493 research outputs found
Light beaming from a single subwavelength metal slit
In this thesis, light transmission through a single sub-wavelength slit in a silver thin film with periodic gratings at the exit side of the slit has been studied in both the visible and mid-infrared wavelength ranges. In the visible wavelength range, we first investigate the enhancement of plasmonic light beaming efficiency by near field resonance in a subwavelength metallic slit-groove beaming structure. We show that by varying the film thickness and the separation distance of the beaming grating, the intensity of the near field can be greatly enhanced by resonance, which leads to the increase of the beaming efficiency. Moreover, we obtain a nanocavity above the nanoslit by integrating a metal nanostrip with the beaming structure. The resonance of this nanocavity can further enhance the near field intensity and improve the beaming efficiency. We also show that light beaming in mid-infrared is mainly controlled by \u27spoof\u27 surface plasmons. We take account of both the dispersion relation and the phase-matching condition of \u27spoof\u27 surface plasmons to obtain good beaming efficiency. Through engineering the geometry of the grating structures, we can achieve the desired near field and far field distribution in mid-infrared
ENVIRONMENTAL AND BIOLOGICAL APPLICATIONS AND IMPLICATIONS OF SOFT AND CONDENSED NANOMATERIALS
Recent innovations and growth of nanotechnology have spurred exciting technological and commercial developments of nanomaterails. Their appealing physical and physicochemical properties offer great opportunities in biological and environmental applications, while in the meantime may compromise human health and environmental sustainability through either unintentional exposure or intentional discharge. Accordingly, this dissertation exploits the physicochemical behavior of soft dendritic polymers for environmental remediation and condensed nano ZnO tetrapods for biological sensing (Chapter two-four), and further delineate the environmental implications of such nanomaterials using algae- the major constituent of the aquatic food chain-as a model system (Chapter five). This dissertation is presented as follows. Chapter one presents a general review of the characteristic properties, applications, forces dictating nanomaterials, and their biological and environmental implications of the most produced and studied soft and condensed nanomaterials. In addition, dendritic polymers and ZnO nanomaterials are thoroughly reviewed separately. Chapter two investigates the physicochemical properties of poly(amidoamine)-tris(hydroxymethyl)amidomethane- dendrimer for its potential applications in water purification. The binding mechanisms and capacities of this dendrimer in hosting major environmental pollutants including cationic copper, anionic nitrate, and polyaromatic phenanthrene are discussed. Chapter three exploits a promising use of dendrimers for removal of potentially harmful discharged nanoparticles (NPs). Specifically, fullerenols are used as a model nanomaterial, and their interactions with two different generations of dendrimers are studied using spectrophotometry and thermodynamics methods. Chapter four elucidates two novel optical schemes for sensing environmental pollutants and biological compounds using dendrimer-gold nanowire complex and gold-coated ZnO tetrapods, respectively. The surface plasmon resonance of gold nanowires and NPs are utilized for enhancing the detection limits of Cu(II) down to nanomolar level and protein/lipids down to picomolar level. Chapter five justifies the growing concern of the environmental implications of nanomaterials in light of the increasing environmental and biological applications of nanomaterials based on the previous chapters, using ZnO NPs and single-celled green algae, Chlorella sp. as a model system. Chapter six summarized the key findings in this dissertation and presents future work stimulated by this Doctor of Philosophy (PhD) research. In summary, the key scientific contributions of this dissertation are: 1). we have performed the first study on the versatility of a trifunctional dendrimer for hosting cationic, anionic, and polyaromatic chemical contaminants; 2). we have demonstrated for the first time the concept that a soft, biocompatible nanoparticle--a dendrimer, can be used for hosting discharged, harmful nanoparticles for environmental remediation; and 3). we have shown for the first time the impact of nanoparticles on aquatic organisms is bidirectional
A Study on the Translation Methods of Social Culture-Loaded Words in Yang Xianyi and Gladys Yang’s Translation of Call to Arms From the Perspective of Hermeneutics
It has been almost twenty years since hermeneutics is first introduced into China, providing comprehensive and diverse interpretations for some phenomena or expressions in translation process, especially for culture-loaded words in many literary works. Call to Arms is a very famous literary novel written by Luxun which contains a great number of culture-loaded words, including many social culture-loaded words which imply much meaningful social and cultural connotations. Yang Xianyi and Gladys Yang successfully use different translation methods related with hermeneutics in the translation of Call to Arms. By analyzing the translation methods of social culture-loaded words in Call to Arms’ English translation from the perspective of hermeneutics, how the translators subtly use different translation methods to embody the three principles of hermeneutics can be reflected in terms of achieving different translation effects
INACTIVATION AND REPAIR OF ENTEROCOCCUS FAECALIS AND VIBRIO CHOLERA BY UV FOR BALLAST WATER TREATMENT
Master'sMASTER OF SCIENC
Characterizing the Influence of Graph Elements
Influence function, a method from robust statistics, measures the changes of
model parameters or some functions about model parameters concerning the
removal or modification of training instances. It is an efficient and useful
post-hoc method for studying the interpretability of machine learning models
without the need for expensive model re-training. Recently, graph convolution
networks (GCNs), which operate on graph data, have attracted a great deal of
attention. However, there is no preceding research on the influence functions
of GCNs to shed light on the effects of removing training nodes/edges from an
input graph. Since the nodes/edges in a graph are interdependent in GCNs, it is
challenging to derive influence functions for GCNs. To fill this gap, we
started with the simple graph convolution (SGC) model that operates on an
attributed graph and formulated an influence function to approximate the
changes in model parameters when a node or an edge is removed from an
attributed graph. Moreover, we theoretically analyzed the error bound of the
estimated influence of removing an edge. We experimentally validated the
accuracy and effectiveness of our influence estimation function. In addition,
we showed that the influence function of an SGC model could be used to estimate
the impact of removing training nodes/edges on the test performance of the SGC
without re-training the model. Finally, we demonstrated how to use influence
functions to guide the adversarial attacks on GCNs effectively
An observer-based type-3 fuzzy control for non-holonomic wheeled robots
Non-holonomic wheeled robots (NWR) comprise a type of robotic system; they use wheels
for movement and offer several advantages over other types. They are efficient, highly, and maneuverable, making them ideal for factory automation, logistics, transportation, and healthcare. The control of this type of robot is complicated, due to the complexity of modeling, asymmetrical non-holonomic constraints, and unknown perturbations in various applications. Therefore, in this study, a novel type-3 (T3) fuzzy logic system (FLS)-based controller is developed for NWRs. T3-FLSs are employed for modeling, and the modeling errors are considered in stability analysis based on the symmetric Lyapunov function. An observer is designed to detect the error, and its effect is eliminated by a developed terminal sliding mode controller (SMC). The designed technique is used to control a case-study NWR, and the results demonstrate the good accuracy of the developed scheme under non-holonomic constraints, unknown dynamics, and nonlinear disturbances
Fundamental Limitation on the Detectability of Entanglement
Entanglement detection is essential in quantum information science and
quantum many-body physics. It has been proved that entanglement exists almost
surely for a random quantum state, while the realizations of effective
entanglement criteria usually consume exponential resources, and efficient
criteria often perform poorly without prior knowledge. This fact implies a
fundamental limitation might exist in the detectability of entanglement. In
this work, we formalize this limitation as a fundamental trade-off between the
efficiency and effectiveness of entanglement criteria via a systematic method
to theoretically evaluate the detection capability of entanglement criteria.
For a system coupled to an environment, we prove that any entanglement
criterion needs exponentially many observables to detect the entanglement
effectively when restricted to single-copy operations. Otherwise, the detection
capability of the criterion will decay double-exponentially. Furthermore, if
multi-copy joint measurements are allowed, the effectiveness of entanglement
detection can be exponentially improved, which implies a quantum advantage in
entanglement detection problems.Comment: 16 pages, 7 figure
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