Chalk Dust Research Articles

Heightened sensitivity in high-grooming honey bees (Hymenoptera: Apidae).

Honey bees use grooming to defend against the devastating parasite Varroa destructor Anderson and Trueman. We observed the grooming responses of individual bees from colonies previously chosen for high- and low-grooming behavior using a combination of mite mortality and mite damage. Our aim was to gain insight into specific aspects of grooming behavior to compare if high-grooming bees could discriminate between a standardized stimulus (chalk dust) and a stimulus of live Varroa mites and if bees from high-grooming colonies had greater sensitivity across different body regions than bees from low-grooming colonies. We hypothesized that individuals from high-grooming colonies would be more sensitive to both stimuli than bees from low-grooming colonies across different body regions and that bees would have a greater response to Varroa than a standardized irritant (chalk dust). Individuals from high-grooming colonies responded with longer bouts of intense grooming when either stimulus was applied to the head or thorax, compared to sham-stimulated controls, while bees from low-grooming colonies showed no differences between stimulated and sham-stimulated bees. Further, high-grooming bees from colonies with high mite damage exhibited greater grooming to Varroa than high-grooming colonies with only moderate mite damage rates. This study provides new insights into Varroa-specific aspects of grooming, showing that although a standardized stimulus (chalk dust) may be used to assess general grooming ability in individual bee grooming assays, it does not capture the same range of responses as a stimulus of Varroa. Thus, continuing to use Varroa mites in grooming assays should help select colonies with more precise sensitivity to Varroa.

Preliminary Study and Use of Design of Dusto Cleaner for Black Board

Even if we lead to the digital platform traditional chalk and board is an integral part of the education life. Blackboards and chalk pieces are used in almost every educational field in the world. Cleaning the board using a duster is essential for continuing the writing process and this involves rubbing a sponge surface against the board surface. This cleans the board but also creates a fine dispersion and particles of chalk powder around the atmosphere nearer the board, which is certain to be inhaled by the teachers, and in many cases, students who occupy seats near the blackboard suffer some inhalation problems. The work also stated that teachers were at the maximum risk of inhaling the chalk dust and may suffer from respiratory diseases. Key Words: Blackboard, chalk, duster, respiratory, diseases

Superhydrophobic and easy-to-clean full-packing nanopatterned microlens array with high-quality imaging.

The high-quality imaging and easy cleaning property of microlens array (MLA) are two very important factors for its outdoor work. Herein, a superhydrophobic and easy-to-clean full-packing nanopatterned MLA with high-quality imaging is prepared by thermal reflow together with sputter deposition. Scanning electronic microscopy (SEM) images demonstrate that the sputter deposition method can improve 84% packing density of MLA prepared by thermal reflow to 100% and add nanopattern on the surface of microlens. The prepared full-packing nanopatterned MLA (npMLA) possess clear imaging with a significant increase of signal-to-noise ratio and higher transparency compared with the MLA prepared by thermal reflow. Besides for excellent optical properties, the full-packing surface displays a superhydrophobic property with a contact angle of 151.3°. Further, the full-packing contaminated by chalk dust become easier to be cleaned by nitrogen blowing and deionized water. As a result, the prepared full-packing is considered to be potential for various applications in the outdoor.

Prevalence and risk factors of chronic respiratory symptoms in public and private school teachers in north-western Ethiopia: results from a multicentre cross-sectional study

ObjectiveThis study aimed to investigate the prevalence and risk factors of chronic respiratory symptoms among school teachers in Gondar city, north-western Ethiopia.DesignA school-based cross-sectional study was conducted from April to...

DIDR - Design and Implementation of a Dust Remover from a Conventional Blackboard Duster to Prevent Respiratory Problems

The idea behind the project is to create a device that can be used to dust a blackboard duster. In other words, ingesting a piece of black blackboard chalk won't kill you, but breathing in the dust over an extended period of time might cause or worsen respiratory issues. Thus, it is essential to have the capability of automated cleaning the duster as well as the capability of collecting the dust in order to prevent the release of airborne dust that poses health risks. The principles of "product design and development" have been used in the creation of this product. A machine with greater performance was required due to the advancement of technology in order to meet market and human demands. Because of its potential usage, this project was selected to simplify human labour and reduce the need for human power. A solution that will make it easier to clean and help with appropriate disposal of chalk dust has been created as part of the endeavour to eradicate the dust.

Electrodeless Nanogenerator for Dust Recover

Triboelectric nanogenerator (TENG) has the advantages of low cost, low weight, simple structure, and high efficiency. It is a promising low‐frequency mechanical energy capture technology, which shows great potential in dealing with energy and environmental crisis and promoting new electronic products. TENGs have demonstrated irreplaceable design freedom over traditional electronic devices, including its ability to work independently of electrodes. In fact, the displacement current is an unreal current, it can work independently without electrodes. Moreover, due to the lack of “shielding effect” of the electrode, the surface potential can be larger than devices worked with electrodes. Here, based on TENG's high‐voltage characteristic without electrode, the application of dust removal is explored, and a kind of electrodeless polyethylene triboelectric blackboard eraser was demonstrated as an example, which can effectively restrain the flying of chalk dust (limit the dust diffusion within 0.648 m). The electrostatic charge decayed blackboard eraser can be recharged by the electrodeless TENG without requirement of electrodes establishment. In fact, contact electrification may happen frequently in natural environment, and further design may be achieved without the limitation of electrodes.

A preliminary study on the effect of chalk dust on human health0

The chalk used in educational institutions is of two types, dusting chalk and non-dusting chalk. The regular dusting chalk produces a finer and lighter dust, which is more likely to linger in the air and be breathed in. Non-dusting chalks produce a heavier dust that is less likely to linger in the air. In most of the cases, a lot of the dust is heavier and do not tend fly at all. It is very similar to the regular dusting chalk and still creates dust. The ultimate difference lies in the fact how fine the dust is. Since the dusting chalk paves the way for many allergies this was becoming a problem. But on the other hand, the non-dusting chalks have more chemical composition when compared to dusting chalk. As both the chalks have different compositions, they have their own effect on human health. The present study explores human exposure to the harmful dust when chalk is used for teaching. In this study, a preliminary attempt was made to observe the varied responses of people of various age groups to share their responses on the effects of chalk in their lives through a structured survey. Various health issues caused were reported based upon the dust they were exposed to and concluded accordingly

Preparation and Evaluation of PDMS/Carbon Soot Particles Superhydrophobic Biomimetic Composite Coating with Self-Cleaning and Durability.

In this paper, a superhydrophobic biomimetic composite coating was fabricated on brass by electrochemical etching, brushing PDMS adhesive layer, and depositing carbon soot particles. Due to the microstructure and the optimized ratio of PDMS, the contact angle of the superhydrophobic coating is up to 164° and the sliding angle is only 5°. The results of optical microscopy and morphometric laser confocal microscopy show that the prepared coating surface has a rough hierarchical structure. A high-speed digital camera recorded the droplet bouncing process on the surface of the superhydrophobic coating. The self-cleaning property of the coatings was evaluated by applying chalk dust particles as simulated solid contaminants and different kinds of liquids (including grape juice, beer, cola, and blue ink) as liquid contaminants. The coating remained superhydrophobic after physical and chemical damage tests. This work presents a strategy for fabricating superhydrophobic biomimetic composite coatings with significant self-cleaning properties, durability, and shows great potential for practical engineering applications.

Preparation of TiO2 Superhydrophobic Composite Coating and Studies on Corrosion Resistance.

The superhydrophobic coatings with excellent performance are prepared on the brass substrate to improve its application limitations in real production. In this article, the superhydrophobicity was obtained by the modification of TiO2 nanoparticles, and the FAS/STA-TiO2 superhydrophobic coating of the composite structure was obtained by modification of 1, 1, 2H, 2H-perfluoroquine trimethyl silane (FAS). By using scanning electron microscopes (SEMs), X-ray spectrometers (EDSs), and Fourier transform infrared (FTIR) spectrometers, the surface morphology, chemical composition, and functional group structure of the samples were analyzed in turn. Experiments show that the water contact angle of the FAS-modified STA-TiO2 coating reaches 161.3°, and the sliding angle is close to 1.2°. Based on the chalk dust containment, it has enabled noticeable self-cleaning properties. The composite superhydrophobic coating also presents enhanced adhesive strength compared with the single coating by the tape peeling experiment. Moreover, the composite coating has a corrosion current density as low as 8.41 × 10-7 A/cm2, and the largest |Z| in low frequency in a 3.5% NaCl solution to achieve better protection of the brass substrate. It is also not difficult to see that FAS/STA-TiO2 coating can not only improve the corrosion resistance of brass substrates but also be applied to other metal substrates.

The Brown Commons in the Time of Pandemic

The Brown Commons in the Time of Pandemic

Влияние адгезии на трение качения и скольжения: эксперимент

Normal and tangential contact between a cylindrical steel indenter (wheel) and an elastomer with high adhesive properties is investigated. In the case of indentation in the normal direction, a computer simulation of the process of indentation and detachment was carried out, which shows good coincidence with an experiment. For the rolling friction mode, when analyzing the measured dependences of the tangential component of the contact force on the wheel displacement, the adhesive component of the friction force was determined. The situation of sliding friction, in which the rotation of the wheel was impossible, is considered. In the presence of adhesion, the sliding friction force is proportional to the contact area. In the absence of adhesion (the elastomer is covered with a chalk dust), a stick-slip friction mode is realized. The frequency and amplitude of stick-slip transitions depend on the indentation depth of the indenter into the elastomer.

Dust Deposition’s Effect on Solar Photovoltaic Module Performance: An Experimental Study in India’s Tropical Region

A solar PV panel works with maximum efficiency only when it is operated around its optimum operating point or maximum power point. Unfortunately, the performance of the solar cell is affected by several factors like sun direction, solar irradiance, dust accumulation, module temperature, as well as the load on the system. Dust deposition is one of the most prominent factors that influence the performance of solar panels. Because the solar panel is exposed to the atmosphere, dust will accumulate on its surface, reducing the quantity of sunlight reaching the solar cell and diminishing output. In the proposed work, a detailed investigation of the performance of solar PV modules is carried out under the tropical climatic condition of Chennai, India, where the presence of dust particles is very high. The data corresponding to four different dust samples of various densities at four solar irradiation levels of 220, 525, 702, and 905 W/m2 are collected, and performance analysis is carried out. Based on the analysis carried out, the maximum power loss is found to be 73.51%, 66.29%, 65.46%, and 61.42%, for coal, sand, brick powder, and chalk dust respectively. Hence, it can be said that coal dust contributes to the maximum power loss among all four dust samples. Due to heat dissipation produced by dust deposition, the performance of solar PV modules is degraded as the temperature rose.

An effective approach to fabricate the corrosion resistance of superhydrophobic ZnO/Ni composite coating on carbon steel substrate

In this study, the carbon steel substrates were coated with nickel (Ni), zinc oxide (ZnO) and ZnO/Ni coatings by electrodeposition approach and modified with stearic acid (STA)-ethanol solution to obtain STA-Ni, STA-ZnO and STA-ZnO/Ni coatings, respectively. The surface morphologies, chemical compositions and surface roughnesses of the modified coatings were characterized by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and confocal laser scanning microscope (CLSM), respectively. The wettability tests shows that the water contact angle (WCA) of the modified coatings with micro/nanostructure are all greater than 150° and the sliding angle (SA) are all less than 10°, especially the STA-ZnO/Ni coating with a WCA of 164.3° and a SA of 2.3°, displaying the prominent superhydrophobicity. Interestingly, the three modified coatings all exhibited excellent mechanical stabilities and self-cleaning properties after being scratched by a knife blade, peeled off by adhesive tape, abrased by sandpaper, and contaminated by chalk dust. Moreover, the corrosion resistance tests confirms that the STA-ZnO/Ni superhydrophobic coating possess higher durability and anticorrosion performance than that of STA-ZnO and STA-Ni coatings. The superhydrophobic STA-ZnO/Ni composite coating prepared by two-step electrodeposition combined with low surface energy material modification designed in this work shows great potential and prospect in industrial application.

Detection and Erasing Scribble Blackboard System Based on Hough-Transform Method Using Camera

Teachers of a secondary school in Semarang city are often exposed to blackboard chalk dust. This will give a significant impact if it occurs at a fairly frequent intensity and a long period of time. An automatic scratch detector and designing a device that can erase the blackboard is a preventive step that can reduce the long-term impact of chalk dust. The scratch detector uses a circle shape parameter as a mark of dirty position that needs to be erased. Light can affect the system performance. The system works properly at light intensities ranging from ± 160 to ± 200 lux. Testing the threshold value proves that the system can detect circles in the range of 40 - 55. The pixel size which is detected by the camera was 640x480 will allow the system to divide the blackboard into 9 mapping areas. The mapping area is differentiated into 9 sections so that the x and y coordinate positions of the blackboard dirty spot can be determined. A mechanical execution will erase the top and bottom areas according to the position of the detected mapping area. The success of scratch detector reaches 81.8%..

The American Short Story and Me

The American Short Story and Me

Occupational exposure to particulate matter during blackboard teaching and its deposition in the airways of human lungs.

This study aims to estimate the teachers' exposure to particulate matter (PM) during a chalk and talk class considering various exposure conditions and to determine the deposition pattern of PM in human airways. The study was carried out in three steps, viz., questionnaire survey, exposure measurement, and dosage calculation. Exposure to chalk dust during teaching was measured for 40 teachers in terms of PM of different size range (PM 10, PM 2.5, and PM 1) while using different brands of chalks. Deposition in lungs was determined using Multiple Path Dosimetry model for four subject categories, viz., adult men, elderly men, adult women, and elderly women. The average exposure during teaching activity was 498, 85, and 30µg/m3 of PM 10, PM 2.5, and PM 1, respectively. Chalks which are made of calcium carbonate with high density of packing emitted lesser PM 10. Results showed no significant difference in the exposure to PM by teachers while writing at different relative heights of the board. The highest total deposition of PM in lung was observed for elderly women. The deposited mass per unit area was the highest for adult women in all the three sizes of PM. This study showed that there was no significant difference in exposure to PM while using normal and dustless chalks. The exposure level suggests that there is a strong need to either shift to smart classes or to improve the technology in chalk production in such a way that it produces less dust and limit the exposure to teaching professionals.

Effect of Exposure to Airborne Chalk Dust Particles on Students’ Respiratory Function

The use and reuse function of chalkboard produces chalk dust particles in the classroom entering into the classroom occupants’ respiratory system through their mouths and nasopharyngeal regions while talking or breathing. The potential impact of dust particles of the respiratory system includes airflow resistance, lung volumes impairment and lung damage. This study measured the expired volume of air from the lungs during a guided maximal expiration to determine the effect of chalk dust particles on the ultimate lung function in the classroom. The sociodemographic characteristics of the participants were assessed using oral interview while the assessment of the anthropometric data and the participants’ lung function indices was done through the use of a stadiometer and digital spirometer, respectively. This study employed a quasiexperimental research design. It involved the exposed (n = 120) and control (n = 120) groups selected from classrooms where chalkboards and marker boards were used, respectively. The results revealed that among the lung functions indices investigated, there were statistical significant differences between the exposed and the control groups in FEV1 (%) (0.002), PEFR (L/s) (0.000), FEF25 (L/s) (0.000) FEF75 (L/s) (0.000), FEF25-75 (L/s) (0.000), FEV1 (%) (0.002) but no significant differences in FEV1 (0.135), FVC (0.493) and FVC (L) (0.506). Therefore, chalk dust particles from chalkboard usage had a negative effect on the respiratory function (lung function indices) in the classrooms.

Canaries at the Climbing Wall: A Comparative Study of Particulate Matter at Two University Climbing Walls

Magnesium alba—chalk—is regularly applied by indoor and outdoor climbers to their hands to reduce sweat while climbing in order to grip climbing holds. We investigated the potential for suspended chalk dust to lead to unhealthy levels of indoor particulate matter (PM2.5 and PM10) in two university climbing facilities. Low-cost, Dylos DC 1700 PM monitors sampled air quality during two, 5-day sampling periods. Findings revealed “good” PM values at one university climbing facility and “unhealthy” (PM2.5) or “very unhealthy” (PM10) values at the other institution’s climbing wall. Facility predicted over 60% of the variance in PM readings, and post hoc tests revealed 75% of the variance in PM values at the second institution can be explained by open climbing hours. These findings hold a variety of implications for future research and management of university climbing wall facilities to ensure the health of staff and their patrons.

Heavy metals analysis in chalk sticks based on ICP-AES and their associated health risk.

The purpose of this study was to determine the contents of 12 metals in obtainable chalk sticks and assess their associated health risk. Chalk stick samples from 16 factories were analyzed by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The results showed that 12 metals were detectable in white and colored chalks. The contents of Al, Fe, and Mg were in the range of 646.2-3909μg/g, 408.8-2075.1μg/g, and 125-6825.7μg/g, respectively. Additionally, the levels of Cu, Pb, Mn, and Cr were ranked in the order of Cu>Cr>Pb>Mn, while the maximum levels of As, Ni, Cd, and Sn in all samples (9.90, 10.14, 7.27, and 6.08μg/g, respectively) were relatively lower than those of other metals. Furthermore, the cumulative hazard index (HI) values of all metals and carcinogenic risk (CR) of As (1.12E-4), Ni (1.39E-4), and Cr (1.15E-4) for children were also higher than the threshold value (1.0E-6 to 1.0E-4), suggesting that chalk dust particles may exert adverse effects on children.

Eco-friendly fabrication of superhydrophobic surface with anti-corrosion by transferring dendrite-like structures to aluminum substrate

The superhydrophobic surface was successful fabricated through spin-coating epoxy resin firstly and transferring the dendrite-like structures to aluminum substrate coated with epoxy resin. The combination of organic coating and superhydrophobic surface with dendritic micro-nano structures prevent the permeation of corrosive ions more effectively. The results indicated the fabricated superhydrophobic surfaces possessed a WCA and WSA of nearly 154° and 0°, exhibiting good superhydrophobicity. Besides, the superhydrophobic surface displayed an excellent repellency to acidic or alkaline droplets. The self-cleaning performance of the superhydrophobic surface against fine sand and chalk dust was also proved. Moreover, the anti-corrosion property of superhydrophobic surface has greatly improved due to the dual function of epoxy resin and the air pockets trapped in superhydrophobic surface. This eco-friendly and facile approach provides a novel strategy to prevent metal from corrosion, which will promote the application of superhydrophobic surface in metal protection field.