Date of Award

4-2024

Degree Name

Doctor of Philosophy

Department

Chemical and Paper Engineering

First Advisor

James R. Springstead, Ph.D.

Second Advisor

Qing Liu Wu, Ph.D.

Third Advisor

Mert Atilhan, Ph. D.

Fourth Advisor

John. M. Spitsbergen, Ph. D.

Keywords

Active clay, methylene blue, monocyte recruitment pathway, oxidized phospholipids, OxPAPC, spectrophotometer

Abstract

Precise measurement of active clay content in molding sand is essential in the metal casting foundry to produce high quality end products with no defects. The historical methylene blue (MB) test was considered qualitative, subjective and prone to operator bias in regard to the reading of the halo. A new spectrophotometric or digital clay technique has been developed. The test utilizes the cation exchange capabilities of the Cu(II)-triethylenetetramine dye and the absorbance reading of the sequestered solution through a UV-Vis spectrophotometer. Working with multiple laboratories (Decher, MTI, EJ, and JD) on actual foundry green sand samples, the method was optimized in 3 stages. The finalized method includes cation ion exchange mixing of green sand and Cu(II)-triethylenetetramine dye, separation of the sequestered dye through a syringe filter and CEC measurement via UV-Vis Spectrophotometer. The test data and the GR&R study demonstrated better variability, accuracy and a consistent trend compared to the MB test. The digital clay technique requires minimal training, has a low startup and labor cost, and low run time. This testing method has been submitted to be accepted into the AFS standard test for active clay in green sands and to be featured in the AFS Mold & Core Test Handbook. Additionally, a new optimized method is being optimized to measure total clay in foundry green sands. These methods will improve efficiency and process control in metal casting, helping propel the industry into Foundry 4.0, a new era in metal casting that will be defined improved process control, by generally transitioning from hands-on labor measurement to utilizing automated CEC or measuring instruments.

Additional work in this study includes elucidation of the pathway by which oxidized lipids affect the monocyte recruitment pathway and ultimately regulate atherosclerosis, an underlying condition that may lead to heart attack or stroke. OxPAPC has been shown to emulate the molecular effects of LDL, including the regulation of more than 1,000 genes in human aortic endothelial cells (HAEC). Isoprostanes, neuroprostanes and neurofurans are derived from polyunsaturated fatty acids though non-enzymatic peroxidation and it is hypothesized that these lipids may act like OxPAPC and regulate monocytes and other genes which cause atherosclerosis. Among these lipids, the results confirm findings from previous studies that 15-F2t-isoprostane induces monocyte binding and regulates inflammatory and oxidative stress. Treatment of 15-F2t-isoprostane with HAECs shows consistent results as previously reported from Leitinger, 2001 upregulating genes MCP-1, IL-8 and HO-1. Treatment of 4-epi-4-F3t-neuroprostane shows downregulation of all genes MCP-1, IL-8 and HO-1, while 4(RS)-ST-Δ5-8-neurofuran treatment shows downregulation of IL-8 and MCP-1, potentially suggesting that they exhibit EC barrier enhancement capabilities. The broader impact of this research will help to develop a novel approach towards understanding atherosclerosis and assist medical professionals in developing novel drug treatments and diagnostic tools to prevent or suppress atherosclerosis lesions or inflammation.

Access Setting

Dissertation-Open Access

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