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Quantum time-dependent wave-packet calculations have been carried out to explore the state-to-state dynamics of the ion–molecule (H−(D−),HD) collisions on two accurate ab initio potential energy surfaces in the collision energy range 0.2–1.2 eV. Total and final state-resolved integral and differential cross sections are elaborated in detail. The differential cross sections vary substantially with the collision energy, turning from predominantly backward-scattering at low collision energies to forward and sideways scattering bias at relatively high collision energies. The rebound, stripping and time-delayed mechanisms are found to be possible in (H−(D−),HD) collisions. A set of quasi-classical trajectory calculations were performed, and the results indicate that the backward-scattering peak is caused by the low impact parameter trajectories, while the trajectories of high impact parameter are responsible for the forward scattering. A set of representative state-to-state differential cross sections at collision energies 0.6 and 1.2 eV are also presented. Different reaction mechanisms are dominant in (H−(D−),HD) collisions at different collision energies, resulting in different product rovibrational state distributions. The differences between the dynamics results based on the two potential energy surfaces are also discussed. [ABSTRACT FROM AUTHOR]

Nitrous oxide (N2O) generation and emission from No. 3 wastewater treatment plant (WWTP) in Xi’an (Orbal oxidation ditch) and No. 4 WWTP in Xi’an (reversed A/A/O) were measured throughout a year following the water environment research foundation protocol. The N2O generation and emission rates of No. 4 WWTP (generation rate of 14.43 kg (N2O)/d and emission rate of 13.78 kg (N2O)/d) were about twice that of No. 3 WWTP (generation rate of 7.09 kg (N2O)/d and emission rate of 6.52 kg (N2O)/d). The N2O emission factor of No. 4 WWTP (54.64 mg (N2O)/m3INF) was about 1.7 times that of No. 3 WWTP (36.20 mg (N2O)/m3INF). The ammonia oxidation rate, nitrite oxidation rate, and nitrous oxide generation rate were also measured. Results showed that the key factors of N2O generation and emission were the microbial population and aeration strategy. [ABSTRACT FROM PUBLISHER]

Six low-lying states ( X 2 Σ g + , A 2 Π u , B 2 Σ u + , 4 Σ g + , 4 Π u and 4 Σ u + ) of C 2 − anion are studied by highly correlated ab initio calculations. The potential energy curves (PECs) are computed in the internuclear separation from 0.8 to 5.0 Å using the complete active space self-consistent field method, and then performing the internally contracted multireference configuration interaction with Davidson correction. Core–valence correlation and scalar relativistic effect are considered through employing the aug-cc-pcV5Z-dk basis set. The spin–orbit coupling of the A 2 Π u state is also calculated using Breit–Pauli Hamiltonian. Based on the PECs derived from the high-level ab initio calculations, the spectroscopic parameters are obtained by fitting the ro-vibrational levels that are acquired by solving the ro-vibrational Schrödinger equation. These spectroscopic parameters, especially for low-lying doublet states, are in good agreement with the previously calculated and experimental results. Finally, the electronic transition dipole moment matrix elements, Franck–Condon factors, radiative lifetimes and oscillator strengths of A 2 Π u – X 2 Σ g + and B 2 Σ u + - X 2 Σ g + are calculated and discussed as well. [ABSTRACT FROM AUTHOR]

A resolved line pair was selected for simultaneous measurement of carbon monoxide (CO) and carbon dioxide (CO2) in the near-infrared (NIR) region. The spectral lines of CO and CO2 at 1.578 µm were measured by wavelength modulation spectroscopy (WMS)-2f and the absorption was enhanced with a multipass absorption cell. The white noise was further reduced by averaging technology. The detection sensitivity (1σ) for the system is estimated at 2.63 × 10−7 cm−1 for direct absorption spectroscopy. The ultimate detection limits of CO2 and CO mixed with pure N2 at 75 Torr are 29 parts per million (ppm) and 47 ppm, respectively. It is demonstrated that the signal is highly linear with the concentration in the range of 100–800 ppm. Based on an Allan variation analysis, the minimum detectable limit of CO2 and CO is 7.5 and 14 ppm, respectively. The response time of the system is about 30 s and a relationship of temperature dependence was obtained. As an example, an in situ measurement of exhaust of alkane combustion emission is presented. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to develop and validate a prediction model for premature circuit clotting of continuous renal replacement therapy (CRRT) in critically ill patients., Design: A retrospective cohort study was conducted on ICU patients undergoing CRRT. The Medical Information Mart for Intensive Care-III Clinical Database CareVue subset and Medical Information Mart for Intensive Care-IV were utilized for model development, while the eICU Collaborative Research Database was employed for external validation. Predictive factors were selected through Least Absolute Shrinkage and Selection Operator Regression and univariate logistic regression. A prediction model was then developed using binary logistic regression. Internal and external validations assessed the model's discrimination, calibration, and clinical net benefit., Results: This study encompassed 2531 patients overall, with a premature circuit clotting rate of 31.88 %. The prediction model comprises five variables: body temperature, anticoagulation, mean arterial pressure, maximum transmembrane pressure change within two hours, and vasopressor. The model demonstrated robust predictive performance, achieving an area under the receiver operating characteristic curve of 0.897 (95 % CI: 0.879-0.915) in the training set and 0.877 (95 % CI: 0.852-0.902) in the external validation set. Internal validation yielded a Brier score of 0.087, while external validation showed a Brier score of 0.120. Calibration curves indicated good model calibration for both validations. The decision curve analysis indicates that the model yields a clinical net benefit across a wide range of decision thresholds., Conclusion: The model demonstrates robust discrimination, calibration, and clinical net benefit, with readily available variables indicating substantial potential for valuable clinical applications., Implications for Clinical Practice: Healthcare providers in the ICU can leverage the model to evaluate the risk of premature circuit clotting in critically ill patients undergoing continuous renal replacement therapy, facilitating timely intervention to mitigate its incidence., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

A laser-based spectrometer with a physical size of 60× 30 ×25 cm 3 has been developed to continuously monitor CO and CH 4 in atmosphere based on tunable diode laser absorption spectroscopy (TDLAS). Two neighboring lines of CO and CH 4 around 2.3 μm were selected as candidates for simultaneous measurement by a single diode distributed feedback (DFB) laser. A special Herriott-type multipass absorption cell, with a 72 m optical path length, was designed and used to enhance the absorption signals of sample gases. Normalized wavelength modulation spectroscopy was applied to improve the sensitivity and robustness of the spectrometer and it was implemented on a home-made electronic system based on field programmable gate array (FPGA). Meanwhile, the electronic system controlled the temperature and current of DFB laser with the precision of 0.01 °C and 40 ppm. The 2nd-harmonic signals normalized by the corresponding 1st-harmonic signals for both CO and CH 4 are of high linear response to their concentrations in the range of 0.046-4.6 ppm and 0.487-48.7 ppm, respectively. According to the Allan variance, respective minimum detection limits for CO and CH 4 are 0.73 ppb and 36 ppb at 122 s and 137 s. As an application example, the spectrometer has been validated through real-time and in-situ measurement of atmospheric CO and CH 4 for 48 h., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Quantum time-dependent wave-packet calculations have been carried out to explore the state-to-state dynamics of the ion-molecule (H-(D-),HD) collisions on two accurate ab initio potential energy surfaces in the collision energy range 0.2-1.2 eV. Total and final state-resolved integral and differential cross sections are elaborated in detail. The differential cross sections vary substantially with the collision energy, turning from predominantly backward-scattering at low collision energies to forward and sideways scattering bias at relatively high collision energies. The rebound, stripping and time-delayed mechanisms are found to be possible in (H-(D-),HD) collisions. A set of quasi-classical trajectory calculations were performed, and the results indicate that the backward-scattering peak is caused by the low impact parameter trajectories, while the trajectories of high impact parameter are responsible for the forward scattering. A set of representative state-to-state differential cross sections at collision energies 0.6 and 1.2 eV are also presented. Different reaction mechanisms are dominant in (H-(D-),HD) collisions at different collision energies, resulting in different product rovibrational state distributions. The differences between the dynamics results based on the two potential energy surfaces are also discussed.

A resolved line pair was selected for simultaneous measurement of carbon monoxide (CO) and carbon dioxide (CO 2 ) in the near-infrared (NIR) region. The spectral lines of CO and CO 2 at 1.578 µm were measured by wavelength modulation spectroscopy (WMS)-2 f and the absorption was enhanced with a multipass absorption cell. The white noise was further reduced by averaging technology. The detection sensitivity (1σ) for the system is estimated at 2.63 × 10 -7  cm -1 for direct absorption spectroscopy. The ultimate detection limits of CO 2 and CO mixed with pure N 2 at 75 Torr are 29 parts per million (ppm) and 47 ppm, respectively. It is demonstrated that the signal is highly linear with the concentration in the range of 100-800 ppm. Based on an Allan variation analysis, the minimum detectable limit of CO 2 and CO is 7.5 and 14 ppm, respectively. The response time of the system is about 30 s and a relationship of temperature dependence was obtained. As an example, an in situ measurement of exhaust of alkane combustion emission is presented.