Disentangling the effects of unobserved factors on seatbelt use choices in multi-occupant vehicles

Despite the proven effectiveness of seatbelt use in reducing traffic casualties, not wearing a seatbelt still contributes to a substantial proportion of fatal crashes worldwide. This problem has raised the need to better understand factors contributing to seatbelt use, particularly in multi-occupant vehicles. Among these factors, behavioural determinants of seatbelt use are difficult to measure and their data are not readily available. These behavioural factors may have shared influences on vehicle occupants, causing their seatbelt use choices to be correlated. These complexities have prevented a comprehensive understanding of seatbelt use choices in the literature. This study aims to fill this gap by developing an econometric model that explains seatbelt use choices in multi-occupant vehicles. A set of binary logit models are constructed for seatbelt use choices and their utilities are correlated across vehicle occupants. A new latent variable representing the unobserved factors or ‘atmosphere’ of the vehicle is then incorporated into the model. The model is empirically tested using seatbelt use data from Tennessee, United States. Results indicate that vehicle body type and time of the day are significantly associated with seatbelt use. In addition, the collective seatbelt use in a vehicle is influenced by the unobserved atmosphere in the vehicle. Age, alcohol and drug consumption, higher proportion of old population and white racial mix, higher income per capita, and higher education levels are factors contributing to this latent atmosphere.Safety and Security Scienc

Morphological and Surface Potential Characterization of Protein Nanobiofilm Formation on Magnesium Alloy Oxide: Their Role in Biodegradation

The formation of a protein nanobiofilm on the surface of degradable biomaterials such as magnesium (Mg) and its alloys influences metal ion release, cell adhesion/spreading, and biocompatibility. During the early stage of human body implantation, competition and interaction between inorganic species and protein molecules result in a complex film containing Mg oxide and a protein layer. This film affects the electrochemical properties of the metal surface, the protein conformational arrangement, and the electronic properties of the protein/Mg oxide interface. In this study, we discuss the impact of various simulated body fluids, including sodium chloride (NaCl), phosphate-buffered saline (PBS), and Hanks' solutions on protein adsorption, electrochemical interactions, and electrical surface potential (ESP) distribution at the adsorbed protein/Mg oxide interface. After 10 min of immersion in NaCl, atomic force microscopy (AFM) and scanning Kelvin probe force microscopy (SKPFM) showed a higher surface roughness related to enhanced degradation and lower ESP distribution on a Mg-based alloy than those in other solutions. Furthermore, adding bovine serum albumin (BSA) to all solutions caused a decline in the total surface roughness and ESP magnitude on the Mg alloy surface, particularly in the NaCl electrolyte. Using SKPFM surface analysis, we detected a protein nanobiofilm (∼10-20 nm) with an aggregated and/or fibrillary morphology only on the Mg surface exposed in Hanks' and PBS solutions; these surfaces had a lower ESP value than the oxide layer.Materials Science and EngineeringTeam Yaiza Gonzalez GarciaTeam Arjan Mo

Challenges and Strategies for Optimizing Corrosion and Biodegradation Stability of Biomedical Micro- and Nanoswimmers: A Review

The last two decades have witnessed the emergence of micro- and nanoswimmers (MNSs). Researchers have invested significant efforts in engineering motile micro- and nanodevices to address current limitations in minimally invasive medicine. MNSs can move through complex fluid media by using chemical fuels or external energy sources such as magnetic fields, ultrasound, or light. Despite significant advancements in their locomotion and functionalities, the gradual deterioration of MNSs in human physiological media is often overlooked. Corrosion and biodegradation caused by chemical reactions with surrounding medium and the activity of biological agents can significantly affect their chemical stability and functional properties during their lifetime performance. It is therefore essential to understand the degradation mechanisms and factors that influence them to design ideal biomedical MNSs that are affordable, highly efficient, and sufficiently resistant to degradation (at least during their service time). This review summarizes recent studies that delve into the physicochemical characteristics and complex environmental factors affecting the corrosion and biodegradation of MNSs, with a focus on metal-based devices. Additionally, different strategies are discussed to enhance and/or optimize their stability. Conversely, controlled degradation of non-toxic MNSs can be highly advantageous for numerous biomedical applications, allowing for less invasive, safer, and more efficient treatments.Materials Science and EngineeringTeam Yaiza Gonzalez GarciaTeam Arjan Mo

Albumin Protein Impact on Early-Stage In Vitro Biodegradation of Magnesium Alloy (WE43)

Mg and its alloys are promising biodegradable materials for orthopedic implants and cardiovascular stents. The first interactions of protein molecules with Mg alloy surfaces have a substantial impact on their biocompatibility and biodegradation. We investigate the early-stage electrochemical, chemical, morphological, and electrical surface potential changes of alloy WE43 in either 154 mM NaCl or Hanks’ simulated physiological solutions in the absence or presence of bovine serum albumin (BSA) protein. WE43 had the lowest electrochemical current noise (ECN) fluctuations, the highest noise resistance (Zn = 1774 Ω·cm2), and the highest total impedance (|Z| = 332 Ω·cm2) when immersed for 30 min in Hanks’ solution. The highest ECN, lowest Zn (1430 Ω·cm2), and |Z| (49 Ω·cm2) were observed in the NaCl solution. In the solutions containing BSA, a unique dual-mode biodegradation was observed. Adding BSA to a NaCl solution increased |Z| from 49 to 97 Ω·cm2 and decreased the ECN signal of the alloy, i.e., the BSA inhibited corrosion. On the other hand, the presence of BSA in Hanks’ solution increased the rate of biodegradation by decreasing both Zn and |Z| while increasing ECN. Finally, using scanning Kelvin probe force microscopy (SKPFM), we observed an adsorbed nanolayer of BSA with aggregated and fibrillar morphology only in Hanks’ solution, where the electrical surface potential was 52 mV lower than that of the Mg oxide layer.Materials Science and EngineeringTeam Yaiza Gonzalez GarciaTeam Arjan Mo