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ZSM-22 was synthesized using various sources of
silica, organic template 1,6-diaminohexane, under hydrothermal conditions, with
and without agitation during crystallization. Subsequently, the crystallized
material was used as seeds to accelerate the crystallization process.
Characterization of the ZSM-22 samples was performed by XRD, ATG/DTG and FT-IR.
It was found that it is possible to synthesize ZSM-22 employing colloidal
silica and pyrolytic silica as silicon sources only if the system is stirred
during crystallization. The crystallization time for these systems was 13
hours, longer times of crystallization do not significantly increase the
crystallinity of the sample. The addition of seeds significantly accelerates
the crystallization of ZSM-22, reducing the crystallization time to only 7
hours, with stirring and with systems employing colloidal silica.
Information asymmetries are an important
element in the functioning of capital markets. An indirect means of measuring
information asymmetry is through the spread of stock prices. The purpose of
this paper is to identify the explanatory variables and the determinants of the
bid-ask spread and to quantify the influence that the actors involved in the
brokering of publically offered securities may have over the spread. The
methodology used to model the time series for each of the analyzed companies is
based on a time series from each of the observed econometric multivariate
processes. The analysis shows a significantly negative relationship between the
spread and the market-maker size, calculated in terms of both the equity and
the stock portfolio; likewise, activity is measured by observing the amount
offered for purchase and/or sale.