Functionalization of molecules in confined space

Light-driven molecular motors are unique photoresponsive molecules which can undergo continuous 360 degree unidirectional rotation. However, most of the studies on molecular motors thus far have been conducted in solution and focused on their multi-stage switching behavior. On the other hand, existing reports on photoswitches have revealed that cooperative effects may arise via incorporation into host architectures, which differentiate the assembled systems from simple photoswitching molecules. Aiming to obtain specific functions of motor-based systems, this thesis predominantly focuses on the functionalization of molecular motors into confined space, in aggregates and on particle surfaces. While studying the rotary behavior of motors, we also focus on the cooperative effects that these assembled systems generate. In addition, in these systems, we have made initial attempts to utilize the dynamic rotary motion of molecular motors to perform work

Effect of interaction with neutrons in matter on flavor conversion of super-light sterile neutrino with active neutrino

A super-light sterile neutrino was proposed to explain the absence of the expected upturn of the survival probability of low energy solar boron neutrinos. This is because this super-light sterile neutrino can oscillate efficiently with electron neutrino through a MSW resonance happened in Sun. One may naturally expect that a similar resonance should happen for neutrinos propagating in Earth matter. We study the flavor conversion of this super-light sterile neutrino with active neutrinos in Earth matter. We find that the scenario of the super-light sterile neutrino can easily pass through possible constraints from experiments which can test the Earth matter effect in oscillation of neutrinos. Interestinlgy, we find that this is because the naively expected resonant conversion disappears or is significantly suppressed due to the presence of a potential $V_n$ which arises from neutral current interaction of neutrino with neutrons in matter. In contrast, the neutron number density in the Sun is negligible and the effect of $V_n$ is effectively switched off. This enables the MSW resonance in Sun needed in oscillation of the super-light sterile neutrino with solar electron neutrinos. It's interesting to note that it is the different situation in the Sun and in the Earth that makes $V_n$ effectively turned off and turned on respectively. This observation makes the scenario of the super-light sterile neutrino quite interesting.Comment: 22 pages, 10 figure

Phenomenological model for coupled multi-axial piezoelectricity

A quantitative calibration of an existing phenomenological model for polycrystalline ferroelectric ceramics is presented. The model relies on remnant strain and polarization as independent variables. Innovative experimental and numerical model identification procedures are developed for the characterization of the coupled electro-mechanical, multi-axial nonlinear constitutive law. Experiments were conducted on thin PZT-5A4E plates subjected to cross-thickness electric field. Unimorph structures with different thickness ratios between PZT-5A4E plate and substrate were tested, to subject the piezo plates to coupled electro-mechanical fields. Material state histories in electric field-strain-polarization space and stress-strain-polarization space were recorded. An optimization procedure is employed for the determination of the model parameters, and the calibrated constitutive law predicts both the uncoupled and coupled experimental observations accurately

Supramolecular control over self-assembly and double thermoresponsive behavior of an amphiphilic block copolymer

A poly(ethylene glycol)-b-poly[N, N-dimethylacrylamide-ran-2-acrylamidoethyl nonanoate] (PEG-b-P(DMA-AAEN)) block copolymer has been demonstrated to show double thermoresponsive behavior in aqueous solution in the presence of hydroxypropylated cyclodextrin (HPCD). The polymer itself is insoluble in water due to the presence of hydrophobic alkyl chain, however, with the presence of HPCD, fully dissolution of the polymer could be obtained indicating the formation of host-guest interaction between HPCD and the alkyl chain. The clear solution of HPCD/polymer complex showing a first thermoresponsiveness during heating and led to the formation of small micelles stabilized by PEG chains and DMA segments. Upon further heating of the aqueous solution, the small micelles aggregated and formed multimicellar aggregates. The reported double thermoresponsive behavior may provide a new strategy of designing smart polymeric systems, which can find broad applications in the fabrication of smart materials

Few-shot Multi-domain Knowledge Rearming for Context-aware Defence against Advanced Persistent Threats

Advanced persistent threats (APTs) have novel features such as multi-stage penetration, highly-tailored intention, and evasive tactics. APTs defense requires fusing multi-dimensional Cyber threat intelligence data to identify attack intentions and conducts efficient knowledge discovery strategies by data-driven machine learning to recognize entity relationships. However, data-driven machine learning lacks generalization ability on fresh or unknown samples, reducing the accuracy and practicality of the defense model. Besides, the private deployment of these APT defense models on heterogeneous environments and various network devices requires significant investment in context awareness (such as known attack entities, continuous network states, and current security strategies). In this paper, we propose a few-shot multi-domain knowledge rearming (FMKR) scheme for context-aware defense against APTs. By completing multiple small tasks that are generated from different network domains with meta-learning, the FMKR firstly trains a model with good discrimination and generalization ability for fresh and unknown APT attacks. In each FMKR task, both threat intelligence and local entities are fused into the support/query sets in meta-learning to identify possible attack stages. Secondly, to rearm current security strategies, an finetuning-based deployment mechanism is proposed to transfer learned knowledge into the student model, while minimizing the defense cost. Compared to multiple model replacement strategies, the FMKR provides a faster response to attack behaviors while consuming less scheduling cost. Based on the feedback from multiple real users of the Industrial Internet of Things (IIoT) over 2 months, we demonstrate that the proposed scheme can improve the defense satisfaction rate.Comment: It has been accepted by IEEE SmartNet

Phenomenological model for coupled multi-axial piezoelectricity

A quantitative calibration of an existing phenomenological model for polycrystalline ferroelectric ceramics is presented. The model relies on remnant strain and polarization as independent variables. Innovative experimental and numerical model identification procedures are developed for the characterization of the coupled electro-mechanical, multi-axial nonlinear constitutive law. Experiments were conducted on thin PZT-5A4E plates subjected to cross-thickness electric field. Unimorph structures with different thickness ratios between PZT-5A4E plate and substrate were tested, to subject the piezo plates to coupled electro-mechanical fields. Material state histories in electric field-strain-polarization space and stress-strain-polarization space were recorded. An optimization procedure is employed for the determination of the model parameters, and the calibrated constitutive law predicts both the uncoupled and coupled experimental observations accurately