scholarly journals Tracking How Plastic Moves in the Coastal Ocean

Eos ◽  
2020 ◽  
Vol 101 ◽  
Author(s):  
Kate Wheeling
Keyword(s):  
Particle Density ◽  
Coastal Ocean ◽  
Wave Tank ◽  
Drift Behavior

Researchers used a wave tank to study the movement of plastic particles experimentally and to understand the role of particle density in drift behavior.

scholarly journals DOM degradation by light and microbes along the Yukon River-coastal ocean continuum

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Brice K. Grunert ◽  
Maria Tzortziou ◽  
Patrick Neale ◽  
Alana Menendez ◽  
Peter Hernes
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Salinity Gradient ◽  
Coastal Ocean ◽  
Interactive Effects ◽  
The Arctic ◽  
Yukon River ◽  
Spring Freshet ◽  
Dom Composition

AbstractThe Arctic is experiencing rapid warming, resulting in fundamental shifts in hydrologic connectivity and carbon cycling. Dissolved organic matter (DOM) is a significant component of the Arctic and global carbon cycle, and significant perturbations to DOM cycling are expected with Arctic warming. The impact of photochemical and microbial degradation, and their interactive effects, on DOM composition and remineralization have been documented in Arctic soils and rivers. However, the role of microbes, sunlight and their interactions on Arctic DOM alteration and remineralization in the coastal ocean has not been considered, particularly during the spring freshet when DOM loads are high, photoexposure can be quite limited and residence time within river networks is low. Here, we collected DOM samples along a salinity gradient in the Yukon River delta, plume and coastal ocean during peak river discharge immediately after spring freshet and explored the role of UV exposure, microbial transformations and interactive effects on DOM quantity and composition. Our results show: (1) photochemical alteration of DOM significantly shifts processing pathways of terrestrial DOM, including increasing relative humification of DOM by microbes by > 10%; (2) microbes produce humic-like material that is not optically distinguishable from terrestrial humics; and (3) size-fractionation of the microbial community indicates a size-dependent role for DOM remineralization and humification of DOM observed through modeled PARAFAC components of fluorescent DOM, either through direct or community effects. Field observations indicate apparent conservative mixing along the salinity gradient; however, changing photochemical and microbial alteration of DOM with increasing salinity indicate changing DOM composition likely due to microbial activity. Finally, our findings show potential for rapid transformation of DOM in the coastal ocean from photochemical and microbial alteration, with microbes responsible for the majority of dissolved organic matter remineralization.

The role of single-particle density in chemistry

1981 ◽  
Vol 53 (1) ◽  
pp. 95-126 ◽  
Author(s):  
Anjuli S. Bamzai ◽  
B. M. Deb
Keyword(s):  
Single Particle ◽  
Particle Density ◽  
Single Particle Density

Characteristics of three biochar types with different pyrolysis time as ameliorant of peat soil

2017 ◽  
Vol 51 (05) ◽  
Author(s):  
Urai Suci Yulies Vitri Indrawati ◽  
Azwar Ma’as ◽  
Nuryani Hidayah Utami ◽  
Eko Hanuddin
Keyword(s):  
Rice Husk ◽  
Particle Density ◽  
Lower Layer ◽  
Lignin Content ◽  
Peat Soil ◽  
Pyrolysis Product ◽  
Empty Fruit Bunches ◽  
Infrared Spectrometer ◽  
Rice Husk Biochar

Biochar is a pyrolysis product resulted from biomass burning in oxygen limited conditions and is expected to serve as soil ameliorant.In this paper a laboratory study was conducted using three types of biochar ( palm empty fruit bunches (tankos), rice husk and peat from Bengkalis). The study was aimed at identifying the characteristics of each biochar burned at a temperature of 350oC with different pyrolysis time (3, 4 and5 hours). The analysis of lignin content showed that the peat from Bengkalis has higher lignin (50.23%) followed by tankos (41.96%) and rice husk (18.40%). The results of Fourier Transform Infrared Spectrometer (FTIR) show lower-layer Bengkalis peat (A2) has more functional group than husk burned for three hours and four hours (12 types, 10 types and 10 types). The appearance of rice husk biochar surface pores pyrolyzed for 3 hours, with 1000x magnification is sturdy and orderly arranged, smaller macro and micro pore size (1.612 ìm; 1.800 ìm; 2.593 ìm) than that of husk biochar pyrolyzed for four hours (6.956 ìm; 9.402 ìm ; 5.012 µm). In Bengkalis peat (A2), the macro and micro pores are sturdy and orderly arranged, the size of the pores is partially collapsed so that it is smaller and cannot be measured. Large and orderly arranged structure and form of pores will increase the role of biochar as ameliorant in the soil. The formation of intact pore makes biochar better in terms of bulk density, particle density, and aeration.

scholarly journals Quantification of biomaterial dispersion during otologic procedures and role of barrier drapes in Covid 2019 era – a laboratory model

2020 ◽  
pp. 1-6
Author(s):  
P K Lokesh ◽  
S Chowdhary ◽  
S A Pol ◽  
M Rajeswari ◽  
S K Saxena ◽  
...  
Keyword(s):  
Temporal Bone ◽  
Particle Density ◽  
Particulate Material ◽  
Operating Theatre ◽  
Laboratory Model ◽  
Particle Count ◽  
Bone Surgery ◽  
Aerosol Generation ◽  
Temporal Bone Surgery

Abstract Background Aerosol generation during temporal bone surgery caries the risk of viral transmission. Steps to mitigate this problem are of particular importance during the coronavirus disease 2019 pandemic. Objective To quantify the effect of barrier draping on particulate material dispersion during temporal bone surgery. Methods The study involved a cadaveric model in a simulated operating theatre environment. Particle density and particle count for particles sized 1–10 μ were measured in a simulated operating theatre environment while drilling on a cadaveric temporal bone. The effect of barrier draping to decrease dispersion was recorded and analysed. Results Barrier draping decreased counts of particles smaller than 5 μ by a factor of 80 in the operating theatre environment. Both particle density and particle count showed a statistically significant reduction with barrier draping (p = 0.027). Conclusion Simple barrier drapes were effective in decreasing particle density and particle count in the operating theatre model and can prevent infection in operating theatre personnel.

What Is the Role of Fresh Groundwater and Recirculated Seawater in Conveying Nutrients to the Coastal Ocean?

2011 ◽  
Vol 45 (12) ◽  
pp. 5195-5200 ◽  
Author(s):  
Yishai Weinstein ◽  
Yoseph Yechieli ◽  
Yehuda Shalem ◽  
William C. Burnett ◽  
Peter W. Swarzenski ◽  
...  
Keyword(s):  
Coastal Ocean ◽  
Fresh Groundwater

Modeling the Role of Microstructure on Shear Instability with Reference to the Formability of Automotive Aluminium Alloys

2006 ◽  
Vol 519-521 ◽  
pp. 183-190 ◽  
Author(s):  
David S. Wilkinson ◽  
Xin Jian Duan ◽  
Ji Dong Kang ◽  
Mukesh K. Jain ◽  
J. David Embury
Keyword(s):  
Aluminium Alloys ◽  
Particle Density ◽  
Shear Bands ◽  
Rolling Direction ◽  
Shear Instability ◽  
Fe Model ◽  
Intermetallic Particles ◽  
Automotive Sheet ◽  
Cast Alloys

This paper addresses the effect of microstructure on the formability of aluminium alloys of interest for automotive sheet applications. The bulk of this work has been on the alloy AA5754 – both conventional DC cast alloys and continuous cast alloys made by twin belt casting. It is known that alloys such as these contain Fe as a tramp impurity which results in Fe-based intermetallic particles distributed through microstructure as isolated particles and in stringers aligned along the rolling direction. It is thought that these particles are the cause, both of the reduced ductility that is observed as the Fe level rises, and the relatively poor formability of strip cast alloys, as compared with those made by DC cast. Conventional wisdom suggests that the reduction of ductility is due to the effect of particles as nucleating sites for damage. However, most studies show that these materials are resistant to damage until just before fracture. We now believe that effect is actually related to the development of shear bands in these materials. We present experimental data which supports this conclusion. We then show how the FE models we have developed demonstrate the role of shear instability on fracture and the role played by hard particles. We show how a unit cell approach can be used to incorporate the effect of particle density and morphology on shear localization in a way that includes statistical variability due to microstructural heterogeneity. This leads to a set of constitutive equations in which the parameters are distributed from one region to another. These are then fed into a macroscopic FE model at the level of the specimen or the component in order to determine the effect of microstructural variability on shear instability and ductility.

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