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Department of Mehcanical EngineeringSilver nanowires (AgNWs) electrodes satisfy the conditions that transmittance is higher than 80% at a wavelength of 550 nm and surface resistance is less than 100 ?? / ???, which are required criteria for the application of transparent electrodes. In addition to this, AgNWs have high flexibility and electrical conductivity that are suitable for flexible organic light-emitting diodes (OLEDs), and thus has been of a great interest as an alternative transparent electrode being able to replace indium tin oxide (ITO) of conventional displays. So far, for the development of alternative transparent electrodes, only transparency and sheet resistance criteria have been considered. However, when we consider flexible display devices in the near future, the transparent electrodes should be robust to folding and stretching in which conventional ITOs have intrinsic limitations. Therefore, a mechanical investigation on the structural stability during folding process is required for the application of AgNWs electrodes to flexible display devices. In this thesis, we performed the stress analysis for OLEDs that contain AgNWs or ITO electrode thin layer as one of components of flexible OLEDs displays. We compared the stress distributions of OLEDs under bending test and investigated the effect of the volume fraction of AgNWs on the structural robustness of the structures. The first reference model consisted of five layers including ITO with a thickness of 200 nm. Other four layers were aluminum (Al, 70nm), super yellow light-emitting polymer (PDY-132, 80nm), poly (3,4ethylenedioxythiophene) doped with poly (styrene sulfonate) (PEDOT:PSS, 40nm), and polyethylene terephthalate (PET, 0.1mm) layers. The second reference model also consisted of five layers, but now the ITO layer was replaced by AgNWs composite with PEOT:PSS with a thickness of 72 nm while the materials of the other four layers are the same. AgNWs of which length and diameter are 25+-5 um and 36 +-5 nm are employed in real production. Second reference model has a sheet resistance of 12.63 ?? / ??? and a transmittance of 93% at a wavelength of 550 nm. The real size of the flexible OLED device is 15 mm x 15 mm in the lateral directions, but we carefully reduced it to 7 mm x 1 mm without any significant change in the stress analysis to lower computational cost. We modelled the AgNWs composite layer as a conventional fiber-reinforced composite in which the AgNW acts as a fiber and the conductive polymer PEDOT: PSS acts as a resin. Then we determine the longitudinal Young???s modulus (E_L), transverse Young???s modulus (E_T), in-plane shear modulus (G_LT), and major Poisson???s ratio through a proper homogenization. Although AgNWs are arbitrary distributed in the real AgNWs composite layers, we assumed that they are distributed in orthogonal patterns in our numerical models. AgNWs manufacturing process uses spin-coating. Accurate volume fraction of AgNWs is unknown because the spin rate and time can be changed according to situation or purpose of experiment. However, I can assume that the volume fraction of AgNWs is 10% and the thickness of this layer is twice diameter of AgNW through the SEM images of AgNWs. The Young???s modulus and Poisson???s ratio of AgNW are 176 GPa, and 0.225. The Young???s modulus and Poisson???s ratio of PEDOT:PSS are 1.9 GPa and 0.34. For the homogenization for the AgNWs with 10% volume fraction, the values of E_L,E_T,G_LT and major Poisson???s ratio are 10.81 GPa, 10.87 GPa, 0.85 GPa, and 0.127. As the volume fraction increases from 6% to 65%, the longitudinal Young???s modulus also steeply increases from 7.19 GPa to 95.29 GPa. From the numerical analysis of OLEDs containing ITO or AgNWs with 10% volume fraction, Von-mises distributions in the other four layers such as Al, PDY-132, PEDOT: PSS, and PET layers in the both models were almost the same. However, the maximum Von-mises in the ITO layer, 6.99 GPa was found to be approximately 6.32 GPa larger than the maximum Von-mises in the AgNWs composite layer, 0.67 GPa. In addition to stress distribution, the fracture toughness of ITO and silver are about 2.59 MPa m^(1/2) and 40 MPa m^(1/2) at room temperature. Fracture toughness is used as a failure criterion of material and represents the resistance of the material to brittle fracture. If ITO is used for flexible OLEDs, it will be easy to break even under small deformation. As a result, it was confirmed that the AgNWs electrode is superior to the ITO electrode in the aspect of structural and flexural robustness during bending.ope

Save the Children Community Health Worker Program – Adverse Childhood Events Prevention

Background: Adverse childhood experiences (ACEs) are potentially traumatic events that occur between the ages of 0 to 17 in which are directly associated, in a dose–response manner, to many of the most common and serious health problems in the United States. Local Problem: 62% of California residents have experienced at least one ACE, and 16% have experienced at least four ACEs. ACEs are linked to nine of the ten leading causes of death in the United States Adults with four or more ACEs are 37.5 times more likely to attempt suicide, 3.2 times more likely to have chronic lower respiratory disease, 2.3 times more likely to have a stroke, cancer, or heart disease and 1.4 times more likely to have diabetes. ACEs are preventable. Methods: This project is in collaboration with Save the Children, an international nonprofit nongovernmental organization with the mission of addressing children’s physical and mental health needs. In order to address this public health problem, community health workers (CHWs), alongside health care professionals, are utilized to prevent and address ACEs. Interventions: The intervention was to research, design, and teach an ACEs prevention curriculum for the CHWs from Save the Children. The curriculum was instructed through synchronous Zoom didactic courses and constructed using Canvas for Teachers platform during Fall 2022 semester. The effectiveness of each class or module was measured by pre-tests and post-tests. Results: The aim of this project was to increase CHWs\u27 knowledge base by 25% or more on ACEs and prevention. The average increase in scores for the entire course was 32.40% which was statistically significant (p = .00295). Aim of the project was met. Conclusions: With adequate education and training, CHWs may effectively lower the prevalence and/or harmful effects of ACEs

Improved structural stability of Ni-rich cathode materials via simple dry process for Li-ion Batteries

Department of Energy Engineering (Battery Science and Technology)I reported that highly stable LiNi0.8Co0.1Mn0.1O2 (that is, NCM) via a simple and one-step dry surface treatment approach (that is, G-NCM). The cobalt precursor was coated on the surface of the bare NCM in purpose to improve the material integrity by protecting the cathode surface against the acidic species attack. Furthermore, the transition metal (TM) concentration gradient in the primary particles ensured the structural stability by suppressing the evolution of micro-crack in the cathode particles and reducing transition metal dissolution. The more important thing was the enhanced material integrity allowed stable and uniform solid electrolyte interphase (SEI) layer on the graphite anode, leading to unprecedented full-cell performance. After the surface treatment, the high temperature (45 oC) cycle performance was improved from 20 % for bare NCM to 50 % for G-NCM. During the cycle, the G-NCM retained higher average coulombic efficiency of ~99.8 % than that of the bare NCM (~98.5 %). The electrochemical performance was prepared by full-cell. This finding could be a breakthrough for the LIB technology, providing a rational approach for the development of advanced cathode materials.ope

Carbon nanotube-enhanced membrane for advanced water treatment

This study aims to develop the carbon nanotube composite membrane for the purpose of enhancing low pressure driven membrane process that encounters several challenging issues such as limited rejection efficiency and fouling. First, we synthesized multiwall carbon nanotubes/polyaniline(MWCNTs/PANI) complex by in-situ polymerization. The MWCNTs/PANI membrane removed natural organic matter 4 fold (80 %) which cannot be effectively removed by low-pressure driven membranes, as well as delivering 30 times higher water product (1400 LMH/bar) than the PES membrane. Further research on physical/chemical properties of the membrane revealed that the hydroxyl functionalized MWCNTs/PANI complex increased the hydrophilicity, porosity and slip length of the membrane by improving the membrane structure. It also altered the surface charge of the membrane, which contributed to the increase in electrostatic interaction between the membrane surface and the negatively charged organic matter, compared that currently used polymeric membranes are negatively charged. A second part of the research targeted to the application for enhanced organic matter removal in seawater pre-treatment. By enhanced natural organic matter removal and delivering high permeate flux, the MWCNTs membrane contributed to minimizing sludge volume generated from seawater desalination plant by reducing PAC dosage (1.5 g/L to 0.5 g/L). Lastly, protein fouling behavior in the MWCNTs membrane was examined under different solution chemistry (pH and ionic strength) for the wide application of MWCNTs membrane in wastewater reclamation and recovery of bioprocess industry. For the MWCNTs membrane, two dominant fouling mechanisms – complete/intermediate blocking and cake filtration operated under different pH and increasing ionic strength. Consequently, protein fouling of the MWCNTs membrane was found to be alleviated by controlling electrostatic interaction with charged proteins via pH and ionic strength

Political Activities of Foreign Multinational Corporations in the United States

The aim of this dissertation is to understand the political interests and activities of foreign multinational corporations (MNCs)in the United States. Foreign firms have strong incentives to influence US policies, as these policies heavily impact the firms’ existing or potential sales and investment. While certain US laws restrict foreign participation in political activities, domestically incorporated foreign firms have equal standing with American firms under US federal election and lobbying laws. Therefore, I argue that foreign firms may create new subsidiaries in the US or utilize existing subsidiaries as their domestic political agents, as a way to access and influence US policymakers. I call this phenomenon ‘political foreign investment.’ In the following chapters, I provide evidence in support of this theory. For instance, in “Foreign Direct Investment in Political Influence,” I demonstrate that majority foreign-owned subsidiaries, relative to American firms, are more likely to sponsor Political Action Committees and give a greater amount of campaign contributions to federal candidates. In “Foreign Lobbying through Domestic Subsidiaries,” I similarly find that majority foreign-owned firms tend to lobby more often and spend more on lobbying than American firms. The positive association between foreign ownership and political activity in the two papers holds after controlling for firm size, industry, state, and the extent of global integration. Moreover, I demonstrate that features of the foreign parent MNCs explain the outsized political activities of the domestic subsidiaries. Finally, in “Political FDI through Cross-border M&A” I conduct within-firm panel analyses showing that foreign acquisition of domestic firms increase their PAC and lobbying activities. Collectively, this dissertation highlights the political role of foreign direct investment, and sheds light on an understudied mechanism of foreign influence in the US. Also, the disproportionate political activities of the domestic subsidiaries raise normative questions on whether loopholes in US laws are circumvented by foreign interests.PHDPublic Policy & Political ScienceUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/162954/1/leejieun_1.pd

Individual Differences in Non-Native Phonological Contrast Learning: The Role of Perceptual Sensitivity to Sub-Phonemic Variation in Native Categories

The current study explored individual differences in sensitivity to sub-phonemic variation of acoustic cues in the perception of a native language (L1) category in order to test the hypothesis that second language (L2) learners’ different sensitivity to the L2-relevant acoustic dimension in L1 perception could explain individual variability in nonnative phonological contrast learning. In addition, this study also investigated whether the modified High Variability Phonetic Training (HVPT) paradigm could aid in nonnative phonological contrast learning. The cue-attention switching training was added to the typical HVPT paradigm with multiple talkers, expecting to reallocate learners’ attention away from the less relevant acoustic dimension to the more informative acoustic dimension in the perception of the target nonnative contrast(s). The present study targeted two groups of learners with different L1 backgrounds: naïve adult English learners of Korean and intermediate adult Korean learners of English. The multiple HVPT sessions trained English learners of Korean on a Korean three-way laryngeal contrast in stop (/p’/-/p/-/ph/) and trained Korean learners of English on three English vowel contrasts, /i/-/ɪ/, /ɛ/-/æ/, and /ʊ/ -/u/.The Visual Analogue Scaling (VAS) task measured English adult listeners’ sensitivity to sub-phonemic acoustic details in the perception of English stop voicing contrast with a stimuli continuum of English voiced and voiceless stops (/b/-/p/) varying in VOT and f0 at vowel onset. For Korean adult listeners, the AXB oddity task quantified learners’ sensitivity to within-category differences induced by spectral and duration cue changes, using a set of stimuli belonging to the Korean /i/ vowel but with different spectral and duration properties. The results of the HVPT training in experiments 1 and 3 revealed that in both groups, L2 learners with higher sensitivity to L2-relevant acoustic cues in L1 perception had an initial advantage in L2 contrast learning and showed more nativelike cue utilization during and after the HVPT. On the other hand, learners with less sensitivity to the “right” acoustic cues failed to systematically use those cues in perceiving the target L2 contrast(s). Learners who received the modified HVPT with the cue-attention switching training with L1 stimuli in experiments 2 and 4 demonstrated more native-like use of acoustic cues in L2 perception than learners who received only the typical HVPT with multiple talkers. English learners of Korean with relatively less sensitivity to f0 cues in the perception of English voicing contrast performed similarly to those with relatively high sensitivity to f0 cues. For Korean learners of English, the benefit of the cue-attention switching training was observed in learning the English /i/-/ɪ/ contrast, but not in more challenging /ɛ/-/æ/ and /ʊ/ -/u/ contrasts. Korean learners of English with the cue-attention switching training showed more reliance on spectral than duration cues like English native listeners. This study showed the relation between individual differences in sensitivity to sub-phonemic acoustic details in L1 and the nonnative novel phonological contrast learning and a possible type of training to overcome disadvantages due to the individual differences. The results suggest the transfer of L1 cue sensitivity to L2 cue utilization. That is, how successfully L2 learners progress to become more nativelike listeners can be predicted in terms of to what degree they have sensitivity to the L2 informative acoustic cue in L1 speech perception. This implies that individual differences in the L2-relevant cue sensitivity may determine the initial stage of learning and to what extent learners can benefit from L2 training. Moreover, this study emphasizes the importance of considering individual differences to predict L2 learners’ learning outcomes and provide appropriate L2 training to learners whose perceptual abilities may place them at a disadvantage. The VAS and AXB oddity tasks showed possibilities as pretraining assessments to predict the acquisition of L2 phonological contrasts and L2 cue-weighting strategies