scholarly journals Development of a continuous evaporation system for an API solution stream prior to crystallization

2021 ◽  
Author(s):  
Phillip Roche ◽  
Roderick Jones ◽  
Brian Glennon ◽  
Philip Donnellan
Keyword(s):  
Steady State ◽  
Bubble Column ◽  
Feed Stream ◽  
Continuous Processing ◽  
Processing Mode ◽  
Model Predictions ◽  
Measured Effect ◽  
Predicted Values ◽  
Rate Of Evaporation ◽  
General Method

A bubble column was investigated as a method to achieve a desired and controllable rate of evaporation of a pharmaceutical solution in continuous processing mode. Applying a developed thermodynamic model to predict the rate of evaporation, all predicted values achieved accuracies within the bounds of instrumentation errors. The model accounted for the measured effect of reduced vapor pressure caused by dissolved solids as a function of their concentration. A general method to obtain accurate measurement of this effect is introduced and applied, improving the accuracy of model predictions. Predicting the rate of evaporation using the developed model, consistent and repeatable evaporation rates ranging from 0.7–6.9 g/min were achieved. Applying the column as a controllable evaporator, the concentration of a dilute feed stream was increased in a single equilibrium stage and coupled to a crystallizer. The configured system achieved a steady state of controllable operation over a duration of 5 hours

Construction and Experimental Study of an Elevation Linear Fresnel Reflector

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
J. D. Nixon ◽  
P. A. Davies
Keyword(s):  
Heat Loss ◽  
Thermal Efficiency ◽  
Theoretical Models ◽  
Loss Coefficient ◽  
Heat Transfer Fluid ◽  
Stagnation Temperature ◽  
Model Predictions ◽  
The Difference ◽  
Predicted Values ◽  
Linear Fresnel Reflector

This paper outlines a novel elevation linear Fresnel reflector (ELFR) and presents and validates theoretical models defining its thermal performance. To validate the models, a series of experiments were carried out for receiver temperatures in the range of 30–100 °C to measure the heat loss coefficient, gain in heat transfer fluid (HTF) temperature, thermal efficiency, and stagnation temperature. The heat loss coefficient was underestimated due to the model exclusion of collector end heat losses. The measured HTF temperature gains were found to have a good correlation to the model predictions—less than a 5% difference. In comparison to model predictions for the thermal efficiency and stagnation temperature, measured values had a difference of −39% to +31% and 22–38%, respectively. The difference between the measured and predicted values was attributed to the low-temperature region for the experiments. It was concluded that the theoretical models are suitable for examining linear Fresnel reflector (LFR) systems and can be adopted by other researchers.

Stratospheric ozone depletion - an overview of the scientific debate

1995 ◽  
Vol 19 (1) ◽  
pp. 1-17 ◽  
Author(s):  
Frances Drake
Keyword(s):  
Ozone Depletion ◽  
Stratospheric Ozone ◽  
Ozone Layer ◽  
Scientific Uncertainty ◽  
Perceived Threat ◽  
Stratospheric Ozone Depletion ◽  
Scientific Debate ◽  
Supersonic Transport ◽  
Model Predictions ◽  
Predicted Values

For almost half a century it was widely believed that the photochemistry of the stratosphere and hence ozone distribution were well understoood. As observations revealed a gap between observed and predicted values it was recognized that a number of substances acted as catalysts thereby increasing the destruction of ozone and that humanity could augment those catalysts and affect the ozone layer. Initial concern focused on nitrogen oxides from the exhausts of supersonic transport, but attention switched in the mid-1970s to chlorofluorocarbons (CFCs). Although the theory of anthropogenic ozone depletion by CFCs found widespread scientific support the perceived threat was minimized in particular by successive model predictions downgrading the amount of depletion. The appearance of the ozone hole over Antarctica in the mid-1980s reopened the debate as to whether such depletion was anthropogenic or natural in origin. It also highlighted the model's inadequate treatment of the processes occurring in the stratosphere and the importance of dynamics and radiative transfer in stratospheric ozone destruction. Scientific consensus again favours the anthropogenic depletion of the ozone layer. In conclusion it is considered that the degree of consensus outweighs the image of scientific uncertainty that is often portrayed in relation to the issue of stratospheric ozone depletion.

A General Approach to the Practical Solution of Creep Problems

1959 ◽  
Vol 81 (4) ◽  
pp. 585-594 ◽  
Author(s):  
A. Mendelson ◽  
M. H. Hirschberg ◽  
S. S. Manson
Keyword(s):  
Steady State ◽  
Stress Distribution ◽  
Temperature Gradient ◽  
Successive Approximations ◽  
Appreciable Effect ◽  
Rotating Disks ◽  
Transient Conditions ◽  
Practical Solution ◽  
State Stress ◽  
General Method

A general method is presented for the solution of creep problems by the use of successive approximations. The method is equally applicable to different creep laws and loading paths. Examples are presented for the creep in a flat plate with a temperature gradient and for several cases of rotating disks. In these disk problems the transient conditions prior to the establishment of steady-state stress distribution are included and shown to have an appreciable effect on the total creep strains. The use of different cumulative creep laws such as the time-hardening and strain-hardening laws are illustrated.

scholarly journals The accumulation of amino acids by mouse ascites-tumour cells. Dependence on but lack of equilibrium with the sodium-ion electrochemical gradient

1981 ◽  
Vol 194 (2) ◽  
pp. 415-426 ◽  
Author(s):  
C Hacking ◽  
A A Eddy
Keyword(s):  
Amino Acids ◽  
Steady State ◽  
Amino Acid ◽  
Rate Coefficient ◽  
Tumour Cells ◽  
Cellular Respiration ◽  
Mouse Ascites ◽  
Predicted Values ◽  
Leak Pathway ◽  
Ascites Tumour Cells

1. The fluorescent dye 3,3′-dipropyloxadicarbocyanine was used to show that the tumour cells absorbed 2-aminoisobutyrate, glycine, L-leucine and L-isoleucine and certain other amino acids electrogenically. The Km values with respect to amino acid concentration ([A]o), obtained from the fluorescence assays, varied through the above series from 0.8 to 26 mM, with Vmax. fairly constant. 2. Similar Km values described the uptake of the 14C-labelled amino acids in five instances where this was measured. 3. Each amino acid lowered the membrane potential (E) by 10-20 mV when its cellular concentration ([A]i) had reached a steady value and [A]o was 10mM. In these experiments energy metabolism was maintained by glycolysis, 2,4-dinitrophenol was present and cellular respiration was inhibited. The corresponding net flow of amino acid through the Na+ symport was deduced by making use of the fact that the depolarization an amino acid initially caused was roughly proportional to the net influx of amino acid itself. 4. The steady-state depolarization was attributed to the presence of a leak pathway for the amino acid with a rate coefficient PA. As assayed in the absence of Na+, PA was about 5-fold larger for isoleucine than for glycine. 5. Direct estimates of Vmax./PA were similar to those inferred from the extent of depolarization in the steady state and [A]i. 6. A mathematical model was used to predict [A]i/[A]o in term of the measured values of [Na]o, [Na]i, E, Km and Vmax./PA. The predicted and observed values agreed fairly well when [A]o was 1 mM or 10 mM. 7. [A]i/[A]o varied from about 2.5 for 10 mM-isoleucine to 30 for 1 mM-2-aminoisobutyrate when delta microNa, expressed as a ratio, was ostensibly in the range 19-43. 8. The concentration of 2-aminoisobutyrate from a 0.1 mM solution in the presence or absence of ouabain was consistent with the model, whereas the concentration of isoleucine from a 0.1 mM solution exceeded the predicted values 2-5-fold. 9. The tumour cells concentrated 2-amino-bicyclo[2,2,1]heptane-2-carboxylic acid by a non-electrogenic mechanism, with which isoleucine may also interact.

Sodic soil reclamation: Modelling and field study

Soil Research ◽  
2001 ◽  
Vol 39 (6) ◽  
pp. 1225 ◽  
Author(s):  
Donald L. Suarez
Keyword(s):  
Management Practices ◽  
Drainage System ◽  
Water Model ◽  
Soil Reclamation ◽  
Sodium Absorption ◽  
Sodic Soils ◽  
Sodium Absorption Ratio ◽  
Model Predictions ◽  
Predicted Values ◽  
Almost Continuous

Reclamation of sodic soils has traditionally been undertaken using calculation of gypsum or Ca requirement assuming 100% exchange efficiency and neglect of the contribution of calcium carbonate in the profile. The UNSATCHEM model is reviewed and then evaluated for its ability to predict field reclamation of a sodic saline soil. The 40-ha field site was initially at an electrical conductivity (EC) of 50 dS/m and a sodium absorption ratio (SAR) of 144 in the top 30 cm. After installation of a drainage system, 24 Mg/ha of gypsum was applied to a depth of 15 cm in the soil. Subsequently, 114 cm of water was applied by almost continuous ponding for 3 months. Model simulations were made based on infiltration of 70–80 cm of water, correcting for the estimated evaporation of 41 cm of water. These infiltration estimates are consistent with the good fit between the measured Cl concentrations after reclamation and the model predicted values after 70–80 cm of infiltrated water. Model predictions of EC and SAR after reclamation gave a satisfactory fit to the measured values. The effectiveness of mixing gypsum to various depths was evaluated in terms of the predicted SAR profiles. Alternative management practices of green manuring in presence of calcite were simulated and appeared feasible. In this instance it appears likely that the field could have been reclaimed either with less water or without the addition of gypsum.

Cyanide oxidation by ozone in a steady-state flow bubble column

2006 ◽  
Vol 19 (2) ◽  
pp. 117-122 ◽  
Author(s):  
F. Barriga-Ordonez ◽  
F. Nava-Alonso ◽  
A. Uribe-Salas
Keyword(s):  
Steady State ◽  
Bubble Column ◽  
Steady State Flow ◽  
State Flow ◽  
Cyanide Oxidation

Thermal Stresses in Transversely Isotropic Semi-Infinite Elastic Solids

1958 ◽  
Vol 25 (1) ◽  
pp. 86-88
Author(s):  
Brahmadev Sharma
Keyword(s):  
Thermal Stress ◽  
Steady State ◽  
Thermal Stresses ◽  
Elastic Solid ◽  
Transversely Isotropic ◽  
Elastic Solids ◽  
Stress Problem ◽  
Method Of Solution ◽  
General Method

Abstract A general method of solution of the steady-state thermal-stress problem of a transversely isotropic semi-infinite elastic solid is given in this paper.

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