Through combined theoretical and experimental efforts, the reaction mechanism of ethanol steam reforming on Rh catalysts was studied. The results suggest that acetaldehyde (CH3CHO) is an important ...reaction intermediate in the reaction on nanosized Rh catalyst. Our theoretical work suggests that the H-bond effect significantly modifies the ethanol decomposition pathway. The possible reaction pathway on Rh (211) surface is suggested as CH3CH2OH → CH3CH2O → CH3CHO → CH3CO → CH3 + CO → CH2 + CO → CH + CO → C + CO, followed by the water gas shift reaction to yield H2 and CO2. In addition, we found that the water-gas shift reaction, not the ethanol decomposition, is the bottleneck for the overall ethanol steam reforming process. The CO + OH association is considered the key step, with a sizable energy barrier of 1.31 eV. The present work first discusses the mechanisms and the water effect in ethanol steam reforming reactions on Rh catalyst from both theoretical and experimental standpoints, which may shed light on designing improved catalysts.
Context weighting is an important technology for genome compression. In this study, we discuss the relationship between the weighting of context models and the weighting of the description lengths ...corresponding to their respective context models. It indicates that weighting of context models is equivalent to the weighting of their description lengths. With these discussions, we present the weights optimization algorithm based on the minimum description length, and suggest implementing the least-square algorithm for the optimization of the weights. The proposed optimization algorithm is used in the compression of bacterial genome sequences. The experiment results indicate that by using the proposed weights optimization method, our context weighting-based genome compression algorithm can achieve better performance than context weighting-based algorithms reported in the literature.
Biased assessment of tillage impacts on soil organic carbon (SOC) sequestration are often associated with a lack of information on the initial level of SOC stocks. The present study reported the ...changes in SOC concentrations and stocks following 10-year different tillage practices relative to the initial SOC levels. The tillage trial included no tillage (NT), ridge tillage (RT) and mouldboard plough (MP) on a Black soil (Hapludolls) in Northeast China. Results showed that tillage, soil depth and time significantly affected SOC concentration and SOC stock. Tillage and crop residue retention had great impacts on the SOC concentrations in the top 0·1 m layer. Compared with MP and NT, RT resulted in higher SOC concentration and SOC stock in the plough layer (0–0·2 m), which became more obvious with time. The soil under NT and RT had higher stratification ratios (SR) of SOC (SR, the ratio of SOC concentration in 0–0·05 m to that in 0·1–0·2 m) than under MP. Significant positive and nearly identical linear relationships between the SR of SOC and the duration of tillage practices occurred for both NT and RT soils; the increased SR in NT resulted from both SOC increase in surface and SOC decrease in subsurface soils, but in RT, the increased SR was only from a substantial SOC increase in surface soil. Accordingly, the present study highlights that RT was more helpful than NT in carbon sequestration for the studied Black soil in Northeast China.
This multi-centre retrospective study was designed to investigate the risk factors for infection with imipenem-resistant Pseudomonas aeruginosa in neonatal intensive care units (NICUs) in south ...China. All patients with confirmed P. aeruginosa infection from eight NICUs in south China were divided into two groups: imipenem-susceptible P. aeruginosa and imipenem-resistant P. aeruginosa. Data were analysed using Chi-squared test and logistic regression. In total, 188 medical records were reviewed. On multi-variate logistic analysis, the only independent risk factor was imipenem treatment within two weeks of isolation of P. aeruginosa (odds ratio 6.409, 95% confidence interval 1.926–21.333).
The refraction and reconnection of internal solitary waves (ISWs) around the Dongsha Atoll (DSA) in the northern South China Sea (SCS) are investigated based on spaceborne synthetic aperture radar ...(SAR) observations and numerical simulations. In general, a long ISW front propagating from the deep basin of the northern SCS splits into northern and southern branches when it passes the DSA. In this study, the statistics of Envisat Advanced SAR (ASAR) images show that the northern and southern wave branches can reconnect behind the DSA, but the reconnection location varies. A previously developed nonlinear refraction model is set up to simulate the refraction and reconnection of the ISWs behind the DSA, and the model is used to evaluate the effects of ocean stratification, background currents, and incoming ISW characteristics at the DSA on the variation in reconnection locations. The results of the first realistic simulation agree with consecutive TerraSAR‐X (TSX) images captured within 12 h of each other. Further sensitivity simulations show that ocean stratification, background currents, and initial wave amplitudes all affect the phase speeds of wave branches and therefore shift their reconnection locations while shapes and locations of incoming wave branches upstream of the DSA profoundly influence the subsequent propagation paths. This study clarifies the variation in reconnection locations of ISWs downstream of the DSA and reveals the important mechanisms governing the reconnection process, which can improve our understanding of the propagation of ISWs near the DSA.
Key Points
Spatial variations in ISW reconnections around the Dongsha Atoll were observed from SAR images
Numerical simulations of ISW refraction and reconnection were compared with SAR observations
Impacts of ocean stratification, background currents, and ISW characteristics on the reconnection behind the Dongsha Atoll were examined
Chronic hepatitis B (CHB) poses a serious threat to the health of the Chinese people. Viral markers are of great significance during antiviral therapy and research and development of innovative ...drugs. However, traditional serovirological markers such as HBV DNA and hepatitis B surface antigen (HBsAg) have certain limitations in assessing the efficacy of antiviral treatment and accurately reflecting the transcriptional activity of covalently closed circular DNA (cccDNA). In recent years, the role of new viral markers such as HBV RNA, hepatitis B core-related antigen (HBcrAg) and quantitative anti-hepatitis B core protein (qAnti-HBc) have attracted more and more attention because of accurately reflecting the transcription activity of cccDNA, determining the therapeutic effect and predicting the risk of recurrence after drug discontinuation. This article briefly introduces the application of new and old markers in various stages of antiviral therapy in CHB patients, and combines the application of new viral mark
Cutting signals can monitor the cutting status in metal cutting process such as acceleration, cutting force, motor current, and acoustic emission. In this paper, cutting force and spindle ...acceleration signals were analyzed and compared in milling titanium alloy thin-wall components and non-thin-wall components under the same cutting parameters. Tool wear was analyzed during the whole cutting process. Frequency spectrum and wavelet analysis methods were used in this study to illustrate the impact of tool wear on cutting force in milling two types of workpiece such as thin-wall and non-thin-wall components. The experimental results showed that cutting vibration in milling thin-wall components is obviously higher than in milling non-thin-wall components owing to its weak rigidity, which caused relatively small cutting force for the smaller cutting load. The cutting force frequency was decreased from the tooth passing frequency (TPF) to spindle frequency (SF) because each cutting edge withstands different cutting loads caused by the tool wear of each cutting edge. The energy contribution of TPF is biggest in early milling process, and the energy contribution of SF is well over that of FPF in the late milling process (when VB is greater than or equal to 0.18 mm) because serious tool wear caused each cutting edge to bear the different cutting loads.
We report constraints on the dark photon effective kinetic mixing parameter (κ) with data taken from two p-type point-contact germanium detectors of the CDEX-10 experiment at the China Jinping ...Underground Laboratory. The 90% confidence level upper limits on κ of solar dark photon from 205.4 kg-day exposure are derived, probing new parameter space with masses (m_{V}) from 10 to 300 eV/c^{2} in direct detection experiments. Considering dark photon as the cosmological dark matter, limits at 90% confidence level with m_{V} from 0.1 to 4.0 keV/c^{2} are set from 449.6 kg-day data, with a minimum of κ=1.3×10^{-15} at m_{V}=200 eV/c^{2}.
The influences of coal matrix expansion/contraction and effective stress on the permeability of coal with different thermal maturities are different during the CH4-CO2 replacement process due to ...different mechanical properties and gas adsorption capacities. To accurately predict the variation law of coal permeability during the CH4-CO2 replacement process, it is critical to understand how the matrix expansion/contraction and effective stress affect the permeability of coal at different thermal maturities during the CH4-CO2 replacement. In this study, the permeability of two coal specimens with anthracite and high-rank bituminous coal during the CH4-CO2 replacement process under different confining and injection pressures was tested using a CBM replacement testing machine. The results demonstrate that with decreasing gas injection pressure, the permeability of the two coal specimens exhibited a U-shaped correlation under different confining pressures. Under the same gas injection pressure, with increasing effective stress, the permeability presented a negative exponential decrease and the permeability of the anthracite decreased more significantly. Moreover, under the same confining pressure, with increasing gas injection pressure, the decreasing permeability agreed with Langmuir curve and the permeability of high-rank bituminous coal was more significantly reduced.
Purpose: This study aimed to characterize the pharmacokinetics of nalbuphine in patients undergoing general anesthesia with varying degrees of liver dysfunction. Patients and Methods: Twenty-four ...patients were enrolled and divided into three cohorts based on liver function: normal liver function (n = 13), mild liver dysfunction (n = 5), and moderate/severe liver dysfunction (n = 6). During the induction of anesthesia, they received 15 mg of nalbuphine intravenously. Venous blood samples were collected from each patient. The plasma concentration of nalbuphine was determined using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The pharmacokinetic parameters of nalbuphine were calculated by non-compartmental analysis (NCA) using Phoenix WinNonlin software. Results: Compared with the normal liver function group, the plasma elimination half-life (T1/2) of nalbuphine was increased by approximately 33% in the moderate/severe liver dysfunction group (2.66 h vs 3.54 h, P<0.05), and the volume of distribution (V.sub.d) increased by approximately 85% (100.08 L vs 184.95 L, P<0.05). Multivariate analysis revealed that weight and platelet were associated with clearance (CL); total bilirubin as an independent factor was associated with T1/2, and weight associated with area under the curve (AUC.sub.(0??infinity)) independently. Conclusion: The T.sub.1/2, mean residence time, and V.sub.d of nalbuphine in patients with moderate/severe liver dysfunction were prolonged or increased significantly compared with those in the normal liver function group. These data suggest that it may need to be used with caution when nalbuphine is administered to patients with moderate or severe liver dysfunction. Keywords: nalbuphine, intravenous, liver dysfunction, UPLC-MS/MS, pharmacokinetics
PDF
