Large Amounts Of Dust Research Articles

Stretchable Hydrophobic Surfaces and Self-Cleaning Applications

Hydrophobizing of stretchable elastomer surfaces is considered and the reversible behavior of the resulting surface wetting state is examined after stretching and relaxing the hydrophobized samples. The environmental dust are analyzed in terms of elemental constitutes and size, and the dust pinning on the hydrophobized surface is measured. The dust removal mechanisms, by the water droplets on the hydrophobized surface, are investigated. We demonstrated that deposition of functionalized nano-size silica units on the elastomer surface gives rise to hydrophobicity with 135° ± 3° contact angle and low hysteresis of 3° ± 1°. Stretching hydrophobized elastomer surface by 50% (length) reduces the contact angle to 122° ± 3° and enhances the hysteresis to 6° ± 1°. However, relaxing the stretched sample causes exchanging surface wetting state reversibly. Water droplet rolling and sliding can clean the dusty hydrophobized surface almost 95% (mass ratio of the dust particles removed). Droplet puddling causes striations like structures along the droplet path and close examination of the few residues of the dust reveals that the droplet takes away considerably large amount of dust from surface.

Improvement of dedusting efficiency of technological equipment for manufacturing of coloured calcium silicate bricks

The key factors for obtaining coloured calcium silicate bricks is the high degree of dispersion and precise dosage of the colouring matter, as well as its uniform distribution in the silicate mixture. Dust particles of a colour pigment pose the most harmful effect on the health of workers at the industrial shop. In the course of components mixing, a large amount of dust from sand, lime and pigment is released into the working zone air since the process of components mixing implies materials pouring while proportioning as well as vigorous mechanical mixing. For the purpose of the quantitative and qualitative analysis of the working zone air contamination in a components mixing shops, it is necessary to investigate the dust conditions at the shop, the particle size distribution of the mixture components, the concentration of hazardous substances in the working zone air, the aerodynamic properties of dust.

Modelling of ventilation and dust control effects during tunnel construction

A large amount of dust is mainly generated during the construction of the shield tunneling machine. In order to achieve the optimal dust removal effect, this research took the shield section of Jiaozhou North Station of Qingdao Metro Line No. 8 to Jiaodong Airport Station (China) as a case study. For this purpose, the numerical simulation and orthogonal design were undertaken to optimize the parameters of the ventilation and dust removal system for a shield tunneling machine, and to study the influence of each parameter on the dust removal from three aspects, including the distance of pressure tuyere, the air volume of the pressure tuyere, and the distance of the air inlet. The results of the analysis showed that the distance of the pressure tuyere is the main parameter to control the dust removal, and the two other factors had both less influence on the dust removal. The numerical simulation of the optimal method showed that it outperformed on dust removal than the actual working conditions. This research provided a theoretical basis and direction for optimizing the performance of a ventilation and dust removal system.

Preparation and performance of a composite gel as a dust suppressant for coal transportation and storage

ABSTRACTIn the process of coal transportation and storage, a large amount of dust is inevitably generated, which seriously threatens the health of coal miners and causes the waste of resources. How to prevent and control the dust generated during coal transportation and storage is a key issue of coal mine occupational safety research. In this study, sodium alginate is reacted with 2‐acrylamide‐2‐methylpropanesulfonic acid, and the resulting intermediate is graft copolymerized with acrylic acid to prepare an environment friendly dust suppressant product suitable for coal transportation and storage. The microscopic reaction and structure of the product are analyzed by infrared spectroscopy, X‐ray photoelectron spectroscopy, thermogravimetric analysis, and scanning electron microscopy. The optimal synthesis conditions have been obtained by taking the strength of the coking coal as the single factor experiment evaluation index. Through the research on the related properties of the dust suppressant, it is found that this dust suppressant has excellent performance and an obvious dust suppression effect. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47819.

Mergers drive a powerful dusty quasar

Distant Galaxies Massive galaxies in the early Universe host supermassive black holes at their centers. When material falls toward the black hole, it releases energy and is observed as a quasar. Astronomers found a population of powerful distant quasars that are obscured by dust, but it has been unclear how they are formed. Diaz-Santos et al. observed the dust-obscured quasar WISE J224607.56-052634.9 at submillimeter wavelengths, finding three small companion galaxies connected to the quasar by bridges of gas and dust. They inferred that galaxy mergers can provide both the raw material to power a quasar and large quantities of dust to obscure it. Science , this issue p. [1034][1] [1]: /lookup/doi/10.1126/science.aap7605

Determination of dust disperse composition in energy-efficient aspiration systems for building materials production

In various industries, primarily, the production of building materials, technological processes include multiple transfer operations, during which a large amount of dust is released. The resulting dust causes air pollution and various diseases of workers. To prevent this, different dust removing systems are used. One of them is the aspiration system, which includes air purification devices. For the operation of these systems, it is necessary to obtain the data on the disperse composition of dust and its concentration. Since aspiration systems consume a lot of energy, various improvements are used. Here, basing upon the processed experimental data, the authors proposed a method to determine the main parameters of the dust flow, formed in the bulk materials transfer units of energy-efficient aspiration systems.

The Effect of Arctic Dust on the Retrieval of Satellite Derived Sea and Ice Surface Temperatures

Large quantities of dust are transported annually to the Arctic, primarily from Asian deserts. The influx of dust into the polar environment changes the radiative properties of clouds while the deposition of dust onto ice and snow decreases the surface albedo. Atmospheric and surface dust may be identified with space borne radiometers by comparing infrared energy in the 11 μm and 12 μm regime. Between 2007 and 2017 satellite infrared data revealed persistent low-level dust clouds in the vicinity of Amundsen Gulf in the Western Canadian Arctic during the melting season. Evidence suggests that the subsequent deposition of atmospheric dust in the region affected the surface emissivity in the thermal infrared regime. As a result, satellite derived sea and ice surface temperature algorithms were rendered inaccurate in these areas. Moreover, the ubiquitous nature of dust in the region may play a role in the rapidly vanishing cryosphere.

Application of satellite observations in conjunction with aerosol reanalysis to characterize long-range transport of African and Asian dust on air quality in the contiguous U.S.

A methodology utilizing multiple aerosol measurements and reanalysis was developed to analyze the long-range transport (LRT) of North African and Asian dust events and their effect on contiguous U.S. (CONUS) air quality.Two events in 2015, that originated inland from North Africa and Asia, were detected with aerosol optical depth (AOD) greater than 0.8 over the Gulf of Mexico (June 21) and west coast of Oregon and Washington (April 19). Large amounts of dust were rising over Sahara-Sahel and Taklamakan deserts during these events. For the North African dust event, dust remained the dominant aerosol species transporting from North Africa to CONUS. For Asian dust, before the Taklamakan dust outbreak traveled across the Pacific Ocean, it mixed with sulfate from East China and organic carbons from Siberia. The trans-Atlantic North African dust emerged and compressed below 5 km over the Azores High, whereas the trans-Pacific Asian dust entered the westerlies (5–10 km) along with the mid-latitude frontal system.For the two cases examined, the North African dust event tended to have more influence on CONUS air quality. During the LRT periods, there were 4 of 17 rural and suburban stations (with AOD > 0.5 as the LRT dust approached) in Texas and Louisiana reporting PM2.5 daily maximum observations greater than 36.3 μg m−3. In contrast, the Asian dust stayed above ground level, and all of the 4 rural and suburban stations (with AOD > 0.5 as the LRT dust approached) in Washington and Oregon observed daily maximum PM2.5 below 22.4 μg m−3. The integration of measurements and modeling was able to successfully characterize the sources and transport patterns of the LRT dust events, and differentiate their influence on CONUS air quality. Even though there was high AOD from the Asian LRT dust detected over the western CONUS, significant impacts on surface air quality was not observed as the dust remained aloft.

Influence of Pig Farming on the Human Nasal Microbiota: Key Role of Airborne Microbial Communities

ABSTRACTIt has been hypothesized that the environment can influence the composition of the nasal microbiota. However, the direct influence of pig farming on the anterior and posterior nasal microbiota is unknown. Using a cross-sectional design, pig farms (n = 28) were visited in 2014 to 2015, and nasal swabs from 43 pig farmers and 56 pigs, as well as 27 air samples taken in the vicinity of the pig enclosures, were collected. As controls, nasal swabs from 17 cow farmers and 26 non-animal-exposed individuals were also included. Analyses of the microbiota were performed based on 16S rRNA amplicon sequencing and the DADA2 pipeline to define sequence variants (SVs). We found that pig farming is strongly associated with specific microbial signatures (including alpha- and beta-diversity), which are reflected in the microbiota of the human nose. Furthermore, the microbial communities were more similar within the same farm compared to between the different farms, indicating a specific microbiota pattern for each pig farm. In total, there were 82 SVs that occurred significantly more abundantly in samples from pig farms than from cow farmers and nonexposed individuals (i.e., the core pig farm microbiota). Of these, nine SVs were significantly associated with the posterior part of the human nose. The results strongly indicate that pig farming is associated with a distinct human nose microbiota. Finally, the community structures derived by the DADA2 pipeline showed an excellent agreement with the outputs of the mothur pipeline which was revealed by procrustes analyses.IMPORTANCE The knowledge about the influence of animal keeping on the human microbiome is important. Previous research has shown that pets significantly affect the microbial communities of humans. However, the effect of animal farming on the human microbiota is less clear, although it is known that the air at farms and, in particular, at pig farms is charged with large amounts of dust, bacteria, and fungi. In this study, we simultaneously investigated the nasal microbiota of pigs, humans, and the environment at pig farms. We reveal an enormous impact of pig farming on the human nasal microbiota which is far more pronounced compared to cow farming. In addition, we analyzed the airborne microbiota and found significant associations suggesting an animal-human transmission of the microbiota within pig farms. We also reveal that microbial patterns are farm specific, suggesting that the environment influences animals and humans in a similar manner.

The health effects of dust storms in the Southwest United States

Blowing dust events are a common feature of life in West Texas and the SouthwesternUnited States and are increasing in frequency. The composition of inhaled air varies fromregion to region and may include harmful particles, such as particulate matter, bacteria, fungi,and viruses. There are several types of blowing dust events that can be characterized byphysical observations, including the source of dust, the direction of the wind, the density of theparticulate matter, and several other physical parameters. All blowing dust events have thepotential to cause adverse health effects. Inhalation of dust can cause direct respiratory effectsthat range from transient cough to acute fungal infection to acute respiratory failure. Asiandust storms increase all-cause and respiratory disease emergency room visits and pneumoniaadmissions. There is an association between meningococcal meningitis and Saharan duststorm intrusions into West Africa. Haboob (Arabic for strong wind) dust storms stir up largeamounts of dust from the environment and can blow it into densely populated areas. The“haboob lung syndrome” has been reported in patients from West Texas who presented withdusty sputum, sterile cultures, and multilobar infiltrates. Some of these patients requiredadmission to the hospital for acute respiratory failure and mechanical ventilation. Blowing dustevents are a serious public health issue that can be avoided with prevention. Therefore, it isimportant to forecast blowing dust events and to get this information out to the public on dayswith an increase in particulate density. The population can benefit from these warnings bysimply wearing a respirator mask on these days and by avoiding unnecessary trips outside.

An air circulation purifying system based on PLC

Existing air purifiers are mostly indoor air circulation, and most of them cannot achieve indoor and outdoor air circulation and provide fresh air to room. At the same time, the current air purifier filter on the market after absorbing a large amount of dust and other pollutants, if not replaced in time, is likely to cause secondary pollution. In response to these problems, this paper carried out an exploratory research that can achieve indoor and outdoor air purification device. According to the clean air volume of HEPA filter, the pressure of fan and the cross-sectional area of filter are determined, meanwhile, the air resistance of indoor and outdoor circulating air purifier, the effect of air blower on air purification efficiency and filter CADR are discussed in detail. According to the filtering characteristics of single-layer filter, a kind of indoor and outdoor circulating air purifier-single-layer filter type air purifier was designed. Among the air purifier, the PLC control circuit is used to achieve single-layer filter air purifier filter automatically replace.

Smart and energy-efficient dust suction concept for milling of fibre-reinforced plastics

Fibre-reinforced plastic (FRP) are becoming increasingly important in aerospace and premium automotive applications. Usually, the manufacturing of FRP components requires dry machining which generates large quantities of dust. Because of their small size, the dust particles are extremely harmful to machine components and the operator’s physical health. To prevent long-term damage an effective suction system is required. Currently, extraction systems are subsequently integrated into conventional machine tools with no regard to energy efficiency. Hence, this paper introduces the development of an energy-efficient and intelligent dust suction concept for dry machining of FRP. Numerical flow simulations are used to investigate the effectiveness of a central suction as well as local suction at the cutting tool. In order to evaluate the newly developed concept, the amount of extracted particles along with the necessary volumetric flow rates are assessed. The simulation results demonstrate an improved dust particle extraction and an energy saving potential of up to 70%.

Early formation of (super)massive black holes and gravitational waves from their coalescence

Astronomical observations of last few years have presented a surprising evidence that the Universe at redshift of order 10 is densely populated by supermassive black holes (quasars), supernovae, and contains very large amount of dust. All these data are in conflict with the canonical theory of quasar and supernova formation. A model is discussed which in a simple and natural way solves all these problem. In addition it explains an existence of supermassive black holes in each large galaxy and even in small ones. An inverted picture of galaxy formation is suggested when primordial black holes serve as seeds of galaxy formation. Simultaneously the origin and properties of black hole binaries, sources of gravitational waves registered by LIGO are explained. As a by-product the model may lead to abundant cosmological antimatter even in the Galaxy.

Apparent Disk-mass Reduction and Planetisimal Formation in GravitationallyUnstable Disks in Class 0/I Young Stellar Objects

Abstract We investigate the dust structure of gravitationally unstable disks undergoing mass accretion from the envelope, envisioning its application to Class 0/I young stellar objects (YSOs). We find that the dust disk quickly settles into a steady state and that, compared to a disk with interstellar medium (ISM) dust-to-gas mass ratio and micron-sized dust, the dust mass in the steady state decreases by a factor of 1/2 to 1/3, and the dust thermal emission decreases by a factor of 1/3 to 1/5. The latter decrease is caused by dust depletion and opacity decrease owing to dust growth. Our results suggest that the masses of gravitationally unstable disks in Class 0/I YSOs are underestimated by a factor of 1/3 to 1/5 when calculated from the dust thermal emission assuming an ISM dust-to-gas mass ratio and micron-sized dust opacity, and that a larger fraction of disks in Class 0/I YSOs is gravitationally unstable than was previously believed. We also investigate the orbital radius within which planetesimals form via coagulation of porous dust aggregates and show that becomes ∼20 au for a gravitationally unstable disk around a solar mass star. Because increases as the gas surface density increases and a gravitationally unstable disk has maximum gas surface density, is the theoretical maximum radius for planetesimal formation. We suggest that planetesimal formation in the Class 0/I phase is preferable to that in the Class II phase because a large amount of dust is supplied by envelope-to-disk accretion.

A SYSTEMATIC STUDY OF DUST IN EARLY-TYPE GALAXIES WITH AKARI

Early-type galaxies (ETGs) are generally dominated by old low-mass stars, which are not very productive of dust, and hot interstellar plasmas, which are very destructive of dust. Thus ETGs provide harsh environments for survival of dust. It has been found that some ETGs contain a large amount of dust, and yet its supply mechanism is not understood well. We present the result of a systematic study of dust in ETGs with the AKARI mid- and far-infrared all-sky surveys. From the AKARI result and the Ks band data obtained by ground-based telescopes, we find that there is a global correlation between the dust mass and stellar luminosity. We also compare the AKARI all-sky survey result with the CO data to discuss origins of dust in ETGs.

A Massive Shell of Supernova-formed Dust in SNR G54.1+0.3

Abstract While theoretical models of dust condensation predict that most refractory elements produced in core-collapse supernovae (SNe) efficiently condense into dust, a large quantity of dust has so far only been observed in SN 1987A. We present an analysis of observations from the Spitzer Space Telescope, Herschel Space Observatory, Stratospheric Observatory for Infrared Astronomy, and AKARI of the infrared shell surrounding the pulsar wind nebula in the supernova remnant G54.1+0.3. We attribute a distinctive spectral feature at 21 μm to a magnesium silicate grain species that has been invoked in modeling the ejecta-condensed dust in Cas A, which exhibits the same spectral signature. If this species is responsible for producing the observed spectral feature and accounts for a significant fraction of the observed infrared continuum, we find that it would be the dominant constituent of the dust in G54.1+0.3, with possible secondary contributions from other compositions, such as carbon, silicate, or alumina grains. The total mass of SN-formed dust required by this model is at least 0.3 M ⊙. We discuss how these results may be affected by varying dust grain properties and self-consistent grain heating models. The spatial distribution of the dust mass and temperature in G54.1+0.3 confirms the scenario in which the SN-formed dust has not yet been processed by the SN reverse shock and is being heated by stars belonging to a cluster in which the SN progenitor exploded. The dust mass and composition suggest a progenitor mass of 16–27 M ⊙ and imply a high dust condensation efficiency, similar to that found for Cas A and SN 1987A. The study provides another example of significant dust formation in a Type IIP SN explosion and sheds light on the properties of pristine SN-condensed dust.

Analysis of an optical gate device for measuring aeolian sand movement

Abstract Movement of sand in response to wind is the most important feature of aeolian sediment transport on Earth and other planets. Through sand blasting during saltation, large amounts of dust are ejected into the atmosphere and transported long distances, impacting climate and human health. Despite continuing improvements, currently available devices for field measurement of sand movement have limitations. An optical gate device (OGD) for detecting the movement, size, and possibly speed of individual sand grains during aeolian sediment transport was analyzed. The approach uses the highly time resolved signal from these sensors, which consist of a light emitter and a photosensitive sensor. A specific OGD that is manufactured by Optek (Carrollton, Texas, USA) was tested in a sediment transport wind tunnel alongside trap-style devices. The OGD device provided particle counts and total signal response that were well correlated with sand trap data (R2 between 0.66 and 0.88). Inter-comparison among eight identical units of the OGD showed excellent repeatability (R2 > 0.98 for 7 of 8 units). Subsequent tests revealed that the response of the phototransistor (light sensor) can be linear when operated within certain workable limits. Practical implications of this are that there is potential for extracting size distribution information. Limits imposed by noise levels in the signal and interferences from extraneous light sources were also identified. Despite the results presented being specific to the OGD model tested, much of the approach outlined is applicable to any OGD-type device (including Wenglor®) if the signal of the photo detector can be accessed directly.

Evaluating the Impact of Atmospheric Depositions on Springtime Dinitrogen Fixation in the Cretan Sea (Eastern Mediterranean)—A Mesocosm Approach

Large amounts of dust and atmospheric aerosols, originating from surrounding desert areas (e.g., Sahara and Middle East) are deposited annually on the surface of the Eastern Mediterranean Sea. These depositions can provide high amounts of micro (such as Fe, Zn, Co) and macro nutrients (such as P and N) to supplement nutrient-poor surface waters- that typically limit primary productivity and also dinitrogen (N2) fixation in many marine environments. Here, we studied the impact of the atmospheric deposition of dust and aerosols on N2 fixation in the Cretan Sea (Eastern Mediterranean Sea). Mixed polluted aerosols (hereafter A) and Saharan dust (hereafter SD) were added to nine mesocosms (3-m3 each) containing surface mixed layer seawater (~10 m), and N2 fixation was evaluated for 6 days during May 2012 (springtime). The addition of SD triggered a rapid (30 h) and robust (2-4 fold) increase in N2 fixation rates that remained high for 6 days and contributed 3-8% of the primary productivity. The A addition also resulted in higher N2 fixation rates compared to the unamended control mesocosms, although the responses were less profound (1.5-2 fold) and accounted for only 2-4% of the primary productivity. The microbial community responded differently to the two additions. Heterotrophic bacterial N2 fixers dominated the diazotroph community in A and the control mesocosms, while the non-filamentous cyanobacterial group Trichodesmium prevailed in the SD treatment (68% of all the operational taxonomic units, verified by qPCR analyses). Our results indicate that the aerosol source, its route prior to deposition, and its specific chemical composition, can alter the diazotrophic diversity and activity in the Eastern Mediterranean Sea and may thus impact both the N and C dynamics in this impoverished environment.

Spectral energy distribution simulations of a possible ring structure around the young, red brown dwarf G 196-3 B

The origin of the very red optical and infrared colours of intermediate-age ($\sim$10 - 500 Myr) L-type dwarfs remains unknown. It has been suggested that low-gravity atmospheres containing large amounts of dust may account for the observed reddish nature. We explored an alternative scenario by simulating protoplanetary and debris discs around G196-3B, which is an L3 young brown dwarf with a mass of $\sim 15$ $M_{\rm Jup}$ and an age in the interval 20 - 300 Myr. The best-fit solution to G196-3B's photometric spectral energy distribution from optical wavelengths through 24 $\mu$m corresponds to the combination of an unreddened L3 atmosphere ($T_{\rm eff} \approx 1870$~K) and a warm ($\approx$ 1280 K), narrow ($\approx$ 0.07 - 0.11 R$_{\odot}$) debris disc located at very close distances ($\approx$ 0.12 - 0.20 R$_{\odot}$) from the central brown dwarf. This putative, optically thick, dusty belt, whose presence is compatible with the relatively young system age, would have a mass $\ge 7\times 10^{-10}$ M$_{\oplus}$ comprised of sub-micron/micron characteristic dusty particles with temperatures close to the sublimation threshold of silicates. Considering the derived global properties of the belt and the disc-to-brown dwarf mass ratio, the dusty ring around G196-3B may resemble the rings of Neptune and Jupiter, except for its high temperature and thick vertical height ($\approx 6 \times 10^3$ km). Our inferred debris disc model is able to reproduce G196-3B's spectral energy distribution to a satisfactory level of achievement.

Characterisation of dusts from cement plants with respect to parameters relevant for storage and transport

In cement plants, large amounts of dust are generated and these have to be separated from various off-gases before discharge. The physical and flow properties of these dusts are important for the design and operation of the dust separation process and handling and storage facilities. In this study, five cement kiln dusts and three dusts from other sources in cement production were investigated. Shear tests showed that the flowability of most dust is very poor. Furthermore, the flowability depends on the consolidation stress: the higher the consolidation stress, the better the flowability. Three flowability indicators – the angle of repose, the Hausner ratio and Carr's compressibility – were also determined, but these indicators produced very inconsistent results. In most cases, the flowability of the dust was overestimated. Therefore, shear tests are strongly recommended for reliable categorisation of the flowability of dusts from cement plants.