Host-Guest Systems and Their Derivatives Based on Metal-Organic Frameworks

Including guest compounds inside the pores of nanoporous crystalline hosts (e.g. zeolite) is a key strategy to post-synthetically functionalise these nanoporous materials over past half a century. It yields highly active and stable heterogeneous catalysts as well as robust materials with tuneable photoluminescence properties due to geometric/quantum confinement. More recently, metal-organic frameworks (MOFs), which are hybrid hosts assembled with metal centres and organic ligands, start to be considered for creating host-guest composites. Apart from the aforementioned confinement effects, MOFs with diverse chemistries as hosts can give rise to a variety of host-guest interactions in these composite systems. It is, however, challenging to investigate these MOF-guest systems due to small MOF pore dimensions, MOF instability, poor guest loading control and limitations in guest characterisations. The thesis explores three different MOF-guest systems covering their preparation, characterisation as well as some unusual behaviour owing to MOF-guest interactions and/or confinement effects. The first system is incorporating electrically conducting poly(3,4-ethylenedioxythiophene) (PEDOT) into a $Zn_2(1,4-ndc)_2(dabco)$ ($1,4-ndc = 1,4-naphthalenedicarboxylate$, $dabco = 1,4-diazabicyclo[2.2.2]octane$) $[PEDOT@Zn_2(1,4-ndc)_2(dabco)]$, which turned the electrically insulating MOF into a semiconducting composite. The formation of nanostructured PEDOT by removing the MOF from the $PEDOT@Zn_2(1,4-ndc)_2(dabco)$ is also demonstrated. The success in MOF-PEDOT system preparation is the motivation to expand the synthesis to forming inorganic guests (the second system). Thermodynamically favourable solid/solution phases of inorganic compounds, which relate to electrochemical potential and pH, are considered to choose reaction agents and conditions to form desired guests. The application of the concept to the synthesis of $MOF-RuO_2$ catalysts ($RuO_2@MOF-808-P$), where the confined $RuO_2@MOF-808-P$ has exceptionally high activity for CO oxidation compared to unconfined $RuO_2$ with poor activity at low temperatures ($\le$150 °C) is demonstrated. In the final system, guest-induced metamorphosis by carbonising the MOF-guest composites made of HKUST-1-type MOFs and thiomolybdates is unveiled. With implications for the transformation mechanisms, MOF- and guest-dependent morphology of the carbonised products are shown. The carbonised product based upon HKUST-1(Cu) and thiomolybdate was also demonstrated as lithium-ion battery anode.China Scholarship Council (CSC); EPSRC Centre for Doctoral Training in Sensor Technologies and Applications (EP/ L015889/1 and 1566990)

Development of a time-to-digital converter ASIC for the upgrade of the ATLAS Monitored Drift Tube detector

The upgrade of the ATLAS muon spectrometer for high-luminosity LHC requires new trigger and readout electronics for the various elements of the detector. We present the design of a time-to-digital converter (TDC) ASIC prototype for the ATLAS Monitored Drift Tube (MDT) detector. The chip was fabricated in a GlobalFoundries 130 nm CMOS technology. Studies indicate that its timing and power consumption characteristics meet the design specifications, with a timing bin variation of 40 ps for all 48 channels with a power consumption of about 6.5 mW per channel.Comment: 9 pages, 12 figure

Fault-Tolerant Electro-Responsive Surfaces for Dynamic Micropattern Molds and Tunable Optics.

Electrically deformable surfaces based on dielectric elastomers have recently demonstrated controllable microscale roughness, ease of operation, fast response, and possibilities for programmable control. Potential applications include marine anti-biofouling, dynamic pattern generation, and voltage-controlled smart windows. Most of these systems, however, exhibit limited durability due to irreversible dielectric breakdown. Lowering device voltage to avoid this issue is hindered by an inadequate understanding of the electrically-induced wrinkling deformation as a function of the deformable elastic film thickness. Here we report responsive surfaces that overcome these shortcomings: we achieve fault-tolerant behavior based on the ability to self-insulate breakdown faults, and we enhance fundamental understanding of the system by quantifying the critical field necessary to induce wrinkles in films of different thickness and comparing to analytical models. We also observe new capabilities of these responsive surfaces, such as field amplification near local breakdown sites, which enable actuation and wrinkle pattern formation at lower applied voltages. We demonstrate the wide applicability of our responsive, fault-tolerant films by using our system for adjustable transparency films, tunable diffraction gratings, and a dynamic surface template/factory from which various static micropatterns can be molded on demand

Object Tracking using Incremental 2D-PCA Learning and ML Estimation

Video surveillance has drawn increasing interests in recent years. This paper addresses the issue of moving object tracking from videos. A two-step processing procedure is proposed: an incremental 2DPCA (two-dimensional PrincipalComponent Analysis)-based method for characterizing objectsgiven the tracked regions, and a ML (Maximum Likelihood)blob-tracking process given the object characterizationand the previous blob sequence. The proposed incremental2DPCA updates the row- and column-projected covariancematrices recursively, and is computationally more efficient for online learning of dynamic objects. The proposed ML blobtracking takes into account both the shape information and object characteristics. Tests and evaluations were performed on indoor and outdoor image sequences containing a range of moving objects in dynamic backgrounds, which have shown good tracking results. Comparisons with the method using the conventional PCA were also made

FPGA Implementation of a Fixed Latency Scheme in a Signal Packet Router for the Upgrade of ATLAS Forward Muon Trigger Electronics

We propose a new fixed latency scheme for Xilinx gigabit transceivers that will be used in the upgrade of the ATLAS forward muon spectrometer at the Large Hadron Collider. The fixed latency scheme is implemented in a 4.8 Gbps link between a frontend data serializer ASIC and a packet router. To achieve fixed latency, we use IO delay and dedicated carry in resources in a Xilinx FPGA, while minimally relying on the embedded features of the FPGA transceivers. The scheme is protocol independent and can be adapted to FPGA from other vendors with similar resources. This paper presents a detailed implementation of the fixed latency scheme, as well as simulations of the real environment in the ATLAS forward muon region.Comment: 8 pages, 8 figures, accepted by IEEE - Transactions on Nuclear Scienc

Functional conductive nanomaterials via polymerisation in nano-channels: PEDOT in a MOF.

Reactions inside the pores of metal-organic frameworks (MOFs) offer potential for controlling polymer structures with regularity to sub-nanometre scales. We report a wet-chemistry route to poly-3,4-ethylenedioxythiophene (PEDOT)-MOF composites. After a two-step removal of the MOF template we obtain unique and stable macroscale structures of this conductive polymer with some nanoscale regularity.The project is funded through the European Research Council (ERC) grant (grant number: EMATTER 280078). AKC thanks the Ras Al Khaimah Center for Advanced Materials (RAK-CAM). JDWM and MF acknowledge funding through a Discovery Grant from The Natural Sciences and Engineering Research Council of Canada (NSERC). TW thanks the China Scholarship Council (CSC) for funding and the Engineering and Physical Sciences Research Council of the UK (EPSRC) Centre for Doctoral Training in Sensor Technologies and Applications (grant number: EP/L015889/1) for support. SH acknowledges the Alexander von Humboldt Foundation for funding. SS is funded through a scholarship from the Cambridge Overseas Trust. JSB thanks the Isaac Newton Trust for financial support for the FEI Tecnait TEM. The authors would also like to show the gratitude to Phenom-World for the use of the Phenom Pro X SEM and Dr Suman-Lata Sahonta for the help with Raman spectroscopy.This is the final version of the article. It first appeared from the Royal Society of Chemistry at http://dx.doi.org/10.1039/c6mh00230g

Electroactive polymers for sensing.

Electromechanical coupling in electroactive polymers (EAPs) has been widely applied for actuation and is also being increasingly investigated for sensing chemical and mechanical stimuli. EAPs are a unique class of materials, with low-moduli high-strain capabilities and the ability to conform to surfaces of different shapes. These features make them attractive for applications such as wearable sensors and interfacing with soft tissues. Here, we review the major types of EAPs and their sensing mechanisms. These are divided into two classes depending on the main type of charge carrier: ionic EAPs (such as conducting polymers and ionic polymer-metal composites) and electronic EAPs (such as dielectric elastomers, liquid-crystal polymers and piezoelectric polymers). This review is intended to serve as an introduction to the mechanisms of these materials and as a first step in material selection for both researchers and designers of flexible/bendable devices, biocompatible sensors or even robotic tactile sensing units.This is the final version of the article. It first appeared from The Royal Society Publishing via https://doi.org/10.1098/rsfs.2016.002