Bidentate Ferrocenyl-Dithiol Reagents for Nanocluster Surface Functionalization

Previous work using monodentate ferrocenyl-chalcogen reagents for nanocluster surface functionalization has indicated an effective way to involve ferrocene moieties onto the surface of these frameworks. However, the abilities of the large polynuclear nanocluster with ferrocene rich surface to form crystalline materials suitable for single crystal X-ray analysis proved to be limited. New bidentate ferrocenyl-chalcogen reagents have been synthesized and characterized in order to probe their ability in this case. The preparation of new bidentate ferrocenyl chalcogen reagents 1,1’-fc(C{O}OCH2CH2SH)2 (fc = ferrocenyl) and 1,1’-fc(C{O}NHCH2CH2SH)2 are presented. Furthermore, the preparation of silylated reagent fc(C{O}OCH2CH2SSiMe3)2 and silver thiolate polymer [fc(C{O}OCH2CH2SAg)2] are discussed. The formation of cluster [Ag74S19(dppp)6(fc(C{O}OCH2CH2S)2)18] using Ph2PCH2CH2CH2PPh2 (dppp) solubilized [fc(C{O}OCH2CH2SAg)2] and the sulfide reagent S(SiMe3)2 as precursors is also described. A single crystal X-ray analysis of [Ag74S19(dppp)6(fc(C{O}OCH2CH2S)2)18] enables a complete description of the molecule, including the arrangement of the ferrocenyl units on the surface. Cyclic voltammetry and UV-Vis absorption spectroscopy experiments were conducted on the synthesized ligands, complex and clusters, and the results of these experiments are presented

Model Selection for Gaussian Mixture Models for Uncertainty Qualification

Clustering is task of assigning the objects into different groups so that the objects are more similar to each other than in other groups. Gaussian Mixture model with Expectation Maximization method is the one of the most general ways to do clustering on large data set. However, this method needs the number of Gaussian mode as input(a cluster) so it could approximate the original data set. Developing a method to automatically determine the number of single distribution model will help to apply this method to more larger context. In the original algorithm, there is a variable represent the weight of each cluster. The weight means how the cluster will affect the data set, more precisely, each data point. So the idea is, we first set the number of the clusters to be a big number, then we are going to apply a penalized likelihood method to update the weights, while we are updating other parameters. The cluster will be deleted if its weight is less than a certain number we set. After all the iteration, the number of clusters will be generated, as well as other parameters of Gaussian model. The results from the simulation(MATLAB) shows that the number of the clusters could be generated from the modified method, and the final result of the clustering perform well to demonstrate the original data set. Although the modified algorithm could be used automatically do the whole clustering process, it need further investigation about its accuracy and improve its speed

Build-Operate-Transfer: A Concrete Study of Public-Private Partnerships

This dissertation focuses on one of the most used Public-Private Partnership (PPP) contracts: Build-Operate-Transfer (BOT) contract to study the theoretical problems haven’t been well addressed in the contract design. Chapter one focuses on the applicability of a general recognized method in PPP contract design. The conventional goal of contract design is to find the best possible arrangement between a principal and an agent from the principal's point of view. While this goal readily permits the principal to modify her options of an instrument, it treats her decision path as a black box. For principals who make decisions based on complementary collaborations among departments, proper institutional arrangements to assist better decision-making are of special importance. Departmental collaborations may create challenges for the proper application of otherwise sound approaches to find the optimal contract, such as, the Revelation Principle, which requires the agents' truthful and comprehensive reporting of their private information. While presuming that the principal has control over the entire mediation plan, this study finds that, in certain situations, cooperative principals with restricted power over the entire mediation plan should be cautious about making decisions relying only on the relevant information and the optimality of the coordinated results. It also shows that the full report of the agents' private information is key to a valid application of the revelation principle, regardless of the report's decision-relevance. Even with a full report, an entire mediation plan made by coordinated principals with restricted control may not achieve the best outcome, because they treat each other's decisions, while complementary, as sunk. Chapter One ends with regulatory suggestions concerning institutional design in institutions with multi-level cooperation. Chapter 2 uses BOT contract to study how the government efficiently resorts to the private sector firm's assistance for public goods' provision. BOT contract stipulation is a two-dimensional screening process for both the constructional and operational regulatory decisions. The optimal BOT contract extracts the private contractor's relative operational efficiency to compensate his upfront construction cost investment. Different from the literature, if the contractor only has one-dimensional high efficiency, "no distortion at top" for neither complementary decision is guaranteed. The prior distribution over types guides the decision of rationing out the least efficient type to reduce rent paying. A newly proposed Lagrangian decomposition method in combinatorial optimization studies is used to justify the optimal screening process. The government's utility is non-separable over the construction and operation decisions, hence the sovereign decision process potentially incurs a tradeoff between decisions independence and decision efficiency. Chapter 3 studies the liability allocation between partners when a negative shock hits in a Public-Private Partnership. In a PPP contract, a private sector firm trades its upfront investment and cost for a time-constrained de facto monopoly of the public good; while the government trades off the regulation intensity on the monopoly power for the gain of the public service provision. Given the presence of dual tradeoffs, the liability concern in a Public-Private Partnership and that in traditional partnerships differ. First, the government makes no initial investment but has the final ownership of the project. Such ownership empowers the government the rights to claim the residual value of the public project as a creditor. Second, when a negative shock hits, the private sector’s financial ability and its advantage on construction technology of the project provision prevents the private contractor from taking the full responsibility. This paper focuses on how to design PPP contracts that incentivize a high quality provision of the public good, concerning the randomness of the project’s revenue stream and the liability allocations when an unfavorable event happens. Unlike in a traditional partnership, the loss of the private sector in a PPP is not up to the limit of the investment they put in the public project but up to the limit of the gain they get from the public project’s revenue.Doctor of Philosoph

Investigation of wave propagation in piezoelectric helical waveguides with the spectral finite element method

The dispersion behaviors of wave propagation in waveguides of piezoelectric helical structures are investigated. By using the tensor analysis in the helical curve coordinate, the general strain − displacement relationship of piezoelectric helix is firstly considered. This paper's formulation is based on the spectral finite element which just requires the discretization of the cross-section with high-order spectral elements. The eigenvalue matrix of the dispersion relationship between wavenumbers and frequencies is obtained. Numerical examples on PZT5A and Ba2NaNb5O15 helical waveguides of a wide range of lay angles are presented. The effects of the piezoelectric on the dispersive properties and the variation tendency of dispersion curves on helix angles are shown. The mechanism of mode separation in piezoelectric helical waveguides is further analyzed through studying waves structures of the flexural modes

A Survey and Study on the Current Status of Mathematics Study Habits of Rural Junior High School Students in China

The research is supported by the research project of higher education reform in Jiangsu Province. Nos. 2019JSJG257, 2017JSJG212, Special research project on Rural Education in Yancheng City. No. XCZX21090, and Yancheng educational science planning project in 2021. No. 2021-L-136. (Sponsoring information) Abstract Based on the relevant theories, the article adopts literature research, questionnaire survey, and interview records to first analyze and summarize the research related to " mathematics study habits" and to define and classify the concepts related to "mathematics study habits." Take rural junior high school students in a school in China as the target group, and analyze the current situation of mathematics study habits of rural junior high school students in this school through a questionnaire survey based on the results. Furthermore, through personal interviews with rural junior high school students, teachers, and parents in the region, we completed the analysis of the factors that contribute to the formation of good mathematics study habits in rural junior high school students from the perspectives of students, teachers, and parents. Finally, combined with the current situation and influencing factors of mathematics learning habits of rural junior high school students in the region, corresponding countermeasures are proposed for the cultivation of good mathematical learning habits from the three perspectives of students, teachers and parents. Keywords: Rural junior high school students, Mathematics study habits, Influence factors, Habit development measures DOI: 10.7176/JEP/13-29-04 Publication date:October 31st 202