High light triggers flavonoid and polysaccharide synthesis through DoHY5-dependent signaling in Dendrobium officinale.

Dendrobium officinale is edible and has medicinal and ornamental functions. Polysaccharides and flavonoids, including anthocyanins, are important components of D. officinale that largely determine the nutritional quality and consumer appeal. There is a need to study the molecular mechanisms regulating anthocyanin and polysaccharide biosynthesis to enhance D. officinale quality and its market value. Here, we report that high light (HL) induced the accumulation of polysaccharides, particularly mannose, as well as anthocyanin accumulation, resulting in red stems. Metabolome and transcriptome analyses revealed that most of the flavonoids showed large changes in abundance, and flavonoid and polysaccharide biosynthesis was significantly activated under HL treatment. Interestingly, DoHY5 expression was also highly induced. Biochemical analyses demonstrated that DoHY5 directly binds to the promoters of DoF3H1 (involved in anthocyanin biosynthesis), DoGMPP2, and DoPMT28 (involved in polysaccharide biosynthesis) to activate their expression, thereby promoting anthocyanin and polysaccharide accumulation in D. officinale stems. DoHY5 silencing decreased flavonoid- and polysaccharide-related gene expression and reduced anthocyanin and polysaccharide accumulation, whereas DoHY5 overexpression had the opposite effects. Notably, naturally occurring red-stemmed D. officinale plants similarly have high levels of anthocyanin and polysaccharide accumulation and biosynthesis gene expression. Our results reveal a previously undiscovered role of DoHY5 in co-regulating anthocyanin and polysaccharide biosynthesis under HL conditions, improving our understanding of the mechanisms regulating stem color and determining nutritional quality in D. officinale. Collectively, our results propose a robust and simple strategy for significantly increasing anthocyanin and polysaccharide levels and subsequently improving the nutritional quality of D. officinale.

Drought Stress Induced Different Response Mechanisms in Three Dendrobium Species under Different Photosynthetic Pathways.

Many Dendrobium species, which hold a high status and value in traditional Chinese medicine, grow on barks and rocks in the wild, often encountering harsh environments and facing droughts. However, the molecular mechanisms underlying the shift in the photosynthetic pathway induced by drought remain unclear. To address this issue, three Dendrobium species with different photosynthetic pathways were selected for sequencing and transcriptome data analysis after drought treatment. The findings included 134.43 GB of sequencing data, with numerous Differentially Expressed Genes (DEGs) exhibiting different response mechanisms under drought stress. Gene Ontology (GO)-KEGG-based enrichment analysis of DEGs revealed that metabolic pathways contributed to drought tolerance and alterations in photosynthetic pathways. Phosphoenolpyruvate Carboxylase (PEPC) was subjected to phylogenetic tree construction, sequence alignment, and domain analysis. Under drought stress, variations were observed in the PEPC gene structure and expression among different Dendrobium species; the upregulation of Dc_gene2609 expression may be caused by dof-miR-384, which resulted in the shift from C3 photosynthesis to CAM, thereby improving drought tolerance in Dendrobium. This study revealed the expression patterns and roles of PEPC genes in enhancing plant drought tolerance and will provide an important basis for in-depth research on Dendrobium's adaptation mechanisms in arid environments.

Mixing states and secondary formation processes of organic nitrogen-containing single particles in Guangzhou, China.

Organic nitrogen (ON) compounds play a significant role in the light absorption of brown carbon and the formation of organic aerosols, however, the mixing state, secondary formation processes, and influencing factors of ON compounds are still unclear. This paper reports on the mixing state of ON-containing particles based on measurements obtained using a high-performance single particle aerosol mass spectrometer in January 2020 in Guangzhou. The ON-containing particles accounted for 21% of the total detected single particles, and the particle count and number fraction of the ON-containing particles were two times higher at night than during the day. The prominent increase in the content of ON-containing particles with the enhancement of NOx mainly occurred at night, and accompanied by high relative humidity and nitrate, which were associated with heterogeneous reactions between organics and gaseous NOx and/or NO3 radical. The synchronous decreases in ON-containing particles and the mass absorption coefficient of water-soluble extracts at 365 nm in the afternoon may be associated with photo-bleaching of the ON species in the particles. In addition, the positive matrix factorization analysis found five factors dominated the formation processes of ON particles, and the nitrate factor (33%) mainly contributed to the production of ON particles at night. The results of this study provide unique insights into the mixing states and secondary formation processes of the ON-containing particles.

Cell-free protein synthesis of CD1E and B2M protein and in vitro interaction.

CD1E, one of the most important glycolipid antigens on T cell membranes, is required for glycolipid antigen presentation on the cell surface. Cell-based recombinant expression systems have many limitations for synthesizing transmembrane proteins such as CD1E, including low protein yields and miss folding. To overcome these challenges, here we successfully synthesized high-quality soluble CD1E using an E.coli cell-free protein synthesis system (CFPS) with the aid of detergent. Following purification by Ni2+ affinity chromatography, we were able to obtain CD1E with ≥90% purity. Furthermore, we used the string website to predict the protein interaction network of CD1E and identified a potential binding partner━B2M. Similarly, we synthesized soluble B2M in the E.coli CFPS. Finally, we verified the interaction between CD1E and B2M by using Surface Plasmon Resonance (SPR). Taken together, the methods described here provide an alternative way to obtain active transmembrane protein and may facilitate future structural and functional studies on CD1E.

Comparative Analysis of Water-Soluble Polysaccharides from Dendrobium Second Love 'Tokimeki' and Dendrobium nobile in Structure, Antioxidant, and Anti-Tumor Activity In Vitro.

With potential anti-tumor and antioxidant properties, the polysaccharide content of D. nobile is relatively lower than that of the other medicinal Dendrobium. To find high-content polysaccharide resources, the polysaccharide (DHPP-Ⅰs) was prepared from D. Second Love 'Tokimeki' (a D. nobile hybrid) and compared with DNPP-Ⅰs from D. nobile. DHPP-Is (Mn 31.09 kDa) and DNPP-Is (Mn 46.65 kDa) were found to be O-acetylated glucomannans (-Glcp-(1,4) and O-acetylated-D-Manp-(1,4) backbones), analogous to other Dendrobium polysaccharides. DHPP-Ⅰs had higher glucose content (31.1%) and a lower degree (0.16) of acetylation than DNPP-Ⅰs (15.8%, 0.28). Meanwhile, DHPP-Ⅰs and DNPP-Ⅰs had the same ability in the radical scavenging assay, which was milder than the control of Vc. Both DHPP-Is and DNPP-Is inhibited SPC-A-1 cell proliferation in vitro, with obvious differences in dose concentrations (0.5-2.0 mg/mL) and treatment times (24-72 h). Therefore, the antioxidant activity of DHPP-Ⅰs and DNPP-Ⅰs is not associated with distinction in anti-proliferative activity. As a glucomannan derived from non-medicinal Dendrobium, DHPP-Ⅰs has similar bioactivity to other medicinal Dendrobium, and this could serve as a starting point for studying the conformational-bioactivity relationship of Dendrobium polysaccharides.

[Meta-analysis for the association of GJB2 gene p.V37I variant and its types with the risk of deafness].

OBJECTIVE: To assess the association of c.109G>A (p.V37I) variant of the GJB2 gene and its types with the risk of deafness. METHODS: PubMed, Embase, Cochrane Library, CNKI, Wanfang, and VIP database were searched for cases with GJB2 gene c.109G>A (p.V37I) variant and its compounds with variants of other sites from case-control studies, cohort studies and cross-sectional studies. The search time was from the establishment of database to April 2021. Two researchers have independently screened the literature according to the inclusion and exclusion criteria, extracted the data, and evaluated the included studies according to the criteria. Stata 12.0 software was used for the meta-analysis and publication bias analysis, and a sensitivity analysis was also carried out when necessary. RESULTS: A total of 22 articles (17 in English and 5 in Chinese) were included. There were 7455 cases in the deafness group and 10 464 cases in the control group. The results of meta-analysis showed the c.109G>A (p.V37I) variant to be strongly associated with the risk of deafness (OR: 3.56, 95%CI: 2.31-5.47, P < 0.001). Analysis based on the mutational type also suggested c.109G>A (p.V37I) homozygosity (OR: 11.36, 95%CI: 5.93-21.74, P < 0.001) and compound loss of heterozygosity mutations (OR: 9.27, 95%CI: 3.97-21.64, P < 0.001) to be strongly associated with the risk of deafness. By contrast, heterozygous c.109G>A (p.V37I) variant (OR: 1.20, 95%CI: 0.72-2.00, P = 0.478) and compound heterozygous missense mutation (OR: 1.54, 95%CI: 0.98-2.44, P = 0.063) are not strongly associated with the risk. CONCLUSION: The homozygous c.109G>A (p.V37I) variants of the GJB2 gene and its compound deletional mutation with another GJB2 allele can significantly increase the risk of deafness. Heterozygous c.109G>A (p.V37I) variant of the GJB2 gene or its compound with a missense mutation of another GJB2 allele do not increase the risk.

Assessing nursing quality in paediatric intensive care units: a cross-sectional study in China.

BACKGROUND: Nursing-sensitive indicators are considered effective tools for improving the quality of care in hospitals. However, these have not been used in paediatric intensive care units (PICUs) in China. AIM: To develop nursing-sensitive indicators for PICUs and to assess the quality of nursing in PICUs in China based on the nursing-sensitive indicators. DESIGN: Multi-centre, cross-sectional study. METHODS: Structure, process and outcome indicators were developed and measured from 1 January to 31 March 2014 in seven PICUs in China. RESULTS: The structure indicators showed that one nurse cared for an average of 2·8 patients in a PICU, and 44% of nurses had a bachelor's degree. The process indicators revealed that hand-washing compliance varied across PICUs, whereas pain management and physical restraint have not been adequately addressed in China. The outcome indicators revealed that the incidence rates of ventilator-associated pneumonia and central-line-associated blood stream infections were 2·96 and 0·7, respectively, per 1000 device days. Patients were intubated for a total of 4392 mechanical ventilator days, and 32 patients (7·29‰) had an unplanned extubation. Nurses were moderately satisfied in their jobs (3·1 ± 0·3), and parents reported that nurses provide high quality of care. CONCLUSIONS: This study developed and used nursing-sensitive indicators to assess the quality of nursing in PICUs in China, which provided a reference for national and international comparisons of nursing quality in PICUs. Nursing staffing levels and education should be improved. Pain management and physical restraints should be regulated in China's PICUs. Nurse managers need to explore staff attitudes towards implementation of family-centred care. The development of a national database of nursing quality indicators can contribute to quality and safety improvement. RELEVANCE TO CLINICAL PRACTICE: This study developed a set of nursing-sensitive indicators, and these indicators were used to assess and improve the quality of nursing in PICUs.

Stability and delay sensitivity of neutral fractional-delay systems.

This paper generalizes the stability test method via integral estimation for integer-order neutral time-delay systems to neutral fractional-delay systems. The key step in stability test is the calculation of the number of unstable characteristic roots that is described by a definite integral over an interval from zero to a sufficient large upper limit. Algorithms for correctly estimating the upper limits of the integral are given in two concise ways, parameter dependent or independent. A special feature of the proposed method is that it judges the stability of fractional-delay systems simply by using rough integral estimation. Meanwhile, the paper shows that for some neutral fractional-delay systems, the stability is extremely sensitive to the change of time delays. Examples are given for demonstrating the proposed method as well as the delay sensitivity.

[Effect of ß-lactamase detection on reducing the incidence of antibiotic-associated diarrhea in children with severe bacterial pneumonia].

OBJECTIVE: To study the effect of ß-lactamase (BLs) detection and ß-lactam/ß-lactamase inhibitor (BL/BLI) on the incidence of antibiotic-associated diarrhea (AAD) in children with severe bacterial pneumonia. METHODS: The clinical data of the children with bacterial severe pneumonia were retrospectively studied. Of all the patients, 248 using amoxicillin/clavulanate but without BLs detection and 323 using amoxicillin (BLs negative) or amoxicillin/clavulanate (BLs positive) were used as the amoxicillin group; 208 patients using piperacillin/tazobactam but without BLs detection and 291 patients using piperacillin (BLs negative) or piperacillin/tazobactam (BLs positive) were used as the piperacillin group; and 191 patients using cefoperazone/sulbactam but without BLs detection and 341 patients using cefoperazone (BLs negative) or cefoperazone/sulbactam (BLs positive) were used as the cefoperazone group. The incidence and clinical symptoms of AAD between the undetected and detected BLs patients were compared. RESULTS: The incidences of AAD in the amoxicillin, piperacillin and cefoperazone groups without BLs detection groups were significantly higher than those in the corresponding groups with negative or positive results of BLs detection (P<0.01). The durations of diarrhea, antibiotic use and hospitalization stay in AAD patients receiving BLs detection were shorter than in those without receiving BLs detection (P<0.01). CONCLUSIONS: It is very important to detect BLs for reducing the incidence and relieving symptoms of AAD in children with severe bacterial pneumonia.

Single particle mass spectral signatures from on-road and non-road vehicle exhaust particles and their application in refined source apportionment using deep learning.

With advances in vehicle emission control technology, updating source profiles to meet the current requirements of source apportionment has become increasingly crucial. In this study, on-road and non-road vehicle particles were collected, and then the chemical compositions of individual particles were analyzed using single particle aerosol mass spectrometry. The data were grouped using an adaptive resonance theory neural network to identify signatures and establish a mass spectral database of mobile sources. In addition, a deep learning-based model (DeepAerosolClassifier) for classifying aerosol particles was established. The objective of this model was to accomplish source apportionment. During the training process, the model achieved an accuracy of 98.49 % for the validation set and an accuracy of 93.36 % for the testing set. Regarding the model interpretation, ideal spectra were generated using the model, verifying its accurate recognition of the characteristic patterns in the mass spectra. In a practical application, the model performed hourly source apportionment at three specific field monitoring sites. The effectiveness of the model in field measurement was validated by combining traffic flow and spatial information with the model results. Compared with other machine learning methods, our model achieved highly automated source apportionment while eliminating the need for feature selection, and it enables end-to-end operation. Thus, in the future, it can be applied in refined and online source apportionment of particulate matter.

Effect of Black Tea Polysaccharides on Alleviating Type 2 Diabetes Mellitus by Regulating PI3K/Akt/GLUT2 Pathway.

The bioactivity of tea polysaccharides (TPs) has been widely reported, but studies to date have focused on green tea. Some human health investigations have implied that black tea may possess potential antidiabetic effects, but less is known about their potential role and related antidiabetic mechanism. The present study was, therefore, conducted to investigate the chemical properties and antidiabetic activity of TPs from black tea. Monosaccharide composition revealed that Alduronic acid (77.8 mol%) considerably predominated in the fraction. TP conformation analysis indicated that three components in TPs were all typical of high-branching structures. Oral administration of TPs could effectively alleviate fasting blood glucose in type 2 diabetes mellitus (T2D) mice, with the values 23.6 ± 1.42, 19.6 ± 2.25, and 16.4 ± 2.07 mmol/L in the 200, 400, and 800 mg/kg·BW groups, respectively. Among these TPs groups, the 800 mg/kg·BW groups significantly decreased by 37.88% when compared with the T2D+water group (p < 0.05). Further studies demonstrated that TP treatment upregulated the expression of p-Akt/p-PI3K (p < 0.001). Additionally, TP treatment significantly promoted glucose transporter protein 2 (GLUT2) translocation in the liver (p < 0.001). These findings suggest that TPs from black tea protect against T2D by activating PI3K/Akt/GLUT2 signaling and might serve as a novel therapeutic candidate for T2D.

Pt/graphene-CNTs nanocomposite based electrochemical sensors for the determination of endocrine disruptor bisphenol A in thermal printing papers.

A facile and green method was developed to synthesize the graphene-carbon nanotubes (Gr-CNTs) nanocomposite with a sandwich lamination structure. Pt nanoparticles were loaded on the as-synthesized Gr-CNTs nanocomposite to prepare an electrochemical sensor for determining bisphenol A (BPA) in thermal printing paper. The electrochemical behavior of BPA on the Pt/Gr-CNTs nanocomposite was investigated by cyclic voltammetry (CV) and chronocoulometry (CC). The direct determination of BPA was accomplished by using differential pulse voltammetry (DPV) under optimized conditions. The oxidation peak current was proportional to the BPA concentration in the range from 6.0 × 10(-8) to 1.0 × 10(-5) M and 1.0 × 10(-5) to 8.0 × 10(-5) M with a correlation coefficient of 0.987 and 0.998, respectively. The detection limit was 4.2 × 10(-8) M (S/N = 3). The fabricated electrode showed good reproducibility, stability and selectivity. The proposed method was successfully applied to determine BPA in thermal printing papers samples and the results were satisfactory.

Prevalence, risk factors, and clinical correlates of anxiety, depression, and sleep disorders in chaperones for children in the emergency department in China during COVID-19.

The outbreak of novel coronavirus pneumonia in Wuhan, Hubei Province, in 2019 and its rapid spread across the country caused severe public panic in China. The purpose of this study was to investigate the mental health problems of children's chaperones at the emergency clinic during the coronavirus disease 2019 (COVID-19) outbreak and to analyze the related influencing factors. A total of 260 chaperones for children in the emergency department participated in this cross-sectional study through the questionnaire constellation platform. The survey period was from February to June 2021. Information collected included demographic data and mental health scales. The Self-Assessment Scale for Anxiety, the Self-Rating Scale for Depression, and the Pittsburgh Sleep Quality Index assessed anxiety, depression, and sleep quality, respectively. Logistic regression was used to analyze influential factors associated with mental health problems. The prevalence of depression, anxiety, and sleep disorders among family members accompanying children attending the emergency room was 41.54%, 20.00%, and 93.08%, respectively, with 21.54% of family members suffering from moderate sleep disorders. Univariate analysis showed that being in Wuhan or not during the city closure (X2 = 8.61, P < .01) was strongly associated with the occurrence of depression; female (X2 = 4.87, P = .03), working or not (X2 = 6.39, P = .01) and fear of going to the hospital (X2 = 7.80, P = .01) were key factors for the occurrence of anxiety symptoms; Knowledge of transmission routes and prevention of COVID-19 (X2 = 12.56, P = .03) was a key factor for sleep disorders; logistic stepwise regression analysis showed that fear of going to the hospital was a risk factor for anxiety symptoms (odds ratio = 2.51, P < .01, 95% confidence interval = 1.30-4.85). Our findings suggest that mental health problems were prevalent among family members accompanying children attending the emergency department during the COVID-19 outbreak, with a high prevalence of sleep disturbances in particular. Relevant factors included presence or absence in Wuhan during the outbreak closure, gender, work or absence, and fear of hospital visits. There is a need to focus on the mental health distress of the chaperones for children in the emergency department, and to provide timely intervention and diversion.

Nursing care for children with fulminant myocarditis treated with extracorporeal membrane oxygenation.

To summarize the nursing experience of treating pediatric fulminant myocarditis with extracorporeal membrane oxygenation (ECMO). The intensive care unit of our hospital treated 6 children with fulminant myocarditis with ECMO from 2019 to 2022. The main nursing measures included establishing an ECMO rescue team, preparing before initiation of ECMO, management of arterial and venous catheters, enteral nutrition support, reducing the risk of infection aggravation, anticoagulation management, prevention of bleeding and thrombosis, management of ECMO pump failure, and post-ECMO care. One child's family abandoned treatment and left the hospital, while the other 5 children were transferred to the cardiovascular department after stable weaning from ECMO and continued treatment, with good condition, and eventually discharged. Pediatric fulminant myocarditis has a high mortality rate, but detailed evaluation and nursing care can improve the outcome of these patients.

Isolation and characterization of a nephroprotective polysaccharide from Dendrobium chrysotoxum Lindl against LPS-induced acute kidney injury mice.

The structure and bioactivity of a novel polysaccharide from Dendrobium Chrysotoxum Lindl (DCP-1) were investigated. The crude polysaccharides of Dendrobium Chrysotoxum Lindl (DCP) were extracted by hot water extraction, and the protein was removed by enzymatic hydrolysis and Sevage. After purification, the chemical structure of polysaccharides was identified by infrared spectroscopy, methylation analysis and nuclear magnetic resonance spectroscopy. Then, a mouse model of acute kidney injury (AKI) was constructed using lipopolysaccharide (LPS), and pretreated with DCP. Structure characterization demonstrated that the number-average molecular weight and mass average molar mass of DCP-1 were 28.43 kDa and 15.00 kDa, respectively. DCP-1 mainly consisted of mannose (37.8 %) and glucose (55.6 %). The main linkage types of DCP-1 were contained 1,4-Linked Manp and 1,4-Linked Glcp. And DCP-1 was demonstrated to be an O-acetylglucomannan with ß-ᴅ-configuration in pyranoid form. Besides, the bioactivity of DCP was further investigated. The results showed that DCP exhibited notable anti-inflammatory activity in LPS-induced AKI mice. After treated with DCP, the creatinine (CREA) and urea nitrogen (BUN) in serum were successfully down-regulated in AKI mice. DCP treatment prevented the characteristic morphological changes of LPS-induced renal tubular injury. The results showed that DCP treatment significantly reduced the concentration of oxidative damage indicators (MDA, SOD) and the expression of inflammatory indices (TNF-α, IL-6, MCP-1, COX-2). In general, the newly extracted polysaccharide DCP showed excellent nephroprotective effect, which enabled it to be an ideal natural medicine for kidney diseases therapy.

Long-Term Observation of Mixing States and Sources of Vanadium-Containing Single Particles from 2020 to 2021 in Guangzhou, China.

The distribution of vanadium (V) in aerosols is commonly used to track ship exhaust emissions, yet the atmospheric abundance of V has been greatly reduced due to the implementation of a clean fuel policy. Recent research mainly discussed the chemical compositions of ship-related particles during specific events, yet few studies focus on the long-term changes of V in the atmosphere. In this study, a single-particle aerosol mass spectrometer was used to measure V-containing particles from 2020 to 2021 in Huangpu Port in Guangzhou, China. The long-term trend of the particle counts of V-containing particles declined annually, but the relative abundance of V-containing particles in the total single particles increased in summer due to the influence of ship emissions. Positive matrix factorization revealed that in June and July 2020, 35.7% of the V-containing particles were from ship emissions, followed by dust and industrial emissions. Furthermore, more than 80% of the V-containing particles were found mixing with sulfate and 60% of the V-containing particles were found mixing with nitrate, suggesting that the majority of the V-containing particles were secondary particles processed during the transport of ship emissions to urban areas. Compared with the small changes in the relative abundance of sulfate in the V-containing particles, the relative abundance of nitrate exhibited clear seasonal variations, with a high abundance in winter. This may have been due to the increased production of nitrate from high concentrations of precursors and a suitable chemical environment. For the first time, the long-term trends of V-containing particles in two years are investigated to demonstrate changes in their mixing states and sources after the clean fuel policy, and to suggest the cautious application of V as an indicator of ship emissions.

Quantitative evidence from VOCs source apportionment reveals O3 control strategies in northern and southern China.

Ground-level ozone (O3) pollution has received widespread attention because its rising trend and adverse ecological impacts. However, the extremely strong photochemical reactions of its precursor volatile organic compounds (VOCs) increase the difficulty of reducing VOCs emissions to alleviate O3. Here, we carried out a one-year comprehensive observation in two representative cities, Tianjin (TJ, Northern China) and Guangzhou (GZ, Southern China). By revealing the concentration characteristics of three different types of VOCs, i.e., initial VOCs without photochemical reaction (In-VOCs), consumed VOCs (C-VOCs), and measured VOCs after the reaction (M-VOCs), we elucidated the important role of C-VOCs in the formation of O3. Although the overall trends were similar in both cities, the average concentration level of VOCs in GZ was 8.2 ppbv higher than that in TJ, and the photochemical loss of VOCs was greater by 2.2 ppbv. In addition, various drivers affecting O3 generation from C-VOCs were specifically explored, and it was found that most alkenes of TJ were key substances for rapid O3 formation compared to aromatics of GZ. Meanwhile, favorable meteorological conditions such as high temperature (T > 31 °C in TJ, and T > 33 °C in GZ), low relative humidity (56% in TJ and 45% in GZ), and stable atmospheric environment (proper pressure and gentle wind speed) also contribute to the generation of O3. More importantly, we combined chemical kinetics and receptor model to quantify the three-type VOCs source contributions and assess the potential impact of C-VOCs sources on O3 production, thus proposing environmental abatement technologies corresponding to the three types of VOCs. The differences in the comparison results of the three-type VOCs highlight the need to reduce O3 pollution from C-VOCs sources, which provides insights for future clean air policies development.

RID serve as a more appropriate measure than phenol sulfuric acid method for natural water-soluble polysaccharides quantification.

With structural diversity of water-soluble polysaccharides, their precise quantitative analysis by phenol­sulfuric acid method becomes more difficult and challenging. In this study, the quantification analysis of dextran and glucose in phenol sulfuric acid method was compared in this paper. When the concentration is below 90 µg/mL, the quantification of glucose is close to theoretical value, however, glucose derivatives have significantly different absorption. Later, quantitative factors of water-soluble polysaccharide in RID measurement were investigated. The optimum temperature was 40 °C and linear range was 0.3125-10.0 mg/mL in RID for dextrans (1.0-500 kDa) and glucose derivatives. Method validation studies of the RID method were further performed and compared to conventional phenol sulfuric acid method, which demonstrated that RID measurement is more reliable and satisfactory method. The intervention of water-soluble impurity in RID response should be well control below 6% (w/w). By comparison, the RID measurement could well alleviate drawbacks in phenol­sulfuric acid method.

Insights into the different mixing states and formation processes of amine-containing single particles in Guangzhou, China.

The formation processes of particulate amines are closely related to their emission sources and secondary reactions, which can be revealed through the investigation of their real-time mixing states in individual particles. The mixing states of methylamine (MA)-, trimethylamine (TMA)-, and diethylamine (DEA)-containing particles were studied using a high-performance single particle aerosol mass spectrometer (HP-SPAMS) in Guangzhou, China, in January 2020. The sharp increase in TMA particles was found to be closely associated with the increase in the ambient relative humidity (RH), while the MA- and DEA-containing particles were not similarly influenced by the changes in the RH. The prominent enrichment of secondary oxygenated organics in DEA particles during the daytime was consistent with the active period of photochemistry, implying that the sharp decrease in DEA particles in the afternoon was likely due to photo-oxidation of the DEA. The number fraction (Nf) of DEA particles, the Nf of the nitrate in the DEA particles, and the abundance of nitrate increased as the NOx content all increased during the nighttime, suggesting that the formation of DEA·HNO3 salt was the dominant pathway of particulate DEA production. These results are consistent with our previous measurements in Nanjing, confirming the general and distinct mixing states of TMA and DEA particles. Positive matrix factorization analysis revealed that the total fraction of the more oxidized organics factor and the less oxidized organics factor were much higher in the DEA particles (26.9 %) than in the TMA particles (9 %), confirming the significant enrichment of oxygenated species in the DEA particles. The different mixing states of the amines revealed the unique response of each type of amine to the same atmospheric environment, and the prominent mixing states of the DEA with secondary oxygenated species suggest the potential role of DEA in tracing the evolution of organic aerosols.

[Analysis of a Typical Ozone Pollution Process in Guangzhou in Winter].

This study focused on an ozone pollution event occurring in winter (January) in Guangzhou. Various influencing factors were analyzed, including various atmospheric trace gases, meteorological conditions during the whole pollution process, as well as the characteristics of the main O3 precursor volatile organic compounds (VOCs). The main sources of VOCs and the O3 formation regime were analyzed using an array of tools:the ozone potential formation (OFP), positive matrix factorization (PMF) model, and empirical kinetic modeling approach (EKMA) curve. Feasible strategies for O3 control were suggested. The results showed that O3 and NO2 exceeded the corresponding standards in this winter pollution event, when the concentrations of PM10 and PM2.5 were also high, differing from the air pollution characteristics in summer and autumn. Low boundary layer height (<75 m) and high atmospheric stability at night exacerbated the accumulation of ozone precursors and fine particles. Meteorological conditions such as the increased daytime temperature (5℃), stronger solar radiation (10%), and low horizontal wind speed (<1 m·s-1) favored photochemical reactions and promoted the formation of ozone and fine particles. VOCs were mainly composed of alkanes, and the proportions of alkanes and alkynes in winter were higher than those in the other seasons. Aromatics (xylenes and toluene) and propylene were the key VOCs species leading to O3 formation. The main VOCs sources were vehicle exhaust (22.4%), solvent usage (20.5%), and industrial emissions (17.9%); however, the source with highest OFP was identified as solvent usage. O3 formation in this event was in the VOCs-limited regime, and reducing O3 precursors in the VOCs/NOx ratio of 3:1 was effective and feasible for O3 control. This study explored the causes of an O3 pollution event in winter, which will serve as reference for the synergistic control of O3 and PM2.5 in heavy pollution seasons.