scholarly journals Size-distributions of <i>n</i>-alkanes, PAHs and hopanes and their sources in the urban, mountain and marine atmospheres over East Asia

2009 ◽  
Vol 9 (22) ◽  
pp. 8869-8882 ◽  
Author(s):  
G. Wang ◽  
K. Kawamura ◽  
M. Xie ◽  
S. Hu ◽  
S. Gao ◽  
...  
Keyword(s):  
East Asia ◽  
Geometric Mean ◽  
Bimodal Distribution ◽  
Size Distributions ◽  
Marine Aerosols ◽  
Hygroscopic Growth ◽  
Okinawa Island ◽  
Marine Samples ◽  
Fine Mode ◽  
The Difference

Abstract. Size-segregated (9 stages) n-alkanes, polycyclic aromatic hydrocarbons (PAHs) and hopanes in the urban (Baoji city in inland China), mountain (Mt. Tai in east coastal China) and marine (Okinawa Island, Japan) atmospheres over East Asia were studied using a GC/MS technique. Ambient concentrations of n-alkanes (1698±568 ng m−3 in winter and 487±145 ng m−3 in spring), PAHs (536±80 and 161±39 ng m−3), and hopanes (65±24 and 20±2.4 ng m−3) in the urban air are 1–2 orders of magnitude higher than those in the mountain aerosols and 2–3 orders of magnitude higher than those in the marine samples. Mass ratios of n-alkanes, PAHs and hopanes clearly demonstrate coal-burning emissions as their major source. Size distributions of fossil fuel derived n-alkane, PAHs and hopanes were found to be unimodal in most cases, peaking at 0.7–1.1 μm size. In contrast, plant wax derived n-alkanes presented a bimodal distribution with two peaks at the sizes of 0.7–1.1 μm and >4.7 μm in the summer mountain and spring marine samples. Among the three types of samples, geometric mean diameter (GMD) of the organics in fine mode (<2.1 μm) was found to be smallest (av. 0.63 μm in spring) for the urban samples and largest (1.01 μm) for the marine samples, whereas the GMD in coarse mode (≥2.1 μm) was found to be smallest (3.48 μm) for the marine aerosols and largest (4.04 μm) for the urban aerosols. The fine mode GMDs of the urban and mountain samples were larger in winter than in spring and summer. Moreover, GMDs of 3- and 4-ring PAHs were larger than those of 5- and 6-ring PAHs in the three types of atmospheres. Such differences in GMDs can be interpreted by the repartitioning of organic compounds and the coagulation and hygroscopic growth of particles during a long-range transport from the inland continent to the marine area, as well as the difference in their sources among the three regions.

scholarly journals Size-distributions of <i>n</i>-hydrocarbons, PAHs and hopanes and their sources in the urban, mountain and marine atmospheres over East Asia

2009 ◽  
Vol 9 (3) ◽  
pp. 13859-13888
Author(s):  
G. Wang ◽  
K. Kawamura ◽  
M. Xie ◽  
S. Hu ◽  
S. Gao ◽  
...  
Keyword(s):  
East Asia ◽  
Climate Models ◽  
Geometric Mean ◽  
Organic Aerosols ◽  
Bimodal Distribution ◽  
Size Distributions ◽  
Marine Aerosols ◽  
Okinawa Island ◽  
Marine Samples ◽  
Fine Mode

Abstract. Size-segregated (9 stages) n-alkanes, polycyclic aromatic hydrocarbons (PAHs) and hopanes in the urban (Baoji city in inland China), mountain (Mt. Tai in east coastal China) and marine (Okinawa Island, Japan) atmospheres over East Asia were studied using a GC/MS technique. Concentrations of n-alkanes (1698±568 ng m−3 in winter and 487±145 ng m−3 in spring), PAHs (536±80 and 161±39 ng m−3), and hopanes (65±24 and 20±2.4 ng m−3) in the urban air are 1–2 orders of magnitude higher than those in the mountain aerosols and 2–3 orders of magnitude higher than those in the marine samples. Mass ratios of n-alkanes, PAHs and hopanes clearly demonstrate coal-burning emissions as the major source of the determined organic aerosols. Size distributions of fossil fuel derived n-alkane, PAHs and hopanes were found as a unimodal in most cases, peaking at 0.7–1.1 μm size. In contrast, plant wax derived n-alkanes present a bimodal distribution with two peaks at the sizes of 0.7–1.1 μm and >4.7 μm in the summer mountain and spring marine samples. Among the three types of samples, geometric mean diameter (GMD) of the determined organics in fine mode (<2.1 μm) was the smallest (av. 0.63 μm in spring) in the urban samples and the largest (1.01 μm) in the marine samples, whereas the GMD in coarse mode (≥2.1 μm) was smallest (3.48 μm) in the marine aerosols and largest (4.04 μm) in the urban aerosols. The fine mode of GMDs in the urban and mountain samples were larger in winter than in spring and summer. Moreover, GMDs of 3- and 4-ring PAHs were larger than 5- and 6-ring PAHs in the three types of atmospheres. Such differences in GMDs may be interpreted by coagulation and repartitioning of organic compound during a long range transport from the inland continent to the marine site, suggesting that the size changes arising from these physical processes must be included in climate models in relevant to organic aerosols.

scholarly journals Size distributions of elemental carbon in the atmosphere of a coastal urban area in South China: characteristics, evolution processes, and implications for the mixing state

2008 ◽  
Vol 8 (19) ◽  
pp. 5843-5853 ◽  
Author(s):  
X.-F. Huang ◽  
J. Z. Yu
Keyword(s):  
Urban Area ◽  
Elemental Carbon ◽  
Southern China ◽  
Global Climate ◽  
Particle Growth ◽  
Size Distributions ◽  
Hygroscopic Growth ◽  
Mixing State ◽  
Cloud Processing ◽  
Fine Mode

Abstract. Elemental carbon (EC), as one of the primary light-absorbing components in the atmosphere, has a significant impact on both regional and global climate. The environmental impacts of EC are strongly dependent on its particle size. Little is known about the size distribution characteristics of EC particles in China's ambient environments. We report size distributions of EC particles in the urban area of Shenzhen in Southern China. In our samples, EC was consistently found in two modes, a fine mode and a coarse mode. The majority of EC mass (~80%) in this coastal metropolitan city resided in particles smaller than 3.2 μm in diameter. The fine mode peaked at around either 0.42 μm or 0.75 μm. While the mode at 0.42 μm could be ascribed to fresh vehicular emissions in the region, the mode at 0.75 μm was likely a result of particle growth from smaller EC particles. We theoretically investigated the particle growth processes that caused the EC particles to grow from 0.42 μm to 0.75 µm in the atmosphere. Our calculations indicate that the EC peak at 0.75 μm was not produced through either coagulation or H2SO4 condensation; both processes are too slow to lead to significant EC growth. Hygroscopic growth was also determined to be insignificant. Instead, addition of sulfate through in-cloud processing was found to cause significant growth of the EC particles and to explain the EC peak at 0.75 μm. We also estimated the mixing state of EC from the EC size distributions. In the droplet size, at least 45–60% of the EC mass in the summer samples and 68% of the EC mass in the winter samples was internally mixed with sulfate as a result of in-cloud processing. This information on EC should be considered in models of the optical properties of aerosols in this region. Our results also suggest that the in-cloud processing of primary EC particles could increase the light absorbing capacities through mixing EC with sulfate.

scholarly journals Size distributions of elemental carbon in a coastal urban atmosphere in South China: characteristics, evolution processes, and implications for the mixing state

2007 ◽  
Vol 7 (4) ◽  
pp. 10743-10766
Author(s):  
Xiao-Feng Huang ◽  
Jian Zhen Yu
Keyword(s):  
South China ◽  
Elemental Carbon ◽  
Global Climate ◽  
Particle Growth ◽  
Urban Atmosphere ◽  
Size Distributions ◽  
Hygroscopic Growth ◽  
Mixing State ◽  
Cloud Processing ◽  
Fine Mode

Abstract. Elemental carbon (EC), as one of the primary light-absorbing components in the atmosphere, has a significant impact on both regional and global climate. The environmental impacts of EC are strongly dependent on its particle size. Little is known about the size distribution characteristics of EC particles in the ambient environments of China. We here report size distributions of EC in the urban area of Shenzhen in South China. EC consistently exhibited two modes, a fine and a coarse mode. The majority of EC (~80%) in this coastal metropolitan city resided in particles smaller than 3.2 μm in diameter. The fine mode peaked at around either 0.42 μm or 0.75 μm. While the mode at 0.42 μm could be ascribed to fresh vehicular emissions in this region, the mode at 0.75 μm had to be a result of particle growth from smaller EC particles. We made a theoretical investigation of the particle growth processes that were responsible for EC particles to grow from 0.42 μm to 0.75 μm in the atmosphere. Our calculations indicate that the EC peak at 0.75 μm could not be produced through either coagulation or H2SO4 condensation; both were too slow to lead to significant EC growth. Hygroscopic growth was also calculated to be impossible. Instead, addition of sulfate through in-cloud processing was found to be able to significantly grow EC particles to explain the EC peak at 0.75 μm. We also estimated from the EC size distributions the mixing state of EC. In the droplet size, at least 45–60% of EC mass in the summer samples and 68% of EC mass in the winter samples was internally mixed with sulfate as a result of in-cloud processing. Such information on EC needs to be considered in modeling aerosol optical properties in this region. Our results also suggest that the in-cloud processing of primary EC particles could enhance light absorbing capacities through mixing EC and sulfate.

The size and horizon of origin of fragments produced by deep ripping texture contrast soils

Soil Research ◽  
1987 ◽  
Vol 25 (2) ◽  
pp. 211 ◽  
Author(s):  
PS Blackwell ◽  
TW Green ◽  
KA Olsson
Keyword(s):  
Water Potential ◽  
Fragment Size ◽  
Geometric Mean ◽  
Soil Horizon ◽  
Size Distributions ◽  
Fine Soil ◽  
Mean Diameter ◽  
Fine Mode ◽  
Texture Contrast ◽  
Coarse Soil

Two texture contrast soils were cultivated by deep ripping when they were drier than their lower plastic limits. The size distribution and soil horizon-of-origin of the resulting fragments were measured. One soil, a transitional red-brown earth, had either been previously uncultivated below the A horizon or had been deep ploughed and gypsum added two years previously. There was much fragmentation and mixing of soil from both of the horizons. Fine soil (<2 mm diam.) from the A horizon reached the lower depths of the trough made by the ripping and coarse soil from the B horizon (>50 mm) was brought to near the surface. The fragment size distributions were characteristically bimodal. Fragments of the fine mode (<2 mm) came mainly from the A horizon, fragments of the coarse mode (11-25 mm or larger) came mainly from the B horizon. In the laboratory, clods from the deep ripped soil were crushed at the same low water potential (air dry). The crushing energy per unit mass (specific crushing energy) was inversely proportional to the normalized geometric mean diameter of the fragments produced. Suggestions are made for modelling the effects of deep ripping.

Characteristics of Asian Mosquito Saliva Allergens for Specific Diagnoses and Effective Therapies

2020 ◽  
Vol 21 (2) ◽  
pp. 153-158 ◽  
Author(s):  
Soung-Hoo Jeon
Keyword(s):  
Allergic Reaction ◽  
East Asia ◽  
East Asian ◽  
Diagnosis And Treatment ◽  
Recombinant Allergens ◽  
Systemic Reactions ◽  
The Future ◽  
Mosquito Saliva ◽  
The Difference ◽  
Future Direction

An allergic reaction to mosquitoes can result in severe or abnormal local or systemic reactions such as anaphylaxis, angioedema, and general urticarial or wheezing. The aim of this review is to provide information on mosquito saliva allergens that can support the production of highly specific recombinant saliva allergens. In particular, candidate allergens of mosquitoes that are well suited to the ecology of mosquitoes that occur mainly in East Asia will be identified and introduced. By doing so, the diagnosis and treatment of patients with severe sensitivity to mosquito allergy will be improved by predicting the characteristics of East Asian mosquito allergy, presenting the future direction of production of recombinant allergens, and understanding the difference between East and West.

scholarly journals Efficacy and Safety of a 3-Antigen (Pre-S1/Pre-S2/S) Hepatitis B Vaccine: Results of a Phase 3 Randomized Clinical Trial in the Russian Federation

2020 ◽  
Author(s):  
Elena V Esaulenko ◽  
Aleksey A Yakovlev ◽  
Genady A Volkov ◽  
Anastasia A Sukhoruk ◽  
Kirill G Surkov ◽  
...  
Keyword(s):  
Hepatitis B ◽  
Geometric Mean ◽  
Serious Adverse Events ◽  
Double Blind ◽  
Antigen Vaccine ◽  
Single Antigen ◽  
Antibody Titers ◽  
The Russian Federation ◽  
The Difference ◽  
Mean Concentration

Abstract Background This study compares the immunogenicity and safety of a 3-antigen (S/pre-S1/pre-S2) hepatitis B (HepB) vaccine (3AV), to a single antigen vaccine (1AV) in adults to support the registration of 3AV in Russia. Methods We conducted a randomized, double-blind, comparative study of 3-dose regimens of 3AV (10 μg) and 1AV (20 µg) in adults aged 18–45 years. We evaluated immunogenicity based on hepatitis B surface (HBs) antibody titers at days 1, 28, 90, 180, and 210, adverse and serious adverse events (SAEs) to study day 210. The primary outcome was based on the difference in rates of seroconversion at day 210 (lower bound 95% confidence interval [CI]: &gt; − 4%). Secondary outcomes were seroprotection rates (SPR), defined as anti-HBs ≥10 mIU/mL and anti-HBs geometric mean concentration (GMC). Results Rate of seroconversion in 3AV (100%) was noninferior to 1AV (97.9%) at study day 210 (difference: 2.1%, 95% CI: −2.0, 6.3%]) but significantly higher at study day 28. SPR at study day 210 was &gt;97% in both arms. Anti-HBs titers were significantly higher at study days 90 (P = .001) and 180 (P = .0001) with 3AV. Sex, age, and body mass index (BMI) had no impact on anti-HBs titers. The rates of local reactions related to vaccination were similar between vaccine arms (3AV vs 1AV) after the first (30% vs 18.8%, P = .15), second (20.0% vs 14.6%, P = .33), and third vaccination (14.9% vs 23.4%, P = .22). No SAEs were reported. Conclusions 3AV was noninferior to 1AV. 3AV induced high SPR, and there were no safety concerns. Clinical Trials Registration. NCT04209400.

scholarly journals IAP-AACM v1.0： Global to regional evaluation of the atmospheric chemistry model in CAS-ESM

2018 ◽  
Author(s):  
Ying Wei ◽  
Xueshun Chen ◽  
Huansheng Chen ◽  
Jie Li ◽  
Zifa Wang ◽  
...  
Keyword(s):  
East Asia ◽  
Spatial Variation ◽  
Atmospheric Chemistry ◽  
Comprehensive Evaluation ◽  
Correlation Coefficients ◽  
Full Description ◽  
Atmospheric Physics ◽  
Temporal And Spatial Variability ◽  
Fine Mode ◽  
Aerosol Effects

Abstract. In this study, a full description and comprehensive evaluation of a global-regional nested model, the Aerosol and Atmospheric Chemistry Model of the Institute of Atmospheric Physics (IAP-AACM), is presented for the first time. Not only the global budgets and distribution, but also a comparison of nested simulation over China against multi-datasets are investigated, benefiting from the access of air quality monitoring data in China since 2013 and the Model Inter-Comparison Study for Asia project. The model results and analysis can greatly help reduce uncertainties and understand model diversity in assessing global and regional aerosol effects, especially over East Asia and areas affected by East Asia. The 1-year simulation for 2014 shows that the IAP-AACM is within the range of other models, and well reproduces both spatial distribution and seasonal variation of trace gases and aerosols over major continents and oceans (mostly within the factor of two). The model nicely captures spatial variation for carbon monoxide except an underestimation over the ocean that also shown in other models, which suggests the need for more accurate emission rate of ocean source. For aerosols, the simulation of fine-mode particulate matter (PM2.5) matches observation well and it has a better simulating ability on primary aerosols than secondary aerosols. This calls for more investigation on aerosol chemistry. Furthermore, IAP-AACM shows the superiority of global model, compared with regional model, on performing regional transportation for the nested simulation over East Asia. For the city evaluation over China, the model reproduces variation of sulfur dioxide (SO2), nitrogen dioxide (NO2) and PM2.5 accurately in most cities, with correlation coefficients above 0.5. Compared to the global simulation, the nested simulation exhibits an improved ability to capture the high temporal and spatial variability over China. In particular, the correlation coefficients for PM2.5, SO2 and NO2 are raised by ~ 0.25, ~ 0.15 and ~ 0.2 respectively in the nested grid. The summary provides constructive information for the application of chemical transport models. In future, we recommend the model's ability to capture high spatial variation of PM2.5 is yet to be improved.

Measuring Surface Uniformity in Chemical Mechanical Polishing

2009 ◽  
Vol 76-78 ◽  
pp. 459-464
Author(s):  
Jae Won Baik ◽  
Chang Wook Kang
Keyword(s):  
Chemical Mechanical Polishing ◽  
Geometric Mean ◽  
Mechanical Polishing ◽  
Wafer Surface ◽  
Semiconductor Wafer ◽  
Statistical Process ◽  
Significant Step ◽  
The Difference ◽  
Thickness Variations ◽  
The Stability

Chemical mechanical polishing (CMP) is a technique used in semiconductor fabrication for planarizing the top surface of an in-process semiconductor wafer. Especially, Post-CMP thickness variations are known to have a severe impact on the stability of downstream processes and ultimately on device yield. Hence understanding how to quantify and characterize this non-uniformity is significant step towards statistical process control to achieve higher quality and enhanced productivity. The main reason is that the non-uniformed interface between the wafer and the machine-pad adversely affects the polishing performance and ultimate surface uniformity. The purpose of this paper is to suggest a new measure that estimates the uniformity of wafer surface considering the difference of the amount of abrasion between the center and the edge. This new measure which is called the Coefficient of Uniformity is defined as the following ratio: Geometric Mean (GM) / Arithmetic Mean (AM). This metric can be evaluated regionally to quantify the non-uniformity on the wafer surface from the center to the edge. Further simulations show that this new measure is insensitive to shift of the wafer center and sensitive to shift of the wafer edge. This trend indicates that this new measure is a very useful to test the non-uniformity of wafer after CMP polishing.

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