General study on piezoelectric transformer

Author name used in this publication: Cheng K. W. E.Author name used in this publication: Kwok K. W.Power Electronics Research Center, Department of Electrical EngineeringAuthor name used in this publication: Chan H.Refereed conference paper2004-2005 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

Modeling and analysis of piezoelectric transformer using multi-mesh loop matrix circuit under square-wave excitation conditions

K. W. Kwok, X. X. Wang and H. Chan, Department of Applied PhysicsAuthor name used in this publication: K. W. E. ChengAuthor name used in this publication: S. L. HoAuthor name used in this publication: K. W. KwokAuthor name used in this publication: H. ChanAuthor name used in this publication: X. D. XueRefereed conference paper2005-2006 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

Observation of CR Anisotropy with ARGO-YBJ

The measurement of the anisotropies of cosmic ray arrival direction provides important informations on the propagation mechanisms and on the identification of their sources. In this paper we report the observation of anisotropy regions at different angular scales. In particular, the observation of a possible anisotropy on scales between $\sim$ 10 $^{\circ}$ and $\sim$ 30 $^{\circ}$ suggests the presence of unknown features of the magnetic fields the charged cosmic rays propagate through, as well as potential contributions of nearby sources to the total flux of cosmic rays. Evidence of new weaker few-degree excesses throughout the sky region $195^{\circ}\leq$ R.A. $\leq 315^{\circ}$ is reported for the first time.Comment: Talk given at 12th TAUP Conference 2011, 5-9 September 2011, Munich, German

Development of cordycepin formulations for preclinical and clinical studies

There is extensive literature on in vivo studies with cordycepin but these studies were generally conducted without validation of the various formulations, especially in terms of the solubility of cordycepin in the dosing vehicles used. Cordycepin is a promising drug candidate in multiple therapeutic areas and there is a growing interest in studies aimed at assessing the pharmacological activity of this compound in relevant animal disease models. It is likely that many reported in vivo studies used formulations in which cordycepin was incompletely soluble. This can potentially confound the interpretation of pharmacokinetics and efficacy results. Furthermore, the presence of particles in intravenously administered suspension can cause adverse effects and should be avoided. Here we present the results from our development of simple and readily applicable formulations of cordycepin based on quantitative solubility assessment. Homogeneous solutions of cordycepin were prepared in phosphate-buffered saline (PBS) at different pH levels, suitable as formulations for both intravenously and oral administration. For the purpose of high-dose oral administration we also developed propylene glycol (PPG)-based vehicles in which cordycepin is completely soluble. The stability of the newly developed formulations was also assessed, as well the feasibility of their sterilisation by filtration. Additionally, an HPLC-UV method for the determination of cordycepin in the formulations, which may also be useful for other purposes, was developed and validated. Our study could provide useful information for improvement of future preclinical and clinical studies involving cordycepin

Direct comparison of methionine restriction with leucine restriction on the metabolic health of C57BL/6J mice

EKL was the recipient of a BBSRC postgraduate studentship. This work was funded by Tenovus Scotland project grant to MD and NM (G13/07) and BBSRC DTG. MD is also supported by the British Heart Foundation (PG/09/048/27675, PG/11/8/28703 and PG/14/43/30889) and Diabetes UK (14/0004853). NM is funded by British Heart Foundation (PG/16/90/32518).Peer reviewedPublisher PD

Synthesis and Characterization of Monodispersed Copper Colloids in Polar Solvents

A chemical reduction method for preparing monodispersed pure-phase copper colloids in water and ethylene glycol has been reported. Owing to the reduction property of ethylene glycol, the reaction rate in ethylene glycol is higher than that in water. In addition, the amount of reducing agent can be reduced largely. Ascorbic acid plays roles as reducing agent and antioxidant of colloidal copper, due to its ability to scavenge free radicals and reactive oxygen molecules. Thermogravimetric results reveal that the as-prepared copper nanoparticles have good stability, and they begin to be oxidized at above 210 °C. Polyvinyl pyrrolidone works both as size controller and polymeric capping agents, because it hinders the nuclei from aggregation through the polar groups, which strongly absorb the copper particles on the surface with coordination bonds

Targeting colorectal cancer stem cells with inducible caspase-9

Colorectal cancer stem cells (CSCs) drive tumor growth and are suggested to initiate distant metastases. Moreover, colon CSCs are reportedly more resistant to conventional chemotherapy, which is in part due to upregulation of anti-apoptotic Bcl-2 family members. To determine whether we could circumvent this apoptotic blockade, we made use of an inducible active caspase-9 (iCasp9) construct to target CSCs. Dimerization of iCasp9 with AP20187 in HCT116 colorectal cancer cells resulted in massive and rapid induction of apoptosis. In contrast to fluorouracil (5-FU)-induced apoptosis, iCasp9-induced apoptosis was independent of the mitochondrial pathway as evidenced by Bax/Bak double deficient HCT116 cells. Dimerizer treatment of colon CSCs transduced with iCasp9 (CSC-iCasp9) also rapidly induced high levels of apoptosis, while these cells were unresponsive to 5-FU in vitro. More importantly, injection of the dimerizer into mice that developed a colon CSC-iCasp9-induced tumor resulted in a strong decrease in tumor size, an increase in tumor cell apoptosis and a clear loss of CD133+ CSCs. Taken together, our data indicate that dimerization of iCasp9 circumvents the apoptosis block in CSCs, which results in effective tumor regression in vivo

Activated macrophages promote Wnt signalling through tumour necrosis factor-α in gastric tumour cells

The activation of Wnt/β-catenin signalling has an important function in gastrointestinal tumorigenesis. It has been suggested that the promotion of Wnt/β-catenin activity beyond the threshold is important for carcinogenesis. We herein investigated the role of macrophages in the promotion of Wnt/β-catenin activity in gastric tumorigenesis. We found β-catenin nuclear accumulation in macrophage-infiltrated dysplastic mucosa of the K19-Wnt1 mouse stomach. Moreover, macrophage depletion in ApcΔ716 mice resulted in the suppression of intestinal tumorigenesis. These results suggested the role of macrophages in the activation of Wnt/β-catenin signalling, which thus leads to tumour development. Importantly, the conditioned medium of activated macrophages promoted Wnt/β-catenin signalling in gastric cancer cells, which was suppressed by the inhibition of tumour necrosis factor (TNF)-α. Furthermore, treatment with TNF-α induced glycogen synthase kinase 3β (GSK3β) phosphorylation, which resulted in the stabilization of β-catenin. We also found that Helicobacter infection in the K19-Wnt1 mouse stomach caused mucosal macrophage infiltration and nuclear β-catenin accumulation. These results suggest that macrophage-derived TNF-α promotes Wnt/β-catenin signalling through inhibition of GSK3β, which may contribute to tumour development in the gastric mucosa