scholarly journals A model for the size distribution of marine microplastics: A statistical mechanics approach

PLoS ONE ◽  
2021 ◽  
Vol 16 (11) ◽  
pp. e0259781
Author(s):  
Kunihiro Aoki ◽  
Ryo Furue
Keyword(s):  
Statistical Mechanics ◽  
Size Distribution ◽  
Gradual Increase ◽  
Rapid Decrease ◽  
The Other ◽  
Sea Surface ◽  
Size Distributions ◽  
Occurrence Probability ◽  
Biological Uptake ◽  
Data Source

The size distribution of marine microplastics provides a fundamental data source for understanding the dispersal, break down, and biotic impacts of the microplastics in the ocean. The observed size distribution at the sea surface generally shows, from large to small sizes, a gradual increase followed by a rapid decrease. This decrease has led to the hypothesis that the smallest fragments are selectively removed by sinking or biological uptake. Here we propose a new model of size distribution, focusing on the fragmentation of marine plastics. The model is inspired by ideas from statistical mechanics. In this model, the original large plastic piece is broken into smaller pieces once by the application of “energy” or work by waves or other processes, under two assumptions, one that fragmentation into smaller pieces requires larger energy and the other that the occurrence probability of the “energy” exponentially decreases toward larger energy values. Our formula well reproduces observed size distributions over wide size ranges from micro- to mesoplastics. According to this model, the smallest fragments are fewer because large “energy” required to produce such small fragments occurs more rarely.

Are smaller microplastics missing?

2020 ◽  
Author(s):  
Kunihiro Aoki ◽  
Ryo Furue
Keyword(s):  
Size Distribution ◽  
Gradual Increase ◽  
Black Body ◽  
Boltzmann Distribution ◽  
Black Body Radiation ◽  
Rapid Decrease ◽  
Size Distributions ◽  
Biological Uptake ◽  
Data Source ◽  
Planck’S Law

Abstract The size distribution of marine microplastics (< 5 mm) provides a fundamental data source for understanding the dispersal, break down, and biotic impacts of the microplastics in the ocean. The observed size distribution generally shows, from large to small sizes, a gradual increase followed by a rapid decrease. This decrease has led to the hypothesis that the smallest fragments are selectively removed by sinking or biological uptake. Here we propose a new model of size distribution without any removal of material from the system. The model uses an analogy with black-body radiation and the resultant size distribution is analogous to Planck's law. In this model, the original large plastic piece is broken into smaller pieces once by the application of “energy” or work by waves or other processes, under two assumptions, one that fragmentation into smaller pieces requires larger energy and the other that the probability distribution of the “energy” follows the Boltzmann distribution. Our formula well reproduces observed size distributions over wide size ranges from micro- (< 5 mm) to mesoplastics ( > 5 mm). According to this model, the smallest fragments are fewer because large “energy” required to produce such small fragments occurs more rarely.

scholarly journals Data imputation in in situ-measured particle size distributions by means of neural networks

2021 ◽  
Vol 14 (8) ◽  
pp. 5535-5554
Author(s):  
Pak Lun Fung ◽  
Martha Arbayani Zaidan ◽  
Ola Surakhi ◽  
Sasu Tarkoma ◽  
Tuukka Petäjä ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Meteorological Parameters ◽  
Number Concentration ◽  
The Other ◽  
Size Distributions ◽  
Ill Posed ◽  
Input Variables ◽  
Particle Sizer

Abstract. In air quality research, often only size-integrated particle mass concentrations as indicators of aerosol particles are considered. However, the mass concentrations do not provide sufficient information to convey the full story of fractionated size distribution, in which the particles of different diameters (Dp) are able to deposit differently on respiratory system and cause various harm. Aerosol size distribution measurements rely on a variety of techniques to classify the aerosol size and measure the size distribution. From the raw data the ambient size distribution is determined utilising a suite of inversion algorithms. However, the inversion problem is quite often ill-posed and challenging to solve. Due to the instrumental insufficiency and inversion limitations, imputation methods for fractionated particle size distribution are of great significance to fill the missing gaps or negative values. The study at hand involves a merged particle size distribution, from a scanning mobility particle sizer (NanoSMPS) and an optical particle sizer (OPS) covering the aerosol size distributions from 0.01 to 0.42 µm (electrical mobility equivalent size) and 0.3 to 10 µm (optical equivalent size) and meteorological parameters collected at an urban background region in Amman, Jordan, in the period of 1 August 2016–31 July 2017. We develop and evaluate feed-forward neural network (FFNN) approaches to estimate number concentrations at particular size bin with (1) meteorological parameters, (2) number concentration at other size bins and (3) both of the above as input variables. Two layers with 10–15 neurons are found to be the optimal option. Worse performance is observed at the lower edge (0.01<Dp<0.02 µm), the mid-range region (0.15<Dp<0.5 µm) and the upper edge (6<Dp<10 µm). For the edges at both ends, the number of neighbouring size bins is limited, and the detection efficiency by the corresponding instruments is lower compared to the other size bins. A distinct performance drop over the overlapping mid-range region is due to the deficiency of a merging algorithm. Another plausible reason for the poorer performance for finer particles is that they are more effectively removed from the atmosphere compared to the coarser particles so that the relationships between the input variables and the small particles are more dynamic. An observable overestimation is also found in the early morning for ultrafine particles followed by a distinct underestimation before midday. In the winter, due to a possible sensor drift and interference artefacts, the estimation performance is not as good as the other seasons. The FFNN approach by meteorological parameters using 5 min data (R2= 0.22–0.58) shows poorer results than data with longer time resolution (R2= 0.66–0.77). The FFNN approach using the number concentration at the other size bins can serve as an alternative way to replace negative numbers in the size distribution raw dataset thanks to its high accuracy and reliability (R2= 0.97–1). This negative-number filling approach can maintain a symmetric distribution of errors and complement the existing ill-posed built-in algorithm in particle sizer instruments.

A THEORY OF THE SIZE DISTRIBUTION OF PARTICLES IN A COMMINUTED SYSTEM

1943 ◽  
Vol 21a (6) ◽  
pp. 57-64 ◽  
Author(s):  
Laurence Griffith
Keyword(s):  
Statistical Mechanics ◽  
Size Distribution ◽  
Size Distributions ◽  
Colloidal Systems ◽  
Mathematical Procedure ◽  
Classical Statistical Mechanics ◽  
Distribution Laws ◽  
Size Distribution Of Particles

It is shown that the problem of the size distribution of particles in a system that has been ground can be treated by the general methods of the theory of probability. The mathematical procedure employed is almost identical m form with that used in the classical statistical mechanics of gases, although the fundamental ideas are different, as the molecules of a solid are not free to move. The distribution laws developed agree with the known empirical laws for particles of sizes down to about one micron, but proof of the theory will depend upon study of size distributions in colloidal systems.

Kecakapan Hidup Abad Ke-21 dalam Tokoh Utama Dongeng Jawa Timur Kajian Antropologi Sastra

2020 ◽  
Vol 13 (2) ◽  
pp. 168
Author(s):  
Rian Damariswara
Keyword(s):  
Critical Thinking ◽  
21St Century ◽  
Fairy Tales ◽  
Life Skills ◽  
Fairy Tale ◽  
Good Life ◽  
The Other ◽  
Main Character ◽  
Data Source ◽  
Creativity And Innovation

ABSTRAKTokoh utama dalam dongeng Jawa Timur memiliki sisi lain yang perlu diungkap. Sisi lain tersebut, yakni kecakapan hidup yang dimiliki tokoh utama dalam menyelesaikan masalah yang dihadapinya. Kecakapan hidup tersebut, memiliki relevansi dengan kecakapan hidup di abad ke-21. Jadi, dengan menganalisis kecakapan hidup tokoh utama secara otomatis peneliti dan pembaca dapat mengetahui bahwa tokoh-tokoh dongeng yang terdapat di Jawa Timur memiliki budaya hidup yang baik untuk dijadikan contoh dan motivasi.Untuk mengungkap kecakapan hidup abad ke-21 pada tokoh utama dongeng Jawa Timur menggunakan kajian antropologi sastra.Penelitian ini termasuk deskriptif kualitatif. Sumber data adalah teks dongeng Jawa Timur. Teknik yang digunakan adalah studi dokumenter. Kecakapan hidup abad ke-21 yang ditemukan pada dongeng Jawa Timur sebagai berikut. Pertama, berpikir kritis dan pemecahan masalah. Semua tokoh utama dalam dongeng memiliki pemikiran kritis sehingga dapat memecahkan masalah. Kedua, kreativitas dan inovasi yang ditemukan yakni jenis pengembangan dan sintesis. Inovasi pengembangan yang ditemukan adalah adanya alat bajak sawah dari batu menjadi kayu dan ditarik sapi serta dapat dipergunakan sebagai sarana hiburan. Alat tersebut diberi nama karapan sapi.  Inovasi sintesis adalah menggabungkan segala sesuatu yang dimiliki untuk dijadikan sesuatu yang baru. Seperti pada dongeng Asal Mula Reog Ponorogo,yakni menggabungkan kepala tokoh Singabarong dengan burung merak sehingga dinamakan reog ponorogo. Ketiga, kolaborasi antaranggota dan pemimpin dengan bawahan. Keempat, komunikasi yakni berupa diskusi, pengarahan, berkeluh kesah, dan perintah.Kata kunci: Kecakapan hidup abad ke-21, Tokoh utama, DongengABSTRACTThe main character in the East Java fable has another side that needs to be revealed. The other side, namely the life skills possessed by the main character in solving the problems they face. Life skills, have relevance to 21st century life skills. Therefore, by analyzing the life skills of the main characters automatically the researcher and reader can find out that the fairy tale figures in East Java which have a good life culture to be used as an example and motivation. To uncover 21st century life skills in the main characters of the East Javanese fable, the study of literary anthropology is used. This research is descriptive qualitative. The data source is the text of a fairy tale in East Java. The technique used is documentary study. The 21st century life skills found in the East Java fable are as follows. First, critical thinking and problem solving. All the main characters in fairy tales have critical thinking so they can solve problems. Second, the creativity and innovation found are types of development and synthesis. Development innovation that was found was the existence of a rice plow from stone to wood and pulled by cows and could be used as a means of entertainment. The tool is named Karapan Sapi. Synthesis of innovation is to combine everything that is owned to be something new. As in the fable of Reog Ponorogo, which combines the head of the Singabarong character with a peacock so it is called Reog Ponorogo. Third, collaboration between members and leaders with subordinates. Fourth, communication in the form of discussion, direction, complaints, and orders.Keyword: 21st century life skills, The main character, Fairy tale

scholarly journals Effect of Strain-Induced Precipitation on the Recrystallization Kinetics in a Model Alloy

2021 ◽  
Author(s):  
Mo Ji ◽  
Martin Strangwood ◽  
Claire Davis
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Avrami Exponent ◽  
Model Alloy ◽  
Size Distributions ◽  
Recrystallization Kinetics ◽  
Grain Size Distributions ◽  
Recrystallized Grain Size ◽  
Nb Addition

AbstractThe effects of Nb addition on the recrystallization kinetics and the recrystallized grain size distribution after cold deformation were investigated by using Fe-30Ni and Fe-30Ni-0.044 wt pct Nb steel with comparable starting grain size distributions. The samples were deformed to 0.3 strain at room temperature followed by annealing at 950 °C to 850 °C for various times; the microstructural evolution and the grain size distribution of non- and fully recrystallized samples were characterized, along with the strain-induced precipitates (SIPs) and their size and volume fraction evolution. It was found that Nb addition has little effect on recrystallized grain size distribution, whereas Nb precipitation kinetics (SIP size and number density) affects the recrystallization Avrami exponent depending on the annealing temperature. Faster precipitation coarsening rates at high temperature (950 °C to 900 °C) led to slower recrystallization kinetics but no change on Avrami exponent, despite precipitation occurring before recrystallization. Whereas a slower precipitation coarsening rate at 850 °C gave fine-sized strain-induced precipitates that were effective in reducing the recrystallization Avrami exponent after 50 pct of recrystallization. Both solute drag and precipitation pinning effects have been added onto the JMAK model to account the effect of Nb content on recrystallization Avrami exponent for samples with large grain size distributions.

scholarly journals Remote sensing of water cloud droplet size distributions using the backscatter glory: a case study

2004 ◽  
Vol 4 (5) ◽  
pp. 1255-1263 ◽  
Author(s):  
B. Mayer ◽  
M. Schröder ◽  
R. Preusker ◽  
L. Schüller
Keyword(s):  
Remote Sensing ◽  
Size Distribution ◽  
Droplet Size ◽  
Cloud Droplet ◽  
Droplet Size Distribution ◽  
Single Scattering ◽  
Effective Radius ◽  
Radiative Properties ◽  
High Angular Resolution ◽  
Size Distributions

Abstract. Cloud single scattering properties are mainly determined by the effective radius of the droplet size distribution. There are only few exceptions where the shape of the size distribution affects the optical properties, in particular the rainbow and the glory directions of the scattering phase function. Using observations by the Compact Airborne Spectrographic Imager (CASI) in 180° backscatter geometry, we found that high angular resolution aircraft observations of the glory provide unique new information which is not available from traditional remote sensing techniques: Using only one single wavelength, 753nm, we were able to determine not only optical thickness and effective radius, but also the width of the size distribution at cloud top. Applying this novel technique to the ACE-2 CLOUDYCOLUMN experiment, we found that the size distributions were much narrower than usually assumed in radiation calculations which is in agreement with in-situ observations during this campaign. While the shape of the size distribution has only little relevance for the radiative properties of clouds, it is extremely important for understanding their formation and evolution.

scholarly journals Consistency of causal claims in observational studies: a review of papers published in a general medical journal

BMJ Open ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. e043339
Author(s):  
Camila Olarte Parra ◽  
Lorenzo Bertizzolo ◽  
Sara Schroter ◽  
Agnès Dechartres ◽  
Els Goetghebeur
Keyword(s):  
Medical Journal ◽  
Observational Studies ◽  
The Other ◽  
Research Papers ◽  
General Medical Journal ◽  
Outcome Relationship ◽  
Causal Statement ◽  
Data Source ◽  
Published Research ◽  
Causal Language

ObjectiveTo evaluate the consistency of causal statements in observational studies published in The BMJ.DesignReview of observational studies published in a general medical journal.Data sourceCohort and other longitudinal studies describing an exposure-outcome relationship published in The BMJ in 2018. We also had access to the submitted papers and reviewer reports.Main outcome measuresProportion of published research papers with ‘inconsistent’ use of causal language. Papers where language was consistently causal or non-causal were classified as ‘consistently causal’ or ‘consistently not causal’, respectively. For the ‘inconsistent’ papers, we then compared the published and submitted version.ResultsOf 151 published research papers, 60 described eligible studies. Of these 60, we classified the causal language used as ‘consistently causal’ (48%), ‘inconsistent’ (20%) and ‘consistently not causal’(32%). Eleven out of 12 (92%) of the ‘inconsistent’ papers were already inconsistent on submission. The inconsistencies found in both submitted and published versions were mainly due to mismatches between objectives and conclusions. One section might be carefully phrased in terms of association while the other presented causal language. When identifying only an association, some authors jumped to recommending acting on the findings as if motivated by the evidence presented.ConclusionFurther guidance is necessary for authors on what constitutes a causal statement and how to justify or discuss assumptions involved. Based on screening these papers, we provide a list of expressions beyond the obvious ‘cause’ word which may inspire a useful more comprehensive compendium on causal language.

Factors Influencing the Particle Size Distribution in an Abrasive Waterjet

1991 ◽  
Vol 113 (4) ◽  
pp. 402-411 ◽  
Author(s):  
T. J. Labus ◽  
K. F. Neusen ◽  
D. G. Alberts ◽  
T. J. Gores
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Cutting Speed ◽  
Target Material ◽  
Abrasive Waterjet ◽  
Sieve Analysis ◽  
Size Distributions ◽  
Mixing Process ◽  
Jet Mixing

A basic investigation of the factors which influence the abrasive jet mixing process was conducted. Particle size analysis was performed on abrasive samples for the “as-received” condition, at the exit of the mixing tube, and after cutting a target material. Grit size distributions were obtained through sieve analysis for both water and air collectors. Two different mixing chamber geometries were evaluated, as well as the effects of pressure, abrasive feed rate, cutting speed, and target material properties on particle size distributions. An analysis of the particle size distribution shows that the main particle breakdown is from 180 microns directly to 63 microns or less, for a nominal 80 grit garnet. This selective breakdown occurs during the cutting process, but not during the mixing process.

scholarly journals On the Shape–Slope Relation of Drop Size Distributions in Convective Rain

2005 ◽  
Vol 44 (7) ◽  
pp. 1146-1151 ◽  
Author(s):  
Axel Seifert
Keyword(s):  
Size Distribution ◽  
Gamma Distribution ◽  
Drop Size ◽  
Empirical Relation ◽  
Size Distributions ◽  
Shape Parameters ◽  
Raindrop Size Distribution ◽  
Raindrop Size ◽  
Drop Size Distributions ◽  
Good Agreement

Abstract The relation between the slope and shape parameters of the raindrop size distribution parameterized by a gamma distribution is examined. The comparison of results of a simple rain shaft model with an empirical relation based on disdrometer measurements at the surface shows very good agreement, but a more detailed discussion reveals some difficulties—for example, deviations from the gamma shape and the overestimation of collisional breakup.

scholarly journals Ethylene and Lipoxygenase In Relation to Afterripening of Dormant NC-13 Peanut Seeds1,2

1985 ◽  
Vol 12 (1) ◽  
pp. 45-49 ◽  
Author(s):  
D. L. Ketring ◽  
H. E. Pattee
Keyword(s):  
Heat Treatment ◽  
Cold Storage ◽  
Ethylene Production ◽  
Sharp Increase ◽  
Gradual Increase ◽  
The Other ◽  
Immature Seeds ◽  
Positive Correlations ◽  
Mature Seeds

Abstract Following harvest, peanuts are usually subjected to a period of storage. During storage biochemical changes are known to occur. The objectives of this study were to determine the changes and relationship in ethylene production, germination, and lipoxygenase (LG) activity during cold storage of dormant NC-13 peanut seeds. Two seed lots (SL) were used: one grown in Oklahoma (SL80) and the other grown in N. Carolina (SL81). SL80 and SL81 were stored at 2 to 5 C for 193 and 242 days, respectively. Samples were taken at about 28-day intervals for determination of germination, ethylene production, and LG activity. Seeds of two and three maturities were tested for SL80 and SL81, respectively. As afterripening of stored seeds proceeded, ethylene production gradually increased, with the maximum at 48 hours of germination. Germination showed a concomitant gradual increase. Lipoxygenase activity of both seedlots was less for mature than for immature seeds and showed a sharp increase during storage at 2 to 5 C, particularly for immature seeds. After heat-treatment to break dormancy of sublots from SL81, there was a progessive increase in ethylene production and germination, but most notably for mature seeds. In contrast to ethylene production and germination, after heat-treatment LG activity declined. Linear correlation coefficient (r) values between ethylene production and germination were highly significant for mature seeds from SL80 at 48 and 72 hours of germination, but only at 72 hours for immature seeds. For SL81 as for SL80, significant positive correlations were found between ethylene production and germination. However, correlations between LG activity and the other variables were not significant except for mature seeds from SL81. Significant positive correlations for both ethylene production and germination with LG activity also existed for these seeds. But after heat-treatment these correlations no longer occurred. The data indicate that the metabolic processes related to ethylene production and germination are occurring simultaneously with those of LG activity. The possibility that metabolites from LG activity serve as substrates for ethylene production can not be precluded.

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