Imaging of pH distribution inside individual microdroplet by stimulated Raman microscopy.

Aerosol microdroplets as microreactors for many important atmospheric reactions are ubiquitous in the atmosphere. pH largely regulates the chemical processes within them; however, how pH and chemical species spatially distribute within an atmospheric microdroplet is still under intense debate. The challenge is to measure pH distribution within a tiny volume without affecting the chemical species distribution. We demonstrate a method based on stimulated Raman scattering microscopy to visualize the three-dimensional pH distribution inside single microdroplets of varying sizes. We find that the surface of all microdroplets is more acidic, and a monotonic trend of pH decreasing is observed in the 2.9-µm aerosol microdroplet from center to edge, which is well supported by molecular dynamics simulation. However, bigger cloud microdroplet differs from small aerosol for pH distribution. This size-dependent pH distribution in microdroplets can be related to the surface-to-volume ratio. This work presents noncontact measurement and chemical imaging of pH distribution in microdroplets, filling the gap in our understanding of spatial pH in atmospheric aerosol.

Performance of nonalcoholic fatty liver fibrosis score in estimating atherosclerotic cardiovascular disease risk.

BACKGROUND AND AIMS: It is currently unclear whether the nonalcoholic fatty liver disease (NAFLD) fibrosis score, when compared to major anthropometric indices, is useful in estimating the risk of atherosclerotic cardiovascular disease (ASCVD). METHODS AND RESULTS: This study included 3886 adults undergoing a health checkup. An elevated risk of ASCVD was determined as a 10-year ASCVD risk ≥7.5% using Pooled Cohort Equations. NAFLD was diagnosed with abdominal ultrasonography. Receiver operating characteristic curves were used to evaluate the performance of estimating an elevated ASCVD risk. Among study participants, 521 (13.4%) had an elevated ASCVD risk and 1473 (37.9%) had NAFLD. Subjects with NAFLD had a significantly higher rate of ASCVD risk ≥7.5% (p < 0.001) compared to those without NAFLD. After adjusting for cardiometabolic risk factors, NAFLD (OR = 1.49, 95% CI: 1.10-2.00, p = 0.009) in all participants and NAFLD fibrosis score >0.676 (OR = 1.95, 95% CI: 1.30-2.92, p = 0.001) in individuals with NAFLD were significantly associated with an elevated risk of ASCVD. When compared to different anthropometric indices, NAFLD fibrosis score exhibited the largest area under the curve (AUC) in individuals with NAFLD (AUC = 0.750) in estimating an elevated ASCVD risk. Furthermore, NAFLD fibrosis score displayed the best predictive performance for identifying an elevated ASCVD risk in male participants with NAFLD (AUC = 0.737). CONCLUSION: NAFLD was a significant risk factor for elevated ASCVD risk. NAFLD fibrosis score >0.676 was associated with increased ASCVD risk in individuals with NAFLD. Compared with anthropometric indices, NAFLD fibrosis score demonstrated the best performance in estimating elevated ASCVD risk among those with NAFLD.

What is the association between secondhand smoke (SHS) and possible obstructive sleep apnea: a meta-analysis.

BACKGROUND: Association between smoking and sleep apnea is well-known from previous studies. However, the influence of secondhand smoke (SHS), which is a potential risk factor of obstructive sleep apnea (OSA), remains unclear. Our aim was to investigate the relationship between SHS and OSA using a meta-analysis. MATERIALS AND METHODS: For the meta-analysis, searches were performed in MEDLINE, EMBASE, and Web of Science databases on January 10, 2022, by combining various keywords including "SHS exposure" and "OSA". Data were extracted using defined inclusion and exclusion criteria. Fixed-effects model meta-analyses were used to pool risk ratio (RR) estimates with their 95% confidence intervals (CI). I2 was used to assess heterogeneity. Moreover, we performed subgroup meta-analyses of children-adults, and smoker fathers and mothers. RESULTS: In total, 267 articles were obtained through an electronic search. Twenty-six articles were included in our analysis according to the inclusion and exclusion criteria. We found evidence of an association between SHS exposure and possible OSA (RR 1.64, 95% CI 1.44-1.88). The results of the subgroup analyses showed that children passive smokers (RR 1.84, 95% CI 1.60-2.13) were at greater risks of possible OSA than adult passive smokers (RR 1.35, 95% CI 1.21-1.50). Also, significant differences were observed in mothers with smoking exposure (RR 2.61, 95% CI 1.62-4.21, p < 0.0001), as well as in fathers with smoking exposure (RR 2.15, 95% CI 0.98-4.72, p = 0.06). SHORT CONCLUSION: Our meta-analysis confirmed that SHS exposure is significantly associated with OSA. In the subgroup analyses, the association of SHS and possible OSA was significant in both children and adults, as well as in smoker mothers and fathers.

Au nanoring arrays as surface enhanced Raman spectroscopy substrate for chemical component study of individual atmospheric aerosol particle.

Monolayer-ordered gold nanoring arrays were prepared by ion-sputtering method and used as surface enhanced Raman spectroscopy (SERS) substrates to test the individual atmospheric aerosols particle. Compared to other methods used for testing atmospheric aerosols particles, the collection and subsequent detection in our work is performed directly on the gold nanoring SERS substrate without any treatment of the analyte. The SERS performance can be tuned by changing the depth of the gold nanoring cavity as originating from coupling of dipolar modes at the inner and outer surfaces of the nanorings. The electric field exhibits uniform enhancement and polarization in the ordered Au nanoring substrate, which can improve the accuracy for detecting atmospheric aerosol particles. Combined with Raman mapping, the information about chemical composition of individual atmospheric aerosols particle and distribution of specific components can be presented visually. The results show the potential of SERS in enabling improved analysis of aerosol particle chemical composition, mixing state, and other related physicochemical properties.

Photochemical Oxidation of Water-Soluble Organic Carbon (WSOC) on Mineral Dust and Enhanced Organic Ammonium Formation.

Water-soluble organic carbon (WSOC), which is closely related to biogenic emissions, is of great importance in the atmosphere for its ubiquitous existence and rich abundance. Levoglucosan, a typical WSOC, is usually considered to be stable and thus used as a tracer of biomass burning. However, we found that levoglucosan can be photo-oxidized on mineral dust, with formic acid, oxalic acid, glyoxylic acid, 2,3-dioxopropanoic acid, dicarbonic acid, performic acid, mesoxalaldehyde, 2-hydroxymalonaldehyde, carbonic formic anhydride, and 1,3-dioxolane-2,4-dione detected as main products. Further, we observed the heterogeneous uptake of NH3 promoted by the carboxylic acids stemming from the photocatalytic oxidation (PCO) of levoglucosan. The mineral-dust-initiated PCO of levoglucosan and enhanced heterogeneous uptake of NH3, which are highly influenced by irradiation and moisture conditions, were for the first time revealed. The reaction mechanisms and pathways were studied in detail by diffuse reflection infrared Fourier transform spectroscopy (DRIFTS), high-pressure photon ionization time-of-flight mass spectrometry (HPPI-ToF-MS) and flow reactor systems. Diverse WSOC constituents were studied as well, and the reactivity toward NH3 is related to the number of hydroxyl groups of the WSOC molecules. This work reveals a new precursor of secondary organic aerosols and provides experimental evidence of the existence of organic ammonium salts in atmospheric particles.

Surface-Enhanced Raman Spectroscopy Facilitates the Detection of Microplastics <1 µm in the Environment.

Micro- and nanoplastics are considered one of the top pollutants that threaten the environment, aquatic life, and mammalian (including human) health. Unfortunately, the development of uncomplicated but reliable analytical methods that are sensitive to individual microplastic particles, with sizes smaller than 1 µm, remains incomplete. Here, we demonstrate the detection and identification of (single) micro- and nanoplastics by using surface-enhanced Raman spectroscopy (SERS) with Klarite substrates. Klarite is an exceptional SERS substrate; it is shaped as a dense grid of inverted pyramidal cavities made of gold. Numerical simulations demonstrate that these cavities (or pits) strongly focus incident light into intense hotspots. We show that Klarite has the potential to facilitate the detection and identification of synthesized and atmospheric/aquatic microplastic (single) particles, with sizes down to 360 nm. We find enhancement factors of up to 2 orders of magnitude for polystyrene analytes. In addition, we detect and identify microplastics with sizes down to 450 nm on Klarite, with samples extracted from ambient, airborne particles. Moreover, we demonstrate Raman mapping as a fast detection technique for submicron microplastic particles. The results show that SERS with Klarite is a facile technique that has the potential to detect and systematically measure nanoplastics in the environment. This research is an important step toward detecting nanoscale plastic particles that may cause toxic effects to mammalian and aquatic life when present in high concentrations.

Heterogeneous Formation of Sulfur Species on Manganese Oxides: Effects of Particle Type and Moisture Condition.

The heterogeneous reaction of SO2 on manganese oxides is poorly understood. By means of in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), this study investigated the reaction kinetics and product fractions on four types of manganese oxides. Due to the positive and negative moisture impacts, 68% RH (relative humidity) becomes the most favorable condition for the uptake of SO2. Mn3O4 shows the greatest uptake capacity of SO2, followed by MnO2 and Mn2O3, with that of MnO being the weakest. Curve-fitting procedures were undertaken to further dissect the product spectra. Increased RH facilitates the physical adsorption of SO2 and generally weakens the oxidation capacity of manganese oxides. The oxidation ability is greatest for MnO, followed by MnO2 and Mn3O4, with that of Mn2O3 being the weakest. Additionally, the particle acidity (pH) was estimated by the ionization equilibrium of sulfurous acid and the relative contributions of S(IV) species. MnO and Mn3O4 become more acidic as RH increases while Mn2O3 and MnO2 are the most acidic at 50% RH, which can be attributed to the different uptake capacities of SO2 and H2O on each sample. Overall, for the heterogeneous reaction of SO2 on manganese oxides, both particle type and moisture condition influence the reaction kinetics and product fractions. This work improves the understanding of the heterogeneous process on atmospheric manganese-rich particles.

Klarite as a label-free SERS-based assay: a promising approach for atmospheric bioaerosol detection.

Detecting atmospheric bioaerosols in a quantitative way is highly desirable for public health and safety. This work demonstrates that surface-enhanced Raman spectroscopy (SERS) is a simple and rapid analytical technique for the detection of atmospheric bioaerosols, on a Klarite substrate. For both simulated and ambient bioaerosols, this detection assay results in an increase in the enhancement factor of the Raman signal. We report a strong SERS signal generated by bioaerosols containing living Escherichia coli deposited on Klarite. Furthermore, we demonstrate that SERS mapping can be used to estimate the percentage of airborne, living Escherichia coli. Moreover, Klarite provides differently distinct SERS spectra at different bacterial growth phases, indicating its potential to identify changes occurring in the bacterial envelope. Finally, we applied SERS for the rapid detection of Escherichia coli in ambient bioaerosols without using time-consuming and laborious culture processes. Our results represent rapid, culture-free and label-free detection of airborne bacteria in the real-world environment.

Efficient electrochemical NO reduction to NH3 over metal-free g-C3N4 nanosheets and the role of interface microenvironment.

The ever-increasing NO emission has caused severe environmental issues and adverse effects on human health. Electrocatalytic reduction is regarded as a win-win technology for NO treatment with value-added NH3 generation, but the process is mainly relied on the metal-containing electrocatalysts. Here, we developed metal-free g-C3N4 nanosheets (deposited on carbon paper, named as CNNS/CP) for NH3 synthesis from electrochemical NO reduction under ambient condition. The CNNS/CP electrode afforded excellent NH3 yield rate of 15.1 µmol h-1 cm-2 (2180.1 mg gcat-1 h-1) and Faradic efficiency (FE) of ∼41.5 % at - 0.8 and - 0.6 VRHE, respectively, which were superior to the block g-C3N4 particles and comparable to the most of metal-containing catalysts. Moreover, through adjusting the interface microenvironment of CNNS/CP electrode by hydrophobic treatment, the abundant gas-liquid-solid triphasic interface improved NO mass transfer and availability, which enhanced NH3 production and FE to about 30.7 µmol h-1 cm-2 (4424.2 mg gcat-1 h-1) and 45.6 % at potential of - 0.8 VRHE. This study opens a novel pathway to develop efficient metal-free electrocatalysts for NO electroreduction and highlights the importance of electrode interface microenvironment in electrocatalysis.

Comparative efficacy and safety of non-polymyxin antibiotics against nosocomial pneumonia, complicated intra-abdominal infection, or complicated urinary tract infection: A network meta-analysis of randomised clinical trials.

OBJECTIVES: The increasing epidemic of infections caused by drug-resistant Gram-negative bacteria has led to the development of several antibiotic therapies. Owing to the scarcity of head-to-head comparisons of current and emerging antibiotics, the present network meta-analysis aimed to compare the efficacy and safety of antibiotics in patients with nosocomial pneumonia, complicated intra-abdominal infection, or complicated urinary tract infection. METHODS: Two independent researchers systematically searched databases up to August 2022 and included 26 randomised controlled trials that fulfilled the inclusion criteria. The protocol was registered in the Prospective Register of Systematic Reviews, PROSPERO (CRD42021237798). The frequentist random effects model (R version 3.5.1, netmeta package) was utilized. The DerSimonian-Laird random effects model was used to estimate heterogeneity. The calculated P-score was applied to rank the interventions. Additionally, inconsistencies, publication bias, and subgroup effects were assessed in the present study to avoid bias. RESULTS: There was no significant difference among included antibiotics in terms of clinical response and mortality, probably because most antibiotic trials were designed to be non-inferior. In terms of P-score ranking, carbapenems may be the recommended choice considering both adverse events and clinical responses. On the other hand, for carbapenem-sparing options, ceftolozane-tazobactam was the preferred antibiotic for nosocomial pneumonia; eravacycline, for complicated intra-abdominal infection; and cefiderocol, for complicated urinary tract infection. CONCLUSION: Carbapenems may be preferable options in terms of safety and efficacy for the treatment of Gram-negative bacterial complicated infections. However, to preserve the effectiveness of carbapenems, it is important to consider carbapenem-sparing regimens.

Surface-enhanced Raman spectroscopy for bioanalysis and diagnosis.

In recent years, bioanalytical surface-enhanced Raman spectroscopy (SERS) has blossomed into a fast-growing research area. Owing to its high sensitivity and outstanding multiplexing ability, SERS is an effective analytical technique that has excellent potential in bioanalysis and diagnosis, as demonstrated by its increasing applications in vivo. SERS allows the rapid detection of molecular species based on direct and indirect strategies. Because it benefits from the tunable surface properties of nanostructures, it finds a broad range of applications with clinical relevance, such as biological sensing, drug delivery and live cell imaging assays. Of particular interest are early-stage-cancer detection and the fast detection of pathogens. Here, we present a comprehensive survey of SERS-based assays, from basic considerations to bioanalytical applications. Our main focus is on SERS-based pathogen detection methods as point-of-care solutions for early bacterial infection detection and chronic disease diagnosis. Additionally, various promising in vivo applications of SERS are surveyed. Furthermore, we provide a brief outlook of recent endeavours and we discuss future prospects and limitations for SERS, as a reliable approach for rapid and sensitive bioanalysis and diagnosis.

Ultrasound-boosted selectivity of CO in CO2 electrochemical reduction.

Among the possible products of CO2 electrochemical reduction, CO plays a unique and vital role, which can be an ideal feedstock for further reduction to C2+ products, and also the important component of syngas that can be used as feedstock for value-added chemicals and fuels. However, it is still a challenge to tune the CO selectivity on Cu electrode. Here we newly construct an ultrasound-assisted electrochemical method for CO2 reduction, which can tune the selectivity of CO2 to CO from less than 10% to >80% at -1.18 V versus (vs.) reversible hydrogen electrode (RHE). The partial current density of CO production is significantly improved by 15 times. By in-situ Raman study, the dominating factor for the improved CO production is attributed to the accelerated desorption of *CO intermediate. This work provides a facile method to tune the product selectivity in CO2 electrochemical reduction.

Correction: Surface-enhanced Raman spectroscopy for bioanalysis and diagnosis.

Correction for 'Surface-enhanced Raman spectroscopy for bioanalysis and diagnosis' by Muhammad Ali Tahir et al., Nanoscale, 2021, 13, 11593-11634, DOI: .

New insights into the role of sulfite in BiOX photocatalytic pollutants elimination: In-operando generation of plasmonic Bi metal and oxygen vacancies.

Photocatalysis has been regarded as a sustainable strategy for wastewaters remediation, and sulfite addition could significantly accelerate the photocatalytic performances. However, the related mechanisms are still not well understood. Here, we for the first time found that plasmonic Bi and oxygen vacancies were in-operando generated on BiOX (X = Cl, Br, I) in the presence of sulfite under light irradiation. The oxidative degradation rate constants of 4-nitrophenol, bisphenol A, and phenol were improved by about 11.5, 4.7, and 12.2 times on BiOBr and 9.1, 1.6, and 3.1 times on BiOCl with addition of 5 mM sulfite, while the photocatalytic reduction rate of 4-nitrophenol to 4-aminophenol was promoted by approximate 31.7 times on BiOI. The results indicated that sulfite could improve the photooxidation ability of BiOBr and BiOCl and the photoreduction performance of BiOI, resulted from the improved light absorption and separation of photogenerated charge carriers. This work can provide exploratory platforms for understanding and maximizing the sulfite-assisted BiOX photocatalysis.

The high-resolution estimation of sulfur dioxide (SO2) concentration, health effect and monetary costs in Beijing.

Severe air pollution episodes with high SO2 loading have been frequently observed during the last decades in Beijing and have caused a noticeable damage to human health. To advance the spatiotemporal prediction of SO2 exposure in Beijing, we developed the monthly land use regression (LUR) models using daily SO2 concentration data collected from 34 monitoring stations during 2016 and 7 categories of potential independent variables (socio-economic factors, traffic and transport, emission source, land use, meteorological data, building morphology and Geographic location) in Beijing. The average adjusted R2 of 12 final LUR models was 0.62, and the root-mean-squared error (RMSE) was 4.12 µg/m3. The LOOCV R2 and RMSE of LUR models reached 0.56 and 5.43 µg/m3, respectively, suggesting that the LUR models achieved the satisfactory performance. The prediction results suggested that the average SO2 level in Beijing was 11.06 µg/m3 with the highest one up to 22.49 µg/m3 but the lowest one down to 3.86 µg/m3. The SO2 exposure showed strong spatial heterogeneity, which was much higher in the southern area than that in the northern in Beijing. The mortality and morbidity due to the excessive SO2 concentration were estimated to be 73 (95% CI:(38-125)) and 27854 (95% CI:(13852-41659)) cases per year in Beijing, leading to economic cost of 35.76 (95% CI:(16.45-54.06)) and 441.47 (95% CI:(318.31-562.04)) million RMB Yuan in 2016, respectively. This study clarified the intra- and inter-regional transport modeling of the SO2 pollution in Beijing and supplied an important support for the future air-quality and public health management strategies.

Brown carbon: An underlying driving force for rapid atmospheric sulfate formation and haze event.

The rapid sulfate formation is a crucial factor determining the explosive growth of fine particles and the frequent occurrence of severe haze events in China. Recent field observations also show that brown carbon is one of the most critical components in aerosol particles sampled during haze episodes. To this day, there is limited knowledge that accesses the role of brown carbon in atmospheric chemistry. In fact, these carbonaceous particulate matters, mainly derived from forest fires, biomass burning, and biogenic release, can act as photosensitizers and produce varieties of active intermediates to alter oxidation capacity. Experimental results in this work provide evidence that hydroxyl radical (∙OH) stems from brown carbon proxies fulvic acid /humic acid (FA/HA) upon irradiation, leading to rapid SO2 oxidation on brown carbon particles in the atmosphere. Further correlation analyses for sulfate formation and chromophore properties of 12 model compounds demonstrate that brown carbon particles with higher aromaticity and E2/E3 (the ratio of absorbance at 254 nm to that at 365 nm) would facilitate ∙OH production and SO2 photo-oxidation. Uptake coefficient measurements and sulfate production rate estimation indicate that brown carbon could gain importance in atmospheric SO2 oxidation. A better understanding of SO2 uptake kinetics on brown carbon surfaces favors in defining new regulations to improve air quality and reduce the harmful effects of haze events on resident health and the environment.

Complete Photocatalytic Mineralization of Microplastic on TiO2 Nanoparticle Film.

Recently, the environmental impacts of microplastics have received extensive attention owing to their accumulation in the environment. However, developing efficient technology for the control and purification of microplastics is still a big challenge. Herein, we investigated the photocatalytic degradation of typical microplastics such as polystyrene (PS) microspheres and polyethylene (PE) over TiO2 nanoparticle films under UV light irradiation. TiO2 nanoparticle film made with Triton X-100 showed complete mineralization (98.40%) of 400-nm PS in 12 h, while degradation for varying sizes of PS was also studied. PE degradation experiment presented a high photodegradation rate after 36 h. CO2 was found as the main end product. The degradation mechanism and intermediates were studied by in situ DRIFTS and HPPI-TOFMS, showing the generation of hydroxyl, carbonyl, and carbon-hydrogen groups during the photodegradation of PS. This study provides a green and cost-efficient strategy for the control of microplastics contamination in the environment.

The application of Raman spectroscopy combined with multivariable analysis on source apportionment of atmospheric black carbon aerosols.

Source apportionment studies become increasingly crucial for black carbon (BC) in atmospheric particulate matters given its linkage with adverse public health and climate impacts. In this work, a facile and rapid method using Raman spectra combined with stepwise discriminant analysis (SDA) was proposed to identify and quantify the contributions of atmospheric BC sources. Four BC samples from biomass burning, coal combustion, gasoline and diesel vehicle emission were characterized by Raman spectra. The SDA model was established based on 10 parameters with significant differences (p < 0.05), giving an accuracy of 83% with a cross-validation rate of 80%. Utilizing four suggested discriminant variables from SDA model, vehicle emission was predicted as the dominant contributor to ambient BC particles, among which gasoline contributed much higher than diesel at an urban road intersection in Shanghai, China. This new method shows great potential to classify and investigate the sources of atmospheric BC aerosols and provide more effective information on air pollution control measures.

A Green Desulfurization Technique: Utilization of Flue Gas SO2 to Produce H2 via a Photoelectrochemical Process Based on Mo-Doped BiVO4.

A green photoelectrochemical (PEC) process with simultaneous SO2 removal and H2 production has attracted an increasing attention. The proposed process uses flue gas SO2 to improve H2 production. The improvement of the efficiency of this process is necessary before it can become industrial viable. Herein, we reported a Mo modified BiVO4 photocatalysts for a simultaneous SO2 removal and H2 production. And the PEC performance could be significantly improved with doping and flue gas removal. The evolution rate of H2 and removal of SO2 could be enhanced by almost three times after Mo doping as compared with pristine BiVO4. The enhanced H2 production and SO2 removal is attributed to the improved bulk charge carrier transportation after Mo doping, and greatly enhanced oxidation reaction kinetics on the photoanode due to the formation of [Formula: see text] after SO2 absorption by the electrolyte. Due to the utilization of SO2 to improve the production of H2, the proposed PEC process may become a profitable desulfurization technique.