This paper compares invasive and non-invasive voidage measurement techniques from five different Canadian laboratories for the determination of local voidage profiles in gas-fluidized beds of 104μm ...Fluid Cracking Catalyst (FCC) and 332μm silica sand in a column of 133mm i.d. A novel modular system and auxiliary components were designed and constructed to facilitate transportation to, and deployment at, different research centers. Profiles of time-averaged voidage were determined by optical fiber probes, dynamic pressure measurements, electrical capacitance tomography, X-ray computed tomography and radioactive particle tracking by researchers from different research groups. These results are compared with average measurements from pressure gradients and overall bed expansion. Results were kept separate from each other in a double-blind method. There is general, but imperfect, agreement among the different methods for average voidage for both the FCC and silica sand. Invasive probes gave similar results and scatter to non-invasive techniques.
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► A novel fluidized bed was built to ensure identical operating conditions. ► The equipment traveled to different laboratories for hydrodynamic investigation. ► Results of alternate voidage measurement techniques are directly compared. ► Invasive probes give similar voidage results to non-invasive techniques. ► This initiates a comprehensive database for future model validation.
The Li3(Mg1−xCox)2NbO6 (0.00 ≤ x ≤ 0.10) ceramics were prepared by the solid-state reaction route in this paper. The effects of Co-substitution on phase composition, microstructure and microwave ...dielectric properties of the Li3Mg2NbO6 were investigated by a variety of characterization methods. XRD patterns and Raman spectrum revealed that the all the compositions possessed orthorhombic structure with the space group of Fddd. The Q·f values of samples sintered at 1300 °C increased from 91,600 GHz at x = 0 to 127,600 GHz at x = 0.02, which was basically attributed to the appropriate amount of Co2+. With the x value increasing from 0 to 0.10, the τf value was gradually shifted toward zero, which indicated that the ionic substitution could effectively adjust the crystal stability of the matrix. In addition, there were no significant changes in the dielectric constant and grain sizes in the Li3(Mg1−xCox)2NbO6 compositions. Out these compositions, the Li3(Mg0.98Co0.02)2NbO6 ceramic sintered at 1300 °C exhibited excellent microwave dielectric properties of ɛr = 15.22, Q×f = 127,600 GHz and τf = −3.64 ppm/°C, which made the ceramics promising for future applications.
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•Co-Substitution increased the Q·ƒ values of Li3Mg2NbO6 ceramics to 127,600 GHz.•Substitution of Mg2+ improved the τf values of ZnZrNb2O8 ceramics.•Excellent microwave dielectric properties were obtained when x = 0.02.
The Astrophysical Radiation with Ground-based Observatory at Yang Ba Jing (ARGO-YBJ) detector is an extensive air shower array that has been used to monitor the northern gamma -ray sky at energies ...above 0.3 TeV from 2007 November to 2013 January. In this paper, we present the results of a sky survey in the declination band from -10degrees to 70degrees, using data recorded over the past five years. With an integrated sensitivity ranging from 0.24 to ~1 Crab units depending on the declination, six sources have been detected with a statistical significance greater than five standard deviations. Several excesses are also reported as potential gamma -ray emitters. The features of each source are presented and discussed. Additionally, 95% confidence level upper limits of the flux from the investigated sky region are shown. Specific upper limits for 663 GeV gamma -ray active galactic nuclei inside the ARGO-YBJ field of view are reported. The effect of the absorption of gamma -rays due to the interaction with extragalactic background light is estimated.
Abstract
Laser directed energy deposition (LDED) process has unique advantage in rapid forming of large-sized metal components, gradient material/structural components, or repairing/remanufacturing ...worn parts. However, the high residual stress and strong anisotropy in mechanical properties of the as-deposit components limit the application of LDED technology in the manufacturing of key structural components. To overcome these problems, various hybrid additive manufacturing (HAM) technologies have been developed, such as plastic deformation, ultrasonic or magnetic field assisted LDED processes to improve the quality and the mechanical properties, where these coupled processes are carried out either simultaneously or cyclically with the LDED process. The hybrid additive manufacturing, while retaining the advantages of individual forming process, avoids the mutual interference between each process and reducing the adverse effects generated if used separately. Hybrid additive manufacturing processes fundamentally change the underlying physical mechanisms of molten pool dynamics, microstructural evolution, temperature and thermal stress gradient in additive manufacturing, thereby optimizing the microstructure and performance of the manufactured components. In this paper, the key technical features of the hybrid additive manufacturing process coupled with plastic deformation were described in details, and the resulting differences in microstructure, residual stress, and mechanical properties of the prepared samples were systematically analyzed. The developing trend of hybrid additive manufacturing processes in coupling mechanisms, parameter optimization, and equipment have been discussed.
The rock salt structured Li2Mg1-xZnxTiO4 ceramics were prepared by the conventional solid-state method. X-ray diffraction, bond energy and Raman spectra were employed to investigate the crystal ...structure and polarization characteristics of the ceramics. With the x value increasing from 0 to 0.5, the dielectric constant of Li2Mg1-xZnxTiO4 gradually increased from 15.36 to 18.42, which was attributed to the higher polarizability of zinc ions. The variation trend of the polarizability was also in accordance with that of Raman vibration modes. The quality factor of specimens initially increased and then significantly decreased with the increase in Zn2+ substitution, which could be explained in the variation of packing fraction. In addition, the temperature coefficient of resonant frequency showed a tendency of decrease with the decreasing bond energy, implying that the substitution of Zn2+ influenced the crystal stability of Li2MgTiO4. An appropriate amount of zinc substitution effectively improved the dielectric permittivity and decreased the dielectric losses of the matrix. The Li2Mg0.9Zn0.1TiO4 ceramics sintered at 1350 °C possessed excellent microwave dielectric properties with εr = 16.20, Q·ƒ = 145,200 GHz and τf = −4.03 ppm/°C, which made these ceramics promising for future applications.
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•Substitution of Zn2+ enhanced the dielectric permittivity of Li2MgTiO4.•Higher polarizability was related to lower Raman shift in the system.•Individual bond energy predicted the variation of τf value.•Li2Mg0.9Zn0.1TiO4 had good property with εr = 16.20, Q·ƒ = 145,200 GHz and τf = −4.03 ppm/°C.
We report on a measurement of thermal neutrons, generated by the hadronic component of extensive air showers (EAS), by means of a small array of EN-detectors developed for the PRISMA project (PRImary ...Spectrum Measurement Array), novel devices based on a compound alloy of ZnS(Ag) and 6LiF. This array has been operated within the ARGO-YBJ experiment at the high altitude Cosmic Ray Observatory in Yangbajing (Tibet, 4300 m a.s.l.). Due to the tight correlation between the air shower hadrons and thermal neutrons, this technique can be envisaged as a simple way to estimate the number of high energy hadrons in EAS. Coincident events generated by primary cosmic rays of energies greater than 100 TeV have been selected and analyzed. The EN-detectors have been used to record simultaneously thermal neutrons and the air shower electromagnetic component. The density distributions of both components and the total number of thermal neutrons have been measured. The correlation of these data with the measurements carried out by ARGO-YBJ confirms the excellent performance of the EN-detector.
Purpose. To study the relationship between surface membrane-bound APRIL and ITP. Methods. The peripheral blood of all subjects, 50 patients diagnosed with ITP and 25 healthy controls, was collected. ...Flow cytometry was used to detect the expression of membrane-bound APRIL on immune cells and platelets. ELISA was used to detect the content of soluble APRIL in plasma. Results. Membrane-bound APRIL was only expressed on the surface of platelets in both ITP patients and controls. APRIL expression on the platelet surface was significantly lower in newly diagnosed (P<0.001) and chronic (P<0.001) ITP patients than in controls. Platelet surface APRIL level was significantly enhanced in patients with complete remission after treatment (P=0.02) but not in those with no response after treatment. Platelet surface APRIL level in ITP patients was negatively correlated with serum APRIL level (r=−0.09765, P=0.0424). Conclusions. Platelet surface APRIL may play a key immunoregulative role. Platelet surface APRIL is likely to be one source of the excessive serum APRIL in ITP patients. The effectiveness of treatment may be measured by determining the platelet surface APRIL levels in ITP patients.
Wolframite-structured Zn1−xNixZrNb2O8 (0 ≤ x ≤ 0.1) ceramics were synthesized by the conventional solid-state method. The effects of Ni2+ substitution on sintering characteristic, crystal structure, ...and microwave dielectric properties of ZnZrNb2O8 samples were systematically studied. The relationship among bond ionicity, lattice energy, thermal expansion coefficient and microwave dielectric properties was also investigated by the complex chemical bond theory. The dielectric constant of Zn1−xNixZrNb2O8 ceramics sintered at 1150 °C slightly decreases from 28.06 to 26.35 with the increasing Ni2+ content, which can be explained by the variation of bond ionicity and polarizability. Raman scattering spectra also reveal that the increase in Ni2+ content leads to the shift in all the vibration modes and the variation of ionicity in NbO bond. The Q·f values increases from about 40,000 to 60,000 GHz with the increasing Ni2+ content, which can be explained by the variation of lattice energy. As for τf value, it is shifted to positive direction, which can be explained in term of the variation in Nb-site bond energy. In addition, the thermal expansion coefficient plays little effect on the temperature stability of ceramics. Typically, the Zn0.96Ni0.04ZrNb2O8 samples sintered at 1150 °C exhibit excellent properties with εr = 27.10, Q·f = 62,700 GHz and τf = −14.72 ppm/°C.
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•Zn1−xNixZrNb2O8 ceramics were prepared by solid-state method.•Complex chemical bond theory was used to study microwave dielectric properties.•εr was correlated with NbO bond ionicity as well as polarizability.•Q·f was correlated with lattice energy of NbO bond.•Excellent properties with εr = 27.10, Q·f = 62,700 GHz and τf = −14.72 ppm/°C when x = 0.04
Individuals with impaired glucose tolerance (IGT) have a high risk of developing NIDDM. The purpose of this study was to determine whether, diet and exercise interventions in those with IGT may delay ...the development of NIDDM, i.e., reduce the incidence of NIDDM, and thereby reduce the overall incidence of diabetic complications, such as cardiovascular, renal, and retinal disease, and the excess mortality attributable to these complications. In 1986, 110,660 men and women from 33 health care clinics the city of Da Qing, China, were screened for IGT and NIDDM. Of these individual, 577 were classified (using World Health organization criteria) as having IGT. Subjects were randomized by clinic into a clinical trial, either to a control group or to one pf three active treatment groups diet only, exercise only or diet plus exercise. Follow-up evaluation examination were conducted at 2-year intervals over a year period to identify subjects who developed NIDDM. Cox's proportional hazard analysis was used to determine if the incidence of NIDDM varied by treatment assignment. The cumulative incidence of diabetes at 6 years was 67.7% (95% CI, 59.8-75.2) in the control group compared with 43.8% (95% CI, 35.5-52.3) in the diet group, 41.1% (95% CI, 33.4-49.4) in the exercise group, and 46.0% (95% CI, 37.3-54.7) in the diet-plus exercise group (P 0.05). When analyzed by clinic, each of the active intervention groups differed significantly from the control clinics (P 0.05). The relative decrease in rate of development of diabetes in the active treatment groups was similar when subjects were stratified as lean or overweight (BMI or greater than or equal to 25 kg/m2). In a proportional hazards analysis adjusted for differences in baseline BMI and fasting glucose, the diet, exercise, and diet-plus-exercise interventions were associated with 31% (P 0.03), 46% (P 0.0005), and 42% (P 0.005) reductions in risk of developing diabetes, respectively. Diet and/or exercise interve
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