Concentration Of Small Particles Research Articles

Consolidated sediment resuspension in model vegetated canopies

Aquatic plants, turbulence and sediment fluxes interact with each other in a complex, non-linear fashion. While most studies have considered turbulence as being generated primarily by mean flow, it can, however, also be generated by the action of the wind or by the night cooling convection at the surface of the water column. Here, we study turbulent interaction with vegetation and the effects it has on sediment suspension, in the absence of mean flow. In a water tank containing a base layer of sediment, turbulence was generated by oscillating a grid with the main objective being to determine the differences in sediment resuspension in sediment beds over a wide range of consolidation times (1 h–3 days), for a set of model canopies with different structural characteristics: density and flexibility, and for three types of sediment beds. The greater the consolidation time was, the lower the sediment resuspension. For bed consolidation times below 6 h, the concentration of resuspended sediment was approximately constant and had no dependence on turbulence intensity. However, for higher bed consolidation times, between 6 and 3 days, the resuspension of the sediment beds increased with turbulence intensity (defined in terms of turbulent kinetic energy; TKE hereafter). The TKE within the sparse flexible canopies was higher than that in the sparse rigid canopies, while within the dense flexible canopies it was below that of the rigid canopies. Therefore, the sediment resuspension in the sparse flexible canopies was greater than that of the sparse rigid canopies. In contrast, the sediment resuspension in the dense flexible canopies was lower than that of the dense rigid canopies. Using different sediment types, the results of the study indicate that sediments with greater concentrations of small particles (muddy beds) have higher concentrations of resuspended sediment than sediment beds that are composed of larger particle sizes (sandy beds).

MENOPAUSAL STAGE INFLUENCES LIPOPROTEIN SUBCLASS PROFILE IN HABITUALLY ACTIVE WOMEN

Menopause is associated with increased cardiovascular disease risk, in part due to worsening cholesterol profile with advancing menopausal stage. The effect of menopausal stage on lipoprotein cholesterol, lipoprotein particle size and number in active midlife women has not been evaluated.PURPOSETo evaluate differences in lipoprotein subclass concentrations between highly‐fit, habitually active women at distinct menopausal stages.METHODSWomen (40–65 yr) were healthy habitually active highly‐fit pre‐, peri‐, and postmenopausal women (PRE, n = 10, VO2peak = 47.0 ± 2.4 ml/kg/min, PERI, n = 12, VO2peak = 49.1 ± 2.4 ml/kg/min, and POST, n = 13, VO2peak = 43.8 ± 1.8 ml/kg/min). Menopausal stage was defined using the STRAW+10 criteria. Particle subclass concentrations and mean particle sizes (were measured using nuclear magnetic resonance spectroscopy (LabCorp). Calculated lipids (total triglyceride, total VLDL and chylomicron triglyceride, and total HDL cholesterol) were also analyzed. Blood samples for lipoprotein particle analysis were collected during days 1–6 of the menstrual cycle for PRE. ANOVAs with Holm‐Sidak post hoc testing were used to determine differences between groups for each lipid outcome. Nonparametric tests were employed if assumptions were not met. Data are presented as mean ± SEM.RESULTSThere was a significant effect of menopause stage on total HDL cholesterol (p = 0.010) with greater HDL cholesterol in POST (88.5 ± 2.2 mg/dl) vs. PRE (72.2 ± 5.7 mg/dl, p = 0.032) and total HDL particle concentration (p = 0.010) with significantly greater total HDL particle concentration in POST (40.2 ± 1.1 μmol/L) compared with PRE (34.9 ± 1.5 μmol/L, p = 0.023) and POST compared with PERI (PERI, 35.5 ± 1.3 μmol/L, p = 0.033). There was a trend for an effect of menopausal status on large HDL particle concentration (p = 0.072) with progressively greater large HDL particle concentration with each advancing stage (PRE 12.1 ± 1.1 μmol/L, PERI, 14.0 ± 1.2 μmol/L, POST, 15.5 ± 0.6 μmol/L). There was no significant effect of menopausal stage on medium or small HDL particle concentration or HDL size (all p>0.05). There was an effect of menopausal stage on large LDL particle concentration (p = 0.039) with greater concentration of large LDL particles in PRE (479 ± 52.6 nmol/L) vs. POST (663 ± 47.5 nmol/L, p = 0.034) but no effect of menopausal stage on small LDL, IDL, or total LDL particle concentration, or LDL size (all p>0.05). There was no effect of menopausal status on any VLDL & chylomicron particle concentration or VLDL size (all p>0.05).CONCLUSIONThese data indicate that in healthy, highly fit women, advancing menopausal stage does not have a negative effect on many lipoprotein particle concentrations. Habitual physical activity may eliminate or potentially reverse some of the negative consequences of menopause on lipids.Support or Funding InformationFunding Sources: American College of Sports Medicine Foundation Doctoral Student Research Grant (Serviente), National Institute on Aging Grant T32‐AG049676 (Pennsylvania State University), University of Massachusetts Amherst Provost's Undergraduate Research Fellowship (Chalvin).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Validation of Nanoparticle Tracking Analysis in Characterizing Extracellular Vesicle Isolated from Polydisperse Biological Samples

Nanoparticle tracking analysis (NTA) has become a desired method of characterizing extracellular vesicles (EVs) in recent years. The NTA method is distinguished from other EV detection techniques by its ability to simultaneously analyze size and concentration measures in polydisperse EV samples. However, a recent study (Tian et al., 2016) suggested using a single parametric setting for sizing and counting of polydisperse particles in a broad size range is challenging. The OBJECTIVE of this study is to evaluate the accuracy of the NTA when analyzing polydisperse, biological EV samples isolated at different centrifugation speeds.METHODSHuman venous blood samples were collected in a 3.2% buffered sodium citrate‐containing tube. Plasma fraction was separated within 2 hours by a double centrifugation (2,500 g for 15 min each) and stored at −80 °C freezer until analyzed. Microvesicles were isolated from the plasma sample with an ultracentrifugation method using differing speeds (12,000 g, 16,000 g, 20,000 g, and 32,000 g) at 4 °C. Exosomes were isolated by double centrifugation (120,000 g for 70 min each) at 4°C from conditioned media from C2C12 myotubes. Samples of known size microsphere beads with 200, 500, and 800 nm diameters were evaluated in either monodisperse or polydisperse samples for comparison. The NanoSight NS300 was used to measure size distribution and concentration of the particles per manufacturer's procedures. All samples were analyzed using identical camera settings and detection parameters.RESULTSThe mean particle size was ranged from 140 nm to 222 nm across the EV samples from human blood. The mean particle size for exosomes from C2C12 cultured media was 204.0 ± 9.1 nm. There was no correlation of mean particle size with centrifugation speed. In all samples, higher concentrations of small particles (< 300 nm) and lower concentrations of larger particles (> 300 nm) were observed. In analyses of sized microsphere samples, monodisperse samples of 200 nm beads accurately measured expected size distribution with a high repeatability. Increases in concentrations by factors of 2 and 4 resulted in accurately measured increases for the 200 nm beads. In contrast, monodisperse samples of 500 and 800 nm beads measured lower concentrations when increased by the same factors. Results for polydisperse samples of 200, 500, and 800 nm beads, with equal concentration ratios (1:1:1) showed lower concentrations for 500 and 800 nm beads, compared to 200 nm (7.29×107, 3.78×107, vs, 10.3×107, respectively).CONCLUSIONRegardless of the actual composition of EV subpopulation, NTA measures an average particle size of ~200 nm in polydisperse samples. Analysis of synthetic size beads revealed that this may be because, at least in part, the NTA method underestimates the concentration for larger particles with a size greater than 200 nm. Our results suggest that caution should be used when analyzing polydisperse samples (i.e. serum/plasma) using a nanoparticle tracking method.Support or Funding InformationSupported by NIH Grant R01NS102157This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Small HDL, diabetes, and proinflammatory effects in macrophages

Atherosclerosis, an inflammatory disease of the arterial wall, is the commonest cause of cardiovascular disease (CVD) events. Elevated levels of high‐density lipoprotein (HDL) cholesterol are generally believed to protect against CVD and to reduce inflammatory activation of macrophages, a key cell type in lesions of atherosclerosis. However, HDL can also exert proinflammatory effects in macrophages by inducing cholesterol depletion. Because small HDL (7–8.5 nm diameter) is most effective in removing cholesterol from cells by the ABCA1 pathway, we hypothesized that small HDL is the most proinflammatory HDL population. Small‐, medium‐ and large HDL populations were isolated from a human apolipoprotein A‐I transgenic LDL receptor‐deficient mouse model (APOA1Tg;Ldlr−/−). Depletion of cholesterol by HDL increased the ability of toll‐like receptor (TLR) ligands to induce proinflammatory mediators in macrophages. This effect was prevented by cholesterol loading of the macrophages. Small HDL had a significantly stronger effect on Tnfa (3‐fold over LPS alone) and Il1b (2.5‐fold over LPS alone) gene expression than medium or large HDL particles. Inhibition or deletion of the sheddase ADAM17 in macrophages prevented the proinflammatory effects of HDL. Patients with type 1 diabetes mellitus (T1DM) exhibit an increased risk of CVD despite having normal or high HDL‐cholesterol. To investigate the effect of diabetes on HDL subpopulations, we crossed a virally‐induced mouse model of T1DM (Ldlr−/−;GpTg) with the human APOA1Tg;Ldlr−/− mouse. The mice (APOA1Tg;Ldlr−/−;GpTg, n=8–10) were injected with a liver‐specific adeno‐associated virus driving expression of human cholesteryl ester transfer protein (hCETP) to mimic human physiology. Diabetic mice had an increased HDL particle concentration (~2‐fold) associated with a significant increase in serum HDL cholesterol efflux capacity through both ABCA1 and ABCG1, compared with non‐diabetic mice. The largest increase was in the small HDL particle concentration (15 μM vs 6 μM in non‐diabetic mice). Moreover, resident peritoneal macrophages from diabetic mice exhibited increased cytokine gene expression, as compared with non‐diabetic littermates. Our findings demonstrate that higher levels of small HDL, as observed in a mouse model of diabetes, can exacerbate inflammatory activation in non‐lipid loaded macrophages in an ADAM17‐dependent manner. We have found similar changes in HDL concentration and function in humans with T1DM, suggesting that our mouse model might provide novel insights into CVD risk in T1DM patients.Support or Funding Informationfunded in part by the National Institutes of Health, grants DP3DK108209, P01HL092969, P30 DK017047, and P01HL128203This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Crystallization processes in a nonvibrating magnetic granular system with short range repulsive interaction

Applying an unsteady magnetic field to a 2D nonvibrating magnetic granular system induces a random motion in the steel beads with characteristics analogous to that of molecules in a fluid. We investigate the structural characteristics of the solid-like structures generated by different quenching conditions. The applied field is generated by the superposition of a constant field and a collinear sinusoidal field. The system reaches a quasi steady state in which the effective temperature is proportional to the amplitude of the applied field. By reducing the effective temperature at different rates, different cooling rates are produced. A slight inclination of the surface allows us to investigate the effects of small particle concentration gradients. The formation of a wide and rich variety of condensed solid structures, from gel-like and glass-like structures up to crystalline structures, is observed and depends on the cooling rate. We focus our attention on the crystallization process and found this process to be a collective phenomenon. We discuss our results in terms of the measured time evolution of the mean squared displacement, the effective diffusion coefficient, and the radial distribution function.

Optimization of the catalytic performance of Pd/Fe3O4 nanoparticles prepared via microwave-assisted synthesis for pharmaceutical and catalysis applications

Microwave assisted synthesis technique was used to prepare palladium supported on iron oxide nanoparticles. The advantage of using microwave irradiation as a synthetic tool is due to its unique features as a one step, simple, versatile, and rapid process. The reactants are added simply at room temperature without using high-temperature injection. Hydrazine hydrate was added by the following ratios (0.1, 0.2, 0.3, 0.4, 0.6, 0.8, 1, 1.6, and 3) ml to the different prepared samples at room temperature in order to investigate its effect on the catalytic performance of the prepared catalysts. The prepared catalyst could be used as an ideal candidate not only for Pharmaceutical industry through cross-coupling reactions but also for low temperature oxidation catalysis of carbon monoxide and pharmaceutical applications as well. The experimental results showed that Pd/Fe3O4 catalyst has a remarkable catalytic activity for carbon monoxide oxidation catalysis due to the strong interaction between palladium and iron oxide nanoparticles. This may be due to the small particle size (7-14 nm) and concentration ratio of the Pd nanoparticles dispersed on the surface of magnetite (Fe3O4). Those nanoparticles were characterized by various spectroscopic techniques including; X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Vibrating Sample Magnetometer (VSM) and transmission electron microscopy (TEM).

Interpretation of particle number size distributions measured across an urban area during the FASTER campaign

Abstract. Particle number size distributions have been measured simultaneously by scanning mobility particle sizers (SMPSs) at five sites in central London for a 1 month campaign in January–February 2017. These measurements were accompanied by condensation particle counters (CPCs) to measure total particle number count at four of the sites and Aethalometers measuring black carbon (BC) at five sites. The spatial distribution and inter-relationships of the particle size distribution and SMPS total number counts with CPC total number counts and black carbon measurements have been analysed in detail as well as variations in the size distributions. One site (Marylebone Road) was in a street canyon with heavy traffic, one site (Westminster University) was on a rooftop adjacent to the Marylebone Road sampler, and a further sampler was located at Regent's University within a major park to the north of Marylebone Road. A fourth sampler was located nearby at 160 m above ground level on the BT tower and a fifth sampler was located 4 km to the west of the main sampling region at North Kensington. Consistent with earlier studies it was found that the mode in the size distribution had shifted to smaller sizes at the Regent's University (park) site, the mean particle shrinkage rate being 0.04 nm s−1 with slightly lower values at low wind speeds and some larger values at higher wind speeds. There was evidence of complete evaporation of the semi-volatile nucleation mode under certain conditions at the elevated BT Tower site. While the SMPS total count and black carbon showed typical traffic-dominated diurnal profiles, the CPC count data typically peaked during night-time as did CPC∕SMPS and CPC∕BC ratios. This is thought to be due to the presence of high concentrations of small particles (2.5–15 nm diameter) probably arising from condensational growth from traffic emissions during the cooler night-time conditions. Such behaviour was most marked at the Regent's University and Westminster University sites and less so at Marylebone Road, while at the elevated BT Tower site the ratio of particle number (CPC) to black carbon peaked during the morning rush hour and not at night-time, unlike the other sites. An elevation in nucleation mode particles associated with winds from the west and WSW sector was concluded to result from emissions from London Heathrow Airport, despite a distance of 22 km from the central London sites.

Specific heat measurements of CNT nanofluids

There have been numerous research studies regarding nanofluid for last two decades. The major topic was mostly focused on the thermal conductivity increase with small particle concentration. However, a conclusion regarding thermal conductivity increase and heat transfer mechanism was not achieved yet due to large discrepancies among the experimental results. In parallel with the thermal conductivity, the specific heat is a crucial thermal property in the application of the nanofluid but wide research has not been conducted. In this study, the specific heat of carbon nanotube (CNT) nanofluids were experimentally measured and the experimental results were compared with possible models to explain the results. The CNT nanofluids were produced with DI water and ethylene glycol (EG) as base fluids. Since CNTs are not mixed with DI water, gum Arabic was used as a surfactant. On the other hand, CNTs were mixed with EG without any surfactant. The specific heat was measured with Calvet calorimeter. Temperature and heat flow sensors of Calvet calorimeter were calibrated with reference materials. The experiment method was validated by comparing the base fluids with reference values showing very good agreement. The measured specific heat of CNT nanofluids decreased with particle concentration due to the lower specific heat of CNT than that of base fluids. It is found that the thermal equilibrium model of nanofluid specific heat successfully predicts the experimental results. This result can be very useful in generating desired working fluids in the diverse thermal systems because the control of the specific heat of nanofluid can be achieved.

Relationships Between Aerosol Particles and Airborne Bacteria and their Dependence on Environmental Factors in a Dairy Calf House

Abstract. The quality of indoor air dramatically affects the health of animals and humans. An investigation was conducted into the relationships among the total number of aerosol particles and different types of airborne bacteria and their dependence on indoor and outdoor environmental factors, including air temperature and relative humidity (RH), in the indoor air of a dairy calf house in Tochigi, Japan, during the summer season. The concentrations of aerosol particles, the concentrations of airborne total aerobic bacteria (, , and spp.) in the indoor air, and the indoor and outdoor temperature and RH were evaluated from 14 weekly measurements. The mean concentration of small aerosol particles (0.3 to 2.0 µm) was higher than the mean concentration of large aerosol particles (2.0 to 10.0 µm) in the summer season. The mean concentration of airborne total aerobic bacteria was higher than the concentrations of airborne , , and spp. Airborne and were positively correlated with the number of 2.0 to 10.0 µm aerosol particles, i.e., high concentrations of 2.0 to 10.0 µm particles were correlated with high concentrations of airborne and . Airborne total aerobic bacteria did not correlate with the number of aerosol particles of any size, but spp. was negatively correlated with the number of 1.0 to 2.0 µm aerosol particles, i.e., high concentrations of 1.0 to 2.0 µm particles were correlated with low concentrations of airborne spp. The indoor temperature and indoor and outdoor RH did not correlate with any airborne bacteria. The outdoor temperature was negatively correlated with spp., i.e., high outdoor temperature was correlated with a low concentration of spp. in the indoor air of the dairy calf house. Both indoor and outdoor temperatures were positively correlated with the number of 0.5 to 5.0 µm aerosol particles, and indoor RH was negatively correlated with the number of 5.0 to 10.0 µm aerosol particles. These findings will be important for elucidating the role of aerosol particles in the transmission of airborne bacteria and ultimately for the mitigation of aerosol particles and airborne bacteria in dairy houses. HighlightsThe number of fine aerosol particles increased with increasing temperatures.Environmental factors had a less critical effect on airborne bacteria than aerosol particles.Airborne E. coli strongly positively correlated with 5.0 to 10.0 µm aerosol particles.Airborne Salmonella spp. negatively correlated with 1.0 to 2.0 µm aerosol particles.Relative humidity did not affect any airborne bacteria. Keywords: Aerosol particle number, Airborne bacteria, Dairy calf, Indoor air, Relationship, Summer season.

Exercise is Associated With Increased Small HDL Particle Concentration and Decreased Vascular Stiffness in Rheumatoid Arthritis.

Patients with rheumatoid arthritis (RA) have increased cardiovascular (CV) risk. In the general population, exercise improves several CV risk factors. In a cross-sectional study, we examined the hypothesis that more exercise is associated with protective traditional and non-traditional CV risk factor profile in patients with RA. Patient-reported exercise outside of daily activities was quantified by time and metabolic equivalents per week (METmin/week) and CV risk factors including blood pressure, standard lipid profiles, lipoprotein particle concentrations (NMR spectroscopy), and vascular indices were measured in 165 patients with RA. The relationship between exercise and CV risk factors was assessed according to whether patients exercised or not, and after adjustment for age, race and sex. Over half (54%) of RA patients did not exercise. Among those who did exercise, median value for exercise duration was 113 min/week [IQR: 60, 210], and exercise metabolic equivalent expenditure was 484 METmin/week [IQR: 258, 990]. Disease activity (measured by DAS28 score), C-reactive protein, waist-hip ratio, and prevalence of hypertension were lower in patients who exercised compared to those who did not (all p-values < 0.05) but standard lipid profile and body mass index were not significantly different. Patients who exercised had significantly higher concentrations of HDL particles (p = 0.004) and lower vascular stiffness as measured by pulse wave velocity (p = 0.005). More self-reported exercise in patients with RA was associated with a protective CV risk factor profile including lower waist-hip ratio, higher HDL particle concentration, lower vascular stiffness, and a lower prevalence of hypertension.

Lipoprotein Particle Profiles, Standard Lipids, and Peripheral Artery Disease Incidence

Despite strong and consistent prospective associations of elevated low-density lipoprotein (LDL) cholesterol concentration with incident coronary and cerebrovascular disease, data for incident peripheral artery disease (PAD) are less robust. Atherogenic dyslipidemia characterized by increased small LDL particle (LDL-P) concentration, rather than total LDL cholesterol content, along with elevated triglyceride-rich lipoproteins and low high-density lipoprotein (HDL) cholesterol (HDL-C), may be the primary lipid driver of PAD risk. The study population was a prospective cohort study of 27 888 women ≥45 years old free of cardiovascular disease at baseline and followed for a median of 15.1 years. We tested whether standard lipid concentrations, as well as nuclear magnetic resonance spectroscopy-derived lipoprotein measures, were associated with incident symptomatic PAD (n=110) defined as claudication and/or revascularization. In age-adjusted analyses, while LDL cholesterol was not associated with incident PAD, we found significant associations for increased total and small LDL-P concentrations, triglycerides, and concentrations of very LDL (VLDL) particle (VLDL-P) subclasses, increased total cholesterol (TC):HDL-C, low HDL-C, and low HDL particle (HDL-P) concentration (all P for extreme tertile comparisons <0.05). Findings persisted in multivariable-adjusted models comparing extreme tertiles for elevated total LDL-P (adjusted hazard ratio [HRadj] 2.03; 95% CI, 1.14-3.59), small LDL-P (HRadj 2.17; 95% CI, 1.10-4.27), very large VLDL-P (HRadj 1.68; 95% CI, 1.06-2.66), medium VLDL-P (HRadj 1.98; 95% CI, 1.15-3.41), and TC:HDL-C (HRadj, 3.11; 95% CI, 1.67-5.81). HDL was inversely associated with risk; HRadj for extreme tertiles of HDL-C and HDL-P concentration were 0.30 ( P trend < 0.0001) and 0.29 ( P trend < 0.0001), respectively. These components of atherogenic dyslipidemia, including small LDL-P, medium and very large VLDL-P, TC:HDL-C, HDL-C, and HDL-P, were more strongly associated with incident PAD than incident coronary and cerebrovascular disease. Finally, the addition of LDL-P and HDL-P concentration to TC:HDL-C measures identified women at heightened PAD risk. In this prospective study, nuclear magnetic resonance-derived measures of LDL-P, but not LDL cholesterol, were associated with incident PAD. Other features of atherogenic dyslipidemia, including elevations in TC:HDL-C, elevations in triglyceride-rich lipoproteins, and low standard and nuclear magnetic resonance-derived measures of HDL, were significant risk determinants. These data help clarify prior inconsistencies and may elucidate a unique lipoprotein signature for PAD compared to coronary and cerebrovascular disease. URL: https://www.clinicaltrials.gov/ . Unique Identifier: NCT00000479.

Impact of indoor-outdoor temperature differences on dispersion of gaseous pollutant and particles in idealized street canyons with and without viaduct settings

Computational fluid dynamics simulations were performed to investigate flow and pollutant dispersion in a 2D street canyon of aspect ratio H/W = 1. Different from other works, the combination of the presence of viaduct and indoor-outdoor temperature differences ΔT is investigated for different approaching wind velocities. For larger wind velocity (2 m/s, Froude number Fr~3.06–12.24) the typical clockwise vortex leads to higher concentrations of both gas and small particles at the leeward side of the street and in the leeward-side rooms; the vortex is enhanced under large ΔT (20 K) improving the dispersion of pollutants. For smaller velocity (0.5 m/s, Fr~0.19–0.77) the appearance of an anti-clockwise vortex leads to a strong accumulation of gas and particles at the windward side and in the windward-side rooms under low ΔT (5 K); increasing the ΔT raises the dispersion of pollutants with consequent lower concentrations in the rooms (up to an average of 67% with respect to the isothermal case for gaseous pollutants), but accumulation close to the ground level at both windward-side and leeward-side rooms. In the presence of viaduct, together with the main vortex above the viaduct which causes concentrations increasing from low-level to high-level leeward-side rooms, two vortices are generated below it. Still ΔT = 20 K improves the dispersion of pollutants, leading up to a maximum of about 30% lower gaseous concentrations in the rooms. In general, lower concentrations of gas and particles are found for larger velocity, indicating that the mechanical turbulence dominates over the buoyancy effects, which become crucial for smaller velocity. This study confirms previous findings that viaducts may improve pollutant dispersion under large velocity if only one viaduct-level pollutant source exists and indoor-outdoor ΔT conditions can mitigate street air pollution.

Asymmetric concentration dependence of segregation fluxes in granular flows

We characterize the local concentration dependence of segregation velocity and segregation flux in both size and density bidisperse gravity-driven free-surface granular flows as a function of the particle size ratio and density ratio, respectively, using discrete element method (DEM) simulations. For a range of particle size ratios and inlet volume flow rates in size-bidisperse flows, the maximum segregation flux occurs at a small particle concentration less than 0.5, which decreases with increasing particle size ratio. The segregation flux increases up to a size ratio of 2.4 but plateaus from there to a size ratio of 3. In density bidisperse flows, the segregation flux is greatest at a heavy particle concentration less than 0.5 which decreases with increasing particle density ratio. The segregation flux increases with increasing density ratio for the extent of density ratios studied, up to 10. We further demonstrate that the simulation results for size driven segregation are in accord with the predictions of the kinetic sieving segregation model of Savage and Lun.

Mineralogy and facies variations of Devonian and Carboniferous shales in the Ukrainian Dniepr-Donets Basin

Abstract The mineralogy of Devonian to Carboniferous shales from the Ukrainian Dniepr-Donets Basin (DDB) was investigated during this study. These shales show a high compositional variability in vertical and lateral directions. Furthermore, stratigraphic trends were found to be controlled both by climatic factors as well as by changing detrital input from the hinterland. High kaolinite contents and predominance of kaolinite over illite in the Tournaisian and partly in the lower Visean units are likely a result of intense chemical weathering related to the Hangenberg climatic event at the Devonian/ Tournaisian boundary. In contrast, abnormally high kaolinite contents in upper Visean and Serpukhovian samples at the basin center might be caused by different transport properties of kaolinite and illite, leading to selective concentration of small detrital kaolinite particles, which are often in the sub-micrometer range according to scanning electron microscopy observations. K/Al elemental ratios correlate well with illite/kaolinite ratios for samples in which significant amounts of both clay minerals are present, which enables a pre-evaluation of the relative kaolinite content based on bulk geochemical data. As kaolinite is suggested to decrease the fraccability of shales and to have a great influence on their wetting behaviour, this is useful information for explorational purposes. Higher feldspar contents in Devonian and Tournaisian samples, especially along the NE basin margin and in the shallow NW part of the DDB, are likely related to increased detrital input from magmatic precursors (e.g. in the Voronezh Massif ) during (and shortly after) the active rift stage of the DDB. In general, feldspar contents are higher in proximal positions compared to the basin center, which is likely a result of shorter transport distances of the comparably large feldspar grains. Finally, the presence of expandable clay minerals down to depths of 6 km and the fact that no thermal maturity trend is visible down to these depths, proves, that a low post-depositional heat flow was present in the DDB. This is in good agreement with vitrinite reflectance measurements and thermal modelling results from previous studies, which suggest a low Mesozoic heat flow.

A global scavenging and circulation ocean model of thorium-230 and protactinium-231 with improved particle dynamics (NEMO–ProThorP 0.1)

Abstract. In this paper we set forth a 3-D ocean model of the radioactive trace isotopes 230Th and 231Pa. The interest arises from the fact that these isotopes are extensively used for investigating particle transport in the ocean and reconstructing past ocean circulation. The tracers are reversibly scavenged by biogenic and lithogenic particles. Our simulations of 230Th and 231Pa are based on the NEMO–PISCES ocean biogeochemistry general circulation model, which includes biogenic particles, namely small and big particulate organic carbon, calcium carbonate and biogenic silica. Small and big lithogenic particles from dust deposition are included in our model as well. Their distributions generally compare well with the small and big lithogenic particle concentrations from recent observations from the GEOTRACES programme, except for boundary nepheloid layers for which, as of today, there are no non-trivial prognostic models available on a global scale. Our simulations reproduce 230Th and 231Pa dissolved concentrations: they compare well with recent GEOTRACES observations in many parts of the ocean. Particulate 230Th and 231Pa concentrations are significantly improved compared to previous studies, but they are still too low because of missing particles from nepheloid layers. Our simulation reproduces the main characteristics of the 231Pa∕230Th ratio observed in the sediments and supports a moderate affinity of 231Pa to biogenic silica as suggested by recent observations relative to 230Th. Future model development may further improve understanding, especially when this will include a more complete representation of all particles, including different size classes, manganese hydroxides and nepheloid layers. This can be done based on our model as its source code is readily available.

CONCENTRATION AND SIZE OF AIRBORNE PARTICLES IN MANUFACTURING ENVIRONMENTS

ABSTRACT In furniture factories, the cutting of medium density fiberboard (MDF) generates high concentrations of particulates suspended in the air, which, depending on their dimensions, can reach the sensitive areas of the respiratory tract of workers. The aim of this study was to test a method to measure particle sizes derived from the cutting of wood paneling. The experiment was conducted in two small furniture factories located in the municipality of Lavras, Minas Gerais state, Brazil. During the cutting of MDF, airborne particles were collected and measured by means of optical microscopy. The data obtained showed a critical condition in the work environments, with high concentrations of small particles (&lt;10 microns), which could be lodged in the workers’ lungs. The particle measuring process proved to be accurate and easy to perform. In addition, it is worth noting the importance of investment in personal protective equipment (PPE) such as hoods and/ or PFF2 dust masks for the protection of workers.

Two TAGSNPS in PCSK9 are associated with tg metabolism in patients with type 2 diabetes and metabolic syndrome

Aim: LDLc is normal in diabetic patients who conversely tend to have increased TG, low HDL and increased concentration of small LDL and HDL particles (atherogenic dyslipidemia (AD)). Paradoxically, although PCSK9 is among the strongest regulators of LDLc concentration we demonstrated that it promotes AD in diabetic patients. We have tested whether the relation between PCSK9 and AD is genetically driven.

The impact of ground-based glaciogenic seeding on a shallow stratiform cloud over the Sierra Madre in Wyoming: A multi-sensor study of the 3 March 2012 case

A case study is presented of the impact of ground-based glaciogenic seeding on a shallow, lightly precipitating orographic storm with abundant supercooled cloud droplets, but few ice particles. The storm was observed on 3 March 2012 as part of the AgI (silver iodide) Seeding Cloud Impact Investigating (ASCII) experiment in Wyoming. The cloud base temperature was about −9 °C, and cloud tops were at about −16 °C. The high concentration of small droplets and low ice particle concentration lead to natural snow growth, mainly by vapor diffusion. The question addressed here is whether the injection of ice nucleating particles (AgI) enhanced snow growth and snowfall. The treated (seeded) period is compared with the preceding untreated (noseeded) period, and natural trends (observed in an adjacent control region) are removed. The main target site, located on a mountain pass at an elevation above cloud base, was impacted by AgI seeding, according to a trace chemistry analysis of freshly fallen snow.Data from three radar systems were used: the Wyoming Cloud Radar, two Ka-band profiling Micro-Rain Radars, and a X-band scanning Doppler-on-Wheels (DOW) radar. Composite data from these radar systems and from gauges in the target area indicate an increase in low-level reflectivity and precipitation rate during seeding. This finding generally agrees with other published ASCII case studies. The increase in reflectivity during seeding in the target area appears to be due mainly to an increase in particle size (aggregation), not number concentration, as suggested by DOW differential reflectivity and by disdrometer and Cloud Particle Imager measurements on the ground.

Breaking size-segregation waves and mobility feedback in dense granular avalanches

Through experiments and discrete particle method (DPM) simulations we present evidence for the existence of a recirculating structure, that exists near the front of dense granular avalanches, and is known as a breaking size-segregation (BSS) wave. This is achieved through the study of three-dimensional bidisperse granular flows in a moving-bed channel. Particle-size segregation gives rise to the formation of a large-particle-rich front and a small-particle-rich tail with a BSS wave positioned between the tail and front. We experimentally resolve the structure of the BSS wave using refractive-index matched scanning and find that it is qualitatively similar to the structure observed in DPM simulations. Our analysis demonstrates a relation between the concentration of small particles in the flow and the amount of basal slip, in which the structure of the BSS wave plays a key role. This leads to a feedback between the mean bulk flow velocity and the process of particle-size segregation. Ultimately, these findings shed new light on the recirculation of large and small grains near avalanche fronts and the effects of this behaviour on the mobility of the bulk flow.

Pattern Formation in Binary Colloidal Assemblies: Hidden Symmetries in a Kaleidoscope of Structures

In this study, we present a detailed investigation of the morphology of binary colloidal structures formed by self-assembly at air/water interface of particles of two different sizes, with a size ratio such that the larger particles do not retain a hexagonal arrangement in the binary assembly. While the structure and symmetry of binary mixtures in which such hexagonal order is preserved has been thoroughly scrutinized, binary colloids in the regime of nonpreservation of the hexagonal order have not been examined with the same level of detail due also to the difficulty in finding analysis tools suitable to recognize hidden symmetries in seemingly amorphous and disordered arrangements. For this purpose, we resorted to a combination of different analysis tools based on computational geometry and computational topology to get a comprehensive picture of the morphology of the assemblies. By carrying out an extensive investigation of binary assemblies in this regime with variable concentration of smaller particles with respect to larger particles, we identify the main patterns that coexist in the apparently disordered assemblies and detect transitions in the symmetries upon increase in the number of small particles. As the concentration of small particles increases, large particle arrangements become more dilute and a transition from hexagonal to rhombic and square symmetries occurs, accompanied also by an increase in clusters of small particles; the relative weight of each specific symmetry can be controlled by varying the composition of the assemblies. The demonstration of the possibility to control the morphology of apparently disordered binary colloidal assemblies by varying experimental conditions and the definition of a route for the investigation of disordered assemblies are important for future studies of complex colloidal patterns to understand self-assembly mechanisms and to tailor the physical properties of colloidal assemblies.