Enhanced nitrogen removal via partial nitrification/denitrification coupled Anammox using three stage anoxic/oxic biofilm process with intermittent aeration.

Pre-capturing organics in municipal wastewater for biogas production, combined with Anammox-based nitrogen removal process, improves the sustainability of sewage treatment. Thus, enhancing nitrogen removal via Anammox in mainstream wastewater treatment becomes very crucial. In present study, a three-stage anoxic/oxic (AO) biofilm process with intermittent aeration was designed to strengthen partial nitrification/denitrification coupling Anammox (PNA/PDA) in treatment of low C/N wastewater, which contained chemical oxygen demand (COD) of 79.8 mg/L and total inorganic nitrogen (TIN) of 58.9 mg/L. With a hydraulic retention time of 8.0 h, the process successfully reduced TIN to 10.6 mg/L, achieving a nitrogen removal efficiency of 83.3 %. The 1st anoxic zone accounted for 32.0 % TIN removal, with 10.3 % by denitrification and 21.7 % by PDA, meanwhile, the 2nd and 3rd anoxic zones contributed 19.4 % and 4.5 % of TIN removal, primarily achieved through PDA (including endogenous PD coupling Anammox). The 1st and 2nd intermittent zones accounted for 27.2 % and 17.0 % of TIN removal, respectively, with 13.7 %-21.3 % by PNA and 3.2 %-5.3 % by PDA. Although this process did not pursue nitrite accumulation in any zone (< 1.5 mg-N/L), PNA and PDA accounted for 35.1 % and 52.1 % of TIN removal, respectively. Only 0.21 % of removed TIN was released as nitrous oxide. The AnAOB of Candidatus Brocadia was enriched in each zone, with a relative abundance of 0.66 %-2.29 %. In intermittent zones, NOB had been partially suppressed (AOB/NOB = 0.73-0.88), mainly due to intermittent aeration and effective nitrite utilization by AnAOB since its population size was much greater than NOB. Present study indicated that the three-stage AO biofilm process with intermittent aeration could enhance nitrogen removal via PNA and PDA with a low N2O emission factor.

Detecting prokaryote-specific gene and other bacterial signatures in thrombi from patients with acute ischemic stroke.

BACKGROUND AND PURPOSE: Microbial infection has been associated with thrombogenesis. This study aimed to detect bacterium-specific genes and other signatures in thrombi from patients with acute ischemic stroke and to relate these signatures to clinical characteristics. METHODS: Blood samples were collected before thrombectomy procedures, and thrombus samples were obtained during the procedure. Identification and classification of bacteria in the samples were accomplished using 16 S rRNA gene sequencing. Bacterium-specific structures were observed with transmission electron microscopy. Bacterium-specific biomarkers were detected through immunohistochemical staining. RESULTS: 16 S rRNA gene was detected in 32.1% of the thrombus samples from 81 patients. Bacillus (0.04% vs. 0.00046%, p = 0.003), Parabacteroides (0.20% vs. 0.09%, p = 0.029), Prevotella (1.57% vs. 0.38%, p = 0.010), Streptococcus (1.53% vs. 0.29%, p = 0.001), Romboutsia (0.18% vs. 0.0070%, p = 0.029), Corynebacterium (1.61% vs. 1.26%, p = 0.026) and Roseburia (0.53% vs. 0.05%, p = 0.005) exhibited significantly higher abundance in thrombi compared to arterial blood. Bacteria-like structures were observed in 22 (27.1%), while whole bacteria-like structures were observed in 7 (8.6%) thrombi under transmission electron microscopy. Immunohistochemical staining detected bacterium-specific monocyte/macrophage markers in 51 (63.0%) out of 81 thrombi. Logistic regression analysis indicated that alcohol consumption was associated with a higher bacteria burden in thrombi (odds ratio = 3.19; 95% CI, 1.10-9.27; p = 0.033). CONCLUSION: Bacterial signatures usually found in the oral cavity and digestive tract were detected in thrombi from patients with ischemic stroke. This suggests a potential involvement of bacterial infection in the development of thrombosis. Long-term alcohol consumption may potentially enhance this possibility.

Dietary Flavonoid Intake and Carotid Calcification in Patients with Ischemic Stroke.

INTRODUCTION: Owing to the antioxidant and anti-inflammatory effects, flavonoids can influence the initiation and development of atherosclerosis, but the underlying mechanisms remain largely undetermined. This study aimed to evaluate the associations between dietary flavonoids and carotid calcification in patients with ischemic stroke. METHODS: This study screened consecutive patients with ischemic stroke via Nanjing Stroke Registry Program from February 2016 to April 2021. A semiquantitative food frequency questionnaire was used to evaluate dietary consumption of flavonoids and other nutritional components. Presence and degree of carotid calcification were determined according to Agatston scores on computer tomography angiography. Logistic regression was performed to evaluate the association between dietary flavonoids (total flavonoids, flavonols, flavones, flavanones, flavan-3-ols, anthocyanins, and isoflavones) and carotid calcification. RESULTS: Of the 601 enrolled patients, 368 (61.2%) were detected with carotid calcification. Patients with high intake of total flavonoids (the fifth quintile) had a 52% lower carotid calcification risk than those with low intake (the first quintile; odds ratio [OR] = 0.48; 95% confidence interval [CI], 0.26-0.90; p = 0.007 for trends) after adjusting for major confounders. Patients with high intake of flavan-3-ols (the fifth quintile) had a 51% lower carotid calcification risk than those with low intake (the first quintile; OR = 0.49; 95% CI, 0.25-0.97; p = 0.016 for trends). CONCLUSION: Dietary flavonoid intake is associated with carotid calcification, and, therefore, may influence the risk of stroke occurrence and recurrence.

Association between dietary antioxidant capacity and atherosclerotic carotid stenosis in patients with ischemic stroke.

BACKGROUND AND PURPOSE: The aim of this study was to evaluate the relationship between dietary total antioxidant capacity (DTAC) and atherosclerotic carotid stenosis in patients with ischemic stroke. METHODS: Patients with acute ischemic stroke were consecutively enrolled. Daily food consumption was estimated by a semi-quantitative food frequency questionnaire (FFQ). DTAC was calculated based on classified food intake. Antioxidant potential value was measured by ferric-reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) methods. Evaluation of carotid artery stenosis was based on computed tomography angiography (CTA). Logistic regression was used to assess the relationship between DTAC and degree of carotid stenosis. RESULTS: Of the 608 enrolled, 232 patients (38.2%) had moderate or severe carotid stenosis. After adjusting for major confounding factors, FRAP (OR =0.640; 95% CI: 0.410-0.998; P =0.049) and ORAC (OR =0.625; 95% CI: 0.400-0.976; P =0.039) were associated with lower degree of carotid artery stenosis (third vs first tertile). Spearman analysis indicated that FRAP (r =-0.121, P =0.003) and ORAC (r =-0.147, P <0.001) were correlated with degree of carotid stenosis. CONCLUSIONS: DTAC may influence the initiation and development of atherosclerosis, and, therefore, the risk of ischemic stroke.

Quality control of Hugan capsule based on four-wavelength fusion profiling and electrochemical fingerprint combined with antioxidant activity and chemometric analysis.

Improving the quality standard system of herbal preparations (HPs) is an arduous task for the development of traditional Chinese medicine (TCM). At present, an urgent task is to establish a comprehensive, scientific and effective evaluation method for improving the safety, effectiveness and quality consistency of HPs. In this study, Hu Gan capsules (HGCs) were used as an example. Firstly, the three quality markers (Q-markers) in 21 batches of HGCs from 4 manufacturers were determined by HPLC and great difference in content of each sample was found. Furthermore, four-wavelength fusion profiling (FWFP) was established and evaluated by systematically quantified fingerprint method (SQFM). Principal component analysis (PCA) was employed to make a preliminary analysis of the FWFP and distinguish the fluctuation of differences in chemical composition and content. Then, 9 characteristic parameters were recorded through the B-Z oscillating system, and the electrochemical fingerprint (ECFP) was constructed for jointing evaluation with the FWFP, using the equal weight of SQFM results to comprehensively evaluate the sample quality. The 21 batches of samples were divided into four groups and six grades, which indicated that there were significant differences in the content of indicator components and electrochemical active substances in samples. Finally, taking vitamin C as a positive control, 2, 2'-azino-bis (3 - ethyl -benzthiazoline - 6 - sulfonic acid) (ABTS) scavenging assay was applied to study the antioxidant activity of samples. Partial Least Squares (PLS) and bivariate correlation analysis (BCA) were used to analyze the fingerprint-efficacy relationships of FWFP-ABTS and FWFP-ECFP. Consequently, it was found that there were similar antioxidant capacities in electrochemistry and ABTS tests, and 31 of the 40 HPLC fingerprint peaks of HGCs were discovered to have antioxidant activity. The two methods supported each other, to effectively and corporately reflect the antioxidant components in HGCs. In this research, the FWFP and ECFP established could realize the quality detection of HGCs, and provide a novel direction for the improvement of the quality standard of HPs and the research of the quality standard method of TCM.

Polarization reflection distribution characteristics of wakes on the sea surface.

Research on the polarization reflection distribution characteristics of wakes on the sea surface can provide a theoretical basis for ocean wake target detection and has important research value in the field of ship and underwater moving target monitoring. The Kelvin wake model and the Cox-Munk model are used to describe a wake on a rough sea surface. Considering the atmospheric Rayleigh scattering and the reflection characteristics of a rough sea surface, a visible spectrum band wake polarization characteristic model based on the Stokes vector and Mueller matrix is established to explore the polarization reflection distribution characteristics of wakes on the sea surface under skylight background at different wind speeds, wind directions, and sun angles. A simulation is done of the airborne polarization reflection imaging of wakes on a rough sea surface. The results show that under the determined observation angle, the polarization distribution characteristics of wakes on a rough sea surface are mainly related to the angle of the sun. The polarization contrast of simulated wakes in typical scenes is acceptable, and it is feasible to detect sea wake targets by the polarization method. The analysis and simulation of the wake polarization characteristics model can provide a theoretical basis for ocean wake target detection.

Detection of microalgae objects based on the Improved YOLOv3 model.

Microalgae play a major role in the invasion of alien organisms with ballast water as a carrier, and traditional ballast water detection methods have many limitations in identifying microalgae species. Therefore, this paper proposes a method to identify microalgae in ballast water based on an Improved YOLOv3 model. The method first used a lightweight network MobileNet instead of the Darknet-53 network as the backbone network of feature extraction in the original YOLOv3 model. Secondly, improved spatial pyramid pooling (SPP) is introduced to pool and concatenate the multi-scale regional features so as to reduce the position error when detecting small objects. Then, by considering the overlap area of the bounding box, central point distance and aspect ratio, the Complete IoU (CIoU) algorithm is used to optimize the loss function of the YOLOv3 model. Finally, the proposed method is experimentally compared with other latest methods on the established dataset. The experimental results demonstrated that under the same conditions, this Improved YOLOv3 model achieves an average accuracy of 98.90%, and the detection efficiency is 8.59% higher than that of the original YOLOv3 model and is better than the existing methods. The average time of this method to identify a single image is 0.086 s, and it has a good detection effect on the identification of microalgae species.

The evaluation of the chemical quality and UV overall components dissolution consistency of Flos Chrysanthemi Indici preparation.

In recent years, new chemical technology and chemical analysis methods have been widely used for the quality control of medicine to provide security for human life. However, for the increasingly popular traditional Chinese medicine (TCM) preparations, the traditional quality control technology has been challenged due the presence of multi-components. To solve this problem, this study proposed a comprehensive evaluation strategy from two aspects: chemical quality and in vitro dissolution consistency. Zhenju antihypertensive tablet (FCIP), as the research object of this study, is a compound preparation of Flos Chrysanthemi Indici with moderate antihypertensive effect. For the chemical quality, the capillary electrophoresis fingerprint (CE-FP) was established based on the characteristic multi-wavelength averaging fusion profiling (CMW-AFP) strategy, which can fuse peaks in the CE chromatogram at several select characteristic wavelengths into one profile through an averaging algorithm. All samples were clarified into 5 quality grades using the systematic quantified fingerprint method, and showed significant difference among the four manufacturers. Combined with the accurate determination of the marker components, the CE-FP evaluation results can provide a guarantee for the chemical quality consistency. For the in vitro dissolution consistency, a UV overall components dissolution method was proposed. Meanwhile, in order to match the established UV overall dissolution system, two f2 factors (f2-R and f2-MI) were calculated to compare the dissolution profiles. By comparing the chemical and UV overall dissolution results plus the PCA analysis, the holistic quality of the FCIP samples of four manufacturers were obtained as MA > MC > MD > MB. The established evaluation system is also a suitable strategy for controlling the chemical quality and dissolution consistency of other TCM preparations.

Fine-grained classification of fly species in the natural environment based on deep convolutional neural network.

Effective classification of flies is beneficial to prevent the spread of disease and protect agricultural production. It is important to prevent the invasion of fly species. Aiming at the problem of similar morphology and difficulty in the classification of fly species in the natural environment, this paper proposes a fine-grained classification method for fly species in the complex natural environment based on deep convolutional neural network. Firstly, the specific position of the fly in the image is located by the gradient-weighted class activation graph method, and the object region of the fly is obtained. Then, the local region containing the most abundant information in the image is extracted. When extracting features from the local region, the attention module and cross-layer bilinear pooling are combined. The feature information of different convolutional layers is integrated. Finally, the global and local feature information is integrated for classification. We experimentally compared the proposed method with other state-of-the-art methods on the established dataset. Experimental results show that the accuracy of the proposed method on the three datasets is 84.34%, 89.53% and 93.26%, respectively. Compared with other state-of-the-art methods, this method has a good classification effect on fly species.

[Expression of Ras-Associated Protein 1 in the Vascular Endothelium of Bone Tissue with Non-Traumatic Osteonecrosis of Femoral Head].

Objective: To investigate the difference in the expression of Ras-associated protein 1 (Rap1) in necrotic and healthy areas of non-traumatic osteonecrosis of femoral head (NONFH) patients. Methods: Femoral head tissue samples from 30 cases of NONFH and 30 cases of traumatic osteonecrosis of the femoral head (TONFH) were collected after hip replacement surgery, respectively. No significant difference of Association Research Circulation Osseous (ARCO) staging was found between the NONFH and the TONFH groups ( Z=-0.769, P=0.442). In the NONFH group, 8 patients were ARCO stage IIIb, 10 were stage IV, and 12 were stage V, while in the TONFH ground, 11 patients were ARCO stage IIIb, 9 were stage IV, and 10 were stage V. There were 19 males and 11 females in the NONFH group, with an average age of 49.6 yr. (26-69 yr.), and 16 males and 14 females in the TONFH group, with an average age of 54.2 yr. (37-68 yr.). There was no significant difference in gender or age between the two groups ( P>0.05). Specimens were collected from different bone areas, including those from the necrotic areas (area A) and the healthy areas (area B) of the NONFH group, and those from the healthy areas (area B') of the TONFH group, i.e., the control group. Western blot and quantitative real-time reverse transcription PCR (qRT-PCR) were used to analyze the different expression of Rap1, vascular endothelial growth factor (VEGF) protein, phosphoinositide 3-kinase (PI3K), and Akt protein and their corresponding mRNA in the three areas of bone tissue. HE staining and immunohistochemisty staining were done in order to observe the morphological changes of each area. Results: Western blot results indicated that there was no statistical difference in the relative expression of Rap1, VEGF, PI3K, and Akt proteins ( P>0.05). The relative expressions of Rap1, VEGF, PI3K, and Akt proteins in the area A were lower than those in the area B and the difference was statistically significant ( P<0.05). qRT-PCR results showed that the relative expressions of Rap1, VEGF, PI3 K and Akt mRNA in area A were lower than those of area B, and a statistical difference was found ( P<0.05). The relative expression of the mRNA of Rap1, VEGF , PI3 K and Akt in area B and area B' were not significantly different ( P>0.05). HE staining and immunohistochemisty staining showed that chondrocytes decreased in the necrotic area (area A) of NONFH, chondrocytes nucleus disappeared, subchondral bone trabeculae were broken, bone trabeculae thickened, and empty bone lacunae appeared. Granulation tissues composed of new capillaries and fibrous cells have proliferated and crawled around the necrotic area. Positive expressions of the Rap1, VEGF, PI3K and Akt proteins in area A were weaker than those of the normal area. In addition, there were positive expressions of Rap1, PI3K and Akt on the trabecular bone of both area A and area B at similar intensity of expression. There were strong positive expressions of Rap1, VEGF, PI3K and Akt on the intima of arterioles and venules, and on the peripheral stromal cell membrane, but the positive expression in area A was significantly lower than that in area B. However, the positive expression positions and intensity of all indicators were similar in area B and area B'. Conclusion: The necrosis in NONFH may be related to vascular endothelial damages caused by the inhibition of the Rap1-PI3K/Akt signaling pathways and the subsequent decline in the protein expression.

[Aqueous-phase Oxidation of Dissolved Organic Matter (DOM) from Extracts of Ambient Aerosols].

Recently, a large number of laboratory studies have focused on the aqueous-phase photochemistry of single organic compound in atmospheric condensed phases, yet few studies have been conducted on the aqueous-phase photochemical oxidation of real-world complex dissolved organic matter (DOM). Therefore, in this work, we report experimental results for the photochemical oxidation of DOM extracts from ambient fine aerosol samples upon direct photolysis or against OH oxidation, under both simulated sunlight and ultraviolet irradiation conditions. The products at different stages of photolysis were analyzed via UV-vis and spectroscopy and soot-particle aerosol mass spectrometry (SP-AMS) to investigate their optical and chemical characteristics. The results demonstrate the effective degradation of DOM under UV irradiation, and the f44 values of the corresponding products aremuch lower than under sunlight irradiation. A variety of carboxylic acids were generated during liquid-phase photolysis, and oxalic acid was found to be the most abundant. The light absorbance and concentration of HULIS did not change significantly under sunlight illumination; however, under UV and UV+·OH conditions, the concentration of HULIS increased continuously with reaction time. The HULIS concentration at 23 h was approximately four times the initial value, indicating the formation of brown carbon species with carboxyl, hydroxyl, and aromatic and other functional groups. Our results show that the increase in light absorptivity and formation rate of brown carbon from DOM are limited when aqueous-phase oxidation occurs under sunlight illumination. In comparison, DOM can constantly decompose into HULIS or small molecules under ultraviolet light illumination, and the light absorptivity of the remaining organic matter may be relatively high, resulting in final products with a high unit mass absorption efficiency (MAE). We have investigated the aqueous-phase oxidation of actual filter extracts for the first time, and our results provide valuable insights to the formation of air pollution complexes.

[Analysis of Water Soluble Organic Aerosol in Spring PM2.5 with Soot Particle Aerosol Mass Spectrometry (SP-AMS)].

To investigate the chemical composition and pollution characteristics of spring fine particles (PM2.5) in Changzhou, a total of 84 PM2.5 samples were collected from March 1st to May 30th, 2017. We measured and analyzed conventional components, such as water-soluble ions (WSIIs) and carbonaceous components (OC and EC). The water-soluble organic aerosol (WSOA) was also analyzed by an aerodyne soot particle aerosol mass spectrometer (SP-AMS). During the sampling period, the average daily PM2.5 concentration was 101.97 µg·m-3, with more than 73.8% sampling days exceeding the Target-2 standard of the national ambient air quality standard of China. The air quality during the sampling period was dominated by light, moderate, and heavy pollution, accounting for 39.3%, 21.4%, and 13.1% of the total days, respectively. The total WSIIs accounted for 39.86% of PM2.5 mass, of which secondary ions (SO42-, NH4+, and NO3-) accounted for 81.85% of the total WSIIs. The slope of the linear fitted line of the anion and cation charge balance (AE/CE) was greater than 1 (1.09), which indicated that PM2.5 was weakly acidic. The average OC/EC ratio was 2.53, indicating that PM2.5 was influenced by the secondary conversion. WSOA included CxHy+(32.1%), CxHyO+(30.4%), CxHyO2+(25.4%), and HyO+(4.7%) identified by SP-AMS. The average oxygen-to-carbon (O/C), hydrogen-to-carbon (H/C), nitrogen-to-carbon (N/C), and organic matter-to-organic carbon (OM/OC) ratios of the WSOA were 0.72, 1.53, 0.04, and 2.15, respectively. Higher O/C indicated higher contributions from secondary photochemical reaction conversion in spring. Positive matrix factorization (PMF) analysis for AMS mass spectra of WSOA identified three sources, namely hydrocarbon-like (HOA), semi-volatile oxygenated OA (SVOOA)-biomass burning OA (BBOA), and low-volatility oxygenated OA (LVOOA), which on average accounted for 18.4%, 34.1%, and 47.4% of the total WSOA, respectively.

Secondary organic aerosol formation from 3C⁎-initiated oxidation of 4-ethylguaiacol in atmospheric aqueous-phase.

In this study, we investigated aqueous-phase triplet excited states (3C⁎)-induced photo-degradation of 4-ethylguaiacol (EG) under both simulated sunlight and ultraviolet (UV) light irradiations. Through quencher experiments, the relative contributions of reactive oxygen species (ROS, such as 1O2/O2-/·OH) and 3C⁎ were calculated and results showed three reactive species, e.g., 3C⁎, 1O2 and O2-, all seemed to play important roles in the photo-degradation of EG, but contribution from ·OH was relatively minor. High steady-state 1O2 concentration after 1 h irradiation further revealed the major contribution of 1O2 to photo-degradation under Xe light irradiation. The degradation experiment under three saturated gases (air, O2 and N2) showed that the degradation rate in air-saturated condition was the largest owing to synergistic effect of 1O2 and 3C⁎. Oxidative capacity of aqueous secondary organic aerosol (aqSOA) increased with reaction time by monitoring oxygen-to­carbon (O/C) ratio and carbon oxidation state (OSc) via an aerodyne soot particle aerosol mass spectrometer (SP-AMS). Moreover, aqSOA mass yields were calculated via SP-AMS data. The UV-vis spectral change suggested formation of light-absorbing organics at first stage under simulated sunlight irradiation. Based on the identified products and the reactive intermediates, we postulated that 3C⁎-induced oxidation might be attributed to direct reactions by 3C⁎ and 1O2, chemical reaction by ROS, as well as oligomerization via H-abstraction. To the best of our knowledge, this is the first time to explore systematically reaction pathways of 4-ethylguaiacol under 3C∗ radical on the basis of thorough analysis of products and reactive species. Our findings highlight the impacts of aqSOA from biomass burning emissions on air quality and climate change.

An End-to-End Oil-Spill Monitoring Method for Multisensory Satellite Images Based on Deep Semantic Segmentation.

In remote-sensing images, a detected oil-spill area is usually affected by spot noise and uneven intensity, which leads to poor segmentation of the oil-spill area. This paper introduced a deep semantic segmentation method that combined a deep-convolution neural network with the fully connected conditional random field to form an end-to-end connection. On the basis of Resnet, it first roughly segmented a multisource remote-sensing image as input by the deep convolutional neural network. Then, we used the Gaussian pairwise method and mean-field approximation. The conditional random field was established as the output of the recurrent neural network. The oil-spill area on the sea surface was monitored by the multisource remote-sensing image and was estimated by optical image. We experimentally compared the proposed method with other models on the dataset established by the multisensory satellite image. Results showed that the method improved classification accuracy and captured fine details of the oil-spill area. The mean intersection over the union was 82.1%, and the monitoring effect was obviously improved.

Characteristics, sources and health risks of toxic species (PCDD/Fs, PAHs and heavy metals) in PM2.5 during fall and winter in an industrial area.

Particulate toxic species, such as polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs), polycyclic aromatic hydrocarbons (PAHs) and heavy metals may have significant health risks. This study investigated characteristics, sources and health risks of all three classes of toxic species in PM2.5 (particles with aerodynamic diameter ≤2.5 µm) samples collected at an industrial area in Changzhou, a big city in the Yangtze Delta region of China. Fourteen heavy metals altogether constituted 2.87% of PM2.5 mass, with Fe, Al and Zn as the major elements. Principal component analysis (PCA) suggested that heavy metals came from four sources: vehicles, industry, crustal dust, mixed coal combustion and industrial process. The daily average concentration of 18 PAHs was 235.29 ng/m3, accounting for 0.21% of PM2.5 mass. The dominant PAHs were high molecular weight ones, contributing 73.5% to the total PAHs. Diagnostic analyses indicated that sources of PAHs included vehicle/coal combustion and petroleum emissions, wherein diesel emission played a more important role than gasoline emission. PCA showed that the largest contributor of PAHs was vehicle exhaust mixed with coal combustion, followed by three industry-related sources. Total concentration of 17 PCDD/Fs varied between 3.14 and 37.07 pg/m3, with an average of 14.58 pg/m3. The 10 PCDFs accounted for 70.5% of total concentration of 17 PCDD/Fs. Health risk assessments showed that the carcinogenic risk of heavy metals was acceptable, while risks from PAHs and PCDD/Fs cannot be ignored. Back trajectory analysis indicated that local/regional transported air masses from northern China was the major source areas of the toxic species.

[Secondary Organic Aerosol Mass Yield and Characteristics from 4-ethylguaiacol Aqueous·OH Oxidation: Effects of Initial Concentration].

Aqueous-phase chemical processing, as an essential formation pathway of secondary organic aerosol (SOA), has attracted widespread attention from within atmospheric chemistry fields. Due to the complicated reaction nature, reaction mechanisms, and product characteristics of aqueous-phase chemical processing, its contribution to the SOA budget is still not fully understood. In this work, we investigate how the initial concentration (0.03-3 mmol·L-1) of 4-ethylguaiacol affects SOA formation of aqueous·OH photochemical oxidation. We use soot-particle aerosol mass spectrometry (SP-AMS) to monitor SOA mass yield and oxidation character, and gas chromatography-mass spectrometry (GC-MS) and ion chromatography (IC) to measure products and organic acids. Additionally, we use ultraviolet visible spectroscopy (UV-vis) and high-performance liquid spectrometry (HPLS) to track the formation of light-absorbing products such as humic-like substances (HULIS). Our research indicated that the range of the O/C ratio of EG-aqSOA measured by the SP-AMS exhibited increasing trends with increased reaction time 0.42-0.61 (0.03 mmol·L-1), 0.49-0.84 (0.3 mmol·L-1), and 0.49-0.63 (3 mmol·L-1). Dimers (C16H18 O2+, m/z 302) via SP-AMS were obviously higher under a higher initial concentration, thereby demonstrating that the oligomerization reaction proceeded more easily. The absorption at 250 nm recorded by UV-vis was distinctly enhanced, which might be attributed to new light-absorbing products with absorbance at 250 nm. Furthermore, the HULIS concentration increased with reaction time, in accordance with enhancement of absorbance in the 300-400 nm region, thus suggesting that aqueous-phase processing formed brown carbon. Small organic acids, including formic acid, malic acid, and oxalic acid, were detected by IC in all reaction solutions, with the highest concentration being for formic acid. GC/MS detected ketone, an OH monomer, and dimers in the aqSOA, which further indicates that functionalization and oligomerization took place.

A comprehensive investigation of aqueous-phase photochemical oxidation of 4-ethylphenol.

Secondary organic aerosol (SOA) species formed in atmospheric aqueous phases is recently recognized as an important contributor to fine aerosols, which is known to be a prominent human health risk factor internationally. This work, for the first time, systematically investigated aqueous-phase photochemical oxidation of 4-ethylphenol (4-EP) - a model compound from biomass burning and a surrogate of intermediate volatility organic compounds, under both ultraviolet (UV) (Hg lamp) and simulated sunlight (Xe lamp). We found that 4-EP could degrade upon hydroxal radical (OH) oxidation under UV light nearly 15 times faster than that under simulated sunlight, but large aqueous SOA (aqSOA) yields (108%-122%) were observed under both situations. AqSOA masses and oxidation states continuously increased under simulated sunlight, yet they increased first then decreased quickly under UV light. We proposed a reaction scheme based on identified products, showing that oligomerization, functionalization and fragmentation all can occur during 4-EP oxidation. Our results demonstrate that OH radical may suppress oligomerization and functionalization, but is favorable for fragmentation. Under UV light with H2O2 (high OH), fragmentation was dominant, producing more volatile and smaller molecules, and less aqSOA in later oxidation; Under simulated sunlight with H2O2 (moderate OH), functionalization that can form hydroxylated monomer was more important. Moreover, 4-EP oxidation by the organic triplet excited state (3C*) could form species with stronger visible light absorptivity than those from OH-mediated oxidation, and the absorptivity showed positive link with contents of humic-like substances.

Thermal and Optical Modulation of the Carrier Mobility in OTFTs Based on an Azo-anthracene Liquid Crystal Organic Semiconductor.

One of the most striking features of organic semiconductors compared with their corresponding inorganic counterparts is their molecular diversity. The major challenge in organic semiconductor material technology is creating molecular structural motifs to develop multifunctional materials in order to achieve the desired functionalities yet to optimize the specific device performance. Azo-compounds, because of their special photoresponsive property, have attracted extensive interest in photonic and optoelectronic applications; if incorporated wisely in the organic semiconductor groups, they can be innovatively utilized in advanced smart electronic applications, where thermal and photo modulation is applied to tune the electronic properties. On the basis of this aspiration, a novel azo-functionalized liquid crystal semiconductor material, (E)-1-(4-(anthracen-2-yl)phenyl)-2-(4-(decyloxy)phenyl)diazene (APDPD), is designed and synthesized for application in organic thin-film transistors (OTFTs). The UV-vis spectra of APDPD exhibit reversible photoisomerizaton upon photoexcitation, and the thin films of APDPD show a long-range orientational order based on its liquid crystal phase. The performance of OTFTs based on this material as well as the effects of thermal treatment and UV-irradiation on mobility are investigated. The molecular structure, stability of the material, and morphology of the thin films are characterized by thermal gravimetric analysis (TGA), polarizing optical microscopy (POM), (differential scanning calorimetry (DSC), UV-vis spectroscopy, atomic force microscopy (AFM), and scanning tunneling microscopy (STM). This study reveals that our new material has the potential to be applied in optical sensors, memories, logic circuits, and functional switches.