نتایج جستجو برای: dust polarity

تعداد نتایج: 66900  

F. WEI Y. WU Z. JIA

Let G be a simple connected graph. The generalized polarity Wiener index of G is defined as the number of unordered pairs of vertices of G whose distance is k. Some formulas are obtained for computing the generalized polarity Wiener index of the Cartesian product and the tensor product of graphs in this article.

Introduction: In recent years, frequency and intensity of dust storms have been increased because of human destructive activities and caused significant loss in different aspects of hygienic and health, environmental and socio-economic sections. Therefore, detection and trace of dust storms in shortest time is the first effective step in preparation and implementation of strategic and operation...

Journal: :journal of occupational health and epidemiology 0
mr rezaei assistant professor of environmental sciences, natural resource and environment school, university of birjand, birjand, iran mh sayadi assistant professor of environmental sciences, natural resource and environment school, university of birjand, birjand, iran

background: composition of dust in the air due to contact with human via inhalation, ingestion and skin absorption will have a large impact on public health. in the learning environments such as universities, many people spend most of their day in contact with the dust. the purpose of this study was to evaluate the concentration of heavy metals lead, chromium and copper in the training space of...

ژورنال: کواترنری ایران 2018
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1-Interoduction: Air pollution has been considered as one of the global challenges. According to world health organization (WHO), dust particles are the 5th most dangerous cause of death 4.2 million in the world. According to the world meteorological organization (WMO), when the wind speed increases more than 15 m/s and the visibility decreases because of dust particles less than 1 km, it is c...

Mathematical chemistry is a branch of theoretical chemistry for discussion and prediction of the molecular structure using mathematical methods without necessarily referring to quantum mechanics. In theoretical chemistry, distance-based molecular structure descriptors are used for modeling physical, pharmacologic, biological and other properties of chemical compounds. The Wiener Polarity index ...

Azita Moheb Saeid Abedini Khorramie Shahram Moradi Dehagi

Three types of solvents with different polarity (cyclohexane, toluene and benzene), a nonionic surfactant Span 40 were used to prepare strontium aluminate (SrAl2O4) spinel nanoparticles by a reverse micelle method. The structure of SrAl2O4 nanoparticles was characterized by X-ray diffraction (XRD). The morphology and size of the synthesized materials were studied using field emission scanning e...

محمدیان, محمود ,

ABSTRACT Cotton dust is one of the chemical agents that cause air pollution in textile workshops. An investigation was done to measure cotton dust concentration in Mazandaran Province. 37 samples were collected by personal samplers devices and whatman filter papers of worker's inhalation zone of ambient air that contained total dust. 40 samples were collected by whatman filter papers and ho...

Journal: :جغرافیا و مخاطرات محیطی 0
حسین ملکوتی سمیرا باباحسینی

introduction atmospheric processes and their interactions with ground surface responsible for formation and evolution of a heavy dust storm are important for identifying dust transport pathways. spatial and temporal distribution of middle eastern dust for a severe dust event during 4-8 july 2009 was analyzed by weather research and forecasting with chemistry (wrf/chem) model simulations, in-sit...

Journal: :Journal of the American Chemical Society 2014
Siowling Soh Helena Liu Rebecca Cademartiri Hyo Jae Yoon George M Whitesides

Many processes involve the movement of a disordered collection of small particles (e.g., powders, grain, dust, and granular foods). These particles move chaotically, interact randomly among themselves, and gain electrical charge by contact electrification. Understanding the mechanisms of contact electrification of multiple interacting particles has been challenging, in part due to the complex m...

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