I. Stereochemical Control of Chiral Assembly and Liquid Crystal Phase Formation of Nonamphiphilic Molecules in Water II. Control Bacterial Quorum Sensing and Quorum Sensing-mediated Activities Using Small Unnatural Molecules

The primary goal of this research is to utilize organic synthesis as a tool to prepare small molecules that find potential application in different areas including colloidal and material science, biological chemistry, and medicinal chemistry. Chapter 1 describes the interpretation of the conformation of nonamphiphilic mesogen disodium cromoglycate (5´DSCG) when it exists as part of an assembly in water. The study of thermodynamic incompatibility and miscibility suggest that a previously proposed model for the assembly of 5´DSCG may be applicable to nonamphiphilic organic dyes and other mesogens. Chapter 2 presents a study of stereochemical control on assembly and liquid crystal formation by nonamphiphilic molecules. Three stereoisomers of a disodium chromonyl carboxylate derivative, 5´DSCG-diviol, were designed and synthesized. The chiral stereoisomers formed chiral nematic liquid crystals while the achiral counterpart did not form any kind of liquid crystals. The hydrated assemblies of chiral 5´DSCG-diviol were able to interact with each other across a 6 nm separation in aqueous environment and the chirality information was transmitted through achiral medium. Chapter 3 describes the synthesis and biological studies of a class of bicyclic brominated furanones. These molecules interacted with quorum sensing in an opportunistic pathogen P. aeruginosa. Some representative compounds in this class inhibited quorum sensing-controlled activities such as biofilm formation and virulence factor production, which were key factors in the pathogenicity of the bacteria. These compounds exhibited significant reduction in the toxicity of human neuroblastoma SK-N-SH and did not inhibit bacterial growth. Furthermore, one compound, 6-BBF, significantly improved P. aeruginosa clearance in the lungs of mice in an immunocompromised pneumonia mouse model in vivo. Chapter 4 reports the synthesis of a library of squarylated homoserine lactones (SHLs) as analogues to the natural autoinducers N-acyl homoserine lactones (AHL) in Gram-negative bacteria. These SHLs were shown to have no or minimal impact of the growth of P. aeruginosa and V. fischeri, but maintain the abilities to modulate quorum sensing and inhibit biofilm formation. Primary studies of structural activity relationship revealed that the alkyl chain length was critical to activities of SHLs. These SHLs are promising candidates as modulators of other AHL-mediated QS systems

Cultural impacts on traditional Chinese garden design: A configurational comparison between traditional Chinese imperial and private gardens using space syntax

Based on former qualitative studies, traditional Chinese imperial garden (TCIG) and private garden (TCPG) arguably have different cultural backgrounds and spatial properties. However, few studies have analysed configurational differences between TCIG and TCPG quantitatively and linked their different cultural contexts to these differences. This research thus tries to reveal the cultural impacts on the spatial configuration of traditional Chinese gardens by comparing TCIG and TCPG cases quantitatively. The study is processed in two sections: theoretical exploration and comparative case studies. In the first section, we try to link the different cultural backgrounds of TCIG and TCPG with corresponding garden spatial properties and use proper metrics to match these spatial properties. Four dimensions of traditional Chinese garden spatial properties are identified qualitatively based on previous studies: strong and weak programme, wayfinding system, visual relationship and spatial depth. During the process, four corresponding hypotheses about the spatial property differences and predicted results of quantitative studies are proposed. In the second section, four hypotheses may be demonstrated through visibility graph analysis (VGA) in space syntax theory by comparing three samples from each garden type. Our results indicate that TCIG and TCPG differ in all four dimensions, which are further explained by their respective cultural contexts. This research has two main contributions. Firstly, it has demonstrated configurational differences of TCIG and TCPG quantitatively and linked these differences to related cultural backgrounds. Secondly, this study has built a framework to analyse traditional Chinese garden space with space syntax, which can be used in further studies

Design of a microelectromechanical systems microgripper with integrated electrothermal actuator and force sensor

This article presents the conceptual design of a novel compliant microelectromechanical systems (MEMS)-based gripper with integrated electrothermal actuator and electrothermal force sensor. By this design solution, the device possesses some unique characteristics including a small and compact footprint size, and a large driving force by the thermal actuator. Owing to the use of a compliant rotational bearing, a large gripping range is obtained. The sensing arm has a capability of detecting the force transmitted from the left arm so as to prevent the damage of the grasped object. Analytical models are developed to evaluate the statics and dynamics performance of the gripper. Simulation results show that the thermal actuator produces sufficient gripping force to execute the gripping operation with a range of 80 µm under a low input voltage of 6 V. Moreover, the results of the established theoretical models match well with the finite element analysis (FEA) simulation results, which verifies the feasibility of the proposed gripper design. </jats:p

Trajectory tracking control based on adaptive neural dynamics for four-wheel drive omnidirectional mobile robots

There is usually the speed jump problem existing in conventional back-stepping tracking control for four-wheel drive omni-directional mobile robots, a trajectory tracking controller based on adaptive neural dynamics model is proposed. Because of the smoothness and boundedness of the output from the neural dynamics model, it produces a gradually varying tracking speed instead of the jumping speed, and the parameters are designed to avoid the control values exceeding their limits. And then, a parameter adaptive controller is presented to improve control performance. Simulation results of different paths and comparison with the conventional back-stepping technique show that the approach is effective, and the system has a good performance with smooth output

Trajectory tracking control based on adaptive neural dynamics for four-wheel drive omnidirectional mobile robots

There is usually the speed jump problem existing in conventional back-stepping tracking control for four-wheel drive omni-directional mobile robots, a trajectory tracking controller based on adaptive neural dynamics model is proposed. Because of the smoothness and boundedness of the output from the neural dynamics model, it produces a gradually varying tracking speed instead of the jumping speed, and the parameters are designed to avoid the control values exceeding their limits. And then, a parameter adaptive controller is presented to improve control performance. Simulation results of different paths and comparison with the conventional back-stepping technique show that the approach is effective, and the system has a good performance with smooth output

Communicative Message Passing for Inductive Relation Reasoning

Relation prediction for knowledge graphs aims at predicting missing relationships between entities. Despite the importance of inductive relation prediction, most previous works are limited to a transductive setting and cannot process previously unseen entities. The recent proposed subgraph-based relation reasoning models provided alternatives to predict links from the subgraph structure surrounding a candidate triplet inductively. However, we observe that these methods often neglect the directed nature of the extracted subgraph and weaken the role of relation information in the subgraph modeling. As a result, they fail to effectively handle the asymmetric/anti-symmetric triplets and produce insufficient embeddings for the target triplets. To this end, we introduce a \textbf{C}\textbf{o}mmunicative \textbf{M}essage \textbf{P}assing neural network for \textbf{I}nductive re\textbf{L}ation r\textbf{E}asoning, \textbf{CoMPILE}, that reasons over local directed subgraph structures and has a vigorous inductive bias to process entity-independent semantic relations. In contrast to existing models, CoMPILE strengthens the message interactions between edges and entitles through a communicative kernel and enables a sufficient flow of relation information. Moreover, we demonstrate that CoMPILE can naturally handle asymmetric/anti-symmetric relations without the need for explosively increasing the number of model parameters by extracting the directed enclosing subgraphs. Extensive experiments show substantial performance gains in comparison to state-of-the-art methods on commonly used benchmark datasets with variant inductive settings.Comment: Accepted by AAAI-202