HPTLC-Densitometric Analysis of Candesartan Cilexetil and Hydrochlorothiazide in Tablets

JPC – Journal of Planar Chromatography – Modern TLC - A simple, rapid and precise high-performance thin-layer chromatographic (HPTLC) method for analysis of candesartan cilexetil and...     

Applying NAEP to Improve Mathematics Content and Methods Courses for Preservice Elementary and Middle School Teachers

This study explored how mathematics content and methods courses for preservice elementary and middle school teachers could be improved through the integration of a set of instructional materials based on the National Assessment of Educational Progress (NAEP). A set of eight instructional modules was developed and tested. The study involved 7 university instructors and 542 preservice teachers (PSTs) from three different universities. A quasi‐experimental nonequivalent groups design was used for this study in which the following data sources were collected and analyzed. Three versions of a Learning Mathematics for Teaching test were given to assess PSTs‘ mathematical content knowledge for teaching: (a) Elementary Number Concepts and Operations—Content Knowledge; (b) Elementary Geometry—Content Knowledge; and (c) Middle School Number Concepts and Operations—Content Knowledge. In addition, the Mathematics Teacher Efficacy Beliefs Instrument was given to assess PSTs’ teacher efficacy beliefs. Test results were analyzed using paired samples t‐tests. Findings suggest that use of instructional materials, based on NAEP, with PSTs results in increases in their mathematical content knowledge for teaching and in their teaching efficacy beliefs.     

Polymer networks in dentistry

Polymer networks applied in clinical dentistry can be divided into two groups: (i) hard, solid two-and threedimensional crosslinked structures formed during photo-curing of dental polymeric filling compositions, and (ii) soft, hydrogel-type of networks based on polymeric ionic complexes, used for the tightening of microchannels in teeth. The first group is based on crosslinked di- and trifunctional monomers, and on solid poly(acrylic acid) - inorganic glasses (“glass - ionomer cements”) This group has found wide clinical applications, in spite of many disadvantages such as susceptibility towards hydrolytic, mechanical. bio- and enzymatic degradations, and contents of toxic, allergenic and mutagenic components. The second group, the soft-hydrogel type of networks, has been investigated and developed at our institute in order to tighten channels in teeth. The microchannels, with a diameter of 30–200Å in enamel and 1–3 μm in dentine, are filled with a loose, native bio-hydrogel of protein origin. Hydrogels have the ability to swell in water of biological fluids present in the oral cavity, and can retain a significant fraction of fluid within the structure. Decreasing pH below 5.5 causes a slow dissolution of the hydroxyapatite crystals in the walls of the microchannels with a consequent widening of their lumens. Metabolites and toxins from microorganisms, which are always present in the oral cavity, can penetrate into these enlarged channels and cause inflammatory reactions in the underlying pulp tissue. In order to decrease fluid flow and inhibit penetration of microorganisms, but still allow diffusion of ions and water, we have developed and tested polymeric hydrogels based on poly(acrylic acid) and metal salts, and chitosan, which can be formed directly in the micro-channels of dental hard tissues.