Mixture Of Dust Research Articles

A nearly terrestrial D/H for comet 67P/Churyumov-Gerasimenko

Cometary comae are a mixture of gas and ice-covered dust. Processing on the surface and in the coma change the composition of ice on dust grains relative to that of the nucleus. As the ice on dust grains sublimates, the local coma composition changes. Rosetta observations of 67P/Churyumov-Gerasimenko previously reported one of the highest D/H values for a comet. However, reanalysis of more than 4000 water isotope measurements over the full mission shows that dust markedly increases local D/H. The isotope ratio measured at a distance from the nucleus where the gas is well mixed is close to terrestrial, like that of other Jupiter family comets. This lower D/H has implications for understanding comet formation and the role of comets in delivering water to Earth.

Lysimachia mauritiana Lam. Extract Alleviates Airway Inflammation Induced by Particulate Matter Plus Diesel Exhaust Particles in Mice

Exposure to air pollution poses a risk to human respiratory health, and a preventive and therapeutic remedy against fine dust-induced respiratory disease is needed. Background/Objectives: The respiratory-protective effects of Lysimachia mauritiana (LM) against airway inflammation were evaluated in a mouse model exposed to a fine dust mixture of diesel exhaust particles and particulate matter with a diameter of less than 10 µm (PM10D). Methods: To induce airway inflammation, PM10D was intranasally injected into BALB/c mice three times a day for 12 days, and LM extracts were given orally once per day. The immune cell subtypes, histopathology, and expression of inflammatory mediators were analyzed from the bronchoalveolar lavage fluid (BALF) and lungs. Results: LM alleviated the accumulation of neutrophils and the number of inflammatory cells in the lungs and the BALF of the PM10D-exposed mice. LM also reduced the release of inflammatory mediators (MIP-2, IL-17, IL-1α, CXCL1, TNF-α, MUC5AC, and TRP receptor channels) in the BALF and lungs. Lung histopathology was used to examine airway inflammation and the accumulation of collagen fibers and inflammatory cells after PM10D exposure and showed that LM administration improved this inflammation. Furthermore, LM extract inhibited the MAPK and NF-κB signaling pathway in the lungs and improved expectoration activity through an increase in phenol red release from the trachea. Conclusions: LM alleviated PM10D-exposed neutrophilic airway inflammation by suppressing MAPK/NF-κB activation. This study indicates that LM extract may be an effective therapeutic agent against inflammatory respiratory diseases.

Geomechanical aspects of stabilizing arsenic trioxide roaster waste in cemented paste backfill at the Giant Mine, Canada

Giant Mine, an abandoned gold mine near Yellowknife in the Northwest Territories of Canada, generated significant arsenic trioxide roaster waste (ATRW) during its operations, posing a substantial environmental hazard. This study explored the feasibility of stabilizing ATRW by incorporating it into cemented paste backfill (CPB). Using response surface methodology (RSM), CPB samples with varying mixing ratios were analyzed to identify key parameters influencing strength. Unconfined compressive strength (UCS) tests assessed physical stability, while saturated hydraulic conductivity and computed tomography (CT) analyses examined the microstructure of the CPB. The results revealed that CPB samples prepared with general use (GU) cement exhibited significantly higher strength than those with a GU and lime kiln dust (LKD) mixture. Binder and solid contents were identified as the most critical factors influencing UCS, with binder content having a more pronounced influence. Curing time was found to be non-significant. Higher binder and solid contents correlated with higher UCS values in the CPB samples. The addition of 10% wt. ATRW reduced the UCS by over 30%, particularly in samples with lower binder and solid contents. Although microstructure differences were not evident in saturated hydraulic conductivity tests, CT scans showed increased formation of high-density arsenic-containing materials in samples with the highest UCS, especially those using GU binder. These findings suggest that optimizing binder and solid contents is crucial for enhancing CPB strength and effectively stabilizing ATRW.

Construction of Energy Consumption Model in Asphalt Mixture Production Stage Based on Field Measurements

To better construct an energy consumption model for the asphalt mixture production stage, this study divides the production process into four phases: aggregate dust removal, aggregate drying, asphalt heating, and mixture blending. Utilizing measured data from various regions in Anhui Province, the model considers factors such as season, mixture type, and energy consumption type. The study quantitatively compares and analyzes the energy consumption results obtained from three calculation methods: the theoretical method, the quota method, and the energy consumption model method. The results indicate that the total energy consumption shares of the aggregate dust removal, aggregate drying, asphalt heating, and mixture blending phases are 4.23%, 69.50%, 17.75%, and 8.52%, respectively. The primary energy consumption during the asphalt mixture production stage is concentrated in the aggregate drying and asphalt heating phases. The energy consumption model based on on-site measurements effectively reflects the actual energy consumption levels during the asphalt mixture production stage. Moreover, the total energy consumption calculated by the three methods follows the order quota method > energy consumption model method > theoretical method. By constructing an energy consumption model based on measured data, it is possible to more accurately assess the energy usage during the asphalt mixture production process. This helps optimize production techniques, reduce energy consumption and carbon emissions, and provide a scientific basis for sustainable road construction.

Experimental investigation of OH* emission spectrum characteristics and transient ignition dynamics in methane and coal dust mixtures explosions

Combustible gases, dusts and their mixtures are widely present in human production and life，and the fire and explosion disasters caused by them pose a serious threat to the field of energy security applications. Studying the ignition process of mixtures is essential for disaster risk assessment and safety protection. In this work, the explosion characteristics and OH* emission spectra of the mixtures were experimentally tested by varying the fuel equivalence ratio ( ER ≈ 0.79 ~ 1.71), and the evolution of the transient flow field structure during the ignition process was quantitatively analyzed using the schlieren image velocimetry method. The results indicate that the emission spectrum of OH* is closely correlated with the maximum explosion pressure, and the spectral intensity of OH* at 306.4nm is consistent with the maximum rate of explosion pressure rise. The flow field during the ignition process of the mixtures shows that a small amount of coal dust (concentration≤30g/m3) can significantly promote flame acceleration and instability as the methane concentration is in lean combustion or stoichiometric ratio. However, when the concentration of coal dust increases (concentration≥40g/m3), coal dust will suppress flame acceleration and instability. For methane concentration in fuel-rich combustion state, coal dust always suppresses flame acceleration and instability. The experimental results contribute to a further understanding of gas and coal dust mixed explosions and provide a verification database for the construction of chemical kinetic mechanisms.

Reactive behaviors and mechanism of methane/coal dust hybrid explosions inhibited by NH4H2PO4 and (NH4)2HPO4: A combined ReaxFF-MD and DFT study

Understanding the explosion-inhibition mechanism of methane/coal dust mixtures at the atomic level is crucial. This study employed ReaxFF-MD and DFT calculations to investigate the inhibitory effects of NH4H2PO4 and (NH4)2HPO4 on methane/coal dust explosions. The research examined macroscopic products, chemical bonds, key reaction pathways, and intermediate products. Furthermore, the evolution mechanism of coal molecules involved in the explosion-inhibition reaction was elucidated. The results indicate that NH4H2PO4 inhibits CO2 generation, while (NH4)2HPO4 enhances H2O production. Additionally, the inhibitors affect not only the initial reaction steps of CH4 but also absorb reactive radicals (•H/•O/•OH) and intermediate products (•CH3/CH2O). Compared to NH4H2PO4, the inhibition cycling reactions of (NH4)2HPO4 exhibit greater diversity. Increasing inhibitors’ mass fraction promotes competing reactions among free radicals, which diminishes the inhibition effect on CH4 dehydrogenation, leading to oscillations in explosion-inhibition efficiency. The inhibitors also delay the bond-breaking time for both the aliphatic bond and the ether-oxygen bridge of coal molecules, thereby prolonging the ring-opening reaction time of these molecules.

Эффективность поверхностного компостирования табачной пыли с использованием микробных смесей

Abstract. Tobacco dust is the main waste in the production of smoking products. The purpose is to study the possibility of tobacco dust utilization by surface composting together with microbial mixtures “Stimiks Kompost”, “Probioks Agro” and “Geostim”, directly in the field conditions, contributing to the restoration of soil fertility. Methods. In the years of research (2020–2021) tobacco dust was applied in doses of 5 and 8 t/ha in pure form and together with microbiological preparations. Scientific novelty. The method of using tobacco production waste as a fertilizer together with microbiological preparations is proposed. Results. It was established that for 30–60 days, tobacco dust application together with destructors, the content of basic nutrient elements in the soil increased: ammonium nitrogen form by 65–207 %, nitrate nitrogen by 83–225 %, available phosphorus by 21–107 %, exchangeable potassium by 80–194 %. Also Increasing of soil biological activity indicators was determined. The process of nitrifying ability of soil increases by 70–194 %, cellulose-destroying activity of microorganisms increases by 27–133 %, the amount of produced CO2 from soil increases by 61–129 %. The content of organic matter (humus) increases up to 4.2–5.5 % for the period of counting (4.0–4.7 % on the reference). Increase of moisture-holding capacity of soils in variants of experiment with tobacco dust and destructors was established (soil moisture for the period of research amounted to 18.4–25.5 %, in control – 17.1–18.7 %). The best results for surface composting of tobacco dust were obtained under wet conditions in 2021 (Hydrothermal coefficient (HTC) = 1.38), in 2020 HTC = 0.87. Mycological analysis revealed a decrease in soil infestation with pathogenic micro-mycetes in the variants of the experiment with tobacco waste. The increase in yield of bitter pepper (variety Baraniy rog) on the background of a mixture of tobacco dust and biodegraders amounted to 12–32 % (2020), seed cucumber (variety Dal’nevostochnyy 27) – 20–33 %.

Effect of large particle mixing on cloud ignition and explosion of fine rice husk

Large particles mixed with fine dust are commonly found in the processing and transportation of grain dust. The mixture of dust is exposed to the risk of dust explosions when suspended in the environment. Using a 20 L spherical explosion device and the dust cloud minimum ignition energy (MIE) experimental platform, this study examines the effects of crushed brown rice mixture on the ignition and explosion of fine rice husk dust. The discovery of large granules of crushed brown rice being lifted up to form flow "obstacles" in the mixed dust cloud has a similar inhibitory effect to inert materials, causing the MIE of the dust cloud to increase from 40 mJ to 150 mJ. However, 5 % of crushed brown rice will lower the 10 mJ dust cloud's ignition energy when the concentration of dust clouds is 500 g/m3. Through testing the dispersibility of mixed dust clouds, it was found that fine dust particles adsorbed on the surface of large particles will peel off after being lifted, improving the dispersibility of the mixed dust cloud and forming a system of mixed dust clouds with finer effective particle size, thereby promoting ignition. Furthermore, due to the improvement in the dispersibility of mixed dust clouds by large particles, at mixing ratios below 30 %, large particles will also significantly increase the maximum rate of pressure rise (dP/dt)max, increasing the likelihood of dust ignition and the consequences of an explosion. Therefore, these findings should be taken into consideration during the process of grain processing and transportation.

Experimental study on characteristics of methane-coal dust explosions and the spatiotemporal evolution of flow field in early flame

To understand the explosion characteristics of methane-lignite coal dust mixtures and the spatiotemporal evolution of the early flame flow field, explosion pressure, OH* emission spectra, and early flame schlieren images were captured in a 60L constant volume combustion bomb. Schlieren image velocimetry was used to obtain the instantaneous velocity distribution of the methane-coal dust flame front. The results indicate that adding coal dust causes a nonlinear increase in explosion pressure, particularly at low methane concentrations. At a 5 % methane concentration, adding coal dust can increase the maximum explosion pressure by up to 39 % (190 kPa). The trend of the OH* emission spectra corresponds with the maximum explosion pressure. A slight increase in coal dust significantly enhances the OH* emission spectra, especially at lower concentrations, potentially increasing it by nearly five times. However, at higher coal dust concentrations, the OH* emission spectra are significantly reduced. Additionally, within the considered concentration range (≤58.14 g/m³), larger turbulent integral length scales in initial conditions consistently result in the fastest flame acceleration. These findings provide experimental evidence for further exploration of the explosion mechanisms of methane-coal dust mixtures and the development of chemical reaction kinetic models.

Variation Law of Hybrid Explosion Characteristic Parameters of Gas and Coal Dust Coupled with Multiple Factors.

This study aims at extensively investigating the explosion characteristics of a hybrid mixture of gas and coal dust. Accordingly, the standard 20 L spherical explosion system was applied to measure parameters such as the lower explosion limit, maximum explosion pressure, and index of the hybrid mixture of different concentrations of gas and coal dust. Moreover, different coal dust particle sizes and components were measured. With regard to coal dust with different particle sizes and components, the obtained results revealed that, while the addition of gas significantly reduced the lower explosion limit, the maximum explosion pressure and index were increased; that is to say, the presence of gas will increase the explosion risk of coal dust. However, under conditions in which the particle size of the coal dust was large or the volatile content was low, the addition of gas was found to lead to a higher decrease of the lower explosion limit; this is, while the maximum explosion pressure and explosion index were increased. Consequently, gas can be argued to have a greater influence on the explosion risk of coal dust with a large particle size or low volatile content. Furthermore, regardless of the particle size or the volatile content of coal dust, the maximum explosion pressure and explosion index of the hybrid mixture were observed to be higher than that of the pure coal dust but lower than that of the pure gas. That is to say, the explosion intensity of the gas/coal dust composite system is higher than that of pure coal dust but less than that of pure gas. The research results can provide theoretical basis for coal mine explosion disaster prevention and control and have important significance.

Exploring the viability of Bentonite-amended blends incorporating marble dust, sand, and fly ash for the creation of an environmentally sustainable landfill liner system

The development of effective and cost-efficient landfill liners is crucial to prevent groundwater contamination from leachate, safeguarding soil quality and the environment. Composite liners, particularly those combining bentonite with supplementary materials such as fly ash or marble dust, present a promising solution. This study delves into a comprehensive investigation of the physical properties of landfill liners composed of bentonite-fly ash and bentonite-marble dust mixtures through an extensive series of laboratory tests. The research systematically analyzes various proportions of bentonite with fly ash and marble dust, evaluating their impact on liner performance in comparison to Bentonite-sand mixtures. Physicochemical analyses are employed to understand the interactions and behaviors of these distinct substances within the amended bentonite. A wide array of physical properties, including Atterberg’s limits, compaction characteristics, free swell index, modified free swell index, California bearing ratio, cohesion, and angle of internal friction, are meticulously examined. Collectively, these properties offer a comprehensive overview of the suitability and performance potential of bentonite-fly ash and bentonite-marble dust mixtures as landfill liners, presenting a viable alternative to traditional bentonite-sand mixtures. The study reveals synergistic effects between bentonite and both fly ash and marble dust, highlighting their significant contributions to enhancing the physical traits of landfill liners. This advancement in landfill liner design holds the promise of effectively mitigating detrimental environmental impacts associated with waste disposal. While this study provides a robust foundation, it is essential for future investigations to prioritize long-term performance assessments and real-world implementation. Validation and fine-tuning of these findings are crucial to ensuring practical applicability and efficacy within authentic landfill construction scenarios. This holistic approach will contribute to the continued evolution and optimization of landfill liner design, addressing the pressing challenges of sustainable waste management and environmental protection.

In vitro mass propagation of Dendrocalamus asper (Giant bamboo) through direct organogenesis

Dendrocalamus asper (giant bamboo) is a clumping type of bamboo belonging to the Poaceae family. Due to its economic and environmental value, demand for this species has increased tremendously. Conventional propagation methods have limitations due to low seed viability and the lack of healthy clumps. Therefore, an in vitro mass propagation protocol was developed to provide healthy plants for large-scale plantations. Seeds were used as the explant and they were surface sterilized and cultured on MS medium free of growth regulators. Nodal segments taken from in vitro germinated seedlings were used for shoot initiation. The best medium for shoot induction (MS medium supplemented with 0.0–2.5 mg/L BAP), best medium for multiple shoot induction (MS medium supplemented with 0.0–5.0 mg/L BAP), effect of shoot cluster size (shoot clusters containing 1–4 shoots) and effect of physical state of the medium (semisolid and liquid media) on multiple shoot induction were determined using shoots per node, mean shoot length and mean number of leaves per shoot after 6 weeks of incubation. Elongated shoots were transferred into a rooting medium and the best medium for root induction (MS medium supplemented with 0.0–5.0 mg/L IBA and IAA) and effect of cluster size (shoot clusters containing 1–4 shoots) on rooting were determined using the number of roots and root length after 6 weeks of incubation. All the cultures were maintained under a 16-hour photoperiod. Well-developed plantlets were transferred to coir pellets and after four weeks transferred into different potting mixtures containing different combinations of sand, compost and coir dust. Unless otherwise mentioned there were at least twenty replicates in all treatments. The highest mean number of shoots per node (16.87±0.52), mean shoot length (4.12±0.27 cm) and mean number of leaves per shoot (4.80±0.33) were observed in the MS medium supplemented with 1.0 mg/L BAP. The MS medium supplemented with 2.0 mg/L BAP was the best for multiple shoot induction, shoot cluster with 3 shoots was the best cluster size and the liquid medium had a better effect on shoot multiplication. The half-strength MS medium supplemented with 2.0 mg/L IBA was the best for in vitro root induction with the highest mean number of roots (7.15±0.77) and a mean root length of 10.79±1.11 cm. Shoot clusters with 3 shoots was the best cluster size for root induction. A sand: compost: coir dust (1:1:1) mixture was the best potting mixture giving 100% survival. These findings provide a reliable micropropagation protocol for D. asper, which holds great promise for meeting the growing demand for bamboo resources and promoting sustainable bamboo cultivation.

Самовоспламенение пылегазовоздушных смесей в атмосфере горных выработок

The underground mining of coal deposits is usually accompanied by manifestation of a number of negative factors, one of which is the presence of dust and gas-air mixtures consisting of fine coal dust, methane released from the broken coal and the air of the mine atmosphere. Despite modern methods and means of dust suppression and dust collection, it has not yet been possible to achieve complete neutralization of dust and gas-air mixtures in the atmosphere of mine workings. The negative effects of dust and gas-air mixtures can manifest themselves in different ways. On the one hand, deposits of coal dust in the worked-out spaces, under certain conditions, form foci of spontaneous combustion, which are the causes of endogenous fires. On the other hand, dust and gas-air mixtures are predisposed to ignition from external sources or to spontaneous ignition followed by combustion in the form of deflagration, which, under certain conditions, turns into detonation, spreading in the atmosphere of mine workings at supersonic speed. This article considers a nonstationary one-dimensional problem of selfignition of dust and gas-air mixtures in the air flows of mine workings. The temperature and the period of spontaneous ignition of dust-gas-air mixtures are found based on the solution of this problem, expressed numerically using the Geer method. An analysis of the mixture self-ignition process is performed and some patterns of the influence of the parameters of mixtures on the period of their self-ignition are revealed.

Polymer composite coatings subjected to sliding wear under simulated lunar temperature and dust conditions

Due to the detrimental effect of lunar dust on tribological components, it is imperative to develop bearing materials and surfaces which can survive and mitigate dust at the interface while operating under lunar environmental conditions. This issue is poised to become more significant in the near future, with lunar exploration evolving beyond the short probing missions of the Apollo era. Therefore, this study aims to investigate the combined effect of temperature and lunar dust on the tribological performance of aromatic thermosetting copolyester (ATSP) and polyether ether ketone (PEEK) -based polymer composite coatings from −150 to 110 °C. The experiments were conducted using a flat pin-on-disk configuration under dry sliding conditions, sliding speed of 0.25 m/s, 17.5 MPa contact pressure, and nitrogen gas environment. It was found that metal-on-polymer coating sliding results in dust embedment and accumulation on the softer material, which yields high friction and two-body abrasive wear. The chemical analysis of transfer film on the metal pin surface indicated a mixture of dust and polymer phases, which increased with increasing temperature, and thus resulted in deteriorated tribological performance. Self-mating polymer coatings yielded lower friction coefficient and wear due to a better dust mitigation resulting in three-body wear at the interface. The ATSP-based coatings showed higher wear resistance at all temperatures, particularly under self-mating sliding condition.

Effects of methane concentration on flame propagation mechanisms and dynamic characteristics of methane/coal dust explosions

The study explores the flame propagation and explosion dynamic behavior of gas/powder two-phase compound explosions, taking methane and coal dust mixture as the research object. The influence of different methane concentrations on the compound explosion characteristics was researched. The vertical pipeline, high-speed camera, ion current probe, and pressure sensor be used to test the propagation behaviors, microstructure characteristics, and explosion dynamics of compound explosion flames. The function of methane concentration on the propagation behaviors, combustion reaction zone thickness, flame temperature, propagation velocity, and explosion pressure of compound flame was revealed, and the propagation mechanisms of gas/powder compound explosion flames were explained. The experimental research discovered that the compound flame of methane/coal dust explosion presents a white luminous zone with uniform distribution and appears to have an approximate homogeneous combustion state. The explosion dynamics parameters all showed a trend of first increased and then decreased as the methane concentration increased, but the reaction zone thickness of the combustion first reduced and then increased. In addition, the dominant position of homogeneous or heterogeneous combustion in the combustion reaction zone will also switch with the change in methane concentration. The compound flame is similar to premixed gas combustion under optimal methane concentration, the combustion zone thickness (δ) and preheating zone thickness (β) are the smallest, and the compound explosion shows powerful performance. In addition, the flame propagation mechanisms of methane/coal dust compound explosion were elucidated based on the theory of heat.

Interactions between aerosols and surface ozone in arid and semi-arid regions of China.

Atmospheric aerosols affect surface ozone concentrations by influencing radiation, but the mechanism and dominant factors are unclear. Therefore, this paper analyses the changes in aerosol-radiative-surface ozone in China's arid and semi-arid regions with the help of the Atmospheric Radiative Transfer (SBDART) model. The results suggest that Aerosol Optical Depth (AOD) and coarse Particulate Matter (PM10) have the same trend, with high values in spring and winter and low values in summer and autumn. Surface ozone is high in spring and summer and low in autumn and winter. Surface ozone is higher in spring and summer and lower in autumn and winter. In winter, mainly secondary pollutants are dominated by high pollution levels. In the rest of the seasons, a mixture of dust, motor vehicle exhaust, and soot is dominated by low pollution levels. Surface ozone is positively correlated with fine particles and negatively correlated with coarse particles. Temperature is positively correlated with surface ozone in all seasons and negatively correlated with PM10 in summer, autumn, and winter. Precipitation negatively correlates with PM10 each season and surface ozone in winter and spring. Analysis of surface ozone and PM10 sources in the more polluted city of Hohhot based on the back-line trajectory model showed that airflow trajectories mainly transported surface ozone and PM10 pollution from northwestern Inner Mongolia and western Mongolia. During dusty solid weather, the decrease in radiation reaching the Earth's surface and the cooling effect of aerosols lead to lower temperatures, which slows down the rate of chemical reactions of precursors of surface ozone, resulting in lower ozone concentrations at the surface. This study can provide a theoretical reference for aerosol and surface ozone control in arid and semi-arid areas of China.

Improved hourly estimate of aerosol optical thickness over Asian land by fusing geostationary satellites Fengyun-4B and Himawari-9

Asian over-land aerosols are complexities due to a mixture of anthropogenic air pollutants and natural dust. The accuracy of the aerosol optical thickness (AOT) retrieved from the satellite is crucial to their application in the aerosol data assimilation system. Fusion of AOTs with high spatiotemporal resolution from next-generation geostationary satellites such as Fengyun-4B (FY-4B) and Himawari-9, provides a new high-quality dataset capturing the aerosol spatiotemporal variability for data assimilation. This study develops a complete fusion algorithm to estimate the optimal AOT over-land in Asia from September 2022 to August 2023 at 10 km × 10 km resolution with high efficiency. The data fusion involves four steps: (1) investigating the spatiotemporal variability of FY-4B AOT within the past 1 h and 12 km radius calculation domain; (2) utilizing the aerosol spatiotemporal variability characteristics to estimate FY-4B pure and hourly merged AOTs; (3) performing bias corrections for FY-4B and Himwari-9 hourly merged AOT for different observation times and seasons considering pixel-level errors for each satellite; (4) fusing the bias-corrected FY-4B and Himawari-9 hourly merged AOT based on maximum-likelihood estimation (MLE) method. Compared to the original FY-4B AOT, validation with AERONET observation confirms that the root mean square error (RMSE) of hourly merged FY-4B AOT decreases by around 40.6 % and the correlation coefficient (CORR) increases by about 27.8 %. Compared to FY-4B and Himawari-9 merged AOT, the fused AOT significantly decreases (increases) RMSE (CORR) by around 24.7 % (7.3 %) and 20.2 % (5.6 %). In addition, fused AOT is double the number of single-sensor merged AOT. Fusion aerosol map accurately describes the spatial and temporal variations in Asian regions controlled by air pollution and dust storms. Further studies are required for other landscapes with different satellite combinations to promote the application in the data assimilation system.

Mineral dust and pedogenesis in the alpine critical zone

Abstract. The influence of mineral dust deposition on soil formation in the mountain critical zone was evaluated at six sites in southwestern North America. Passive samplers collected dust for 2 years, and representative soil and rock were gathered in the vicinity of each dust sampler. All materials (dust, soil, and rock) were analyzed to determine their mineralogy (with X-ray diffraction), geochemistry (with inductively coupled plasma mass spectrometry (ICP-MS)), and radiogenic isotope fingerprint (87Sr/86Sr and εNd). In addition, the grain size distribution of dust and soil samples was determined with laser scattering, and standard soil fertility analysis was conducted on the soil samples. Results reveal that minerals present in the dust but absent in the local bedrock are detectable in the soil. Similarly, the geochemistry and isotopic fingerprint of soil samples are more similar to dust than to local bedrock. End-member mixing models evaluating soil as a mixture of dust and rock suggest that the fine fractions of the sampled soils are dominated by dust deposition, with dust contents approaching 100 %. Dust content is somewhat higher in soils compared to bedrock types more resistant to weathering. These results emphasize the dominant control that mineral dust deposition can exert on pedogenesis in the mountain critical zone.

Effect of Various Methods of Curing on Concrete Using Crusher Dust as Replacement to Natural Sand

AbstractThe present paper highlight upon research work is that curing is one of most important aspect of construction. The life of concrete and its serviceability depends heavily on curing. The method of curing applied on concrete will affect its final strength and durability. Owing to this fact this paper contains the research done on concrete under various curing methods. The standard method of curing concrete is done by water and results wastage of a lot of water. With the increase in the deficiency of availability of water, curing becomes a problem. Hence this research aims at providing better methods of curing which will not only improve the strength and durability of concrete but will also save water. The various methods that have been researched upon are plastic covered curing, addition of sodium silicate to curing water, and addition of curing compounds to curing water. The tests are carried on concrete with desirable strengths of M15 and M20. In this research the fine aggregate used in making of M15 and M20 concrete consists of a mixture of sand and crusher dust. Two mixes of ratio 50:50 and 60:40, sand to crusher dust have been taken and the effects of curing on these mixes are considered. Plastic curing is done by covering the concrete with plastic soon after demolding. Hence minimum water is required. The curing done by sodium silicate is done by adding 2% by weight of sodium silicate to curing water. Concrete is submerged in water containing sodium silicate. Once the concrete is cured, this water mix can be reused to cure freshly cast concrete, thereby saving more water. Curing by curing compounds is done in a similar way as that of curing with sodium silicate, only that instead of sodium silicate, curing compounds are used. The effect of these three methods on concrete is studied and discussions are made.

Briquettes from a Mixture of Cow Menure, Rice Husks and Wood Dust as Alternative Fuel

Briquettes from a Mixture of Cow Menure, Rice Husks and Wood Dust as Alternative Fuel