Alginate/Ni−Al-layered double hydroxide/dye (Alg/Ni−Al-LDH/dye) composite films were fabricated using the solution casting method. The dyes used included methyl red, phenol red, thymol blue, bromothymol blue, m-cresol purple, methyl orange, bromocresol purple (BP), and bromocresol green (BG) in the overall pH range of 3.8 to 9.6. The chemical composition and morphology of the Alg/Ni−Al-LDH/dye composite film structure were investigated by Fourier transform infrared spectroscopy, FESEM, atomic force microscopy, and X-ray diffraction. The Alg/Ni−Al-LDH/dye composite films were semitransparent and mechanically flexible. Acetic acid was investigated as a respiratory biomarker related to gastrointestinal diseases. The parameters studied included color volume, response time, Ni−Al-LDH nanosheet volume, reusability, and drawing of the calibration curve along with statistical features including standard deviation, relative standard deviation, limit of detection, and limit of quantitation. Colorimetric indicators BP and BG in the presence of acetic acid produce color changes that are almost visible to the naked eye. However, other used indicators have shown almost no change. Therefore, it can be reported that the sensors made in the presence of BP and BG act selectively in relation to acetic acid.

Green Mountain diatreme is at the southern end of a belt of about 90 kimberlite plutons along the eastern margin of the Laramie and Front Ranges extending from Iron Mountain, Wyoming, to near Boulder, Colorado. Fission-track ages have been obtained both from sphene and apatite from the Green Mountain pluton. The apatite age, 77.1 ± 5 m.y., apparently is a reset age, representative of when the rock mass last underwent sufficient cooling to retard fission-track annealing. The cooling event is likely associated with erosional strip­ ping during and following the Laramide Orogeny. The sphene age of 367 ± 15 m.y. (Devonian) appears to represent the time of emplacement of the pluton. The fact that this value is statistically identical with the radio­ metric age of the Schaffer No. 3 pipe, near the Colorado-Wyoming State line, supports the idea that all of the kimberlite plutons were intruded during one plutonic episode in Devonian time.

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