Measurement report: Particle-size-dependent fluorescence properties of water-soluble organic compounds (WSOCs) and their atmospheric implications for the aging of WSOCs

Water-soluble organic compounds (WSOCs) play important roles in atmospheric particle formation, migration, and transformation processes. Size-segregated atmospheric particles were collected in a rural area of Beijing. Three-dimensional fluorescence spectroscopy was used to investigate the optical properties of WSOCs as a means of inferring information about their atmospheric sources. Sophisticated analysis on fluorescence data was performed to characteristically estimate the connections among particles of different sizes. WSOC concentrations and the average fluorescence intensity (AFI) showed a monomodal distribution in winter and a bimodal distribution in summer, with the dominant mode in the 0.26–0.44 µm size range in both seasons. The excitation–emission matrix (EEM) spectra of WSOCs varied with particle size, likely due to changing sources and/or the chemical transformation of organics. Size distributions of the fluorescence regional integration (regions III and V) and humification index (HIX) indicate that the humification degree or aromaticity of WSOCs was the highest in the particle size range of 0.26–0.44 µm. The Stokes shift (SS) and the harmonic mean of the excitation and emission wavelengths (WH) reflected that π-conjugated systems were high in the same particle size range. The parallel factor analysis (PARAFAC) results showed that humic-like substances were abundant in fine particles (< 1 µm) and peaked at 0.26–0.44 µm. All evidence supported the fact that the humification degree of WSOCs increased with particle size in the submicron mode (< 0.44 µm) and then decreased gradually with particle size, which implied that the condensation of organics occurred in submicron particles, resulting in the highest degree of humification in the particle size range of 0.26–0.44 µm rather than in the < 0.26 µm range. Synthetically analyzing three-dimensional fluorescence data could efficiently reveal the secondary transformation processes of WSOCs.

Study on the cleaning effect of atomized droplets on the aero-engine

The aero-engine will produce fouling during operation, which will affect the engine performance. On-line cleaning can effectively remove fouling, in order to solve the problem of the poor cleaning effect for aero-engine on-wing cleaning and carry out numerical simulation of the on-line cleaning process. The discrete phase model is used to optimize the particle size and mass flow of the cleaning fluid. The erosion rate and vorticity of the droplets on the blade surface are used as the effect target to simulate and optimize the cleaning process parameters to obtain a better particle size range and the ratio of cleaning fluid to air mass flow. Through the evaluation of the cleaning process parameters of the aero-engine on-wing cleaning test and the analysis of the engine exhaust temperature margin (EGTM) data, it is concluded that the cleaning effect is improved by nearly 40%.

Influence of Particle Size of River Sand on the Decontamination Process in the Slow Sand Filter Treatment of Micro-Polluted Water

Slow sand filters (SSFs) have been widely used in the construction of water plants in rural areas. It is necessary to find river sand of suitable particle size to improve SSF treatment of micro-polluted water so as to ensure the effective and long-term operation of these plants. In this study, SSF1# (particle size of 0.1–0.5 mm), SSF2# (particle size of 0.5–1 mm), and SSF3# (particle size of 1–1.5 mm) were selected. The physical absorption, CODMn and NH4+-N removal effect, and microbial community were analyzed. According to Langmuir and Freundlich adsorption model fitting, the smaller the particle size of the river sand, the more pollutants are adsorbed under the same conditions. SSF1# has the shortest membrane-forming time, highest CODMn and NH4+-N removal rate, and highest Shannon estimator, indicating that there are more abundant microbial species in the biofilm. Mesorhizobium, Pannonibacter, Pseudoxanthomonas, Aquabacterium, Devosia, and other bacteria have different proportions in each system, each forming its own stable biological chain system. The effluent quality of the three SSFs can meet drinking water standards. However, river sand with a particle size range of 0.1–0.5 mm is easily blocked, and thus the recommended size range for SSF is 0.5–1 mm.

Effective Removing of Light Impurities from an Aggregate in SEL Separator

The aim of the paper is a work characteristics of innovative technological circuit for production and beneficiation of minerals aggregates. Investigative programme included separation of chalcedonite aggregate with particle size range 2-4 mm, 2-8 mm and 8-16 mm,upstream separated into regular and irregular particles. Tests were conducted in a dedicated separation device of light fractions (SEL)constructed in in HTS Gliwice, within the frames of “Formator Puls” project.

Identification of rare-earth minerals associated to K-feldspar: Capacsaya project in Peru

A recently discovered the rare-earth-rich site in Capacsaya, located at 123 km northwest of Cusco, at the south of Peru, contains significant quantities of light and heavy rare-earth elements such as neodymium, lanthanum, cerium, europium, and yttrium. This work reports the identification of rare-earth elements and their associated minerals using scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction analyses. Five (5) samples extracted from different locations at the Capacsaya site were characterized and identified K-feldspar as the mineral associated with the rare-earth elements in a representative sample with a high concentration of lanthanum and cerium. The results showed rare-earth elements contained within the mineral phase monazite, being cerium the dominant element in the phase (La, Ce, Nd)PO$$_4$$ 4 . Finally, through the electrostatic separation process we demonstrate that it was possible to achieve an efficient separation of the K-feldspar phase in the particle size range 75–150 $$\upmu$$ μ m.

Indoor Air Pollution Effects On Pediatric Asthma Are Submicron Aerosol Particles Dependent

The school environment is crucial for the child’s health and wellbeing. On the other hand, the data about the role of school’s aerosol pollution on the etiology of chronic non-communicable diseases remain scarce.Objectives: To evaluate the level of indoor aerosol pollution in primary schools and its relation to the incidence of doctor’s diagnosed asthma among younger school-age children.Methods: The cross-sectional study was carried out in 11 primary schools of Vilnius during one year of education from autumn 2017 to spring 2018. Particle number (PNC) and mass (PMC) concentrations in the size range of 0.3-10 µm were measured using an Optical Particle Sizer (OPS, TSI model 3330). The annual incidence of doctor’s diagnosed asthma in each school was calculated retrospectively from the data of medical records.Results: The total number of 6-11 years old children participated in the study was 3638. The incidence of asthma per school ranged from 1.8 to 6.0%. Mean indoor air pollution based on measurements in classrooms during the lessons was calculated for each school. Levels of PNC and PMC in schools ranged between 33.0-168.0 part/cm 3 and 1.7-6.8 µg/m 3 , respectively. There was a statistically significant correlation between the incidence of asthma and PNC as well as asthma and PMC in the particle size range of 0.3-1 µm (r=0.66, p=0.028) and (r=0.71, p=0.017) respectively. No significant correlation was found between asthma incidence and indoor air pollution in the particle size range of 0.3-2.5 and 0.3-10 µm.Conclusions: We concluded that the number and mass concentrations of indoor air aerosol pollution in primary schools in the particle size range of 0.3-1 μm are primarily associated with the incidence of doctor’s diagnosed asthma among younger school age-children.

Application of spruce wood flour as a cellulosic-based wood additive for recycled paper applications— A pilot paper machine study

This study gives a first insight into the use of wood flour as a plant-based and cellulosic-based alter-native additive for newsprint and paperboard production using 100% recycled fibers as a raw material. The study compares four varieties of a spruce wood flour product serving as cellulosic-based additives at addition rates of 2%, 4%, and 6% during operation of a 12-in. laboratory pilot paper machine. Strength properties of the produced newsprint and linerboard products were analyzed. Results suggested that spruce wood flour as a cellulosic-based additive represents a promising approach for improving physical properties of paper and linerboard products made from 100% recycled fiber content. This study shows that wood flour pretreated with a plant-based polysaccharide and untreated spruce wood flour product with a particle size range of 20 μm to 40 μm and 40 μm to 70 μm can increase the bulk and tensile properties in newsprint and linerboard applications.

Isolation, Characterization and Quantitation of Photoactive phases of Titanium (IV) oxide in skin-lightening products

Titanium (IV) oxide (TiO2) is used as a physical blocker of ultraviolet (UV) radiation in many skin-care products. Absorption of TiO2 through the skin is likely to interact with viable tissues because UV radiation absorption generates toxic reactive oxygen species such as hydroxyl radicals. Studies on the acute toxicity of TiO2 nanoparticles in mammals indicate that intra-tracheal instillation, intraperitoneal injection or oral instillation of TiO2 particles to the animals evoke an inflammatory response as well as certain histopathological changes. Ultrafine particles of the anatase form of titanium (IV) oxide, which are smaller than 0.1 microns, are pathogenic. In this work eight skin-lighteners containing TiO2 from South African market were studied. The TiO2 was extracted by a fusion technique and quantified by inductively coupled plasma-optical emission spectrometry (ICP-OES). Sequential solvent extraction was employed to isolate TiO2 particles for characterization employing high-resolution transmission electron microscopy (HR-TEM) and powder X-ray diffraction (PXRD). All samples considered in this study meet agreeable TiO2 % (m/m) levels as specified by all health regulatory bodies. Both forms of TiO2: anatase and rutile, were found to be present. Most samples contained nano-TiO2 in the particle size range of 16.23 nm to 51.47 nm that could lead to detrimental effects. The fact that the anatase form, known for its photocatalytic activity, was present, is a cause for concern.

Prediction of sediment transport capacity based on slope gradients and flow discharge

Sediment transport capacity (Tc) is an essential parameter in the establishment of the slope soil erosion model. Slope type is an important crucial factor affecting sediment transport capacity of overland flow, and vegetation can effectively inhibit soil loss. Two new formulae of sediment transport capacity (Tc) are proposed of brown soil slope and vegetation slope in this study and evaluate the influence of slope gradient (S) and flow discharge (Q) on sediment transport capacity of different slope types. Laboratory experiments conducted using four flow discharges (0.35, 0.45, 0.55, and 0.65 L s-1), four slope gradients (3, 6, 9, and 12°), and two kinds of underlying surface (Brown soil slope, Vegetation slope). The soil particle size range is 0.05–0.5mm. The vegetation stems were 2mm in diameter and randomly arranged. The results show that the sediment transport capacity was positively correlated with the flow discharge and slope gradient. The vegetation slope’s average sediment transport capacity is 11.80% higher than the brown soil slope that same discharge and slope gradient conditions. The sensitivity of sediment transport capacity to flow discharge on brown soil slope is higher than that of slope gradient. The sensitivity of sediment transport capacity of vegetation slope to slope gradient is more heightened than flow discharge. The sediment transport capacity was well predicted by discharge and slope gradient on brown soil slope (R2 = 0.982) and vegetation slope (R2 = 0.993). This method is helpful to promote the study of the sediment transport process on overland flow.

Revisiting the Gage–Bidwell Law of Dilution in Relation to the Effectiveness of Swimming Pool Filtration and the Risk to Swimming Pool Users from Cryptosporidium

The transfer of water from a swimming pool to the treatment location is key in determining the effectiveness of water treatment by filtration in removing turbidity and managing the risk from particulate material, including microbial pathogens, such as Cryptosporidium spp. A key recommendation for pool operators when dealing with an accidental faecal release (the likely main source of high Cryptosporidium oocyst concentrations in pools) is that the pool water should be filtered for at least six turnover cycles prior to use. This paper briefly outlines the theoretical basis of what has become known as the Gage–Bidwell Law of Dilution, which provides a basis for this recommendation, and extends the idea to account for the impact of filter efficiency. The Gage–Bidwell Law reveals that for each pool turnover 63% of the water resident in the pool at the start of the turnover period will have been recirculated. Building on this, we demonstrate that both filter efficiency and water-turnover time are important in determining filtration effectiveness and can be combined through a single parameter we term ‘particle-turnover’. We consider the implications of the Gage–Bidwell Law (as referred to in the original 1926 paper) for the dynamics of the ‘dirt’ content of pool water, whether in terms of a specific particle size range (e.g., Cryptosporidium oocysts) or turbidity.