Roll-to-Roll Production of Electrocatalysts Achieving High-Current Alkaline Water Splitting.

Scalable production of electrocatalysts capable of performing high-current water splitting is crucial to support green energy utilization. We adopted acidic redox-assisted deposition (ARD) to realize the continuous roll-to-roll fabrication of a strongly adherent cobalt manganese oxyhydroxide (CMOH) film on Ni foam under ambient conditions in water. The as-fabricated products show uniform CMOH coverage and oxygen evolution activities with dimensions as large as 5 m length by 0.25 m width. Also, we converted CMOH into a metallic form (denoted as CM) with the preserved high adhesion to serve as a high-current hydrogen evolution electrocatalyst. Our results reveal that the insufficient adhesion of powder forms electrocatalysts (i.e., Pt and RuO2 as benchmarks), even with the binder, at high-current electrolysis (>1000 mA) can be solved using the fabricated CM||CMOH cell. With an active area of 1 cm × 1 cm assembly in anion exchange membrane (AEM) electrolyzers, we observed the remarkable record of alkaline electrolysis stably at 5000 mA. This result established a new benchmark record on the high-current water splitting research.

[Source Apportionment of Ambient Carbonyl Compounds Based on a PMF and Source Tracer Ratio Method: A Case Based on Observations in Nanjing].

Ambient carbonyl compounds play an important role in tropospheric atmospheric chemistry. Primary emissions and photochemical formation are both sources of carbonyls, and therefore it is challenging work to analyze their sources. In this study, carbonyl sources were apportioned using the source tracer ratio method (STR) and positive matrix factorization model (PMF) based on offline carbonyls observations at a site in Nanjing during March 2017. Eleven carbonyl compounds were detected, and their total concentrations were in the range of 2.57×10-9-22.83×10-9. Formaldehyde, acetaldehyde, and acetone were the main components, accounting for 36.8%, 21.6%, and 18.5% of the average concentration of eleven carbonyl compounds, respectively. The influences of tracer selection and background concentrations on the results of source apportionment using the STR method based on comparing the results of acetylene and toluene as tracers and the 5th and 10th percentages as background concentrations are presented. Five sources were resolved by PMF, including traffic emission, the petrochemical & chemical industry, paint & solvent use, secondary formation & background, and the chemical industry. Secondary formation & background sources were the largest contributors of carbonyl compounds, contributing 56.4%, 48.2%, and 58.3% to formaldehyde, acetaldehyde, and acetone, respectively. By comparing the carbonyl source apportionment results by STR and PMF, it was found that the STR depends on the selection of tracers. When the STR is applied in the areas with complex sources, it is difficult to use a tracer to indicate anthropogenic source emissions, and therefore it is not a suitable method for carbonyl source apportionment.

[Ratios of Volatile Organic Compounds in Ambient Air of Various Cities of China].

Volatile organic compounds (VOC) ratios in urban atmosphere could provide important information on VOC data quality, sources, and options for removal processes. Based on seven VOC measurement datasets, useful VOC ratios were calculated using four methods, including orthogonal distance(ODR), linear regression, geometric mean, mean, and frequency distribution. Ambient levels of m,p-xylene and o-xylene from the seven datasets showed good correlation with r ranging from 0.975 to 0.997, and their ratios (m,p-xylene/o-xylene) were close, with values of 2.78-3.05, indicating therefore that the ratio of m,p-xylene/o-xylene could be used to evaluate the quality of ambient measurement data in urban atmospheres. In addition, ratios of toluene versus benzene (T/B) and propane versus ethane (P/E) in different cities were compared, to investigate VOC sources in China. The highest T/B ratios were found in Shanghai and Guangzhou City, with values of 2.37 and 1.78, respectively, higher than the result from a tunnel study (1.52), suggesting the important influence of paint and solvent use. The T/B value for Beijing City during summer was close to that from the tunnel study, while the T/B ratios for Chengdu, Beijing during winter, and Chongqing were lower, with values ranging from 0.744 to 1.36, suggesting possible influences from biomass burning and coal combustion. The P/E value in Guangzhou was 1.27, significantly higher than the range of 0.270 to 0.645 found in other cities. The OH exposure in different cities were calculated based on o-xylene/ethylbenzene (X/E), with values ranging from 2.70×1010 to 4.45×1010 molecule·cm-3·s.

[VOCs Characteristics and Sources Apportionment in Yixing City During the G20 Summit].

A continuous measurement was conducted in Yixing city urban area from 24th August to 15th September using TH-300B continuous online GC-MS instrument during G20 summit in Hangzhou, 2016. The VOCs average mass concentrations of alkane, alkene, aromatic, acetylene, haloalkane hydrocarbons, OVOC and acetonitrile were 11.00×10-9, 1.93×10-9, 5.78×10-9, 1.23×10-9, 4.16×10-9, 10.37×10-9, 0.27×10-9, respectively. The photochemical reaction activity was calculated by using the maximum potential coefficient of Ozone Formation Potential. Alkene and aromatic hydrocarbons were the most active components of OFP. By applying the positive matrix factorization(PMF)model, five major factors were extracted to identify the sources of NMHCs in Yixing city, including industry(42.2%),vehicle exhaust(17.9%), fuel evaporation(20.8%), paint/solvent usage(7.0%)and plant(12.1%). Combined with the conditional probability function(CPF) analysis, source of anthropogenic pollution was related to the distribution of industrial enterprises in the northwest and southeast, while the plant source was related to the forest hilly region of Southwest Yixing city. The effect of air pollutant emission reduction showed that the primary emission air pollutants had declined significantly during the strict control period from 1th to 6th September in G20 summit,2016, and the industry proportion was reduced to 30.5%, whereas the plant proportion increased to 16.8%.

[Correlation Analysis Between Characteristics of VOCs and Ozone Formation Potential in Summer in Nanjing Urban District].

Volatile organic compounds (VOCs) is an important precursor of photochemical ozone pollution (O3) in the atmosphere. Their concentration variation directly affects the characteristics of the ozone pollution. The concentration, speciation of VOCs, ozone and its precursors in Nanjing were analyzed and measured using online gas detection systems in August 2013. VOCs/NOx discriminant method was used to get the sensitive control factors of ozone. The results showed that the averaged volume fraction of VOCs was 52. 05 x 10(-9), and the largest one reached 200 x 10(-9) in Nanjing urban district. The order of volume fraction of each species VOCs was alkane > oxygen-containing VOCs > alkene > aromatics. The averaged concentration of ozone was 76.5 microg x m(-1) and the exceeding concentration of hourly standard was 5.9%. The change trends of ozone precursors VOCs and NOx were basically identical and Ozone showed the obvious negative correlation during the period of high concentrations of ozone. There were some differences in the concentrations of the same VOCs in different ozone concentration periods. The ozone generation in Nanjing urban district was sensitive to VOCs, and Nanjing belonged to VOCs control area in summer.

Autonomous detection of pulmonary nodules on CT images with a neural network-based fuzzy system.

In this paper, a novel extension of neural network-based fuzzy model has been proposed to detect lung nodules. The proposed model can automatically identify a set of appropriate fuzzy inference rules, and refine the membership functions through the steepest gradient descent-learning algorithm. Twenty-nine clinical cases involving 583 thick section CT images were tested in this study. Receiver operating characteristic (ROC) analysis was used to evaluate the proposed autonomous pulmonary nodules detection system and yielded an area under the ROC curve of Azs=0.963. The overall detection sensitivity of the proposed method was 89.3% (with p-value less than 0.001), and the false positive was as low as 0.2 per image. This result demonstrates that the proposed neural network-based fuzzy system resolves the most suitable fuzzy rules, improves the detection rate, and reduces false positives compared to other approaches. The proposed system is fully automated with fast processing speed. The studies have shown a high potential for implementation of this system in clinical practice as a CAD tool.

[Spatial and temporal variations of ambient carbonyl compounds in Beijing and its surrounding areas].

Concentrations of 23 carbonyl compounds were measured by DNPH/HPLC method at 38 sites within Beijing and its surrounding areas on June 24, July 22, August 22, September 14 in 2010 and January 13, 2011. The average mixing ratios of total carbonyl compounds in Beijing were (16.38 +/- 6.03) x 10(-9) and (8.50 +/- 5.27) x 10(-9) in summer and winter; and the average mixing ratios in surrounding cites were (13.19 +/- 5.71) x 10(-9) and (13.05 +/- 2.44) x 10(-9) in summer and winter, respectively. The most abundant carbonyl compound was formaldehyde, followed by acetaldehyde and acetone, the sum of these 3 species accounted for 78% to 91% of the total mixing ratio of carbonyl compounds. The average mixing ratio in summer was significant higher than that in winter, and higher in morning (09:00-12:00) hours than in afternoon (13:00-16:00). The spatial distributions for carbonyl compounds showed that: in summer, high mixing ratios were typically found in city center; while in winter, a building-up trend was found from northwest to southeast, driving by the prevailing northwest wind. In summer, vehicular exhaust had important contributions to ambient carbonyls, and combined with the adverse weather conditions and the strong photochemical production, resulted in carbonyls pollutions; in winter, directly emissions were the main sources of carbonyls, such as vehicular exhaust and coal burning.