Search

The computational fluid dynamics-discrete element coupling method is used to simulate the suspension behavior of solid particles in a stirred tank, and the motion trajectories and collision motions of millions of particles are analyzed. These particles have complex interactions with the liquid and the rotating impeller. In this article, we introduce a slip grid method, which is an important method to realize the CFD-DEM coupling. We discuss the influence of liquid flow on the trajectory of solid particles, and analyze the relationship between the eight physical properties of solid particles. It can be concluded that the CFD-DEM coupled approach provides a theoretical way to understand the physics of particle movement in micro- to macro-scales in the solid suspension of a stirred tank. [ABSTRACT FROM AUTHOR]

This paper proposes a practical split-window algorithm (SWA) for retrieving land surface temperature (LST) from Landsat-8 Thermal Infrared Sensor (TIRS) data. This SWA has a universal applicability and a set of parameters that can be applied when retrieving LSTs year-round. The atmospheric transmittance and the land surface emissivity (LSE), the essential SWA input parameters, of the Landsat-8 TIRS data are determined in this paper. We also analysed the error sensitivity of these SWA input parameters. The accuracy evaluation of the proposed SWA in this paper was conducted using the software MODTRAN 4.0. The root mean square error (RMSE) of the simulated LST using the mid-latitude summer atmospheric profile is 0.51 K, improving on the result of 0.93 K from Rozenstein (2014). Among the 90 simulated data points, the maximum absolute error is 0.99 °C, and the minimum absolute error is 0.02 °C. Under the Tropical model and 1976 US standard atmospheric conditions, the RMSE of the LST errors are 0.70 K and 0.63 K, respectively. The accuracy results indicate that the SWA provides an LST retrieval method that features not only high accuracy but also a certain universality. Additionally, the SWA was applied to retrieve the LST of an urban area using two Landsat-8 images. The SWA presented in this paper should promote the application of Landsat-8 data in the study of environmental evolution. [ABSTRACT FROM AUTHOR]

Both crystal packing and molecular size have strong influences on the charge mobility for organic semiconductors. The crystal structures for oligothiophene ( nT) can be roughly classified into two types: the Z= 2 (two molecules in one unit cell) or high temperature (HT) phase and the Z= 4 or low temperature (LT) phase. Through first-principles calculations within the Marcus electron transfer theory coupled with random walk simulation for room temperature charge diffusion constants, we found that the hole mobility of the HT phase is about 3–4 times larger than that of the LT phase because the molecular packing in the HT phase favors the hole transfer (i.e., the frontier orbital wave function phases of the dimer are constructive, which tends to maximize the overlap), while for the LT phase, the molecules are packed in a position that reduces the intermolecular orbital overlap due to phase cancellation. As the molecular size increases from 2T to 8T, the hole mobility tends to increase because the reorganization energy decreases with the chain length. [ABSTRACT FROM AUTHOR]

BACKGROUND Roxadustat is an oral hypoxia-inducible factor prolyl hydroxylase inhibitor that stimulates erythropoiesis and regulates iron metabolism. Additional data are needed regarding the effectiveness and safety of roxadustat as compared with standard therapy (epoetin alfa) for the treatment of anemia in patients undergoing dialysis. METHODS In a trial conducted in China, we randomly assigned (in a 2:1 ratio) patients who had been undergoing dialysis and erythropoiesis-stimulating agent therapy with epoetin alfa for at least 6 weeks to receive roxadustat or epoetin alfa three times per week for 26 weeks. Parenteral iron was withheld except as rescue therapy. The primary end point was the mean change in hemoglobin level from baseline to the average level during weeks 23 through 27. Noninferiority of roxadustat would be established if the lower boundary of the two-sided 95% confidence interval for the difference between the values in the roxadustat group and epoetin alfa group was greater than or equal to -1.0 g per deciliter. Patients in each group had doses adjusted to reach a hemoglobin level of 10.0 to 12.0 g per deciliter. Safety was assessed by analysis of adverse events and clinical laboratory values. RESULTS A total of 305 patients underwent randomization (204 in the roxadustat group and 101 in the epoetin alfa group), and 256 patients (162 and 94, respectively) completed the 26-week treatment period. The mean baseline hemoglobin level was 10.4 g per deciliter. Roxadustat led to a numerically greater mean (±SD) change in hemoglobin level from baseline to weeks 23 through 27 (0.7±1.1 g per deciliter) than epoetin alfa (0.5±1.0 g per deciliter) and was statistically noninferior (difference, 0.2±1.2 g per deciliter; 95% confidence interval [Cl], -0.02 to 0.5). As compared with epoetin alfa, roxadustat increased the transferrin level (difference, 0.43 g per liter; 95% Cl, 0.32 to 0.53), maintained the serum iron level (difference, 25 /xg per deciliter; 95% Cl, 17 to 33), and attenuated decreases in the transferrin saturation (difference, 4.2 percentage points; 95% Cl, 1.5 to 6.9). At week 27, the decrease in total cholesterol was greater with roxadustat than with epoetin alfa (difference, -22 mg per deciliter; 95% Cl, -29 to -16), as was the decrease in low-density lipoprotein cholesterol (difference, -18 mg per deciliter; 95% Cl, -23 to -13). Roxadustat was associated with a mean reduction in hepcidin of 30.2 ng per milliliter (95% Cl, -64.8 to -13.6), as compared with 2.3 ng per milliliter (95% Cl, -51.6 to 6.2) in the epoetin alfa group. Hyperkalemia and upper respiratory infection occurred at a higher frequency in the roxadustat group, and hypertension occurred at a higher frequency in the epoetin alfa group. CONCLUSIONS Oral roxadustat was noninferior to parenteral epoetin alfa as therapy for anemia in Chinese patients undergoing dialysis. (Funded by FibroGen and FibroGen [China] Medical Technology Development; ClinicalTrials.gov number, NCT02652806.) [ABSTRACT FROM AUTHOR]

The output window of a high-power laser system is vulnerable to damage, and this is the main limiting factor on the power scaling and structure integrity of the laser system. In endeavoring to obtain higher output powers from the laser system, the impact of the thermal and mechanical effects and the damage mechanism of the output window must be considered. In order to study these issues, a thermal model of the laser window is established based on the heat transfer and thermoelastic theories, and the expressions for the transient thermal and mechanical stress distributions of the output window are deduced in terms of the integral-transform method. Taking the infrared quartz window material as an example, the temperature and mechanical field distributions of a high-power all-solid-state 2-µm laser system window are simulated, and the laser-induced damage mechanism is deeply analyzed. The calculation results show that the laser window-induced damage is mainly caused by melting damage when the temperature exceeds the melting point of the material. The presented theoretical analysis and numerical simulation results are significant for the design and optimization of high-power laser windows. [ABSTRACT FROM AUTHOR]