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Aim: Ulcerative colitis (UC) is a chronic, idiopathic, relapsing inflammatory disease of the gastrointestinal tract. In recent years, biochemical parameters have been widely used to determine the disease activity of UC. The present study aimed to determine the relationship between the prognostic nutritional index (PNI), systemic immune-inflammation index (SII), and disease activity. Material and Method: All adult patients followed in the IBD unit of the Ankara City Hospital Gastroenterology Department between March 1st, 2019, and March 31st, 2021, were included in this retrospective study. We analyzed the relationship between the SII, PNI, and the endoscopic severity of UC. In addition, PNI and SII were compared between the active and remission group. Disease activity was described by the Rachmilewitz endoscopic activity index (EAI). Results: The study group consisted of 402 patients. One hundred sixty-five of these patients were in the endoscopic remission group, and 237 were in the endoscopically active group. SII, NLR, and PLR values were significantly higher in the active UC group, and PNI values exhibited a lower mean than inactive UC patients (p<0.05 for all parameters). In addition, the NLR, PLR, and SII were positively, and PNI was negatively correlated with the endoscopic activity index (respectively, R=0.29, R=0.24, R=0.38, R=-0.32; and for all parameters, p<0.001). Conclusion: PNI and SII were significantly associated with UC activity. PNI and SII may be useful tools for assessing disease activity in UC. [ABSTRACT FROM AUTHOR]

A framework using peridynamic theory is developed and demonstrated for deformation and failure analysis of carbon nanotube (CNT) yarn-based structural composites. Experimental work involved tension testing of a CNT yarn/polymer composite resulting in stress–strain response up to and including failure. The as-prepared specimen was characterized using x-ray micro computed tomography (CT), which was then converted into voxel-based data with CNT yarn, polymer, and void phases as well as surface undulation. A Density-Based Spatial Clustering of Applications with Noise algorithm was applied to detect and quantify the clusters of voids, of CNT-rich, and of resin-rich regions. The voxel data, with all microstructural details, were used in peridynamic simulations. These demonstrate the critical roles of resin and void clusters and surface undulation in fracture initiation and propagation. Additional analysis was performed to construct probability density functions (PDFs) of different phases (yarn, resin, and void) with the goal of constructing synthetic virtual composite specimens. The synthetically reconstructed peridynamic models correctly captured the experimental stress–strain response. The similarities and differences between the failure (initiation and propagation) behaviors predicted by x-ray CT-based and PDF-based peridynamic model simulations are presented in detail and discussed. [ABSTRACT FROM AUTHOR]