instruments in control systems. Errors connected with transient measurements are discussed. It is shown that it is not always proper to assign common statistical properties to these dynamic errors. Emphasis is placed on temperature sensors. Common industrial thermometers are described and factors affecting their response discussed. An a-priori dynamic performance prediction procedure is presented. This permits preinstallation estimation of response characteristics of sensors used in industrial processes. Sensors in service also require performance assessment since they can deteriorate with use. In-situ testing is useful for this purpose and a recently develolped procedure is described.
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  • 10
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Modelling of the kinetics of a 20-N hydrazine thruster is carried out by considering two different heterogeneous reaction channels for hydrazine decomposition to the intermediate ammonia. The parameters of the reactor model are estimated by making use of temperature profiles at the wall of the decomposition chamber. Simulated ageing of the catalyst revealed an increase of the rate of deactivation with increasing total firing time.
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  • 11
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The principle of ultrasonic spectrometry is based on the measurement of the ultrasonic extinction caused by the presence of particles. From measurements at different frequencies and with the knowledge of the ultrasonic extinction cross section of the particles, a system of linear equations can be established and solved to obtain the particle size distribution and particle concentration. With an experimental apparatus covering the frequency range from 1.7 MHz to 81 MHz, particles ranging from 20 to 1000 μm in diameter may be analyzed. The measurements can be carried out with particle concentrations as high as 10% by volume.
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  • 12
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The “nozzle scrubber” is a wet scrubber in which the scrubbing water is dispersed in dust laden gas stream by means of one or more pneumatic nozzle. This scrubber is distinguished by an excellent collection efficiency for submicron dust at an unusually low energy and water consumption. So far, the physical effects affecting the separation cannot be explained by a well-defined theory. Therefore, it is sensible to investigate the collection efficiency with regard to the mechanisms of inertial impaction, turbulent diffusion and coalescence induced by turbulence. The experimental equipment is of a very simple design. A light scattering device was used to measure the particle distributions. In addition, electron micrographs were analyzed to obtain information about the submicron particles. The influence of operating parameters on grade efficiency has been demonstrated by their systematic variation. The contribution of turbulent diffusion to the collection efficiency has been confirmed; nevertheless, grade efficiencies were also measured when inertial impaction prevailed.
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  • 13
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This study describes the gas and liquid distributions in a column with structured packings. The column is 0.5 m in diameter. It is equipped with a total of 1289 detectors in the top and bottom cross-sections. These detectors provide a detailed picture of the gas and liquid flows through elements of only 25 × 25 mm2. The maldistribution in the gas bulk flow is negligible. Only the observed wall can contribute to malperformance. The gas flows in parallel to sheet orientation, thus introducing a radial transport. Together with the change in the orientation of subsequent packing elements, this results in good gas mixing. It was observed that the liquid wall flow rate decreases when the gas velocity exceeds 1.7 m/s. Up to the loading point, the maldistribution of the liquid is constant. Above this point, the equality of the distribution deteriorates rapidly, due to the occurrence of large-scale liquid segregation.
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  • 14
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    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 235-244 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Film theory under consideration of one-sided diffusion is a satisfactory basis for the calculation of vapour condensation from a flowing turbulent mixture with non-condensable gases. At atmospheric pressure and low condensate flow rates, coefficient equations for smooth tubes are used as a rule. At higher pressures and thus, at higher temperatures and gas densities, there are additional parameters. For instance, non-ideal behaviour of the gas phase or the surface roughness affects the condensation process. These parameters were examined in a test plant under variation of pressure, steam concentration and temperature in a vapour/air mixture. At pressures of up to 21 bar, the Reynolds number of the gaseous phase reaches a maximum value of 128 000 and of 720 for the condensed phase. After description of the test facility, the experimental results are explained and discussed. It is shown that the experimental results are not in a good agreement with the common calculating methods. Taking into account the non-ideal behaviour of the steam/air mixture and the roughness of condensate surface by using a friction factor ξr, all the results could be calculated with an accuracy of ± 20%. This was achived with a modification of the coefficient equation of Gnielinski [1] and by using the equation of Andreussi [2] for the friction factor of a cocurrent annular flow. With respect to one-sided diffusion, the film theory is still applicable. The described method for the determination of local transfer coefficients includes the common calculating method. It represents an extension of the general validity of the film theory.
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  • 15
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    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 245-248 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Mass transfer data are presented for absorption of oxygen in a centrifugal film apparatus. The apparatus was designed to exclude the formation of foam by gas dispersion in liquid. Cells and micro-organisms are not subjected to high shear stress. Therefore, this equipment can be applied in fermentation processes. In the present work, experimental data and correlations were obtained on splitting of the liquid film and oxygen absorption into the film through a spiral ridge formed on the conical surface. The performance of the apparatus is found to be equivalent to those of other types of absorbers.
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  • 16
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    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 249-254 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Thermally stabilized combustion has a number of unique characteristics which permit the generation of steam or other forms of process energy from the heat of combustion of a gaseous or clean liquid fuel in remarkably compact, integrated apparatus while truly minimizing the concentrations of NOx, CO and unburnt fuel in the effluent. These characteristics, which have been identified by a long-range program of research, are described and the advantages and limitations of this process are discussed.
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  • 17
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 18
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    Chemical Engineering & Technology - CET 12 (1989), S. 20-26 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: For design and simulation of chemical process furnaces in accordance with present-day standards, the temperature distributions in the firebox and in the reactors must be generated simultaneously. This calls for coupling of the simulations of the firebox and of the reactor. For the calculation of heat transfer in the firebox, a generalized furnace simulations program, based on the zone method, is applied. Monte Carlo simulation techniques are used to determine the view factors. The location of the burners is explicitly accounted for. Absorption and emission of radiation by the flue gas are calculated by considering band contributions for carbon dioxide and water. For the simulation of the steam reforming reactors, a one-dimensional heterogeneous model, which accounts for the presence of intraparticle partial pressure gradients, is used. The simulated temperature distribution in the furnace is in excellent agreement with industrial results, as is the simulated product distribution.
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  • 19
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    Chemical Engineering & Technology - CET 12 (1989), S. 333-339 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The most important investigations on liquid weeping and entrainment in plate columns with downcomers are reveiwed. The formulae for calculating column plate efficiency under conditions of liquid weeping and entrainment have been derived on the basis of mass balance equations. The presented model is a generalization of the models of AIChE and Colburn. Sample results are shown graphically. The effect of liquid entrainment on tray efficiency predicted by the model is in agreement with experimental data of FRI.
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  • 20
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The knowledge of the heat transfer coefficient on the inner side of a heated vessel wall is of the utmost importance for the design of agitated vessels. In the case of large Reynolds numbers, the heat transfer is mainly determined by these numbers whereas, with small Reynolds numbers, the heat transfer is better described by considering the Grashof number. Investigations of heat transfer in agitated narrow vessels have shown that the height/diameter ratio exerts virtually no influence on the heat transfer when multi-impeller stirrers are used. The heat transfer to stirred suspensions can be described by relationships valid for liquids if the characteristic data of the liquid are replaced by those of the suspension and when the solids volume concentration is also taken into account. This relationship allows the heat transfer coefficient to be calculated for given solids volume concentrations of up to 60%.
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  • 21
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In order to achieve optimal energy-saving, load-dependent operation of rectification columns, development and implementation of model-based control concepts are necessary. This paper reports on the design and step-by-step testing of a state observer for the estimation of two state variables which cannot be measured directly, namely the vapour rate and the location of mass transfer zone (temperature front) in the stripping section of a production column. The procedure is described, and the relevant simulation and operation results are presented and discussed. Initial experience, gained when the concept was put into practical operation, is reported.
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  • 22
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    Chemical Engineering & Technology - CET 12 (1989), S. 345-350 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Continuous crystallization of potassium carbonate was investigated in a mixed suspension mixed product removal (MSMPR) crystallizer with 7.0 1 working volume. Highly polydispersed product was obtained, with x50 varying between 320 and 670 μm. Crystal growth rates can be described by the model of Abegg, Stevens and Larson (ASL) (size dependent crystal growth rate). Values of G0 = 8.6 × 10-9 to 3.6 × 10-8 m/s and B0/ϕ = 2.7 × 108 to 4.2 × 109 1/m3s were obtained for mT = 45 to 92 kg/m3 and ε = 0.45 ± 0.05 W/kg. Nucleation kinetics at 27 °C can be described by the equation: B0/ϕ = kBϕsε0.73G02.5. Since G0 ∝ σ, convection and/or diffusion rather than surface integration are the crystal growth controlling mechanisms.
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  • 23
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    Chemical Engineering & Technology - CET 12 (1989), S. 356-357 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    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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    Chemical Engineering & Technology - CET 12 (1989), S. 54-63 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: When a chemical reactor is depressurized or pressure in a vessel, filled with saturated liquid, has to be decreased, generally both vapour and liquid flow out through the relief valve. Since chemical reactors are usually operated with toxic and explosive fluids, the discharged liquid which vaporizes on the ground around the vessel may reach dangerous concentrations, causing explosions or accidents with the poisonous gas. During a research project, some fundamentals were developed for the design of separation systems which separate liquid from vapour and store it in a receiver. The requirement for a separation efficiency of a least 80% is related to the condition that the separated liquid should flow back into the reactor still during the pressure relief phase. For safety reasons, both separation and re-storage are to be carried out without the supply of external energy. Theoretical and experimental investigations of pressure distribution within the piping to the relief valve and in an integrated separator show that re-storage of the separated liquid in the vessel can be achieved under certain flow conditions. Therefore, the separator must be integrated in the pipe at a certain height above the vessel, so that the hydrostatic pressure of the separated liquid, corresponding to the difference in height, is sufficient to lead it back through another pipe against the internal pressure of the vessel. First, several separators were tested with air-water mixtures. A swirl separator and a reversing separator have been developed to such an extent that they appear suitable for the set task. Experimental results with air-water mixtures and refrigerant R12 upon pressure relief show separation efficiencies of between 90 and 100% at low pressure drops within the whole operating range. As an alternative to separation outside the vessel, a rotary separator was also developed which is fixed to the outlet opening in the vessel. A centrifugal field is produced by the separator rotor and the heavier liquid is largely separated from the vapour so that only drops in the range 〈 100 μm flow together with the vapour towards the central standpipe. The outflowing vapour leaves the separator via 4 tangentially arranged nozzles, under critical conditions. The vapour flow momentum drives the separator rotor. The arrangement was developed and tested during various series of experiments, under conditions or pressure relief with refrigerant R12. So far, separation efficiencies between 60 and 95% have been achieved at stirring speeds of up to 2500 min-1.
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  • 25
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    Chemical Engineering & Technology - CET 12 (1989), S. 89-96 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Depressurization of a pressure vessel, containing a liquid or a gas is limited by the maximum possible mass flux. This flux occurs at a certain drop in pressure. The ratio of ambient pressure to that inside the vessel must be less than a certain critical value. The critical pressure ratio depends on the thermodynamic state of the fluid inside the vessel and on the geometry of the outlet cross-section. The outlet can be a pipeline, a safety valve or a rupture disk. The results of known theoretical and experimental work are presented. In previous experiments, saturated liquids, two-phase flows or pure vapours were examined. In order to predict the critical pressure ratio, certain assumptions are necessary. These are derived for three well-defined cross-sections of the vessel outlet.
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  • 26
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    Chemical Engineering & Technology - CET 12 (1989), S. 103-109 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: During the past decade, the sintering of model supported metal catalysts, i.e. catalysts consisting of metal deposited on very thin and flat oxide films, has been intensively investigated by transmission electron microscopy. In the current paper, a mathematical model, based on an atomic migration mechanism, for the sintering of these catalysts is presented. The predictions of the model, based on Monte Carlo simulations, are in very good agreement with the experimental observations, i.e. phenomena such as ‘apparent’ particle migration, splitting and neck formation between particles are predicated by the model.
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  • 27
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    Chemical Engineering & Technology - CET 12 (1989), S. 109-112 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Anaerobic fermentation of molasses distillery slops to biogas was carried out with the aid of an adapted and selected anaerobic mixed culture. Two different types of fermenters were used, namely an agitated pretreatment fermenter and a column fermenter with glass rings as carriers for micro-organisms. The production of biogas in both fermenters amounted to between 0.6 and 0.8 dm3/g COD. The aerobic pretreatment of distillery slops by T. fermentans, yeast during a 4 to 6 h period allows a high reduction of COD in the subsequent anaerobic phase of the process. After treatment of the distillery slops by T. fermentans, it was possible to convert between 85 and 93% of the organic matter to methane. Conversion was about 93% with loading rate of 25g COD/litre day.
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  • 28
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    Chemical Engineering & Technology - CET 12 (1989), S. 155-161 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The conversion of methanol over zeolite H-T was investigated in a fixed bed reactor. H-T was prepared from Na-T by ion exchange with HCl and NH4Cl solutions. The HCl solution caused appreciable dealumination. High yields of ethene were obtained with NH4Cl exchangeed zeolites Na-T with 45% decationization, high proprne yields with low HCl or NH4Cl Exchanged catalysts. Low methanol partial pressures and short residence times favoured the formation of lower olefins. Lowest coking rates were observed at a reaction temperature of 693 K. The catalytic activity decrased slowly with the number of reaction/regeneration cycles. The distribution of procucts 〉 C2 could be described by the most probable distribution of Schulz and Flory.
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  • 29
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    Chemical Engineering & Technology - CET 12 (1989), S. 170-175 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper presents a method mathematical modelling of cocurrent multitubular fixed-bed reactors. The method is adapted to the most widespread type of industrial reactor design, i.e. the system fitted with disk-and-doughnut baffles. The proposed model makes it possible to estimate the influence of non-uniformity of the heat carrier flow on the reactor characteristics, taking into account the coolant streams by-passing via the tube-to-baffle clearances. Based on the model, the effect of the operating parameters as well as of some more important geometrical parameters of the reactor on an exemplary highly exothermic process of partial benzene oxidation to maleic anhydride is discussed.
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  • 30
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    Chemical Engineering & Technology - CET 12 (1989), S. 188-195 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Collection efficiency and pressure loss of a venturi scrubber can usually be determined from the calculation models of Barth and Calvert. However, this only leads to reasonable results if the droplets are uniformly distributed throughout each cross-section of the washing zone. In this work, a two-zone models is developed which allows the calculation of the venturi scrubber at operating conditions with a non-uniform droplet distribution. The scrubber geometry is also taken into account. A venturi scrubber was developed on the basis of this new model. Its energy consumption is significantly lower than the well-Known optimum characteristic of Wicke and Holzer. For ideal operating conditions, a new optimum characteristic is given which should be the aim of future optimizations.
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  • 31
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Steady-state concentrations of the transferred reactant in the bulk phase and the non-flowing diffusion boundary layer of an isothermal, isobaric two-phase reactor with an irreversible first-order reaction and constant composition of one phase.
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  • 32
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    Chemical Engineering & Technology - CET 12 (1989), S. 200-204 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A model of floc destruction resulting form mass forces in a centrifugal field is postulated and its validity examined. This model is to be regarded as a supplement to the existing shear-loading disagglomeration models. In order to verify this additional floc disintegration mechanism, appropriate investigations were carried out with flocculated suspensions of silica and Hamburg dock sludge. As a result, in addition to floc disintegration by shear forces within a turbulent flow and in the centrifuge inlet, the existence of another mechanism was demonstrated. This consists in the floc destruction in a centrifugal field where particles in excess of a certain size, or specifically heavier components, are preferentially torn out of the floc. This floc disintegration by mass forces can lead to a classification effect in centrifuges which also subject the flocs to instant high centrifugal forces.
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  • 33
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    Chemical Engineering & Technology - CET 12 (1989), S. 205-212 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A circular loop reactor was built for application to a heterogeneous liquid-liquid reaction. In order to investigate the dispersion behaviour of droplets in the reactor, basic experiments were performed using a number of liquid-liquid dispersions. Droplets discharged form the impeller region were found to grow due to coalescence in the circulation region. Mean droplet diameter decreased exponentially with elapsing time. An expression correlating the steady-state mean droplet diameter with the operating conditions was derived. Moreover, the transition time required for the droplet diameter to reach the equilibrium value was determined and correlated with the operating conditions.
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  • 34
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    Chemical Engineering & Technology - CET 12 (1989), S. 213-217 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Important aspects of K1a measurement in agitated aerated vessels are briefly characterized from the standpoint of reliability of the measured data. An analysis of the shortcomings of dynamic methods for measuring the K1a is given. A new modification of the dynamic method is proposed, which excludes these inadequacies through a special experimental arrangement. This was verified by comparing the data with those obtained by an independent steady-state method. The new method can serve as a standard of reference, suitable for testing newly developed methods for K1a measurement. The initial response method was tested in this way in non-coalescent liquids, and shown to lead to errors of the order of hundreds of percent. K1a values obtained with the initial response method were found to depend strongly on the probe's location in the vessel.
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  • 35
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Secondary nucleation in industrial crystallizers depends on both supersaturation and mechanical stress by stirring. Most models which consider mechanical stress assume that nucleation is proprotional to the energy transferred to the crystals during collisions. This is not based on any physical relationship and, in addition, the models do not satisfactorily reproduce the experimental results. Own model, based on the theory of Hertz/Huber, which accounts for the stress of the crystals caused by impact, gave better results. This well-known and proven theory allows the calculation of the volume abraded during collisions between crystals and stirrer or walls. Introducing a nucleate efficienncy, the effect of mechanical stress on the rate of secondary nucleation, due to stirring intensity and crystallizer size, can be determined.
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  • 36
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    Chemical Engineering & Technology - CET 12 (1989), S. 147-154 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The sintering effect of highly dispersed metals is the reason for the following phenomena: thermal deactivation, particle size effect, separable or non-separable kinetics and the isokinetic relationship ( = compensation effect). A comparison of these phenomena reveals a contradiction which can be reconciled by a new particle size effect. This effect is characterized in the following way: The dependence of specific activity on particle size is always connected with a variation of the activation energy, caused by the particle size distribution. Therefore, this effect is referred to as the partical size and distribution effect, P.S.D.E. This new concept describes all the observed phenomena of the conventional partical size effect. Moreover, it is consistent with similar effects such as non-separable kinetics and the isokinetic relationship. In consequence, the method of isothermal measurement of specific activity is inadequate.
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  • 37
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    Chemical Engineering & Technology - CET 12 (1989), S. 255-261 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Carman-Kozeny equation is applicable in the viscous flow regime but, as the powder becomes finer, this equation fails. The controlling factor is the ratio of the hydraulic diameter to the mean free path of gas molecules (rH/λ) and, as this approaches unity, “slip flow” occurs. This effect increases with (a) increasing fineness, i.e. rH reduced, (b) decreasing porosity, i.e. rH reduced, and (c) decreasing pressure, i.e. λ increased. In order to account for the enhanced flow arising as a result of this failure, a second term is introduced into the equation and this includes an unknown “constant” (δK0/K), the coefficient of slip. It was considered probable that this so-called constant was a function of (rH/λ), and an attempt was made to investigate this relationship.
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  • 38
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    Chemical Engineering & Technology - CET 12 (1989), S. 269-273 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 39
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    Chemical Engineering & Technology - CET 12 (1989), S. 262-269 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Studies of flow characteristics and residence time distribution, (RTD), have been undertaken in a range of geometrically similar, laboratory nozzle-type reactors. High-speed cine-photography was employed to record the complex phenomena of liquid mixing in the reactor and also to record on film the colour of an injected tracer solution leaving in the effluent. A novel atomic absorption spectrophotometric (AAS) technique was applied to transform the results of the latter film into response curves. This technique provide detailed quantitative data on the residence time distributions (RTD) for different feed rates. A multiparameter model, comprising a network of CSTR's and plug flows, was developed to simulate the experimental response data. Good agreement was obtained between model predictions and experimental results. The experimental technique and theoretical approach are recommended for analyzing the flow patterns and mixing mechanisms in such reactors.
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  • 40
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A superposition of simple physical equations allows a satisfactory, comprehensive fluid dynamic description of jet-loop reactors in multiphase operation up to a dispersed phase hold-up of 15%. In the case of higher concentrations, there are further interactions which are not yet included in the model description. Apart from the drag coefficient of the single-phase jet loop, information on the particle swarm behaviour, i.e. on the slip velocity of the dispersed phase is required. Explicit formulation of the influence of the relevant geometrical parameters permits a reliable scale-up without additional adaptation parameters.
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  • 41
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    Chemical Engineering & Technology - CET 12 (1989), S. 280-288 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A cubic equation of state is modified in such a way that prediction of PVT data from 40 model compounds, typical of coal oil, becomes possible with an absolute mean deviation of less than 2% for saturated liquid volumes and vapour pressures 〉 1 bar. Additional correlations for binary interaction parameters are obtained by an optimization procedure using vapour-liquid euilibrium (VLE) data from known heavy hydrocarbon liquid/light gas systems. When the modified equation is applied to coal-derived liquids, only specific gravity and boiling analysis data of the coal liquids are required, primarily in order to determine the equation-of-state parameters. The proposed equation is shown to allow a good prediction of VLE data for systems consisting of wide-boiling-range coal oils and light gases. Experimental values were obtained at elevated temperatures and pressures with a circulation flow apparatus.
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  • 42
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Heat transfer and fluid mechanical data were computed for laminar channel flows containing strong longitudinal vortex pairs. The strong vortices are generated by thin delta wings and delta winglet pairs of low aspect ratios and large angles of attack. These wings are attached to the channel walls. The data show that longitudinal vortices cause high local peaks in heat transfer and marked increases in the overall channel heat transfer. These increases occur over a wide region of channel wall, compared to the vortex generating wing area. The results are of special interest for compact heat exchangers. The heat transfer enhancement allows a considerable reduction in the heat transfer area which, in turn, reduces the manufacturing and operating costs.
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  • 43
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Grade efficiencies must be measured in order to characterize particle collection in cyclones. For real, irregularly shaped partcles, the grade efficiencies depend on the shape and orientation of the particles and the flow around them. Therefore, the collection characteristics of cyclones should be defined in relation to spherical particles. Deviations occurring on the use of real, irregularly shaped dusts can then be attributed to a material influence. A fast and accurate measuring technique to determine the collection characteristic for spherical particles is described, followed by the presentation of results of extensive investigations on small model cyclones. A similarity relationship is presented. The validity of this relationship was confirmed by investigations with similar, larger cyclones.
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  • 44
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    Chemical Engineering & Technology - CET 12 (1989), S. 33-37 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The absorption of nitric oxide (NO) in phosphoric acid esters and polyethylene glycol ethers which contain cupric halides has been investigated. Due to high solubility of cupric halides and high equilibrium constants of formed nitrosyl complexes, the effective solubility of nitric oxide can be enhanced to about 100-fold its solubility in the salt-free organic liquid which itself amounts to only about 5-fold the NO-solubility in water. Calculations taking into account flue gas conditions indicate that the required gas-liquid ratio in industrial absorption processes will lie in the normal range of flue gas scrubbing processes, namely in the region of 400:1 to 1000:1 in volume. Thus, such a reversible absorption process could a viable alternative to SCR-processes in flue gas denitrification.
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  • 45
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    Chemical Engineering & Technology - CET 12 (1989), S. 96-102 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of alkali treatment, nitrogen supplement and hydraulic retention time on methane production rate from semi-continuous anaerobic digestion of 5% wheat straw-water mixtures were investigated. The experiments were carried out in laboratory scale fermenters, fed with 1 1 of basic, alkali treated and nitrogen supplemented 5% wheat straw-water mixtures, respectively, and maintained at 55 °C. Digestion experiments were performed for hydraulic retention times of 8, 10 and 15 days. The amount and composition of produced gas were measured until steady state was attained in each run. The steady-state methane production rates were found to increase with hydraulic retention time and with the type of slurry in the following order; basic, nitrogen supplemented and alkali treated slurry. Data obtained from the experiments were employed to determine the kinetics of methane production from anaerobic digestion of wheat straw, for the assessment of pretreatment effects on process kinetics. The predicted methane production rates were found to be in a reasonably good agreement with the measurements.
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  • 46
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    Chemical Engineering & Technology - CET 12 (1989), S. 71-87 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the course of polymerization in homogeneous systems, the viscosity of the reaction mass increases by several orders of magnitude. The viscosity increase is affected by reaction conditions, concentration and properties of the formed polymer. Empirical correlations for homogeneous and heterogeneous polymerizations are given. Viscosity significantly affects the polymerization kinetics as well as heat, mass and momentum balances of the polymerization reactor. The influence of viscosity and its increase on conductive heat transfer, stirrer power input and cooling capacity, molecular diffusion and mass transfer coefficients, mixing time and residence time distribution in homogeneous and heterogeneous polymerizations in stirred tank and tubular reactors is reviewed.
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  • 47
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    Chemical Engineering & Technology - CET 12 (1989), S. 113-130 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Starting from the review of current industrial designs, the present paper analyzes thermal interaction between reactants and coolant in multitubular fixed-bed reactors. The interaction can be described quantitatively in terms of parameters characterizing transport processes both on the tube side and in the intertubular space. The study provides a detailed discussion of existing methods and correlations used for the evaluation of these parameters. The methods presented here can be considered as a basis for the development of a more comprehensive approach to the modeling and design of multitubular catalytic reactors.
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  • 48
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The prediction of leak areas in pressure vessels is an important objective in the safety analysis of chemical plants. Using suitable design rules, a leak-before-break behaviour can be achieved. This contribution outlines a procedure for the leak-before-break design of nozzle attachments and the determination of the size of the corresponding opening area. In addition, K1-factors and leak areas for a number of nozzle geometries have been calculated and plotted.
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  • 49
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    Chemical Engineering & Technology - CET 12 (1989), S. 218-225 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Most chemical engineers presently accept that the mass transfer rate in desorption from the solid to the gas phase or from the liquid to the gas phase is accelerated with increasing temperature in the liquid or the solid phase, or increasing partial pressure of inert gas in the gas phase, and/or decreasing total system pressure in the gas phase. Nevertheless, many reports about such mass transfer are still based on the former concept, which completely contradicts the actual phenomena mentioned above. Here, we discuss the contradiction and suggest a way of resolving it in terms of diffusion theory.
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  • 50
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    Chemical Engineering & Technology - CET 12 (1989), S. 226-233 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The explosion behaviour of CH4/air mixtures inside a closed 0.065 m3 spherical and a 1 m3 cylindrical vessel was investigated to determine the effect of turbulence on the structure and propagation rate of transient turbulent flames for different initial turbulence levels generated by 4 ventilators installed inside the equipment. Laser-Doppler and hot wire anemometry were used to measure the turbulent motion. It was found that fairly uniform turbulence could be achieved in the central zones of the vessels and that the RMS-values of flow velocity were proportional to the ventilator speed. The evaluation of burning velocity from the pressure/time records showed that, starting from an initial burning velocity which depends on the initial turbulence level, the flame accelerates as a result of pressure, temperature and turbulence effects. Maximum burning velocity coincides with the inflexion point of the pressure/time curve, and is followed by a rapid deceleration of the flame front. A linear relationship between burning velocity and measured RMS-velocity is recognized in the observed range of RMS-values.
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  • 51
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Distillation has been, up to now, the standard method for separating fluid mixtures in the process industry and the consensus is that it will remain so for years to come. The only disadvantage of distillation is its high energy requirement. In the following, it will be demonstrated on the example of an ideal ternary mixture, how the energy requirement of distillation process can be reduced. Very effective are some modifications of single columns, optimization of column sequences and direct or indirect column coupling. It will be shown that, just by column coupling, the energy requirement can be reduced to a third.
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  • 52
    ISSN: 0930-7516
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The influence of turbulence on local heat and mass transfer is systematically analyzed. Essential prerequisite is the availability of measurement methods, based on convective mass transfer, which allow the visualization of heat and mass transfer distributions. The results show that, even at low turbulence intensities, the flow and transport phenomena are decisively influenced by the specific design of turbulence grids and the orientation of the grid wires with respect to the stagnation line. Thereby, two different flow mechanisms occur which may interact. The anisotropy of grid turbulence leads to the “wire-gap effect” depending on the actual position of the grid wires in relation to the stagnation line. The other mechanism is based on the wavy wake velocity distribution behind screens and grid which, in conjunction with the centrifugal instability of stagnation flows, may lead to longitudinal vortices. The results indicate why turbulence has not been sufficiently considered in the available (semi-) empirical correlations. Information needed for an accurate prediction of heat and mass transfer in turbulence flows is discussed.
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  • 53
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An independent preliminary mechanistic prediction method for leakage rates through small slit-shaped through-wall cracks, based on coupled pressure drop and (critical) mass flux calculation is presented. The predictions are verified against initially subcooled liquid refrigerants and water data collected during experiments in real and model cracks in a wide range of parameters. The achieved accuracy of prediction is already comparable to that of the experimental results. Further model modifications are put forward.
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  • 54
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    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: To improve the rate of convergence of random search optimization procedures, the incorporation of a gradient-oriented one-dimensional search is investigated. With this modification to the random search procedure based on uniform sampling and region contraction [1], convergence to within 0.01% of the global optimum was obtained substantially faster for typical chemical engineering problems. It was also found that the reliability of obtaining the global optimum was improved.
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  • 55
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    Chemical Engineering & Technology - CET 12 (1989), S. 318-323 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A special stress measuring device for determining the normal and shear stresses acting on silo walls was developed and tested. The load cell can be used for measuring simultaneously the normal stress as well as the intensity and direction of the shear stress.
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  • 56
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The chlorination of an alumina with BET surface area of 100 m2/g has been studied in situ by transmission IR measurements at about 670 K. The chlorinating gases consisting of Cl2 and CO were employed individually and in equimolar proportion. The IR results do not reveal the presence of a phosgene surface species which could support the only mechanism proposed so far to explain the chlorination. A detailed alternative reaction mechanism is suggested for the high temperature chlorination reaction, taking into account the IR results, together with the known electron donor-acceptor properties of the activated alumina and the reaction gases: Cl2 molecules accept electrons from oxide ions with a lower coordination number on the alumina surface, leading to the formation of Cl-and Oad. While Cl- yields AlCl3, Oad reacts further with CO producing CO2.
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  • 57
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The vapour phase hydrogenation of 1,3-cyclo-octadiene (COD) over Pd on alumina has been studied in the gas phase, using a recycle reactor. The dependences of COD hydrogenation rates and those of the consecutive cyclo-octene (COE) hydrogenation on the reaction conditions are well described by a model which takes into account mass transfer in the porous layer of palladium. The kinetics of the COE hydrogenation is of a Langmuir-Hinshelwood type. The hydrogenation of COD is of first order with respect to hydrogen. The reaction order with respect to COD is -0.15. If the catalyst surface is completely covered by COD, the hydrogenation of COE is totally suppressed. This indicates a much stronger adsorption of COD than of COE. Hydrogenation of COE can only occur in the innermost part of the pores when the transport of COD by diffusion is insufficient to supply the entire active surface of the catalyst. This happens if the ratio PH2/PCOD exceeds 2/ϕ2 with ϕ being the Thiele's modulus. This relationship permits a simple evaluation of the effective diffusion coefficient in the porous Pd-layer.
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  • 58
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    Chemical Engineering & Technology - CET 12 (1989), S. 63-70 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It is shown in this report that, under certain conditions, cleaning of exhaust air by absorption presents an interesting alternative to the existing methods. In particular, this process can be used with advantage for small quantities of exhaust air, high and strongly fluctuating solvent concentrations and solvent mixtures such as those occurring in batch operation. A washing agent was employed which had not been previously used for this purpose. Its properties, which were investigated in the laboratory, were confirmed during a 15-months' trial period in a semi-industrial plant. The process and plant were optimized for practical use. Through its option of solvent recovery from exhaust air, this physical absorption process contributes to environmental control.
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  • 59
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Combustion rate of flat graphite plates in oxidizing flows with velocities of up to 80 m/s and stagnation temperatures between 1600 and 2500 K were investigated. The flow field and its local properties were recorded in addition to surface temperature of the solid sample and change in surface structure. The experiments, in which the surface temperature of graphite was adjusted and carefully controlled by radiation shields, indicated that, under these experimental conditions, between 15 and 20 wt-% of carbon was lost as particles of up to 100 μm which burnt rapidly in the boundary layer region. Subtraction of erosion rates from the recorded global combustion rates yield the heterogeneous chemical reaction rates, which are approximated by an Arrhenius type function for the mathematical modelling. Since steep temperature and concentration gradients occur in the boundary layer, the local values of the multicomponent transport coefficients were evaluated in order to design a more realistic computational procedure which, in addition, also includes radiative heat transfer. Computational checks revealed that, in the past, the assumption of mean constant values for the transport coefficients has led to errors of up to 100% in the evaluation of the chemical reaction and global combustion rates.
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  • 60
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    Chemical Engineering & Technology - CET 12 (1989), S. 358-364 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The energy consumption of ammonia plants based on steam reforming of naphtha or natural gas can be reduced by shifting the reforming load from the primary to the secondary reformer. It is shown that lowering of the primary reformer operating temperature 20 °C results in 2% increase of unconverted methane content in the outlet stream. The increased methane content can be processed in the secondary reformer if the process air inlet temperature is increased to 400 °C. The lower operating temperature reduces the energy consumption of the primary reformer by about 6% (and the overall consumption by about 2%) and also prolongs the service life of reformer tubes.
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    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989) 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 62
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 1-11 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of micromixing limits on a process of crystallization in an MSMPR crystallizer is studied with respect to power law growth and nucleation kinetics. Three limiting cases corresponding to maximum mixedness and complete segregation in an MSMPR crystallizer and plug flow configuration were analyzed for processes in which supersaturation is generated by conventional techniques. The sensitivity of these three limiting cases to the supersaturation generation term in each mode of operation was investigated using several numerical examples. The study demonstrates the effects of mixing on the overall crystallizer performance and, in particular, the enormous micromixing influence at high supersaturation generation rates. The difference in the product CSD arise from the variations of supersaturation profiles experienced by the elementary volumes throughout their sojourn. Characterization of mixing in a real crystallizer at some intermediate levels is emphasized with the aid of relevant industrial examples.
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  • 63
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 15-19 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Effective interfacial area a and volumetric liquid-side mass transfer coefficient kLa of an RTL contactor were obtained at different stirring speeds by absorption of oxygen from air into 0.8 kmol/m3 sodium sulphite solution, in the presence of Co++ ions. The values of a and kLa ranged from 80 to 150 m2/m3 and 0.0003 to 0.00053 s-1, respectively, when stirrer speed was increased from 8 to 40 rpm. When kL alone was evaluated, it was found to be practically constant, irrespective of stirring speed.
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  • 64
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This contribution reports on the theory underlying a uniform representation of heat transfer to submerged surfaces in fixed bed reactors and of gas convective part of heat transfer in fluidized beds with coarse-grained bulk solids and/or at elevated pressure. Based on an analysis of the pressure drop behaviour of fixed bed percolation at different gas pressures and with different bulk solids, a new dimensionless pressure drop parameter was developed. Fixed bed heat transfer data are very well correlated by this new dimensionless number. As soon as fluid throughput is in excess of minimum fluidization velocity, the pressure drop parameter transforms into the well-known Archimedes number. These two dimensionless numbers are connected by the condition of equilibrium for pressure drop and mass of practices in a fluidized bed. This equilibrium is fulfilled as soon as fluidization commences. Up to now, the Archimedes number has been generally accepted as the significant parameter, determining the gas convective part of heat transfer in fluidized beds; however, without any physical interpretation of this parameter. Introduction of the pressure drop number, which is consistent with the Archimedes number, reduces the heat transfer behaviour to pressure drop characteristics. The usefulness of this concept is proven by the comparison of experimental results and prediction.
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  • 65
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-04-28
    Description: The first sentence of reference 15 in the report "Single-chain antigen-binding proteins" by Robert E. Bird et al. (21 Oct., p. 423) should have read, 'The majority of experiments have produced Ka's within a factor of 2 of these values; therefore, log K(a)'s for the 4-4-20 I, Fab, and 4-4-20/20' single-chain protein are 10.2, 9.9, and 9.0+/-0.3, respectively.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉New York, N.Y. -- Science. 1989 Apr 28;244(4903):409.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2717931" target="_blank"〉PubMed〈/a〉
    Keywords: Animal Testing Alternatives ; *Animal Welfare ; Animals ; *Animals, Laboratory ; Ethics ; Societies ; United States
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  • 66
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-01-20
    Description: Human and murine mononuclear phagocytes express a high-affinity receptor for immunoglobulin G that plays a central role in macrophage antibody-dependent cellular cytotoxicity and clearance of immune complexes. The receptor (FcRI) may also be involved in CD4-independent infection of human macrophages by human immunodeficiency virus. This report describes the isolation of cDNA clones encoding the human FcRI by a ligand-mediated selection technique. Expression of the cDNAs in COS cells gave rise to immunoglobulin G binding of the expected affinity and subtype specificity. RNA blot analysis revealed expression of a 1.7-kilobase transcript in macrophages and in cells of the promonocytic cell line U937 induced with interferon-gamma. The extracellular region of FcRI consists of three immunoglobulin-like domains, two of which share homology with low-affinity receptor domains.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Allen, J M -- Seed, B -- New York, N.Y. -- Science. 1989 Jan 20;243(4889):378-81.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology, Massachusetts General Hospital, Boston 02114.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2911749" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Blotting, Northern ; Cercopithecus aethiops ; Cloning, Molecular ; DNA/genetics ; Gene Expression Regulation ; Humans ; Molecular Sequence Data ; Molecular Weight ; Polymorphism, Genetic ; Receptors, Fc/*genetics ; Transfection
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  • 67
    Publication Date: 1989-04-14
    Description: Previous studies have demonstrated that allelic deletions of the short arm of chromosome 17 occur in over 75% of colorectal carcinomas. Twenty chromosome 17p markers were used to localize the common region of deletion in these tumors to a region contained within bands 17p12 to 17p13.3. This region contains the gene for the transformation-associated protein p53. Southern and Northern blot hybridization experiments provided no evidence for gross alterations of the p53 gene or surrounding sequences. As a more rigorous test of the possibility that p53 was a target of the deletions, the p53 coding regions from two tumors were analyzed; these two tumors, like most colorectal carcinomas, had allelic deletions of chromosome 17p and expressed considerable amounts of p53 messenger RNA from the remaining allele. The remaining p53 allele was mutated in both tumors, with an alanine substituted for valine at codon 143 of one tumor and a histidine substituted for arginine at codon 175 of the second tumor. Both mutations occurred in a highly conserved region of the p53 gene that was previously found to be mutated in murine p53 oncogenes. The data suggest that p53 gene mutations may be involved in colorectal neoplasia, perhaps through inactivation of a tumor suppressor function of the wild-type p53 gene.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Baker, S J -- Fearon, E R -- Nigro, J M -- Hamilton, S R -- Preisinger, A C -- Jessup, J M -- vanTuinen, P -- Ledbetter, D H -- Barker, D F -- Nakamura, Y -- White, R -- Vogelstein, B -- GM07184/GM/NIGMS NIH HHS/ -- GM07309/GM/NIGMS NIH HHS/ -- HD20619/HD/NICHD NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1989 Apr 14;244(4901):217-21.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Oncology Center, Johns Hopkins University School of Medicine, Baltimore, MD 21231.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2649981" target="_blank"〉PubMed〈/a〉
    Keywords: Alleles ; Animals ; *Chromosome Deletion ; *Chromosomes, Human, Pair 17/ultrastructure ; Colorectal Neoplasms/*genetics ; Humans ; Mice ; Mice, Nude ; *Mutation ; Neoplasm Proteins/*genetics ; Nucleic Acid Hybridization ; Oncogenes ; Phosphoproteins/*genetics ; Suppression, Genetic ; Tumor Suppressor Protein p53
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  • 68
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-06-30
    Description: Hibernating arctic ground squirrels, Spermophilus parryii, were able to adopt and spontaneously arouse from core body temperatures as low as -2.9 degrees C without freezing. Abdominal body temperatures of ground squirrels hibernating in outdoor burrows were recorded with temperature-sensitive radiotransmitter implants. Body temperatures and soil temperatures at hibernaculum depth reached average minima during February of -1.9 degrees and -6 degrees C, respectively. Laboratory-housed ground squirrels hibernating in ambient temperatures of -4.3 degrees C maintained above 0 degree C thoracic temperatures but decreased colonic temperatures to as low as -1.3 degrees C. Plasma sampled from animals with below 0 degree C body temperatures had normal solute concentrations and showed no evidence of containing antifreeze molecules.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Barnes, B M -- HD 23383/HD/NICHD NIH HHS/ -- New York, N.Y. -- Science. 1989 Jun 30;244(4912):1593-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks 99775-0180.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2740905" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antifreeze Proteins ; Arctic Regions ; Arousal ; *Body Temperature ; Body Temperature Regulation ; Female ; *Freezing ; Glycoproteins/analysis ; *Hibernation ; Male ; Sciuridae/*physiology
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  • 69
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-01-06
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Barnes, D M -- New York, N.Y. -- Science. 1989 Jan 6;243(4887):29-30.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2911718" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Humans ; *Legislation, Drug ; *Neurotoxins/toxicity ; United States ; United States Food and Drug Administration
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  • 70
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-02-24
    Description: Cruciform DNA, a non-double helix form of DNA, can be generated as an intermediate in genetic recombination as well as from palindromic sequences under the effect of supercoiling. Eukaryotic cells are equipped with a DNA-binding protein that selectively recognizes cruciform DNA. Biochemical and immunological data showed that this protein is HMG1, an evolutionarily conserved, essential, and abundant component of the nucleus. The interaction with a ubiquitous protein points to a critical role for cruciform DNA conformations.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bianchi, M E -- Beltrame, M -- Paonessa, G -- New York, N.Y. -- Science. 1989 Feb 24;243(4894 Pt 1):1056-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉European Molecular Biology Laboratory, Heidleberg, Federal Republic of Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2922595" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Cloning, Molecular ; DNA/genetics/*metabolism ; Electrophoresis, Polyacrylamide Gel ; High Mobility Group Proteins/genetics/isolation & purification/*metabolism ; Immunoassay ; Immunoblotting ; Liver/analysis ; Molecular Sequence Data ; Molecular Weight ; *Nucleic Acid Conformation ; Peptide Fragments/genetics/isolation & purification ; Protein Biosynthesis ; Rats ; Transcription, Genetic
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  • 71
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-05-05
    Description: Tumor promoters may bring about events that lead to neoplastic transformation by inducing specific promotion-relevant effector genes. Functional activation of the transacting transcription factor AP-1 by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) may play an essential role in this process. Clonal genetic variants of mouse epidermal JB6 cells that are genetically susceptible (P+) or resistant (P-) to promotion of transformation by TPA were transfected with 3XTRE-CAT, a construct that has AP-1 cis-enhancer sequences attached to a reporter gene encoding chloramphenicol acetyltransferase (CAT). Transfected JB6 P+, but not P- variants, showed TPA-inducible CAT synthesis. Epidermal growth factor, another transformation promoter in JB6 cells, also caused P+ specific induction of CAT gene expression. These results demonstrate an association between induced AP-1 function and sensitivity to promotion of neoplastic transformation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bernstein, L R -- Colburn, N H -- New York, N.Y. -- Science. 1989 May 5;244(4904):566-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Johns Hopkins University, Department of Biology, Baltimore, MD 21218.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2541502" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cell Line ; *Cell Transformation, Neoplastic ; Chloramphenicol O-Acetyltransferase/genetics ; Cloning, Molecular ; DNA-Binding Proteins/genetics/*physiology ; Epidermal Growth Factor/pharmacology ; Epidermis ; Gene Expression Regulation ; Genetic Variation ; Kinetics ; Mice ; Nucleic Acid Hybridization ; Plasmids ; Promoter Regions, Genetic ; Proto-Oncogene Proteins ; Proto-Oncogene Proteins c-jun ; Simplexvirus/genetics ; Tetradecanoylphorbol Acetate/*pharmacology ; Transcription Factors/genetics/*physiology ; Transfection
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  • 72
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-08-04
    Description: This lecture illustrates the early stages in the planning and discovery of propranolol, an adrenaline beta-adrenergic receptor antagonist, and cimetidine, a histamine H2-receptor antagonist--the first examples of clinically useful drugs from each of these classes. The significance of selective agonists, partial agonists, and syntopic antagonists and the importance of the bioassay and the use of molar models in the drug discovery process are discussed. For the future, an outline of potential developments in hormone-receptor concepts is offered leading to the conclusion that progress may depend on improvements in bioassays and related molar modeling.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Black, J -- New York, N.Y. -- Science. 1989 Aug 4;245(4917):486-93.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Analytical Pharmacology, Rayne Institute, King's College Hospital School of Medicine and Dentistry, London, United Kingdom.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2569237" target="_blank"〉PubMed〈/a〉
    Keywords: *Adrenergic beta-Antagonists/therapeutic use ; Angina Pectoris/drug therapy/physiopathology ; Animals ; Biological Assay ; Duodenal Ulcer/drug therapy ; Epinephrine/analogs & derivatives ; Histamine/analogs & derivatives ; *Histamine H2 Antagonists/therapeutic use ; Humans ; Stomach Ulcer/drug therapy
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  • 73
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-11-24
    Description: Although most animals reproduce sexually, a number of all-female groups exist. Triploid hybrid salamanders appear to maintain themselves by using a male's sperm to activate their eggs, after which the sperm nucleus is eliminated (gynogenesis). The incidence of sperm nuclear incorporation in eggs of these salamanders depends on temperature. Triploid offspring derived gynogenetically are more frequent at lower temperature, whereas tetraploid offspring derived sexually are far more frequent at higher temperatures. Temperature-dependent variability in sperm nuclear incorporation helps explain the variability in reproductive modes reported for hybrid salamanders.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bogart, J P -- Elinson, R P -- Licht, L E -- New York, N.Y. -- Science. 1989 Nov 24;246(4933):1032-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Zoology, College of Biological Science, University of Guelph, Ontario, Canada.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2587986" target="_blank"〉PubMed〈/a〉
    Keywords: Ambystoma/genetics/*physiology ; Animals ; Crosses, Genetic ; Female ; Karyotyping ; Larva ; Male ; *Polyploidy ; Sperm-Ovum Interactions ; Spermatozoa/*physiology ; Temperature
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  • 74
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-09-15
    Description: Locomotion and reaching have traditionally been regarded as separate motor activities. In fact, they may be closely connected both from an evolutionary and a neurophysiological viewpoint. Reaching seems to have evolved from the neural systems responsible for the active and precise positioning of the limb during locomotion; moreover, it seems to be organized in the spinal cord. The motor cortex and its corticospinal outflow are preferentially engaged when precise positioning of the limb is needed during locomotion and are also involved during reaching and active positioning of the hand near objects of interest. All of these motor activities require visuomotor coordination, and it is this coordination that could be achieved by the motor cortex and interconnected parietal and cerebellar areas.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Georgopoulos, A P -- Grillner, S -- NS17413/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1989 Sep 15;245(4923):1209-10.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Philip Bard Laboratories for Neurophysiology, Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, MD 21205.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2675307" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Forelimb/*physiology ; Humans ; *Locomotion ; *Psychomotor Performance ; Vertebrates/*physiology
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  • 75
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-03-17
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Goldberger, A L -- New York, N.Y. -- Science. 1989 Mar 17;243(4897):1419.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2928773" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Heart/*physiology ; Heart Conduction System/*physiology ; *Heart Rate ; Humans
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  • 76
    Publication Date: 1989-06-23
    Description: Although the T cell receptor (TCR) alpha beta heterodimer and its encoding genes have been characterized, a cell-free form of this receptor, which is needed for the study of functional or ligand-binding properties of the receptor, has not previously been isolated. When the cell-free supernatant products of activated cloned T helper (TH) cells were found to mediate helper activity with antigen specificity identical to that of intact T cells, experiments were carried out to determine whether this functional activity was mediated by a cell-free form of TCR-related material. A disulfide-linked dimer indistinguishable from the T cell surface alpha beta heterodimer was precipitated from cell-free supernatants of cloned TH cells with F23.1, a monoclonal antibody specific for a TCR V beta 8 determinant. Moreover, when cell-free TH products were bound to and eluted from immobilized F23.1, these affinity-purified materials had antigen-specific and major histocompatibility complex-restricted helper activity that synergized with recombinant lymphokines in the generation of B cell antibody responses. These findings suggest that the factor isolated from T cell supernatants is a cell-free form of the TCR alpha beta dimer.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Guy, R -- Ullrich, S J -- Foo-Philips, M -- Hathcock, K S -- Appella, E -- Hodes, R J -- New York, N.Y. -- Science. 1989 Jun 23;244(4911):1477-80.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Experimental Immunology Branch, National Cancer Institute, Bethesda, MD 20892.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2472009" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antibodies, Monoclonal ; Antigens/*immunology ; B-Lymphocytes/immunology ; Disulfides ; Epitopes/immunology ; Hemocyanin/immunology ; Histocompatibility Antigens/immunology ; Immunoglobulin G/immunology ; Immunosorbent Techniques ; Interleukin-2/pharmacology ; Interleukin-4 ; Interleukins/pharmacology ; Lymphocyte Activation ; Macromolecular Substances ; Mice ; Molecular Weight ; Receptors, Antigen, T-Cell/*immunology/isolation & purification ; Recombinant Proteins ; Serum Albumin, Bovine/immunology ; T-Lymphocytes, Helper-Inducer/*immunology ; Trinitrobenzenes/immunology
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  • 77
    Publication Date: 1989-10-27
    Description: Host cell factors act together with regulatory genes of the human immunodeficiency virus (HIV) to control virus production. Human-Chinese hamster ovary hybrid cell clones were used to probe for human chromosomes involved in regulating HIV gene expression. DNA transfection experiments showed that 4 of 18 clones had high levels of HIV gene expression measured by both extracellular virus production and transactivation of the HIV long terminal repeat in the presence of the trans-activator (tat) gene. Karyotype analyses revealed a 94% concordance (17/18) between human chromosome 12 and HIV gene expression. Other chromosomes had an 11 to 72% concordance with virus production.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hart, C E -- Ou, C Y -- Galphin, J C -- Moore, J -- Bacheler, L T -- Wasmuth, J J -- Petteway, S R Jr -- Schochetman, G -- New York, N.Y. -- Science. 1989 Oct 27;246(4929):488-91.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Centers for Disease Control, Atlanta, GA 30333.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2683071" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Chloramphenicol O-Acetyltransferase/genetics ; *Chromosomes, Human, Pair 12 ; Cricetinae ; Cricetulus ; Gene Expression Regulation, Viral/*genetics ; Genes, tat ; HIV-1/*genetics ; Humans ; Hybrid Cells ; Repetitive Sequences, Nucleic Acid ; Transcriptional Activation
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  • 78
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-05-26
    Description: In isolated heart cells, beta-adrenergic receptor stimulation induced a background current that was suppressed by simultaneous muscarinic receptor stimulation. Direct activation of adenylate cyclase with forskolin also elicited this current, suggesting regulation by adenosine 3',5'-monophosphate (cAMP). This current could be recorded when sodium, calcium, and potassium currents were eliminated by channel antagonists or by ion substitution. Alteration of the chloride equilibrium potential produced changes in the reversal potential expected for a chloride current. Activation of this chloride current modulated action potential duration and altered the resting membrane potential in a chloride gradient-dependent manner.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Harvey, R D -- Hume, J R -- HL30143/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1989 May 26;244(4907):983-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physiology, University of Nevada School of Medicine, Reno 89557.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2543073" target="_blank"〉PubMed〈/a〉
    Keywords: Acetylcholine/pharmacology ; Action Potentials/drug effects ; Adenylyl Cyclases/metabolism ; Animals ; Chloride Channels ; Chlorides/*physiology ; Colforsin/pharmacology ; Cyclic AMP/physiology ; Electric Conductivity ; Enzyme Activation/drug effects ; Guinea Pigs ; Heart/*physiology ; Isoproterenol/pharmacology ; Membrane Potentials/drug effects ; Membrane Proteins/*physiology ; Propranolol/pharmacology ; Receptors, Adrenergic, beta/drug effects/*physiology ; Receptors, Muscarinic/physiology ; Ventricular Function
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  • 79
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-01-20
    Description: Nerve growth factor (NGF) interacts with both high affinity (Kd = 10(-10)-10(-11)M) and low affinity (Kd = 10(-8)-10(-9)M) receptors; the binding of NGF to the high affinity receptor is correlated with biological actions of NGF. To determine whether a single NGF binding protein is common to both forms of the receptor, a full-length receptor cDNA was introduced in the NR18 cell line, an NGF receptor-deficient variant of the PC12 pheochromocytoma cell line. The transformant displayed (i) both high and low affinity receptors detectable by receptor binding; (ii) an affinity cross-linking pattern with 125I-labeled NGF similar to that of the parent PC12 cell line; and (iii) biological responsiveness to NGF as assayed by induction of c-fos transcription. These findings support the hypothesis that a single binding protein is common to both forms of the NGF receptor and suggest that an additional protein is required to produce the high affinity form of the NGF receptor.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hempstead, B L -- Schleifer, L S -- Chao, M V -- HD23315/HD/NICHD NIH HHS/ -- NS-21072/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1989 Jan 20;243(4889):373-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Hematology/Oncology, Cornell University Medical College, New York, NY 10021.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2536190" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Blotting, Northern ; Cloning, Molecular ; Gene Expression Regulation ; Nerve Growth Factors/pharmacology ; Pheochromocytoma ; Proto-Oncogene Proteins/genetics ; Proto-Oncogene Proteins c-fos ; Rats ; Receptors, Cell Surface/*genetics/metabolism ; Receptors, Nerve Growth Factor ; Transformation, Genetic ; Tumor Cells, Cultured
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  • 80
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-06-23
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Holden, C -- New York, N.Y. -- Science. 1989 Jun 23;244(4911):1437.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2499929" target="_blank"〉PubMed〈/a〉
    Keywords: *Animal Welfare ; Animals ; Euthanasia/*veterinary ; *Haplorhini ; *Legislation, Veterinary ; National Institutes of Health (U.S.) ; United States
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  • 81
    Publication Date: 1989-06-30
    Description: A neuron that is an integral member of the pyloric neural network of the lobster stomatogastric nervous system leaves this network and instead fires exclusively with another stomatogastric nervous system network, the cardiac sac network, whenever the cardiac sac network is active. This switch is associated with the neuron losing, in a long-lasting fashion, regenerative oscillatory membrane properties that underlie its participation in the pyloric network. Functional membership of neurons in central networks is thus not fixed, and long-lasting neuromodulatory influences, controlled at least in part by sensory inputs, can switch neurons from one network to another.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hooper, S L -- Moulins, M -- New York, N.Y. -- Science. 1989 Jun 30;244(4912):1587-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratoire de Neurobiologie et Physiologie Comparees, Universite de Bordeaux, Arcachon, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2740903" target="_blank"〉PubMed〈/a〉
    Keywords: Action Potentials ; Animals ; Cell Membrane/physiology ; Electric Stimulation ; Membrane Potentials ; Nephropidae/*physiology ; Nervous System/cytology ; *Nervous System Physiological Phenomena ; Neural Pathways/cytology/physiology ; Neurons/*physiology ; Stomach/innervation
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  • 82
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-03-17
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hoyt, J A -- New York, N.Y. -- Science. 1989 Mar 17;243(4897):1419-20.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2928775" target="_blank"〉PubMed〈/a〉
    Keywords: *Animal Welfare ; Animals ; Animals, Laboratory
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  • 83
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-03-24
    Description: The N-methyl-D-aspartate (NMDA) class of excitatory amino acid receptors regulates the strength and stability of excitatory synapses and appears to play a major role in excitotoxic neuronal death associated with stroke and epilepsy. The conductance increase gated by NMDA is potentiated by the amino acid glycine, which acts at an allosteric site tightly coupled to the NMDA receptor. Indole-2-carboxylic acid (I2CA) specifically and competitively inhibits the potentiation by glycine of NMDA-gated current. In solutions containing low levels of glycine, I2CA completely blocks the response to NMDA, suggesting that NMDA alone is not sufficient for channel activation. I2CA will be useful for defining the interaction of glycine with NMDA receptors and for determining the in vivo role of glycine in excitotoxicity and synapse stabilization.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Huettner, J E -- HL-35034/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1989 Mar 24;243(4898):1611-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Neurobiology, Harvard Medical School, Boston, MA 02115.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2467381" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Aspartic Acid/*analogs & derivatives/physiology ; Cells, Cultured ; Electric Conductivity ; Glycine/*antagonists & inhibitors ; In Vitro Techniques ; Indoles/*pharmacology ; Ion Channels/drug effects ; N-Methylaspartate ; Neural Inhibition ; Rats ; Receptors, N-Methyl-D-Aspartate ; Receptors, Neurotransmitter/*drug effects ; Structure-Activity Relationship
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  • 84
    Publication Date: 1989-12-22
    Description: The murine acquired immunodeficiency syndrome is induced by a defective retrovirus. To study the role of virus replication in this disease, helper-free stocks of defective Duplan virus were produced. These stocks were highly pathogenic in absence of detectable replicating murine leukemia viruses (MuLVs) other than xenotropic MuLV. They induced expansion of the infected cell population (over 1000-fold), and this cell expansion was oligoclonal in origin and, most likely, arose through cell division. These results suggest that this defective virus is oncogenic, inducing a primary neoplasia associated with an acquired immunodeficiency syndrome as a paraneoplastic syndrome. These data emphasize the need to determine whether virus replication is necessary for the progression of other immunodeficiency diseases, including acquired immunodeficiency syndrome, and whether these diseases also represent paraneoplastic syndromes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Huang, M -- Simard, C -- Jolicoeur, P -- New York, N.Y. -- Science. 1989 Dec 22;246(4937):1614-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Molecular Biology, Clinical Research Institute of Montreal, Quebec, Canada.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2480643" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Blotting, Southern ; Cells, Cultured ; DNA, Viral/isolation & purification ; Defective Viruses/isolation & purification/*pathogenicity ; Helper Viruses/isolation & purification ; Immunologic Deficiency Syndromes/*microbiology ; Leukemia Virus, Murine/pathogenicity ; Lymph Nodes/microbiology ; Lymphocytes/microbiology ; Mice ; Mice, Inbred C57BL ; RNA-Directed DNA Polymerase/analysis ; Retroviridae/isolation & purification/*pathogenicity ; Retroviridae Infections/*microbiology ; Spleen/microbiology
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  • 85
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-07-28
    Description: The CD4 and CD8 T cell receptor accessory molecules can both be isolated from T lymphocytes in association with p56lck, a membrane-associated, cytoplasmic tyrosine protein kinase that is expressed exclusively in lymphoid cells. The enzymatic activity of p56lck may therefore be regulated by CD4 and CD8 and be important in antigen-induced T cell activation. Exposure of human T cells and some mouse T cells to the tumor promoter 12-O-tetradecanoyl phorbol-13-acetate (TPA), an activator of protein kinase C, caused the dissociation of p56lck and CD4. Activation of protein kinase C may therefore interrupt regulation of p56lck by CD4 and alter the ability of p56lck to interact with polypeptide substrates. In contrast, exposure of cells to TPA did not cause dissociation of p56lck and CD8. Regulation of p56lck by CD4 may therefore differ from regulation by CD8.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hurley, T R -- Luo, K -- Sefton, B M -- New York, N.Y. -- Science. 1989 Jul 28;245(4916):407-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Molecular Biology and Virology Laboratory, Salk Institute, San Diego, CA 92138.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2787934" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antigens, Differentiation, T-Lymphocyte/*immunology ; Cell Line ; Enzyme Activation ; Humans ; Leukemia, T-Cell ; Lymphocyte Specific Protein Tyrosine Kinase p56(lck) ; Phosphorylation ; Precipitin Tests ; Protein Kinase C/*metabolism ; Protein-Tyrosine Kinases/*metabolism ; T-Lymphocytes/*immunology ; Tetradecanoylphorbol Acetate/pharmacology ; Tumor Cells, Cultured
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  • 86
    Publication Date: 1989-12-08
    Description: A novel bacteriophage lambda vector system was used to express in Escherichia coli a combinatorial library of Fab fragments of the mouse antibody repertoire. The system allows rapid and easy identification of monoclonal Fab fragments in a form suitable for genetic manipulation. It was possible to generate, in 2 weeks, large numbers of monoclonal Fab fragments against a transition state analog hapten. The methods described may supersede present-day hybridoma technology and facilitate the production of catalytic and other antibodies.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Huse, W D -- Sastry, L -- Iverson, S A -- Kang, A S -- Alting-Mees, M -- Burton, D R -- Benkovic, S J -- Lerner, R A -- New York, N.Y. -- Science. 1989 Dec 8;246(4935):1275-81.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology, Research Institute of Scripps Clinic, La Jolla, CA 92037.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2531466" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Antibodies, Monoclonal/*biosynthesis/genetics ; Antibody Specificity ; Antigen-Antibody Reactions ; Bacteriophage lambda/*genetics ; Base Sequence ; Cloning, Molecular/methods ; Escherichia coli/genetics ; Gene Amplification ; Gene Library ; *Genetic Vectors ; Hemocyanin/analogs & derivatives/immunology ; Immunoglobulin Fab Fragments/biosynthesis ; Immunoglobulin Fragments/*biosynthesis/genetics ; Mice ; Molecular Sequence Data ; Organophosphorus Compounds/immunology ; Recombinant Proteins/biosynthesis/genetics
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  • 87
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-09-22
    Description: Long-term potentiation (LTP) is a model for learning and memory processes. Tetanic stimulation of the sensory cortex produces LTP in motor cortical neurons, whereas tetanization of the ventrolateral nucleus of the thalamus, which also projects to the motor cortex, does not. However, after simultaneous high-frequency stimulation of both the sensory cortex and the ventrolateral nucleus of the thalamus, LTP of thalamic input to motor cortical neurons is induced. This associative LTP occurs only in neurons in the superficial layers of the motor cortex that receive monosynaptic input from both the sensory cortex and the ventrolateral nucleus of the thalamus. Associative LTP in the motor cortex may constitute a basis for the retention of motor skills.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Iriki, A -- Pavlides, C -- Keller, A -- Asanuma, H -- NS-08626/NS/NINDS NIH HHS/ -- NS-10705/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1989 Sep 22;245(4924):1385-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Rockefeller University, New York, NY 10021.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2551038" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Brain Mapping ; Cats ; Electric Stimulation ; Learning/physiology ; Motor Cortex/*physiology ; *Motor Skills ; Somatosensory Cortex/physiology ; Synaptic Transmission ; Thalamic Nuclei/physiology
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  • 88
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-03-10
    Description: Tension and intracellular free calcium concentration [( Ca2+]i) were measured simultaneously in single smooth muscle cells isolated from the anterior byssus retractor muscle (ABRM) of Mytilus edulis that were loaded with the fluorescent Ca2+ indicator fura-2. Electrical stimulation evoked a transient elevation of [Ca2+]i associated with a "catch" contraction. During the catch state, however, [Ca2+]i was effectively at its resting level and was unaffected by 5-hydroxytryptamine, which induced a rapid relaxation from catch. The results indicate that a maintained high [Ca2+]i is not required for the maintenance of catch tension in intact ABRM and that there was no significant change in [Ca2+]i upon abolition of catch.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ishii, N -- Simpson, A W -- Ashley, C C -- Wellcome Trust/United Kingdom -- New York, N.Y. -- Science. 1989 Mar 10;243(4896):1367-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Zoological Institute, Faculty of Science, University of Tokyo, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2922614" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Benzofurans ; Bivalvia ; Calcium/*physiology ; Fluorescent Dyes ; Fura-2 ; In Vitro Techniques ; *Muscle Contraction ; Muscle, Smooth/*physiology ; Spectrometry, Fluorescence/instrumentation/methods
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  • 89
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-03-03
    Description: Monoclonal antibodies have been induced that are capable of catalyzing specific hydrolysis of the Gly-Phe bond of peptide substrates at neutral pH with a metal complex cofactor. The antibodies were produced by immunizing with a Co(III) triethylenetetramine (trien)-peptide hapten. These antibodies as a group are capable of binding trien complexes of not only Co(III) but also of numerous other metals. Six peptides were examined as possible substrates with the antibodies and various metal complexes. Two of these peptides were cleaved by several of the antibodies. One antibody was studied in detail, and cleavage was observed for the substrates with the trien complexes of Zn(II), Ga(III), Fe(III), In(III), Cu(II), Ni(II), Lu(III), Mg(II), or Mn(II) as cofactors. A turnover number of 6 x 10(-4) per second was observed for these substrates. These results demonstrate the feasibility of the use of cofactor-assisted catalysis in an antibody binding site to accomplish difficult chemical transformations.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Iverson, B L -- Lerner, R A -- New York, N.Y. -- Science. 1989 Mar 3;243(4895):1184-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology, Research Institute of Scripps Clinic, La Jolla, CA 92037.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2922606" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; *Antibodies, Monoclonal ; Antigens/immunology ; Binding Sites, Antibody ; Catalysis ; Chemical Phenomena ; Chemistry ; Cobalt/immunology/metabolism ; Glycine/metabolism ; Haptens/immunology ; Hydrogen-Ion Concentration ; Hydrolysis ; Immunization ; Metals/metabolism ; Mice ; Molecular Sequence Data ; Molecular Structure ; Oligopeptides/*metabolism ; Phenylalanine/metabolism ; Trientine/immunology
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  • 90
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-04-28
    Description: The specific hydrolysis of unactivated esters bearing an R or S enantiomeric alcohol has been achieved by two separate classes of catalytic antibodies induced to bind either the R or S substrates. The antibodies exhibit rate accelerations (10(3) to 10(5] above background hydrolysis that, coupled with their antipodal specificity, provide a novel set of reagents for use in synthesis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Janda, K D -- Benkovic, S J -- Lerner, R A -- New York, N.Y. -- Science. 1989 Apr 28;244(4903):437-40.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology, Research Institute of Scripps Clinic, La Jolla, CA 92037.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2717936" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Antibodies, Monoclonal/immunology ; Antibody Specificity ; Antigens/immunology ; Benzyl Alcohols/metabolism ; *Catalysis ; Esters/metabolism ; Haptens ; Hemocyanin/immunology ; Hydrolysis ; Immunization ; Kinetics ; Lipase/*metabolism ; Mice ; Mice, Inbred A ; Molecular Structure ; Organophosphonates/immunology ; Stereoisomerism ; Substrate Specificity
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  • 91
    Publication Date: 1989-05-12
    Description: Although the immunologic role of T cells bearing the conventional alpha beta T cell receptor (TCR) has been well characterized, little is known about the function of the population of T cells bearing the gamma delta TCR. Therefore, the role of gamma delta T cells in the immune response to Mycobacterium tuberculosis (MT) was investigated. The number of TCR gamma delta cells in the draining lymph nodes of mice immunized with MT was greatly increased in comparison with the number of TCR alpha beta cells. Three biochemically distinct gamma delta TCRs were detected. Analyses of cell cycle, of interleukin-2 receptor expression, and of interleukin-2 responsiveness showed that a large proportion of the gamma delta T cells were activated in vivo. TCR gamma delta cells responded to solubilized MT antigens in vitro but, in contrast to MT-specific alpha beta T cells, the response of gamma delta T cells to MT did not require major histocompatability complex class II recognition. These results provide an example of antigen-specific activation of gamma delta T cells in vivo and indicate that gamma delta T cells may have a distinct role in generating a primary immune response to certain microorganisms.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Janis, E M -- Kaufmann, S H -- Schwartz, R H -- Pardoll, D M -- New York, N.Y. -- Science. 1989 May 12;244(4905):713-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Cellular and Molecular Immunology, National Institutes of Health, Bethesda, MD 20892.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2524098" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antigens, Bacterial/*immunology ; Antigens, CD3 ; Antigens, CD8 ; Antigens, Differentiation, T-Lymphocyte/analysis ; Cell Count ; Cell Cycle ; Electrophoresis, Polyacrylamide Gel ; Flow Cytometry ; Histocompatibility Antigens Class II/immunology ; Immunosorbent Techniques ; Interleukin-2/pharmacology ; Lymph Nodes/cytology ; *Lymphocyte Activation ; Macromolecular Substances ; Mice ; Mycobacterium tuberculosis/*immunology ; Receptors, Antigen, T-Cell/analysis/*immunology ; Receptors, Interleukin-2/metabolism ; T-Lymphocytes/cytology/*immunology
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  • 92
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-09-29
    Description: The CA1 pyramidal neurons in the hippocampus contain a high density of adrenal corticosteroid receptors. By intracellular recording, CA1 neurons in slices from adrenalectomized rats have been found to display a markedly reduced afterhyperpolarization (that is, the hyperpolarizing phase after a brief depolarizing current pulse) when compared with their sham controls. No differences were found for other tested membrane properties. Brief exposure of hippocampal slices from adrenalectomized rats to glucocorticoid agonists, 30 to 90 minutes before recording, greatly enhanced the afterhyperpolarization. In addition, glucocorticoids attenuated the norepinephrine-induced blockade of action potential accommodation in CA1 neurons. The findings indicate that glucocorticoids can reduce transmitter-evoked excitability in the hippocampus, presumably via a receptor-mediated genomic action.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Joels, M -- de Kloet, E R -- New York, N.Y. -- Science. 1989 Sep 29;245(4925):1502-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Molecular Neurobiology, University of Utrecht, The Netherlands.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2781292" target="_blank"〉PubMed〈/a〉
    Keywords: Action Potentials/drug effects ; Adrenalectomy ; Animals ; Glucocorticoids/*pharmacology ; Hippocampus/cytology/*drug effects ; In Vitro Techniques ; Membrane Potentials/drug effects ; Neurons/cytology/drug effects ; Norepinephrine/*pharmacology ; Rats
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  • 93
    Publication Date: 1989-10-06
    Description: The tyrosine kinase pp60v-src, encoded by the v-src oncogene, seems to regulate phosphatidylinositol metabolism. The effect of pp60v-src on control points in inositol phosphate production was examined by measuring the amounts of inositol polyphosphates in Rat-1 cells expressing wild-type or mutant forms of the protein. Expression of v-src-resulted in a five- to sevenfold elevation in the steady-state amount of an isomer of inositol tetrakisphosphate, whereas the concentrations of inositol trisphosphates or other inositol tetrakisphosphates were not affected. The activity of a key enzyme in the formation of inositol tetrakisphosphates, inositol (1,4,5)-trisphosphate 3-kinase, was increased six- to eightfold in cytosolic extracts prepared from the v-src-transformed cells, suggesting that this enzyme may be one target for the pp60v-src kinase and that it may participate in the synthesis of novel, higher order inositol phosphates.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Johnson, R M -- Wasilenko, W J -- Mattingly, R R -- Weber, M J -- Garrison, J C -- CA-39076/CA/NCI NIH HHS/ -- CA-40042/CA/NCI NIH HHS/ -- DK-19952/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1989 Oct 6;246(4926):121-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pharmacology, University of Virginia School of Medicine, Charlottesville 22908.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2506643" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cell Line, Transformed ; Fibroblasts/metabolism ; Inositol Phosphates/*metabolism ; Isomerism ; Oncogene Protein pp60(v-src) ; Protein-Tyrosine Kinases/metabolism ; Rats ; Retroviridae Proteins/*physiology ; Sugar Phosphates/*metabolism
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  • 94
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-05-19
    Description: Biochemical and electrophysiological studies suggest that odorants induce responses in olfactory sensory neurons via an adenylate cyclase cascade mediated by a G protein. An olfactory-specific guanosine triphosphate (GTP)-binding protein alpha subunit has now been characterized and evidence is presented suggesting that this G protein, termed Golf, mediates olfaction. Messenger RNA that encodes Golf alpha is expressed in olfactory neuroephithelium but not in six other tissues tested. Moreover, within the olfactory epithelium, Golf alpha appears to be expressed only by the sensory neurons. Specific antisera were used to localize Golf alpha protein to the sensory apparatus of the receptor neurons. Golf alpha shares extensive amino acid identity (88 percent) with the stimulatory G protein, Gs alpha. The expression of Golf alpha in S49 cyc- kin- cells, a line deficient in endogenous stimulatory G proteins, demonstrates its capacity to stimulate adenylate cyclase in a heterologous system.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Jones, D T -- Reed, R R -- New York, N.Y. -- Science. 1989 May 19;244(4906):790-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Department of Molecular Biology and Genetic Johns Hopkins School of Medicine, Baltimore, MD 21205.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2499043" target="_blank"〉PubMed〈/a〉
    Keywords: Adenylyl Cyclases/metabolism ; Amino Acid Sequence ; Animals ; Base Sequence ; Cloning, Molecular ; GTP-Binding Proteins/analysis/genetics/*physiology ; Gene Expression Regulation ; Immunoblotting ; Immunohistochemistry ; Molecular Sequence Data ; Neurons, Afferent/analysis/*physiology ; *Odors ; Olfactory Bulb/physiology ; Olfactory Mucosa/analysis/*innervation ; RNA, Messenger/analysis/genetics ; Rats ; Sequence Homology, Nucleic Acid ; *Signal Transduction ; Tissue Distribution ; Transfection
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    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 95
    Publication Date: 1989-06-09
    Description: Voltage-dependent Ca2+ channels (VDCCs) are modulators of synaptic plasticity, oscillatory behavior, and rhythmic firing in brain regions such as the hippocampus. The distribution and lateral mobility of VDCCs on CA1 hippocampal neurons have been determined with biologically active fluorescent and biotinylated derivatives of the selective probe omega-conotoxin in conjunction with circular dityndallism, digital fluorescence imaging, and photobleach recovery microscopy. On noninnervated cell bodies, VDCCs were found to be organized in multiple clusters, whereas after innervation the VDCCs were concentrated and immobilized at synaptic contact sites. On dendrites, VDCC distribution was punctate and was interrupted by extensive bare regions or abruptly terminated. More than 85% of the dendritic VDCCs were found to be immobile by fluorescence photobleach recovery. Thus, before synaptic contact, specific mechanisms target, segregate, and immobilize VDCCs to neuronal cell bodies and to specialized dendritic sites. Regulation of this distribution may be critical in determining the firing activity and integrative properties of hippocampal CA1 neurons.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Jones, O T -- Kunze, D L -- Angelides, K J -- NS01218/NS/NINDS NIH HHS/ -- NS23575/NS/NINDS NIH HHS/ -- NS24606/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1989 Jun 9;244(4909):1189-93.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physiology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2543080" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Calcium Channel Blockers/*pharmacology ; Calcium Channels/drug effects/*physiology ; Cells, Cultured ; Electric Conductivity ; Hippocampus/*physiology ; Membrane Potentials/drug effects ; Mollusk Venoms/*pharmacology ; Neurons/drug effects/*physiology ; Pyramidal Tracts/*physiology ; *omega-Conotoxins
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 96
    Publication Date: 1989-09-15
    Description: Gene targeting via homologous recombination-mediated disruption in murine embryonic stem (ES) cells has been described for a number of different genes expressed in these cells; it has not been reported for any nonexpressed genes. Pluripotent stem cell lines were isolated with homologously recombined insertions at three different loci: c-fos, which is expressed at a low level in ES cells, and two genes, adipsin and adipocyte P2 (aP2), which are transcribed specifically in adipose cells and are not expressed at detectable levels in ES cells. The frequencies at which homologous recombination events occurred did not correlate with levels of expression of the targeted genes, but did occur at rates comparable to those previously reported for genes that are actively expressed in ES cells. Injection of successfully targeted cells into mouse blastocysts resulted in the formation of chimeric mice. These studies demonstrate the feasibility of altering genes in ES cells that are expressed in a tissue-specific manner in the mouse, in order to study their function at later developmental stages.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Johnson, R S -- Sheng, M -- Greenberg, M E -- Kolodner, R D -- Papaioannou, V E -- Spiegelman, B M -- DK 31405/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1989 Sep 15;245(4923):1234-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Dana-Farber Cancer Institute, Boston, MA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2506639" target="_blank"〉PubMed〈/a〉
    Keywords: Adipose Tissue/cytology ; Animals ; Blotting, Northern ; Blotting, Southern ; Carrier Proteins/biosynthesis/*genetics ; Cell Line ; Chimera ; Complement Factor D ; DNA, Recombinant ; DNA-Binding Proteins/biosynthesis/genetics ; Fatty Acid-Binding Proteins ; Fatty Acids/metabolism ; *Gene Expression Regulation ; Genetic Vectors ; Mice ; *Neoplasm Proteins ; *Nerve Tissue Proteins ; Proto-Oncogene Proteins/biosynthesis/*genetics ; Proto-Oncogene Proteins c-fos ; RNA, Messenger/biosynthesis/genetics ; *Recombination, Genetic ; Serine Endopeptidases/*genetics ; Stem Cells/*metabolism ; Transfection
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 97
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-05-05
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Jukes, T H -- New York, N.Y. -- Science. 1989 May 5;244(4904):515.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2717938" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Dimethylhydrazines/adverse effects ; *Fruit ; Herbicides ; Humans ; Neoplasms/*chemically induced ; Plant Growth Regulators ; Succinates/*adverse effects
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    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 98
    Publication Date: 1989-06-02
    Description: Neurotransmitter receptors are usually restricted to neuronal cells, but the signaling pathways activated by these receptors are widely distributed in both neural and non-neural cells. The functional consequences of activating a brain-specific neurotransmitter receptor, the serotonin 5HT1c receptor, in the unnatural environment of a fibroblast were examined. Introduction of functional 5HT1c receptors into NIH 3T3 cells results, at high frequency, in the generation of transformed foci. Moreover, the generation and maintenance of transformed foci requires continued activation of the serotonin receptor. In addition, the injection of cells derived from transformed foci into nude mice results in the generation of tumors. The serotonin 5HT1c receptor therefore functions as a protooncogene when expressed in NIH 3T3 fibroblasts.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Julius, D -- Livelli, T J -- Jessell, T M -- Axel, R -- New York, N.Y. -- Science. 1989 Jun 2;244(4908):1057-62.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Molecular Biophysics, College of Physicians and Surgeons, Columbia University, New York, NY 10032.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2727693" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Calcium/pharmacology ; Cell Division ; Cell Line ; *Cell Transformation, Neoplastic ; Cloning, Molecular ; Fibroblasts/metabolism ; *Gene Expression Regulation ; Genetic Vectors ; Mice ; Mice, Nude ; Neoplasm Transplantation ; Receptors, Serotonin/*genetics/physiology ; Second Messenger Systems ; Serotonin/pharmacology/physiology ; Transfection
    Print ISSN: 0036-8075
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 99
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1989-01-20
    Description: DNA and nuclear proteins were transferred into cells simultaneously at more than 95% efficiency by means of vesicle complexes. The DNA was rapidly transported into the nuclei of cultured cells, and its expression reached a maximum within 6 to 8 hours after its introduction. Moreover, when the plasmid DNA and nuclear protein were cointroduced into nondividing cells in rat liver by injection into the portal veins of adult rats, the plasmid DNA was carried into liver cell nuclei efficiently by nuclear protein. The expression of the DNA in adult rat liver, on introduction of the DNA with nuclear protein, was more than five times as great as with nonnuclear protein.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kaneda, Y -- Iwai, K -- Uchida, T -- New York, N.Y. -- Science. 1989 Jan 20;243(4889):375-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute for Molecular and Cellular Biology, Osaka University, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2911748" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Blotting, Northern ; Cell Compartmentation ; Cell Nucleus/metabolism ; Cells, Cultured ; DNA/*metabolism/pharmacokinetics ; High Mobility Group Proteins/*metabolism ; Liver/*metabolism ; Mice ; Rats ; Transformation, Genetic
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 100
    Publication Date: 1989-12-22
    Description: A human acute lymphoblastic leukemia (ALL) cell line that was transplanted into immune-deficient SCID mice proliferated in the hematopoietic tissues, invaded various organs, and led to the death of the mice. The distribution of leukemic cells in SCID mice was similar to the course of the disease in children. A-1 cells marked with a retrovirus vector showed clonal evolution after the transplant. SCID mice that were injected with bone marrow from three patients with non-T ALL had leukemic cells in their bone marrow and spleen. This in vivo model of human leukemia is an approach to understanding leukemic growth and progression and is a novel system for testing new treatment strategies.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kamel-Reid, S -- Letarte, M -- Sirard, C -- Doedens, M -- Grunberger, T -- Fulop, G -- Freedman, M H -- Phillips, R A -- Dick, J E -- New York, N.Y. -- Science. 1989 Dec 22;246(4937):1597-600.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Genetics, Hospital for Sick Children, Toronto, Ontario.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2595371" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Brain/pathology ; Cell Line ; Clone Cells ; DNA, Neoplasm/isolation & purification ; Humans ; Immunologic Deficiency Syndromes/*pathology ; Kidney/pathology ; Liver/pathology ; Mice ; Mice, Mutant Strains ; Neoplasm Transplantation ; Precursor Cell Lymphoblastic Leukemia-Lymphoma/*pathology ; Transplantation, Heterologous
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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