spopsisWater vapor sorption isotherms of cotton cellulose and B pattern starch preparations, potato starch, corn amylose, amylomaize, and retrograded potato starch, were determined at 5 and 25°C. The crystallinity fraction of these materials equilibrated with water vapor at various partial pressures was determined by x-ray diffraction. The thermodynamic functions of adsorption were calculated, and B.E.T. constants were determined.As has been pointed out by Macchia and Bettelheim,' there is surprisingly little published work on the sorption of water vapor by starch in view of potentially wide industrial interest. At the time we initiated these studies, no water adsorption data on B pattern starch had been published. Subsequently results for the B form of amylose have appeared.l, In the present work, our previous studies on the interaction of water and pectic substances2-4 and water and starch6 by x-ray and isotherm methods are hereby extended to the B pattern starch preparations: potato starch, corn amylose, amylomaize, and retrograded potato starch. In addition we have made studies on cotton cellulose for the purpose of comparison. ExperimentalThe samples were prepared in the manner we have recently reportedq6 For the adsorption studies, the samples were predried in vacuum at room temperature until constant weight was reached (about 1 week). After adsorption, the samples were dried in vacuum at 70°C. for a period of 7-10 days to obtain a dry weight.

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This investigation aims to measure the structural changes of direct foreign investment in the economic sectors and its relationship with the agricultural sector, and the impact of direct foreign agricultural investment and some macroeconomic variables on economic growth in Egypt during the period 2007-2017. Regression analysis, some descriptive statistical indicators, graphical presentation methods and the annual growth rate were applied based on the secondary data published by the official authorities. The findings show a negative relationship between the foreign investment ratio coefficients in the industrial and the agricultural sector which reflects a replacement relationship between them and a positive relationship with other sectors in a way that reflects the complementarily of the relationship between them. There are weakness and ineffectiveness of the impact foreign investment in the agricultural sector compared to the impact of agricultural exports on the economic growth, which confirms the inability of the agricultural sector to attract foreign investors. This stud y recommends the importance of making direct foreign investment as a full partner in the Egyptian economy development and not an integral component by applying best practices in the field of reforming the business environment by promoting the principle of transparency of statistical, financial and economic information within the framework of governance, and legalization of the informal economy, and raising the efficiency of the institutional and administrative framework.

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