Modelling and experimental characterization of nanoindentation responses of various biocomposite materials

PhD ThesisIn the past decades, composite materials (which are usually classified into fibre-reinforced composites and particle-reinforced composites, depending on the geometry of the reinforcements) have been widely applied in tissue engineering as implant scaffolds. A lot of work has been done on the bulk mechanical properties of these composites. However, there is lack of nanomechanical characterization of such composites, which is crucial for understanding the cell-material interactions at small scale, and further optimizing the design of scaffold materials to promote the formation of new viable tissue. Nanoindentation has been used for nanomechanical characterization of a wide range of composite materials, but there is lack of comprehensive modelling of these composites. Therefore, this thesis begins with the modelling of the nanomechanics of inclusion-reinforced composite materials. In this part, finite element analysis (FEA) is adopted to study the spatial-dependent mechanical response of fibre/matrix and particle/matrix composites. The effects of various factors (such as inclusion geometry, indenter geometry, inclusion orientation and relative indentation location) on the nanomechanical response are studied. Various indentation-based empirical or semi-analytical models have been examined and novel analytical models are proposed to describe the nanomechanical behaviour of these inclusion-reinforced composites. Towards the end of this thesis, the nanoindentation characterization of typical biocomposite materials is presented, namely extracellular matrix. For these complex composites, the existing analytical models may not be directly applied. However, with the aid of a statistical model and FEA, it has been demonstrated that mechanical properties of each individual component can be determined

Synthesis of Dinitrogen‐Fused Spirocyclic Heterocycles via Organocatalytic 1,3‐dipolar Cycloaddition of 2‐Arylidene‐1,3‐indandiones and an Azomethine Imine

An efficient 1,3‐dipolar cycloaddition of 2‐arylidene‐1,3‐indandiones with an azomethine imine has been developed to furnish spiroindane‐1,3‐dione‐pyrazolidinones in generally good to high yields with excellent diastereoselectivity under mild conditions.On an upward spiro: An efficient cycloaddition between 2‐arylidene‐1,3‐indandiones and an azomethine imine has been developed for the construction of dinitrogen‐fused spirocyclic heterocycles.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137534/1/ajoc201500529.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137534/2/ajoc201500529-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137534/3/ajoc201500529_am.pd

Quantitative characterization and analysis of pore-fractures in tar-rich coal under high-temperature pyrolysis based on micro-CT imaging

This study investigates pore distribution and permeability behavior of tar-rich coal following high-temperature pyrolysis at 500°C using X-ray computed tomography (CT) scanning. Coal samples post-pyrolysis were CT scanned, generating 1755 cross-sectional slices for three-dimensional reconstruction. An axial algorithm extracted pore distribution features, and geometric parameters were computed. An Equivalent Pore Network Model analyzed permeability characteristics. The results show that Post-pyrolysis pore distribution in tar-rich coal exhibited nonuniformity with a significant range in pore size distribution. Pores displayed concentrated spatial patterns. Total porosity was 14.24%, with 12.34% being connected. Most pores in Representative Elementary Volume (REV) regions fell within 10–50 μm in width and 20–60 μm in length, constituting over 40% of the total. Pore surface area peaked between 200–100 μm2, also comprising over 40% of the total. The Pore Network Model showed distinct characteristics in two REV regions: REV-1 demonstrated an early stage of development with poor connectivity, while REV-2 displayed a well-developed network with a bimodal coordination number histogram. The study highlights nonuniform post-pyrolysis pore distribution and significant pore size variations in tar-rich coal. This study is crucial for understanding permeability behavior in tar-rich coal after high-temperature pyrolysis

Gender Differences in Transnational Brand Purchase Decision Toward Mixed Culture and Original Culture Advertisements: An fNIRS Study

Culture strategy is very important for transnational brand marketing. Functional near-infrared spectroscopy (fNIRS) is a promising brain imaging modality for neuromarketing research. In the present study, we used fNIRS to explore the neural correlates of consumers’ purchase decision on different cross-culture marketing strategies. Forty Chinese participants watched transnational brands and products advertised with photographs of the brands’ original culture (the original culture advertisements) and advertised with photographs of Chinese culture (the mixed culture advertisements), respectively. The behavioral results showed that the female participants showed significantly higher purchase rate when watching the original culture advertisements than the mixed culture advertisements, whereas the male participants did not show significant preference between these two types. The fNIRS results further revealed that for the female participants, watching mixed culture advertisements evoked significant positive activation in the left dorsolateral prefrontal cortex and negative activation in the medial prefrontal cortex, which was not found in the male participants. These findings suggest possible cognitive and emotional differences between men and women in purchase decision making toward different cross-culture marketing strategy. The present study also demonstrates the great potential of fNIRS in neuromarketing research

Dissociated deficits of anticipated and experienced regret in at-risk suicidal individuals

Backgrounds: Decision-making deficits have been reported as trans-diagnostic characteristics of vulnerability to suicidal behaviors, independent of co-existing psychiatric disorders. Individuals with suicidal behaviors often regret their decision to attempt suicide and may have impairments in future-oriented processing. However, it is not clear how people with suicidal dispositions use future-oriented cognition and past experience of regret to guide decision-making. Here, we examined the processes of regret anticipation and experience in subclinical youth with and without suicidal ideation during value-based decision-making. Methods: In total, 80 young adults with suicidal ideation and 79 healthy controls completed a computational counterfactual thinking task and self-reported measures of suicidal behaviors, depression, anxiety, impulsivity, rumination, hopelessness, and childhood maltreatment. Results: Individuals with suicidal ideation showed a reduced ability to anticipate regret compared to healthy controls. Specifically, suicidal ideators’ experience of regret/relief was significantly different from that of healthy controls upon obtained outcomes, while their disappointment/pleasure experience was not significantly different from healthy controls. Conclusion: These findings suggest that young adults with suicidal ideation have difficulty predicting the consequences or the future value of their behavior. Individuals with suicidal ideation showed impairments in value comparison and flat affect to retrospective rewards, whereas individuals with high suicidality showed blunted affect to immediate rewards. Identifying the counterfactual decision-making characteristics of at-risk suicidal individuals may help to elucidate measurable markers of suicidal vulnerability and identify future intervention targets.</p