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• Three control methods for water pumps in district heating using ASHPs are proposed. • A new bypass branch is proposed to reduce the energy loss at small heating load. • Power input of water pumps can be decreased by 0–31.84%. • An average decrease rate of 13.40% in power input of ASHP system is obtained. In recent years, the application of air source heat pumps (ASHPs) in centralized heating has grown rapidly in North China. However, there is still lack of theoretical investigation on the control methods of water pump. To decrease the system power consumption, a mathematical model of variable-frequency ASHP used for supplying heating for ten users was established in this work. Meanwhile, three control methods of water pumps were proposed. The heating performance of ASHP system under the three control methods was investigated. Besides, the appropriate control methods of heating terminals under the three control methods were analyzed. Results showed that the minimum relative water flow rate is 30%. Among the three proposed control methods, the power input of water pump is the minimum in the pressure differential control method of the most unfavorable terminal, and its difference with the highest value is 0–31.84%. For the power input of ASHP system, it is always the maximum in constant flow control method, while the minimum in the pressure differential control method of the most unfavorable terminal. Compared with the values in the former control method, the power input of ASHP system in the latter control method decreases by an average of 13.40%. [ABSTRACT FROM AUTHOR]

The shunting technique is regarded as one of the most crucial approaches for suppressing localized secondary flow within a cyclone. This study employs the Reynolds stress model and discrete phase model to investigate the impact of inlet structure and feed operating parameters on the performance of enhanced cyclone with split flow (ECSF), aiming to further enhance its efficiency. The findings demonstrate that the optimum feed velocity of ECSF is 29 m/s, which surpasses that of Lapple cyclone at 23 m/s. In addition, both a contracting inlet and multiple inlets contribute to enhancing the separation efficiency of ECSF. Specifically, ECSF with a contracting inlet exhibits a total separation efficiency of 86.8% for 2.5 μm particles, representing an improvement of 12.3% compared to ECSF with a straight inlet configuration. The enhancement in separation efficiency achieved through the implementation of the four-inlet design is even more pronounced. The segregated particles are directed into the discharge pipe via either underflow or bypass flow, and the trajectory of particle entry into the discharge pipe is closely associated with their cross-sectional positioning prior to entering the cylinder. [Display omitted] • Optimal feed velocity of ECSF is 29 m/s, larger than the 23 m/s of the Lapple cyclone. • Location of feed particles will affect particle trajectories. • ECSF-CI exhibits a total separation efficiency of 86.8% for 2.5 μm particles, 12.3% higher than that of ECSF-SI. • Multiple straight inlets contribute to separation efficiency of ECSF. [ABSTRACT FROM AUTHOR]

Medium-depth ground source heat pumps with borehole heat exchanger are pivotal in energy-saving and decarbonization. The heat transfer performance of borehole is important for design, with stratum thermal conductivity significantly influencing heat exchange, and economic considerations also act as a vital constraint on technological advancements. However, there is limited on-site testing in severe cold regions, especially in the Songliao Basin. Stratum thermal conductivity usually relies on empirical values, and its diverse impacts are not integrated into borehole heat transfer model. Additionally, previous studies optimized borehole design only from the thermal perspective. To address these gaps, we conducted an inaugural test in Shenyang. Geologic-based heat transfer model explores the geological influences, heat transfer performance, and heat extraction cost. At a depth of 2500 m, the formation's thermal conductivity is 2.45 W⋅m⁻1 K⁻1. The heat extraction, at a flow rate of 26.0 m3 h−1, achieves 352.3 kW with an inlet-outlet temperature differential of 11.7 °C. The effects of saturation, porosity, and lithology on stratum thermal conductivity were also explored. Furthermore, considering heat extraction cost, optimal depths for borehole utilizing PE-RT II and stainless-steel vacuum pipe are 2790 m (10.3 CNY·W−1) and 3140 m (10.2 CNY·W−1), with critical depths, 2910 m, governing the selection of economic inner pipe. This research establishes medium-depth ground source heat pumps as the preferred choice for low-carbon transformation in building heating, domestic hot water, and industrial and agricultural heat applications. [Display omitted] • Songliao basin's CBHE field test in severe cold region at a depth of 2500 m. • Achieved heat extraction capacity of 353.2 kW at a flow rate of 26.0 m³·h⁻1. • Utilized a geologic-based CBHE model to elucidate stratum properties influence on heat transfer. • Identified 2910 m as the critical depth for inner pipe selection and optimal depth is determined. [ABSTRACT FROM AUTHOR]

• An enhanced cyclone with split flow (ECSF) is proposed. • The ECSF has higher separation efficiency than that of traditional cyclone. • ECSF is able to suppress the top ash ring and PVC phenomenon. • ECSF achieves a broader range of feed velocity compared to the traditional cyclone. The limitation of cyclone performance is attributed to the presence of localized secondary flow, including longitudinal circulation, short circuit flow and eccentric circulation. The present study proposes an enhanced cyclone with split flow (ECSF) to effectively suppress the local secondary flow in cyclones. An experimental setup was constructed to evaluate the performance of ECSF under various operating conditions. The results of the experiment demonstrate that the separation efficiency of ECSF surpasses that of Lapple cyclone due to the synergistic effect of split flows in both the by-pass flow and underflow. When the feed velocity is 13 m/s, the ECSF exhibits a reduced separation efficiency of 89.8% for 10 μm silica particles, which surpasses that of the Lapple cyclone by 10.6%. The ECSF achieves its maximum total and reduced separation efficiencies at a feed velocity of 27 m/s, reaching values of 96.3% and 95.7%, respectively. Compared to the Lapple cyclone, the ECSF demonstrates an extended range of operational capabilities with respect to feed velocity. By maintaining a constant total split ratio in ECSF while increasing the proportion of by-pass flow, it is possible to improve its separation efficiency without augmenting overall energy consumption. The findings of this investigation offer valuable insights for enhancing the dust removal efficiency of cyclones. [ABSTRACT FROM AUTHOR]

• The response surface method is used to design DFHRE with a conical surface. • Conical surface can control turbulence intensity in DFHRE. • Vortex-finder cannot be inserted too far beyond the cylinder-cone interface. • Increasing the suction angle reduced the separation efficiency. • The effects of the three factors are independent and significant. The structure of the hydrocyclone always changes with the application scene due to its excellent separation performance. A de-foulant hydrocyclone with a reflux ejector (DFHRE) has a completely different flow field structure from that of a conventional one. Under the effect of the reflux ejector, DFHRE has the function of overflow-suck-underflow to achieve continuous discharge and high separation performance. To further improve its separation performance, an inner conical surface was added to control the turbulence intensity, and the suction angle and vortex-finder insertion depth were adjusted to control the intensity of the overflow-suck-underflow. The single factor method and response surface method (RSM) were used to conduct experiments through general-purpose polystyrene particles (GPPS) water and sewage. The results show that the separation performance of DFHRE first increased and then decreased as the lengths of conical surface L c and vortex-finder L v increase, whereas the separation efficiency and the energy consumption changed monotonically with the increase of suction angle α. For the results of RSM, these three factors (L c , α , L v) had significant effects on maximizing separation efficiency and minimizing split ratio, whereas their combined effects were not significant. Finally, the maximum separation efficiency and minimum total pressure drop optimized by the RSM model are 94.62% and 1.09 kPa, respectively. The optimal values of L c , α , and L v was 0.29 (height ratio of inner conical surface to that of the outer cone), 30°, and 0.50 (length ratio of the vortex-finder insertion to the total of cylinder-cone), respectively. Therefore, these three factors must be fully considered for designing DFHRE, and the insertion depth of the vortex-finder can exceed the interface of the cylinder and cone but not too much, which is different from that of the traditional hydrocyclone. [ABSTRACT FROM AUTHOR]

• A downward axial velocity area was found in the center of DFHRE. • The central downward-axial-velocity decreased as the suction angle increased. • The overflow-suck-underflow was enhanced as the inlet velocity increased. • DFHRE had a larger split ratio than that of conventional hydrocyclones. • DFHRE had a higher total pressure drop than that of traditional hydrocyclones. Hydrocyclone has been extensively used in various separation processes. For example, in the sewage source heat pump system, a De-Foulant Hydrocyclone with Reflux Ejector (DFHRE) can fully use the kinetic energy of its overflow to suck its underflow and flush away the foulants flowing out with the underflow. Our previous experiments in 2018 showed that the reflux ejector could prevent the underflow orifice from blocking, and reducing the suction angle could increase the separation efficiency by approximately 10% whereas decreasing its energy consumption markedly. To date, however, its mechanism is still unclear. Therefore, in this study, we used the Particle Image Velocimetry (PIV) method to study the flow field in DFHREs with different suction angles and compared it with that in the traditional hydrocyclone without reflux ejector. Results indicated that, in all the tested DFHREs, there was a negative-axial-velocity area in the center of hydrocyclones, which was not found in the center of the tested traditional hydrocyclone. The negative axial velocity produced by the overflow-suck-underflow decreased with increasing suction angle whereas increased with increasing inlet velocity. The split ratio and total pressure drop of the DFHRE are respectively and approximately 18.5% and 28.3kPa greater than those of the traditional hydrocyclones at the suction angle of 30°. This proved that the experimental performance of the sewage suction ejector used in hydrocyclone, that is, the suction effect of the reflux ejector and the separation efficiency of DFHRE were the best at the suction angle of 30°. Besides, the obtained change of flow field caused by the reflux ejector provided a new idea for enhancing hydrocyclone separation. [ABSTRACT FROM AUTHOR]

• SHAP-1 and SHAP-2 were purified from Sargassum henslowianum. • Structural characterization of SHAP-1 and SHAP-2 was identified. • Both SHAP-1 and SHAP-2 exhibited strong anti-HSV effect. • They interfere with the adsorption of HSV-2 to host cells. Purified fucoidans SHAP-1 and SHAP-2 with apparent molecular weights of 6.55 × 105 and 5.89 × 105, respectively, were isolated from Sargassum henslowianum by ion-exchange and gel-filtration column chromatography. They are both composed of fucose and galactose at a ratio of around 3:1 and 31.9% sulfate. The backbone of two fucoidans consists of α -(1→3)-linked L-Fuc p residues which are mainly sulfated on the C-2 and C-4 positions. Side chains composed of terminally linked α -L-Fuc p and α -D-Gal p residues, and (1→2)-, (1→6)-, and (1→2,6)-linked β -D-Gal p residues attach mainly at O -4 position of backbone residues. Antiviral test showed that the IC 50 values of SHAP-1 and SHAP-2 against HSV-1 were estimated to be 0.89 and 0.82 μg/mL by plaque reduction assay, respectively, whereas both as low as 0.48 μg/mL against HSV-2. The antiviral mechanism of the fucoidans might be at least through blocking HSV-2 virion adsorption to host cells. These results suggest that the fucoidans have potential clinical applications. [ABSTRACT FROM AUTHOR]

• The average heat exchange per meter of 2000 m DBHE is 141.5 W/m at coldest moment. • The recommended insulation length of 2000 m DBHE is 178 m. • One 2000 m DBHE possesses a TER of 13.0 m for one heating period. • The load carrying capacity of 0.04℃·m−1 is 1.33 times better than the 0.03℃·m−1. The deep borehole heat exchanger (DBHE) is a vital part in medium-depth geothermal heat pump system (MD-GHPs). In comparison to other forms of heat exchangers, the DBHE has the following outstanding advantages: the small footprints, the little damage to rock as well as the high efficiency. However, numerous DBHE models were fixed variable values such as flow rate or inlet fluid temperature and there were few studies combining the user heating load variation with the temperature fluctuation on the DBHE side. In order to fill this gap, a DBHE heat transfer model with dynamic building heating load constraint is developed. In this heat transfer model, the load boundary condition is the hourly flow rate and the difference in inlet and outlet water temperature, and the outlet water temperature is obtained through iteration. In addition, this model is validated by a building space heating experiment data in Harbin and guaranteed its correctness. The average heat exchange per meter at the coldest heating moment also ensures the viability of MD-GHPs, which is 141.5 W/m. A series of typical coordinates are used to analyze the effect of DBHE on the surrounding rock, and the concept of DBHE recommended insulation length are proposed. One single DBHE with 2000 m burial depth possesses a temperature effect radius of 13.0 m for one heating period. Besides, some critical conclusions are as follows: For the structural parameter, the recommended insulation length is 178 m. For the operating parameter, there is a minimum value for the total power consumption and 18 m3·h−1 is the recommended optimal flow rate in this situation. For the geological parameter, raising the geothermal gradient can dramatically improve inlet fluid temperature (IFT) and outlet fluid temperature (OFT), and enhance the ability of DBHE to carry the building heating load. When maintaining the same IFT at the coldest moment, the geothermal gradient of 0.04℃·m−1 is 1.33 times more capable of carrying loads than the 0.03℃·m−1. This paper can provide basis for a series of DBHE thermal performance in practical space heating engineering applications of MD-GHPs. [ABSTRACT FROM AUTHOR]

Highlights • A novel wastewater source heat pump based on latent heat transfer is proposed. • Latent heat transfer rate accounts for 72% of total heat transfer capacity. • The novel WWSHP system has comparable COPs to conventaional ones. • This system is able to recover heat from wastewater at temperature as low as 8 °C. Abstract Heat recovery from wastewater is of considerable significance to energy conservation and environmental protection. However, all types of wastewater contain suspended foulant. This leads to fouling on heat exchanger surfaces, resulting in low heat transfer efficiency and blocking heat exchanger. Therefore, the use of wastewater source heat pump (WWSHP) is considerably restricted. In order to avoid the fouling on wastewater heat exchanger (WWHEX) to achieve a better performance, a novel WWSHP system was proposed. The detailed structure and experimental performance evaluation of the operating performances of the novel WWSHP system are described in this paper. The core of this novel WWSHP system was a wastewater tower where circulating air extracted heat from wastewater through the evaporation of water, while the foulant in wastewater would stay. An experimental set-up for the novel WWSHP was established and five experimental cases were organized. In the first four cases, the effects of the variations in key system operating parameters on the operating performances of the novel WWSHP system were experimentally examined. In the fifth case, the overall operating performances of the experimental setup when recovering heat from waste bath water at 29 °C at a preset hot water temperature of 45 °C were experimentally examined. Within the wastewater tower, the main heat transfer process was via latent heat through the evaporation of water, accounting for 72.1% of the total heat transfer exchange. The results of cases 1–4 suggested that with an increase in wastewater temperature, the percentage share of latent heat exchange was also increased. However, the increases in both wastewater flowrate and circulating air flowrate had little effect on the percentage of latent heat exchange in the total heat transfer of the wastewater tower. The novel WWSHP system with the wastewater tower worked well at wastewater temperature of 8 °C, with its COP unit of 2.97 and a COP sys of 2.0 for water heating. Increasing wastewater flowrate from 1.29 m3/h to 1.77 m3/h could help improve the heat transfer rate of the wastewater tower by 4.4% and the COP sys by 2.5%, respectively. On the other hand, the experimental results for case 5 suggested that at wastewater temperature of 29 °C and a preset hot water temperature of 45 °C, the average COP unit was 4.99 and the average COP sys was 3.43, both being higher than those of conventional WWSHPs. [ABSTRACT FROM AUTHOR]

Highlights • An anti-fouling WWSHP system with high efficiency and reliability was proposed. • Working cycle of circulating air in the novel WWSHP system was analyzed detailly. • The novel WWSHP system had an effective anti-fouling performance. • Condensate from the evaporator was very clear in comparison to the sewage. • Evaporator of the novel WWSHP system had very clean surface after 41-day test. Abstract Using wastewater source heat pumps to recover heat from the sewage discharged from buildings could help improve building energy utilization efficiency remarkably, which is a promising technology in near-zero energy buildings and should be widely used. However, fouling deposit would occur on a heat exchanger surface due to the poor water quality of wastewater, which would affect the heat transfer performance and may even block the heat exchanger, reducing the reliability of a wastewater source heat pump unit. Fouling poses a challenge for the wider application of wastewater source heat pumps. A novel anti-fouling wastewater source heat pump system with a wastewater tower was proposed in this work and its operational performances were experimentally investigated based on a long-term test of 41 days (492 h). Experimental results showed that the heat transfer rate in the evaporator of the novel wastewater source heat pump was stable during the 41-day test at an average of 3.80 kW. Unlike in the evaporator of a conventional wastewater source heat pump unit, the total thermal resistance in the evaporator of the novel wastewater source heat pump unit was not increased but only fluctuated around an average of 0.0267 K m2/W throughout the entire 41 days test. The evaporating temperature of the refrigerant stayed stable around an average of 2.74 °C. Furthermore, the coefficient of performance of the unit was also stable at an average of 3.32 and the coefficient of performance of the system maintained an average of 2.13. The condensate drained away from the bottom of the evaporator did not contain any foulant. In addition, the photos for the evaporator showed that its surface was still clean after the 41-day test. Therefore, the experimental results suggested that the novel wastewater source heat pump system not only had superior performance of heat recovery but also achieved effective anti-fouling on its evaporator surfaces. [ABSTRACT FROM AUTHOR]

Low-carbon and high-efficiency mid-depth ground-source heat pumps become a promising heating option for cold regions in China towards carbon neutral. However, system-level evaluation algorithm that incorporates multiple influences are needed. Hence, an economic-energetic-environmental evaluation algorithm for a hybrid mid-depth geothermal heating system was established. It couples load characteristics and reflects the impact of design parameters, geological conditions, and fluctuating factors on three evaluation indicators. The economic performance increases initially as heat pump load ratio and hole depth grow but is more sensitive to the former. A recommended design parameters' zone is given for the general case. Moreover, when the load ratio is 0.65 and the depth is 2750 m, the maximum relative NPV reaches 88.4 million CNY. The peak value of carbon reduction revenue, 54.7 CNY/tCO 2 , appears near the load ratio of 0.63 and the depth of 3300 m. The valley of heating cost, −15.9 CNY/GJ, occurs near the load ratio of 0.66 and the depth of 2600 m. The break-even point of geothermal gradient has a positive linear relationship with the hole completion cost, by which investing feasibility can be determined. Fluctuating factors have a significant impact on the above indicators but will not change the profit-loss status. [Display omitted] • Developed an algorithm for environmental-energetic-economic evaluation. • Algorithm reflects the impact of design parameters, geological conditions, and fluctuating factors. • Recommended design parameters' zone provided, with potential max economy of 88.4 million CNY. • Investment feasibility judged by fitting curve of geothermal gradient vs hole completion cost. • Future fluctuating factors will not affect the system profit-loss status. [ABSTRACT FROM AUTHOR]

The application of microwave absorption (MA) materials in realistic aerospace scenarios would be difficult without a reliable mechanical carrier. However, achieving broad effective absorption bandwidth (EAB) of the aramid honeycomb at low weight gain is still a significant challenge. Herein, we achieved rapid in-situ flowering of RGO with 3D distribution in honeycomb holes by optimizing the hydrophilic thermal (HDT) N 2 H 4 ·H 2 O reduction process, making full use of the internal space of the honeycomb. The synergy of super-broadband MA and ultra-light in aramid honeycomb can be achieved by filling the 3D macro-dispersed flower-like RGO without other media. In the frequencies of 2–18 GHz, the minimum reflection loss (RL min) of −48.38 dB was obtained in a 3% (w/w) RGO-filled honeycomb at 14.80 GHz, with a thickness of 5.2 mm. Moreover, the 3% (w/w) RGO-filled honeycomb composites achieve a broad EAB of 13.84 GHz at the thickness of 9.0 mm with only 3% increase in weight. Actual and simulated MA performance verifies the uniformity and reliability of the foamed RGO-filled honeycomb composites, where the power loss of the composites is mainly based on the conductive losses and multiple polarization from the macroscopic distribution of RGO. The electromagnetic parameters of the foamed RGO-filled honeycomb can precisely be controlled through the weight gain of GO impregnation. Compared to ordinary impregnated coatings with high weight gain, this study provides a simple and effective pathway for preparation of MA honeycomb structures with weight gain less than 4%, which have a significant potential in the field of aerospace stealth. [Display omitted] • Rapid in-situ reduction and foam filling of RGO in honeycomb holes at low hydrazine concentration was achieved. • RGO-filled honeycomb structure achieves a broad EAB of 13.84 GHz at the thickness of 9.0 mm with only 3% increase in weight. • The electromagnetic parameters of honeycomb composites can be precisely controlled. • Foamed RGO-filled honeycomb composites are expected to be used as aviation stealth materials. [ABSTRACT FROM AUTHOR]

An air-conditioner (AC) that uses refrigerant R32 assisted with one-phase vapor injection shows high energy efficiency and low discharge temperature in the heat-pump cycle, but the performance is not satisfactory in the refrigeration cycle. In this study, an improved injection cycle consisting of one-phase vapor injection mode and two-phase injection mode is proposed and integrated into an AC using R32, which is now referred to as an advanced injection-assisted air-conditioner (IAC). Through an experimental and theoretical study, an optimal injection duration of 8 s is attained for maximizing the refrigeration potential of the IAC. Furthermore, in an entire day–night cycle, both the cooling capacity and energy efficiency ratio (EER) of the IAC within the two-phase injection cycle are enhanced by 25% and 32%, respectively, compared with those of a noninjection-assisted AC. Moreover, two-phase injection offers the highest exergetic efficiency, approximately 50% or more in the refrigeration cycle, exhibiting remarkable thermodynamic performance of the IAC. In addition, compared to the conventional AC using R410A, the IAC using R32 within a two-phase injection cycle demonstrates reasonable payback performance and substantial reduction in carbon dioxide and sulfur dioxide emissions in the refrigeration cycle. [ABSTRACT FROM AUTHOR]

• A micro-holes radiant plate without adding dynamic and piping system was designed. • Micro-holes radiant plate combines orifice plate air supply and radiant heat transfer. • The deviation between indoor and set temperature was within 1 ℃ for all types. • The maximum ratio of the radiant heat transfer quantity was close to 70 %. In order to alleviate energy shortage and maintain comfortable indoor environment, radiant air conditioning system is widely used. This paper designs and produces a miniaturized micro-holes radiant plate, which has the characteristics of orifice plate air supply and radiant heat transfer. The micro-holes radiant plate can be installation on the ceiling or sidewall without adding dynamics system and piping system. In order to explore the heating performance of the micro-holes radiant plate under different installation types, an experimental bench of air source heat pump micro-holes radiant plate heating system was built in Harbin, China, for laboratory heating. The experimental results showed that the indoor average temperature under various installation types could basically meet the set requirements, and the deviation was within 1 °C. The indoor horizontal temperature distribution was relatively uniform, and the temperature difference of each measuring point was less than 2 °C. The indoor vertical temperature difference was the smallest under the installation type with sidewall 50 mm from the ground at only 2.68 °C in the sitting position and 3.14 °C in the standing position, which meet China and ASHRAE standards. The ratio of the radiant heat transfer quantity under the sidewall heating was about 60 %, while the ratio under the ceiling heating was only about 30 %. The maximum ratio of the radiant heat transfer quantity was close to 70 % under the installation type with sidewall 50 mm from the ground. The experimental results provide theoretical support for the design and operation of air conditioning systems in severe cold regions. [ABSTRACT FROM AUTHOR]

• Freeze concentration is applied for solution regeneration in heat pump system. • The test unit is able to regenerate the dilute solution from 13% to 15%. • The specific ice production rate is 8.94 kg/kWh. • COP of total energy efficiency is 5.03. • The heat utilization rate is 62.5% and can be used for heating supply water. Freeze concentration, which is often used in water treatment and the food industry, has a good regeneration effect and is easy for latent heat utilization. Therefore, a solution regenerator unit using freeze concentration with a heat pump system (SRFCHP) is proposed in this paper. In winter, SRFCHP can achieve weak antifreeze solution concentration, and the heat capacity of frozen phase transition is used to raise the supply water temperature. To investigate the performance of the SRFCHP system, a test was built in the enthalpy difference laboratory. Results shown that the SRFCHP system was able to regenerate the dilute solution from 13 % to 15 % in five regeneration cycle cycles. Around 34.5 % of ice production was able to be separated and the average loss mass of solute was about 0.95 kg per test in the regeneration cycle. Moreover, the SRFCHP system has a better performance on energy efficiency. About 62.5 % of total heat capacity had been recovered effectively. The solute recovery rate was 69.1 %. The coefficient of performance of refrigeration efficiency and heat recovery efficiency were 2.01 and 3.01, respectively. The specific ice production rate was 11.03 kg/kWh. These results demonstrate that the proposed system can be used in frosting regions to regenerate the dilution liquid. [ABSTRACT FROM AUTHOR]

Sewage contains abundant low-grade heat energy, and recycling it using a heat pump system is an effective way to reduce carbon emissions. The particles in sewage will cause untreated sewage to exhibit non-Newtonian characteristics, and accurate rheological measurement is important for sewage transmission and distribution system design. The traditional rotary rheometer deforms, agglomerates, or breaks the solid particles in sewage, which affects the measurement results. Therefore, in this study, a horizontal tube rheological test bench was built for urban sewage. Constitutive equations and viscosity expressions of untreated and prepared urban sewage at different temperatures and particle concentrations were tested. The results show that untreated and prepared sewage conforms to the shear-thinning model of power-law fluids in non-Newtonian fluids even at particle wet mass concentration as low as 0.103%. The flow characteristic index n of sewage is unrelated to temperature, and its influence is mainly reflected in the consistency coefficient k. However, the sewage flow characteristic index n increases with a decrease in particle concentration. In the laminar flow range of 0.02–0.2 m/s, the flow resistance obtained by treating untreated sewage as a Newtonian fluid was approximately 1.36–1.99 times that of the non-Newtonian fluid model, which will result in a larger power system design and higher energy consumption. Under turbulent flow conditions, the drag coefficient of the Newtonian model was approximately 1.13 times that of the non-Newtonian model. This shows that when designing a sewage source heat pump system, the power-law fluid shear-thinning characteristics of untreated sewage must be fully considered, which helps reduce the calculated energy consumption of transportation. • Constitutive equation for untreated sewage is: τ = 2.78 × 10 − 3 × γ ˙ 0.827. • Particle concentration decreases and the flow characteristic index n increases. • Untreated sewage exhibited non-Newtonian characteristics with the lowest particle concentration 0.103%. • The temperature important effect on the consistency coefficient k, not the flow characteristic index n. • Newtonian model will increase flow resistance by 1.36–1.99 times to calculate untreated sewage. [ABSTRACT FROM AUTHOR]

• A fan coil unit prototype with humidification function is developed. • Average humidity ratio was increased by 5.7 g/kg. • Humidification capacity of the unit is above 200 g/h. • The humidity is maintained at about 30 % at 30 m3/h of fresh air. In order to solve the problem of low relative humidity in buildings and dispersion of existing heating and humidification equipment during the heating season in severe cold regions, a fan coil unit prototype with a humidification module was developed, and the heat is provided by an air source heat pump. The humidification module was made of parallel porous plates, which were infiltrated by the water using principle of capillary siphon. To explore the performance of the unit, an experimental bench was established in Harbin, China. The results show that the developed prototype can provide above 40 % RH while maintaining the room temperature. The heat absorbed by the water evaporation of the rated humidification capacity only accounts for 3.6 % of the nominal heating capacity of the fan coil unit. When unorganized fresh air infiltrated into the building, compared with the case of no humidification, the humidification reduced the temperature only 0.3 °C, the average relative humidity was increased by 33.8 %, the average humidity ratio was increased by 5.7 g/kg in the indoor stable phase, and the predicted percent dissatisfied in the standing occupant decreases to 9.55. Even if 30 m3/h of fresh air with low temperature and humidity was introduced into the building, the unit can ensure that the indoor temperature was above 20 °C and the relative humidity can be maintained at 30 %. In addition, in the rising stage of temperature and humidity, the humidification capacity of the unit is above 200 g/h. [ABSTRACT FROM AUTHOR]

• Maximum thermal conductivity is 2.10 W·m−1·K−1, ahead of similar studies. • Too high a sand-to-cement ratio will diminish the thermal conductivity. • High porosity leads to a larger permeability and poor thermal performance. • Thermal-conductivity prediction model was developed with an error of less than 10%. • Silica sand is better than river sand in performance. The annulus zone between the vertical ground heat exchanger and borehole wall needs to be filled with grout to enhance heat exchange and prevent groundwater pollution. However, studies on porosity, the dual influence of water-to-cement and sand-to-cement ratios on material properties and theoretical studies need to be deepened. Hence, the flowability, thermal conductivity, and porosity of cement-based grouts with various proportions were tested. It was found that the increase in the sand-to-cement ratio and decrease in the water-to-cement ratio helps in the augmentation of thermal conductivity and decrease of porosity, but lowers the flowability. When the water-to-cement ratio is 0.55, a sand-to-cement ratio higher than 2.0 will lead to excessive fissures and thus weaken the thermal conductivity. The maximum thermal conductivity reaches 2.10 W·m−1·K−1 in the saturated state with a porosity of 0.2442. A high porosity indicates a larger permeability and poor thermal performance; therefore, the suggested porosity is below 0.43. Moreover, the thermal conductivity-change mechanism was studied by the series–parallel thermal conductivity model, which can predict the thermal conductivity with an error of less than 10 %. The model shows that the heat conduction of the components in the grout is mainly in series. Additionally, improving the sand-to-cement ratio, maintaining high saturation, reducing the porosity, and adding high-performance aggregates are all ways to improve the thermal conductivity of the material. And the grouts-taking value area is also marked out. [ABSTRACT FROM AUTHOR]

Cement-based material is frequently used in many aspects. For example, it is used as a sort of grout in a ground source heat pump system, whose heat conduction performance directly affects the heat change efficiency of the vertical ground heat exchanger. However, there are few thermal conductivity models applicable to cement-based grout materials, and the accuracy of published models needs to be improved. Therefore, a thermal conductivity prediction model for cement-based materials was performed according to the structure and heat conduction equation, which can predict the influence of many factors on thermal conductivity, such as aggregate content (sand-cement ratio), porosity and saturation degree. The overall accuracy is high, with 39 sets of data (75% of the data volume) whose errors are less than ±10%, meeting engineering applications, while the error using existing models mostly exceeds ±20%. This model can also predict a large proportioning range with the water-cement ratio from 0.3 to 0.7, the sand-cement ratio from 0.5 to 3.0, and the saturation degree from 0 to 1. Based on the model prediction results, the variation maps of different sand-cement ratios and porosity under dry and saturated conditions were proposed, and the simplified fitting formula for a range of common values was given. • A thermal conductivity prediction model of cement-based grouts is established. • The model's accuracy is high enough, with 75% of the data's error less than 15%. • The model covers a broad range of proportions and can predict the effect of 4 factors. • The prediction maps of cement-based grouts and their fitting formulas were given. [ABSTRACT FROM AUTHOR]

• A thermo-hydraulic coupling model for residential building heating system was proposed. • Thermal zones divide detailed and each user could regulate his heat in the simulation model. • Infiltration rates and increased thermal resistance of buried pipes are considered in the model. • The calibrated model could respond to heating and hydraulic conditions based on users' regulation. Demand-side regulation is a practical method to decrease the overheating loss and improve comfort level of users. The existing simulation model methods are difficult to evaluate the interaction of user regulation. And there is still no reasonable model method to prove the feasibility of demand-side regulation. To solve this problem, a residential building heating system model considering the thermo-hydraulic coupling and demand-side regulation was built on TRNSYS 18. It was calibrated by a residential building in Harbin. Results showed that using infiltration rates recommended by ASHARE as stochastic calibration parameters, the users that met the validation criteria would increase by 7%. The increased thermal resistance caused by internal surface fouling in the buried pipe should also regarded as a stochastic parameter in the calibration process. After calibrated these two stochastic parameters, the model achieved satisfactory accuracy and all the 144 users met the validation criteria. The calibrated model could provide the ability to simulate the various regulation behaviors of each user, and truly response to heating and hydraulic conditions based on users' regulation. The validated simulation model can be leveraged as a rigorously validated benchmark residential heating system based on demand-side regulation. [ABSTRACT FROM AUTHOR]

• A high-accuracy thermo-hydraulic couplings model of a multi-family residential heating system. • A new index was defined to evaluate the effect of unheated users in the building scale. • Effects of the unheated user on adjacent heating user and the whole heating building were investigated. • All possible relative locations and different indoor temperature settings were investigated. In the Chinese district heating network, unheated users generally exist in multi-family residential buildings, which adversely affects the heating performance of the whole building and its surrounding users. These effects are directly related to the fairness of heat metering and the rationality of system adjustment. Aiming to study this effect, a model of a multi-family residential heating system that considering the thermo-hydraulic coupling is developed and calibrated. Then, the possible adjacencies between unheated and heating users are described by eight different building areas and three relative user locations. Furthermore, based on the model, this paper analyses the effect of the unheated user on the heating users in different adjacencies and adjustment conditions. Lastly, the influence of unheated users in different areas is studied under different adjustment conditions. The result shows that upside unheated user has the most significant effect on heating users. Under the original condition, the building system is most affected by the unheated user on the ground floor, with a relative heat consumption rate (RHCR) greater than 45%. Under the adjustment condition, the RHCR of the system increases significant, but the difference between unheated users is noticeably reduced; the RHCR is 50–70%. [ABSTRACT FROM AUTHOR]

As a widely used technique, vapor injection plays an important role in air source heat pumps (ASHPs) which operate across a wide range of ambient temperatures. The one of primary solutions has been reported to be vapor injection based on flash-tank (FT) and intermediate heat exchanger (IHX) loops respectively. In this paper, vapor injection and its two typical configurations are experimentally investigated in an ASHP prototype. The results show that in the vapor-injection based ASHPs, the performance of FT based ASHPs is better than that of IHX based ones, and injected vapor improves mass flow rate and distribution of working fluid, with a hidden decreasing effect of exhaust entropy. In order to explore theoretical reasons, a whole system model is presented that quantifies performance enhancement potential of FT based and IHX based ASHPs respectively. The calculation results show increased refrigerant mass flow rate, its optimum distribution, and moderate injected vapor entropy contribute to performance improvement of vapor-injection based ASHPs. Further, we also visualize synergy between refrigerant mass flow and injected entropy from perspective of negentropy. At the negentropy level, FT based rather than IHX based loop brings higher heating capacity and efficiency, which is consistent with measurements from experimental research. • Refrigerant mass flow has a significant incentive effect on ASHP performance. • The positive impact of injected entropy toward ASHP performance is demonstrated. • The synergy between mass flow and injected entropy is dominant in RI loops. • The impact of flash-tank based and sub-cooler based RI is quantitatively measured. [ABSTRACT FROM AUTHOR]

• The increase in chitosan and nano-silicon aerogel significantly improves the properties of the composite film. • The composite film has a uniform, non-porous, continuous dense surface with excellent surface properties. • The composite film has strong antibacterial activity against E. coli and S. aureus. The chitosan/okra powder/nano-silicon aerogel composite films were prepared by casting method and their physicochemical properties and structural characterization were studied. The results showed that the composite film had good mechanical properties, barrier properties and optical properties. The composite film has strong flexibility. The surface glossiness of C/D/S1.5:1:0.1 film was 14.4Gu. As for the antibacterial activity, all the composite films had strong antibacterial activity against Gram-negative (E. coli) and Gram-positive (S. aureus), and the inhibition zone of C/D/S1.5:1:0.10 against E. coli reached 551.96 mm2, the inhibition zone for S. aureus was 350.29 mm2. The composite film had uniform, non-porous, continuous and dense surface characteristics. The structural characterization confirmed that there was good compatibility between chitosan, okara powder and nano-silicon aerogel. In summary, the composite films had excellent performance and structure, which promoted the research of functional packaging films. [ABSTRACT FROM AUTHOR]

Vision science and visual neuroscience seek to understand how stimulus and sensor properties limit the precision with which behaviorally-relevant latent variables are encoded and decoded. In the primate visual system, binocular disparity-the canonical cue for stereo-depth perception-is initially encoded by a set of binocular receptive fields with a range of spatial frequency preferences. Here, with a stereo-image database having ground-truth disparity information at each pixel, we examine how response normalization and receptive field properties determine the fidelity with which binocular disparity is encoded in natural scenes. We quantify encoding fidelity by computing the Fisher information carried by the normalized receptive field responses. Several findings emerge from an analysis of the response statistics. First, broadband (or feature-unspecific) normalization yields Laplace-distributed receptive field responses, and narrowband (or feature-specific) normalization yields Gaussian-distributed receptive field responses. Second, the Fisher information in narrowband-normalized responses is larger than in broadband-normalized responses by a scale factor that grows with population size. Third, the most useful spatial frequency decreases with stimulus size and the range of spatial frequencies that is useful for encoding a given disparity decreases with disparity magnitude, consistent with neurophysiological findings. Fourth, the predicted patterns of psychophysical performance, and absolute detection threshold, match human performance with natural and artificial stimuli. The current computational efforts establish a new functional role for response normalization, and bring us closer to understanding the principles that should govern the design of neural systems that support perception in natural scenes.

Convective drying is an effective method for reducing the moisture content of the sludge. Fewer studies have discussed the effect of sludge physicochemical properties on drying compared to air parameters. Eleven types of sludge were collected, and ultimate analysis, proximate analysis, and heat value analysis were performed. Meanwhile, the maximum drying rate (u max ) of sludge convection drying at 70 °C was determined. The results showed that the cumulative variance contribution of the two extracted principal components (PCs) was 92.5 %. Then, a regression model of u max was developed based on the extracted PCs. The coefficient of determination of this model was 0.788, and the difference was statistically significant, with a negative correlation between u max and PC2. Further, the principal component score plot enabled the traceability of the integrated sludge, and based on this classification results, the drying characteristics of various types of sludge were discussed, and a high correlation (R 2  = 0.9590) between the initial moisture content of sludge and u max was found. Mathematical models between sludge physicochemical properties and drying characteristics can be effectively developed from both sludge composition and type scales. This exploration deepened the knowledge of sludge drying and facilitates the prediction of drying rate., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Action representation of man-made tools consists of two subtypes: structural action representation concerning how to grasp an object, and functional action representation concerning the skilled use of an object. Compared to structural action representation, functional action representation plays the dominant role in fine-grained (i.e., basic level) object recognition. However, it remains unclear whether the two types of action representation are involved differently in the coarse semantic processing in which the object is recognized at a superordinate level (i.e., living/non-living). Here we conducted three experiments using the priming paradigm, in which video clips displaying structural and functional action hand gestures were used as prime stimuli and grayscale photos of man-made tools were used as target stimuli. Participants recognized the target objects at the basic level in Experiment 1 (i.e., naming task) and at the superordinate level in Experiments 2 and 3 (i.e., categorization task). We observed a significant priming effect for functional action prime-target pairs only in the naming task. In contrast, no priming effect was found in either the naming or the categorization task for the structural action prime-target pairs (Experiment 2), even when the categorization task was preceded by a preliminary action imitation of the prime gestures (Experiment 3). Our results suggest that only functional action information is retrieved during fine-grained object processing. In contrast, coarse semantic processing does not require the integration of either structural or functional action information., (© 2023. The Psychonomic Society, Inc.)

Introduction: This study aimed to predict the fracture resistance of a mandibular first molar (MFM) with diverse endodontic cavities using finite element analysis (FEA)., Methods: Five experimental finite element models representing a natural tooth (NT) and 4 endodontically treated MFMs were generated. Treated MFM models were with a traditional endodontic cavity (TEC) and minimally invasive endodontic (MIE) cavities, including guided endodontic cavity (GEC), contracted endodontic cavity (CEC) and truss endodontic cavity (TREC). Three loads were applied, simulating a maximum bite force of 600 N (N) vertically and a normal masticatory force of 225 N vertically and laterally. The distributions of von Mises (VM) stress and maximum VM stress were calculated., Results: The maximum VM stresses of the NT model were the lowest under normal masticatory forces. In endodontically treated models, the distribution of VM stress in GEC model was the most similar to NT model. The maximum VM stresses of the GEC and CEC models under different forces were lower than those of TREC and TEC models. Under vertical loads, the maximum VM stresses of the TREC model were the highest, while under the lateral load, the maximum VM stress of the TEC model was the highest., Conclusion: The stress distribution of tooth with GEC was most like NT. Compared with TECs, GECs and CECs may better maintain fracture resistance, TRECs, however, may have a limited effect on maintenance of the tooth resistance., (© 2023. The Author(s).)

Our study aimed to examine the shared and distinct structural brain alterations, including cortical thickness(CT) and local gyrification index(LGI), and cognitive impairments between the early course stage of drug-naïve schizophrenia(SZ) and bipolar disorder(BD) patients when compared to healthy controls(HCs), and to further explore the correlation between altered brain structure and cognitive impairments. We included 72 SZ patients, 35 BD patients and 43 HCs. The cognitive function was assessed using the MATRICS Consensus Cognitive Battery. Cerebral cortex analyses were performed with FreeSurfer. Furthermore, any structural aberrations related to cognition impairments were examined. Cognitive impairments existed in SZ and BD patients and were much more severe and widespread in SZ patients, compared to HCs. There were no significant differences in LGI among three groups. Compared to HCs, SZ had thicker cortex in left pars triangularis, and BD showed thinner CT in left postcentral gyrus. In addition, BD showed thinner cortex in left pars triangularis, left pars opercularis, left insula and right fusiform gyrus compared to SZ. Moreover, our results indicated that CT in many brain areas were significantly correlated with cognitive function in HCs, but only CT of left pars triangularis was correlated with impaired social cognition found in SZ. The findings suggest that changes of CT in the left pars triangularis and left postcentral gyrus may be potential pathophysiological mechanisms of the cognition impairments in SZ and BD, respectively, and the divergent CT of partly brain areas in BD vs. SZ may help distinguish them in early phases., Competing Interests: Conflict of interests All the authors assure that there are no conflicts of interest., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Not every item in a stimulus ensemble equally contributes to the perceived ensemble average. Rather, items with feature values close to the ensemble mean (inlying items) contribute stronger compared to those items whose feature values are further away from the mean (outlying items). This nonuniform weighting process, named robust averaging, has been interpreted as evidence against an optimal integration of sensory information. Here, however, we show that robust averaging naturally emerges from an optimal integration process when sensory encoding is efficiently adapted to the ensemble statistics in the experiment. We demonstrate that such a model can accurately fit several existing datasets showing robust perceptual averaging in discriminating low-level stimulus features such as orientation. Across various feature domains, our model accurately predicts subjects' decision accuracy and nonuniform weighting profile, and both their dependency on the specific stimulus distribution in the experiments. Our results suggest that the human visual system forms efficient sensory representations on short time-scales to improve overall decision performance., (Copyright © 2022 The Author(s). Published by Elsevier B.V. All rights reserved.)

Purpose: To investigate the factors associated with live births and the interaction between age and the number of embryos transferred after in vitro fertilisation (IVF) treatment., Methods: This study analyses data from a population-based-assisted reproductive database of all registered artificial reproduction institutions (n = 80) from 2010 to 2016 in Taiwan. The probability of a live birth in correlation with the treatment parameters was measured with multivariate logistic regression analyses using the generalised additive model (GAM) and Pearson's chi-square exact test., Results: A total of 104,015 IVF treatments performed between 2010 and 2016 were included in our analysis. From these treatments, 31,467 (30.3%) were successfully delivered, and 40,565 test-tube babies were born. Pearson's chi-square exact test indicated that parents' age, cause of infertility, type of ovarian stimulation, additional assisted reproductive technology techniques, donated egg or sperm, fresh or frozen embryo, presence or absence of ovarian hyperstimulation syndrome, and day of embryo transfer were significantly associated with live births after an IVF cycle (p < 0.05). Multiple logistic regression analysis with the GAM revealed that the odds of a live birth with IVF treatment in patients < 34 years of age were 2.55 times higher than that in patients ≥ 45 years of age (odds ratio = 2.55, 95% confidence interval = 1.69-2.90) for patients who underwent a single-embryo transfer (SET); a similar pattern was observed when two or more embryos were transferred. Egg donation, the assisted hatching technique, oral ovarian stimulation agents, and implantation of frozen embryos during SET were shown to improve the chance of a live birth by 29-90%. Implantation of the embryo after the 5th day of culture yielded the highest odds of a live birth. The interaction plot revealed that maternal age, especially < 40 years, was associated with the probability of a live birth. SET and double-embryo transfer showed similar associations with the probability of a live birth across age groups. Transferring more than two embryos might reduce the probability of a live birth during IVF treatment for women ≥ 40 years of age., Conclusions: Implanting a greater number of embryos did not improve the age-related decrease in fertility for patients undergoing IVF. Therefore, we suggested that ≤ 2 blastocysts could be transferred during IVF treatments for women ≥ 40 years. Transferring a blastocyst on day 5 of culture was associated with a significant increase in the odds of a live birth resulting from IVF., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Objective: To investigate the role of the application of role-play in endodontic study in improving the communication skills of Chinese dental undergraduates prior to their direct interactions with patients at the Fourth Military Medical University’s School of Stomatology, China. Methods: Students were recruited from the 5-year bachelor’s programme (n = 36) and randomly divided into six groups, and from the 8-year DDS programme (n = 10) and randomly divided into two groups to participate in the role-play training. Cases selected randomly from the case pool were distributed to the groups. The teacher gave an outline of the roles in the simulation. Each member of each group randomly selected their own role for the role-play. Four types of surveys were distributed to students and faculty members at different points after the role-plays had taken place, to evaluate their attitude towards the use of role-plays in endodontic study. Frequency analysis and a one sample t test were used to describe and analyse students’ acceptance of role-play as a teaching technique. The level of statistical significance was set at P < 0.05. Results: Students’ performance and satisfaction as well as the supporting faculty responses were very favourable towards role-playing. In total, 93.5% of students responded favourably to the role-play, answering ‘strongly agree’ or ‘agree’ to the positive statements about their role-play performance. A total of 95.1% of students stated that they had benefited psychologically and technically from the role-play (‘strongly agree’ or ‘agree’) after their 1-year rotating internship. Conclusion: The application of role-play in endodontic study is an effective way of educating Chinese dental undergraduates and can be beneficial for their transition from students to dentists.

Alcohol consumption is a significant public health issue worldwide. The rat model and epidemiological studies have both reported conflicting results about the effects of alcohol on the kidneys. We aimed to explore the relationships between alcohol consumption and chronic kidney disease. Data from the National Health Interview Survey, the National Health Insurance research database, and the National Deaths Dataset were used. Standardized in-person interviews were executed in 2001, 2005, and 2009 to obtain the demographic characteristics of study population. The participants were followed up until 2013. The primary outcome was new-onset chronic kidney disease. We analyzed 45,200 adults older than 18 years (50.8% men and 49.2% women), and the overall mean (SD) age was 42.73 (16.64) years. During the 8.5 (3.5) years of follow-up, new-onset chronic kidney disease was recognized in 1535 (5.5%), 292 (2.7%), and 317 (4.9%) non-drinking, social-drinking, and regular-drinking participants, respectively. The participants who were social and regular drinkers had a significantly decreased risk of chronic kidney disease incidence (social drinking: adjusted hazard ratio (HR), 0.85; 95% confidence interval (CI), 0.74-0.97; p = 0.018; regular-drinking: AHR, 0.85; 95% CI, 0.74-0.98; p = 0.024), with baseline demographics and comorbidities adjusted. In conclusion, social and regular drinkers had decreased risk of chronic kidney disease when compared with non-drinkers.

Action representation of manipulable objects has been found to be involved in object recognition. Recently, studies have indicated the existence of two distinct action systems: functional action specifying how to use an object and structural action concerning how to grasp an object. Despite evidence revealing the systems' anatomical and functional differences, few preceding studies have dissociated their respective roles in object recognition. The present study aimed to tease apart their roles in the recognition of manipulable objects with a priming paradigm. Specifically, we used static stimuli (photos, Experiments 1 and 2) and dynamic stimuli (video clips, Experiments 3 and 4) depicting functional and structural action hand gestures as primes and measured the magnitude of functional and structural action priming effect in object recognition. We found that static and dynamic priming stimuli induced a robust action priming effect only for functional action prime-target pairs. Naming latencies of the target objects were shorter when functional action representations of the prime and target were congruent than when they were incongruent. Moreover, as compared to static priming photos, dynamic priming stimuli induced a larger functional action priming effect. By contrast, neither static nor dynamic priming stimuli elicited a structural action priming effect. Behavioral data from our four experiments provide consistent evidence of the dominant role of functional action representation in the recognition of manipulable objects, suggesting that action knowledge regarding how to use rather than grasp an object is more likely an intrinsic component of objects' conceptual representation.

Background: In 2003, a major epidemic of human immunodeficiency virus emerged among injection drug users in Taiwan. In response to the twin epidemics of HIV and intravenous drug addiction, the government implemented comprehensive harm reduction programs beginning in 2005. Collected data from relevant agencies were used to explore the impact of the harm reduction programs on HIV and illicit drug use., Methods: This study divided 2002-2015 into three intervention phases and used the surveillance data and statistics on the HIV epidemic, drug abuse, and the intervention from relevant agencies to explore the correlations between different variables in different intervention periods and the combination effects of interventions on the HIV epidemic., Results: In the pre-intervention phase, the growth of the HIV epidemic followed the rapidly increasing number of heroin users, reaching a peak in 2005. After the initiation of harm reduction programs, the HIV epidemic ceased growing, even rapidly declining with the expansion of needle and syringe exchange programs and opioid substitution therapy; however, the number of heroin users remained high. When the implementation of the needle and syringe exchange programs and the opioid substitution therapy program reached the plateau level in the consolidation phase, the number of heroin users also decreased rapidly. The combination effects of the harm reduction programs in this period also pushed levels of HIV infection below those before this outbreak., Conclusions: The HIV epidemic among injection drug users incorporates the dual problems of drug addiction and needle-sharing behaviors, so the use of a single intervention will not resolve all of the problems. Facing a severe HIV epidemic among injection drug users, quickly scaling up and promoting comprehensive harm reduction programs is a good strategy that can be used to simultaneously reverse the HIV epidemic and to resolve the illicit drug use problems. More research is needed to find out the reasons behind why there were cases that declined opioid substitution therapy, so that efforts can be undertaken to avoid the epidemic rebounding.

Acute pulpitis (AP), one of the most common diseases in the endodontics, usually causes severe pain to the patients, which makes the search for therapeutic target of AP essential in clinic. Toll-like receptor 4 (TLR4) signaling is widely involved in the mechanism of pulp inflammation, while melatonin has been reported to have an inhibition for a various kinds of inflammation. We hereby studied whether melatonin can regulate the expression of TLR4/NF-ĸB signaling in the pulp tissue of AP and in human dental pulp cells (HDPCs). Two left dental pulps of the adult rat were drilled open to establish the AP model, and the serum levels of melatonin and pro-inflammatory cytokines, including interleukin 1β (IL-1β), interleukin 18 (IL-18) and tumor necrosis factor α (TNF-α), were assessed at 1, 3 and 5 d post injury. At the same time points, the expression of TLR4 signaling in the pulp was explored by quantitative real-time PCR and immunohistochemistry. The AP rats were administered an abdominal injection of melatonin to assess whether melatonin rescued AP and TLR4/NF-ĸB signaling. Dental pulp injury led to an approximately five-day period acute pulp inflammation and necrosis in the pulp and a significant up-regulation of IL-1β, IL-18 and TNF-α in the serum. ELISA results showed that the level of melatonin in the serum decreased due to AP, while an abdominal injection of melatonin suppressed the increase in serum cytokines and the percentage of necrosis at the 5 d of the injured pulp. Consistent with the inflammation in AP rats, TLR4, NF-ĸB, TNF-α and IL-1β in the pulp were increased post AP compared with the baseline expression. And melatonin showed an inhibition on TLR4/NF-ĸB signaling as well as IL-1β and TNF-α production in the pulp of AP rats. Furthermore, melatonin could also regulate the expression of TLR4/NF-ĸB signaling in LPS-stimulated HDPCs. These data suggested that dental pulp injury induced AP and reduced the serum level of melatonin and that supplementation with melatonin may have a protective effect on AP by modulating TLR4/NF-ĸB signaling in the pulp and in pulp cells.

Background: Methadone treatment was introduced in Taiwan in 2006 as a harm-reduction program for injection drug users (IDUs), among whom HIV was endemic. We examined the association of HIV serostatus with demographic characteristics, substance use, and sexual behaviors among IDUs at methadone clinics in Taipei, Taiwan., Methods: During 2012-2013, IDUs at methadone clinics in Taipei were recruited to complete a risk assessment interview and undergo serologic testing for HIV infection. Correlates of HIV infection were identified by multivariate logistic regression., Results: Of the 827 eligible participants, 85.9% were male, median age was 45 years, and mean years of injecting was 18.0 (range 1-56). The prevalence of HIV infection was 17.7%. In multivariate analysis, HIV infection was significantly associated with age ≤ 45 years (adjusted odds ratio [AOR] = 1.62, 95% confidence interval [CI] 1.01-2.62), being divorced (AOR = 1.67, 95% CI 1.06-2.62), deriving the majority of income during the previous 6 months from temporary jobs or other noncriminal sources (AOR = 1.53, 95% CI 1.02-2.30), unstable housing during the previous 6 months (AOR = 1.47, 95% CI 1.003-2.15), higher number of incarcerations (AOR = 1.14, 95% CI 1.03-1.26), and a history of overdose (AOR = 1.51, 95% CI 1.01-2.28)., Conclusions: Taiwanese IDUs at methadone clinics have a relatively high HIV prevalence, which was associated with younger age and history of overdose. It is imperative to educate IDUs' about HIV transmission, particularly for the younger and overdosed IDUs.

Purpose: To explore the mechanism of failure of ProTaper NiTi handfiles during root canal preparation., Methods: A total of 2061 discarded ProTaper handfiles were collected after clinical use. The files were studied under stero-microscope to determine the type of defect. The fractured files were photographed digitally and the pictures were analyzed by software Image-Pro Plus to measure the distance from the break point to the tip. The data were statistically analyzed by using SPSS 11.0 software package., Results: Plastic deformation was observed in 166 files (8.2%), and the types of defects included unwinding, winding flutes, and plastic bending. Instrument separation occurred in 581 files (28.2%), and the fracture rate was the highest in the F2 file group (41.7%). The SX file group had the highest facture level, and the mean distance from the breakpoint to the file tip was (4.4±1.1) mm., Conclusions: For shaping files, especially at the apical level, the main cause of mental failure is overload of torque, whereas for finishing files, especially at the higher level, is cycle fatigue. Understanding the defect types of ProTaper handfiles is useful for avoiding file breakage during root canal therapy.

Background: Injecting drug users (IDUs) in Taiwan contributed significantly to an HIV/AIDS epidemic in 2005. In addition, studies that identified risk factors of HCV/HIV co-infection among IDUs were sparse. This study aimed to identify risk factors of HCV/HIV co-infection and HCV mono-infection, as compared with seronegativity, among injecting drug users (IDUs) at a large methadone maintenance treatment program (MMTP) in Taipei, Taiwan., Methods: Data from enrollment interviews and HCV and HIV testing completed by IDUs upon admission to the Taipei City Hospital MMTP from 2006-2010 were included in this cross-sectional analysis. HCV and HIV testing was repeated among re-enrollees whose HCV or HIV test results were negative at the preceding enrollment. Backward stepwise multinomial logistic regression was used to identify risk factors associated with HCV/HIV co-infection and HCV mono-infection., Results: Of the 1,447 IDUs enrolled, the prevalences of HCV/HIV co-infection, HCV mono-infection, and HIV mono-infection were 13.1%, 78.0%, and 0.4%, respectively. In backward stepwise multinomial regression analysis, after controlling for potential confounders, syringe sharing in the 6 months before MMTP enrollment was significantly positively associated with HCV/HIV co-infection (adjusted odds ratio [AOR]=27.72, 95% confidence interval [CI] 13.30-57.76). Incarceration was also significantly positively associated with HCV/HIV co-infection (AOR=2.01, 95% CI 1.71-2.37) and HCV mono-infection (AOR=1.77, 95% CI 1.52-2.06), whereas smoking amphetamine in the 6 months before MMTP enrollment was significantly inversely associated with HCV/HIV co-infection (AOR=0.44, 95% CI 0.25-0.76) and HCV mono-infection (AOR=0.49, 95% CI 0.32-0.75). HCV seroincidence was 45.25/100 person-years at risk (PYAR; 95% CI 24.74-75.92/100 PYAR) and HIV seroincidence was 0.53/100 PYAR (95% CI 0.06-1.91/100 PYAR) among re-enrolled IDUs who were HCV- or HIV-negative at the preceding enrollment., Conclusions: IDUs enrolled in Taipei MMTPs had very high prevalences of HCV/HIV co-infection and HCV mono-infection. Interventions such as expansion of syringe exchange programs and education regarding HCV/HIV prevention should be implemented for this high-risk group of drug users.

Objective: To investigate the anatomic features of the root apexes of permanent three-rooted mandibular first molars., Methods: A total of 122 permanent mandibular first molars of Han Chinese patients were collected. Twenty three-rooted and 25 two-rooted molars were scanned by micro-CT and then reconstructed three-dimensionally. The apical anatomy of the tooth models were analyzed in software Mimics 10.01. The long and short diameters of the apical constriction (AC), the distances between AC, apical foramen (AF) and apex were measured. One-way ANOVA and LSD-t tests were used to compare the groups in relation to AC diameter and the distances between the AC, AF and apex., Results: The AF of the mesiobuccal (MB) canals most frequently presented at the distal side of the apex (10 cases in three-rooted and 6 cases in two-rooted group), and of the mesiolingual (ML) canals, most often at the lingual side (8 cases in each group). The AF of the distobuccal (DB) roots were frequently located at the distolingual (DL) side (10 cases), and those of the DL roots and distal canals of two-rooted molars were most often at the buccal (7 cases) and distal (11 cases) sides, respectively. The percentage of the "classical" singular AC was 53% (80/151). The average long(D) and short(d) diameters of the AC of the DB canals were (0.32 ± 0.09) mm and (0.25 ± 0.05) mm, respectively, significantly larger than the DL canals [D = (0.27 ± 0.08) mm, d = (0.22 ± 0.06) mm, P < 0.05] and the ML canals [D = (0.24 ± 0.06) mm, d = (0.19 ± 0.06) mm, P < 0.01). In three-rooted group, the mean distances between AC and AF, AF and apex, and AC and apex were (0.67 ± 0.32), (0.49 ± 0.28) and (1.01 ± 0.34) mm, respectively., Conclusions: The AF of three-rooted mandibular molars frequently deviate from the root apex, and the AC of the DB canal is wider than those of the other canals. The mean distances between AC, AF and the apex suggest that root canal therapy should terminate at 1 to 1.5 mm short of the radiographic apex.

Objective: To observe the ability of SD rat dental papillae cells forming dentin-like structure induced by millipore filter combined with transforming growth factor-β(1) (TGF-β(1))., Methods: The first passage SD rat dental papillae cells were enzymatically dissociated and centrifuged to obtain a cell mass. The cell mass was seeded on the millipore filter combined with TGF-β(1). The complex was incubated for 6 d in vitro or transplanted under the renal capsule for 2 weeks. Then the differentiation of dental papillae cells on the filter and the formation of mineral tissue on the implant were analyzed., Results: A layer of polarized columnar cells were observed along the surface of the millipore filter, with cell processes extending into the porous media. Dentin sialoprotein (DSP) and dentin matrix protein-1 (DMP-1) were positive in these cells. After 2 weeks, tubular dentin matrix was deposited on the surface of the aligned cells. Scanning electron microscopy showed that the thickness of newly formed tubular dentin was consistent. DSP and DMP-1 were expressed in columnar cells, tubular matrix and the dental papillae cells adjacent to the filter., Conclusions: The millipore filter combined with TGF-β(1) could effectively recruit progenitors onto its surface and induce odontoblast differentiation, secrete matrix in a homogenous manner, leading to dentinogenesis.

Purpose: To assess the efficacy of a novel stannous-containing dentifrice in the reduction of dentin hypersensitivity when compared to a marketed positive control dentifrice., Methods: An 8-week, single-center, randomized, parallel group, two-treatment, double-blind clinical study was conducted in a generally healthy adult population with moderate thermal and tactile dentin hypersensitivity. A total of 60 adults were enrolled into the study. Participants were stratified at baseline by age, gender, and cold air sensitivity scores, and randomly assigned to either an experimental stannous-containing sodium fluoride dentifrice or a marketed potassium nitrate positive control. Brushing was supervised on site after baseline and Week 4 examinations. All other product usage was unsupervised. Subjects brushed 2 minutes twice daily. At baseline, Week 4 and Week 8, efficacy outcomes were assessed for tactile sensitivity via the Yeaple Probe, and for thermal sensitivity with air-blast/SchiffAir Index., Results: Fifty-eight subjects completed all evaluations. Both the experimental stannous-containing and positive control dentifrices provided significant (P< 0.05) reductions in both tactile and thermal dentin hypersensitivity compared to baseline at both Weeks 4 and 8. There were no significant differences in Yeaple Probe or Schiff Air Index results between the dentifrices with either efficacy measurement at Week 4 and Week 8 (P > or = 0.5375).

Objective: To establish an in vitro model for the apatite crystal mineralization. To evaluate the influences of bovine serum albumin (BSA) and fluoride to the mineralization of apatite crystal., Methods: The model was constructed using cation selective membrane (CMV) and dialysis membrane. Double distilled water (DDW), BSA, 5, 20, 100 mg x L(-1) fluoride were added into the reaction space of the model. Reaction was carried out at 37 degrees C for 3 days under gentle stirring. The crystals were identified by scanning electron microscope (SEM) and X-ray diffraction (XRD)., Results: The model was established successfully. When DDW and BSA were added respectively, the main component of the deposit was octacalcium phosphate (OCP), but the shape and size of the crystals differs from each other. When fluoride with different concentration were added, the main component of the crystal turned to rod-like and prism-like fluoroapatite (FAP) crystal. The size and crystallinity of the FAP increased with the increase of the fluoride concentration., Conclusion: It is an effective way to evaluate the influence factors of the apatite crystal mineralization by using the in vitro model.

Objective: To construct luxS mutant aften luxS gene of Streptococcus mutans (S. mutans) was knocked out, and examine their ability of biofilm formation., Methods: A recombinant plasmid containing the flanking fragment of luxS of S. mutans was transformed into S. mutans UA159, and selected by brain heart infusion (BHI) agar medium with kanamicin. The luxS mutant further confirmed via polymerase chain reaction (PCR) and the autoinducer-2 (AI-2) bioluminescence assay of Vibrio harveyi (V. harveyi), and ability of luxS mutant and S. mutans UA159 biofilm formation was examined in different phases, in BHI medium with 1% sucrose and 1% glycose by scanning electron microscopy (SEM)., Results: LuxS-deficient S. mutans strains were successfully constructed. Compared with S. mutans UA159, the luxS mutant maintained in BHI medium containing 1% sucrose displayed an apparent defect in biofilm formation, while they showed no significant deviation in BHI medium containing 1% glycose., Conclusion: luxS gene in S.mutans can play a role in dental plaque biofilm formation, and the luxS gene is possible to regulate sucrose-dependent biofilm formation.

Objectives: Rural-urban disparities in health remain a major focus of concern. This population-based study examined the performance of Taiwan's universal healthcare system in reducing rural-urban disparities in health, through better accessibility. Changes in the rates of ruptured appendicitis were compared between residents of remote and non-remote areas in Taiwan, under the National Health Insurance (NHI) programme., Methods: We identified all 128,930 patients undergoing appendectomy in Taiwan between 1996 and 2001. The NHI inpatient files, enrolment files, major disease files, hospital registry and the household registry were linked to provide comprehensive individual and hospital information. Probit regression analyses were used to obtain adjusted estimates., Results: During the first 3 years, although the differences between the remote and non-remote areas were apparent, they were seen to be narrowing. This downward trend continued, and, since 1999, few discernible differences have been observed. After adjusting for individual and hospital characteristics, over time, the ruptured appendix rate among remote area residents was seen to be decreasing significantly faster (1.1%) than among non-remote area residents. More specifically, the children showed a substantially steeper narrowing trend (3.3%) in rural-urban disparities, than did adults., Conclusions: Our findings have shown a significant narrowing of health disparities between remote and non-remote populations, resulting from free access to care and more healthcare provision in remote areas under the NHI programme; particular success has been observed in rural children. Although certain disparities still exist, Taiwan's universal healthcare system has effectively reduced rural-urban disparities in access to care and in ultimate health outcomes.