# crystSG: Relative Crystallinity Calculation of X-Ray Diffraction... In cryst: Calculate the Relative Crystallinity of Starch by XRD and FTIR

## Description

Allow to calculate the relative crystallinity of starch by XRD. The basic concept of Frost approach involves obtaining a smoothed line that separates the amorphous and crystalline starch of an X-ray diffraction pattern. This smoothed line is achieved by applying a Savitzky-Golay smoothing method to the original pattern.

## Usage

 `1` ```crystSG(pattern, N = 101, iter = 400, p = 2) ```

## Arguments

 `pattern` matrix. The matrix of X-ray diffraction pattern. The first row corresponds to Bragg angle 2θ; the second row corresponds to intensity. `N` numeric. N length of the smoothing window (number of variables). Defaults to 101. `iter` numeric. Iter number of iterations. Defaults to 400. `p` numeric. Filter order. Defaults to 2.

## Details

Calculate the relative starch crystallinity of XRD pattern by Frost method.

## Value

An object of class crystSG, which is a list with the following components:

 `original` Original matrix of X-ray diffraction patterns. `background` Estimation of the background shape (curve of the amorphous starch). `corrected` Estimation of residual crystalline area (curve of the crystalline starch). `summary` Summary calculation of crystallinity. Total area under the curve of the diffraction pattern (A.U.); Amorphous area (A.U.); Crystalline area (A.U.); Relative crystallinity (%).

## Author(s)

Claudio Pozo Valenzuela [aut, cre] and Saddys Rodriguez-llamazares [aut]

## References

Frost, K., et al. (2009). "Crystallinity and structure of starch using wide angle X-ray scattering." Carbohydrate Polymers 78(3): 543-548.

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13``` ```data(XRD) # Convert data frame to matrix, select A-type starch pattern <- as.matrix(t(XRD[, c("Bragg_angle","A")])) # List of crystallinity components crs <- crystSG(pattern, N = 101, iter = 400, p = 2) # Original matrix original <- crs\$original # Background shape background <- crs\$background # Curve of the crystalline starch corrected <- crs\$corrected # Summary calculation of crystallinity summary <- crs\$summary ```

### Example output

```Loading required package: flux