A dosimetric evaluation of flattening filter-free volumetric modulated arc therapy for postoperative treatment of cervical cancer

Objective The aim of the study was to compare flattening filter-free(FFF) beams and conventional flattening filter(FF) beams in volumetric modulated arc therapy(VMAT) for cervical cancer after surgery, through a retrospective planning study.Methods VMAT plans of FFF beams and normal FF beams were designed for a cohort of 15 patients. The prescribed dose was 45 Gy to 1.8 Gy per fraction, and at least 95% of the planning target volume received this dose. Doses were computed with a commercially available treatment planning system using a Monte Carlo(MC) algorithm. Plans were compared according to dose-volume histogram analysis in terms of planning target volume homogeneity and conformity indices(HI and CI), as well as organs at risk(OAR) dose and volume parameters. Results FFF-VMAT was similar to FF-VMAT in terms of CI, but inferior to FF-VMAT considering HI. No statistically differences were observed between FFF-VMAT and FF-VMAT in following organ at risks including pelvic bone marrow, small bowel, bladder, rectum, and normal tissue(NT)..Conclusion For patients with cervical cancer after hysterectomy, the FFF beam achieved target and OAR dose distribution similar to that of the FF beam. Reduction of beam-on time in cervical cancer is beneficial.

食管鳞癌患者根治性放疗预后列线图模型的构建—泛京津冀多中心回顾分析(3JECROG R-03A)

目的:构建列线图(nomogram)模型以预测食管鳞癌患者的预后情况,指导个体化治疗。方法:回顾性分析2002年1月至2016年12月国内10家放疗中心(泛京津冀食管癌协作组-3JECROG)收治的2680例根治性放疗食管鳞癌患者资料,随机分为训练组和验证组,根据训练组的预后因素构建nomogram模型,并进行训练组内部和验证组外部验证。分别以nomogram模型与AJCC/UICC分期评估两组患者预后及临床获益。结果:全组1、3、5年生存率分别为69.0%、37.7%、31.0%。多因素分析肿瘤部位、TNM分期、原发肿瘤体积和是否同步化疗是影响食管癌的独立预后因素(均P<0.05)。在训练组和验证组中nomogram模型的一致性指数(C-index)、AUC值均高于AJCC/UICC分期(均P<0.001)。基于nomogram模型分为低、中、高风险亚组与AJCC/UICC分期比较,nomogram模型的生存曲线之间具有显著性差异(P<0.001),且1、3、5年的总生存临床决策曲线(decision curve analysis,DCA)下面积均具有显著性差异。结论:本研究构建的nomogram模型较AJCC/UICC分期具有更好的预测能力,有助于食管癌患者的预后判断及指导个体化治疗。

气候变化对黄河源区的水文影响分析

近年来,黄河源区由于受到气候变化和人类活动的影响,生态系统和水文情势均发生显著变化。本文就气候变化对黄河源区的影响展开调查,分析了源区的气温的变化趋势及突变年代,降水的季节分配和变化趋势,以及径流的年内变化和年际变化。本文通过计算径流年内分配不均匀系数判断径流分配均匀性,通过分析滑动平均序列的曲线判断整个时间序列的趋势,通过累积距平曲线的变化判断序列大致突变的时间以及长期持续变化情况和演变趋势。结果表明：在气候因子变化分析中,在1960-2014年长时间序列中,黄河源区年平均气温呈现显著增加趋势。根据降水变化分析结果,黄河源区降水年内分配差异较大,在年际变化上,降水量整体呈现不显著的增加趋势。黄河源区径流量不均匀系数较大,集中度较高,说明径流分配有明显的丰枯季节变化。径流量整体呈现减少的趋势,这种趋势在90年代至21世纪中期尤为明显。

Multi-Cluster Feature Selection Based on Isometric Mapping

Dear editor,This letter presents an unsupervised feature selection method based on machine learning.Feature selection is an important component of artificial intelligence,machine learning,which can effectively solve the curse of dimensionality problem.Since most of the labeled data is expensive to obtain.

Diverse Structural Design Strategies of MXene‑Based Macrostructure for High‑Performance Electromagnetic Interference Shielding

There is an urgent demand for flexible,lightweight,mechanically robust,excellent electromagnetic interference(EMI)shielding materials.Two-dimensional(2D)transition metal carbides/nitrides(MXenes)have been potential candidates for the construction of excellent EMI shielding materials due to their great electrical electroconductibility,favorable mechanical nature such as flexibility,large aspect ratios,and simple processability in aqueous media.The applicability of MXenes for EMI shielding has been intensively explored;thus,reviewing the relevant research is beneficial for advancing the design of high-performance MXene-based EMI shields.Herein,recent progress in MXene-based macrostructure development is reviewed,including the associated EMI shielding mechanisms.In particular,various structural design strategies for MXene-based EMI shielding materials are highlighted and explored.In the end,the difficulties and views for the future growth of MXene-based EMI shields are proposed.This review aims to drive the growth of high-performance MXene-based EMI shielding macrostructures on basis of rational structural design and the future high-efficiency utilization of MXene.

Dosimetric evaluation of VMAT radiation therapy technique for breast cancer after conservative surgery based on three different types of multileaf collimators

Objective Radiotherapy combined with conservative surgery plays an important role in the treatment of early-stage breast cancer. Volumetric modulated arc therapy(VMAT) has been introduced into clinical practice. The purpose of this study was to investigate the dosimetric effects of different multileaf collimators(MLC) on VMAT radiotherapy plans for treating breast cancer.Methods Fifteen breast cancer patients who were treated using a conventional technique in our department were selected to participate in this retrospective analysis. VMAT plans based on three types of Elekta MLCs [Beam Modulator(BM) with 4-mm leaf width, Agility with 5-mm leaf width and MLCi2 with 10-mm leaf width] were independently generated for each patient. Plan comparisons were performed based on dose-volume histogram(DVH) analysis including dosimetric parameters such as the homogeneity index(HI), conformity index(CI), Dmax, Dmin, and Dmean for the planning treatment volume(PTV), in addition to dose-volume parameters for the organs at risk(OARs). The delivery efficiency of the three types of MLCs was compared in terms of the beam delivery time and the monitor units(MUs) per fraction for each plan. Results Both target uniformity and conformity were improved in plans for Agility and BM MLC compared with the plan using MLCi2. The mean HI decreased from 1.14 for MLCi2 to 1.13 for BM and 1.10 for Agility, while the mean CI increased from 0.68 for MLCi2 to 0.73 for BM and 0.75 for Agility. Furthermore, at both low and high dose levels, smaller volumes of ipsilateral lung, heart, contralateral lung, and breast were irradiated with Agility MLC than with the other two types of MLCs. The delivery time with Agility MLC was reduced by 10.8% and 32.1%, respectively, compared with that for MLCi2 and BM.Conclusion Our results indicate that the Agility MLC exhibits a dosimetric advantage and a significant improvement in delivery efficiency for the treatment of breast cancer using VMAT.

Comparison of the effects of two typesof multileaf collimators on tumor control probabilityin radiotherapy for breast cancer after conservativesurgery based on the EUD model

Objective To compute and compare the tumor control probability(TCP) of volumetric modulated arc therapy(VMAT) for breast cancer after conservative surgery based on two types of multileaf collimator(MLC) through a retrospective planning study.Methods For a group of 9 patients diagnosed with left breast cancer,VMAT plan based on Agility MLC and beam modulator(BM) MLC were designed.The prescription dose was 50 Gy covering at least 95% of the planning target volume,2 Gy per fraction.TCPs were calculated according to dose-volume histogram(DVH) analysis.Results The TCP of the BM VMAT plan was slightly higher than that of the Agility VMAT plan(94.61% vs 94.23%) but was inferior with respect to delivery efficiency;the delivery time was reduced for Agility VMAT plan by 35% compared to BM VMAT plan.Conclusion For breast cancer radiation therapy after conservative surgery,BM VMAT plans provide slightly higher TCP while the delivery of Agility VMAT plans is significantly faster than the BM VMAT plans.

Automatic delineation of organs at risk in non-small cell lung cancer radiotherapy based on deep learning networks

Objective To introduce an end-to-end automatic segmentation method for organs at risk(OARs)in chest computed tomography(CT)images based on dense connection deep learning and to provide an accurate auto-segmentation model to reduce the workload on radiation oncologists.Methods CT images of 36 lung cancer cases were included in this study.Of these,27 cases were randomly selected as the training set,six cases as the validation set,and nine cases as the testing set.The left and right lungs,cord,and heart were auto-segmented,and the training time was set to approximately 5 h.The testing set was evaluated using geometric metrics including the Dice similarity coefficient(DSC),95%Hausdorff distance(HD95),and average surface distance(ASD).Thereafter,two sets of treatment plans were optimized based on manually contoured OARs and automatically contoured OARs,respectively.Dosimetric parameters including Dmax and Vx of the OARs were obtained and compared.Results The proposed model was superior to U-Net in terms of the DSC,HD95,and ASD,although there was no significant difference in the segmentation results yielded by both networks(P>0.05).Compared to manual segmentation,auto-segmentation significantly reduced the segmentation time by nearly 40.7%(P<0.05).Moreover,the differences in dose-volume parameters between the two sets of plans were not statistically significant(P>0.05).Conclusion The bilateral lung,cord,and heart could be accurately delineated using the DenseNet-based deep learning method.Thus,feature map reuse can be a novel approach to medical image auto-segmentation.

Application of biological optimization of hypofractionated radiotherapy post conservative surgery for breast cancer

Objective The aim of the study was to discuss the application of biological optimization and its difference from physical optimization in hypofractionated radiotherapy for breast cancer after conservative surgery.Methods This retrospective study enrolled 15 randomly chosen patients with left-sided breast cancer who received radiotherapy.The volumetric arc therapy(VMAT)technique was used to redesign treatment plans with physical functions(PF)group,biological-physical functions combined(BF+PF and PF+BF)groups,and biological functions(BF)group.The dosimetric differences based on the above four optimization methods were assessed by calculating and analyzing the corresponding dose-volume parameters.Results The target parameters of the four groups differed significantly(P<0.05)except for the conformity index(CI).The tumor control probability(TCP)values in the BF and BF+PF groups were higher than those in the PF and PF+BF groups.Moreover,the dose-volume parameters of the ipsilateral lung in the BF group were less than those of three other groups,while the monitor unit(MU)in the BF group was approximately 16%lower than those of the PF and PF+BF groups.Conclusion Biological functions were useful to increase the equivalent uniform dose(EUD)and TCP values of the target,decrease the dose-volume parameters of the organs-at-risk(OARs),and improve treatment efficiency.

Dosimetric evaluation of CR, 3DCRT and two types of IMRT for breast cancer after conservative surgery

Objective: The purpose of this study was to compare the dose distribution and dose volume histogram (DVH) of the planning target volume (PTV) and organs at risk (OARs) among conventional radiation therapy (CR), three-dimensional conformal radiation therapy (3DCRT), two-step intensity-modulated radiation therapy (TS-IMRT) and direct machine parameter optimization intensity-modulated radiation therapy (DMPO-IMRT) after breast-conserving surgery. Methods: For each of 20 randomly chosen patients, 4 plans were designed using 4 irradiation techniques. The prescribed dose was 50 Gy/2 Gy/25 f, 95% of the planning target volume received this dose. The cumulated DVHs and 3D dose distributions of CR, 3DCRT, TS-IMRT and DMPO-IMRT plans were compared. Results: For the homogeneity indices, no statistically significant difference was observed among CR, 3DCRT, TS-IMRT and DMPO-IMRT while the difference of the conformality indices were statistically significant. With regard to the organs at risk, IMRT and 3DCRT showed a significantly fewer exposure dose to the ipsilateral lung than CR in the high-dose area while in the low-dose area, IMRT demonstrated a significant increase of exposure dose to ipsilateral lung, heart and contralateral breast compared with 3DCRT and CR. In addition, the monitor units (MUs) for DMPO-IMRT were approximately 26% more than those of TS-IMRT and the segments of the former were approximately 24% less than those of the latter. Conclusion: Compared with CR, 3DCRT and IMRT improved the homogeneity and conformity of PTV, reduced the irradiated volume of OARs in high dose area but IMRT increased the irradiated volume of OARs in low dose area. DMPO-IMRT plan has fewer delivery time but more MUs than TS-IMRT.

Phantom-based evaluations of two binning algorithms for four-dimensional CT reconstruction in lung cancer radiation therapy

Objective: The purpose of this study was to evaluate the performance of the phase-binning algorithm and amplitude-binning algorithm for four-dimensional computed tomography(4DCT) reconstruction in lung cancer radiation therapy. Methods: Quasar phantom data were used for evaluation. A phantom of known geometry was mounted on a four-dimensional(4D) motion platform programmed with twelve respiratory waves(twelve lung patients trajectories) and scanned with a Philips Brilliance Big bore 16-slice CT simulator. The 4DCT images were reconstructed using both phase- and amplitude-binning algorithms. Internal target volumes(ITVs) of the phase- and amplitude-binned image sets were compared by evaluation of shape and volume distortions. Results: The phantom experiments illustrated that, as expected, maximum inhalation occurred at the 0% amplitude and maximum exhalation occurred at the 50% amplitude of the amplitude-binned 4DCT image sets. The amplitude-binned algorithm rendered smaller ITV than the phase-binning algorithm. Conclusion: The amplitude-binning algorithm for 4DCT reconstruction may have a potential advantage in reducing the margin and protecting normal lung tissue from unnecessary irradiation.

Five-year oncologic outcomes and prognostic factors for locally advanced low rectal cancer after low anterior resection

Objective： The aim of the study is to investigate the longterm oncologic outcomes including local recurrence, distant metastases and overall survival （OS） for patients with low rectal cancer underwent low anterior resection （LAR） with total mesorectal excision （TME）, and to analyze the prognostic factors for them. Methods： Between January 2001 and December 2009, 147 patients with clinical stage II and III rectal cancers located 3-6 cm from the anal verge underwent LAR with TME without temporary diverting stoma. The median distal resection margin （DRM） was 1.0 （range, 0.3-5） cm. Anastomostic leakage occurred in 29 （19.7%） patients. Thirty patients received surgery alone, 20 patients received preoperative chemoradiotherapy （CRT）, 43 patients received postoperative CRT, and adjuvant chemotherapy was administered for 108 patients. The median cycle of adjuvant chemotherapy was 6 （range, 2-20） cycles. The median followup was 74.8 （range, 30.1-146.3） months. Results： In all patients, 5-year recurrence-free survival （RFS）, disease-free survival （DFS） and OS were 70.4%, 54.2% and 60.5%, respectively. Forty-three （29.3%） patients suffered local recurrence. Patients received preoperative CRT with a downstaging yp0/1 who had a better 5-year RFS, DFS and OS, which were 100%, 90.9%, and 90.9%, respectively. For patients with pathologic stage Ⅱ and stage Ⅲ, the 5-year RFS, DFS, and OS were 79.2% and 60.1%, 67.9% and 39.1%, 72.1% and 48.2%, respectively. On multivariable analysis, RFS was associated with anostomostic leakage, DFS was associated with anastomostic leakage and pathologic N stage, and OS was associated with anastomostic leakage, pathologic N and T stage. For patients with anastomostic leakage, the 5-year RFS, DFS, and OS were 51.7%, 32.4%, and 38.3%, respectively, which were worse than that for patients without anastomostic leakage, the latter were 75.2%, 59.7%, 65.7%, respectively （P 〈 0.05）. DRM and radiotherapy were associated with RFS on univariable analysis （P 〈 0.05）, but not on multivariable analysis. Tumor grade was prognostic factors for RFS and OS on univariable analysis, but not on multivariable analysis. The other factors including sex, age, tumor size and adjuvant chemotherapy were not associated with RFS, DFS and OS on univariable analysis. Conclusion： For patients with low rectal caner underwent LAR and TME, the long-term oncologic outcomes were satisfactory for patients with stage yp0/1, but not for patients with pathologic stage II1. Anastomositic leakage negatively affect long-term oncologic outcomes. Radiotherpy, adjuvant chemotherapy and distal resection margin were not associated with long-term outcomes.

Dosimetric analysis of tomotherapy-based intensity-modulated radiotherapy with and without bone marrow sparing for the treatment of cervical cancer

Objective The aim of the study was to compare tomotherapy-based bone marrow-sparing intensity-mod- ulated radiotherapy （BMS-IMRT） with intensity-modulated radiotherapy （IMRT） without entering the pelvic bone marrow as a planning constraint in the treatment of cervical cancer after hysterectomy. Methods BMS-IMRT and IMRT plans were designed for a cohort of nine patients. The prescribed dose was 45 Gy in 1.8 Gy daily fractions, and 95% of the planned target volume received this dose. The doses were computed using a commercially available treatment planning system with the convolution/superposition algorithm. Plans were compared according to dose-volume histogram analysis in terms of planning target volume homogeneity and conformity indices （HI and CI） as well as organ at risk dose and volume parameters. Results BMS-IMRT had advantages over IMRT in terms of CI, but was equivalent to the latter in H1. V5, V10, V20, V30, and V40 of pelvic bone marrow in BMS-IMRT decreased by 0.06%, 17.33%, 22.19%, 13.85%, and 16.46%, respectively, compared with IMRT. Except for V30 of the small bowel and V30 and V40 of the bladder, no statistically significant differences were found between BMS-IMRT and IMRT in the small bowel, bladder, and rectum. Conclusion For cervical cancer patients receiving tomotherapy-based radiotherapy after hysterectomy, BMS-IMRT reduced pelvic bone marrow volume receiving low-dose radiation, and it may be conducive to preventing acute hematologic toxicity.

Multi‐granularity re‐ranking for visible‐infrared person re‐identification

Visible‐infrared person re‐identification(VI‐ReID)is a supplementary task of single‐modality re‐identification,which makes up for the defect of conventional re‐identification under insufficient illumination.It is more challenging than single‐modality ReID because,in addition to difficulties in pedestrian posture,camera shoot-ing angle and background change,there are also difficulties in the cross‐modality gap.Existing works only involve coarse‐grained global features in the re‐ranking calculation,which cannot effectively use fine‐grained features.However,fine‐grained features are particularly important due to the lack of information in cross‐modality re‐ID.To this end,the Q‐center Multi‐granularity K‐reciprocal Re‐ranking Algorithm(termed QCMR)is proposed,including a Q‐nearest neighbour centre encoder(termed QNC)and a Multi‐granularity K‐reciprocal Encoder(termed MGK)for a more comprehensive feature representation.QNC converts the probe‐corresponding modality features into gallery corresponding modality features through modality transfer to narrow the modality gap.MGK takes a coarse‐grained mutual nearest neighbour as the dominant and combines a fine‐grained nearest neighbour as a supplement for similarity measurement.Extensive experiments on two widely used VI‐ReID benchmarks,SYSU‐MM01 and RegDB have shown that our method achieves state‐of‐the‐art results.Especially,the mAP of SYSU‐MM01 is increased by 5.9%in all‐search mode.

Dosimetric comparison of different multileaf collimators in volumetric modulated arc therapy for malignant pleural mesothelioma

Objective The aiom of the study was to compare the impacts of two types of multileaf collimators （MLC） [standard MLC with a width of 10 mm （sMLC） and micro-MLC with a width of 5 mm （mMLC）] on volumetric modulated arc therapy （VMAT） planning for malignant pleural mesothelioma. Methods VMAT for ten patients with inoperable malignant pleural mesotheliomas was retrospectively planned with the sMLC and mMLC. Histogram-based dose-volume parameters of the planning target vol- ume （PTV） [conformity index （CI） and homogeneous index （HI）] and organs-at-risk were compared for VMAT plans with sMLC （sMLC-VMAT） and mMLC （mMLC-VMAT）. Results The mMLC-VMAT plans were more efficient （average delivery time： 2.67±1.49 min） than the sMLC-VMAT plans （average delivery time： 4.21 ± 2.03 min; P 〈 0.05）. Moreover, compared to the sMLC plans, the mMLC plans demonstrated advantages in the dose coverage of the PTV （CI 0.75 ± 0.08 vs 0.73± 0.09; HI 1.09 ±0.02 vs 1.10± 0.02）, although the difference was not statistically significant （P 〉 0.05）. In addition, significant dose sparing in the fraction of the ipsilateral lung volume receiving 〉 20 Gy （V20; 54.72± 27.08 vs 58.52 ± 29.30） and 〉 30 Gy （V30; 42.74 ± 27.86 vs 46.86± 31.49） radiation, respectively, was observed for the mMLC plans （P 〈 0.05）. Conclusion Comparing sMLC-VMAT and mMLC-VMAT not only demonstrated the higher efficiency and better optimal target coverage of mMLC-VMAT, but also considerably improved the dose sparing of the ipsilateral lung in the VMAT plans for mali qnant pleural mesothelioma.

Application Effect of Informationized Teaching Method Based on Evidence-based Nursing in Surgical Nursing Teaching

Objective:The study was to analyze the application effect of informationized teaching method based on evidence-based nursing in surgical nursing teaching.Methods:From December 2019 to December 2020,60 students were selected as the research objects and randomly divided into two groups,each with 30 students in the teaching group.The observation group applied informationized teaching based on evidence-based nursing method,and the control group used the traditional teaching model.The teaching effect was evaluated.Results:The test scores of subjective theoretical knowledge and objective theoretical knowledge of the observation group were significantly higher than those of the control group,and the comprehensive ability evaluation of the observation group was also higher(P<0.05).The majority of students accepted the informationized teaching method based on evidence-based nursing,and a few held a neutral or disapproval attitude.Conclusion:Informationized teaching method based on evidencebased nursing can improve students'theoretical and practical levels in surgical nursing teaching,and most students also accept this teaching method,which has application value.

Progress and challenge of functional single-atom catalysts for the catalytic oxidation of volatile organic compounds

The catalytic oxidation of volatile organic compounds(VOCs)is of considerable significance for the sustainable development of the chemical industry;thus,considerable efforts have been devoted to the exploration of efficient catalysts for use in this reaction.In this regard,the development and utilization of single-atom catalysts(SACs)in VOCs decomposition is a rapidly expanding research area.SACs can be employed as potential catalysts for oxidizing VOC molecules due to their optimal utilization efficiency,unique atomic bonding structures,and unsaturated orbits.Progress has been achieved,while the challenges surrounding precise regulation of the microstructures of SACs for improving their low-temperature efficiency,stability,and product selectivity under practical conditions are remaining.Therefore,elucidating structure-performance relationships and establishing intrinsic modulating mechanisms are urgently required for guiding researchers on how to synthesize effective and stable functional SACs proactively.Herein,recent advances in the design and synthesis of functional SACs for application in the catalytic oxidation of VOCs are summarized.The experimental and theoretical studies revealing higher efficiency,stability,and selectivity of as-prepared functional SACs are being highlighted.Accordingly,the future perspectives in terms of promising catalysts with multi-sized composite active sites and the illustration of intrinsic mechanism are proposed.The rapid intelligent screening of applicable SACs and their industrial applications are also discussed.

Polarization-dependent photoinduced metal–insulator transitions in manganites

In correlated oxides,collaborative manipulation on light intensity,wavelength,pulse duration and polarization has yielded many exotic discoveries,such as phase transitions and novel quantum states.In view of potential optoelectronic applications,tailoring long-lived static properties by light-induced effects is highly desirable.So far,the polarization state of light has rarely been reported as a control parameter for this purpose.Here,we report polarization-dependent metal-to-insulator transition(MIT)in phaseseparated manganite thin films,introducing a new degree of freedom to control static MIT.Specifically,we observed giant photoinduced resistance jumps with striking features:(1)a single resistance jump occurs upon a linearly polarized light incident with a chosen polarization angle,and a second resistance jump occurs when the polarization angle changes;(2)the amplitude of the second resistance jump depends sensitively on the actual change of the polarization angles.Linear transmittance measurements reveal that the origin of the above phenomena is closely related to the coexistence of anisotropic micro-domains.Our results represent a first step to utilize light polarization as an active knob to manipulate static phase transitions,pointing towards new pathways for nonvolatile optoelectronic devices and sensors.

Experiment and simulation study of emergency evacuation during violent attack in classrooms

In recent years,as a disaster,terrorist attacks have occurred throughout the world.However,emergency evac-uation behaviors during these incidents were not clear,and the traditional emergency plans were not suitable for such incidents.In this paper,evacuation behaviors under armed assault attack in a classroom were studied based on evacuation experiments.A total of 103 participants took part in three experiments.In each experiment,the attacker’s attacking route was set differently to study the impact of the attacking route on evacuation be-haviors.Pre-evacuation delay,panic of the evacuees,exit choices,evacuation time,and evacuees’trajectories in the experiments were all analyzed.The results of the experiments showed that when a terrorist attack occurs,there is a long delay before evacuation,and most of the evacuees were in the state of“observation”before they moved.When one of the participants started to evacuate or shout,other participants would begin to recognize the danger and escape quickly.These three experiments showed that the route of the attacker had a significant impact on the routes and exit choices of the evacuees.Rather than searching for the nearest exit,the primary purpose of evacuees was to keep a safe distance from the attacker.The average speed of the evacuees in these three experiments was 1.07 m/s,0.81 m/s,and 0.84 m/s,respectively.The density distribution during the crowd evacuation process was uneven,with the highest density occurring at the area from the seats to the aisles.The research can provide data support for the design of emergency plans and the computer simulation of the armed assault attack.

Response of Escherichia coli to hydrogen nanobubbles:an in vitro evaluation using synchrotron infrared spectroscopy

Hydrogen(H2)-rich water,an apparent source of molecular H2,is an emerging functional drink with many purported benefits for human health(Yang et al.,2020;Ostojic,2021).The preventive and therapeutic effects of H2 on various pathological processes have been intensively investigated in numerous clinical trials;it is commonly believed that the beneficial effects are mainly attributed to its selective antioxidant and antiinflammatory properties(Lee et al.,2015;Ohta,2015;LeBaron et al.,2019;Qiu et al.,2020).In recent years,a handful of rodent studies revealed that exogenous H2 can afifect the gut microbiota(Sha et al.,2018;Valdes et al.,2018).