Chirality in gold-LC nanocomposites and heliconical systems

The research presented in this thesis is focused towards the design and synthesis of chiral liquid crystal gold nanoparticle nanocomposites and all of the related molecular sub-structures. It is intended that such organic-inorganic hybrid materials will combine the good processing properties of liquid crystals, such as forming soft anisometric condensed matter, low cost and photolithographic patterning, together with the unique optically plasmonic behaviour of nanoscale metal nanoparticles to interact with circularly polarized light.The synthetic methods of mesogenic ligands: calamitic mesogen with thiol end and discogen with disulfide function, were carried out and optimized to increase the yield, convenience and compatibility of soft ligands on solid gold. A synchrotron radiation circular dichroism technique was used here to detect the structural twist of collective NP assembly. The chiral transfer of functionalized AuNPs was investigated in calamitic hosts to realize the detection, visualization, measurement and quantification of chirality based on systematic optical observation. Macroscopic liquid crystal behaviour was observed for the undiluted gold nanoparticles organic-modified by the designed chiral discogen. Extended explorations on nematic twist-bend phase via circular dichroism mapping methods demonstrated the presence of doubly degenerate domains with opposite handedness. Besides, the chiral effects on bent-shaped dimer experimentally induced a new phase between cholesteric phase and NTB phase, which was confirmed by OPM and DSC tests

Two helices from one chiral centre – self organization of disc shaped chiral nanoparticles

Gold nanoparticles (AuNPs) have been prepared and surfacefunctionalizedwith a mixture of 1-hexanethiol co-ligands and chiraldiscogen ligands separated from a disulfide function via a flexiblespacer. Polarized optical microscopy together with differentialscanning calorimetry showed that the organic corona of thenanocomposite forms a stable chiral discotic nematic (ND*) phasewith a wide thermal range. Synchrotron X-ray diffraction showedthat gold NPs form a superlattice with p2 plane symmetry. Analysisindicated that the corona takes up the shape of a flexiblemacrodisk. Synchrotron radiation-based circular dichroism signalsof thin films are significantly enhanced on the isotropic-LCtransition in line with the formation of a chiral nematic phase of theorganic corona. At lower temperatures the appearance of CDsignals associated with the NPs is indicative of the formation of asecond helical structure. The decreased volume required and thechiral environment of the disc ligands drives the nanoparticles intocolumns that arrange helically parallel to the shortest axis of thetwo dimensional lattice

Chirality enhancement in macro-chiral liquid crystal nanoparticles

The amplification of molecular chirality by metal nanoparticles (NPs) is an important and rapidly evolving field in nanomaterial research with wide applications in smart materials, catalysis, and solvent-solute interactions. Here we present the results of the synthesis of gold nanoparticles (AuNPs) functionalized both with chiral ligands based on the binaphthol motif and with nematogenic groups (ChirAuLC). The materials were characterized chemically and the ratios between chiral groups and LC groups was determined. Synchrotron radiation circular dichroism (SRCD) and synchrotron based X-ray diffraction (XRD) studies show that the AuNPs favoured by the LC state arrange themselves into ordered columns and a helical superstructure appears in the mesophase of collective NPs. A specific focus has been the investigation of the chiral induction of ChirAuLC composites in two different nematic LC hosts. For a number of selected mixtures, the helical twisting power (HTP) of these NPs in systems was calculated from systematic optical observations based on optical polarizing microscopy (OPM). The experimental data show that the HTP of the investigated ChirAuLC composite is significantly larger than that of free "small molecule"chiral groups when dispersed in the same LC host and the chiral transfer efficiency of ChirAuLC is higher than NPs functionalized only with chiral groups (ChirAuNP). This is new and can be explained by a combination of a surface chirality and the domino effect of bound mesogens interacting with the bulk. This journal i

Optimization of Hybrid Energy Storage Systems at the Building Level with Combined Heat and Power Generation

The average daily benefit to cost ratio of a building energy storage system is mainly constrained by the battery lifetime. This paper aims to minimize the average daily cost of a hybrid energy storage system (HESS) (comprised of a battery and supercapacitor) by optimizing the battery capacity. A novel optimization model is proposed with the objective to find the minimum average daily investment cost of the HESS. The objective function has two parts: (1) the investment cost formula for the battery is derived as a function of the battery capacity, which has an interdependence with the minimum state of charge (SOC) and the maximum discharge current; (2) the investment cost formula for the supercapacitor is also established as a function of battery capacity by matching the maximum battery power with that of the supercapacitor. Case studies demonstrate several ways to increase the average daily benefit to cost ratio: (1) adopting a suitable control strategy to avoid capacity saturation; (2) reducing the battery SOC to increase the threshold for the maximum discharge current (MDC) saturation; and (3) increasing MDC to raise the threshold for the SOC saturation. Results show that the average daily benefit to cost ratio is doubled compared to previous work

Enzyme-Catalytic Self-Triggered Release of Drugs from a Nanosystem for Efficient Delivery to Nuclei of Tumor Cells.

Stimulus-responsive drug delivery nanosystems (DDSs) are of great significance in improving cancer therapy for intelligent control over drug release. However, among them, many DDSs are unable to realize rapid and sufficient drug release because most internal stimulants might be consumed during the release process. To address the plight, an abundant supply of stimulants is highly desirable. Herein, a core crosslinked pullulan-di-(4,1-hydroxybenzylene)diselenide nanosystem, which could generate abundant exogenous-stimulant reactive oxygen species (ROS) via tumor-specific NAD(P)H:quinone oxidoreductase-1 (NQO1) catalysis, was constructed by the encapsulation of β-lapachone. The enzyme-catalytic-generated ROS induced self-triggered cascade amplification release of loaded doxorubicin (DOX) in the tumor cells, thus achieving efficient delivery of DOX to the nuclei of tumor cells by breaking the diselenide bond of the nanosystem. As a result, the antitumor effect of this nanosystem was significantly improved in the HepG2 xenograft model. In general, this study offers a new paradigm for utilizing the interaction between the loaded agent and carrier in the tumor cells to obtain self-triggered drug release in the design of DDSs for enhanced cancer therapy

Review of advanced road materials, structures, equipment, and detection technologies

As a vital and integral component of transportation infrastructure, pavement has a direct and tangible impact on socio-economic sustainability. In recent years, an influx of groundbreaking and state-of-the-art materials, structures, equipment, and detection technologies related to road engineering have continually and progressively emerged, reshaping the landscape of pavement systems. There is a pressing and growing need for a timely summarization of the current research status and a clear identification of future research directions in these advanced and evolving technologies. Therefore, Journal of Road Engineering has undertaken the significant initiative of introducing a comprehensive review paper with the overarching theme of “advanced road materials, structures, equipment, and detection technologies”. This extensive and insightful review meticulously gathers and synthesizes research findings from 39 distinguished scholars, all of whom are affiliated with 19 renowned universities or research institutions specializing in the diverse and multidimensional field of highway engineering. It covers the current state and anticipates future development directions in the four major and interconnected domains of road engineering: advanced road materials, advanced road structures and performance evaluation, advanced road construction equipment and technology, and advanced road detection and assessment technologies

DESIGN AND CHARACTERIZATION OF ASPHALT MIXTURES BASED ON PARTICLE PACKING AND MECHANICAL MODELING

Existing asphalt mixture design approaches are mainly empirical based "trial-and-error" methods. Based purely on volumetrics, such design methods have little consideration of the mechanical performance of the mixtures. With the trend of moving the pavement research into more mechanistic based methods and targeting the ultimate goal to good field performance, it is necessary to develop a sophisticated mix design and characterization methodology which can help the designer understand the expected engineering performance of the mix at the early stages, at the same time, to have a more efficient tool to evaluate the quality of the mixtures. This research develops a comprehensive aggregate gradation and asphalt mixture design method that estimates the mechanical properties of the mix at early stage. In this method, strong correlations between aggregate properties, volumetrics, and mechanical properties are identified, making the VMA (Voids in Mineral Aggregate) an excellent media to link the properties of aggregates and asphalt binder to their engineering performance. The concept of the design procedure, especially the aggregate gradation design procedure, is largely based on an analysis of aggregate packing and interlocking. As a fast and convenient design method that emphasizes more on the mechanical performance of the mix, the new design method can be used to evaluate the quality of an existing gradation and mix design, and adjust the gradation of a new mix to satisfy both volumetrics and mechanical properties. In addition, the characteristics of asphalt mixture are studied using micromechanical based discrete element method (DEM) and macromechanical modeling. In DEM simulation, an image based ball clumping technique is used for simulating the angularity properties of aggregate particles. The DEM model is established and calibrated to describe the viscoelastic (dynamic modulus and phase angle) and viscoelastic plastic (strength) properties of asphalt mixtures with or without damage involved. As for macromechanical modeling, a constitutive model for characterizing the permanent deformation of asphalt mixture is explored by taking consideration of the directional distribution of aggregates (anisotropy), and the damage induced by plasticity

A facile synthesis of a room-temperature chiral discotic nematic liquid crystal based on pentaalkynylbenzene core

The preparation of discotic liquid crystal with a wide thermal nematic phase range remains a challenge. Here, a method to synthesise a class of discotic liquid crystal with exclusive and stable chiral nematic phase over a wide temperature range, based on pentaalkynylbenzene core, is presented and the mesogenic properties are well studied