scholarly journals Estimation of Surface Concentrations of Black Carbon from Long-Term Measurements at Aeronet Sites over Korea

2020 ◽  
Vol 12 (23) ◽  
pp. 3904
Author(s):  
Yongjoo Choi ◽  
Young Sung Ghim ◽  
Ying Zhang ◽  
Seung-Myung Park ◽  
In-ho Song
Keyword(s):  
Black Carbon ◽  
Measurement Data ◽  
Water Soluble ◽  
Mixing Rule ◽  
Range Transport ◽  
Urban Rural ◽  
Fine Mode ◽  
The Difference ◽  
Mlr Model

We estimated fine-mode black carbon (BC) concentrations at the surface using AERONET data from five AERONET sites in Korea, representing urban, rural, and background. We first obtained the columnar BC concentrations by separating the refractive index (RI) for fine-mode aerosols from AERONET data and minimizing the difference between separated RIs and calculated RIs using a mixing rule that can represent a real aerosol mixture (Maxwell Garnett for water-insoluble components and volume average for water-soluble components). Next, we acquired the surface BC concentrations by establishing a multiple linear regression (MLR) between in-situ BC concentrations from co-located or adjacent measurement sites, and columnar BC concentrations, by linearly adding meteorological parameters, month, and land-use type as the independent variables. The columnar BC concentrations estimated from AERONET data using a mixing rule well reproduced site-specific monthly variations of the in-situ measurement data, such as increases due to heating and/or biomass burning and long-range transport associated with prevailing westerlies in the spring and winter, and decreases due to wet scavenging in the summer. The MLR model exhibited a better correlation between measured and predicted BC concentrations than those based on columnar concentrations only, with a correlation coefficient of 0.64. The performance of our MLR model for BC was comparable to that reported in previous studies on the relationship between aerosol optical depth and particulate matter concentration in Korea. This study suggests that the MLR model with properly selected parameters is useful for estimating the surface BC concentration from AERONET data during the daytime, at sites where BC monitoring is not available.

scholarly journals Comparison of PM2.5 in Seoul, Korea Estimated from the Various Ground-Based and Satellite AOD

2021 ◽  
Vol 11 (22) ◽  
pp. 10755
Author(s):  
Sang-Min Kim ◽  
Ja-Ho Koo ◽  
Hana Lee ◽  
Jungbin Mok ◽  
Myungje Choi ◽  
...  
Keyword(s):  
Satellite Remote Sensing ◽  
Correlation Coefficients ◽  
Reasonable Accuracy ◽  
High Quality ◽  
Polar Orbit ◽  
Winter Condition ◽  
The Difference ◽  
Mlr Model

Based on multiple linear regression (MLR) models, we estimated the PM2.5 at Seoul using a number of aerosol optical depth (AOD) values obtained from ground-based and satellite remote sensing observations. To construct the MLR model, we consider various parameters related to the ambient meteorology and air quality. In general, all AOD values resulted in the high quality of PM2.5 estimation through the MLR method: mostly correlation coefficients >~0.8. Among various polar-orbit satellite AODs, AOD values from the MODIS measurement contribute to better PM2.5 estimation. We also found that the quality of estimated PM2.5 shows some seasonal variation; the estimated PM2.5 values consistently have the highest correlation with in situ PM2.5 in autumn, but are not well established in winter, probably due to the difficulty of AOD retrieval in the winter condition. MLR modeling using spectral AOD values from the ground-based measurements revealed that the accuracy of PM2.5 estimation does not depend on the selected wavelength. Although all AOD values used in this study resulted in a reasonable accuracy range of PM2.5 estimation, our analyses of the difference in estimated PM2.5 reveal the importance of utilizing the proper AOD for the best quality of PM2.5 estimation.

scholarly journals How Different Calculations of the Refractive Index Affect Estimates of the Radiative Forcing Efficiency of Ammonium Sulfate Aerosols

2011 ◽  
Vol 68 (9) ◽  
pp. 1845-1852 ◽  
Author(s):  
Carynelisa Erlick ◽  
Jonathan P. D. Abbatt ◽  
Yinon Rudich
Keyword(s):  
Refractive Index ◽  
Black Carbon ◽  
Ammonium Sulfate ◽  
Radiative Forcing ◽  
Radiative Properties ◽  
Refractive Indices ◽  
Mixing Rule ◽  
High Concentration ◽  
Aerosol Forcing ◽  
The Difference

Abstract Calculations of the radiative properties of hydrated ammonium sulfate (AS) aerosols often employ the conventional volume mixing rule, in which the refractive indices of AS and water are linearly averaged, weighted by their respective volume fractions in solution, and the real part of the refractive index of pure AS is taken to be 1.52–1.55, based on measurements of dry crystalline AS. However, there are significant differences between the refractive indices of AS–water solutions calculated using the conventional volume mixing rule and empirically derived refractive indices. The authors use a simple model for calculating the direct solar radiative forcing efficiency (RFE; radiative forcing divided by optical depth) of an optically thin layer of aerosols to investigate the magnitude of these differences. The difference between the conventional volume mixing rule and empirically derived refractive indices amounts to a modest difference in the direct solar RFE of AS aerosols at the top of the atmosphere at 0.550-μm wavelength and at relative humidities of 37%–99.9%. Without black carbon, the difference in RFE is up to −0.42 W m−2 for relative humidities less than around 66% and up to 0.25 W m−2 for relative humidities greater than 66%, whereas with 2% black carbon by volume, the range of difference in RFE is up to −0.59 W m−2 for relative humidities less than 66% and up to 0.30 W m−2 for relative humidities greater than 66%. Although modest, this difference in RFE may become important when investigating regional aerosol forcing in areas with a high concentration of urban and industrial pollution.

scholarly journals Atmospheric OH reactivity in central London: observations, model predictions and estimates of in situ ozone production

2016 ◽  
Vol 16 (4) ◽  
pp. 2109-2122 ◽  
Author(s):  
Lisa K. Whalley ◽  
Daniel Stone ◽  
Brian Bandy ◽  
Rachel Dunmore ◽  
Jacqueline F. Hamilton ◽  
...  
Keyword(s):  
Degradation Mechanism ◽  
Measurement Data ◽  
Oxidation Products ◽  
Chemical Mechanism ◽  
Ozone Production ◽  
Two Dimensional ◽  
Data Set ◽  
Diurnal Profile ◽  
The Difference

Abstract. Near-continuous measurements of hydroxyl radical (OH) reactivity in the urban background atmosphere of central London during the summer of 2012 are presented. OH reactivity behaviour is seen to be broadly dependent on air mass origin, with the highest reactivity and the most pronounced diurnal profile observed when air had passed over central London to the east, prior to measurement. Averaged over the entire observation period of 26 days, OH reactivity peaked at  ∼  27 s−1 in the morning, with a minimum of  ∼  15 s−1 during the afternoon. A maximum OH reactivity of 116 s−1 was recorded on one day during morning rush hour. A detailed box model using the Master Chemical Mechanism was used to calculate OH reactivity, and was constrained with an extended measurement data set of volatile organic compounds (VOCs) derived from a gas chromatography flame ionisation detector (GC-FID) and a two-dimensional GC instrument which included heavier molecular weight (up to C12) aliphatic VOCs, oxygenated VOCs and the biogenic VOCs α-pinene and limonene. Comparison was made between observed OH reactivity and modelled OH reactivity using (i) a standard suite of VOC measurements (C2–C8 hydrocarbons and a small selection of oxygenated VOCs) and (ii) a more comprehensive inventory including species up to C12. Modelled reactivities were lower than those measured (by 33 %) when only the reactivity of the standard VOC suite was considered. The difference between measured and modelled reactivity was improved, to within 15 %, if the reactivity of the higher VOCs (⩾ C9) was also considered, with the reactivity of the biogenic compounds of α-pinene and limonene and their oxidation products almost entirely responsible for this improvement. Further improvements in the model's ability to reproduce OH reactivity (to within 6 %) could be achieved if the reactivity and degradation mechanism of unassigned two-dimensional GC peaks were estimated. Neglecting the contribution of the higher VOCs (⩾ C9) (particularly α-pinene and limonene) and model-generated intermediates increases the modelled OH concentrations by 41 %, and the magnitude of in situ ozone production calculated from the production of RO2 was significantly lower (60 %). This work highlights that any future ozone abatement strategies should consider the role that biogenic emissions play alongside anthropogenic emissions in influencing London's air quality.

Functional Poly(p-Xylylene)s via Chemical Reduction of Poly(p-Phenylene Vinylene)s

2019 ◽  
Author(s):  
Ain Uddin ◽  
Weifan Sang ◽  
Yong Gao ◽  
Kyle Plunkett
Keyword(s):  
Film Formation ◽  
Chemical Reduction ◽  
Water Soluble ◽  
Phenylene Vinylene ◽  
Polymer Modification ◽  
Polymer Backbone ◽  
Crosslinking Process ◽  
Conducting Membranes ◽  
In Situ Crosslinking

The synthesis of poly(p-xylylene)s (PPXs) with sidechains containing alkyl bromide functionality, and their post-polymer modification, is described. The PPXs were prepared by a diimide hydrogenation of poly(p-phenylene vinylene)s (PPVs) that were originally synthesized by a Gilch polymerization. The polymer backbone reduction was carried out with hydrazine hydrate in toluene at 80 °C to provide polymers with the sidechain-containing bromide functionality intact. To demonstrate post-polymer modification of the sidechains, the resulting PPX polymers were modified with trimethylamine to form tetraalkylammonium ion functionality and were evaluated as anion conducting membranes. While PPX homopolymers containing tetralkylammonium ions were completely water soluble and not able to form valuable films, PPX copolymers containing mixed tetraalkylammonium ions and hydrophobic chains were capable of film formation and alkaline stability. In addition, an in situ crosslinking process that used N,N,N',N'-tetramethyl-1,6-hexanediamine during the tetraalkylammonium formation of brominated PPX polymers was also evaluated and gave reasonable films with conductivities of ~10 mS-cm-1.

Functional Poly(p-Xylylene)s via Chemical Reduction of Poly(p-Phenylene Vinylene)s

2019 ◽  
Author(s):  
Ain Uddin ◽  
Weifan Sang ◽  
Yong Gao ◽  
Kyle Plunkett
Keyword(s):  
Film Formation ◽  
Chemical Reduction ◽  
Water Soluble ◽  
Phenylene Vinylene ◽  
Polymer Modification ◽  
Polymer Backbone ◽  
Crosslinking Process ◽  
Conducting Membranes ◽  
In Situ Crosslinking

The synthesis of poly(p-xylylene)s (PPXs) with sidechains containing alkyl bromide functionality, and their post-polymer modification, is described. The PPXs were prepared by a diimide hydrogenation of poly(p-phenylene vinylene)s (PPVs) that were originally synthesized by a Gilch polymerization. The polymer backbone reduction was carried out with hydrazine hydrate in toluene at 80 °C to provide polymers with the sidechain-containing bromide functionality intact. To demonstrate post-polymer modification of the sidechains, the resulting PPX polymers were modified with trimethylamine to form tetraalkylammonium ion functionality and were evaluated as anion conducting membranes. While PPX homopolymers containing tetralkylammonium ions were completely water soluble and not able to form valuable films, PPX copolymers containing mixed tetraalkylammonium ions and hydrophobic chains were capable of film formation and alkaline stability. In addition, an in situ crosslinking process that used N,N,N',N'-tetramethyl-1,6-hexanediamine during the tetraalkylammonium formation of brominated PPX polymers was also evaluated and gave reasonable films with conductivities of ~10 mS-cm-1.

ANALISA KANDUNGAN BETA-GLUKAN LARUT AIR DAN LARUT ALKALI DARI TUBUH BUAH JAMUR TIRAM (Pleurotus ostreatus) DAN SHIITAKE (Lentinus edodes)

2013 ◽  
Vol 13 (3) ◽  
Author(s):  
Netty Widyastuti ◽  
Teguh Baruji ◽  
Henky Isnawan ◽  
Priyo Wahyudi ◽  
Donowati Donowati
Keyword(s):  
Molecular Structure ◽  
Molecular Weight ◽  
Immune System ◽  
Pleurotus Ostreatus ◽  
Water Soluble ◽  
Low Molecular Weight ◽  
Lentinus Edodes ◽  
Beta Glucan ◽  
Oyster Mushrooms ◽  
The Difference

Beta glucan is a polysaccharide compound, generally not soluble inwater and resistant to acid. Beta glucan is used as an immunomodulator (enhancing the immune system) in mammals is usually a beta-glucan soluble in water, easily absorbed and has a low molecular weight. Several example of beta-glucan such as cellulose (β-1 ,4-glucan), lentinan (β-1 0.6-glucan) and (β-1 ,3-glucan), pleuran (β-1, 6 and β-1 ,3-glucan) are isolated from species of fungi Basidiomycota include mushrooms (Pleurotus ostreatus) and shiitake (Lentinus edodes).The purpose of thisresearch activity is to obtain beta-glucan compound that can be dissolved in water and in alkali derived from fungi Basidiomycota, i.e, Oyster mushrooms (Pleurotus ostreatus) and shiitake (Lentinus edodes). The result of beta-glucan compared to characterize the resulting beta glucan that is molecular structure . The difference of beta glucan extraction is based on the differences in solubility of beta-glucan. Beta glucan could be water soluble and insoluble water.

Comparison of Mammography and Ultrasonography for Tumor Size of DCIS of Breast Cancer

2019 ◽  
Vol 15 (2) ◽  
pp. 209-213
Author(s):  
Yu Wang ◽  
Jiantao Wang ◽  
Haiping Wang ◽  
Xinyu Yang ◽  
Liming Chang ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Correlation Coefficient ◽  
Tumor Size ◽  
Ductal Carcinoma ◽  
Pearson Correlation ◽  
Dense Breast ◽  
Pathological Examination ◽  
Negative Group ◽  
The Difference

Objective: Accurate assessment of breast tumor size preoperatively is important for the initial decision-making in surgical approach. Therefore, we aimed to compare efficacy of mammography and ultrasonography in ductal carcinoma in situ (DCIS) of breast cancer. Methods: Preoperative mammography and ultrasonography were performed on 104 women with DCIS of breast cancer. We compared the accuracy of each of the imaging modalities with pathological size by Pearson correlation. For each modality, it was considered concordant if the difference between imaging assessment and pathological measurement is less than 0.5cm. Results: At pathological examination tumor size ranged from 0.4cm to 7.2cm in largest diameter. For mammographically determined size versus pathological size, correlation coefficient of r was 0.786 and for ultrasonography it was 0.651. Grouped by breast composition, in almost entirely fatty and scattered areas of fibroglandular dense breast, correlation coefficient of r was 0.790 for mammography and 0.678 for ultrasonography; in heterogeneously dense and extremely dense breast, correlation coefficient of r was 0.770 for mammography and 0.548 for ultrasonography. In microcalcification positive group, coeffient of r was 0.772 for mammography and 0.570 for ultrasonography. In microcalcification negative group, coeffient of r was 0.806 for mammography and 0.783 for ultrasonography. Conclusion: Mammography was more accurate than ultrasonography in measuring the largest cancer diameter in DCIS of breast cancer. The correlation coefficient improved in the group of almost entirely fatty/ scattered areas of fibroglandular dense breast or in microcalcification negative group.

scholarly journals A thin, deformable, high-performance supercapacitor implant that can be biodegraded and bioabsorbed within an animal body

2021 ◽  
Vol 7 (2) ◽  
pp. eabe3097
Author(s):  
Hongwei Sheng ◽  
Jingjing Zhou ◽  
Bo Li ◽  
Yuhang He ◽  
Xuetao Zhang ◽  
...  
Keyword(s):  
High Performance ◽  
Electronic Devices ◽  
Form Factors ◽  
Time Frame ◽  
Water Soluble ◽  
Two Dimensional ◽  
Medical Electronics ◽  
Thin Structure ◽  
Shed Light

It has been an outstanding challenge to achieve implantable energy modules that are mechanically soft (compatible with soft organs and tissues), have compact form factors, and are biodegradable (present for a desired time frame to power biodegradable, implantable medical electronics). Here, we present a fully biodegradable and bioabsorbable high-performance supercapacitor implant, which is lightweight and has a thin structure, mechanical flexibility, tunable degradation duration, and biocompatibility. The supercapacitor with a high areal capacitance (112.5 mF cm−2 at 1 mA cm−2) and energy density (15.64 μWh cm−2) uses two-dimensional, amorphous molybdenum oxide (MoOx) flakes as electrodes, which are grown in situ on water-soluble Mo foil using a green electrochemical strategy. Biodegradation behaviors and biocompatibility of the associated materials and the supercapacitor implant are systematically studied. Demonstrations of a supercapacitor implant that powers several electronic devices and that is completely degraded after implantation and absorbed in rat body shed light on its potential uses.

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