نتایج جستجو برای: nitrogen cycle

تعداد نتایج: 386826  

F. Mahboubi, K. Taherkhani,

Nitriding is a surface treatment technique used to introduce nitrogen into metallic materials to improve their surface hardness, mechanical properties, wear resistance and corrosion resistance. In this research, the effects of plasma nitriding parameters including frequency and duty cycle were investigated on samples with different grooves dimensions. Steel blocks prepared from DIN1.2344 hot wo...

Journal: :Science 2010
Donald E Canfield Alexander N Glazer Paul G Falkowski

Atmospheric reactions and slow geological processes controlled Earth's earliest nitrogen cycle, and by ~2.7 billion years ago, a linked suite of microbial processes evolved to form the modern nitrogen cycle with robust natural feedbacks and controls. Over the past century, however, the development of new agricultural practices to satisfy a growing global demand for food has drastically disrupte...

2013
H. Calderon C. Gularte S. Hand M. McBee M. Taborn J. Tran Dr. Kung - Hui Chu

Human activities related to nitrogen have caused an overarching problem ‐ an imbalance in the global nitrogen cycle. Through conventional wastewater treatment processes, mainly a combination of aerobic nitrification and anoxic denitrification processes, ammonia and other forms of nitrogen can be converted into nitrogen gas and return back to the nitrogen cycle. However, this approach not only r...

2009
Atul Jain Xiaojuan Yang Haroon Kheshgi A. David McGuire Wilfred Post David Kicklighter

[1] Nitrogen cycle dynamics have the capacity to attenuate the magnitude of global terrestrial carbon sinks and sources driven by CO2 fertilization and changes in climate. In this study, two versions of the terrestrial carbon and nitrogen cycle components of the Integrated Science Assessment Model (ISAM) are used to evaluate how variation in nitrogen availability influences terrestrial carbon s...

Journal: :Reviews in Environmental Science and Bio/Technology 2002

2015
R. M. Rees U. M. Skiba B. D. Stocker M. Rinaldi M. C. Facchini C. R. Flechard J. N. Galloway

Introduction Conclusions References

2014
Benjamin Charnay François Forget Gabriel Tobie Christophe Sotin Robin Wordsworth

Several clues indicate that Titan’s atmosphere has been depleted in methane during some period of its history, possibly as recently as 0.5-1 billion years ago. It could also happen in the future. Under these conditions, the atmosphere becomes only composed of nitrogen with a range of temperature and pressure allowing liquid or solid nitrogen to condense. Here, we explore these exotic climates t...

2017
Stephen M. Techtman Nagissa Mahmoudi Kendall T. Whitt Maria Fernanda Campa Julian L. Fortney Dominique C. Joyner Terry C. Hazen

The nitrogen cycle in the marine environment is strongly affected by ammonia-oxidizing Thaumarchaeota. In some marine settings, Thaumarchaeotes can comprise a large percentage of the prokaryotic population. To better understand the biogeographic patterns of Thaumarchaeotes, we sought to investigate differences in their abundance and phylogenetic diversity between geographically distinct basins....

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