Matching Items (4)
Description
Diamond and cubic boron nitride (c-BN) are ultra wide band gap semiconductors (Eg>3.4 eV) and share similar properties in various aspects, including being isoelectronic, a 1% lattice mismatch, large band gap, high thermal conductivity. Particularly, the negative electron affinity (NEA) of diamond and c-BN is an unusual property that has led to effects such as p-type surface conductivity, low temperature thermionic emission, and photon enhanced thermionic emission. In this dissertation, the interface chemistry and electronic structure of dielectrics on diamond and c-BN are investigated with X-ray and ultraviolet photoemission spectroscopy (XPS and UPS). The first study established that the surface conductive states could be established for thin Al2O3 on diamond using a post deposition H-plasma process. At each step of the atomic layer deposition (ALD) and plasma processing, the band alignment was characterized by in situ photoemission and related to interface charges. An interface layer between the diamond and dielectric layer was proposed to explain the surface conductivity. The second study further investigated the improvement of the hole mobility of surface conductive diamond. A thin layer of Al2O3 was employed as an interfacial layer between surface conductive hydrogen-terminated (H-terminated) diamond and MoO3 to increase the distance between the hole accumulation layer in diamond and negatively charged states in acceptor layer. With an interfacial layer, the ionic scattering, which was considered to limit the hole mobility, was reduced. By combining two oxides (Al2O3 and MoO3), the hole mobility and concentration were modulated by altering the thickness of the Al2O3 interfacial layer. The third study focused on the electronic structure of vanadium-oxide-terminated c-BN surfaces. The vanadium-oxide-termination was formed on c-BN by combining vanadium deposition using molecular beam deposition (MBD) and oxygen plasma treatment. After thermal annealing, a thermally stable NEA was achieved on c-BN. A model was proposed based on the deduced interface charge distribution to explain the establishment of an NEA.
ContributorsYang, Yu (Author) / Nemanich, Robert J (Thesis advisor) / McCartney, Martha (Committee member) / Ponce, Fernando (Committee member) / Qing, Quan (Committee member) / Arizona State University (Publisher)
Created2018
Description现今的理论研究及实践表明，供应链上各个企业进行协调运作的基础是节点企业间有效信息进行高效传递。但供应链上下游企业在合作过程中通常存在信息不完全对称现象、牛鞭效应等问题，供应链中信息传递的实时性及真实性受到较大影响，这也是导致供应链管理整体效率不高的原因之一。因此，供应链伙伴间信息共享问题已是国内外学者普遍关注的焦点。本文旨在针对目前我国家居供应链企业间信息沟通不畅、信息共享不充分的问题及其理论研究的不足，来开展针对影响家居供应链企业间信息共享因素的实证研究。本文基于家居供应链这一特殊的行业供应链，建立基于家居供应链企业间信息共享关键影响因素理论模型，通过实证方法来寻找影响供应链企业间信息共享的关键因素及其具体影响程度。
在已有文献的基础上，本文提出信任、共同愿景、信息技术能力、渠道权力结构与信息共享间影响关系的概念模型，并对长三角及珠三角地区家居供应链经销商企业进行问卷调查研究。最后在回收的 164 份有效问卷基础上通过数据分析来验证假设。研究结果显示：(1)不论是家居工厂与经销商间还是家居卖场与经销商间，信任对共享信息的内容和质量都有显著正向影响。(2)家居工厂与经销商间的共同愿景对彼此间信息共享内容有显著正向影响作用，但对信息共享质量作用不明显。而家居卖场与经销商间的共同愿景对信息共享的内容和质量都有正向影响作用。(3)经销商的信息技术能力对双方间信息共享的内容和质量都有显著影响，同时，还能促进家居工厂与经销商之间的信任，间接影响双方的信息共享程度。(4) 家居卖场与经销商间的渠道权力对双方间的信任程度有显著影响，而对双方间的信息共享没有直接影响。
本研究主要研究贡献在于：发现影响家居供应链信息共享的关键因素，弥补了现有文献对中国供应链企业信息共享影响因素研究的不足，特别聚焦于家居供应链；从供应链上下游整体角度出发，探讨了中国情境下信任、共同愿景、信息技术能力和渠道权力结构与信息共享之间的作用机理。
在已有文献的基础上，本文提出信任、共同愿景、信息技术能力、渠道权力结构与信息共享间影响关系的概念模型，并对长三角及珠三角地区家居供应链经销商企业进行问卷调查研究。最后在回收的 164 份有效问卷基础上通过数据分析来验证假设。研究结果显示：(1)不论是家居工厂与经销商间还是家居卖场与经销商间，信任对共享信息的内容和质量都有显著正向影响。(2)家居工厂与经销商间的共同愿景对彼此间信息共享内容有显著正向影响作用，但对信息共享质量作用不明显。而家居卖场与经销商间的共同愿景对信息共享的内容和质量都有正向影响作用。(3)经销商的信息技术能力对双方间信息共享的内容和质量都有显著影响，同时，还能促进家居工厂与经销商之间的信任，间接影响双方的信息共享程度。(4) 家居卖场与经销商间的渠道权力对双方间的信任程度有显著影响，而对双方间的信息共享没有直接影响。
本研究主要研究贡献在于：发现影响家居供应链信息共享的关键因素，弥补了现有文献对中国供应链企业信息共享影响因素研究的不足，特别聚焦于家居供应链；从供应链上下游整体角度出发，探讨了中国情境下信任、共同愿景、信息技术能力和渠道权力结构与信息共享之间的作用机理。
ContributorsYang, Yu (Author) / Gu, Bin (Thesis advisor) / Chen, Xinlei (Thesis advisor) / Zheng, Zhiqiang (Committee member) / Arizona State University (Publisher)
Created2019
Description
Recent studies indicate the presence of nano-scale titanium dioxide (TiO[subscript 2]) as an additive in human foodstuffs, but a practical protocol to isolate and separate nano-fractions from soluble foodstuffs as a source of material remains elusive. As such, we developed a method for separating the nano and submicron fractions found in commercial-grade TiO[subscript 2] (E171) and E171 extracted from soluble foodstuffs and pharmaceutical products (e.g., chewing gum, pain reliever, and allergy medicine). Primary particle analysis of commercial-grade E171 indicated that 54% of particles were nano-sized (i.e., < 100 nm). Isolation and primary particle analysis of five consumer goods intended to be ingested revealed differences in the percent of nano-sized particles from 32%‒58%. Separation and enrichment of nano- and submicron-sized particles from commercial-grade E171 and E171 isolated from foodstuffs and pharmaceuticals was accomplished using rate-zonal centrifugation. Commercial-grade E171 was separated into nano- and submicron-enriched fractions consisting of a nano:submicron fraction of approximately 0.45:1 and 3.2:1, respectively. E171 extracted from gum had nano:submicron fractions of 1.4:1 and 0.19:1 for nano- and submicron-enriched, respectively. We show a difference in particle adhesion to the cell surface, which was found to be dependent on particle size and epithelial orientation. Finally, we provide evidence that E171 particles are not immediately cytotoxic to the Caco-2 human intestinal epithelium model. These data suggest that this separation method is appropriate for studies interested in isolating the nano-sized particle fraction taken directly from consumer products, in order to study separately the effects of nano and submicron particles.
ContributorsFaust, James (Author) / Doudrick, Kyle (Author) / Yang, Yu (Author) / Capco, David (Author) / Westerhoff, Paul (Author) / College of Liberal Arts and Sciences (Contributor) / Molecular and Cellular Biology (Contributor) / School of Life Sciences (Contributor) / Ira A. Fulton Schools of Engineering (Contributor) / School of Sustainable Engineering and the Built Environment (Contributor)
Created2016-10-31
Description
This study examined the effect of the amino acid composition of protein capsids on virus inactivation using ultraviolet (UV) irradiation and titanium dioxide photocatalysis, and physical removal via enhanced coagulation using ferric chloride. Although genomic damage is likely more extensive than protein damage for viruses treated using UV, proteins are still substantially degraded. All amino acids demonstrated significant correlations with UV susceptibility. The hydroxyl radicals produced during photocatalysis are considered nonspecific, but they likely cause greater overall damage to virus capsid proteins relative to the genome. Oxidizing chemicals, including hydroxyl radicals, preferentially degrade amino acids over nucleotides, and the amino acid tyrosine appears to strongly influence virus inactivation. Capsid composition did not correlate strongly to virus removal during physicochemical treatment, nor did virus size. Isoelectric point may play a role in virus removal, but additional factors are likely to contribute.
ContributorsMayer, Brooke K. (Author) / Yang, Yu (Author) / Gerrity, Daniel W. (Author) / Abbaszadegan, Morteza (Author) / Ira A. Fulton Schools of Engineering (Contributor)
Created2015-11-08