CRI Values Research Articles

Effect of deacetylation time on the preparation, properties and swelling behavior of chitosan films

The effect of time during the deacetylation of chitin by hot alkali was studied to ascertain the film forming ability of chitosan. Five types of chitosan films were prepared in a single step deacetylation process by varying the alkaline treatment time from 2 to 10 h. The degree of deacetylation (DD) of chitosan and chitosan films were characterized using Fourier transform infrared spectroscopy (FT-IR) and elemental (CHN) analysis methods. The DD was found not to vary significantly beyond 2 h of deacetylation and the DD values by CHN analysis was higher than by FT-IR method. The degree of crystallinity (crystallinity index, CrI) of the chitosan films was also evaluated by X-ray powder diffraction method and the film prepared with 2 h deacetylation showed lower CrI. The morphology of this film by scanning electron microscopy (SEM) shows homogeneous and continuous structure. Swelling index of the films was measured in phosphate buffer solution at physiological conditions and film prepared with 2 h deacetylation showed maximum swelling index. However, the film formed with 6 h deacetylation process has the highest DD with higher CrI and low contact angle values. This film seems to be more suitable for biomedical applications.

Parameters for optimization of coke quality (CRI and CSR)

Experimental data illustrate the diversity of ash composition in Russian coal, even within a single rank. Examples show that the ash basicity may be used for effective optimization of the coking-batch composition by basin, rank, and components, in improving the CRI and CSR values of coke.

Preliminary estimation of coke’s CRI and CSR values on the basis of the physical properties of coal ash

The relation between the physical properties of coal ash and the CRI and CSR values of coke is established. It is suggested that increase in the mean molecular mass of coal ash increases the reactivity and disintegration of coke pieces in tests according to the ISO 18894:2006 (E) standard.

Optimizing the coking coal employed at OAO NTMK to ensure competitive CSR and CRI values of coke

Optimizing the coking coal employed at OAO NTMK to ensure competitive CSR and CRI values of coke

High School Biology Students' Knowledge and Certainty about Diffusion and Osmosis Concepts

The purpose of this study was to investigate students' understanding about scientifically acceptable content knowledge by exploring the relationship between knowledge of diffusion and osmosis and the student's certainty in their content knowledge. Data was collected from a high school biology class with the Diffusion and Osmosis Diagnostic Test (DODT) and Certainty of Response (CRI) scale. All data was collected after completion of a unit of study on diffusion and osmosis. The results of the DODT were dichotomized into correct and incorrect answers, and CRI values were dichotomized into certain and uncertain. Values were used to construct a series of 2 × 2 contingency tables for each item on the DODT and corresponding CRI. High certainty in incorrect answers on the DODT indicated tenacious misconceptions about diffusion and osmosis concepts. Low certainty in incorrect or correct answers on the DODT indicated possible guessing; and, therefore no understanding, or confusion about their understanding. Chi‐square analyses revealed that significantly more students had misconceptions than desired knowledge on content covering the Influence of Life Forces on Diffusion and Osmosis, Membranes, the Particulate and Random Nature of Matter, and the Processes of Diffusion and Osmosis. Most students were either guessing or had misconceptions about every item related to the concepts osmosis and tonicity. Osmosis and diffusion are important to understanding fundamental biology concepts, but the concept of tonicity not be introduced to high school biology students until effective instructional approaches can be identified by researchers.