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[en] We report on the synthesis of Nd:YAG nanoparticles by the coprecipitation technique and the optimum conditions for the processing of transparent ceramics. The powders prepared by the coprecipitation technique display significantly less agglomeration of crystallites, indicating higher sinterability. The crystallite size dependence on the calcinations temperature suggests the optimum temperature of 1100 deg. C, at which phase purity of the YAG nanopowder with the highest sinterability can be obtained. We have demonstrated that the optimum temperature for the vacuum-sintering is about 1785 deg. C for the uniaxially pressed samples to obtain transparent ceramic with uniform particle size of about 5-7 μm, and above this temperature, enormously large grain growth occurs, and facilitates large pores formation in the intergrain region that makes the ceramic fragile at the grain boundary
[en] Fine particulate matter (less than 2.5 μm in aerodynamic diameter; PM_2_._5) pollution poses a major environmental threat in Greater Houston due to rapid economic growth and the numerous PM_2_._5 sources including ports, vehicles, and the largest petrochemical industry in the United States (U.S.). Our objectives were to estimate the short-term associations between the PM_2_._5 components and mortality during 2000–2011, and evaluate whether these associations have changed over time. A total of 333,317 deaths were included in our assessment, with an average of 76 deaths per day. We selected 17 PM_2_._5 components from the U.S. Environmental Protection Agency's Chemical Speciation Network, and then applied Poisson regression models to assess the associations between the PM_2_._5 components and mortality. Additionally, we repeated our analysis for two consecutive periods: 2000–2005 and 2006–2011. Interquartile range increases in ammonium (0.881 μg/m"3), nitrate (0.487 μg/m"3), sulfate (2.245 μg/m"3), and vanadium (0.004 μg/m"3) were associated with an increased risk in mortality of 0.69% (95% confidence interval (CI): 0.26, 1.12%), 0.38% (95% CI: 0.11, 0.66%), 0.61% (95% CI: 0.15, 1.06%), and 0.58% (95% CI: 0.12, 1.04%), respectively. Seasonal analysis suggested that the associations were strongest during the winter months. The association between PM_2_._5 mass and mortality decreased during 2000–2011, however, the PM_2_._5 components showed no notable changes in mortality risk over time. Our study indicates that the short-term associations between PM_2_._5 and mortality differ across the PM_2_._5 components and suggests that future air pollution control measures should not only focus on mass but also pollutant sources. - Highlights: • PM_2_._5 concentrations were associated with increased mortality risk. • A few major PM_2_._5 components were associated with increased mortality risk. • Associations were generally strongest in winter in Greater Houston. • Effect estimates of PM_2_._5 mass had reduced from 2000–2005 to 2006–2011.
[en] Background: Flow induced vibration (FIV) is one of the main cause of steam generator tubes failure. Flow induced vibration of steam generator tubes shall be analyzed with the design of steam generator. Small-scale gaps exist between tubes and tube support plates (TSP) or anti-vibration bars (AVB). These gaps make the system non-linear. Purpose: Linear equivalence to the gaps shall be performed in the linear FIV analysis. Methods: This paper analyzes the influence of tube gaps on the dynamic characteristics of tubes with theoretical and simulation methods. Results: According to the analyses, the influence of gaps on tubes is similar to that of simple supports. Conclusions: Simple supports can be used to substitute gaps in the linear analysis for flow induced vibration. (author)
[en] Background: In recent years some reactors have experienced significant steam dryer cracking. In some cases, this cracking has necessitated unplanned outages to implement steam dryer repairs and has also resulted in de-rated operation of the affected units. Initial inspection showed it was likely that steam dryer had been damaged by high cycle fatigue due to flow-induced acoustic resonance in the main steam lines. Because of the complexity and acoustic-structure coupling effect, scale model test is adopted to research the mechanism of acoustic fatigue. Purpose: This paper describes the derivations of scaling laws observed to control the system response for phenomena considered to be significant in the real plants. Methods: Basic governing equations of elasticity and acoustics are written in non-dimensional form, non-dimensional groups are defined and derived. Results: Using the reference values in the real plants, the scaling laws and scaling relationships are derived and recognized to enable conversion of model data into real plant predictions. Conclusions: Successful model testing can be achieved if these significant parameters are preserved in the model scale. (author)
[en] Various methods are presented for measuring the pellet length in the cladding tube (zirconium tube) during the loading process of the preparation of single rod of nuclear fuel assembly. These methods are used in former Soviet Union, west European countries and China in the manufacturing of nuclear power plant element. Different methods of dynamic measurement by using mechanics, optics and electricity and their special features are analysed and discussed. The structure and measuring principle of a developed measuring device,and its measuring precision and system deviation are also introduced. Finally, the length of loaded pellets is checked with analog pellets. The results are as expected and show that the method and principle used in the measuring device are feasible. It is an ideal and advanced method for the pellet loading of single cladding tube. The principle mentioned above can also be used in other industries
[en] Highlights: • Sn (core)–Al (shell) nanocomposite thin film is prepared by magnetron sputtering method. • The effect of Al on the structure and electrochemical performance has been investigated. • Improved electrochemical performance is obtained. - Abstract: In this paper, we report on the preparation of Sn (core)–Al (shell) nanocomposite thin films by co-sputtering Sn target and Al target, and their application as anode of lithium-ion batteries. Instrumental analyses of X-ray diffraction, energy dispersive X-ray analysis, scanning electron microscopy, and transmission electron microscope have been used to characterize the structure and morphology. The results reveal that the thin film is composed of core–shell structure with Sn nanoparticle core and Al amorphous shell. Furthermore, measurements of charge–discharge, cyclic voltammetry and electrochemical impedance spectroscopy have been employed to characterize the electrochemical performance of Sn–Al film. The Sn–Al thin film with 18 wt% Al delivers high capacities of 822, 460 and 313 mA h g"−"1 in the second 2nd, 60th and 200th cycles, respectively. Meanwhile, a discharge capacity of 420 mA h g"−"1 is obtained at 3000 mA g"−"1. The excellent electrochemistry performance is owing to the core–shell structure in which Al shell can alleviate the expansion of volume of Sn particles and restrain the aggregation of Sn particles. The results indicate that Sn–Al thin film is a promising anode for lithium-ion batteries
[en] Proteins play important roles in biological and cellular processes. The levels of proteins can be useful biomarkers for cellular events or disease diagnosis, thus the method for sensitive and selective detection of proteins is imperative to proteins express, study, and clinical diagnosis. Herein, we report a “signal-on” platform for the assay of protein based on binding-induced strategy and photoinduced electron transfer between Ag nanoclusters and split G-quadruplex-hemin complexes. By using biotin as the affinity ligand, this simple protocol could sensitively detect streptavidin with a detection limit down to 10 pM. With the use of an antibody as the affinity ligand, a method for homogeneous fluorescence detection of Prostate Specific Antigen (PSA) was also proposed with a detection limit of 10 pM. The one-step and wash-free assay showed good selectivity. Its high sensitivity, acceptable accuracy, and satisfactory versatility of analytes led to various applications in bioanalysis. - Highlights: • AgNCs have great potential for application in biomedicine. • Binding of two affinity ligands can result in binding-induced DNA assemblies. • PET can be happened between DNA/AgNCs and G-quadruplex/hemin complexes. • A platform for the detection of proteins was proposed by using PET and binding-induced strategy
[en] Highlights: • A micro-scale thermosyphon heat pipe technology for 3D chip cooling is proposed. • CHF for micro-scale thermosyphon can be roughly predicted by the conventional correlation. • Adding suitable SDS into R113 can significantly improve heat transfer in thermosyphon. • Adding suitable nanoparticles into R113 can further improve heat transfer in thermosyphon. - Abstract: A micro-scale thermosyphon heat pipe technology which passively utilizes 3D chip’s specific micro-channels structure as the evaporating section of the thermosyphon to form a thermosyphon boiling in micro-channels for 3D chip cooling is proposed. The maximum heat flux and heat transfer coefficient of thermosyphon boiling in micro-channels which simulated actual 3D chip structure were experimentally studied. Experiments were carried out using four kind of working liquids: two pure fluids (deionized water and R113), super-moist fluids (R113 + surfactant) and nanofluids (R113 + surfactant + CuO nanoparticles). The height and gap of channels used were in the range of 30 mm to 100 mm and 30 μm to 1 mm, respectively. Experimental results show that nanofluids can significantly enhance both the maximum heat flux and heat transfer coefficient of thermosyphon boiling in micro-channels due to super-wettability of the liquid and the formation of a porous sedimentary layer consisted of nanoparticles on the wall. The results show that the micro thermosyphon heat pipe structure is a promising technology for 3D chip cooling.
[en] Radium and radon equilibrium coefficient is an important recifying parameter for resources/reserves estimation. Starting with the the reason analysis about radium and radon balance on sandstone type uranium deposits, the authors discussed the calculation means of radium and radon equilibrium coefficient and their difference. This corrected parameter provide scientific evidence for correction of radioactivity logging, division of cut-off grade and resources/reserves estimation. (authors)
[en] In isotopes separation technologies, the centrifuge method has been the most popular technology now. Separation performance of centrifugal machines is greatly influenced by the flow field in the centrifugal machines. And the position of scoops in the centrifuges has a significant influence on the flow field. To obtain a better flow field characteristic and find the best position of scoops in the centrifuges, a position adjustable scoop system was studied. A micro stage and a linear encoder were used in the system to improve the position accuracy of the scoop. Eddy current sensors had been used in a position calibration measurement. The measurement result showed the sensitivity and stability of the position system could meet the performance expectation. But as the driving mean, the steel wire and pulley limit the control precision. On the basis of this scheme, an ultrasonic motor was used as driving mean. Experimental results showed the control accuracy was improved. This scheme laid a foundation to obtain internal flow field parameters of centrifuge and get the optimal feeding tube position. (authors)