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Hong Kong, Hong Kong

Chan J.Y.-Y.,Hong Kong Polytechnic University | Chan E.,Hong Kong Polytechnic University | Chan S.-W.,Hong Kong Polytechnic University | Chan S.-W.,State Key Laboratory of Chinese Medicine and Molecular Pharmacology | And 7 more authors.
Pharmaceutical Biology

Context: Grifola frondosa (Polyporaceae), maitake, is a widely consumed edible mushroom in some Asian countries. The fruit bodies and mycelia of maitake have shown different bioactive compounds with anticancer and other therapeutic properties. Objective: This study evaluated three chemically modified maitake polysaccharide-peptides' (MPSP) adjuvant effect (in vivo) and anticancer activity (in vitro growth inhibitory effect) compared with crude MPSP from G. frondosa. Materials and methods: We investigated the possibility of enhancing the adjuvant effect and anticancer effect of crude MPSP by using simple chemical modification methods to convert crude MPSP to phosphorylated, acetylated or esterified MPSPs. The adjuvant effect and growth inhibitory effect were evaluated by C6 cell inoculated rat model with cyclophosphamide (CPA) treatment and in vitro cell viability assay, respectively. Results: All four tested MPSPs showed significant adjuvant effect to CPA treatment on rats inoculated with C6 cancer cells. In addition, an obvious growth inhibitory effect was observed in C6 cancer cells but not in normal brain cells treated with various forms of MPSPs. Only phosphorylation could significantly (p<0.05) improve the adjuvant effect (in vivo) and growth inhibitory effect. A same rank order (phosphorylated MPSP > esterified MPSP ≥ acetylated MPSP ≥ crude MPSP) of efficacy was observed in both the in vivo and in vitro assays. Discussion and conclusion: This study showed chemical phosphorylation could markedly enhance both adjuvant effects and growth inhibitory effects. This study demonstrated the feasibility of enhancing the efficacy of MPSP by using a simple chemical modification method, and this provides a foundation for future study in this area. © 2011 Informa Healthcare USA, Inc. Source

Ching C.T.-S.,National Chi Nan University | Ching C.T.-S.,Asia University, Taiwan | Yong K.-K.,Puli Christian Hospital | Yao Y.-D.,Hong Kong Community College | And 6 more authors.
International Journal of Nanomedicine

The aims of this study were to investigate the most effective combination of physical forces from laser, electroporation, and reverse iontophoresis for noninvasive transdermal extraction of uric acid, and to develop a highly sensitive uric acid biosensor (UAB) for quantifying the uric acid extracted. It is believed that the combination of these physical forces has additional benefits for extraction of molecules other than uric acid from human skin. A diffusion cell with porcine skin was used to investigate the most effective combination of these physical forces. UABs coated with ZnO2 nanoparticles and constructed in an array configuration were developed in this study. The results showed that a combination of laser (0.7 W), electroporation (100 V/cm2), and reverse iontophoresis (0.5 mA/cm2) was the most effective and significantly enhanced transdermal extraction of uric acid. A custom-designed UAB coated with ZnO2nanoparticles and constructed in a 1×3 array configuration (UAB-1×3-ZnO2) demonstrated enough sensitivity (9.4 μA/mM) for quantifying uric acid extracted by the combined physical forces of laser, electroporation, and RI. A good linear relationship (R2=0.894) was demonstrated to exist between the concentration of uric acid (0.2-0.8 mM) inside the diffusion cell and the current response of the UAB-1×3-ZnO2. In conclusion, a new approach to noninvasive transdermal extraction and quantification of uric acid has been established. © 2014 Ching et al. Source

Chen Q.,Hong Kong Polytechnic University | Hu Z.,Hong Kong Polytechnic University | Hu Z.,South China Agricultural University | Yao F.Y.D.,Hong Kong Community College | Liang H.,Hong Kong Polytechnic University
LWT - Food Science and Technology

Pomelo peels were first processed by a solvent-free microwave extraction (SFME) for essential oils, then by a hot-solvent microwave extraction (HSME) for pectin. SFME was superior to the conventional hydrodistillation (HD) method for essential oil extraction and HSME was better than acidic solution method for pectin extraction in terms of extraction efficiency and yield of targeted component. Chemical composition analysis by GC-MS showed that SFME did not affect the quality of essential oils. By using the response surface methodology, the optimal conditions of HSME for pectin was found at microwave power of 520 W, solvent pH value of 1.5 and extraction time of 5.6 min. Surface view by optical microscope (OM) and cross sectional view by scanning electron microscope (SEM) of the peels suggested that microwave can enhance the extraction process by two distinct mechanisms: one attributes to the diffusion across the intact oil gland while the other involves the convection through the broken oil gland. © 2015 Elsevier Ltd. Source

Yu F.W.,Hong Kong Community College | Chan K.T.,Hong Kong Polytechnic University
5th Asian Conference on Refrigeration and Air Conditioning, ACRA 2010 - Green Breeze from Asia: Frontiers of Refrigerants, Heat Transfer and System

This study investigates how the environmental performance of water-cooled chiller systems can be optimized by applying load-based speed control to all the system components. New chiller and cooling tower models were developed using a transient systems simulation program called TRNSYS 15 in order to assess the electricity and water consumption of a chiller plant operating for a building cooling load profile. The chiller model was calibrated using manufacturer's performance data and used to analyze the coefficient of performance when the design and control of chiller components are changed. The NTU-effectiveness approach was used for the cooling tower model to consider the heat transfer effectiveness at various air-to-water flow ratios and to identify the makeup water rate. Applying load-based speed control to the cooling tower fans and pumps could save an annual plant operating cost by around 15% relative to an equivalent system with constant speed configurations. Copyright © 2010 by the Japan Society of Refrigeration and Air Conditioning Engineering (JSRAE). Source

Hunga W.-T.,Hong Kong Polytechnic University | Mak K.-L.,Hong Kong Community College
INTER-NOISE 2015 - 44th International Congress and Exposition on Noise Control Engineering

The paper describes the development of a simple statistical model to estimate tyre/road noise. For the first time, a total number of 5744 tyre/road noise measurements were collected using a Close-proximity vehicle, from 870 trials along 28 selected road sections on five surface material pavements between 2009 and 2012, to develop such a model in Hong Kong. Six parameters were found to be principle factors of tyre/road noise and were subsequently adopted in the model for predicting tyre/road noise. These parameters include vehicle speed, acceleration, ambient temperature, road temperature, road surface age and road gradient. Further analysis found that vehicle speed and absolute acceleration are the most significant factors at sound frequencies below 1000 Hz. For frequencies between 1250 Hz and 2000 Hz, the road gradient and surface age become more significant. Interaction effects between vehicle speed and absolute acceleration are found to be important for noise levels at frequencies below 1250 Hz. This statistical model was compared to a traditional logarithm speed model in estimating the instantaneous tyre/road noise level. The results show that the new model has more accurate prediction ability than the traditional logarithm speed model, especially for lower frequencies. © 2015 by ASME. Source

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