Advances and Challenges in Speciation Measurement and Microkinetic Modeling for Gas-Solid Heterogeneous Catalysis.

Microkinetic modeling of heterogeneous catalysis serves as an efficient tool bridging atom-scale first-principles calculations and macroscale industrial reactor simulations. Fundamental understanding of the microkinetic mechanism relies on a combination of experimental and theoretical studies. This Perspective presents an overview of the latest progress of experimental and microkinetic modeling approaches applied to gas-solid catalytic kinetics.

A compact and fast radio-frequency source for efficient Raman sideband cooling.

A compact and fast radio-frequency (RF) source developed for Raman sideband cooling (RSBC) in trapped ion and cold atom experiments is presented. The source is based on direct digital synthesizer, advanced real-time infrastructure for quantum physics, and field programmable gate array. The source has a frequency switching speed of 40 ns and can output continuous μs-level time sequences for RSBC.

Investigating the Kinetics of Heterogeneous Lipid Ozonolysis by an Online Photoionization High-Resolution Mass Spectrometry Technique.

Lipid oxidation-induced imbalance in the redox system is one of the key causative factors leading to accelerated aging in living organisms and related diseases. Online sampling and analysis of the heterogeneous ozonolysis kinetics of lipid aerosols are highly important in revealing the oxidation-driven aging process of lipids. In this paper, an online detection method based on atmospheric pressure photoionization combined with ultrahigh resolution mass spectrometry (APPI-HRMS) is developed for real-time analysis of the heterogeneous reactions between lipid particles (oleic acid and squalene) and ozone.

High performance molecular iodine optical reference using an unsaturated vapor cell.

We describe a high-performance molecular iodine optical frequency reference that is referenced to the R(56)32-0: a1 hyperfine transition of molecular iodine based on modulation transfer spectroscopy. We design an unsaturated iodine vapor cell with a gas pressure equivalent to the saturation pressure at -17 °C. Using this cell, we developed a compact, frequency-stabilized laser.

Noise characterization of an ultra-stable laser for optical clocks.

We report on the development and performance evaluation of an ultra-stable laser for an 27Al+ optical clock. After a series of noise suppressions, especially the vibrational and temperature fluctuation noise, the 30 cm long cavity stabilized laser obtains a frequency instability of 1.3 × 10-16 @1 s.

Electrochemical Generation of Te Vacancy Pairs in PtTe for Efficient Hydrogen Evolution.

Two-dimensional (2D) van der Waals materials are increasingly seen as potential catalysts due to their unique structures and unmatched properties. However, achieving precise synthesis of these remarkable materials and regulating their atomic and electronic structures at the most fundamental level to enhance their catalytic performance remain a significant challenge. In this study, we synthesized single-crystal bulk PtTe crystals via chemical vapor transport and subsequently produced atomically thin, large PtTe nanosheets (NSs) through electrochemical cathode intercalation.

Development of Taste Sensor with Lipid/Polymer Membranes for Detection of Umami Substances Using Surface Modification.

A taste sensor employs various lipid/polymer membranes with specific physicochemical properties for taste classification and evaluation. However, phosphoric acid di(2-ethylhexyl) ester (PAEE), employed as one of the lipids for the taste sensors, exhibits insufficient selectivity for umami substances. The pH of sample solutions impacts the dissociation of lipids to influence the membrane potential, and the response to astringent substances makes accurate measurement of umami taste difficult.

Multi-channel EEG-based sleep staging using brain functional connectivity and domain adaptation.

Sleep stage recognition has essential clinical value for evaluating human physical/mental condition and diagnosing sleep-related diseases. To conduct a five-class (wake, N1, N2, N3 and rapid eye movement) sleep staging task, twenty subjects with recorded six-channel electroencephalography (EEG) signals from the ISRUC-SLEEP dataset is used.Unlike the exist methods ignoring the channel coupling relationship and non-stationarity characteristics, we developed a brain functional connectivity method to provide a new insight for multi-channel analysis.

Quantitative risk assessment of China's first liquid hydrogen refueling station.

Hydrogen refueling stations (HRSs) are among the most important infrastructures for fuel cell vehicles. However, the safety issue of HRSs has become a key constraint to the wide application and development of hydrogen energy. This article presents a quantitative risk assessment of the first liquid HRS (LHRS) in China and conducts a comprehensive assessment in terms of both individual (IR) and societal risks (SRs).

DBF-Net: a semi-supervised dual-task balanced fusion network for segmenting infected regions from lung CT images.

Accurate segmentation of infected regions in lung computed tomography (CT) images is essential to improve the timeliness and effectiveness of treatment for coronavirus disease 2019 (COVID-19). However, the main difficulties in developing of lung lesion segmentation in COVID-19 are still the fuzzy boundary of the lung-infected region, the low contrast between the infected region and the normal trend region, and the difficulty in obtaining labeled data. To this end, we propose a novel dual-task consistent network framework that uses multiple inputs to continuously learn and extract lung infection region features, which is used to generate reliable label images (pseudo-labels) and expand the dataset.

Dual-frequency fundamental-mode NPRO laser for low-noise microwave generation.

Monolithic nonplanar ring oscillators (NPROs) have achieved great success in industry, scientific applications and space missions due to their excellent narrow-linewidth, low-noise, high beam-quality, lightweight and compact performances. Here, we show that stable dual-frequency or multi-frequency fundamental-mode (DFFM or MFFM) laser can be stimulated directly by tunning pump divergence-angle and beam-waist injected to NPRO. The DFFM laser has a frequency deviation of one free spectral range of the resonator and thus can be utilized for pure microwave generation by common-mode-rejection.

AP-HTPB propellant combustion under strain conditions with laser absorption spectroscopy.

Understanding the combustion behaviors of solid propellant with different levels of strains is of practical interest. In this work, an experimental study of the effects of static and dynamic strains on the burning rate, temperature, CO, and formation of aluminized ammonium perchlorate (AP)-hydroxyl terminated poly-butadiene (HTPB) propellant combustion was presented at initial pressures of 0.1 MPa, 0.

PDRF-Net: a progressive dense residual fusion network for COVID-19 lung CT image segmentation.

The lungs of patients with COVID-19 exhibit distinctive lesion features in chest CT images. Fast and accurate segmentation of lesion sites from CT images of patients' lungs is significant for the diagnosis and monitoring of COVID-19 patients. To this end, we propose a progressive dense residual fusion network named PDRF-Net for COVID-19 lung CT segmentation.

FCKDNet: A Feature Condensation Knowledge Distillation Network for Semantic Segmentation.

As a popular research subject in the field of computer vision, knowledge distillation (KD) is widely used in semantic segmentation (SS). However, based on the learning paradigm of the teacher-student model, the poor quality of teacher network feature knowledge still hinders the development of KD technology. In this paper, we investigate the output features of the teacher-student network and propose a feature condensation-based KD network (FCKDNet), which reduces pseudo-knowledge transfer in the teacher-student network.

A Mechanistic Study of HZSM-5-Catalyzed Guaiacol Amination Using Photoionization Time-of-Flight Mass Spectrometry.

Thermal-catalytic conversion and amination (TCC-A) of lignin and lignin derivates over zeolites is a promising and renewable method to produce aromatic amines, but suffers from product diversity. Currently, no unambiguous mechanism could fully describe the chemistry of this process. In this work, the TCC-A mechanism of guaiacol, a typical lignin model compound, with ammonia over HZSM-5 was investigated by online photoionization time-of-flight mass spectrometry combined with density functional theory.

Probing combustion and catalysis intermediates by synchrotron vacuum ultraviolet photoionization molecular-beam mass spectrometry: recent progress and future opportunities.

Soft photoionization molecular-beam mass spectrometry (PI-MBMS) using synchrotron vacuum ultraviolet (SVUV) light has been significantly developed and applied in various fields in recent decades. Particularly, the tunability of SVUV light enables two-dimensional measurements, mass spectrum and photoionization efficiency spectrum measurements, affording isomer distinguishment in complex reaction processes. Many key intermediates have been successfully detected in combustion and catalysis reactions with the help of the state-of-the-art SVUV-PI-MBMS, promoting the understanding of the chemical mechanisms.

Short-term developmental outcomes in neonates born to mothers with COVID-19 from Wuhan, China.

Background: Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an emerging disease. The consequences of SARS-CoV-2 exposure in infants remain unknown. Therefore, this study aims to investigate whether neonates born to mothers with COVID-19 have adverse brain development.

Insights into the Decomposition and Oxidation Chemistry of -Xylene in Laminar Premixed Flames.

This work reports an experimental and kinetic modeling investigation on laminar premixed flame of -xylene at 0.04 atm and equivalence ratios of 0.75, 1.

Effects of SARS-CoV-2 infection on neuroimaging and neurobehavior in neonates.

Background: We collected neonatal neurological, clinical, and imaging data to study the neurological manifestations and imaging characteristics of neonates with coronavirus disease 2019 (COVID-19).

Methods: This case-control study included newborns diagnosed with COVID-19 in Wuhan, China from January 2020 to July 2020. All included newborns had complete neurological evaluations and head magnetic resonance imaging.

Silencing of Long Non-Coding RNA X Inactive Specific Transcript (Xist) Contributes to Suppression of Bronchopulmonary Dysplasia Induced by Hyperoxia in Newborn Mice via microRNA-101-3p and the transforming growth factor-beta 1 (TGF-β1)/Smad3 Axis.

BACKGROUND Bronchopulmonary dysplasia (BPD) is a chronic lung disease mostly affecting premature infants. Long non-coding RNA (lncRNA) X inactive specific transcript (Xist) is actively involved in pulmonary disease development. The present study explored the potential mechanism of Xist in BPD development.

Neonatal Early-Onset Infection With SARS-CoV-2 in 33 Neonates Born to Mothers With COVID-19 in Wuhan, China.

This cohort study examines medical records of 33 neonates born to women with COVID-19 to provide information on maternal-child transmission and infant outcomes.

Experimental and kinetic modeling investigation of rich premixed toluene flames doped with n-butanol.

n-Butanol is a promising renewable biofuel and has a lot of advantages as a gasoline additive compared with ethanol. Though the combustion of pure n-butanol has been extensively investigated, the chemical structures of large hydrocarbons doped with n-butanol, especially for aromatic fuels, are still insufficiently understood. In this work, rich premixed toluene/n-butanol/oxygen/argon flames were investigated at 30 Torr with synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS).

[Value of arterial blood lactic acid in the evaluation of disease severity and prognosis in neonatal shock].

Objective: To evaluate the value of blood lactic acid (BLA) as a predictor for the severity and prognosis of neonatal shock.

Methods: A total of 326 neonates with shock were enrolled and divided into three groups based on the severity, namely mild group (n=147), moderate group (n=105), and severe group (n=74). BLA level was measured during and early after (about 6 hours later) fluid resuscitation, and lactate clearance rate (LCR) was calculated.

[Change of Thrombelastography in Children's DIC and Analysis of Its Sensitivity and Specificity for Diagnosis of DIC].

Objective: To investigate the influence of thrombelastography index changes on its sensitivity and specificity for diagnosis of disseminated intravascular coagulation (DIC) in children.

Methods: A total of 149 children with DIC in our hospital from June 2013 to June 2016 were selected in DIC group, while 106 cases of non-DIC, including healthy children and children with diseases easily confused with DIC, were selected as non-DIC(control) group. The thrombelastography, D-dimer, coagulation functions including prothrombintime (PT), activated partial thromboplastin time (APTT), fibrinogen (FIB) and fibin degradation product (FDP), congental coagulation disorders and platelet count were detected in DIC and non-DIC groups; the statistics of data was performed and the sensitivity and specificity of thromelastraphy indexes such as R time, α angle MA value and A value were evaluated; the relationship of DIC with indexes was analyzed.

[Temporal and spatial variations of the nitrate-nitrogen sources in an underground river using 15N isotope technique].

Groundwater in Qingmuguan underground river was monitored using hydro-chemical and 15N isotope techniques to investigate temporal and spatial variations of nitrate-nitrogen and its possible sources from October, 2007 to October, 2008. The results show that nitrate concentrations are 3.20 mg/L of the inlet (D1) and 20.