The First Observation of HOx radicals in the Chengyu Urban Agglomeration

2020 ◽  
Author(s):  
Xinping Yang ◽  
Keding Lu ◽  
Xuefei Ma ◽  
Yuanhang Zhang
Keyword(s):  
New York ◽  
Urban Agglomeration ◽  
Oxidation Products ◽  
Oh Radicals ◽  
Secondary Pollution ◽  
Sensitivity Tests ◽  
Reaction Channels ◽  
Daily Concentration ◽  
Field Campaigns

<p>A comprehensive field campaign was carried out in summer 2019 in Chengdu, which obtained the first complete radical dataset of Chengyu Urban Agglomeration. Observed daily concentration maxima of radicals by the laser-induced-fluorescence (LIF) technique were in the range of (2-10)×10<sup>6</sup> cm<sup>-3</sup> for OH and (4-15)×10<sup>8</sup> cm<sup>-3</sup> for HO<sub>2</sub>. During daytime, OH reactivities were generally high (5-32 s<sup>-1</sup>). The missing reactivity was not be observed within uncertainty, and inorganics, observed VOCs and the calculated oxidation products contributed about one-third in total reactivity, respectively.</p><p>The chemical box model RACM 2 was used to interpret the observed radical concentrations. The model over-predicted OH and HO<sub>2</sub> at noon during the O<sub>3</sub> polluted episode. Constraining the model by the observed HO<sub>2</sub> concentration, the overestimation of OH can be explained almost by the overestimation of HO<sub>2</sub>. Besides, as in the previous field campaigns (e.g. Pennsylvania, Mexico City, New York and so on), the underestimation of the net conversion of OH into HO<sub>2</sub> enlarged with the increasing NO concentration, indicating the conversion of HO<sub>2</sub> into OH still need to be studied based on the discussion above. Different schemes to improve the agreement between observed and modelled HO<sub>2</sub> were explored in this work. The sensitivity tests indicated observed and modelled HO<sub>2</sub> can be agreed well by reducing the HO<sub>2</sub> yield in the reaction of OH and HCHO a half.</p><p>The oxidation rate of primary pollutants dominated by OH radicals was significantly higher than that in winter Beijing, which contributes significantly to secondary pollution, especially O<sub>3</sub>. Besides, the atmospheric self-cleaning ability and recycling efficiency both peaked for about 600 pptv of NO, indicating small amounts of NO can help to maintain the atmospheric oxidation. The campaign emphasizes the important role of HO<sub>2</sub> yield in the reaction channels of OH and VOCs especially, and the need for further laboratory experiments of the HO<sub>2</sub> yield measurement in order to understand radical chemistry in VOC-rich air.</p>

scholarly journals Missing OH source in a suburban environment near Beijing: observed and modelled OH and HO<sub>2</sub> concentrations in summer 2006

2013 ◽  
Vol 13 (2) ◽  
pp. 1057-1080 ◽  
Author(s):  
K. D. Lu ◽  
A. Hofzumahaus ◽  
F. Holland ◽  
B. Bohn ◽  
T. Brauers ◽  
...  
Keyword(s):  
Urban Areas ◽  
Pearl River Delta ◽  
Oxidation Products ◽  
Chemical Degradation ◽  
Beijing City ◽  
Air Chemistry ◽  
Daily Concentration ◽  
The Pearl River ◽  
Special Case

Abstract. Measurements of ambient OH and HO2 radicals were performed by laser induced fluorescence (LIF) during CAREBeijing2006 (Campaigns of Air Quality Research in Beijing and Surrounding Region 2006) at the suburban site Yufa in the south of Beijing in summer 2006. On most days, local air chemistry was influenced by aged air pollution that was advected by a slow, almost stagnant wind from southern regions. Observed daily concentration maxima were in the range of (4–17) × 106 cm−3 for OH and (2–24) × 108 cm−3 for HO2 (including an estimated interference of 25% from RO2). During daytime, OH reactivities were generally high (10–30 s−1) and mainly contributed by observed VOCs and their calculated oxidation products. The comparison of modelled and measured HOx concentrations reveals a systematic underprediction of OH as a function of NO. A large discrepancy of a factor 2.6 is found at the lowest NO concentration encountered (0.1 ppb), whereas the discrepancy becomes insignificant above 1 ppb NO. This study extends similar observations from the Pearl-River Delta (PRD) in South China to a more urban environment. The OH discrepancy at Yufa can be resolved, if NO-independent additional OH recycling is assumed in the model. The postulated Leuven Isoprene Mechanism (LIM) has the potential to explain the gap between modelled and measured OH at Beijing taking into account conservative error estimates, but lacks experimental confirmation. This and the hereby unresolved discrepancy at PRD suggest that other VOCs besides isoprene might be involved in the required, additional OH recycling. Fast primary production of ROx radicals up to 7 ppb h−1 was determined at Beijing which was dominated by the photolysis of O3, HONO, HCHO, and dicarbonyls. For a special case, 20 August, when the plume of Beijing city was encountered, a missing primary HOx source (about 3 ppb h−1) was determined under high NOx conditions similar to other urban areas like Mexico City. CAREBeijing2006 emphasizes the important role of OVOCs as a radical source and sink, and the need for further investigation of the chemical degradation of VOCs in order to better understand radical chemistry in VOC-rich air.

38. Max Brodel (1870-1941): His artistic influence on surgical learning at John Hopkins Medical School

2007 ◽  
Vol 30 (4) ◽  
pp. 47
Author(s):  
P. Pace-Asciak ◽  
T. Gelfand
Keyword(s):  
New York ◽  
Neck Surgery ◽  
The United States ◽  
Spoken Word ◽  
Medical Illustration ◽  
3 Dimensional ◽  
Teaching Anatomy ◽  
Computer Based ◽  
Pathological Disease

Medical students depend on illustration to learn anatomical facts and details that may be too subtle for the written or spoken word. For surgical disciplines, learners rely on tools such as language, 2-dimensional illustrations, and 3-dimensional models to pass on important concepts. Although a photograph can convey factual information, illustration can highlight and educate the pertinent details for understanding surgical procedures, neurovascular structures, and the pathological disease processes. In order to understand the current role of medical illustration in education, one needs to look to the past to see how art has helped solve communication dilemmas when learning medicine. This paper focuses on Max Brodel (1870-1941), a German-trained artist who eventually immigrated to the United States to pursue his career as a medical illustrator. Shortly after his arrival in Baltimore, Brodel made significant contributions to medical illustration in Gynecology at John Hopkins University, and eventually in other fields of medicine such as Urology and Otolaryngology. Brodel is recognized as one of America’s most distinguished medical illustrators for creating innovative artistic techniques and founding the profession of medical illustration. Today, animated computer based art is synergistically used with medical illustration to educate students about anatomy. Some of the changes that have occurred with the advancement of computer technology will be highlighted and compared to a century ago, when illustrations were used for teaching anatomy due to the scarcity of cadavers. Schultheiss D, Udo J. Max Brodel (1870-1941) and Howard A.Kelly (1858-1943) – Urogynecology and the birth of modern medical illustration. European Journal of Obstetrics & gynecology and Reproductive Biology 1999; 86:113-115. Crosby C. Max Brodel: the man who put art into medicine. New York: Springer-Verlag, 1991. Papel ID. Max Brodel’s contributions to otolaryngology – Head and Neck surgery. The American Journal of Otology 1986; 7(6):460-469.

Neoliberalism, Law and its Discontents: Three Recent Interventions

2020 ◽  
Vol 23 (2) ◽  
Author(s):  
Ravi Malhotra
Keyword(s):  
New York ◽  
Princeton University ◽  
The Law

Honor Brabazon, ed. Neoliberal Legality: Understanding the Role of law in the neoliberal project (New York: Routledge, 2017). 214pp. Paperback.$49.95 Katharina Pistor. The Code of Capital: How the Law Creates Wealth and Inequality (Princeton: Princeton University Press, 2019). 297 pp. Hardcover.$29.95 Astra Taylor. Democracy May Not Exist, but We'll Miss It When It's Gone (New York: Metropolitan Books--Macmillan, 2019). Hardcover$27.00

Wilfred Ethier. Modern International Economics. New York: W. W. Norton and Company. 1983. xviii + 588 pp.

1988 ◽  
Vol 27 (1) ◽  
pp. 81-83
Author(s):  
Nadeem A. Burney
Keyword(s):  
International Economic ◽  
New York ◽  
Economic Theory ◽  
International Economics ◽  
International Monetary System ◽  
International Markets ◽  
The Past ◽  
Monetary System ◽  
Recent Developments

Its been long recognized that various economies of the world are interlinked through international trade. The experience of the past several years, however, has demonstrated that this economic interdependence is far greater than was previously realized. In this context, the importance of international economic theory as an area distinct from general economics hardly needs any mentioning. What gives international economic theory this distinction is international markets for some goods and effects of national sovereignty on the character of economic activity. Wilfred Ethier's book, which incorporates recent developments in the field, is an excellent addition to textbooks on international economics for one- or twosemester undergraduate courses. The book mostly covers standard topics. A distinguishing feature of this book is its detailed analysis of the flexible exchange rates and a discussion of the various approaches used for their determination. Within each chapter, the author has extensively used facts, figures and major events to clarify the concepts in the light of the theoretical framework. The book also discusses, in a fair amount of detail, the existing international monetary system and the role of various international organizations.

Conclusion

2017 ◽  
Author(s):  
Andrea Harris
Keyword(s):  
New York ◽  
Twentieth Century ◽  
New York City ◽  
Driving Force ◽  
George Balanchine ◽  
Current State ◽  
The Arts ◽  
History Of ◽  
Lincoln Center

The Conclusion briefly examines the current state of the New York City Ballet under the auspices of industrial billionaire David H. Koch at Lincoln Center. In so doing, it to introduces a series of questions, warranting still more exploration, about the rapid and profound evolution of the structure, funding, and role of the arts in America through the course of the twentieth century. It revisits the historiographical problem that drives Making Ballet American: the narrative that George Balanchine was the sole creative genius who finally created an “American” ballet. In contrast to that hagiography, the Conclusion reiterates the book’s major contribution: illuminating the historical construction of our received idea of American neoclassical ballet within a specific set of social, political, and cultural circumstances. The Conclusion stresses that the history of American neoclassicism must be seen as a complex narrative involving several authors and discourses and crossing national and disciplinary borders: a history in which Balanchine was not the driving force, but rather the outcome.

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