Lead-Free Piezoelectric Transducers for Microelectronic Wirebonding Applications

Author name used in this publication: K. W. KwokAuthor name used in this publication: S. H. ChoyAuthor name used in this publication: H. L. W. Chan2010-2011 > Academic research: refereed > Chapter in an edited book (author)published_fina

Electrorotation of colloidal suspensions

When a strong electric field is applied to a colloidal suspension, it may cause an aggregation of the suspended particles in response to the field. In the case of a rotating field, the electrorotation (ER) spectrum can be modified further due to the local field effects arising from the many-particle system. To capture the local field effect, we invoke the Maxwell-Garnett approximation for the dielectric response. The hydrodynamic interactions between the suspended particles can also modify the spin friction, which is a key to determine the angular velocity of ER. By invoking the spectral representation approach, we derive the analytic expressions for the characteristic frequency at which the maximum angular velocity of ER occurs. From the numerical caculation, we find that there exist two sub-dispersions in the ER spectrum. However, the two characteristic frequencies are so close that the two peaks actually overlap and become a single broad peak. We report a detailed investigation of the dependence of the characteristic frequency and the dispersion strength of ER on various material parameters.Comment: RevTeX, 4 eps figures; clarifying discussion added in accord with referees' reports; accepted by Physics Letters

Nonlinear ER effects in an ac applied field

The electric field used in most electrorheological (ER) experiments is usually quite high, and nonlinear ER effects have been theoretically predicted and experimentally measured recently. A direct method of measuring the nonlinear ER effects is to examine the frequency dependence of the same effects. For a sinusoidal applied field, we calculate the ac response which generally includes higher harmonics. In is work, we develop a multiple image formula, and calculate the total dipole moments of a pair of dielectric spheres, embedded in a nonlinear host. The higher harmonics due to the nonlinearity are calculated systematically.Comment: Presented at Conference on Computational Physics (CCP2000), held at Gold Coast, Australia from 3-8, December 200

Dielectric properties and relaxation of SrBi2(Nb0.25Ta0.75)2O9 ceramic at RF frequency

The dielectric properties and relaxation of the SrBi2(Nb0.25Ta0.75)2O9 ceramic were investigated from 3 to 300 MHz using frequency domain measurement by an impedance spectroscopy. Our results show that the dielectric relaxation of the ceramic can be understood in terms of power law dependence known as the Curie-von Schweidler law. It is assumed that defects, Schottkey jumps of electrons between localized states and the motions of ions play an important role in the dielectric properties and relaxation of the ceramic. The ceramic has large relative permittivity (*er ~117 at 300 MHz), low dielectric loss (tan*de < 0.018 at 300 MHz) and small dispersion ( < 3% decrease in *er from 3 to 300 MHz). The Curie temperature of the ceramic is very high (~370 DGC), implying that it has a small temperature coefficient. Hence the SrBi2(Nb0.25Ta0.75)2O9 ceramic is a potential candidate for microwave applications

A multi-modal intervention for managing the fatigue–sleep disturbance–depressed mood symptom cluster in breast cancer patients undergoing chemotherapy: A pilot study

Objective: To examine the feasibility and acceptability of a multi-modal intervention for managing the cancer-related fatigue–sleep disturbance–depressed mood (F-S-D) symptom cluster in patients with breast cancer (BC) and receiving chemotherapy in Hong Kong, and the preliminary effects of such intervention on the occurrence of the F-S-D symptom cluster in these patients. Methods: This study was a single-blind randomized controlled trial. Patients with BC scheduled for chemotherapy were recruited. Intervention participants received a weekly nurse-led multi-modal intervention lasting 7 weeks. The feasibility parameters and adverse events were assessed using logbook records. Acceptability was evaluated using a program evaluation questionnaire. F-S-D symptoms and quality of life (QOL) were measured at baseline (T0), upon intervention completion (T1), and 3 months after intervention completion (T2). Generalized estimating equation analyses were used. Results: Fifty participants were enrolled. The eligibility and enrollment rates were 11% and 87.7%, respectively. The rate of adherence to the intervention was 96%. No adverse events were reported. All participants were satisfied with the intervention, which had significant effects in terms of reducing the occurrence of the F-S-D symptom cluster at T2 (P ​= ​0.035) and improving QOL at T1 and T2 (T1: P ​= ​0.035; T2: P ​= ​0.012). Conclusions: The multi-modal intervention is a feasible, acceptable, and safe intervention that demonstrated preliminary positive effects in managing the F-S-D symptom cluster and improving QOL in patients with BC and receiving chemotherapy in Hong Kong. This study provides key insights into F-S-D symptom cluster management in patients with BC. Trial registration: ChiCTR2100047819 (Chinese Clinical Trial Register)