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Chunlin Li

Other affiliations: University of Lyon, Fudan University
Bio: Chunlin Li is an academic researcher from Weizmann Institute of Science. The author has contributed to research in topics: Medicine & Chemistry. The author has an hindex of 12, co-authored 28 publications receiving 991 citations. Previous affiliations of Chunlin Li include University of Lyon & Fudan University.

Papers
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Journal ArticleDOI
TL;DR: The aim of this work was to comprehensively review most of the studies published on this topic in China, including literature concerning field measurements, laboratory studies and the impacts of BB indoors and outdoors in China to provide a basis for formulation of policies and regulations by policy makers in China.

772 citations

Journal ArticleDOI
TL;DR: It is shown that the high-affinity variant RBD-62 can be used as a drug to inhibit infection with SARS-CoV-2 and variants Alpha, Beta and Gamma in vitro and its structure provides a structural basis for future drug and vaccine development and for in silico evaluation of known antibodies.
Abstract: SARS-CoV-2 variants of interest and concern will continue to emerge for the duration of the COVID-19 pandemic. To map mutations in the receptor-binding domain (RBD) of the spike protein that affect binding to angiotensin-converting enzyme 2 (ACE2), the receptor for SARS-CoV-2, we applied in vitro evolution to affinity-mature the RBD. Multiple rounds of random mutagenic libraries of the RBD were sorted against decreasing concentrations of ACE2, resulting in the selection of higher affinity RBD binders. We found that mutations present in more transmissible viruses (S477N, E484K and N501Y) were preferentially selected in our high-throughput screen. Evolved RBD mutants include prominently the amino acid substitutions found in the RBDs of B.1.620, B.1.1.7 (Alpha), B1.351 (Beta) and P.1 (Gamma) variants. Moreover, the incidence of RBD mutations in the population as presented in the GISAID database (April 2021) is positively correlated with increased binding affinity to ACE2. Further in vitro evolution increased binding by 1,000-fold and identified mutations that may be more infectious if they evolve in the circulating viral population, for example, Q498R is epistatic to N501Y. We show that our high-affinity variant RBD-62 can be used as a drug to inhibit infection with SARS-CoV-2 and variants Alpha, Beta and Gamma in vitro. In a model of SARS-CoV-2 challenge in hamster, RBD-62 significantly reduced clinical disease when administered before or after infection. A 2.9 A cryo-electron microscopy structure of the high-affinity complex of RBD-62 and ACE2, including all rapidly spreading mutations, provides a structural basis for future drug and vaccine development and for in silico evaluation of known antibodies.

253 citations

Journal ArticleDOI
TL;DR: In this article, the authors conducted simulation experiments to characterize emission factors of PM 2.5 emitted from agricultural crop residue burning in China, including open field burning and burned as household fuel.

103 citations

Journal ArticleDOI
TL;DR: The optical properties of BrC change due to transformations driven by reactions with the NO3 radical that form new absorbing species and lead to significant absorption enhancement over the UV-visible range.
Abstract: Atmospheric brown carbon (BrC) is an important contributor to the radiative forcing of climate by organic aerosols. Because of the molecular diversity of BrC compounds and their dynamic transformations, it is challenging to predictively understand BrC optical properties. OH radical and O3 reactions, together with photolysis, lead to diminished light absorption and lower warming effects of biomass burning BrC. The effects of night-time aging on the optical properties of BrC aerosols are less known. To address this knowledge gap, night-time NO3 radical chemistry with tar aerosols from wood pyrolysis was investigated in a flow reactor. This study shows that the optical properties of BrC change because of transformations driven by reactions with the NO3 radical that form new absorbing species and lead to significant absorption enhancement over the ultraviolet-visible (UV-vis) range. The overnight aging increases the mass absorption coefficients of the BrC by a factor of 1.3-3.2 between 380 nm and 650 nm. Nitrated organic compounds, particularly nitroaromatics, were identified as the main products that contribute to the enhanced light absorption in the secondary BrC. Night-time aging of BrC aerosols represents an important source of secondary BrC and can have a pronounced effect on atmospheric chemistry and air pollution.

84 citations

Journal ArticleDOI
TL;DR: In this article, a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and single-particle laser desorption/resonance (SPL) was used for the analysis of fresh and aged tar balls.
Abstract: Following wood pyrolysis, tar ball aerosols were laboratory generated from wood tar separated into polar and nonpolar phases Chemical information of fresh tar balls was obtained from a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and single-particle laser desorption/resonance enhanced multiphoton ionization mass spectrometry (SP-LD-REMPI-MS) Their continuous refractive index (RI) between 365 and 425 nm was retrieved using a broadband cavity enhanced spectroscopy (BBCES) Dynamic changes in the optical and chemical properties for the nonpolar tar ball aerosols in NOx -dependent photochemical process were investigated in an oxidation flow reactor (OFR) Distinct differences in the chemical composition of the fresh polar and nonpolar tar aerosols were identified Nonpolar tar aerosols contain predominantly high-molecular weight unsubstituted and alkyl-substituted polycylic aromatic hydrocarbons (PAHs), while polar tar aerosols consist of a high number of oxidized aromatic substances (eg, methoxy-phenols, benzenediol) with higher O : C ratios and carbon oxidation states Fresh tar balls have light absorption characteristics similar to atmospheric brown carbon (BrC) aerosol with higher absorption efficiency towards the UV wavelengths The average retrieved RI is 1661+0020i and 1635+0003i for the nonpolar and polar tar aerosols, respectively, with an absorption Angstrom exponent (AAE) between 57 and 78 in the detected wavelength range The RI fits a volume mixing rule for internally mixed nonpolar/polar tar balls The RI of the tar ball aerosols decreased with increasing wavelength under photochemical oxidation Photolysis by UV light (254 nm), without strong oxidants in the system, slightly decreased the RI and increased the oxidation state of the tar balls Oxidation under varying OH exposure levels and in the absence of NOx diminished the absorption (bleaching) and increased the O : C ratio of the tar balls The photobleaching via OH radical initiated oxidation is mainly attributed to decomposition of chromophoric aromatics, nitrogen-containing organics, and high-molecular weight components in the aged particles Photolysis of nitrous oxide ( N2O ) was used to simulate NOx -dependent photochemical aging of tar balls in the OFR Under high- NOx conditions with similar OH exposure, photochemical aging led to the formation of organic nitrates, and increased both oxidation degree and light absorption for the aged tar ball aerosols These observations suggest that secondary organic nitrate formation counteracts the bleaching by OH radical photooxidation to eventually regain some absorption of the aged tar ball aerosols The atmospheric implication and climate effects from tar balls upon various oxidation processes are briefly discussed

78 citations


Cited by
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01 Dec 2006
TL;DR: This paper showed that reactive anthropogenic VOCs (AVOCs) produce much larger amounts of SOA than these models predict, even shortly after sunrise, and a significant fraction of the excess SOA is formed from first-generation AVOC oxidation products.
Abstract: [1] The atmospheric chemistry of volatile organic compounds (VOCs) in urban areas results in the formation of ‘photochemical smog’, including secondary organic aerosol (SOA). State-of-the-art SOA models parameterize the results of simulation chamber experiments that bracket the conditions found in the polluted urban atmosphere. Here we show that in the real urban atmosphere reactive anthropogenic VOCs (AVOCs) produce much larger amounts of SOA than these models predict, even shortly after sunrise. Contrary to current belief, a significant fraction of the excess SOA is formed from first-generation AVOC oxidation products. Global models deem AVOCs a very minor contributor to SOA compared to biogenic VOCs (BVOCs). If our results are extrapolated to other urban areas, AVOCs could be responsible for additional 3–25 Tg yr−1 SOA production globally, and cause up to −0.1 W m−2 additional top-of-the-atmosphere radiative cooling.

947 citations

Journal ArticleDOI
TL;DR: The aim of this work was to comprehensively review most of the studies published on this topic in China, including literature concerning field measurements, laboratory studies and the impacts of BB indoors and outdoors in China to provide a basis for formulation of policies and regulations by policy makers in China.

772 citations

Journal ArticleDOI
01 Jan 2022-Cell
TL;DR: In this article , a new SARS-CoV-2 viral isolate Omicron-B.1.529 was announced, containing far more mutations in Spike (S) than previously reported variants, leading to a large number of mutations in the ACE2 binding site and rebalances receptor affinity to that of earlier pandemic viruses.

714 citations

Journal ArticleDOI
01 Jun 2019
TL;DR: In this paper, the authors reviewed different sources of biomass available, along with their chemical composition and properties, and discussed different conversion technologies (i.e., thermo-chemical, biochemical, and physico-chemical conversions) and their corresponding products.
Abstract: Biomass is currently the most widespread form of renewable energy and its exploitation is further increasing due to the concerns over the devastative impacts of fossil fuel consumption, i.e., climate change, global warming and their negative impacts on human health. In line with that, the present articles reviews the different sources of biomass available, along with their chemical composition and properties. Subsequently, different conversion technologies (i.e., thermo-chemical, biochemical, and physico-chemical conversions) and their corresponding products are reviewed and discussed. In the continuation, the global status of biomass vs. the other renewable energies is scrutinized. Moreover, biomass-derived energy production was analyzed from economic and environmental perspectives. Finally, the challenges faced to further expand the share of biomass-derived energy carriers in the global energy market are presented.

461 citations