University Of Science And Technology Of China Research Articles

Comparison of the imaginary parts of the atmospheric refractive index structure parameter and aerosol flux based on different measurement methods

Abstract. The complexity of aerosol particle properties and the diversity of characterizations make aerosol vertical transport flux measurements and analysis difficult. Although there are different methods, such as aerosol particle number concentration flux and aerosol mass flux based on the eddy covariance principle as well as aerosol mass flux measurements based on the light-propagated large-aperture scintillation principle, there is a lack of mutual validation among the different methods. In this paper, a comparison of aerosol mass flux measurements based on the eddy covariance principle and aerosol mass flux measurements based on the light-propagated large-aperture scintillation principle is carried out. The key idea of aerosol mass flux measurements based on the light-propagated large-aperture scintillation principle is the determination of the imaginary part of the atmospheric equivalent refractive index structure parameter (AERISP). In this paper, we first compare the AERISPs measured by two different methods and then compare the aerosol mass vertical transport fluxes obtained by different methods. The experiments were conducted on the campus of the University of Science and Technology of China (USTC). A light propagation experiment was carried out between two tall buildings to obtain the imaginary and real parts of the AERISPs for the whole path, which in turn can be used to obtain the aerosol vertical transport flux. An updated visibility meter is installed on the meteorological tower in the middle of the light path, which is utilized to obtain the single-point visibility, which is then converted to the imaginary part of the atmospheric equivalent refractive index (AERI). The imaginary parts of the AERISP were obtained via spectral analysis with visibility data. The results show that the imaginary parts of the AERISPs obtained by different methods are in good agreement. The imaginary part of the AERI measured by the visibility meter and the vertical wind speed obtained by the ultrasonic anemometer were used for covariance calculations to obtain the aerosol vertical transport flux. The trends in aerosol vertical transport fluxes obtained by the different methods are consistent, and there are differences in some details, which may be caused by the inhomogeneity in the vertical transport of aerosol fluxes. The experimental results also showed that urban green land is a sink area for aerosol particles.

Development of μSR apparatuses for a pulsed muon source at China Spallation Neutron Source

Muon spin rotation/relaxation/resonance (μSR) spectroscopy uses highly polarized muons to study the microscopic magnetic structure and dynamics of condensed matter. In addition to the five existing muon facilities, the first Chinese muon source, the Muon station for sciEnce technoLOgy and inDustrY (MELODY), is planned to be constructed in Phase II of the China Spallation Neutron Source (CSNS). It aims to provide intense and pulsed muon beams to conduct μSR applications in multiple disciplines. The group from the University of Science and Technology of China (USTC) participated in the collaboration with the CSNS accelerator group for the construction of the muon source. The USTC group led the research and development (R&D) of the first-generation photomultiplier tube (PMT)-based μSR spectrometer, and the design of the second-generation silicon photomultiplier (SiPM)-based spectrometer. The PMT-based spectrometer is a 128-channel prototype to demonstrate and develop key detector and electronics technologies for the planned MELODY. After several iterative designs and updates of detectors and electronics, the spectrometer prototype achieved a 7-ns dead time, which can record more than 12 positrons per channel per pulse according to the ISIS running experience. Based on the technologies developed from the first-generation spectrometer, the second-generation spectrometer will use SiPMs to accommodate over 2500 detector units to make better use of muons in MELODY. The two generation developments of Chinese μSR spectrometers will greatly advance the construction of MELODY, and provide high-quality data for users to interpret material properties in the near future.

Detectability of Fast Radio Burst Optical Counterparts with the Future Chinese Wide Field Telescopes

Fast Radio Bursts (FRBs) are extra-galactic origin milli-second duration bright radio bursts. Theoretically, FRBs may produce optical counterparts with durations from milliseconds to hours. The FRB optical counterparts may be detectable in future large field telescopes, including the China Space Station Telescope (CSST), the 2.5-meter Wide Field Survey Telescope (WFST) lead by the University of Science and Technology of China (USTC) and the Purple Mountain Observatory (PMO), and the Earth 2.0 (ET). The fast radio burst optical counterparts are grouped into millisecond time-scale optical counterparts, hourly time-scale optical counterparts, and optical afterglow for our study. The first two can be generated by the high-energy extension of the radio radiation of fast radio bursts and the inverse Compton scattering of high-energy electrons. The event rates highly depend on the optical-to-radio flux ratio ην. For millisecond duration optical counterparts, the detection rate of WFST, CSST, and ET can reach hundreds per year in an ideal case. If ην∼10−3, the corresponding annual detection rates of WFST and CSST are in the order of 1, and the annual detection rate of ET is 19.5. For the hourly timescale optical counterparts, ideally, the age of the supernova remnant is 5 years, ην is about 10−6, and the annual detection rates are above 100. The X-ray counterpart of FRB 200428 indicates that FRBs may produce relativistic outflow, which will interact with the interstellar medium to produce optical afterglows. Combined with the standard afterglow model, the detectability of optical afterglow is explored with a simulation of fast radio bursts following the redshift and energy distribution from the literature. With a total energy-radio energy ratio similar to FRB 200428, (ζ=105), the estimated annual detection rates of CSST, WFST, and ET are 1.3, 1.0, and 67, respectively.

Clinical characteristics and risk factors for late-onset pneumocystis jirovecii pneumonia in kidney transplantation recipients.

Pneumocystis jirovecii pneumonia (PJP) is a common and troublesome complication of kidney transplantation. In the era of prophylaxis, the peak incidence of PJP after kidney transplantation and specific characteristics of late-onset PJP have always been debated. We performed a retrospective study by analysing the data of post-transplantation pneumonia in adult kidney transplantation recipients between March 2014 and December 2021 in The Affiliated First Hospital of University of Science and Technology of China (USTC). A total of 361 patients were included and divided into early-onset PJP, late-onset PJP and non-PJP groups. The characteristics of each group and related risk factors for the late-onset patients were investigated. Some patients developed PJP 9 months later with a second higher occurrence between month 10 and 15 after transplantation. Compared with non-PJP, ABO-incompatible and cytomegalovirus (CMV) viremia were significantly associated with late onset of PJP in multivariate analysis. The use of tacrolimus, CMV viremia, elevated CD8(+) T cell percent and hypoalbuminemia were risk factors for late PJP. Receiver operating characteristic curve analysis demonstrated that a combination of those factors could increase the sensitivity of prediction remarkably, with an area under the curve of 0.82, a sensitivity of 80% and a specificity of 83%. PJP could occur months after kidney transplantation. ABO-incompatible transplant recipients are at high risk of PJP. In the later stages of transplantation, CMV viremia, T lymphocyte subsets percentage and serum albumin levels should be monitored in patients using tacrolimus.

Effects of dexmedetomidine dosage on the short-term cognitive function of elderly patients undergoing cardiac surgery

BackgroundThis study aimed to investigate the effects of perioperative dexmedetomidine (DEX) infusion rates on the postoperative short-term cognitive function.MethodsA total of 88 patients aged ≥ 60 years who underwent cardiac surgery from January 2022 to November 2022 at the First Affiliated Hospital of The University of Science and Technology of China (USTC) were included. Based on a single-center pilot analysis, patients were divided into two groups according to the rate of intraoperative DEX infusion, which started after tracheal intubation and continued until 1 h before extubation in the cardiac surgery intensive care unit. In Group L (n = 44), the infusion rate was 0.1–0.5 µg/kg/h (low-dose group), whereas in Group H (n = 44), the infusion rate was 0.5–0.9 µg/kg/h (high-dose group). Clinical outcomes were then compared between the groups. The Mini–Mental State Evaluation (abbreviated as MMSE1, MMSE2, MMSE3, and MMSE4) scale was used for the assessment of cognitive function, which was conducted on postoperative Days 2 (T1), 7 (T2), 14 (T3), and 28 (T4), with the score from postoperative Day 2 (MMSE1) considered as the primary observation.ResultsPatients in Group L had higher MMSE1 scores compared to those in Group H (26.0 [24.0, 27.0] vs. 24.5 [22.0, 26.0], p = 0.046), and there was no significant difference in the scores between the groups at all subsequent time points. Group H exhibited a higher incidence of hypotension and bradycardia compared to Group L (p = 0.044 and p = 0.047, respectively).ConclusionsCompared to a high dose (0.5–0.9 µg/kg/h) of DEX infusion, a low-dose (0.1–0.5 µg/kg/h) infusion started after induction of anesthesia and continued until 1 h before extubation improved postoperative cognitive function scores on postoperative Day 2 in patients aged 60 years and older.Trial registrationURL: www.chictr.org.cn with registration number ChiCTR2100055093, registered on 31/12/2021.

Chinese Neonatal Nurses' Lived Experiences of Providing End-of-Life Care in the NICU: A Descriptive Phenomenological Study.

Although end-of-life care (EOLC) has been well-studied, the experience of neonatal intensive care unit (NICU) nurses in China, where little EOLC training is provided, requires further investigation. To explore the lived experience of EOLC delivery among NICU nurses, to provide evidence to enhance nurses' EOLC skills and improve their overall quality. This qualitative study adopted a phenomenological approach. A total of 11 NICU nurses participated in semistructured in-depth interviews between June and July 2022 at the First Affiliated Hospital of University of Science and Technology of China (USTC). Colaizzi's 7-step method was used to analyze the data. Five main themes were identified: (a) multiple emotions are experienced during EOLC delivery; (b) EOLC delivery is stressful from various sources for nurses; (c) expressing empathy and compassion is important; (d) ethical and clinical decision-making are key components of EOLC delivery; and (e) there are challenges in improving neonatal EOLC understanding and delivery. The experience of EOLC among Chinese NICU nurses is multidimensional and intensive. Institutions or units must establish and implement related protocols and guidelines to address differences between clinical practice and ideal protocols for neonatal EOLC. Educational programs that consider nurses' personal and interpersonal factors, including local culture, must be developed. Neonatal nurses in Western countries encountering Chinese-born parents who have lost their infants can gain an understanding of parents' perceptions from this study. Future research should focus on developing and testing interventions to train and support NICU nurses working with end-of-life neonates.

SUMMER：A small modular lead-bismuth-cooled fast reactor for mobile energy supply

The pursuit of small modular reactors (SMRs) has become a trend in this century due to their potential to expand the use of clean and reliable nuclear energy to a broader range of customers and applications. One promising candidate is the lead-based fast reactor. A mobile energy supply unit based on a lead-bismuth-cooled, pool-type, small modular fast reactor named SUstainable Modular Mobile Enhanced Reactor (SUMMER) is being developed by the University of Science and Technology of China (USTC) and China Nuclear Power Technology Research Institute. SUMMER is intended to provide stable energy supply in the field or remote regions, which are potential application scenarios for SMRs. Key features of SUMMER include a long lifetime of over a decade, mobility (transportable by truck or train), and inherent safety. In this paper, the reactor design is completed under the constraints of fulfilling these features, such as the limitation of size and lifetime. Neutronic and thermal-hydraulic analyses are implemented, as well as safety analyses of the reactor under several typical accidents. The results show that the design meets all these criteria and that the reactor has an adequate safety margin under both steady-state and transient conditions.

Dynamic Surface Antifouling Materials

Comprehensive SummaryThe colonization of marine microorganisms, animals and plants on underwater surface forms marine biofouling. It has profound effects on marine industries. To solve the problem, we proposed a strategy of Dynamic Surface Antifouling (DSAF), i.e., continuously changing surfaces can effectively inhibit biofouling organisms landing and adhering, and developed degradable polymer based marine antifouling material. The degradation of polymer chain enables the surface dynamic or self‐renewing even on static conditions. The final degradation products of these polymers are low molecular weight molecules, and do not produce marine microplastics. Meanwhile, the degradable polymers act as carriers and controlled release systems for antifoulants, further improving the antifouling efficiency. This article reviews the development of dynamic surface antifouling materials.What is the most favorite and original chemistry developed in your research group?Synthesis of marine anti‐biofouling polymers.How do you get into this specific field? Could you please share some experiences with our readers?I happened to read a paper about marine biofouling on the internet three months later after I joined University of Science and Technology of China (USTC). Its adverse effects on marine industry and marine activities shocked me very much! No doubt, it makes great significance for our country and society to solve the problem. It is a challenge, but I like challenge, and I decided to get into this field. Realizing that the key is to develop new polymer resin, I was confident that I was able to solve the problem with my polymer chemistry and physics background. Actually, it is not easy. I have spent about 20 years in this project since then.What is the most important personality for scientific research?Curiosity, interest, concentration and persistence. How do you keep balance between research and family?I make a plan and organization for everything so I can keep a balance between family and work.Who influences you mostly in your life?Prof. Ming Jiang and Prof. Chi Wu, who are my PhD and post‐doctor supervisors, respectively. They taught me how to do research and how to choose a significant subject.What is your favorite journal(s)?Macromolecules, Journal of the American Chemical Society, Physical Review Letters.Could you please give us some advices on improving Chinese Journal of Chemistry?The journal may publish more papers about applications of chemistry and history of chemistry.

Consideration of the Clinical Diagnosis of Allergic Fungal Sinusitis: A Single-Center Retrospective Study.

Allergic fungal rhinosinusitis (AFRS) is characterized by refractory and high recurrence rate. Improper treatment may lead to repeated recurrence and even serious complications, including vision loss, blindness, and intracranial complications. However, AFRS is easy to be misdiagnosed clinically. To ensure early diagnosis, the clinical presentations of patients with AFRS were studied. Data from patients with sinusitis hospitalized in the First Affiliated Hospital of the University of Science and Technology of China (USTC) from January 2015 to October 2022 were collected. The patients were divided into three groups; group A patients with AFRS, group B patients suspected of AFRS, and group C patients with fungus ball sinusitis (FBS).We retrospectively analyzed the data using IBM SPSS 19.0 to perform the chi-square test and one-way ANOVA test. In total, 35 cases of AFRS, 91 cases of suspected AFRS, and 661 cases of FBS were rediagnosed. Compared with FBS patients, AFRS patients were younger, the total IgE, the percentage of eosinophils and basophils in peripheral blood were higher, and the proportion of patients with allergic rhinitis, asthma or hypo olfactory was higher. It had a higher recurrence rate. These results were also observed in the comparison between suspected AFRS patients and FBS patients, but no significant difference was found in the comparison between suspected AFRS patients and suspected AFRS patients. AFRS may be misdiagnosed due to the low detection of fungi. To ensure early diagnosis, we recommend that patients with clinical, radiological, and laboratory features similar to those of AFRS but without evidence of fungal staining be treated according to the treatment criteria of AFRS.

Conceptual design of oil field energy supply system based on natural circulation lead–bismuth fast reactor

To meet the specific requirements of heavy oil thermal recovery and realize clean and efficient recovery, University of Science and Technology of China (USTC) and China Nuclear Power Technology Research Institute Co., Ltd. jointly designed NCLFR-Oil, an oil field energy supply system based on natural circulation lead–bismuth fast reactor. The system uses a small modular reactor with a thermal power of 40 MWth, which is compact and has a lifetime of more than 15 years. In this paper, the overall design, core neutron characteristics and steady-state thermal–hydraulic design of the reactor are described and evaluated. And the steady-state thermal–hydraulic characteristics of the reactor core as well as the whole three loops are analyzed and discussed. The results show that the reactor meets the safety standards, which means that NCLFR-Oil's conceptual design is acceptable and the reactor has excellent safety characteristics.

Genotypic and Phenotypic Characterization of Some psms Hypervirulent Clinical Isolates of Staphylococcus aureus in a Tertiary Hospital in Hefei, Anhui.

Staphylococcus aureus is a highly successful pathogen that can cause various infectious diseases, from relatively mild skin infections to life-threatening severe systemic diseases. The widespread pathogenicity of S. aureus is mainly due to its ability to produce many virulence factors that help destroy various host cells, causing disease. Our primary goal in this study was to explore the genes of highly virulent strains, to identify genes closely associated with high virulence, and to provide ideas for the treatment of infection by highly virulent clinical strains. This study collected 221 clinical strains from The First Affiliated Hospital Of The University of Science and Technology of China (USTC); their hemolytic abilities were tested. Eight isolates were selected based on their highly hemolytic ability and tested their hemolytic activity again; their phenotypes and gene sequences were also explored. Whole-genome sequencing (WGS) showed six plasmids (pN315, pNE131, pSJH901, pSJH101, SAP106B, and MSSA476), eight antibiotic resistance genes [blaR1, blaI, blaZ, mecA, erm(C), erm(T), tet(38), and fosB-Saur] and seventy-two virulence related genes. Three highly virulent strains, namely X21111206, 21092239, and 21112607, were found according the Galleria mellonella infection model. Therefore, we selected 10 representative virulence genes for qRT-PCR: psmα, psmβ, hlgA, hlgB, hlgC, hla, clfA, clfB, spa, and sak. Among them, the expression levels of psmα and psmβ, the three isolates, were significantly higher than the positive control NCTC8325. Significant differences appear in the expression of virulence genes in the highly virulent strains, particularly the psmα and psmβ, It may be that the high expression of psm gene is the cause of the high virulence of Staphylococcus aureus. We can reduce the pathogenicity of Staphylococcus aureus by inhibiting the expression of psm gene, which may provide a strong basis for psm as a new target for clinical treatment of S. aureus infection.

Design of a megawatt superradiant terahertz source for FELiChEM

FELiChEM is an infrared free electron laser user facility built at the University of Science and Technology of China (USTC). It consists of two free electron laser oscillators which produce mid-infrared and far-infrared lasers covering the spectral range of 2–200 μm at current stage. In this paper, we propose a new operation mode of a megawatt (MW) terahertz (THz) superradiance free electron laser (FEL) for FELiChEM. Start-to-end (S2E) simulations have been carried out, in which the three-dimension particle-in-cell (PIC) code PUFFIN is used for the generation of the THz superradiance. Simulation results demonstrate that this superradiant FEL can provide 100–1000 μm laser with MW-class peak power from a 1.2 meter single-pass undulator when the electron energy is around 15 MeV.

Observation of MLT region winds and tides by the USTC Mengcheng meteor radar

The atmospheric winds and waves in the mesosphere and lower thermosphere (MLT) region are essential for studying the dynamics and climate in the middle and upper atmosphere. The University of Science and Technology of China (USTC) meteor radar located at Mengcheng (33.36°N, 116.49°E) has been operating continuously since April 2014. More than 8 years of observation of mesospheric horizontal winds and tides are presented in this study. In addition, we present an intercomparison among the meteor radar observations and the Navy Global Environmental Model-High Altitude (NAVGEM-HA) analysis results. The meteor number at northern lower midlatitudes suffers from diurnal variations in meteor occurrence, with a high count rate in the local morning and a low rate during local afternoon-to-midnight. The meteor count rates show a clear annual variation, with a maximum in September–October and a minimum in February. The horizontal wind in the MLT region has dominant annual variations at lower midlatitudes, with the eastward wind during summer and the westward wind during winter above 84 km, and the eastward wind during winter and the westward wind during spring below 84 km. The meridional wind is northward during winter and southward during summer. The diurnal amplitude is dominant, followed by the semidiurnal tides at lower midlatitudes. The zonal and meridional diurnal tides show enhancements during spring (March) with amplitudes that can reach up to 40 m/s and 30 m/s and during autumn (September) with amplitudes that can reach up to 30 m/s and 25 m/s, respectively. The seasonal variations in diurnal tidal amplitude basically show characteristics that are strong during the equinox and weak during the solstice. The zonal and meridional semidiurnal tides are maximized during spring (April) and autumn (September) above 90 km.

IEEE SSCS University of Science and Technology of China Student Branch Chapter Wins Outstanding Chapter of the Year and Holds Numerous Events [Chapters

The IEEE Solid-State Circuits Society (SSCS) University of Science and Technology of China (USTC) Student Branch Chapter (SBC) won the SSCS Student Branch Chapter of the Year award. The award was received by Chapter Advisor Prof. Fujiang Lin during the Chapter Chair Luncheon at the International Solid-State Circuits Conference, on 21 February 2023.

Association between lesion location and depressive symptoms in acute ischemic stroke patients using voxel-based lesion-symptom mapping

Objective: The study aimed to investigate the association between lesion location and post-stroke depression (PSD) in acute ischemic stroke patients. Methods: In this case-control study, acute ischemic stroke patients were recruited from the Department of Neurology, First Affiliated Hospital of the University of Science and Technology of China (USTC), between September 2020 and June 2021. According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) criteria, the patients were divided into the PSD and non-PSD groups. The 24-item Hamilton Rating Scale (HAMD) was used to evaluate the severity of depression. The Student's t-test, Mann-Whitney test, and Chi-square test were used to compare the clinical baseline characteristics of PSD and non-PSD groups. Voxel-based lesion-symptom mapping (VLSM) was applied to investigate the association between lesion location and depression occurrence and severity. Results: A total of 70 and 173 patients were admitted to the PSD and non-PSD groups, respectively. The mean age of patients was 59 years (23-86). There were 153 males and 90 females. Univariate analysis showed a significant difference only in Hamilton Anxiety (P=0.025) and Depression (P<0.001) scores between the PSD and non-PSD groups. VLSM analysis identified clusters within the anterior cingulate gyrus (Z=-3.05, P<0.001), left hippocampus (Z=-3.15, P<0.001), and left lingual lobe (Z=-3.08, P<0.001) where lesions were significantly associated with PSD. Additionally, the severity of PSD was associated with damage in the anterior cingulate gyrus (Z=-3.64, P<0.001), left hippocampus (Z=-3.51, P<0.001), left lingual lobe (Z=-4.18, P<0.001), and pericalcarine cortex (Z=-3.65, P<0.001). Conclusion: VLSM demonstrated that lesion location could be used to predict the occurrence of PSD in patients with acute ischemic stroke.

Ground-Based Hyperspectral Stereoscopic Remote Sensing Network: A Promising Strategy to Learn Coordinated Control of O3 and PM2.5 over China

With the coming of the “14th Five-Year Plan”, the coordinated control of particulate matter with an aerodynamic diameter no greater than 2.5 μm (PM 2.5 ) and O 3 has become a major issue of air pollution prevention and control in China. The stereoscopic monitoring of regional PM 2.5 and O 3 and their precursors is crucial to achieve coordinated control. However, current monitoring networks are currently inadequate for monitoring the vertical profiles of both PM 2.5 and O 3 simultaneously and support air quality control. The University of Science and Technology of China (USTC) has established a nationwide ground-based hyperspectral stereoscopic remote sensing network based on multi-axis differential optical absorption spectroscopy (MAX-DOAS) since 2015. This monitoring network provides a significant opportunity for the regional coordinated control of PM 2.5 and O 3 in China. One-year vertical profiles of aerosol, NO 2 and HCHO monitored from four MAX-DOAS stations installed in four megacities (Beijing, Shanghai, Shenzhen, and Chongqing) were used to characterize their vertical distribution differences in four key regions, Jing–Jin–Ji (JJJ), Yangtze River Delta (YRD), Pearl River Delta (PRD), and Sichuan Basin (SB), respectively. The normalized and yearly averaged aerosol vertical profiles below 400 m in JJJ and PRD exhibit a box shape and a Gaussian shape, respectively, and both show exponential shapes in YRD and SB. The NO 2 vertical profiles in four regions all exhibit exponential shapes because of vehicle emissions. The shape of the HCHO vertical profile in JJJ and PRD was Gaussian, whereas an exponential shape was shown in YRD and SB. Moreover, a regional transport event occurred at an altitude of 600–1000 m was monitored in the southwest–northeast pathway of the North China Plain (NCP) by five MAX-DOAS stations (Shijiazhuang (SJZ), Wangdu (WD), Nancheng (NC), Chinese Academy of Meteorological Sciences (CAMS), and University of Chinese Academy of Sciences (UCAS)) belonging to the above network. The aerosol optical depths (AOD) in these five stations decreased in the order of SJZ > WD > NC > CAMS > UCAS. The short-distance regional transport of NO 2 in the 700–900 m layer was monitored between WD and NC. As an important precursor of secondary aerosol, the peak of NO 2 air mass in WD and NC all occurred 1 h earlier than that of aerosol. This was also observed for the short-distance regional transport of HCHO in the 700–900 m layer between NC and CAMS, which potentially affected the O 3 concentration in Beijing. Finally, CAMS was selected as a typical site to determine the O 3 –NO x –volatile organic compounds (VOCs) sensitivities in vertical space. We found the production of O 3 changed from predominantly VOCs-limited conditions to mainly mixed VOCs–NO x -limited condition from the 0–100 m layer to the 200–300 m layer. In addition, the downward transport of O 3 could contribute to the increase of ground surface O 3 concentration. This ground-based hyperspectral stereoscopic remote sensing network provide a promising strategy to support management of PM 2.5 and O 3 and their precursors and conduct attribution of sources.

A Review of Computational Phantoms for Quality Assurance in Radiology and Radiotherapy in the Deep-Learning Era

The exciting advancement related to the “modeling of digital human” in terms of a computational phantom for radiation dose calculations has to do with the latest hype related to deep learning. The advent of deep learning or artificial intelligence (AI) technology involving convolutional neural networks has brought an unprecedented level of innovation to the field of organ segmentation. In addition, graphics processing units (GPUs) are utilized as boosters for both real-time Monte Carlo simulations and AI-based image segmentation applications. These advancements provide the feasibility of creating three-dimensional (3D) geometric details of the human anatomy from tomographic imaging and performing Monte Carlo radiation transport simulations using increasingly fast and inexpensive computers. This review first introduces the history of three types of computational human phantoms: stylized medical internal radiation dosimetry (MIRD) phantoms, voxelized tomographic phantoms, and boundary representation (BREP) deformable phantoms. Then, the development of a person-specific phantom is demonstrated by introducing AI-based organ autosegmentation technology. Next, a new development in GPU-based Monte Carlo radiation dose calculations is introduced. Examples of applying computational phantoms and a new Monte Carlo code named ARCHER (Accelerated Radiation- transport Computations in Heterogeneous EnviRonments) to problems in radiation protection, imaging, and radiotherapy are presented from research projects performed by students at the Rensselaer Polytechnic Institute (RPI) and University of Science and Technology of China (USTC). Finally, this review discusses challenges and future research opportunities. We found that, owing to the latest computer hardware and AI technology, computational human body models are moving closer to real human anatomy structures for accurate radiation dose calculations.

Comparison of Lower Stratosphere Wind Observations From the USTC's Rayleigh Doppler Lidar and the ESA's Satellite Mission Aeolus

AbstractSince the first spaceborne Doppler wind lidar, Aeolus, was launched, global wind field observations from space have been possible. Several ground‐ and air‐based validations followed, although most of these comparisons remained below 10 km in the troposphere, with rare validation work for the stratosphere. The Rayleigh Doppler lidar developed by the University of Science and Technology of China (USTC) was deployed in Xinjiang, China, in 2017. It can observe wind speed and temperature in the stratosphere and mesosphere. By setting two geographical ranges centered on the USTC lidar, the Aeolus Rayleigh winds within these ranges can be compared with ground‐based lidar wind data. Furthermore, after eliminating the effect of particulate backscatter on the USTC lidar, the lower limit of the detection range was extended to 10 km to obtain more samples. The mean biases between the Aeolus winds and the USTC lidar winds were 1.05 ± 5.98 (−0.35 ± 4.78) m/s, 1.80 ± 6.30 (−1.88 ± 4.97) m/s, and 0.17 ± 5.45 (0.51 ± 4.44) m/s for all data, ascending orbits, and descending orbits, respectively, in a large (small) geographical range. The geographical distance between the USTC lidar and the Aeolus observation swaths has a significant effect on the wind bias, the farther the distance between Aeolus observation swaths and the USTC lidar, the greater the bias. Whereas, the wind biases have no significant dependency on the time difference of the USTC lidar observation to Aeolus overflight time. Overall, the Aeolus winds are consistent with the USTC lidar winds in the stratosphere.

Digital low-level RF system for the infrared free-electron laser facility

The infrared free-electron laser facility (IR-FEL) is a new free-electron oscillator user facility in the University of Science and Technology of China (USTC), which has come into user operation in September 2021. To get a low energy spread electron beam, we designed and fabricated a digital low-level radio frequency system (DLLRF) based on the MTCA.4 platform to monitor and control the microwave field. The simulation for RF system is implemented to estimate the feedback coefficients and analyze the influence of driving chain noise and measurement noise in this case. Beam tests show that the pulse-to-pulse PI feedback eliminates the slow drift effectively and improves the stability of the phase from 3.4° to 0.19° (RMS). The application of the PI-type feed-forward decreases intra-pulse ripples of phase from 5° to 1° (peak to peak).

Impacts of TROPOMI-Derived NO X Emissions on NO2 and O3 Simulations in the NCP during COVID-19.

NO2 and O3 simulations have great uncertainties during the COVID-19 epidemic, but their biases and spatial distributions can be improved with NO2 assimilations. This study adopted two top-down NO X inversions and estimated their impacts on NO2 and O3 simulation for three periods: the normal operation period (P1), the epidemic lockdown period following the Spring Festival (P2), and back to work period (P3) in the North China Plain (NCP). Two TROPOspheric Monitoring Instrument (TROPOMI) NO2 retrievals came from the Royal Netherlands Meteorological Institute (KNMI) and the University of Science and Technology of China (USTC), respectively. Compared to the prior NO X emissions, the two TROPOMI posteriors greatly reduced the biases between simulations with in situ measurements (NO2 MREs: prior 85%, KNMI -27%, USTC -15%; O3 MREs: Prior -39%, KNMI 18%, USTC 11%). The NO X budgets from the USTC posterior were 17-31% higher than those from the KNMI one. Consequently, surface NO2 levels constrained by USTC-TROPOMI were 9-20% higher than those by the KNMI one, and O3 is 6-12% lower. Moreover, USTC posterior simulations showed more significant changes in adjacent periods (surface NO2: P2 vs P1, -46%, P3 vs P2, +25%; surface O3: P2 vs P1, +75%, P3 vs P2, +18%) than the KNMI one. For the transport flux in Beijing (BJ), the O3 flux differed by 5-6% between the two posteriori simulations, but the difference of NO2 flux between P2 and P3 was significant, where the USTC posterior NO2 flux was 1.5-2 times higher than the KNMI one. Overall, our results highlight the discrepancies in NO2 and O3 simulations constrained by two TROPOMI products and demonstrate that the USTC posterior has lower bias in the NCP during COVD-19.