Design and Synthesis of Polymer-Based Advanced Nanomaterials Using Raft Polymerization and Click Reaction

This research focuses on exploring new synthetic approaches to prepare polymer-based advanced nanomaterials using highly efficient chemical tools, such as reversible addition-fragmentation chain transfer (RAFT) polymerization and click reactions. In the first project, novel synthetic routes to produce fullerene-based polymers were designed. First, mono-alkynyl functionalized fullerene was prepared starting with pristine fullerene (C60). Methyl methacrylate and 6-azido hexyl methacrylate were then randomly copolymerized via RAFT polymerization with well-controlled molecular weights and copolymer compositions. Finally, the two moieties were covalently assembled into a series of well-defined side-chain fullerene polymers (SFP\u27s) via the copper-catalyzed click reaction. The TGA and UV-vis analyses demonstrated consistent and high conversions for most of the samples. Furthermore, the SEM images of these polymers showed the formation of various supramolecular nanoparticle assemblies and crystalline-like clusters depending on the fullerene contents and polymer chain lengths. Additionally, tadpole-like fullerene polymers (TFP) were generated from bi-alkynyl functionalized fullerene, followed by a click reaction to anchor azido-capped polymers as tails . The resultant polymers behaved as surfactants to significantly improve the solubility of graphene. The UV-vis and FT-IR spectra indicated the strong π-π stacking interactions between the TFP\u27s and graphene. TEM images also displayed different dispersions of the complexes of TFP\u27s and graphene in various solvents. Another aspect of this Ph.D. research was the fabrication of Janus nanoparticles (NP\u27s). A critical challenge in NP functionalization has been the preparation of polymer-grafted asymmetric (Janus) NP\u27s (dia. \u3c100 \u3enm). After multiple trials using different protection-deprotection methods and face-blocking moieties, such as wax beads and planar silica wafers, we designed a robust and cyclic method to synthesize such NP\u27s involving a reversible click reaction and a grafting to strategy. A novel mechanochemical approach was introduced into the particle interactions to selectively achieve the protection-deprotection of NP\u27s, which was combined with polymer modification of the unprotected surfaces of the NP\u27s via a grafting to approach. The azide-functionalized larger particles could be recycled as face-blocking moieties. Using this pathway, we prepared 15 nm silica NP\u27s that were partially functionalized with poly(methyl methacrylate). Additionally, the unique self-assembly behaviors of the resultant Janus NP\u27s and their interactions with isotropic NP\u27s were investigated in different solvents and concentrations by TEM and AFM analyses. The dispersion of NP\u27s in polymer matrices is a critical factor in determining the properties of the resulting nanocomposites. In the last part, we studied on NP\u27s modification via surface-initiated RAFT polymerization using various functional monomers, and the dispersion of the NP\u27s in different polymer matrices. Kinetic studies were investigated for each polymerization to demonstrate the controlled nature of the polymerization on the surface of the NP\u27s. In addition to the homopolymers, multi-layers of block copolymer brushes were grafted on silica NP\u27s by sequential RAFT polymerizations. Moreover, pseudo gradient copolymer brushes were also prepared by inserting a third random copolymer block into the middle of the two homopolymer blocks, which was established as an easy and straightforward method to synthesize gradient brushes on NP\u27s

Simple HRIR Filter Achieved with the Data of KEMAR

The HRIR filters are widely used in many fields today, for example, some ASMR recordings and stereo songs mixing. My function provides a simple HRIR filter that could make a mono recording mixed into a stereo, binaural recording with relatively accurate positioning using the data of Knowles Electionics Mannequin for Acousitc Research (KEMAR).HRTF dataset is provided by CIPIC HRTF Database. Guided by William Martens

The Influence Factors and Promotion Strategies of Coal Enterprise Soft Power

Coal enterprise soft power is an important part of enterprise core competitiveness which is crucial in the development and construction business. According to development feature of coal business and the coal industry combined with the current form of development changes, on the basis of systematically analyzing the formation affecting factors of coal enterprise soft power, the writer thinks that coal enterprises should shape the corporate culture, continue to enhance the coal enterprise management innovation and technological innovation, focus on personnel training of coal enterprises, fully modify the image of coal enterprises to enhance the soft power, and take enterprise soft power building as hard power to expand and extend the platform to improve coal enterprise comprehensive strength and competitiveness

Pre-trained Neural Recommenders: A Transferable Zero-Shot Framework for Recommendation Systems

Modern neural collaborative filtering techniques are critical to the success of e-commerce, social media, and content-sharing platforms. However, despite technical advances -- for every new application domain, we need to train an NCF model from scratch. In contrast, pre-trained vision and language models are routinely applied to diverse applications directly (zero-shot) or with limited fine-tuning. Inspired by the impact of pre-trained models, we explore the possibility of pre-trained recommender models that support building recommender systems in new domains, with minimal or no retraining, without the use of any auxiliary user or item information. Zero-shot recommendation without auxiliary information is challenging because we cannot form associations between users and items across datasets when there are no overlapping users or items. Our fundamental insight is that the statistical characteristics of the user-item interaction matrix are universally available across different domains and datasets. Thus, we use the statistical characteristics of the user-item interaction matrix to identify dataset-independent representations for users and items. We show how to learn universal (i.e., supporting zero-shot adaptation without user or item auxiliary information) representations for nodes and edges from the bipartite user-item interaction graph. We learn representations by exploiting the statistical properties of the interaction data, including user and item marginals, and the size and density distributions of their clusters

The Research on Exogenous Problems of Farmers’ Piritual and Cultural Education in China

The author studied and analyzed the exogenous problems of the farmers’ spiritual and cultural education, and found out: In today’s China, the exogenous problems of the farmers’ spiritual and cultural education mainly reflected in the separation of spiritual and cultural education is from social environment, political system, economic development, and cultural concepts etc. Then the author put forward to the countermeasures and suggestions aimed at optimizing the allocation of famers’ spiritual and cultural educations resources, environment and evaluation system construction and so on

Preparation and imaging of intravascular high-frequency transducer

Intravascular ultrasound (IVUS) imaging is by far the most favorable imaging modality for coronary artery evaluation. IVUS transducer design and fabrication, a key technology for intravascular ultrasound imaging, has a significant impact on the performance of the imaging results. Herein, a 35-MHz side-looking IVUS transducer probe was developed. With a small aperture of 0.40 mm × 0.40 mm, the transducer exhibited a very wide -6 dB bandwidth of 85% and a very low insertion loss of -12 dB. Further, the in vitro IVUS imaging of a porcine coronary artery was performed to clearly display the vessel wall structure while the corresponding color-coded graph was constructed successfully to distinguish necrotic core and fibrous plaque via image processing. The results demonstrated that the imaging performance of the optimized design transducer performs favorably