We have used infrared spectroscopy, ellipsometry, and contact angle measurements to study self-assembled monolayer (SAM) formation on aluminum native oxide from three alkanephosphonic acids:  CF3(CF2)7(CH2)11PO3H2 (F8H11PA), and CH3(CH2) n PO3H2 (n = 15 (H16PA); n = 21 (H22PA)). These compounds show significant differences in film structure and film formation kinetics. Strikingly, the methylene segment of the semifluorinated F8H11PA SAM never reaches an ordered state even at long assembly times. This contrasts with the ordered chains in equilibrium films from H16PA and H22PA. We attribute this behavior to steric effects of the fluorocarbon segment and the phosphonic acid headgroup. F8H11PA represents an amphiphile in which bulky head and tail groups prevent an interposed hydrocarbon segment from ordering. For all three phosphonic acids, negative peaks attributed to loss of Al−OH groups in the infrared spectra of the monolayers are consistent with a condensation reaction between the acids and surface hydroxyls to form bound aluminophosphonate salts. With respect to kinetics, our results indicate that F8H11PA approaches its equilibrium film structure considerably faster than the hydrocarbon phosphonic acids. We interpret the structural dependence of film formation kinetics in terms of the T c formalism advanced by Rondelez and co-workers (Langmuir 1994, 10, 4367−4373). We also suggest that the accelerated film formation exhibited by F8H11PA may be due to chain entanglement and solubility effects, to the extent that this species may self-assemble as islands of approximately vertically oriented chains which fill in as coverage increases. H22PA may also deposit as islands, but in contrast, film formation for H16PA probably involves initially disordered chains with higher tilt angles that order and reorient as film assembly proceeds.

PurposesThe aims of the study are to identify factors contributing to computed tomography (CT) trauma scan turnaround time variation and to evaluate the effects of an automated intervention on time metrics.MethodsThroughput metrics were captured via picture archiving and communication system from January 1, 2018, to December 16, 2019, and included 17,709 CT trauma scans from our institution. Initial data showed that imaging technologist variation played a significant role in trauma imaging turnaround time. In December 2019, we implemented a 2-pronged intervention: (1) educational intervention to techs and (2) modified trauma CT abdomen/pelvis to autogenerate and autosend reformats to picture archiving and communication system. A total of 13,169 trauma CT scans were evaluated from the postintervention period taking place from January 2020 to March 2021. Throughput metrics such as last image to first report interval and emergency department length of stay were captured and compared with performing technologist, time of day, and weekday versus weekend scans.ResultsSubstantial variability among trauma CT scans was observed. For CT trauma abdomen/pelvis, the interval from last image to initial report decreased from 26.4 to 24.0 minutes (P = 0.001) while the interval between first and last image time decreased from 11.4 to 4.2 minutes (P < 0.001). Emergency department length of stay also decreased from 3.9 to 3.7 hours (P < 0.0001) in the postintervention period. Variation among imaging technologist was statistically significant and became less significant after intervention (P = 0.09, P = 0.54)ConclusionsFactors such as imaging technologist variability, time of day, and day of the week of trauma scans played a significant role in CT trauma turnaround time variability. Automation interventions can help with efficiency in image turnaround time.

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