Acta Universitaria

9-16

Authors: Brenda Ponce Lira, Araceli Ortiz Polo, Elena María Otazo Sánchez, Edilso Reguera Ruiz, Otilio Arturo Acevedo Sandoval, Francisco Prieto Garcia, César Abelardo Gonzalez Ramírez

Tezontle is an extrusive volcanic rock, coming in black or red in color. Despite its many uses and applications, there are few studies concerning the attributes of this rock. Therefore, this work to the physical characterization of red tezontle samples, taken from Tlahuelilpan, Hidalgo, Mexico. After grinding and sieving, the following properties were obtained: humidity (0.37% to 0.48%), weighed moisture-retention capacity (7.50% – 43.56%) and volumetric mois­ture-retention capacity (5% – 25%), which justifies its hydroponic and gardening uses; particle density (2.37 g cm-3 - 2.83 g cm-3), dry bulk density (0.87 g cm-3 - 1.33 g cm-3), total pore space (52.83% - 63.90 %), specific surface area (5.558 m2 g-1 and 9.66 m2 g-1) and cation exchange capacity (4.04 Cmol(+) kg-1), whose low values contradict the high efficiency reported for cation removal. The preliminary analysis of the X-ray diffraction pattern shows intense peaks of quartz and suggests the presence of plagioclases (anorthite and albite).

30-36

Authors: Rosa María Mariscal-Moreno, Eduardo Betanzo-Quezada

The current state of the economy has led companies to seek advantages over their com­petitors, proposing tools with the aim of reducing the uncertainty of the supply chain. In this paper was developed and applied an empirical method to evaluate the reliability of the supply chain for a feed mill company through an analysis and development of a math­ematical model. The supply chain was analyzed to detect its risk factors totaling 29 fac­tors, 11 of them considered of high risk because of their frequency and impact. Integrating the 29 factors in an equation, we estimated the reliability, obtaining an overall value of 65.20%. The method can be used to measure the supply chain reliability.