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The self-noise level of a seismometer can determine the performance of the seismic instrument and limit the ability to use seismic data to solve geoscience problems. Accurately measuring and simultaneously comparing the self-noise models from different types of seismometers has long been a challenging task due to the constraints of observation conditions. In this paper, the self-noise power spectral density (PSD) values of nine types of seismometers are calculated using four months of continuous seismic waveforms from Malingshan seismic station, China, and nine self-noise models are obtained based on the probability density function (PDF) representation. For the seismometer STS-2.5, the self-noise levels on the horizontal channels (E–W and N–S) are significantly higher than that on the vertical channel (U–D) in the microseism band (0.1 Hz to 1 Hz), which is a computing bias caused by the misalignment between the sensors in the horizontal direction, while the remarkably elevated noise on the horizontal channels at the low frequencies (<0.6 Hz) may originate from the local variation of atmospheric pressure. As for the very broadband seismometers Trillium-Horizon-120 and Trillium-120PA, and the ultra-broadband seismometers Trillium-Horizon-360 and CMG-3T-360, there is a trade-off between the microseism band range and low-frequency range in the PSD curves of the vertical channel. When the level of self-noise in the microseism band is high, the self-noise at low frequencies is relatively low. Although compared with the other very broadband seismometers, the self-noise level of the vertical component of the STS-2.5 is 3 dB to 4 dB lower at frequencies less than 1 Hz, the self-noise level of the STS-2.5 at high frequencies (>2 Hz) is slightly higher than others. From our observations, we conclude that the nine seismometers cannot reach the lowest noise level in all frequency bands within the working range. [ABSTRACT FROM AUTHOR]

Direct electrocatalytic oxidation of benzene has been regarded as a promising approach for achieving high‐value phenol product, but remaining a huge challenge. Here an oxygen‐coordinated nickel single‐atom catalyst (Ni–O–C) is reported with bifunctional electrocatalytic activities toward the two‐electron oxygen reduction reaction (2e− ORR) to H2O2 and H2O2‐assisted benzene oxidation to phenol. The Ni–(O–C2)4 sites in Ni–O–C ar proven to be the catalytic active centers for bifunctional 2e− ORR and H2O2‐assisted benzene oxidation processes. As a result, Ni–O–C can afford a benzene conversion as high as 96.4 ± 3.6% with a phenol selectivity of 100% and a Faradaic efficiency (FE) of 80.2 ± 3.2% with the help of H2O2 in 0.1 m KOH electrolyte at 1.5 V (vs RHE). A proof of concept experiment with Ni–O–C concurrently as cathode and anode in a single electrochemical cell demonstrates a benzene conversion of 33.4 ± 2.2% with a phenol selectivity of 100% and a FE of 44.8 ± 3.0% at 10 mA cm−2. [ABSTRACT FROM AUTHOR]

The in-situ measurements for r-tables have attracted special attention owing to their advantages, including increased speed, simplicity of use, and nondestructive road effects. This study presents a database retrieval method proposed for the construction of a full-scale r-table from an r-table database with 25 r coefficients used as input parameters. The proposed method was used in an in-situ, r-table measurement device as a data processing algorithm. To evaluate the accuracy of the proposed method, we performed a) a table-to-table comparison of Q0, S1, and r-tables constructed by different methods and b) comparisons of calculated luminance values (Lave, U0, Ul) for a typical road-lighting scenario based on the use of different r-tables. The table-to-table comparison results indicate that following the application of the proposed method, its calculated Q0, S1, and r-table values were very close to their actual values (EQ0 = 2.1%, ES1 = 5.0%, Error = 2.3%). Moreover, the proposed method also exhibits an improved luminance response and achieves a 2.1% difference in Lave, a 3% difference in U0, and a 1.8% difference in Ul. This study proves that the proposed database retrieval method improves the model prediction accuracy. [ABSTRACT FROM AUTHOR]

Electrochemical N2 reduction reaction (NRR) provides an alternative approach to producing ammonia (NH3) under ambient conditions. However, the sluggish kinetic process and existence of the competitive reaction of hydrogen evolution reaction make the catalytic activity and selectivity of NRR catalysts still very low. To tackle this challenge, gold-modified molybdenum carbide (Mo2C) nanoparticles (NPs) supported on nitrogen-doped carbon nanotubes (Au/Mo2C/NCNTs) was synthesized using a strategy that combines laser irradiation and carbothermal reaction. For such a composite, pony-sized Mo2C nanocrystals play important roles in cleavage of the NN bond and the occurrence of N2 adsorption, while Au NPs promote charge transfer and intermediate protonation to enhance the selectivity of NRR. Using these advantages, the NH3 yield rate and Faradaic efficiency of Au/Mo2C/NCNTs reached 46.89 μg mgcat.–1 h–1 and 2.78% at −0.3 V versus reversible hydrogen electrode, which were 2.36 and 3.20 times those of Mo2C/NCNTs, respectively. Our effort provides a unique pathway for preparing Au/Mo2C/NCNTs composites and gives insight into the mechanism of the NRR performance enhanced by metal NP loading and heteroatom doping. [ABSTRACT FROM AUTHOR]

Background: The purpose of this retrospective study was to investigate the determinants of postoperative respiratory failure in elderly patients with hip fracture. Methods: The subjects of this study were 663 elderly patients who had hip fracture and had been treated with hip surgery at our hospital from January 2014 to May 2020. According to the occurrence of postoperative respiratory failure, 626 patients with no respiratory failure were retrospectively included in the control group, and 37 cases combined with respiratory failure were enrolled in the PRF group. The clinical and surgical data of the two groups were collected and analyzed to evaluate the determinants of respiratory failure by logistic regression analysis. Results: There were no significant differences in the demographics and baseline variables including age, gender, fracture type and location between the groups (P > 0.05). All patients received hip surgery including total hip arthroplasty (THA), hemiarthroplasty (HA) and internal fixation with PFNA (proximal femoral nail anti-rotation). There were no significant differences in operative time and intraoperative blood loss between the groups (P > 0.05). However, close associations were found between pulmonary hypertension (univariate analysis: OR = 3.792, 95% CI = 1.421–10.203; multivariate analysis: OR = 1.132, 95% CI = 1.003–1.251), obstructive pulmonary disease (OR = 1.119, 95% CI = 1.009–1.238; multivariate analysis: OR = 13.298, 95% CI = 4.021–43.298), bronchiectasis and emphysema (OR = 4.949, 95% CI = 1.919–9.873; multivariate analysis: OR = 11.231, 95% CI = 187.87), and history of respiratory failure (OR = 6.098, 95% CI = 2.012–12.198; multivariate analysis: OR = 8.389, 95% CI = 2.391–21.982) with postoperative respiratory failure (P < 0.05). Conclusion: Pulmonary hypertension, obstructive pulmonary disease, bronchiectasis, emphysema, history of respiratory failure, and hypoproteinemia may be risk factors for postoperative respiratory failure in elderly patients with hip fracture. [ABSTRACT FROM AUTHOR]