[Show abstract][Hide abstract] ABSTRACT: This paper presents a new spiral source heat transfer model for simulating the heat transfer performance of pile foundation ground heat exchangers (GHEs) with existence of groundwater transfusion. The model takes heat conduction and convection of groundwater into account and is more accurate than those previously proposed such as solid cylindrical model and ring-coil model to describe the heat transfer behavior. Besides, some shortages and deficiencies are improved and overcome, especially in terms of the configuration of spiral heat transfer tubes. The analytical solutions of the model are obtained to exhibit the temperature response at any point in the underground medium around the pile foundation GHEs. The parameters that exert impacts on the heat transfer process has been investigated and discussed in the paper. The pure conduction case and combined heat transfer case are compared, and the heat exchange efficiency between the pile foundation GHEs and surrounding medium can be improved as a result of the influence of groundwater transfusion. The meliorative effect is becoming increasingly evident with time or velocity of groundwater. The research contributes to more understanding of the potential for pile foundation GHEs and the degrees which the heat transfer efficiency affected by groundwater flow.
International Journal of Heat and Mass Transfer 05/2015; 84. · 2.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: There are three inhabited islands in Hong Kong beyond the reach of the utility grid. Currently they are powered by diesel generators with fuel supplied by barge. To reduce dependence on diesel and improve power supply quality, the government is planning to explore locally available renewable energy for power generation on the islands. In this study, several power supply options such as renewable energy and diesel power generation were considered for one remotely located community. A techno-economic analysis and a detailed hourly simulation were performed to find an optimal autonomous system configuration. The results were evaluated in terms of power supply quality, life cycle cost, payback time, and greenhouse gas emission. The effects of load variation on system configuration and cost were also examined. The feasibility study demonstrates that the hybrid solar–wind–diesel–battery system could provide the optimal techno-economic performance, and this scenario was discussed with elaborate analysis. The study also shows that the energy dispatch strategy is very important for a system consisting of two dispatchable sources. Compared to a fully renewable energy system, the introduction of a back-up diesel generator in the hybrid energy system can be a more viable option, even though high diesel fuel cost is needed.
International Journal of Electrical Power & Energy Systems 02/2015; 65:1–11. · 3.43 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: AimTo investigate the characteristics of the different club drugs and associated high-risk sexual behaviours in China.DesignMulticentre cross-sectional study.SettingDrug Detoxification and Rehabilitation Centres in six provinces, China.ParticipantsA total of 1434 eligible club drug users were included.MeasurementsParticipants were investigated by trained interviewers using a self-designed structured questionnaire to collect information on club drug use and associated behaviours.FindingsMethamphetamine was the most commonly abused drug in participants (73.92%), who used it in their or their friends' homes by non-injection for the purpose of feeling euphoria. Among participants with sexual behaviours after club drug use, 75.21% reported having engaged in sex with multiple partners after club drug use during the past year and 79.84% had unprotected sex after using club drug during the past year. A two-level logistic model showed that male gender [adjusted odds ratio (AOR) = 7.14; 95% confidence interval (CI) = 4.17–12.5], unmarried (AOR = 1.71, 95% CI = 1.04–2.79), long duration of club drug use during their life-time (AOR = 1.76, 95% CI = 1.28–2.42) and severe acute intoxication after using club drugs during the past year (AOR = 2.11, 95% CI = 1.07–4.15) were independent risk factors of multiple sex partners during the past year. Another two-level model showed that the club drug users who were female (AOR = 1.79, 95% CI = 1.03–3.11) and had polydrug use during their lifetime (AOR = 1.55, 95% CI = 1.01–2.34) had more risk for unprotected sex during the past year than without these characteristics.Conclusion
High-risk sexual behaviours are common among club drug users in China. The prevention and intervention of club drug use could decrease the risk of sexual behaviours which further prevent HIV transmission and other sexually transmitted infections in China.
[Show abstract][Hide abstract] ABSTRACT: Liquid desiccant air-conditioning (LDAC) system, which consists of a liquid desiccant ventilation system for dehumidification and an air-handling unit for cooling, has become a promising alternative for conventional technology. To evaluate its feasibility and applicability, the simulation of solar-assisted LDAC (SLDAC) in commercial buildings in five cities of four main climate regions were conducted, including Singapore in Tropical, Houston and Beijing in Temperate, Boulder in Arid and Los Angeles in Mediterranean. Results showed that the system’s performance was seriously affected by the ratios of building’s sensible and latent cooling load. For buildings located in humid areas with low sensible-total heat ratio (SHR), the electricity energy reduction of SLDAC was high, about 450 MW h in Houston and Singapore, which accounted for 40% of the total energy consumption in cooling seasons. The cost payback period was as short as approximately 7 years. The main reason is that the energy required for handling the moisture could be saved by liquid desiccant dehumidification, and the regeneration heat could be covered by solar collectors. For buildings in dry climate with high SHR, the total cooling load was low, but up to 45% electricity of AC system could be saved in Boulder because the chiller COP could be significantly improved during more than 70% operation time. The cost payback period was around 22 years, which was acceptable. However, for the buildings with mild SHR, such as those in Beijing and Los Angeles, the application of SLDAC was not that suitable, in which the electricity energy saved only around 100 MW h and the cost payback period was more than 30 years. The minimum installation area of solar collector should also be fulfilled, or the system would even consume more energy than the conventional ones. It can be concluded that the SLDAC performed best in humid areas and worst in locations with the mild outdoor humidity.
Energy Conversion and Management 12/2014; 88:749–757. · 3.59 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background
Conditioned fear memories can be updated by extinction during reconsolidation, and this effect is specific to the reactivated conditioned stimulus (CS). However, a traumatic event can be associated with several cues, and each cue can potentially trigger recollection of the event. In the present study, we introduced a technique to target all diverse cues associated with an aversive event that causes fear.
In the human experiments, 161 subjects underwent modified fear conditioning, in which they were exposed to an unconditioned stimulus (US) or unreinforced CS to reactivate the memory and then underwent extinction, spontaneous recovery, and reinstatement. In the animal experiments, 343 rats underwent contextual fear conditioning under a similar protocol as the used in the human experiments. We also explored the molecular alterations after US reactivation in rats.
We found that presentation of a lower-intensity US following extinction disrupted the associations between the different CSs and reactivated US in both humans and rats. This effect persisted for at least 6 months in humans and was selective to the reactivated US. This procedure was also effective for remote memories in both humans and rats. Compared with the CS, the US induced stronger endocytosis of AMPA glutamate receptors 1 and 2 and stronger activation of protein kinase A, p70S6 kinase, and cyclic adenosine monophosphate response element binding protein in the dorsal hippocampus in rats.
These findings demonstrate that a modified US retrieval-extinction strategy may have a potential impact on therapeutic approaches to prevent the return of fear.
[Show abstract][Hide abstract] ABSTRACT: Leukocytes can cross intact blood-brain barrier under healthy conditions and in many neurological diseases, including psychiatric diseases. In present study, a cyclic RGD (cRGD) peptide with high affinity for integrin receptors of leukocytes was used to modify liposomes. The cRGD-modified liposomes (cRGDL) showed very high affinity for monocytes in vitro and in vivo and co-migrated across in vitro BBB model with THP-1. The trefoil factor 3 (TFF3), a macromolecular drug, was rapidly and persistently delivered to brain for at least 12 h when loaded into cRGDL while 2.8-fold increase in drug concentration in basolateral amygdala brain regions related to depression was observed. A systemic administration of cRGDL-TFF3 mimicked antidepressant-like effect of direct intra-basolateral amygdala administration of TFF3 solution in rats subjected to chronic mild stress. The effective dual-brain targeting delivery resulting from the combination and co-migration of cRGDL with leukocyte cross BBB may be a promising strategy for targeted brain delivery.
Nanomedicine Nanotechnology Biology and Medicine 11/2014; · 5.98 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Repeated exposure to a neutral conditioned stimulus (CS) in the absence of a noxious unconditioned stimulus (US) elicits fear memory extinction. The aim of the current study was to investigate the effects of mild tone exposure (CS) during slow wave sleep (SWS) on fear memory extinction in humans.
[Show abstract][Hide abstract] ABSTRACT: A novel blue phase-mixed anatase-rutile TiO2 heterogeneous junctions composite, as anode material in lithium ion batteries (LIBs), is built via surface defect induced method. The as-synthesized composites exhibit outstanding rate capability (93 mAh g-1 at 20 C), and good cyclic stability (7.35% capacity loss after 200 cycles at 10 C).
[Show abstract][Hide abstract] ABSTRACT: LDAC (liquid desiccant air-conditioning system) is promising for reducing the energy consumption, and improving the indoor air quality. In this paper, the operation performance of LDAC with internally cooled/heated dehumidifier/regenerator was simulated and optimized. The cooling tower and solar collectors were employed as the cooling/heating source. Four nested iteration loops were developed and solved for system modeling. A typical commercial building in Hong Kong was selected as a case study, which air-conditioning load was obtained by Energy-plus. Results show that with the increase of solar collector area, the electricity consumption of AC (air-conditioning systems) system reduced by 11–35% in original system, but only a part of dehumidification demand was handled with liquid desiccant ventilation, which led to a low chiller COP (coefficient of performance). By adding a cooling coil for the solution entering dehumidifier, the electricity saving effectively increased to 22–47%, while the heat demand for regeneration also increased by 17%. So, a heat exchanger between water leaving regenerator and solution leaving dehumidifier was introduced. With the lower thermal requirement (reduced by 20%) and higher solar fraction (increased from 30 to 40%), the saving further increased to 29–49%, and the required collector area obviously reduced by 50–60% for the similar energy saving purpose.
[Show abstract][Hide abstract] ABSTRACT: A simulation model for modeling photovoltaic (PV) system power generation and performance prediction is described in this paper. First, a comprehensive literature review of simulation models for PV devices and determination methods was conducted. The well-known five-parameter model was selected for the present study, and solved using a novel combination technique which integrated an algebraic simultaneous calculation of the parameters at standard test conditions (STC) with an analytical determination of the parameters under real operating conditions. In addition, the simulation performance of the model was compared with other models, and further validated by outdoor tests, which indicate that the proposed model fits well the entire set of experimental field test I–V curves of the PV module, especially at the characteristic points. After validation, this model was employed to predict the PV system power output under real conditions. The results show that the predictions agree very well with the PV plant field collected data. Thus, the operating performance of a standalone PV system located on a remote island in Hong Kong has been further evaluated with the aid of this model. It is found that the PV array power output is restricted by the status of the battery bank. This research demonstrates that the PV simulation model developed during the study is simple, but very helpful to PV system engineers in understanding the I–V curves and for accurately predicting PV system power production under outdoor conditions.
Renewable and Sustainable Energy Reviews 08/2014; 36:304–315. · 5.51 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Optimal WT (wind turbine) layout patterns relate in detail to the specific conditions of OWF (offshore wind farm) environments and therefore each is different. This paper presents an investigation into optimal WT layout patterns for three OWF configurations (aligned, staggered, scattered) in HK (Hong Kong) waters. A hypothetical OWF (6930 m × 9072 m) are analysed based on twenty years of wind data (1992–2011). For the aligned and staggered WFs, different WT layout separations are studied. The separations varied between 5.0D and 15.0D along the PWD (prevailing wind direction) and 5.0D to 12.0D in the CWD (crosswind direction), where D is the WT rotor diameter. A range of 25 and 45 WTs are placed in the scattered WF, with their layout optimized using the Multi-Population Genetic Algorithm. WF performance is reported for the best ten layout patterns following studies of many different layouts. Results show for this hypothetical OWF, that the optimal WT separation is 14.5D in the PWD and 11.0D in the CWD for the aligned and staggered cases. Thirty WTs are recommended as the optimum number for the scattered WF. The LCOE (levelized costs of energy) were calculated in HK$ terms 1.474/kWh (aligned), 1.467/kWh (staggered), and 1.290/kWh (scattered). APG (annual energy generation) is determined to be 40.80 × 108 kWh (aligned), 40.42 × 108 kWh (staggered), and 33.98 × 108 kWh (scattered), representing 9.48% (aligned), 9.39% (staggered), and 7.89% (scattered) of the annual electricity consumption for HK in 2012. The approach presented can be regarded as a generic method for WT layout optimization.
[Show abstract][Hide abstract] ABSTRACT: Maladaptive memories elicited by exposure to environmental stimuli associated with drugs of abuse are often responsible for relapse among addicts. Interference with the reconsolidation of drug memory can inhibit drug seeking. Previous studies have indicated that the dephosphorylation of the eukaryotic initiation factor 2 α-subunit (eIF2α) plays an important role in synaptic plasticity and long-term memory consolidation, but its role in the reconsolidation of drug memory remains unknown. The amygdala is required for the reconsolidation of a destabilized drug memory after retrieval of drug-paired stimuli. Here, we used conditioned place preference (CPP) and self-administration procedures to determine whether amygdala eIF2α dephosphorylation is required for the reconsolidation of morphine and cocaine memories in rats. We found that the levels of eIF2α phosphorylation (Ser51) and activating transcription factor 4 (ATF4) were decreased after reexposure to a previously morphine- or cocaine-paired context (i.e., a memory retrieval procedure) in the basolateral amygdala (BLA) but not in the central amygdala. Intra-BLA infusions of Sal003, a selective inhibitor of eIF2α dephosphorylation, immediately after memory retrieval disrupted the reconsolidation of morphine- or cocaine-induced CPP, leading to a long-lasting suppression of drug-paired stimulus-induced craving. Advanced knockdown of ATF4 expression in the BLA by lentivirus-mediated short-hairpin RNA blocked the disruption of the reconsolidation of morphine-induced CPP induced by Sal003 treatment. Furthermore, inhibition of eIF2α dephosphorylation in the BLA immediately after light/tone stimulus retrieval decreased subsequent cue-induced heroin-seeking behavior in the self-administration procedure. These results demonstrate that eIF2α dephosphorylation in the BLA mediates the memory reconsolidation of drug-paired stimuli.
Journal of Neuroscience 07/2014; 34(30):10010-21. · 6.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The film wetted area is a significant parameter affecting the heat and mass transfer of falling film liquid desiccant air-conditioning system. In this paper, a theoretical model with the analytical solution was developed for calculating the wetted area accurately, by solving the desiccant interface concentration and temperature gradients. Comparing with the experimental data on a single channel internally heated regenerator, the results with the new model showed better agreement than those of the previous model. The average error reduced significantly from 16.4% to 4.8% for the experiments with different solution temperatures, and decreased from 10.8% to 7.0% for those with different plate surface temperatures. With this new model, decreasing the film thickness and contact angle could significantly increase the film area, and the area also increased with the air and extra fluid temperature. This research is useful to help to predict the wetted area accurately and to increase the area for improving system efficiency of liquid desiccant air-conditioning system and other falling film applications.
International Journal of Heat and Mass Transfer 07/2014; 74:206–209. · 2.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The relationship between thyroid function and depression has long been recognized. Patients with thyroid disorders are more prone to develop depressive symptoms and conversely depression may be accompanied by various subtle thyroid abnormalities. However, the daily rhythm alteration of the functions of the hypothalamus pituitary thyroid axis (HPT) is uncertain. In the present study, we investigated the effects of chronic unpredictable mild stress (CUMS) on the daily rhythm alterations of triiodothyronine (T3), thyroxine (T4), and Thyroid Stimulating Hormone (TSH) in the plasma. We found that CUMS led to depressive-like behavior and the daily rhythm of T3, T4, and TSH in the plasma being disturbed, as well the plasma levels of T3 and T4 decreased compared to control group. Our findings indicate that CUMS not only induce hypofunction of HPT axis but also the disturbance of daily rhythm of PHT axis in rats.
[Show abstract][Hide abstract] ABSTRACT: Repeated exposure to nicotine increases psychomotor activity. Long-lasting neural plasticity changes that contribute to the nicotine-induced development of locomotor sensitization have been identified. The mammalian target of rapamycin complex 1 (mTORC1) signalling pathway is involved in regulating the neuroplasticity of the central nervous system. In this study, we examined the role of mTORC1 in the amygdala in nicotine-induced locomotor sensitization. Rapamycin, an inhibitor of mTORC1, was infused into the basolateral amygdala (BLA) and central amygdala (CeA) or systemically administered to investigate the role of the mTORC1 in the development and expression of nicotine-induced locomotor sensitization. We found that locomotor activity progressively increased during the initiation of nicotine-induced locomotor sensitization and the expression of nicotine sensitization was induced by nicotine challenge injection (0.35 mg/kg s.c.) after five days of withdrawal. The initiation of nicotine-induced locomotor sensitization was accompanied by the increased phosphorylated level of mTORC1 downstream target proteins including p-p70s6k and p-4EBP in the BLA, but not CeA. Intra-BLA infusion or systemic administration of rapamycin blocked locomotor activity. Increased p-p70s6k and p-4EBP were also observed in the expression of nicotine sensitization, which was demonstrated to be inhibited by systemic rapamycin administration. Our findings indicated that mTORC1 activity in the BLA, but not the CeA, mediated the initiation and expression of nicotine-induced locomotor sensitization, and may become a potential target for the treatment of nicotine addiction.
The International Journal of Neuropsychopharmacology 06/2014; 17(11):1-14. · 5.26 Impact Factor