FABRICATION OF HIGH FIDELITY, HIGH INDEX 3D PHOTONIC CRYSTALS USING A TEMPLATING APPROACH

In this dissertation, we demonstrate the fabrication of high fidelity 3D photonic crystal through polymer template fabrication, backfilling and template removal to obtain high index inversed inorganic photonic crystals (PCs). Along the line, we study the photoresist chemistry to minimize the shrinkage, backfilling strategies for complete infiltration, and template removal at high and low temperatures to minimize crack-formation. Using multibeam interference lithography (MBIL), we fabricate diamond-like photonic structures from commercially available photoresist, SU-8, epoxy functionalized polyhedral oligomeric silsesquioxane (POSS), and narrowly distributed poly(glycidyl methacrylate)s (PGMA). The 3D structure from PGMA shows the lowest shrinkage in the [111] direction, 18%, compared to those fabricated from the SU-8 (41%) and POSS (48%) materials under the same conditions. To fabricate a photonic crystal with large and complete photonic bandgap, it often requires backfilling of high index inorganic materials into a 3D polymer template. We have studied different backfilling methods to create three different types of high index, inorganic 3D photonic crystals. Using SU-8 structures as templates, we systematically study the electrodeposition technique to create inversed 3D titania crystals. We find that 3D SU-8 template is completely infiltrated with titania sol-gel through a two-stage process: a conformal coating of a thin layer of films occurs at the early electrodeposition stage (\u3c 60 min), followed by bottom-up deposition. After calcination at 500 oC to remove the polymer template, inversed 3D titania crystals are obtained. The optical properties of the 3D photonic crystals characterized at various processing steps matches with the simulated photonic bandgaps (PBGs) and the SEM observation, further supporting the complete filling by the wet chemistry. Since both PGMA and SU-8 decompose at a temperature above 400 oC, leading to the formation of defects and cracks, a highly thermal and mechanical stable template is desired for PC fabrication. We fabricate the 3D POSS structures by MBIL, which can be converted to crack-free silica-like templates over the entire sample area (~5 mm in diameter) by either thermal treatment in Ar at 500 oC or O2 plasma, and the porosity can be conveniently controlled by O2 plasma power and time. Since POSS derivatives are soluble in HF aqueous solutions, we successfully replicate the 3D porous structures into polymers, such as PGMA and poly(dimethyl siloxane) (PDMS). We note that all the fabrication processes are conducted at room temperature, including template fabrication, infiltration and removal. Further, using 3D POSS structures as templates, here, we demonstrate the synthesis of 3D photonic crystals from silicon carbide and boron carbide, respectively, which are thermally stable above 1100 oC in Ar. These non-oxide ceramic photonic crystals are potentially useful as ultrahigh temperature thermal barrier coatings that provide thermal protection for metallic components

Distortion of 3D SU8 Photonic Structures Fabricated by Four-beam Holographic Lithography with Umbrella Configuration

We present a quantitative study of the distortion from a three-term diamond-like structure fabricated in SU8 polymer by four-beam holographic lithography. In the study of the refraction effect, theory suggests that the lattice in SU8 should be elongated in the [111] direction but have no distortion in the (111) plane, and each triangular-like hole array in the (111) plane would rotate by ~30º away from that in air. Our experiments agree with the prediction on the periodicity in the (111) plane and the rotation due to refraction effect, however, we find that the film shrinkage during lithographic process has nearly compensated the predicted elongation in the [111] direction. In study of photonic bandgap (PBG) properties of silicon photonic crystals templated by the SU8 structure, we find that the distortion has decreased quality of PBG

The asymmetric effect of infectious disease equity market volatility for the physical education economy: implication for a post-Covid world

Due to the growing importance of the sports economy and the severe impact of the current Covid-19 pandemic on it, this paper examines the way in which the infectious disease stock market volatility (ID-EMV) tracker affects the Covid world sports economy from an asymmetrical perspective. We selected the newspaperbased ID-EMV index and Wind Physical Education Concept Index (PEC) for our research. First, the results of conventional causality tests showed that the tests ID-EMV and PEC were unable to detect causality, implying that stock market volatility stemming from COVID-19 risk had no impact on the sports economy. However, considering potential asymmetric effects in this relationship, we further investigated whether ID-EMV could significantly affect PEC under both positive and negative shocks. The empirical results confirm the existence of asymmetric effects. Therefore, we are the first to focus on this asymmetric effect and conduct empirical research, which may help provide educators and financial market participants with a novel research perspective

First mid-Neoproterozoic paleomagnetic results from the Tarim Basin (NW China) and their geodynamic implications

In order to improve the understanding of the configuration and breakup history of the Rodinia supercontinent, a paleomagnetic study has been carried out on the 807 ± 12 Ma Aksu dyke swarm (ADS) in Aksu area, northwestern Tarim Block (NW China). The magnetic mineralogical investigations show that the magnetic remanence is principally carried by automorphous titanium-poor magnetite. The measured samples from nine dykes present stable magnetic directions with both normal and reversed magnetic polarities. Because of the monoclinal bedding of overlying sedimentary rocks, no fold test can be provided. However, a positive reversal test is obtained. The magnetic site-mean direction in geographic coordinates is close to, but significantly different from, the present earth field (PEF). A tilt-corrected paleomagnetic pole, therefore, is computed: 19°N, 128°E, DP = 6°, DM = 7° with N = 9. This new paleomagnetic observation reveals that the Tarim Block was located at an intermediate latitude of 43 ± 6°N. Integrating the geochronological studies of dyke swarms from Australia and the Aksu area and referring to the configuration of the Rodinia supercontinent proposed by Moores [Geology 19 (1991) 425] and Li and Powell [Earth Sci. Rev. 53 (2001) 237], the Tarim Block was placed north of Australia with the Aksu dykes being a possible northward continuation of lamprophyre dykes and kimberlite pipes in the northeast part of the Kimberley Craton, Wester

Evaluation and Classification of Mobile Financial Services Sustainability Using Structural Equation Modeling and Multiple Criteria Decision-Making Methods

Despite the fast emergent of smartphones in day-to-day activity, the sustainable development of mobile financial services (MFS) remains low partially due to online consumer’s trust and perceived risk. This research broadens the trust and the perceived risk at the multi-dimensional for understanding and prioritizing alternatives of MFS decision. A combined methodology; structural equation modeling (SEM) with two multiple criteria decision-making (MCDM) methods such as a technique for order of preference by similarity to ideal solution (TOPSIS) and analytic hierarchy process (AHP) were applied for data analysis. The two steps SEM-TOPSIS techniques were adopted through a two-types survey on datasets consisting of 538 MFS users, and 74 both experienced MFS users and experts in Togo. The SEM is used for causal relationships and assigning weights for the TOPSIS input. TOPSIS was applied for providing MFS alternative classification, in which the results were compared with prior research using the SEM-AHP technique on the given population. The results via SEM revealed particularly strong support for the dispositional trust and perceived privacy risk. Trust has a negative relationship with perceived risk. Except for perceived time risk, all the antecedents of perceived risk and trust validated the proposed relationship. The findings of TOPSIS uncovered that mobile money transfer (MMT) remains the core application used, followed by mobile payment (MP) and mobile banking (MB) and, therefore, consistent with AHP. However, the TOPSIS technique is better suited to the problem of MFS selection for this study field. This research offers a novel and practical modeling and classification concept for researchers, companies’ managers, and experts in the areas of information technology. The implications, limitations, and future research are provided

Formation conditions of natural gas fields in the lacustrine basin in eastern China: Insights into the first discovery within the Bohai Bay Basin

The hydrocarbon source of Bohai Bay Basin is dominated by oil-prone kerogens of type II2-II1 within semi-deep and deep lacustrine facies. In the Neogene period, faults were well-developed via significant structural activity. The Bohai Sea is generally considered to have no geological basis for the formation of large natural gas fields. Through analogous analysis of domestic and international gas fields, the key geological factors that restrict formation in continental rift lacustrine basins were studied, including gas source, preservation conditions, and reservoirs. A natural gas enrichment and accumulation model within a petroliferous basin is presented. The model indicates that rapid subsidence and high-intensity gas generation within petroliferous sags during the late stages were main contributors to natural gas field formation. Archean metamorphic buried hill reservoirs and thick, overpressure mudstone with strong vertical sealing ability provided favorable storage space and preservation, respectively. Using the model, an integrated Archaean metamorphic buried hill condensate gas reservoir, Bozhong 19–6, was discovered in the Bohai Bay Basin. The natural gas reserves are about 450×109 m3, equivalent to oil production of 800 ×106 m3, and signify a breakthrough in natural gas exploration of continental rift lacustrine basins in China

A meta-analysis of the relationship between climate change experience and climate change perception

Will climate change experience shape people\u27s climate change perception? To examine the evidence, we performed a pre-registered meta-analysis using data from 302 studies, covering 351,378 observations. Our results find that climate change experience only has a weak positive correlation with climate change awareness in general (r = 0.098, 95% CI 0.0614, 0.1348), and the effect sizes vary considerably across different climate events. General hazard and temperature anomalies experiences have significant correlations, but other events exhibit no or neglectable effects. The moderator analysis showed that self-reported studies result in higher correlations, whereas studies based on victims\u27 actual experiences report lower effect sizes. Our study suggests that people\u27s climate change experiences may not be effective in shaping their awareness of climate change, which is likely due to people\u27s attribution style and adaptability. The importance of proactive education thus is further emphasized to raise the awareness of climate change