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1.
Article de Anglais | MEDLINE | ID: mdl-39312750

RÉSUMÉ

Developing monolithic materials for chromatography columns with a novel interconnected porous structure is vital for the enhancement of the separation efficiency of RNA purification processes. Herein, a porous nanofibrous sponge (PNFS) is constructed by freeze molding and freeze-drying a nanofiber dispersion with ethylene vinyl alcohol copolymer nanofibers as the skeleton, chitosan (CS) and polyethylenimine (PEI) as the binders, and glutaraldehyde (GA) as the crosslinking agent. The results show that when the CS content of the dispersion is 1.5 wt %, PNFS demonstrates a high static adsorption capacity of 406.5 mg/g (30.7 mg/m2) and a dynamic adsorption capacity of 382.6 mg/g (28.9 mg/m2) at a flow rate of 1 mm/min. Moreover, PNFS shows a high specific adsorption performance toward RNA in the presence of bovine serum albumin, lecithin, or DNA by adjusting the solution pH value and the method of gradient elution. Besides, PNFS presents exceptional performance in the rapid separation of RNA from HT22 cells without degradation. This result can be attributed to optimized morphology, pore structure, and comprehensive performance of PNFS, benefiting from the synergistic effect of the highly oriented porous structure and CS-PEI interaction derived from the high-density adsorption ligands on the channel walls of PNFS. This work provided an efficient strategy to handle the permeability/adsorptivity trade-off for ion-exchange chromatographic materials.

2.
J Clin Ultrasound ; 2024 Sep 12.
Article de Anglais | MEDLINE | ID: mdl-39264216

RÉSUMÉ

OBJECTIVE: To summarize the ultrasound diagnostic key points and imaging characteristics of absence of the internal carotid artery (ICA), and to explore the application value of carotid artery ultrasound in the diagnosis of ICA absence. METHODS: Sixteen patients diagnosed with ICA absence at our hospital were retrospectively analyzed. Clinical data, ultrasound images, and other relevant imaging data were reviewed. The ultrasound diagnostic key points and related imaging characteristics of ICA absence were summarized. Combined with a literature review, the application of carotid artery ultrasound in the diagnosis of ICA absence was discussed. RESULTS: Among the 16 patients, there were 10 males and 6 females ages ranging from 13 to 80 years. Among them, 5 patients had a history of cerebral infarction, 1 patient had a history of subarachnoid hemorrhage, and 10 patients had no history of stroke. Among the 16 patients, there were 10 left-sided lesions, 5 right-sided lesions, and 1 bilateral lesion. Three patients had concomitant aneurysms. Carotid ultrasound examinations in all 16 ICA absent patients revealed that a significantly slender common carotid artery (CCA) diameter compared to the contralateral (3.91 ± 0.73 vs. 6.92 ± 1.42, p < 0.001). On the side of ICA absence, the bifurcation of the carotid artery was not detected, with the CCA directly continuing as a single artery (external carotid artery, ECA). The temporal superficial artery percussion test was positive in all cases, and the blood flow spectrum of the single artery (ECA) on the side of the absent ICA showed a serrated pattern during diastole. On the side where the ICA was absent, the blood flow spectrum morphology of the CCA and ECA was consistent. Based on other relevant imaging examinations, the patients were classified into Lie types: A (10 cases), B (2 cases), C (1 case), D (1 case), and 2 cases were unclassified. CONCLUSION: Carotid artery ultrasound has the advantages of easy operation, affordability, non-invasiveness, and capable of dynamic and high repeatability. Compared to other imaging examinations, it can provide more evidence for the diagnosis of ICA absence, and is suitable for widespread application and promotion.

3.
Org Biomol Chem ; 2024 Sep 05.
Article de Anglais | MEDLINE | ID: mdl-39234762

RÉSUMÉ

A concise synthesis of aryl enol ethers from allylic alcohols and arylsulfonium salts by simply using an inorganic base as a mediator is described. The reaction enabled the facile conversion of various α-aryl allylic alcohols into the corresponding aryl enol ethers in good yields with excellent selectivity. The results demonstrated that both symmetric triarylsulfonium triflate and 10-methyl-5-aryl-5,10-dihydrophenothiazin-5-ium salts were effective arylation reagents for the base-initiated selective O-arylation and isomerization of α-aryl allylic alcohols. This reaction represents the first use of arylsulfonium salts as arylation reagents to access aryl enol ethers directly from allylic alcohols.

4.
Ageing Res Rev ; 100: 102443, 2024 Sep.
Article de Anglais | MEDLINE | ID: mdl-39097004

RÉSUMÉ

As a severe public health issue, depressive disorders (DD) has caused an increasingly burden of disease, especially in the older adults. To provide an overview and in-depth analysis of temporal trends in prevalence of DD in older adults at global, regional, and national levels over the last 30 years. Here, an age-period-cohort model was adopted to analyze age, period, and cohort effects. We showed that the global prevalence of DD in older adults was increasing. The net drift of the global prevalence of DD was showing an increasing trend in 78 countries, while local drift showing a declining trend in all age groups in high sociodemographic index (SDI) region. Additionally, period and cohort effects exhibited different patterns across regions. Over time, the declining trend was most significant in high SDI regions, while this trend was most significant in middle SDI region. Interestingly, those aged 60-64 years to 70-74 years was increasing globally, while age group aged 75-79 years to 95-99 years was on declining. In high, high-middle, and low SDI regions, individuals born early face higher risks than those born late, while the opposite results were observed in low-middle SDI region. Overall, our findings offer a insight global perspective for studying the temporal trends of DD prevalence, supplementing our evidence and understanding of DD epidemiology, and identifying gaps in DD prevention, management, and intervention plans in different aspects.


Sujet(s)
Trouble dépressif , Charge mondiale de morbidité , Santé mondiale , Humains , Sujet âgé , Prévalence , Trouble dépressif/épidémiologie , Charge mondiale de morbidité/tendances , Sujet âgé de 80 ans ou plus , Adulte d'âge moyen , Femelle , Mâle , Études de cohortes , Facteurs âges
5.
J Affect Disord ; 361: 367-375, 2024 Sep 15.
Article de Anglais | MEDLINE | ID: mdl-38897299

RÉSUMÉ

BACKGROUND: Depressive symptoms (DS) have become a global public health problem. However, a risk prediction model for DS in the elderly population has not been established. The purpose of this study was to develop and validate a predictive nomogram to screen for DS in the elderly population. METHODS: A cross-sectional data of 3396 participants aged 60 and over were obtained from the China Health and Retirement Longitudinal Study 2018 (CHARLS). Participants were divided into the development and validation set. Predictive factors were selected through a single-factor analysis, and then a predictive model nomogram was established. The discrimination, calibration, and clinical validity were evaluated using the receiver operating characteristic (ROC) curves, Hosmer-Lemeshow tests, and decision curve analyses (DCA). RESULTS: A total of 2379 and 1017 participants were included in the development and validation set, respectively. The analysis found that gender, residence, dyslipidemia, self-rated health, and ADL disability were risk factors for DS in older adults, and were included in the final model. This nomogram showed an acceptable predictive performance as evaluated by the area under the ROC curve with values of 0.684 (95 % confidence interval (CI): 0.663-0.706) and 0.687 (95 % CI: 0.655-0.719) in the development and validation set, respectively. The calibration curve indicated that the model was accurate, and DCA demonstrated a good clinical application value. CONCLUSION: Five factors were selected to establish a nomogram for predicting DS in older adults. The nomogram has a good evaluation performance and can be used as a reliable tool to predict DS among older adults.


Sujet(s)
Dépression , Nomogrammes , Humains , Mâle , Femelle , Sujet âgé , Chine/épidémiologie , Dépression/diagnostic , Dépression/épidémiologie , Adulte d'âge moyen , Études transversales , Facteurs de risque , Études longitudinales , Sujet âgé de 80 ans ou plus , Reproductibilité des résultats , Courbe ROC
6.
Polymers (Basel) ; 16(8)2024 Apr 16.
Article de Anglais | MEDLINE | ID: mdl-38675031

RÉSUMÉ

Lysozyme, a common antimicrobial agent, is widely used in the food, biopharmaceutical, chemical, and medicine fields. Rapid and effective isolation of lysozymes is an everlasting topic. In this work, ethylene vinyl alcohol (EVOH) copolymer nanofibrous membranes with a gradient porous structure used for lysozyme adsorption were prepared through layer-by-layer nanofiber wet-laying and a cost-efficient ultraviolet (UV)-assisted graft-modification method, where benzophenone was used as an initiator and 2-acrylamide-2-methylpropanesulfonic acid as a modifying monomer. As indicated in the Fourier Transform Infrared (FTIR) and X-ray photoelectric energy spectrometer (XPS) investigation, sulfonic acid groups were introduced on the surface of the modified nanofibrous membrane, which possessed the ability to adsorb lysozyme. Compared with membranes with homogenous porous structures, membranes with a gradient porous structure present higher static (335 mg/g) and dynamic adsorption capacities (216.3 mg/g). Meanwhile, the adsorption capacity remained high after five cycles of the adsorption-desorption process. The results can be attributed to the gradient porous structure rather than the highest porosity and specific surface area. This suggests that the membrane with comprehensive separation performance can be designed from the view of the transmembrane porous structure, which is of significance for the development of next-generation advanced chromatographic membranes.

7.
Org Lett ; 25(43): 7884-7889, 2023 Nov 03.
Article de Anglais | MEDLINE | ID: mdl-37877897

RÉSUMÉ

A visible-light-induced metal-free trifluoromethylselenolation of aryl iodides and bromides with [Me4N][SeCF3] is described. The reaction was conducted at ambient temperature by successfully harnessing the light-sensitive SeCF3 reagent. Mechanistically, the EDA complexes between aryl halide and the -SeCF3 anion or the base might be formed and excited by light, which subsequently undergo intracomplex SET processes to generate aryl and •SeCF3 radicals as key intermediates, allowing a convenient and green access to various aryl trifluoromethyl selenoethers.

8.
J Org Chem ; 88(13): 9372-9380, 2023 Jul 07.
Article de Anglais | MEDLINE | ID: mdl-37343224

RÉSUMÉ

Visible-light-induced decarboxylative trifluoromethylselenolation of (hetero)aromatic carboxylic acids with [Me4N][SeCF3], oxidant, and catalysts afforded a variety of (hetero)aryl trifluoromethyl selenoethers in good yields. The reaction might involve a radical process, which generated (hetero)aryl radicals from the stable (hetero)aromatic carboxylic acids via oxidative decarboxylation with NFSI as the oxidant, [di-tBu-Mes-Acr-Ph][BF4] as the photocatalyst, and 1,1'-biphenyl as the cocatalyst. Both catalysts had a decisive influence on the reaction. The trifluoromethylselenolation was further promoted by the copper salts probably via Cu-mediated cross-coupling of the sensitive SeCF3 species with the in situ formed (hetero)aryl radicals. Advantages of the method include visible light irradiation, mild reaction conditions at ambient temperature, good functional group tolerance, no pre-functionalization/activation of the starting carboxylic acids, and applicability to drug molecules. This protocol is promising and synthetically useful, which overcame the limitations of the known trifluoromethylselenolation methods and represented the first decarboxylative trifluoromethylselenolation of (hetero)aromatic carboxylic acids.


Sujet(s)
Acides carboxyliques , Cuivre , Cuivre/composition chimique , Décarboxylation , Acides carbocycliques , Acides carboxyliques/composition chimique , Oxydants
10.
Cell ; 186(9): 1985-2001.e19, 2023 04 27.
Article de Anglais | MEDLINE | ID: mdl-37075754

RÉSUMÉ

Aneuploidy, the presence of chromosome gains or losses, is a hallmark of cancer. Here, we describe KaryoCreate (karyotype CRISPR-engineered aneuploidy technology), a system that enables the generation of chromosome-specific aneuploidies by co-expression of an sgRNA targeting chromosome-specific CENPA-binding ɑ-satellite repeats together with dCas9 fused to mutant KNL1. We design unique and highly specific sgRNAs for 19 of the 24 chromosomes. Expression of these constructs leads to missegregation and induction of gains or losses of the targeted chromosome in cellular progeny, with an average efficiency of 8% for gains and 12% for losses (up to 20%) validated across 10 chromosomes. Using KaryoCreate in colon epithelial cells, we show that chromosome 18q loss, frequent in gastrointestinal cancers, promotes resistance to TGF-ß, likely due to synergistic hemizygous deletion of multiple genes. Altogether, we describe an innovative technology to create and study chromosome missegregation and aneuploidy in the context of cancer and beyond.


Sujet(s)
Centromère , Techniques génétiques , Humains , Aneuploïdie , Centromère/génétique , Délétion de segment de chromosome , Tumeurs/génétique , Clustered regularly interspaced short palindromic repeats
11.
Chem Rec ; 23(9): e202300071, 2023 Sep.
Article de Anglais | MEDLINE | ID: mdl-37098875

RÉSUMÉ

Carbamoyl fluorides, fluoroformates, and their analogues are a class of important compounds and have been evidenced as versatile building blocks for the preparation of useful molecules in organic chemistry. While major achievements were made in the synthesis of carbamoyl fluorides, fluoroformates, and their analogues in the last half of 20th century, an increasing number of reports have focused on using O/S/Se=CF2 species or their equivalents as the fluorocarbonylation reagents for the direct construction of these compounds from the parent heteroatom-nucleophiles in recent years. This review mainly summarizes the advances in the synthesis and typical application of carbamoyl fluorides, fluoroformates, and their analogues by the halide exchanges and fluorocarbonylation reactions since 1980.

12.
Org Biomol Chem ; 21(6): 1235-1241, 2023 Feb 08.
Article de Anglais | MEDLINE | ID: mdl-36633208

RÉSUMÉ

Preparation of alkyl fluorides and carbonates via divergent dehydroxyfluorination and carbonation of alcohols with trifluoromethyl trifluoromethanesulfonate (CF3SO2OCF3) is described. The reactions performed with BTMG in THF provided alkyl fluorides in good yields, whereas those of two different alcohols with Et3N in DCM formed asymmetric carbonates in moderate to excellent yields. CF3SO2OCF3 was demonstrated to be either a "F" or a "CO" reagent in the reactions by changing the base, allowing the selective construction of alkyl fluorides and carbonates from the corresponding alcohols with high efficiency. Notably, the fluorine-containing asymmetric carbonates that are difficult to synthesize by other methods were comprehensively prepared by this method, which would have great application potential in both academic and industrial fields.

13.
Article de Chinois | WPRIM (Pacifique Occidental) | ID: wpr-981746

RÉSUMÉ

OBJECTIVE@#To investigate the effect of different postures on direct anterior approach(DAA) total hip arthroplasty.@*METHODS@#Total of 94 patients who underwent DAA total hip arthroplasty from July 2016 to June 2020 were retrospectively analyzed. They were divided into two groups according to different positions during the operation, including 45 cases in lateral position and 49 cases in supine position (with the aid of stent). The general data such as gender, affected limb, body mass index(BMI), incision length, operation time, intraoperative bleeding volume, drainage volume 24 hours after operation, hemoglobin difference before and after operation, first landing time after operation, postoperative hospitalization time, postoperative complications, visual analogue scale(VAS) at 1 day, 1, 2 weeks, 1, 3 and 6 months after operation, Harris score at 1, 2 weeks, 1, 3 and 6 months after operation were observed and compared between the two groups.@*RESULTS@#Patients in both groups were followed up for 6 to 12 months with an average of (8.31±2.22) months. There was no significant difference between two groups in gender, affected limb, age, height, weight, body mass index(BMI), preoperative VAS score and preoperative Harris score(P>0.05). The incision length, operation time, intraoperative bleeding volume, 24-hour drainage volume, hemoglobin difference before and after operation, first time to the ground and postoperative hospitalization time of patients in supine position (assisted by stent) group were all better than those in lateral position group(P<0.05);There was no significant difference in the number of blood transfusions during and after operation(P=0.550). There was no significant difference in anteversion angle and abduction angle in the supine position(with the aid of stent) group during and after operation (P=0.825, P=0.066);There was significant difference in anteversion angle and abduction angle in the lateral position group during and after operation(P<0.05). VAS of patients in supine position (assisted by stent) group were lower than those in lateral position group at 1 day, 1, 2 weeks and 1 month after operation(P<0.05), and there was no statistical difference between two groups at 3 and 6 months after operation(P>0.05). Harris scores of patients in supine position(assisted by stent) group were higher than those in lateral position group at 1 week, 1 month and 3 months after operation(P<0.05), and there was no significant difference between two groups at 6 months after operation(P>0.05).@*CONCLUSION@#Compared with the lateral position, the supine position DAA total hip arthroplasty has the advantages of small incision, short operation time, less bleeding, early landing time, short hospitalization time, and small intraoperative acetabular cup position judgment error. It has the advantage of fast postoperative recovery, but the recovery of hip joint function is the same after 6 months.


Sujet(s)
Humains , Arthroplastie prothétique de hanche , Études rétrospectives , Antiviraux , Résultat thérapeutique , Posture
14.
iScience ; 25(12): 105566, 2022 Dec 22.
Article de Anglais | MEDLINE | ID: mdl-36465124

RÉSUMÉ

A copper-mediated trifluoromethyltelluration of arylboronic acids with [Me4N][TeCF3] using air as an environmental friendly oxidant is presented. The reaction proceeded smoothly under mild conditions in the presence of Cu(OTf)2 and bipyridine to provide the corresponding trifluoromethyltellurated products in good yields. Vinylboronic acid and arylboronic acid pinacol ester were also suitable substrates in the conversion but the yields are low. This transformation featured simplicity, good functional group tolerance, and a wide range of substrates, allowing for a convenient access to various TeCF3-containing molecules, and represented the first Chan-Lam type trifluoromethyltelluration with the highly reactive [Me4N][TeCF3] salt.

15.
Org Lett ; 24(45): 8417-8422, 2022 11 18.
Article de Anglais | MEDLINE | ID: mdl-36342364

RÉSUMÉ

Deuteration of arylthianthren-5-ium triflates with CD3OD or CD3OD/CD3COCD3 in the presence of Cs2CO3 by palladium catalysis or photoirradiation allowed the convenient synthesis of deuterated arenes in good yields. The Pd-catalyzed reaction generally gave better yields than the photoinduced deuteration, but exceptions also exist. They could complement each other in some cases. These reactions featured eco-friendly conditions, simplicity, inexpensive deuterium sources, good functional group tolerance, and a range of substrates. Since arylthianthren-5-ium salts could be readily synthesized from arenes and thianthrene 5-oxide, this protocol provided a formal aromatic C-H deuteration with high selectivity, enabling efficient deuterium labeling of multifunctionalized arenes and drug molecules.


Sujet(s)
Palladium , Sels , Deutérium/composition chimique , Catalyse , Palladium/composition chimique
16.
Elife ; 112022 09 21.
Article de Anglais | MEDLINE | ID: mdl-36129397

RÉSUMÉ

How cells control gene expression is a fundamental question. The relative contribution of protein-level and RNA-level regulation to this process remains unclear. Here, we perform a proteogenomic analysis of tumors and untransformed cells containing somatic copy number alterations (SCNAs). By revealing how cells regulate RNA and protein abundances of genes with SCNAs, we provide insights into the rules of gene regulation. Protein complex genes have a strong protein-level regulation while non-complex genes have a strong RNA-level regulation. Notable exceptions are plasma membrane protein complex genes, which show a weak protein-level regulation and a stronger RNA-level regulation. Strikingly, we find a strong negative association between the degree of RNA-level and protein-level regulation across genes and cellular pathways. Moreover, genes participating in the same pathway show a similar degree of RNA- and protein-level regulation. Pathways including translation, splicing, RNA processing, and mitochondrial function show a stronger protein-level regulation while cell adhesion and migration pathways show a stronger RNA-level regulation. These results suggest that the evolution of gene regulation is shaped by functional constraints and that many cellular pathways tend to evolve one predominant mechanism of gene regulation at the protein level or at the RNA level.


Sujet(s)
Tumeurs , Protéogénomique , Aneuploïdie , Humains , Protéines membranaires , Tumeurs/génétique , ARN
17.
Chem Commun (Camb) ; 58(66): 9238-9241, 2022 Aug 16.
Article de Anglais | MEDLINE | ID: mdl-35899839

RÉSUMÉ

Trifluoromethylselenolation of arenes with [Me4N][SeCF3] in the presence of an oxidant through Pd-catalyzed C(sp2)-H activation under the assistance of a directing group is established for the first time. The reaction tolerates different directing groups and a variety of functional groups, enabling selective installation of a SeCF3 moiety onto the ortho positions of arenes. Mechanistic studies revealed that the CF3SeSeCF3 intermediate in situ generated from oxidation of [Me4N][SeCF3] might be the real SeCF3 reagent in the reaction.

18.
Curr Med Sci ; 42(3): 561-568, 2022 Jun.
Article de Anglais | MEDLINE | ID: mdl-35678917

RÉSUMÉ

OBJECTIVE: To evaluate the impact of hypertension on the clinical outcome of COVID-19 patients aged 60 years old and older. METHODS: This single-center retrospective cohort study enrolled consecutive COVID-19 patients aged 60 years old and older, who were admitted to Liyuan Hospital from January 1, 2020 to April 25, 2020. All included patients were divided into two groups: hypertension and nonhypertension group. The baseline demographic characteristics, laboratory test results, chest computed tomography (CT) images and clinical outcomes were collected and analyzed. The prognostic value of hypertension was determined using binary logistic regression. RESULTS: Among the 232 patients included in the analysis, 105 (45.3%) patients had comorbid hypertension. Compared to the nonhypertension group, patients in the hypertension group had higher neutrophil-to-lymphocyte ratios, red cell distribution widths, lactate dehydrogenase, high-sensitivity C-reactive protein, D-dimer and severity of lung lesion, and lower lymphocyte counts (all P<0.05). Furthermore, the hypertension group had a higher proportion of intensive care unit admissions [24 (22.9%) vs. 14 (11.0%), P=0.02) and deaths [16 (15.2%) vs. 3 (2.4%), P<0.001] and a significantly lower probability of survival (P<0.001) than the nonhypertension group. Hypertension (OR: 4.540, 95% CI: 1.203-17.129, P=0.026) was independently correlated with all-cause in-hospital death in elderly patients with COVID-19. CONCLUSION: The elderly COVID-19 patients with hypertension tend to have worse conditions at baseline than those without hypertension. Hypertension may be an independent prognostic factor of poor clinical outcome in elderly COVID-19 patients.


Sujet(s)
COVID-19 , Hypertension artérielle , Sujet âgé , COVID-19/complications , Mortalité hospitalière , Humains , Hypertension artérielle/complications , Hypertension artérielle/épidémiologie , Adulte d'âge moyen , Études rétrospectives , SARS-CoV-2
19.
Soft Matter ; 18(26): 4991-5000, 2022 Jul 06.
Article de Anglais | MEDLINE | ID: mdl-35758290

RÉSUMÉ

Constructing a sterile membrane with a robust and antifouling surface is a powerful means to improve the sterile filtration efficiency of sterile membranes. In this work, a robust EVOH nanofibrous sterile membrane was facilely fabricated by the method of in situ crosslinking with glutaraldehyde and surface plasma treatment. The resultant EVOH nanofibrous sterile membrane possessed a carboxylated-crosslinked surface, with high hydrophilicity, which generated high chemical stability, high-temperature steam resistance, and an ultrahigh antifouling performance against bovine serum albumin, ribonucleic acid and nanoparticle pollutants. Moreover, the membrane also exhibited a reasonably high primary water permeance (4522.2 LMH bar-1 at 0.2 MPa), as well as an absolute interception rate (100%) of Escherichia coli, Staphylococcus aureus cells and Brevundimonas diminuta superior to the state-of-the-art sterile membrane. Moreover, the modified membrane packed syringe-driven filter presented 100% interception (LRV ≥ 7) to Brevundimonas diminuta and high permeation flux (from 10.8 to 41.8 L·h-1) in a wide operating pressure range of 0.1 MPa to 0.6 MPa, indicating its potential in real bio-separation applications. This work provides a facile strategy for the preparation of a high-performance sterile membrane for biological drug product sterilization.


Sujet(s)
Encrassement biologique , Nanofibres , Encrassement biologique/prévention et contrôle , Caulobacteraceae , Escherichia coli , Glutaraldéhyde , Membrane artificielle
20.
Build Environ ; 219: 109166, 2022 Jul 01.
Article de Anglais | MEDLINE | ID: mdl-35574565

RÉSUMÉ

Leading health authorities have suggested short-range airborne transmission as a major route of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). However, there is no simple method to assess the short-range airborne infection risk or identify its governing parameters. We proposed a short-range airborne infection risk assessment model based on the continuum model and two-stage jet model. The effects of ventilation, physical distance and activity intensity on the short-range airborne exposure were studied systematically. The results suggested that increasing physical distance and ventilation reduced short-range airborne exposure and infection risk. However, a diminishing return phenomenon was observed when the ventilation rate or physical distance was beyond a certain threshold. When the infectious quantum concentration was less than 1 quantum/L at the mouth, our newly defined threshold distance and threshold ventilation rate were independent of quantum concentration. We estimated threshold distances of 0.59, 1.1, 1.7 and 2.6 m for sedentary/passive, light, moderate and intense activities, respectively. At these distances, the threshold ventilation was estimated to be 8, 20, 43, and 83 L/s per person, respectively. The findings show that both physical distancing and adequate ventilation are essential for minimising infection risk, especially in high-intensity activity or densely populated spaces.

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