Cu2Se-based thermoelectric cellular architectures for efficient and durable power generation

Thermoelectric power generation offers a promising way to recover waste heat. The geometrical design of thermoelectric legs in modules is important to ensure sustainable power generation but cannot be easily achieved by traditional fabrication processes. Herein, we propose the design of cellular thermoelectric architectures for efficient and durable power generation, realized by the extrusion-based 3D printing process of Cu2Se thermoelectric materials. We design the optimum aspect ratio of a cuboid thermoelectric leg to maximize the power output and extend this design to the mechanically stiff cellular architectures of hollow hexagonal column- and honeycomb-based thermoelectric legs. Moreover, we develop organic binder-free Cu2Se-based 3D-printing inks with desirable viscoelasticity, tailored with an additive of inorganic Se-8(2-) polyanion, fabricating the designed topologies. The computational simulation and experimental measurement demonstrate the superior power output and mechanical stiffness of the proposed cellular thermoelectric architectures to other designs, unveiling the importance of topological designs of thermoelectric legs toward higher power and longer durability

Examining the generalizability of research findings from archival data

This initiative examined systematically the extent to which a large set of archival research findings generalizes across contexts. We repeated the key analyses for 29 original strategic management effects in the same context (direct reproduction) as well as in 52 novel time periods and geographies; 45% of the reproductions returned results matching the original reports together with 55% of tests in different spans of years and 40% of tests in novel geographies. Some original findings were associated with multiple new tests. Reproducibility was the best predictor of generalizability—for the findings that proved directly reproducible, 84% emerged in other available time periods and 57% emerged in other geographies. Overall, only limited empirical evidence emerged for context sensitivity. In a forecasting survey, independent scientists were able to anticipate which effects would find support in tests in new samples

The Effect of Categorization on Investment Decisions: Three Essays in the Fintech Industry

Market actors, such as venture founders, incumbent managers, and third parties, respectively shape categories to influence investors’ perceptions of the nascent markets and related firms. Yet we know less about the idiosyncratic role that producers and third parties play in the investment process. This dissertation seeks to advance our understanding about categorizations in shaping investment decisions. The first essay of the dissertation distinguishes between categorical associations made by external third parties (hearafter, “external categorization”) and those made internally by organizational insiders (hearafter, “internal categorization”) and accounts for their respective effects on investment decisions. Based on a database on blockchain ventures, I show that ventures obtain more funding when external experts deem them categorically focused despite co-founders’ claims that the venture is moderately unfocused. The insight is that the effect of straddling can be negative or positive depending on who the categorizer is. The second essay reinforces the earlier findings by meta-analyzing prior 150 publications. I illustrate the overall and unique relationships among multiple categorical associations made by external third parties (hereafter, external straddling ), those made by organizational insiders (hearafter, “internal straddling”), and several organizational outcomes. I find that external straddling negatively drives audience appeal while internal straddling positively drives audience appeal, and that these effects are robust after considering different types of outcomes and confounding moderators. I present a more nuanced take on the role of straddling, thus raising the need for reconceptualizing the notion of category straddling. The third essay introduces two new properties of categorization that help predict CVC investment decisions of incumbent managers: First, the categorization breadth by top managers—tendency to define peer firms beyond a firm’s existing industry boundaries—leads them to scan the periphery of the environment and increase the firm’s proclivity for CVC investment. Second, the categorization granularity by top managers—tendency to distinguish specific subcategories of peer firms rather than identify coarse groupings of peers—leads to more caution and decreases the firm’s proclivity for CVC investment. My analyses of US banks’ CVC investment in FinTech ventures provide support to the dual roles managerial categorizations play during the CVC investment process

Analysis of Laser Cutting Process for Different Diagonal Material Shapes

In this study, the laser cutting characteristics were analyzed according to the shape of the back side of the specimen, and the laser cutting characteristics were compared according to the thickness of the edge (10 mm, 20 mm, and 30 mm). A Yb-YAG laser was used in this study, and the cutting target was STS304 with a thickness of 50 mm, and the cutting process was analyzed using a high-speed camera. In the experiment, it was found through image analysis that the cutting performance was excellent at 30 mm thickness of the edge. In order to analyze this reason, a thermal conduction analysis (numerical simulation) was performed, and it was confirmed that the thicker thickness of the edge caused a preheating effect during laser cutting due to a large amount of heat accumulation. This effect can be used as a reference for the initial processing state while cutting thick metals as it is a characteristic that has not been revealed before

Intracranial Pressure Patterns and Neurological Outcomes in Out-of-Hospital Cardiac Arrest Survivors after Targeted Temperature Management: A Retrospective Observational Study

We aimed to investigate intracranial pressure (ICP) changes over time and the neurologic prognosis for out-of-hospital cardiac arrest (OHCA) survivors who received targeted temperature management (TTM). ICP was measured immediately after return of spontaneous circulation (ROSC) (day 1), then at 24 h (day 2), 48 h (day 3), and 72 h (day 4), through connecting a lumbar drain catheter to a manometer or a LiquoGuard machine. Neurological outcomes were determined at 3 months after ROSC, and a poor neurological outcome was defined as Cerebral Performance Category 3–5. Of the 91 patients in this study (males, n = 67, 74%), 51 (56%) had poor neurological outcomes. ICP was significantly higher in the poor outcome group at each time point except day 4. ICP elevation was highest between days 2 and 3 in the good outcome group, and between days 1 and 2 in the poor outcome group. However, there was no difference in total ICP elevation between the poor and good outcome groups (3.0 vs. 3.1; p = 0.476). All OHCA survivors who had received TTM had elevated ICP, regardless of neurologic prognosis. However, the changing pattern of ICP levels differed depending on the neurological outcome

Direct ink writing of three-dimensional thermoelectric microarchitectures

Microscale three-dimensional thermoelectric architectures can be fabricated through the direct writing of particle-based thermoelectric inks and used to create microthermoelectric generators that exhibit a power density of 479.0 mu W cm(-2). Microthermoelectric modules can be used as energy harvesters, active coolers and thermal sensors in integrated systems. However, manufacturing such modules with traditional microfabrication processes is costly and produces only two-dimensional thermoelectric films, which limit the formation of high-temperature gradients and thus the amount of power generated. Here we show that microscale three-dimensional thermoelectric architectures can be fabricated through the direct writing of particle-based thermoelectric inks. Using size control and surface oxidation, the characteristics of (Bi,Sb)(2)(Te,Se)(3)-based particle inks are engineered to create colloidal inks with high viscoelasticity and without organic binders, and the inks are directly written into complex architectures using a 3D printing process. The resulting structures exhibit high thermoelectric figures of merit of 1.0 (p type) and 0.5 (n type), which are comparable to those of bulk ingots. Microthermoelectric generators made from three-dimensionally written vertical filaments exhibit large temperature gradients and a power density of 479.0 mu W cm(-2)

Doping-induced viscoelasticity in PbTe thermoelectric inks for 3D printing of power-generating tubes

Thermoelectric (TE) technologies offer promising means to enhance fossil energy efficiencies by generating electricity from waste heat from industrial or automobile exhaust gases. For these applications, thermoelectric modules should be designed from the perspective of system integration for efficient heat transfer, system simplification, and low processing cost. However, typical thermoelectric modules manufactured by traditional processes do not fulfil such requirements, especially for exhaust pipes. Hence, a 3D-printing method for PbTe thermoelectric materials is reported to design high-performance power-generating TE tubes. The electronic doping-induced surface charges in PbTe particles are shown to significantly improve the viscoelasticities of inks without additives, thereby enabling precise shape and dimension engineering of 3D bulk PbTe with figures of merit of 1.4 for p-type and 1.2 for n-type materials. The performance of the power-generating TE tube fabricated from 3D-printed PbTe tubes is demonstrated experimentally and computationally as an effective strategy to design system-adaptive high-performance thermoelectric generators