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Recent technological advances in micro-robotic systems have demonstrated much potential for biomedical applications. These include diagnostics at the cellular level, drug delivery and microsurgery. Similar to the manipulation in macro-scale robotics, dexterous manipulation is one of the most active areas to study for micro-robotics, where new approaches and technologies are explored to manipulate micro-objects or microrobots for different purposes. Although recent work has shown the potential of microrobots in biomedical applications, significant technical challenges remain to be solved. Micromanipulators cannot be considered as the simple scaling down version from the large-scale manipulators, since they do not have the same capabilities of 6 Degrees-of-Freedom (6 DoFs) manipulation in three-dimensional (3D) space and accurate on-board sensing for 6 DoFs pose estimation as per macroscale robotic systems. Therefore, the perception and manipulation of microrobots should be further explored. Micro-robotic systems include tethered and untethered microrobots. Among untethered micromanipulation, optical manipulation is one of the most accurate approaches and has been demonstrated in applications such as cell analysis and manipulation. Optical tweezer (OT) is a versatile tool for optical manipulation, and is the main focus of this thesis. To avoid damages to living cells caused by illuminating laser directly on them, optical microrobots controlled by OT can be used for indirect manipulation of biological objects in micro-scale. To develop a dexterous micro-robotic platform for biomedical research, perception and manipulation of untethered optical microrobots via OT are two key aspects to be studied. Such optical microrobot could enable 6 DoFs dexterous manipulation in a closed environment such as inside a microfluidic chip. It can also assist cell surgery by transporting and orientating cells or other biological objects to the desired pose. The main target of this thesis is to design and build an OT based micro-robotic system to enable 6 DoFs micromanipulation with accurate depth and pose estimation. Multiple optical traps are used as contactless robotic manipulators' end-effectors, which form a distributed control scheme. The main contributions of the thesis are listed as follows: i) Design and modeling of microrobots with complex shapes are investigated for the implementation of out-of-plane control, ii) Machine learning based algorithms for depth estimation and pose estimation are developed for microrobot monitoring during the optical manipulation, iii) Two control strategies for distributed force control of optical microrobots are developed while a potential application of indirect manipulation using the proposed OT based framework is demonstrated.

The purpose of this thesis is to look into the Leavis-Eliot relationship, connecting it with the broader discourse of English Studies as a university subject that developed in the first half of the twentieth century. It surveys all the many writings of Leavis on Eliot, to see how Eliot is formative for the theory and practice of Leavis’s literary criticism in both positive and negative ways. It conducts a detailed investigation of D. H. Lawrence’s significance in relation to Leavis’s changing attitude to Eliot, and examines how profound differences in social, cultural, religious and national thinking strengthened Leavis’s alliance with Lawrence to the detriment of his relationship with Eliot. These differences are presented as dichotomies between nationalism and Europeanism or internationalism, ruralism or organicism and industrialisation or metropolitanism, and relate to the differences between the two men’s views about literary education, the subject of English and the position of the classics in the curriculum. Leavis’s increasingly conflicted feelings towards a figure to whom he owned an enormous critical debt and inspiration, but whose various beliefs and literary affiliations caused him much misgiving, results in a deep sense of division in Leavis himself which he sought to transfer onto Eliot.

Semiconductor nanomaterials have become an important class of materials with great potential for applications ranging from catalytic to electronic and optoelectronic devices. For next generation catalytic, optoelectronic, and photonic applications, the synthesis of high-qualify nanomaterials with uniform size, well-defined morphology, composition, and surface chemistry is of key importance, because the electrical, optical, and magnetic properties of these nanomaterials are strongly dependent on those parameters. Besides technical interests, access to defined nanoscale structures is also essential for uncovering their intrinsic properties unaffected by sample heterogeneity. Rigorous understanding of the properties of individual nanocrystals will enable us to exploit them, making it possible to better design and build novel electronic, magnetic, and photonic devices and other functional materials based on these nanostructures.This dissertation explores both direct synthetic methods and post transformation approaches for rational synthesis of new nanomaterial systems, which are potential candidates for applications in areas of photovoltaics, non-noble-metal plasmonics, light emitting diodes, etc. And their structural, optical, and electrical properties have been investigated in detail. Chapter 1 provides an introduction to the current progress and common strategies used in rational control of the size, shape, composition, and surface chemistry of nanomaterials. Chapter 2 examines the Cu+ cation-exchange mechanisms in CdS nanowires. A detailed transformation diagram of cation-exchange chemistry from CdS to Cu2-xS nanowires is reported. By varying the reaction time and the reactants’ concentration ratio, the progression of the cation-exchange process was captured, and tunable crystal phases of the Cu2-xS are achieved. The overall process occurs in three stages: formation of discontinuous Cu2-xS islands, formation of core-shell CdS-Cu2-xS heterostructures, and complete conversion to Cu2-xS nanowires with controllable crystal phases. Detailed structural characterization reveal that the resultant Cu2-xS phases become more stoichiometric with increasing reaction time and copper precursor concentration. This experimental result suggests a kinetically controlled process limited by diffusion. In Chapter 3, a catalyst-free, solution-phase approach has been developed to obtain single crystalline, orthorhombic CsPbX3 NWs with uniform growth direction. The morphological evolution of the CsPbBr3 nanostructures along the reaction has been investigated, and the reaction protocol has been optimized to achieve a high yield of monodispersed nanowires likely due to a soft template mechanism. The direct synthesized CsPbI3 NWs show a room-temperature stable double-chain phase, with weak photoluminescence mainly from the trap states. Anion-exchange reaction by using the monodispersed CsPbBr3 NWs as templates can retain the favorable corner-sharing orthorhombic phase, and independently control the NW compositions, thus access to a wide range of compositions with bright and tunable photoluminescence spanning over nearly the entire visible spectrum. Meanwhile, surface treatment with the original precursors was performed to effectively passivate the surface states, and improve the quantum yield to over 10 times. In Chapter 4, a stepwise purification method has been developed to purify the ultrathin CsPbX3 NWs with a uniform diameter of 2.2±0.2 nm. The structural and optical properties have been discussed. Aberration-corrected high-resolution TEM shows the NWs are single crystalline, absorption and fluorescence spectrum shows that those NWs possess strong two-dimensional quantum confinement effects along with bright emission. The band gap of these ultrathin NWs can be tuned by anion-exchange reaction.