scholarly journals The Effect of Nanoclay on Dust Generation during Drilling of PA6 Nanocomposites

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Sophia Sachse ◽  
Francesco Silva ◽  
Huijun Zhu ◽  
Adeel Irfan ◽  
Agnieszka Leszczyńska ◽  
...  
Keyword(s):  
Particle Deposition ◽  
Particle Concentration ◽  
Total Concentration ◽  
Ultrafine Particle ◽  
Polyamide 6 ◽  
Emission Rates ◽  
The Past ◽  
Dust Generation ◽  
Lack Of Information ◽  
Total Particle

During the past decade, polymer nanocomposites have emerged as a novel and rapidly developing class of materials and attracted considerable investment in research and development worldwide. However, there is currently a lack of information available in the literature on the nano and ultrafine particle emission rates from these materials. In this paper, influence of nanoclay on mechanical drilling of PA6 composites, in terms of dust generation, has been reported. With the help of real-time characterization, submicrometer-sized particles (5.6–512 nm), size distribution, and number concentration emitted from polyamide 6/nanoclay composites during mechanical drilling are studied. Total particle concentration for the PA6/nanoclay composites was 20,000 cm−3, while unreinforced panel measured a total concentration of approximately 400,000 cm−3. While the airborne particle concentration for the PA6/nanoclay composites was 20 times lower than for the PA6 matrix, the concentration of deposited nanoparticles doubled for the nanocomposite. The results clearly show that more particles in the size range between 175 and 350 nm are generated, during drilling of the nanocomposites, and these particles deposit in a shorter time. It is likely that the presence of nanoclay in some way retains the formation of high quantity of airborne particles and promotes particle deposition.

scholarly journals On the sub-micron aerosol size distribution in a coastal-rural site at El Arenosillo Station (SW-Spain)

2011 ◽  
Vol 11 (2) ◽  
pp. 3813-3856 ◽  
Author(s):  
M. Sorribas ◽  
B. A. de la Morena ◽  
B. Wehner ◽  
J. F. López ◽  
N. Prats ◽  
...  
Keyword(s):  
Size Distribution ◽  
Particle Concentration ◽  
Total Concentration ◽  
Total Surface Area ◽  
Rural Site ◽  
Aerosol Size Distribution ◽  
Land Breeze ◽  
Scanning Mobility Particle Sizer ◽  
Accumulation Mode ◽  
Total Particle

Abstract. This study is focused on the analysis of the sub-micron aerosol characteristics at rural and coastal environment in Southwestern Spain. Particle number size distributions were measured in the size range (14–673) nm using a Scanning Mobility Particle Sizer (SMPS, Model 3936-TSI), from 15 July 2004 to 31 July 2006 at El Arenosillo Station. Mean total concentration was 8660 cm−3 and mean concentrations for the nucleation, Aitken and accumulation modes particles were 2830 cm−3, 4110 cm−3 and 1720 cm−3, respectively. Mean geometric diameters of the four modes particles, which characterized the mean size distribution per month, were about 16 nm, 42 nm, 103 nm and 237 nm. Two kinds of episodes produced a maximum of the total concentration around noon: the new particle formation and the regional recirculation such as the sea-land breeze. Two types of nucleation events (called N$1 and N2) were observed. Events N1 were an example of the influence of regional sources and Events N2 showed the weight of local industries over the rural and coastal background levels. The 60% of nucleation events were related to NE and NW wind sectors (N1 and N2 respectively), a ΔT higher than 12 °C, a wind speed higher than 2.3 m s−1 and a total surface area for the accumulation mode particles below of 11 190 μ m2 cm−3. The influence of the sea-land breeze processes has been analyzed, observing increases of up to 50%, 110% and 90% of the particle concentration for the nucleation, Aitken and accumulation modes. Annual evolution of monthly averages allowed to conclude that the increase or decrease of 1 cm−3 of the concentration for nucleation mode particles was related to opposite trend of 0.5 cm−3 of the concentration for accumulation mode. This anti-correlation produced a weak seasonal evolution of the total particle concentration.

scholarly journals DNA Methylation Profiles of Tph1A and BDNF in Gut and Brain of L. Rhamnosus-Treated Zebrafish

Biomolecules ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 142
Author(s):  
Mariella Cuomo ◽  
Luca Borrelli ◽  
Rosa Della Monica ◽  
Lorena Coretti ◽  
Giulia De Riso ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Molecular Mechanisms ◽  
The Past ◽  
Targeted Analysis ◽  
Lack Of Information ◽  
High Resolution Power ◽  
Resolution Level ◽  
Health And Disease ◽  
High Doses ◽  
The Brain

The bidirectional microbiota–gut–brain axis has raised increasing interest over the past years in the context of health and disease, but there is a lack of information on molecular mechanisms underlying this connection. We hypothesized that change in microbiota composition may affect brain epigenetics leading to long-lasting effects on specific brain gene regulation. To test this hypothesis, we used Zebrafish (Danio Rerio) as a model system. As previously shown, treatment with high doses of probiotics can modulate behavior in Zebrafish, causing significant changes in the expression of some brain-relevant genes, such as BDNF and Tph1A. Using an ultra-deep targeted analysis, we investigated the methylation state of the BDNF and Tph1A promoter region in the brain and gut of probiotic-treated and untreated Zebrafishes. Thanks to the high resolution power of our analysis, we evaluated cell-to-cell methylation differences. At this resolution level, we found slight DNA methylation changes in probiotic-treated samples, likely related to a subgroup of brain and gut cells, and that specific DNA methylation signatures significantly correlated with specific behavioral scores.

A theory of aerosol deposition in the human respiratory tract

1975 ◽  
Vol 38 (1) ◽  
pp. 77-85 ◽  
Author(s):  
D. B. Taulbee ◽  
C. P. Yu
Keyword(s):  
Particle Size ◽  
Respiratory Tract ◽  
Particle Deposition ◽  
Particle Concentration ◽  
Diffusion Mechanism ◽  
Aerosol Deposition ◽  
Lung Model ◽  
Brownian Diffusion ◽  
Human Respiratory Tract ◽  
Apparent Diffusion

The deposition of inhaled aerosol particles in the human respiratory tract is due to the mechanisms of inertia impaction, Brownian diffusion, and gravitational settling. A theory is developed to predict the particle deposition and its distribution in human respiratory tract for any breathing condition. A convection-diffusion equation for the particle concentration with a loss term is used to describe the transport and deposition of particles. In this equation, an apparent diffusion coefficient due to the velocity dispersion in the lung is present and found to be the dominant diffusion mechanism for the cases considered here. Expressions for deposition by various mechanisms are also derived. The governing equation is solved numerically with Weibel's lung model A. The particle concentration at the mouth is calculated during washin and washout and compared favorably with experimental recordings for 0.5-mum diameter di(2-ethylhexyl) sebacate particles. The total deposition in the lung for particle size ranging from 0.05 to 5 mum is also computed for a 500-cm-3 tidal volume and 15 breaths/min. The results in general agree with recent measurements of Heyder et al. However, a particle size of minimum deposition is found to exist theoretically near 0.3 mum.

scholarly journals Physical handsheet properties of pulp furnishes containing attritor-treated fibers

TAPPI Journal ◽  
2017 ◽  
Vol 16 (01) ◽  
pp. 9-15
Author(s):  
David Knox ◽  
Peter W. Hart ◽  
Humphrey Moynihan ◽  
Nichole Kilgore
Keyword(s):  
Small Particle ◽  
Pulp Fibers ◽  
Processing Methods ◽  
Particle Generation ◽  
Cellulosic Fibers ◽  
The Past ◽  
Dry Processing ◽  
Lack Of Information ◽  
Wet Processing ◽  
The Impact

Several articles have been published during the past 30 years on different methods to produce micro- to nanosize cellulose particles from pulp. Unfortunately, a general lack of information exists on the impact of differing manufacturing process methods upon the product properties obtained from these differing methods. Literature data show that wet processing of small-sized cellulosic fibers generates handsheets with approximately equal or higher density and modulus of elasticity than controls for a given amount of added microcellulose. The current work evaluated small particle generation from pulp fibers via dry processing methods and compared the physical properties of dry versus wet processed particles. Dry processing to obtain microcellulose gave considerably lower sheet density and modulus as compared with wet processed microcellulose. The lower modulus can be compensated for by refining base fibers more aggressively to obtain higher density and higher modulus sheets. Dry processing methods for making microcellulose and their impact on final board properties, including modulus and smoothness, will be discussed.

SO2 Measurement with Sorption - Cumulative and Ultraviolet Fluorescent Method near Nováky Power Plant

2016 ◽  
Vol 832 ◽  
pp. 131-136
Author(s):  
Jozefína Pokrývková ◽  
Jakub Fuska ◽  
Viliam Bárek
Keyword(s):  
Power Plant ◽  
Total Concentration ◽  
Measuring Station ◽  
The Past ◽  
New Methods ◽  
Fluorescent Method ◽  
The Earth ◽  
Reduction Of Emissions ◽  
Harmful Substances ◽  
Pollution Impact

Satisfying of increasing demands of society has often resulted in uncontrolled discharges of harmful substances into the atmosphere. The situation is gradually improving over the past 50 years, but the environmental impact is still evident and it must be monitored and evaluated. Reduction of emissions released into the atmosphere and reduction of air pollution impact on the Earth surface occurs due to development of new methods and technologies in the industry and legislation. This paper deals with the possibilities of the two methods of the SO2 concentration measurements - sorption - cumulative and ultraviolet fluorescent method at the location of the power plant Novaky. In the imission area is built automated measuring station (AMS) Oslany (operated by ENVITECH, managed by Slovak Hydrometeorological Institute Bratislava) as the measure of the total concentration of the pollutant. The research have shown that the maximum concentration detected in this area reached up to 64.46 µg.m-3 of SO2

Infant Radiant Warmers

PEDIATRICS ◽  
1978 ◽  
Vol 61 (1) ◽  
pp. 113-114
Author(s):  
Keyword(s):  
Personal Communication ◽  
Neurological Damage ◽  
Additional Information ◽  
The Past ◽  
Lack Of Information ◽  
Improper Use ◽  
Disposable Diapers ◽  
Radiant Warmer ◽  
Sensor Probe ◽  
Delivery Rooms

Radiant warmers are frequently used in delivery rooms and neonatal care units when open access and external heat are simultaneously required.1 The sale of more than 13,000 units by U.S. manufacturers during the past ten years attests to the acceptance of these devices by pediatricians.2 However, some concern about the use of the warmers stems from potential hazards and the lack of information regarding possible effects of the devices. This concern was recently expressed by a panel of consultants to the Bureau of Medical Devices in the Food and Drug Administration (FDA) who recommended that the FDA obtain additional information to assist it in evaluating radiation warmer safety.3 If this recommendation is accepted by the FDA, current procedures require that additional information regarding the effects of radiant warmers on infants must be provided within a period of 30 months.4 Therefore, pediatricians should be aware of the issues involved. The most serious complication of radiant warmers is extreme hyperthermia, which may occur from improper use or from dislodgement of the sensor probe. Hyperthermia may result in death or permanent neurological damage (T. Peebles, personal communication). Insensible water loss increases markedly when infants are placed in the warm, dry, open environment under radiant warmers, and may increase by 50% to 200% over that observed among infants in incubators, depending on the maturity of the infant and the type of warmer.5 First-degree burns have been attributed to radiant warmer heating of plastic-lined disposable diapers which were placed next to the skin for urine collection.6

scholarly journals Effect of Flow Rate and Particle Concentration on the Transport and Deposition of Bare and Stabilized Zero-Valent Iron Nanoparticles in Sandy Soil

2019 ◽  
Vol 11 (23) ◽  
pp. 6608
Author(s):  
Ibrahim ◽  
Awad ◽  
Al-Farraj ◽  
Al-Turki
Keyword(s):  
Flow Rate ◽  
Sandy Soil ◽  
Particle Deposition ◽  
Particle Concentration ◽  
Soil Column ◽  
Relative Concentration ◽  
Methyl Cellulose ◽  
Maximum Flow ◽  
Breakthrough Curves ◽  
Zero Valent Iron

Efficient application of nanoscale zero-valent iron (nZVI) particles in remediation processes relies heavily on the ability to modify the surfaces of nZVI particles to enhance their stability and mobility in subsurface layers. We investigated the effect of sodium carboxy-methyl-cellulose (CMC) polymer stabilizer, pH, particle concentration, and flow rate on the transport of nZVI particles in sand columns. Breakthrough curves (BTCs) of nZVI particles indicated that the transport of nZVI particles was increased by the presence of CMC and by increasing the flow rate. The relative concentration (RC) of the eluted CMC–nZVI nanoparticles was larger at pH 9 as compared to RC at pH 7. This is mainly attributed to the increased nZVI particle stability at higher pH due to the increase in the electrostatic repulsion forces and the formation of larger energy barriers. nZVI particle deposition was larger at 0.1 cm min-1 flow due to the increased residence time, which increases the aggregation and settlement of particles. The amount of CMC–nZVI particles eluted from the sand columns was increased by 52% at the maximum flow rate of 1.0 cm min-1. Bare nZVI were mostly retained in the first millimeters of the soil column, and the amount eluted did not exceed 1.2% of the total amount added. Our results suggest that surface modification of nZVI particles was necessary to increase stability and enhance transport in sandy soil. Nevertheless, a proper flow rate, suitable for the intended remediation efforts, must be considered to minimize nZVI particle deposition and increase remediation efficiency.

Understanding Latinx Civic Engagement in a New Immigrant Gateway

2019 ◽  
Vol 41 (4) ◽  
pp. 447-463 ◽  
Author(s):  
J. Claire Schuch ◽  
Ligia M. Vasquez-Huot ◽  
Wendy Mateo-Pascual
Keyword(s):  
North Carolina ◽  
Civic Engagement ◽  
Household Income ◽  
Political Representation ◽  
Strongly Correlated ◽  
Charitable Organization ◽  
Faith Based ◽  
The Past ◽  
Lack Of Information ◽  
Documentation Status

The U.S. South has experienced rapid Latinx growth; yet, little is known about how Latinx residents are civically integrating into new communities. This article explores whether, where, and why Latinx in Charlotte-Mecklenburg, North Carolina, are civically engaged. Participants in a Latino Civic Engagement Project conducted 382 surveys with fellow Latinx residents in a county with Latinx growth rates over 1,800% from 1990 to 2014. Among respondents, 58.5% had volunteered in the past year and 47.0% were members of a faith-based or charitable organization. Household income, educational attainment, and English proficiency were most strongly correlated with civic engagement ( r = .456, r = .453, and r = .464, respectively). The main reason for engagement was the betterment of the Latinx community. Main barriers were lack of information (37.1%), limited time (17.2%), disinterest (7.8%), and documentation status (4.3%). Findings can shape conversations about Latinx engagement in ways that include, but go beyond, voting and political representation.

scholarly journals Characterization and transcriptional profiles of Engraulis encrasicolus’ GnRH forms

Reproduction ◽  
2016 ◽  
Vol 152 (6) ◽  
pp. 727-739 ◽  
Author(s):  
Andrea Miccoli ◽  
Ike Olivotto ◽  
Andrea De Felice ◽  
Iole Leonori ◽  
Oliana Carnevali
Keyword(s):  
Physical Environment ◽  
Trophic Ecology ◽  
Open Reading Frames ◽  
Engraulis Encrasicolus ◽  
The Past ◽  
Lack Of Information ◽  
Species Specific ◽  
Reading Frames ◽  
Salmon Gnrh ◽  
Stimulation Of

The European anchovy Engraulis encrasicolus, a member of the Clupeiformes order, holds a great biological and economical importance. In the past, this species was mostly investigated with the aim of assessing its reproductive biology, trophic ecology, population dynamics and the relations existing with the physical environment. At present days, though, an almost complete lack of information afflicts its neuroendocrinology and reproductive physiology. The hypothalamic–pituitary–gonadal (HPG) axis at its highest levels was herein investigated. In this study, the gonadotropin-releasing hormone (GnRH), a neuropeptide underlying many reproduction-related processes, the most critical of which is the stimulation of gonadotropin synthesis and secretion from the pituitary gland, was cloned. Three forms (salmon GnRH, chicken-II GnRH and the species-specific type) were characterized in their full-length open-reading frames and, in accordance with other Clupeiformes species, the distinctive one was found to be the herring-type GnRH. We qualitatively and semiquantitatively evaluated the localizations of expressions and the temporal transcription patterns of the three GnRH forms in male and female specimens throughout their reproductive cycle as well as described their phylogeny with regard to teleost GnRH lineages, and, specifically, to other Clupeiformes species.

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