Photoluminescence, electro-optic response and piezoelectric properties in pressureless-sintered Er-doped KNN-based transparent ceramics

Er-doped (K0.5Na0.5)1−xLixNb1−xBixO3 (0.05 ≤ x ≤ 0.08) ceramics have been prepared by pressureless sintering. Because of the cubic-like phase as well as the dense and fine-grained structure, the ceramics are optically clear, exhibiting high transmittances in the near-infrared and mid-infrared (MIR) regions (∼50% and ∼75%, respectively). They also possess strong electro-optic (EO) response, giving a large effective linear EO coefficient (128–184 pm/V). Owing to Er3+, the ceramics exhibit green and red up-conversion photoluminescence (PL) emissions, which are sensitive to the crystal symmetry of the ceramic host. The ceramics also exhibit a low absorption coefficient of OH− groups and then distinct and broadband MIR emissions. Together with the relatively large piezoelectric coefficient (70–90 pC/N), high dielectric constant (∼1400) and low dielectric loss (∼0.03), the ceramics open up potential applications in electrical/optical interdisciplinary field, such as visible displays, MIR solid lasers and optical attenuators.Department of Applied Physic

CFD simulation of flow in a long street canyon under a perpendicular wind direction : evaluation of three computational settings

A street canyon is an important platform for the understanding of local atmospheric flow and other related processes in the built environment. Many previous studies focused on long street canyons under a perpendicular wind direction, as they represent the worst street canyon microclimate, such as stagnation of wind and accumulation of pollutants. While CFD simulations were widely applied to investigate atmospheric processes in street canyons, appropriate computational settings are important factors influencing the predictive reliability. A non-exhaustive literature review of CFD studies on atmospheric processes in long street canyons indicates an arbitrary selection of three important computational settings, namely computational domain configuration, domain dimensions and inflow boundary conditions. Based on previous water tunnel experimental data for street canyons with aspect ratio equal to 0.5, 1.0 and 2.0, this study evaluates the influence of the three computational settings on CFD prediction of isothermal flow field inside the street canyons. Flow field inside an urban street canyon cannot be reasonably predicted using an isolated street canyon included in a conventional computational domain, which, however, can be well predicted using a T-shape computational domain where a street canyon is connected to a free flow layer above the canyon. A T-shape domain with the upstream length, downstream length and height above a street canyon all equal to the height of the street canyon is appropriate when considering both computational cost and predictive accuracy. It is reasonable to use uniform inflow boundary conditions to represent the free layer above street canyons.Department of Building Services Engineerin

Improving the selection and development of influenza vaccine viruses – Report of a WHO informal consultation on improving influenza vaccine virus selection, Hong Kong SAR, China, 18–20 November 2015

Since 2010 the WHO has held a series of informal consultations to explore ways of improving the currently highly complex and time-pressured influenza vaccine virus selection and development process. In November 2015 experts from around the world met to review the current status of efforts in this field. Discussion topics included strengthening influenza surveillance activities to increase the availability of candidate vaccine viruses and improve the extent, timeliness and quality of surveillance data. Consideration was also given to the development and potential application of newer laboratory assays to better characterize candidate vaccine viruses, the potential importance of antibodies directed against influenza virus neuraminidase, and the role of vaccine effectiveness studies. Advances in next generation sequencing and whole genome sequencing of influenza viruses were also discussed, along with associated developments in synthetic genomics technologies, evolutionary analysis and predictive mathematical modelling. Discussions were also held on the late emergence of an antigenic variant influenza A(H3N2) virus in mid-2014 that could not be incorporated in time into the 2014–15 northern hemisphere vaccine. There was broad recognition that given the current highly constrained influenza vaccine development and production timeline it would remain impossible to incorporate any variant virus which emerged significantly long after the relevant WHO biannual influenza vaccine composition meetings. Discussions were also held on the development of pandemic and broadly protective vaccines, and on associated regulatory and manufacturing requirements and constraints. With increasing awareness of the health and economic burdens caused by seasonal influenza, the ever-present threat posed by zoonotic influenza viruses, and the significant impact of the 2014–15 northern hemisphere seasonal influenza vaccine mismatch, this consultation provided a very timely opportunity to share developments and exchange views. In all areas, a renewed and strengthened emphasis was placed on developing concrete and measurable actions and identifying the key stakeholders responsible for their implementation.Department of Applied Biology and Chemical Technolog

Discovery of novel rivastigmine-hydroxycinnamic acid hybrids as multi-targeted agents for Alzheimer's disease

A series of rivastigmine-caffeic acid and rivastigmine-ferulic acid hybrids were designed, synthesized, and evaluated as multifunctional agents for Alzheimer's disease (AD) in vitro. The new compounds exerted antioxidant neuroprotective properties and good cholinesterases (ChE) inhibitory activities. Some of them also inhibited amyloid protein (A beta) aggregation. In particular, compound 5 emerged as promising drug candidates endowed with neuroprotective potential, ChE inhibitory, A beta self-aggregation inhibitory and copper chelation properties. These data suggest that compound 5 offers an attractive starting point for further lead optimization in the drug-discovery process against AD.Department of Applied Biology and Chemical Technolog

Cu2ZnSnS4/MoS2-reduced graphene oxide heterostructure : nanoscale interfacial contact and enhanced photocatalytic hydrogen generation

Hydrogen generation from water using noble metal-free photocatalysts presents a promising platform for renewable and sustainable energy. Copper-based chalcogenides of earth-abundant elements, especially Cu 2 ZnSnS 4 (CZTS), have recently arisen as a low-cost and environment-friendly material for photovoltaics and photocatalysis. Herein, we report a new heterostructure consisting of CZTS nanoparticles anchored onto a MoS 2 -reduced graphene oxide (rGO) hybrid. Using a facile two-step method, CZTS nanoparticles were in situ grown on the surface of MoS 2 -rGO hybrid, which generated high density of nanoscale interfacial contact between CZTS and MoS 2 -rGO hybrid. The photoexcited electrons of CZTS can be readily transported to MoS 2 through rGO backbone, reducing the electron-hole pair recombination. In photocatalytic hydrogen generation under visible light irradiation, the presence of MoS 2 -rGO hybrids enhanced the hydrogen production rate of CZTS by 320%, which can be attributed to the synergetic effect of increased charge separation by rGO and more catalytically active sites from MoS 2. Furthermore, this CZTS/MoS 2 -rGO heterostructure showed much higher photocatalytic activity than both Au and Pt nanoparticle-decorated CZTS (Au/CZTS and Pt/CZTS) photocatalysts, indicating the MoS 2 -rGO hybrid is a better co-catalyst for photocatalytic hydrogen generation than the precious metal. The CZTS/MoS 2 -rGO system also demonstrated stable photocatalytic activity for a continuous 20 h reaction.Department of Applied Biology and Chemical Technolog

Optimal power sharing control of wind turbines

Wind generation can significantly disturb the power balance within particularly a weak power grid such as stand-alone microgrids. To counterbalance the impacts, an optimal power sharing control scheme that seeks to cope with the power dispatching demand by system operator is proposed for DFIG wind turbines. The control scheme can fulfill the dispatching command via maximizing the rotational kinetic energy stored in DFIGs, which can be later released for system support when needed.Department of Electrical Engineerin

Zero-valent iron for the abatement of arsenate and selenate from flowback water of hydraulic fracturing

Zero-valent iron (ZVI) was tested for the removal of 150 mu g L-1 As(V) and 350 mu g L-1 Se(VI) in high salinity (ionic strength 0.35-4.10 M) flowback water of hydraulic fracturing. Over 90% As(V) and Se(VI) was removed by 2.5 g L-1 ZVI in Day-14 flowback water up to 96-h reaction, with the remaining concentration below the maximum contaminant level for As(V) and criterion continuous concentration for Se(VI) recommended by US EPA. The kinetics of As(V) and Se(VI) removal followed a pseudo-second order rate expression with the observed rates of 4.51 x 10(-2)-4.91 x 10(-1) and 3.48 x 10(-2)-6.58 x 10(-1) h(-1) (with 0.5-10 g L-1 ZVI), respectively. The results showed that Se(VI) removal significantly decreased with increasing ionic strength, while As(V) removal showed little variation. Common competing anions (nitrate, bicarbonate, silicate, and phosphate), present in shallow groundwater and stormwater, caused marginal Se(VI) desorption (2.42 +/- 0.13%) and undetectable As(V) desorption from ZVI. The competition between As(V) and Se(VI) for ZVI removal depended on the initial molar ratio and surface sites, which occurred when the Se(VI) concentration was higher than the As(V) concentration in this study. The characterization of As(V)- and Se(VI)-loaded ZVI by X-ray diffraction and Raman analysis revealed that ZVI gradually converted to magnetite/maghemite corrosion products with lepidocrocite in flowback water over 30 days. Similar corrosion compositions were confirmed in, aerobic and anaerobic conditions regardless of the molar ratio of As(V) to Se(VI). The high reactivity and stability of ZVI showed its suitability for in-situ prevention of As(V) and Se(VI) migration due to accidental leakage, spillage, or overflow of flowback water.Department of Civil and Environmental Engineerin

Pulsed electromagnetic field at different stages of knee osteoarthritis in rats induced by low-dose monosodium iodoacetate : effect on subchondral trabecular bone microarchitecture and cartilage degradation

The aim of the study was to investigate the efficacy of pre-emptive, early, and delayed pulsed electromagnetic field (PEMF) treatment on cartilage and subchondral trabecular bone in knee osteoarthritis (OA) rats induced by low-dose monosodium iodoacetate (MIA). Seventy-five 12-week-old male Sprague–Dawley rats were assigned to five groups: OA (n = 30), pre-emptive PEMF (n = 10), early PEMF (n = 10), delayed PEMF (n = 10), and control (n = 15). Osteoarthritis was induced by injecting 0.2 mg MIA in rat's right knee joint. Control rats received a single sterile saline injection in the right knee. Male rats received pre-emptive (n = 10, day 0-end of week 4), early (n = 10, end of week 4-end of week 8), or delayed (n = 10, end of week 8-end of week 12) PEMF treatment (75 Hz, 1.6 mT). After 4, 8, and 12 weeks, rats were sacrificed at each time point and right knees were harvested. After sacrifice, micro-computed tomography, histology, and biomarker analyses were performed. We found pre-emptive PEMF treatment preserved subchondral trabecular bone microarchitecture and prevented subchondral bone loss in MIA-induced OA rat model. Early and delayed PEMF treatment maintained subchondral trabeculae. PEMF treatment increased bone and cartilage formation, and decreased bone and cartilage resorption. Pre-emptive and early PEMF treatment had moderate effects on cartilage degradation. Time point of treatment initiation is crucial for treating OA. PEMF might become a potential biophysical treatment modality for osteoarthritis. Bioelectromagnetics. 38:227–238, 2017.Chinese Mainland Affairs Offic

Utopia and its otherwise : revolutionary youthfulness, lyricism, and alternative quests for the "East" in Kundera's Life is Elsewhere

School of Professional Education and Executive Developmen

Influenza vaccination in older people with diabetes and their household contacts

Background People with diabetes are at a higher risk of influenza infections and severe complications. The vaccination of close contacts could offer indirect protection to people with diabetes; this is known as “herd immunity.” The aim of this study is to investigate the vaccination rates of people with diabetes and their household contacts in Hong Kong.Research design and methods Face-to-face interviews with 158 patients diagnosed with Type 2 diabetes and aged ⩾65 years were conducted in clinics. Telephone interviews were then conducted with 281 adult household contacts.Results Seasonal influenza vaccination rates were 54.5% and 27.4%, in people with diabetes and their contacts, respectively. The vaccination status of patients was not significantly associated with the vaccination of their household contacts (p = 0.073). Among household contacts, children or the elderly, the partners or couples of patients, and those with more hours of daily contact, or with chronic conditions, were associated with higher vaccination rates. However, only age remained significant after adjusting for confounding factors in logistic regression models.Conclusions The low vaccination rates of people with diabetes and their close contacts highlight the need to promote vaccination in susceptible populations and to educate the public about herd immunity.School of NursingSchool of Optometr