Agricultural Marketing in Tropical Africa: Obstacles to Systematic Study

2018 ◽  
pp. 1-18 ◽  
Author(s):  
H. Laurens van der Laan
Keyword(s):  
Systematic Study ◽  
Tropical Africa ◽  
Agricultural Marketing

Food-Crop Marketing Boards in Tropical Africa

1987 ◽  
Vol 25 (3) ◽  
pp. 375-402 ◽  
Author(s):  
William O. Jones
Keyword(s):  
World War Ii ◽  
Great Depression ◽  
Food Crop ◽  
World War ◽  
Tropical Africa ◽  
Agricultural Marketing ◽  
The Past ◽  
The Great Depression ◽  
African Populations ◽  
Made In

Agricultural marketing boards in tropical Africa are heirlooms of the Great Depression and World War II, when colonial governments found their principal sources of revenue severely reduced and both European and African populations financially distressed. Marketing boards are of British origin, but similar efforts were made in French and Belgian Africa. The rationale for intervention is clouded; some of the principal reasons have faded into the past or were never openly expressed.1

Quantitative parallel EELS spectrum imaging developed as a new tool in AEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1202-1203
Author(s):  
Gianluigi Botton ◽  
Gilles L'espérance
Keyword(s):  
Statistical Analysis ◽  
Spatial Resolution ◽  
Personal Computer ◽  
Systematic Study ◽  
Present Author ◽  
Chemical Elements ◽  
Detection Limits ◽  
Research Groups ◽  
Quantitative Performance ◽  
Spectrum Imaging

As interest for parallel EELS spectrum imaging grows in laboratories equipped with commercial spectrometers, different approaches were used in recent years by a few research groups in the development of the technique of spectrum imaging as reported in the literature. Either by controlling, with a personal computer both the microsope and the spectrometer or using more powerful workstations interfaced to conventional multichannel analysers with commercially available programs to control the microscope and the spectrometer, spectrum images can now be obtained. Work on the limits of the technique, in terms of the quantitative performance was reported, however, by the present author where a systematic study of artifacts detection limits, statistical errors as a function of desired spatial resolution and range of chemical elements to be studied in a map was carried out The aim of the present paper is to show an application of quantitative parallel EELS spectrum imaging where statistical analysis is performed at each pixel and interpretation is carried out using criteria established from the statistical analysis and variations in composition are analyzed with the help of information retreived from t/γ maps so that artifacts are avoided.

A SYSTEMATIC STUDY OF 2s2 2pk - 2s2pk+l - 2pk+2 TRANSITIONS IN MULTIPLY-CHARGED Cl IONS.

1979 ◽  
Vol 40 (C1) ◽  
pp. C1-208-C1-210 ◽  
Author(s):  
J. P. Forester ◽  
D. J. Pegg ◽  
P. M. Griffin ◽  
G. D. Alton ◽  
S. B. Elston ◽  
...  
Keyword(s):  
Systematic Study ◽  
Multiply Charged

The solubility of calcium carbonate  in green liquor handling systems

TAPPI Journal ◽  
2019 ◽  
Vol 18 (10) ◽  
pp. 595-602
Author(s):  
ALISHA GIGLIO ◽  
VLADIMIROS G. PAPANGELAKIS ◽  
HONGHI TRAN
Keyword(s):  
Calcium Carbonate ◽  
Systematic Study ◽  
Kraft Pulp ◽  
Thermodynamic Simulation ◽  
Solubility Data ◽  
Pulp Mills ◽  
Persistent Problem ◽  
Green Liquor ◽  
Kraft Pulp Mills ◽  
Salt Systems

The formation of hard calcite (CaCO3) scale in green liquor handling systems is a persistent problem in many kraft pulp mills. CaCO3 precipitates when its concentration in the green liquor exceeds its solubility. While the solubility of CaCO3 in water is well known, it is not so in the highly alkaline green liquor environment. A systematic study was conducted to determine the solubility of CaCO3 in green liquor as a function of temperature, total titratable alkali (TTA), causticity, and sulfidity. The results show that the solubility increases with increased temperature, increased TTA, decreased causticity, and decreased sulfidity. The new solubility data was incorporated into OLI (a thermodynamic simulation program for aqueous salt systems) to generate a series of CaCO3 solubility curves for various green liquor conditions. The results help explain how calcite scale forms in green liquor handling systems.

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