Surgical masks have been worn by the public worldwide during the COVID-19 pandemic, yet hazardous chemicals in the petroleum-derived polymer layer of masks are currently ignored and unregulated. These organic compounds pose potential health risks to the mask wearer through dermal contact or inhalation. Here, we show that surgical masks from around the world are loaded with semivolatile and volatile organic compounds (VOCs), including alkanes, polycyclic aromatic hydrocarbons (PAHs), phthalate esters, and reactive carbonyls at ng to μg/mask levels. Naphthalene was the most abundant mask-borne PAH, accounting for over 80% of total PAH levels; acrolein, a mutagenic carbonyl, was detected in most of the mask samples, and di(2ethylhexyl) phthalate, an androgen antagonist, was detected in one-third of the samples. Furthermore, there is large mask-to-mask variability of the residue VOCs, revealing the uneven quality of masks. We confirm that masks containing more residue VOCs lead to significantly higher exposure levels and associated disease risks to the wearer, which should warrant the attention of the general public and regulatory agencies. We find that heating the masks at 50 °C for as short as 60 min lowers the total VOC content by up to 80%, providing a simple method to limit our exposure to maskborne VOCs.
Chronic exposure to aristolochic acids (AAs) from Aristolochia plants is one of the major causes of nephropathy and cancer of the kidney and forestomach. However, the organotropic activities of AAs remain poorly understood. In this study, using LC−MS/MS coupled with a stable isotope-dilution method, we rigorously quantitated for the first time the organ-specific dosage-and time-dependent formation of DNA-AA adducts in the tumor target and nontarget organs of AA-I-treated rats. The results support the proposal that the DNA adduct level is a major contributor to the observed organotropic activities of AAs.
In
this study, we assessed the feasibility of using ordinary face
masks as a sampling means to collect airborne polycyclic aromatic
hydrocarbons (PAHs). Nonwoven fabric masks can trap three-ring or
larger PAHs at a high efficiency (>70%) and naphthalene at ∼17%.
The sampling method is quantitative as confirmed by comparison with
the standard method of the National Institute for Occupational Safety
and Health. In conjunction with sensitive fluorescence detection,
the method was applied to quantify nine airborne PAHs in a range of
indoor and outdoor environments. Wearing the mask for 2 h allowed
quantification of individual PAHs as low as 0.07 ng/m3.
The demonstration shows applicability of the method in monitoring
PAHs down to ∼30–80 ng/m3 in university office
and laboratory settings and up to ∼900 ng/m3 in
an incense-burning temple. Compared with traditional filter-/sorbent
tube-based approaches, which require a sampling pump, our new method
is simple, convenient, and inexpensive. More importantly, it closely
tracks human exposure down to the individual level, thus having great
potential to facilitate routine occupational exposure monitoring and
large-scale surveillance of PAH concentrations in indoor and outdoor
environments.
Emerging
evidence suggests that cross-links formed by reacting
DNA lesions with proteins may play a significant role in the pathophysiology
of human cancer and degenerative diseases. The goal of this study
was to develop a method involving liquid chromatography-tandem mass
spectrometry (LC–MS/MS) coupled with the stable isotope-dilution
method to quantify DNA–protein cross-link (DPC). A novel type
of cross-link involving a S-glycosidic linkage formed
by reacting an abasic site in DNA with the cysteine residues in protein
was targeted in this study. The method entails hydrolysis of the cross-link
to a 2′-deoxyribose-cysteine adduct, addition of isotopically
labeled internal standard, and quantitation by LC–MS/MS analysis.
The accuracy and precision of the method were evaluated with a synthetic
peptide containing the cross-link. The validated method was then applied
to quantitate the levels of the DNA–protein cross-link in vitro and in HeLa cells exposed to alkylating agent methylmethanesulfonate
(MMS). The analysis detected dosage-dependent formation of the cross-link
in both purified DNA (6.0 ± 0.6 DPC per 106 nt μM–1 MMS) and in human cells (7.8 ± 1.2 DPC per 106 nt mM–1 MMS). With the abasic site being
one of the most common DNA lesions produced continuously by multiple
pathways, the results provide significant new knowledge for better
understanding the potential biological implications of its associated
DNA–protein cross-link.
Abstract:To solve the problem, because of which conventional quick-charging strategies (CQCS) cannot meet the requirements of quick-charging for multiple types of electric vehicles (EV) on highways where vehicle inflow is excessive, this paper proposed a new quick-charging strategy (NQCS) for EVs: on the premise of not affecting those EVs being charged, the remaining power of the quick-charging pile with multiple power output interfaces is used to provide a synchronous charging service for EVs waiting in the queue. To verify the effectiveness of this strategy, a power distribution model of charging pile and a queuing model of charging station (CS) were constructed. In addition, based on an actual highway service area where vehicle inflow is excessive during the simulation period (0:00-24:00), charging situations of CQCS and NQCS were respectively simulated in a charging station (CS), with different number of chargers, by basic queuing algorithm and an improved queuing algorithm. The simulation results showed that when the relative EV inflow is excessive, compared to CQCS, NQCS not only can reduce user waiting time, charging time, and stay time, but also can improve the utilisation rate of charging infrastructure and service capacity of CS and reduce the queue length of CS. At the same time, NQCS can reduce the impact on the power grid. In addition, in NQCS, the on-demand power distribution method is more efficient than the average power distribution method. Therefore, NQCS is more suitable for quick-charging for multiple types of EVs on highways where vehicle inflow is excessive.
Abstract:With the large-scale adoption of electric vehicles (EVs) on expressways, the exploration of a guiding-based charging method to effectively adjust interactions between EVs and the fast charging stations (CSs) is urgently needed. This paper proposes a status-of-use (SOU) price-based charging strategy that can motivate users to charge in advance. A queuing model for a CS cluster was established to verify the effectiveness of the strategy, and then a simulation of traveling and charging conditions of 12,000 pure EVs on the road network from 0:00 to 24:00 was performed according to the related data and using the Monte Carlo method, the Floyd-Warshall algorithm, and the queuing algorithm proposed in this paper. Compared to unordered charging (UC), SOU price-based charging can not only reduce the charging cost and waiting time for users, but also increase the utilization ratio of charging facilities in a CS cluster and thus lower their influence on the power grid and expressway traffic. SOU price-based charging can effectively adjust interactions between EVs and CSs.
Accumulating evidence suggests that DNA lesioninduced DNA−protein cross-links (DPCs) interrupt normal DNA metabolic processes, such as transcription, replication, and repair, resulting in profound biological consequences, including the development of many human diseases, such as cancers. Although apurinic/apyrimidinic (AP) sites are among the most predominant DNA lesions and are in close proximity to the histone proteins that they wrap around in the nucleosome, knowledge of the chemical structure or biological consequences of their associated DPCs is limited in part due to a lack of sensitive and selective analytical methods. We developed liquid chromatography−tandem mass spectrometry coupled with a stable isotope dilution method for rigorous quantitation of DPCs formed by reacting a DNA AP site with a lysine residue. In combination with chemical derivatization with fluorenylmethoxycarbonyl chloride to form a hydrophobic conjugate, the developed LC−MS/MS method allows sensitive detection of AP site-Lys cross-links down to sub-1 adduct per 10 6 nt. After validation using a synthetic AP site-lysine-cross-linked peptide and an oligodeoxyribonucleotide, the method was used to determine the concentration of AP site-lysine cross-links in hot acid-treated DNA and in human cells exposed to methyl methanesulfonate.
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