There is an urgent need for engineered materials to improve outcomes within medicine. The electrostatic drawing of fibres, or electrospinning, is one such technology that produces new forms of materials for use within tissue engineering. As with many new technologies, electrospinning promised to revolutionize the fields of tissue engineering and textiles in particular. After initially generating an exponentially increasing number of scientific publications over the past decade, enthusiasm for electrospinning has been tempered somewhat by the “underwhelming nature” of the first products. However, there are still many reasons why electrospinning is an important process that will shape tissue engineering in the 21st century. Electrospinning is inexpensive, can be applied to many different polymers and contains diverse aspects that are only now being researched - new electrospinning products are being described in the literature daily. Electrospun fibres are formed by applying a high voltage between a polymeric liquid and a collection target. One major application of electrospinning is to make nano-scale fibres to mimic the extracellular matrix or to produce a scaffold for tissue engineering. Where a cell may adhere to only one micro-fibre in a conventional scaffold, one cell can adhere to multiple electrospun nanofibres. The fibres can guide migration, allow proliferation and even differentiate cells. This talk describes the technique of electrospinning, focussing on surface engineering the fibres for specific interaction in vitro. Additionally the automation of the electrospinning process is introduced and how this allows a new generation of complex biomedical materials to be produced.

Driven by the pharmaceutical industry to realise the full potential of the lungs for local and systemic treatment of diseases, pulmonary drug delivery by inhalation aerosols has been undergoing significant development in the past two decades. This has led to novel research of aerosol delivery devices coupled to the formulations and new technologies which are required to produce particles of defined characteristics for improved delivery. This lecture highlights some of the key findings and recent advances in this rapidly expanding field, with examples of clinical applications.

Cough airflow dynamics have been previously studied using a variety of experimental methods. In this study, real-time, non-invasive shadowgraph imaging was applied to obtain additional analyses of cough airflows produced by healthy volunteers. A wide variation in both propagation distance and peak velocities were seen among the volunteers of both sexes, which was not unexpected. Of interest was the rapid decrease in the velocity of the cough aerosols as they encountered the ambient air. Despite some limitations of the shadowgraph imaging approach, the peak exit velocities compare favorably with those reported previously using other methods.

Ultraviolet radiation (UV) (290-400 nm) plays an important role for atmospheric chemistry and photochemistry, human health, and it also plays a vital role for the formation and destruction of ozone in the atmosphere. An increase in UV can accelerate the chemical and photochemical reactions in the troposphere, lead to high O3 production, especially industrial cities in summer. Then, it is important to study UV and its affecting factors, as well as UV long-term trends, especially for the Beijing megacity. Analyzing observational data for solar radiation, meteorological parameters and total ozone concentration from January 1990 to December 1991 in Beijing enabled the development of an empirical method for estimation of UV irradiance (UVI) in clear skies. Predicted values from the model agreed with observations. The mean relative bias for 24 months was 1.9%. UVI in clear skies from 1979 to 1998 was calculated, and its long-term variation showed a declining trend of -3.89%, which was accompanied by a decrease in total O3 of -5.75%, a decrease in scattering factor (S/D, the ratio of solar scattered to direct radiation) of -20.79%, and an increase in water vapor content of +4.76%. A minor but interesting phenomenon was found for UVI variation in summer. It is hypothesized that many substances in the atmosphere, including volatile organic compounds (VOCs) and their oxidation products (including secondary organic compounds, SOA), very fine particles and others absorb and/or utilize UV energy. The long-term UVI trends and its main controlling factors in four seasons during the previous 2 decades are discussed, UV energy consumption by atmospheric chemical and photochemical processes is especially important during summer. The minor but important phenomenon of UVI decrease in summer enlarges the effect of stronger UV absorption and utilization by gases, liquids, particles (GLPs) through OH radicals. Therefore, the measurements in the laboratory and field are needed, including UV absorption and utilization parameters of GLPs, then, new data and mechanisms should be introduced into the models, so as to improve our understanding and forecasting of UV radiation.

This talk addresses the optimal control problems for linear systems with respect to different Bolza-Meyer criteria, where 1) the integral control and state energy terms are quadratic and the non-integral term is of the first degree or 2) the control energy term is quadratic and the state energy terms are of the first degree. The optimal solutions are obtained as sliding mode-like control laws, whereas the conventional linear feedback control fails to provide a causal solution. Performance of the obtained regulators is verified in the illustrative example against the conventional LQ regulator that is optimal for the quadratic Bolza-Meyer criterion. The simulation results confirm an advantage in favor of the designed sliding mode regulators.

Over the past few years our work has focused on exploring fundamental deformation processes in Ti and its alloys. The work has two main strands: (i) extraction of single crystal mechanical properties, and (ii) characterising local stress and lattice rotation fields that develop during deformation. We have developed methods to extract single crystal elastic constants, and critical resolved shear stresses from polycrystalline samples. FIB is used to machine micro-cantilevers and/or micro-pillars within individual selected grains offering suitable orientations, and these are tested in bending or compression with a nanoindenter. For plastic deformation significant size effects are evident but we are able to extrapolate the data to bulk values. Data will be presented for Ti (?), Ti-6Al (?) and Ti-6Al-4V (???), and comparison made between different slip systems. We have also been using the high resolution EBSD method, developed in the group, to map local lattice rotations and elastic strain variations in deformed Ti alloys. The lattice curvatures (and elastic strain gradients) can be used to determine a lower bound estimate of the geometrically necessary dislocation density which allows the accumulation of dislocations within a microstructure to be studied. The presentation will include application of the method to studying indents in single grains of Ti, the interaction of slip bands and twins with grain boundaries, and mapping of dislocation content in Ti-6Al-4V polycrystals deformed by rolling, tension and fatigue.

Diseases or congenital malformations of the human urinary tract might benefit from regenerative efforts by tissue engineering. The basics of urinary tract cells culturing, and in particular the development of a functional multilayered urothelial construct are discussed. The development of flat and tubular compressed collagen structures and their physical behavior in-vitro are presented. The functionality of tubular urethral structures is demonstrated in a rabbit model. Further compressed urinary tract cell-loaded collagen-polymer hybrid structures, studied in-vitro and in-vivo in a rodent model, are demonstrated. In addition to collagen, fibrin is discussed as a cell-carrier. The development of a novel advantageous engineered fibrin to which TG-aprotinin or KPI can be covalently bound to prevent early degradation is discussed. Also the technology of binding of IGF 1 to fibrin to promote smooth muscle growth is demonstrated and in-vivo results in a rat model are discussed. Early results in cell sorting by molecular beacons and their potential as marker of progenitor cells are presented.

New theory has been developed for describing plastic deformation over wide ranges of temperature and strain rate. The new formulation takes Kocks-Mecking approach as a starting point, and employing a single formulation is able to describe plasticity from cryogenic to near-melting temperatures, both for FCC and BCC metals. The theory does not fit the activation energy for dislocation annihilation, but instead provides a mathematical formulation to compute it in terms of the dislocation formation and migration energy, as well as its statistical entropy. The theory employs as input only physical parameters intrinsic to the material: shear modulus, yield stress, vacancy self-diffusion energy and the stacking fault energy. The formulation has been able to predict the saturation stress, stress-strain curves, dislocation cell size and misorientation angle for several pure metals. The work is currently being extended to binary and ternary systems to design new high-temperature alloys which will be produced in the context of the Accelerated Metallurgy project, which will produce and characterise a high-rate throughput of new (unknown) alloy systems.

Abstract: Prof. Wong has research areas in heat transfer, air conditioning and refrigeration, and energy conservation. He has many inventions that are related to these research areas. In this seminar, he will give a talk in two of his prize winning innovations. The first is a multiple-function energy-saving air conditioner, and the second is an auto-control energy-saving smart clothes dryer. The rationales and operation principles of these two innovations will be introduced during the seminar. He will also share his experience of how to become a successful inventor in energy related products.

Refer to Web link.