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[en] Objective: To compare the efficacy and side-effects of intensity-modulated radiotherapy (IMRT) and conventional radiotherapy in treatment of nasopharyngeal carcinoma (NPC) involving cervical vertebrae. Methods: Twenty-four patients of NPC with cervical vertebra involvement underwent IMRT with the dose to tumor target of 72-74 Gy divided into 33 fractions (IMRT group), and 29 patients underwent conventional radiotherapy with the total dose to tumor target of 68-74 Gy/34-37 fractions (2D-CRT group). All the 53 cases accepted platinum-based concurrent chemotherapy of cisplatin plus fluorouracil and 4-6 cycles of adjuvant chemotherapy after the radiotherapy. Follow-up was conducted for 6 months to more than 7 years. Results: The 3-and 5-year overall survival (OS) rates of the IMRT group were 87.7% and 65.5% respectively, both significantly higher than those of the 2D-CRT group (45.5% and 9.1% respectively, χ2 = 6.89, P < 0.05), and the 3-and 5-year local progression-free survival (LPFS) rates of the IMRT group were 87.4% and 49.4% respectively, both significantly higher than those of the 2D-CRT group (69.9% and 9.4% respectively, χ2 = 13.26, P < 0.05), and there were no significant statistical differences in the 3-, and 5-year distant metastasis-free survival (DMFS) rates (94.4% vs 40.8% and 79.8% vs 30.4% respectively, χ2 = 2.29, P > 0.05) between two groups. Analysis showed N stage (χ2 = 8.53, P < 0.05) and radiotherapy protocol (χ2 = 8.02, P < 0.05) as the independent prognostic factors for OS and LPFS. The incidence of grade 2 and 3 xerostomia of the IMRT group was 29.17%, significantly lower than that of the 2D-CRT group (65.52%, χ2 = 7.11, P < 0.05). Whereas, there were no significant statistical differences between these 2 groups in the incidence rates of acute irradiation mucositis and bone marrow suppression. Conclusions IMRT improves the local progression-free survival and overall survival and reduces the incidence of grade 2 and 3 radiation-induced xerostomia in local advanced NPC with cervical vertebra involvement more effectively than conventional radiotherapy. However, it fails to reduce the incidence of distant metastasis. (authors)
[en] Multi-unit air conditioners (MUACs) are widely used in light commercial buildings and residential buildings due to their higher thermal comfort and energy efficiency. To investigate the transient characteristics of MUACs, a dynamic simulation model with the framework of two-phase fluid network is developed. The state-space forms are used to model the system and components, and the component submodels are embedded in the fluid network model, which makes it possible to update the system model and components submodels independently. In the model of state-space form, the differentials are obtained by taking the inverse of coefficient matrix, and then the state parameters are calculated by integrating the differentials with time. The simulation outputs are compared with the experimental data in the step changes of the compressor speed and electronic expansion valve openings. The comparison shows that the proposed model can catch the dynamic characteristics of MUACs with high accuracy. Therefore, it can be used as an effective tool to analyze the transient performance and optimize the control algorithm of MUACs. - Highlights: ► A dynamic model is developed for multi-unit air conditioners (MUAC). ► The model is built in the two-phase fluid network for different MUACs. ► State-space method model is built for evaporators, condensers and MUACs. ► The component submodels are embedded in the fluid network model for easy updating. ► The model can catch the dynamic characteristics of MUACs with high accuracy.
[en] With the aim of developing a new tumor imaging agent, the IFLLWQR (Ile-Phe-Leu-Leu-Trp-Glu-Arg, IF7) was conjugated with 1, 4, 7-triazacyclononane-N, N', N'-triacetic acid (NOTA) and labeled with 68Ga. In the optimal conditions, the whole radio-synthesis was accomplished within 20 min. The decay-corrected radiochemical yield was more than 92 %. The radiochemical purity of 68Ga-NOTA-IF7 was more than 95 %. MicroPET studies showed a high tumor uptake at 15 min post-injection with 7.52 ± 0.16 %ID/g. The ratios of tumor to muscle uptake were 20.61 ± 0.31, 13.14 ± 0.21, 2.39 ± 0.12 at 15 min, 30 min and 60 min post-injection, respectively. 68Ga-NOTA-IF7 is a promising radiopharmaceutical for tumor imaging. (author)
[en] Some ionic liquids have dehumidification capacity and are non-corrosive to metals. Based on the Finite Difference Method, the heat and moisture transfer model of the counter-flow dehumidifier was established. Using this model, the dehumidification capacity of one kind of ionic liquids 1-Ethyl-3-methylimidazolium Tetrafluoroborate ([EMIM]BF4) and traditional desiccant lithium bromide (LiBr) was compared in equivalent conditions. The results show that the dehumidification performances of the two solutions both improve with the increase of air flow rate, solution flow rate and air humidity. Even though the dehumidification rate of [EMIM]BF4 is a little lower than that of LiBr, such difference could be reduced by increasing the mass concentration of [EMIM]BF4. Meanwhile, compared with traditional desiccants, [EMIM]BF4 solution has significantly lower corrosion to metals and does not crystallize at high mass concentration, which render it a possible substitute of existed desiccants in liquid desiccant air conditioning systems. - Highlights: → The paper researched on using [EMIM]BF4 solution as desiccant in the liquid desiccant air conditioning system by simulation. → By comparing the dehumidification performance of [EMIM]BF4 solution with traditional desiccant LiBr solution, it confirms the feasibility of using [EMIM]BF4 as desiccant. → [EMIM]BF4 solution has significantly lower corrosion of metals and does not crystallize at high mass concentration, which make it a possible substitute of existed desiccants.
[en] It is essential to ensure the stability for the normal operation of refrigeration systems. This paper reviews the researches on the theory and solutions of the instability of refrigeration systems. The instability of refrigeration systems includes two aspects: the two-phase flow instability in refrigeration system, the instability on refrigeration system control characteristics. As an inherent characteristic of two-phase evaporating flow, several separate explanations for the formation of oscillation of mixture-vapor transition point in the evaporation process by different scholars had been given but there is no general explanation till now. The investigation of instability on refrigeration system control characteristics focused on both static and dynamic researches. The minimum stable signal line theory, as a very important finding for the static instability of the evaporator and thermal expansion valve control loop, presented the different result to other researches. Dynamic researches on simulation and frequency-domain analysis provided various means for forecast and validation with considerable precision while their application range was still confined. With the development of variable capacity compressor and electronic expansion valve, further researches should be carried out to analyze the instability of the variable capacity refrigeration system with considering the influence of parameter coupling and control algorithm.
[en] A novel spray cooling system integrated in the refrigeration circuit is proposed and its performance is investigated experimentally. In this system, the inverter compressor is used to replace the pump in common spray systems, the nozzle plays the role of atomization and throttling, and the spray chamber has function of the evaporator. The nozzle inlet pressure, the evaporation pressure and the degree of subcooling at nozzle inlet are all adjusted to testify the performance of the novel system in experiments. With 60 W/cm2 heat flux, the heat transfer coefficient observed is higher than 30 000 W/m2 K. The critical heat flux up to 110 W/cm2 is obtained, and heater surface temperature is only 31.5 °C under the heat load. Keeping the nozzle inlet pressure (Pin = 390 kPa), the evaporation pressure (Pe = 180 kPa) and the heat flux (q = 72 W/cm2) constant, the experimental results show that the optimal subcooling degree is 5.8 °C. The novel spray cooling system developed in this paper has simple structure and convenient regulation, and its performance can meet the heat removal requirements of most electronic devices in actual applications.
[en] Highlights: • Three parameters are used to evaluate the startup performance. • The startup is faster and overshoot is larger when the distribution is more uneven. • Heating on one evaporator with same Q with the other makes transition time longer. • Heating on one evaporator with same Q with the other makes the overshoot smaller. • Transition time is about twice as much as peak time when peak time exists. - Abstract: Loop thermosyphon with multiple evaporators is a promising device in multi-source heat transfer. The startup performance is very important for its thermal control ability. In this paper, the effect of heating power distribution on the startup of a loop thermosyphon with dual evaporators is investigated experimentally. The startup time and stationarity under different power distributions are analyzed utilizing three parameters: peak time, transition time and temperature (pressure) overshoot. The results show that the startup process is faster and the overshoot of pressure and temperature is larger when the distribution is more uneven; Heating on one evaporator with the same heating power with the other evaporator makes the startup process longer while it makes the overshoot smaller or even disappear; The transition time is approximately twice as much as the peak time when the peak time exists.
[en] Wave energy is one of the most promising renewable energy for power generation. This research develops a novel power take-off methodology to surmount the problems associated with mooring, seawater corrosion and access for maintenance in conventional WEC (wave energy converters) with direct-driven linear generators. Its prototype consists of two bodies, the floating body acting as a buoy to extract the wave energy, while the inner body undergoes a forced oscillation, whose relative motion generates the electronic power. Its feasibility is investigated theoretically by coupling the dynamics of the wave, the floating and the inner bodies and the electromagnetic characteristics of the linear generator. As a result, the generator can induce a highly sinusoidal voltage. Furthermore, the performance of the system is investigated in detail under different conditions. The results show that, a resonance has been achieved in the case with the spring constant of 12,633 N/m, with a maximum power capture ratio of 57%. The performance of the system is shown to be sensitive to the load resistance, the wave height, and the spring constant. - Highlights: • A fully floating wave energy converter utilizing the relative motion is proposed. • The generator is fixed in an enclosed cavity without contact with the seawater. • A coupled dynamic and electromagnetic theoretically model has been established. • The linear generator in the WEC can induce a nearly sinusoidal voltage. • A resonance has been achieved in the WEC with a maximum power capture ratio of 57%.
[en] In study, we proposed a simple yet fast optical sensing motif based on thimbleful of polyvinyl alcohol (PVA) infiltrated photonic crystal (PC), which allows for high efficiency in vapor sensing through changes in their inter-layer space. Linear response to a broad dynamic range of vapor concentration was realized. Ultrafast response time (<1 s) and excellent recyclability were also demonstrated. Selective response to a vapor was exhibited, reflecting well the characteristic sorption properties of PVA, with which colorimetric reporting was readily achieved. These substantial improvements in performance are attributed to the efficacy of signal transduction and the enhanced signal transduction because of thimbleful PVA infiltrated space between adjacent SiO2 nanospheres.
[en] Highlights: • A real-time leak detection method is developed for ammonia pipeline in cold storage. • A locating algorithm based on pressure difference profile is provided. • This method is validated by R22 and ammonia leak experiments. • The minimum detectable leak ratio is 1% for R22 and 4% for ammonia. • The location estimating errors are −27% ~ 17% for R22 and −27% ~ 27% for ammonia. - Graphical Abstract: - Abstract: Leakage from pressurized liquid ammonia pipeline has been a serious problem in large commercial cold storages because it might release large amount of liquid ammonia and without safety supervision in daily operations. The present paper shows a detection method for a pressurized liquid ammonia pipeline with a leak. The variations of pressure, flow rate and pressure difference profile are studied. A leak indicator (σ), proposed with the one-dimensional steady-state flow model, is used to detect the leak occurrence by comparing it with a threshold value (σ_L_e). A locating algorithm based on pressure difference profile along the pipeline is also proposed, which has considered the effect of the static pressure increase at the leak point. Experiments on different leak positions and ratios from liquid R22 and ammonia pipelines are carried out to validate this method. It is found that, with a relatively low false alarm rate (as three percent), the minimum detectable leak ratio reached 1% for the R22 pipeline and 4% for the ammonia pipeline. The locating errors are between −27% ~ 17% for R22 pipeline and −27% ~ 27% for ammonia pipeline.