Effects of a closed-loop system against SARS-CoV-2 at the Beijing 2022 Olympic Winter Games:a descriptive and modeling study

BACKGROUND:To assess the efficacy of the epidemic prevention measures of the“closed-loop”system adopted by the Beijing 2022 Olympic Winter Games(BOWG).METHODS:We retrospectively collected and analyzed information,including age,sex,nationality,vaccination status,date of diagnosis,and date of entry,from 280 SARS-CoV-2-positive individuals identified during the BOWG.A susceptibility-exposed-infectious-remove model was employed to evaluate the effectiveness of epidemic prevention strategies on controlling the spread of SARS-CoV-2 under different scenarios during the BOWG.RESULTS:Regarding SARS-CoV-2-positive cases,97.9%were imported,and 96.4%were asymptomatic.The median age was 37 years(range:29–47 years),and 73.9%were male,with the majority of cases being broadcasters and European attendees.Regarding vaccination status,93.5%were fully vaccinated,and six cases were considered to have been infected in the closed-loop system during the BOWG.Assuming that the BOWG adopted a semi-closed-loop management system,the cumulative number of confirmed cases would be 1,137 for quick quarantine measures(3 d later)implemented and 5,530 for delayed quarantine measures(9 d later)implemented.This modeling revealed that stringent pandemic prevention measures and closed-loop management effectively controlled the spread of SARS-CoV-2 during the BOWG.CONCLUSION:Imported cases are considered the main risk factor for SARS-CoV-2 transmission during mass gatherings,but a comprehensive closed-loop system could minimize transmission among attendees and general personnel.

Risk management strategies for the 2022 Olympic Winter Games:The Beijing scheme

As the first international sporting event scheduled since the outbreak of the novel coronavirus disease 2019(COVID-19)pandemic,the Beijing XXIV Olympic Winter Games were officially held in China between the 4th and 20th of February 2022.1 According to the International Olympic Committee(IOC),there were approximately 2900 elite athletes from 91 National Olympic Committees competing in 109 events during the 16 days of the Games.2 In fact,under the conditions of a global pandemic,mass gatherings during large-scale sporting events represent a conducive environment for viral transmission given the close,prolonged,and frequent interactions between participants;this includes an increased risk of transmission of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).

Mesocrystalline TiO2/sepiolite composites for the effective degradation of methyl orange and methylene blue

Mesocrystalline TiO2/sepiolite （TiS） composites with the function of adsorption and degradation of liquid organic pollutants were successfully fabricated via a facile and low-cost solvothermal reaction. The prepared TiS composites were characterized by FESEM, HRTEM, XRD, XPS, N2 adsorption-desorption, UV-vis DRS, and EPR. Results revealed the homogeneous dispersion of highly reactive TiO2 mesocrystals on the sepiolite nanofibers. Thereinto each single-crystal-like TiO2 mesocrystal comprised many [001]-oriented anatase nanoparticles about 10-20 nm in diameter. The photocatalytic activity was further evaluated by the degradation of anionic dye （methyl orange） and cationic dye （methylene blue） under the UV-vis light （350≤λ≤780 nm） irradiation. By selecting appropriate experimental conditions, we can easily manipulate the photocatalytic performance of TiS composites. The optimal TiS catalyst （the sepiolite content of 28.5 wt.%, and the reaction time of 24 h） could efficiently degrade methyl orange to 90.7% after 70 min, or methylene blue to 97.8% after 50 min, under UV-vis light irradiation. These results can be attributed to their synergistic effect of high crystallinity, large specific surface area, abundant hydroxyl radicals, and effective photogenerated charge separation.

Attractive nanofiber structure based on Cu-Ti/metal sandwich film with excellent electrocatalytic performance for ethanol oxidation

The support materials are an important part of catalysts and they are the dispersant,adhesive,and support for other components.In this study,three types of thin films with different structures were used as the precursor to prepare loading Pd catalysts.The one-step dealloying method was used to prepare a semiconductor nanofiber film(NFF)support material with upward directional growth from the substrate.Pd/NFF and Pd/Ni O/NFF loaded Pd catalysts were prepared using NFF as the support material,and the electrochemical catalytic properties for ethanol oxidation in alkaline media were studied.Cyclic votammetry showed that the NFF support material effectively inhibited agglomeration of palladium,increased the number of active sites of Pd,and improved the electrocatalytic properties of Pd for ethanol oxidation.In addition,the Pd/Ni O/NFF loaded Pd catalyst obtained by modification with nickel oxide significantly improved the electrocatalytic performance for ethanol oxidation compared with the Pd/NFF loaded Pd catalyst.These results show that Ni O is conductive to absorption of oxygen-containing groups on the surface of the catalyst and can further improve the electrocatalytic ability of Pd for ethanol oxidation.All of the above results demonstrate that the support material prepared by the dealloying method has application prospects in load-type catalysts.

Cardiopulmonary resuscitation and termination of resuscitation on out-of-hospital cardiac arrest in China

To the Editor: Out-of-hospital cardiac arrest (OHCA) is a major public health challenge. Early initiation, good quality cardiopulmonary resuscitation (CPR), and the use of an automated external defibrillator (AED) have been reported to significantly improve the survival and long-term outcomes in survivors of OHCA.

What is an effective cardiopulmonary resuscitation training mode?

To the Editor:Out-of-hospital cardiac arrest(OHCA)is a serious threat to people's lives and safety.The annual incidence of OHCA in North America is approximately 55/100,000,and it is approximately 59/100,000 in Asia.[1,2]How can the success rate of resuscitation be improved in patients with cardiac arrest?The American Heart Association(AHA)and the European Resuscitation Council have put forward their own cardiopulmonary resuscitation(CPR)guidelines,which are constantly updated with the latest research evidence.CPR training is also an important part of the guidelines.[3,4]Chinese colleagues also try to improve the success rate of rescuing patients with cardiac arrest based on the experience of their international counterparts and combine it with Chinese characteristics.CPR training is in full swing,which includes the training of first responders and medical staff.

Association between duration of return of spontaneous circulation and outcomes after out-of-hospital cardiac arrest

Background:Return of spontaneous circulation(ROSC)is a core outcome element of cardiopulmonary resuscitation(CPR);however,the definition or criterion of ROSC is disputed and varies in resuscitation for out-of-hospital cardiac arrest(OHCA).Methods:This was a retrospective study of 126 patients with OHCA who achieved ROSC between January and December 2020.The probability of survival after OHCA related to CPR and ROSC duration was analyzed using the probability density function and empirical cumulative density functions.Results:There were no significant differences between ROSC sustained until emergency department arrival and that sustained for at least 20 minutes in terms of the 24-hour survival rate(31.3%[31/99]vs.35.7%[10/30];P=0.84),30-day survival rate(23.2%[23/99]vs.25.0%[7/30];P=0.99),or survival at 30 days with cerebral performance category(CPC)1 and 2(18.2%[18/99]vs.10.7%[3/30];P=0.44).The Kolmogorov-Smirnov test values from the empirical cumulative density functions with ROSC sustained until hospital arrival and that sustained for at least 20 minutes were 0.44,0.20,and 0.24 for CPC 1 or 2,CPC 3 or 4,and CPC 5,respectively.Conclusion:Return of spontaneous circulation is a core outcome element of CPR.It should be defined as sustained for at least 20 minutes or until arrival at the emergency department and as a basic standard for evaluating resuscitation success after OHCA.